Day #159 - Fever of Unknown Origin - The Return

Due to fun rounds time constraints -- will point you to my previous blogs on FUO -- here.

Day #153 - Pneumocystis (PCP) Redux

Today we heard a case of PCP pneumonia with a classic presentation. For those of you who will end up doing medical education -- you should start saving up cases during your residency that you can use as exemplars of diagnoses, management, or approaches -- especially if they have key teaching points or interesting imaging. This will also help you for when you are suddenly called upon to provide impromptu teaching.

I have previously blogged in detail about PCP here. This blog links to a number of other blogs and articles that are also useful.

Day# 146 - Two cases

We talked about a case of stroke in a young patient. An approach to stroke in a young patient is outlined briefly here.

The case turned out to be meningovascular syphilis.

Here is an interesting article on the history of syphilis and another which talks about whether or not Shakespeare himself was infected.

The second case was that of massive liver enzyme elevation with synthetic dysfunction. I have previously blogged about hepatitis here.

Day #145 - Pyogenic Liver Abscess

Today we heard about a great case of pyogenic liver abscess. I wanted to clarify a few points of discussion.

Pathogenesis (most common in blue):

• Ascention of pathogens up biliary tree
• Ascention of pathogens through portal circulation. Often in the context of an intraabdominal nidus of infection like diverticulitis. May be in context of septic portal thrombophlebitis
• Cyptogenic
• Direct innoculation from trauma or iatrogenic
• Hematogenous spread from systemic infection
• Direct spread from gallbladder infection

Pathogens

• Gpc - strep milleri and other alpha haemolytic strep.
• Gnr - ecoli and klebsiella. Anaerobes (which often won't grow in culture)
  

• Amoebic liver abscess
• Hydadid cyst disease (echinococcus)

Treatment:

Pyogenic - use emperic coverage that will cover most pathogens above - I.e. Pip/tazo or ceftriaxone/metronidazole. Narrow spectrum to culture results not forgetting anaerobes

Drainage - either IR or surgical -- "Never let the sun set on undrained pus"

Amoebic - metronidazole 750po TID x 10 days followed by luminocidal agent

Hydadid - Specialized surgical care.

Day #126 - Hepatitis B

Today we discussed a patient with acute hepatitis on the backgroud of hepatitis B chronic infection. I have previously discussed acute hepatitis, cirrhosis and complications thereof.

I wanted to talk about hepatitis B -- Firstly, this is a great review article and so is this.

Secondly - Serologies:

• Early in infection you have the production of Hepatitis B Surface Antigen and Hepatitis B Envelope Antigen which represents active infection
• The you develop hepatitis B core IgM then core IgG. These antibodies are not protective
• If you are going to clear your infection you will next develop anti-hepatitis B-EAg antibodies, clear your E antigen and then start to clear your S-Antigen
• You then make hepatitis B surface antibodies
• There can be a window period in between clearing the S-Ag and developing the anti-HepB surface antibody where the only way you will know if they are infected is by the core antibody.

An immunized person will only have hepatitis B surface antibody

A natural, but cleared infection will have positive HepB surface antibody and core antibody and no surface antigen

A patient with chronic active hepatitis will have core antibody and in most cases hepatitis B surface antigen. They may also have E antigen (or E antibody). They will not have surface antibody.

For chronic carriers treatment depends on a number of factors -- this table provides an excellent summary:

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Note that I link to a lot of NEJM articles. This is my preferred journal. Those of you with a U of T library account have NEJM access via e-journal search in the gerstein library website. We pay for an institutional license @ U of T which you can access at home and there is a licence here at the hospital.

Those of you who would like their own subscription (b/c above don't work) can obtain one here ($~60/year for electronic only ~ $150 for print copy too)

Day #124 - Pretibial Septic Bursitis

Today's case was of a painter, who did a lot of work on his hands and knees, presenting with acute onset knee pain. We discussed the differential diagnosis in detail and then focused on septic arthritis. I have previously blogged about this here and had linked to an excellent article that I recommend you reading.

In this case, the diagnosis was pretibial septic bursitis, which can mimic septic arthritis and is commonly seen in people who do labor on their hands and knees and is associated with minor traumas. The most common infectious aetiology is stapylococcus aureus.

Day #119 - Adult Onset Still's Disease

This was a great case which the discussant enjoyed taking us through. I have previously blogged about fever of unknown origin here, here and here.

There was a previous special guest blog about FUO here.

Here are articles suggested by the discussant on rheumatologic causes of FUO, Adult Onset Still's Disease, and the use of IL-1 antagonists in the treatment of Still's.

Here is another review on Stills.

Day #118 - Probable Leptospirosis

Today we heard a case of a returning traveller who suffered complete cardiorespiratory collapse as part of a sepsis syndrome. In this syndrome the patient was hypotensive requiring inopressors, hypoxemic/hypercapnic requiring ventillation, coagulopathic with a microangiopathic hemolytic anemia (see TTP blog and previous anemia/thrombocytopenia blogs) from DIC, and in acute renal failure. In the context of this illness he suffered either myocarditis or a myocardial infarction related to hypoperfusion.

This was as sick as anyone can be and survive and it is a testiment to our critical care system that he did indeed survive.

We spent time discussing the approach to diarrhea, which was his initial presenting symptom.

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We then defined sepsis

SIRS Criteria:

• Fever or hypothermia
  
• WBC >12,000 or less than 4,000
• HR >90
• RR >20

Sepsis = 2 or more SIRS criteria of presumed infective etiology
Severe sepsis includes sepsis with end organ dysfunction or lactate >4
Septic shock includes severe sepsis with refractory hypotension requiring inopressors

We then talked about the approach to early goal directed therapy in sepsis.

In this case, I believe early appropriate antibiotic therapy would include:

• Vancomycin (in case of community associated MRSA in a young man)
• Meropenem (to cover streptococcus, gram negatives including ESBL/drug resistant)
• Doxycycline to cover leptospirosis

In general, in a critically ill patient like this, I will draw cultures and then use very broad spectrum coverage empirically with a plan to de-escallate when culture results are available

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The etiology in this case is unclear but I wonder about leptospirosis. I didn't really want to talk about leptospirosis in detail during the case presentation.... This is the case of leptospirosis in NEJM that I elluded to.

I have provided you with a copy of a talk I once gave on leptospirosis here.

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Free tidbits:

Here is an article on fever in the returning traveller
A good review of typhoid fever is here.

Day #113 - Fever of Unknown Origin (FUO)

Today we talked about a case of true FUO. The discussant is published on the issue and I have linked to that article in previous blogs.

FUO blog #1
FUO blog #2

Day #111 - TB Pleuritis

Today we talked about a great case.

There is a *great* free resource called the Canadian Tuberculosis Standards available here.

First we talked about the diagnosis and treatment of latent tuberculosis infection.

Diagnosis:

• Positive mantoux test
  
  • Interpret in context of patient's history
    
    • less than 5mm - negative (or false negative in immunosuppressed or very ill patient)
    • 5mm-10mm - HIV, close contact with known case, chest xray evidence of old TB as fibronodular disease, children, immunosuppression (chemo, TNF alpha, high dose steroids)
    • Greater than 10 - positive for all others
    • Increase in 6 from previous known positive.
      
  • BCG -- only consider BCG as the cause of a TST if it was given after 12 months of age to a patient from a low risk country and does not have radiographic evidence of old TB
• Can consider inferferon based assay, though this is not the standard
  
• Evidence of prior tuberculosis on imaging
• No evidence of active disease

Treatment:

• Tend to treat people who are at the highest risk of re-activating or those with the lowest risk of drug side-effects
  
  • High risk includes: HIV, organ transplant, TNF alpha inhibitors and other immunosuppression
  • Risk in health normal person is ~ 5% in first 2 years and 10% over the lifetime
  • Immigration and reactivation risk
    
• INH 300mg PO OD x 9 months with Vitamin B6 25mg po OD
• Alternative (not as good): RIFAMPIN 600mg po OD x 4 months

We then talked about diagnosis and treatment of TB pleuritis

Diagnosis:

Acute to subacute illness (2/3 present less than 1 month) with fever, pleuritic chest pain, minimally productive cough. Unilateral effusion.

• Exudative effusion
• pH usually ~ 7.4
• Glucose usually normal
  
• Lymphocytic pleocytosis (though can be neutrophils early)
  
• Usually less than 5% mesothelial cells
• AFB stain less than 10%
• Culture ~ 30% (yield may improve by inoculating into special culture media)
  
• PCR positive in 90-100% of culture positive but only 30-60% of culture negative
• Sputum positive in ~ 50%
• Pleural biopsy shows either granulomas or AFB or is culture positive in up to 95%
  

• Measurement of Adenosine Deaminase
• The future: Other novel tests

Treatment:

• INH, RIF, ETH (add PZA if sputum positive, sick, bilateral effusions, other extrapulmonary disease) x 2 months then if INF/RIF sensitive INF/RIF to complete 6 months
• Adjuvant steroids are not clearly indicated
  
• Effusion may take up to 6 months post treatment to resolve.
  

Day #101 - Eosinophilia

Today we discussed a case of hypereosinophilia.

We discussed the differential diagnosis of eosinophilia including:

• Idiopathic Hypereosinophilic Syndrome (HES)
  
• Eosinophilic malignancies
• Systemic mastocytosis
  
• Associated with lymphoma (IL5 production)
  
• Infections
  
  • Parasitic (during tissue invasion): strongyloidiasis, ascariasis, hook worm, angiostronyliasis, liver flukes (fasciolysis, chlonorcis), trichenosis, filariases, paragonamiasis.
    
  • Viral: HIV
  • Fungal: Aspergillosis (especially ABPA), coccidiomycosis
    
• Allergy including asthma
  
• Medications
  
  • NSAIDS, allopurinol, phenytoid, semisynthetic penicillins, ASA
    
• Autoimmune disease
  
  • Churg-Strauss
    
• Addison's disease (usually low level)
  
• Cholesterol embolism
  

NB: from up to date: "Strongyloides can persist for decades without causing major symptoms. The infection elicits varying degrees of eosinophilia ranging from minimal to such high magnitude that it is mistaken for idiopathic hypereosinophilic syndrome."

Day #100 - Pleural Effusion/Empyema

Today we talked about the approach to pleural effusions:

1) How to do a thoracentesis

Pleural fluid can be mainly water (transudate) or exudative: blood (hemothorax), pus (empyema/complicated parapneumonic effusion), inflammatory, or chyle (chlothorax)

2) Light's Criteria for transudate vs. exudate

One of:

• Protein in pleural fluid >0.5 plasma
• LDH in pleural fluid >0.6 plasma
• LDH in pleural fluid >2/3 upper limit of normal in serum

False positive rate ~25%. Can measure SAPG (like SAAG) which if >12 suggests transudate. Do this if you had a low pre-test probablity of exudate.

This article discusses liklihood ratios for each value of these measurements and can be really helpful.

3) Management of complicated pleural effusion/empyema (great article here)

• • "The Sun Should Never Set of An Undrainded [Unsampled] Parapneumonic Effusion"
    
  • Sample the fluid at least
  • If >50% of lung has effusion, loculated, air-fluid levels, pleural thickening or pleural enhancement on CT highly suggestive that you will need drainage
  • Aspiration of frank pus, anaerobic smell, positive gram stain/culture, pH below 7.2, LDH >1000 imply you will need drainage
  • Drainage options include:
    
    • repeated thoracentesis
    • pig tail catheter (probably safer than surgical chest tube, less morbidity, but more likely to become clogged if frank pus. can also be inserted by seldinger technique with initial thoracentesis)
      
    • surgical chest tube (probably required for very thick, poorly flowing purulent material. higher morbidity than pig-tail)
      
    • VATS drainage: for failure of above, for patients with chronic empyema, ongoing sepsis, if need for decortication of "trapped lung"

Shameless self plug: here is my talk on the epidemiology of pneumococcal empyema.

Day #99 - PCP Pneumonia

Today we talked about a classic case of PCP pneumonia as a presenting illness for HIV.

Classically PCP presents with progressive dyspnea, usually initially with exertion then at rest, with dry hacking cough and fever. Classically the respiratory exam is relatively normal (sometimes there is a pleural rub) despite often remarkably abnormal chest x-ray. The classic x-ray, shown here, is of bilateral perihilar infiltrates.

LDH is usually elevated but can be normal in up to 10%. LDH can also be elvated in a number of other infections and malignancies.

Exercise induced desaturation is classic and one can do walking oximetry on their patients to see this effect.

The diagnosis is confirmed by direct calciflor stain or silver stain for organisms in the sputum, induced sputum, or BAL fluid.

There is some evidence that high resolution CT can be helpful in excluding the diagnosis and perhaps saving a bronchoscopy.

Treatment is ideally TMP/SMX (dosed 15mg/kg TMP component divided TID/QID) either IV or PO depending on status. Adjunctive steroids should be considered in patients who are hypoxemic on presentation (PaO2 <70,>35), who are in severe respiratory distress, or who have poor cardiopulmonary reserve. Ironically, this Toronto study showed that steroids did not influence outcome but did reduce septra intolerance. However, a cochrane metanalysis showed a NNT of 9 to prevent one death.

The use of HAART in acute PCP remains contraversial. You shouldn't stop someone's HAART if they are on it already (unless it is clearly failing); however, initiation of new HAART is unclear. Some studies show survival benefit, others mortality.

There have been many studies looking at prognostication. Obviously more severe disease at presentation is related to more adverse outcomes. This study found that age, previous history of PCP, treatment other than TMP/SMX, CMV PCR+ in the BAL, and previous use of PCP prophylaxis when diagnosed were all highly associated with mortality.

This simple prognostic score seemed to identify survivors from those who died.

I have previously written about HIV and cryptococcal meningitis here and here. These blogs link to the HIV treatment guidelines as well as the guidelines for the management of opportunistic infections.

Day #98 - Pneumonia

Today we talked about a case of pneumonia. I previously presented a case of pneumonia in "case of the week" back in July.

We stressed the management which includes:

Stabilize the patient:

• IV fluids, pressors if required, oxygen, mechanical ventilation if required. Early goal directed therapy.

Obtain microbiological specimens:

• sputum, blood culture, legionella urinary antigen if appropriate, other special tests as appropriatge
• pathogens most likely: streptococcus pneumoniae, haemophilus influenza, moraxella catarrhalis, staphylococcus aureus (including MRSA if risk factors), legionella, mycoplasma pneumoniae, chlamydia pneumoniae

Empiric antibiotic therapy (within 4h)

• Cover the most likely pathogens
• IDSA/ATS joint guidelines (are being revised to make more use of beta-lactams -- my suggestions include these guidelines and some new evidence)
• Healthy young person: macrolide (like azithromycin 500mg po x1 then 250mg po OD x 4d), beta-lactam like amoxicillin (1g po TID)
• Older, more ill:
• respiratory fluoroquinolone (like levofloxacin -- 750mg po Q24h x 5days)
• beta-lactam (ceftriaxone 1g IV q24, amoxicillin - high dose) plus macrolide
• MRSA: vancomycin (1g IV q12, renal dosed)
• Pseudomonas or other hospital acquired: Piperacillin-Tazobactam (4.5g IV q8h infuse over 4 hours) or Meropenem (1g IV q8h infuse over 4 hours)

Decision re: admission

• Prognostic score like PORT or SMART-COP.

Decision re: sending home

• Eating, drinking, mobilizing
• Off oxygen
• Ideally afebrile
• tolerating PO antibiotics
• Reliable follow up

Day #93 - Staphylococcus Aureus Bacteremia

Today we talked about a patient who presented with a febrile gastrointestinal illness who happened to have two diagnoses. First, a probable viral gastroenteritis acquired from his daycare aged son. Second, a concomitant staphylococcus aureus bacteremia.

I wanted to talk about the management of Staphylococcus Aureus Bacteremia. There is a good article here on the management of MRSA bacteremia.

• Never treat staphylococcus aureus in the blood as a contaminant. Like fungus in the blood, this always needs to be treated!
• The *minimum* treatment duration is 14 days (intravenous). This is for uncomplicated infections only.
  
  • Risk factors for complication:
    
    • Longer duration of illness
    • Community acquired infection
    • Persistent fever at 72h (OR 2)
      
    • Persistent positive blood culture at 96h (OR 5)
      
    • Hemodialysis patients
    • Indwelling lines or other prosthetic material
    • MRSA
    • No identifiable source for the bacteremia (i.e. no skin or line focus)
    • Blood cultures positive within 14 hours of drawing them
      
• You need to exclude bacterial endocarditis. Present in 10-13% of cases...
  
  • TEE is much more sensitive than TTE for making this diagnosis (103 patients with SA -- TEE dx endocarditis in 25%, TTE only found 7%). In patients for whom you are planning 14d therapy (particularly those who have risk factors for complication) you should probably not rely on a TTE to exclude IE.
• Can also cause pacemaker and AICD infections
• Vertebral osteomyelitis
• Septic arthritis
• Splenic abscess (persistant fever, LUQ pain)
  
• Septic thrombophlebitis (particularly with lines)
• Septic pulmonary emboli
  
• Brain abscess/meningitis/mycotic aneurysms
• Skin/soft tissue abscesses

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Treatment:

• Ideal treatment for MSSA is with a beta-lactam like cloxacillin or cefazolin. These are superior head to head with vancomycin for the treatment of MSSA.
• Removable foci should be removed if feasible and practical to do so
• Duration depends on complications. IE 4-6 weeks. Osteo ~6 weeks.
  

Risk of Death

• 20 to 40%!
• Age
  
• MRSA (OR 9.3)
• Blood cultures positive less than 12 hours (OR 7)
• Complication (OR 9)
  

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In medicine we often attempt to find one unifying diagnosis that explains all symptoms -- in satisfying what is known as Occam's Razor.

The important teaching point in a complicated case like this is that the patient may have multiple diagnoses and that we must keep an open mind. In response to Occam's Razor, Hickam's Dictum states that "[the patient] can have as many diseases as the damn well please".

Day #92 - "I don't know"

Wow. What a great case. It isn't often that I truly throw my hands up and say that "I don't know" but this was one of them.

But I hope the exercise in reasoning was useful for you. I think we demonstrated an approach that was safe, cost-effective, and broad in going through the history and physical exam.

Dr. Gold previously spoke about meningitis (bacterial) and that talk is available here.

In approaching a patient with multiple infarcts we need to consider the following differential:

• Emboli - Arising from the heart or great vessels. One possibility is subacute bacterial endocarditis, particularly given the history of night sweats. I think this patient needs blood cultures drawn with blind subculturing (endocarditis blood cultures) to look for unusual pathogens like brucella. I also think he needs a trans-esophogeal echo looking for a cardiac source including a bubble study to exclude PFO. This can also look at the aortic arch.
  
• Ischemia -- Either bad luck from uncontrolled risk factors, or genetic stroke syndrome like CADASIL, Fabry's or MELAS, or thrombophilia like antiphospholipid antibody syndrome, ATIII deficiency or hyperhomocysteinemia. I would exclude thrombophilia. As a last resort I would look into genetic testing. Night sweats don't fit with ischemia.
  
• Vasculitis (Night Sweats would fit with this too)
  
  • Primary:
    
    • Primary CNS angiitis
    • GCA/Takayatsu, polyarteritis nodosa (patient has Hep B!)
      
  • Secondary due to:
    
    • Infection:
      
      • Syphilis always needs to be considered in young patients who present with stroke like syndromes.
      • HIV can do this -- though he is suppressed.
        
      • CNS TB can cause this also (usually have CNS pleocytosis).
        
      • Fungal infections like cryptococcus can do this too.
        
    • Malignancy -- Angioinvasive lymphoma or lymphovascular lymphamatosis
      
• Other

If the echo is clean, I would consequently perform angiography (MRA possibly conventional) in this patient and look for evidence of vasculitis. I think given the night sweats and epidemiology that TB needs to be excluded prior to high dose steroids. I would repeat the lumbar puncture to ensure that it is still acellular (early TB can be acellular) and again send TB studies.

I would confirm whether or not he has had a mantoux. He should have one prior to immunosuppression anyways and should be treated for latent TB if this does not represent CNS TB.

I would probably scan his chest/abdomen/pelvis to look for evidence of malignancy, lymphoma or TB disease -- or something safer than the brain to biopsy and make a diagnosis.

Ultimately he may require a stereotactic brain biopsy to exclude TB and make a diagnosis. In a young man, with progressive infarcts and no other cause, I would discuss this with the patient.

TB is treatable, thrombophilia and emboli preventable, and lymphoma may be cured but CADASIL can not so we had better be sure!

Day #87 - Post Influenza Sepsis

This was one of my most memorable cases I presented to the discussant today. The article he asked me to send you is here.

Teaching Points:

• Influenza presents year-round but with a predominantly seasonal distribution. It is a highly transmissible virus with droplet (and possibly airborne particle) spread. Patients present with fever, malaise, lassitude, cough, myalgias, arthralgias and headache. The illness is usually self-limiting lasting approximately 1 week.
• Patients with underlying cardiac disease, respiratory disease, diabetes, or immunosuppression are at high risk of developing severe disease. Pregnant women, in the third trimester are also at risk compared to age-matched controls.
• Vaccines have been shown to have mortality and morbidity benefit, particularly amongst high risk groups. But vaccination of healthy individuals is proposed to have indirect benefit to these high-risk groups as well.
  
• A study done here in Toronto has shown that admitted patients with influenza, particularly those who are critically ill should be treated with oseltamivir. There is a reduction in mortality.
• Other notable sequelae:
  • Primary viral pneumonia or bacterial superinfection -- Most commonly streptococcus pneumoniae or staphylococcus aureus (including community acquired MRSA). This can be severe.
    
  • Viral myocarditis (rare)
  • myositis with possible rhabdomyolysis
    
  • Guillain-Barre syndrome, Influenza meningoencephalitis, Transverse myelitis

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In this case, the patient likely had a secondary bacterial infection with lobar pneumonia, sepsis and eventually multiorgan failure. Early recognition and treatment of sepsis is important. The principle is called "Early Goal Directed Therapy". This is a protocol of interventions designed to maximize tissue perfusion and interventions in a rational way.

Essentially this means:

• IV crystalloids to maintain central venous pressure of 8-12 (JVP 3-7cm is about that if you don't have a CVP line), normal blood pressure (MAP >=65) and mixed venous oxygen saturation of >=70%
• If still not at goal with crystalloids add vasopressors (i.e. norepinephrine)
  
• If still not at goal with this and hematocrit <30%,>
• If still not at goal with this, add positive inotrope dobutamine.
  
• Early appropriate antibiotic therapy
  
• Source control -- removal of septic focus, drainage of pus, etc --> this is often the neglected step....
  
• NB: pentastarch may be harmful and so I don't use it. The use of albumin is also contraversial -- an ongoing clinical trial hopes to solve this.
  

The protocol from Rivers et. al is below:

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Notable people affected by the 1918 pandemic:

• • Woodrow Wilson -- allegedly had meningoencephalitis while signing the treaty of Versailles
  • Harvey Cushing -- developed Guillain-Barre post-influenza
  • William Osler -- died of empyema (post influenza superinfection)
    

Day 85 - "That sounds bad"

Back pain is one of the most frequent complaints in medicine. Today's case highlighted why it always needs to be taken seriously.

Back Pain:

• Mechanical: Classically worsens with movement, better with rest. Can be referred down to bilateral hips, thighs.
  
  • Patterns:
    
    • Radiculopathy (classically sciatica): pain radiates in dermatome of nerve root impingement. May be associated with neurologic symptoms (weakness or numbness) in the affected area
    • Spinal Stenosis: pain radiates to legs. Worse with activity. Predictably improves with leaning forward, rest
      
  • RED FLAGS:
    
    • Night pain
    • B-Symptoms (fever, sweats, weight loss)
    • Neurological symptoms including numbness, weakness, bladder incontinence (overflow), fecal incontinence (loss of sphincter tone)
      
    • Known history of malignancy
      
• Inflammatory: associated with morning stiffness, aggravated by rest, possibly extra-axial symptoms of connective tissue disease.
• Referred pain

The examination should include a general exam looking for signs of systemic disease. A focussed exam should look for focal bony or paraspinal tenderness, and neurological findings (including rectal tone if appropriate), and associated MSK findings.

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In the case today the patient had progressive, severe back pain in the context of 2 months of B-symptoms. He presented with cord compression.

Differential:

• Malignancy:
  
  • Most commonly prostate, breast, lung. Then RCC, lymphoma and myeloma
  • Pain (present in 95%) is often the first symptom, usually preceeding neurologic symptoms by several weeks
  • Weakness (up to 85%) and sensory losses follow. Can also have bowel/bladder dysfunction and gait ataxia.
  • Patients should get steroids (dexamethasone 10mg IV x 1 then 16mg/day in divided doses tapered over 2 weeks), intravenous pamidronate, and either neurosurgery or radiation.
    
  • This trial showed that for metastatic disease in a single area, surgery +RT was superior to RT alone for solid tumors.
• Infection:
  
  • Spinal epidural abscess
  • Vertebral osteomyeltis including Pott's disease.
• Other:
  
  • Traumatic, vertebral compression fracture

Diagnosis is best made with MRI. If MRI is not an option, the next best test would be a CT myelogram.

Day #77 - Malaria

Today we talked about a case of a new immigrant to Canada who presented with cyclical fever and anemia. She had emigrated from a malaria endemic country and had had plasmodium malariae.

JAMA has a great article on malaria available here.

NEJM has a great article on malaria prevention available here.

Also, see my previous approach to anemia and thrombocytopenia.

Day #80 - Diarrhea

Today we talked about a case of acute diarrhea. The discussant took us through an excellent approach to acute diarrhea. Some highlights below:

Etiology:

• Infection (great article -- also IDSA diarrhea guidelines)
  
  • Viral: rotavirus, enterovirus, norovirus, etc. (CMV in immunocomprimized)
    
  • Bacterial: shigella, yersinia, e. coli, salmonella, campylobacter, C. difficile, TB (usually chronic), atypical mycobacterial (immunocomprimised)
    
  • Protozoal/Parasitic: Giardia, amebiasis, etc.
    
• Inflammatory
  
  • UC/Crohn's
• Ischemic
  
  • Small bowel -- pain out of proportion, post prandial pain
  • Large bowel -- bloody stool, colitis
• Osmotic
  
  • Laxatives, chewing gum diarrhea (xylulose), sorbitol, sucrose, post-surgical "dumping"
    
• Endocrine
  
  • Hyperthyroidism, carcinoid syndrome, VIPoma

Day #72 - Acute Cognitive Decline

We had actually discussed this case before in early August. At that time there were no myoclonic jerks, mri abnormalities, or eeg triphasic spikes suggestive of the diagnosis (now presumed) of CJD (from nejm or here from CID).



The previous discussion points on acute confusion, aphasia, and neurosyphilis are available here.

Day #70 - Fever of Unknown Origin III

I missed the rounds -- but have discussed pyrexia of unknown origin twice before. #1 and #2. Probably not as good as the discussant, but I referenced the article they were referring to.

"Special Guest Blog" by the discussant:

• Even in the "modern era", up to 1/3 of cases may go undiagnosed -these cases carry a good prognosis.
• Infections only account for 1/4 of all diagnoses.
• In certain cases without diagnosis, the benefits of liver biopsy outweigh the risks.
• Bone marrow cultures are of low diagnostic yield. Bone marrows should be performed only when there are other indications to do so ie unexplained cytopenias.
• I recently cared for a patient with FUO whose Hodgkin's disease was diagnosed on liver biopsy alone. Patients with FUO are challenging to investigate, are rewarding by virtue of the enigmatic causes that are may be found and reinforce the importance of basic principles like the careful history and physical examination.

Day #65 - Endocarditis

A confession -- today's case was "recycled" for your benefit -- and so is today's blog.

I have previously blogged on endocarditis, renal failure, and hyperkalemia and direct you to those sections.

Day #56 - Acute Monoarthritis Redux

We again approached this issue today.

The differential diagnosis of subacute-acute monoarthritis includes:

• Septic arthritis (gonococcal, non-gonnococcal bacterial, tuberculosis, fungal)
• Crystal (gout, pseudogout AKA CPPD, hydroxyapatate)
• Osteoarthritis flare

More rarely an acute monoarthritis can be a presentation of

• Seropositive and seronegative arthridities including reactive arthritis and post-streptococcal arthritis
• Hemarthrosis (in hemophilia and acquired hemophilia)

We use the history and physical to help us form an opinion on the etiology, but ultimately because septic arthritis is so damaging if missed, a synovial fluid analysis is required if there is suspicion of septic arthritis.

A previous blog discussed septic arthtiris and synovial fluid analysis.

Day #52 - Multiple possibilities...

Today we heard a very complicated case of a patient with known hematologic malignancy and a previous bone marrow transplant who presented with acute dyspnea, fever, and hypoxemia. The clinical exam was suspicious for congestive heart failure, in particular with RV overload/dysfunction.

We cast an appropriately wide net, thinking about a differential diagnosis that was most consistent with one/multiple of:

• Pulmonary Embolism
• Congestive Heart Failure
• Pneumonia

In medicine we often attempt to find one unifying diagnosis that explains all symptoms -- in satisfying what is known as Occam's Razor.

The important teaching point in a complicated case like this is that the patient may have multiple diagnoses and that we must keep an open mind. In response to Occam's Razor, Hickam's Dictum states that "[the patient] can have as many diseases as the damn well please".

Another important point is that while inelligant, in significantly ill patients who are awaiting a diagnosis empiric therapy for multiple conditions may be considered. In this case emperic broad-spectrum antibiotics (for example ceftriaxone + quinolone), treatment of CHF (lasix, nitrates as tolerated, ideally IV) , and empiric treatment for PE (based on our clinical suspicion, the high likelihood that a secondary event would be fatal, and the delay in being able to get a diagnostic test) were all appropriate. In this case, with unclear renal function, IV heparin is probably safer.

---

I alluded to the fact that the date of the allogeneic bone marrow transplant may be relevant to the differential diagnosis. The following figure from uptodate illustrates this point.

Early infections (pre-engraftment of the donor marrow) tend to occur with usual bacterial pathogens (gram positive and negative including pseudomonas), invasive candidiasis and aspergillosis, and herpes simplex and respiratory viruses.

Once the donor marrow has engrafted, the risk of non-encapsulated bacterial infections and decreases. However, the risk of encapsulated organisms and aspergillosis persists and the risk of more unusual opportunistic infections increases. These include CMV and other herpes viruses, toxoplasmosis, and PCP.

Later on, while the risk of VZV and EBV increases as well.

Day #49 - Cryptococcus and HIV Redux

2 cases of cryptococcal meningitis admitted in 1 week. This is somewhat unusual.

We have previously discussed HIV+Cryptococcus here.

We talked again about the management including:

(a) effective anti-fungal therapy (amphotericin B 0.7mg/kg) induction (14d +/- flucytosine) followed by consolidation with fluconazole 400mg x 10 weeks followed by maintenance with fluconazole 200mg until CD4 >200 x 6 months and

(b) effective management of increased ICP.

If OP >320mmH20 -- they should have aggressive management of ICP (serial LP to <200) or VP shunt

If OP >180 and symptomatic -- they should also have aggressive management

The OP should also be measured at the end of the 14d induction therapy.

---

FYI -- The US HIV guidelines are available here and here.

For the CC4s we will be discussing HIV again in seminar later this month.

Day #45 - Fever of Unknown Origin Redux

Today we discussed a very complicated (perhaps too complicated) case of a patient with fever of unknown origin, pancytopenia with granulomas in the bone marrow, probable disseminated intravascular coagulation, altered mental status and abnormal liver function.

The consultant, an infectious diseases specialist, went through a very broad differential diagnosis which I will attempt to re-create for you.

Non-infectious:

• Hematologic malignancy
• Non-hematologic malignancy (i.e. renal cell carcinoma)
• Venous thromboembolism
• Inflammatory:
  
  • Vasculitis -- i.e. temporal arteritis
  • Collagen Vascular Disease -- i.e. SLE
    
• Endocrine -- i.e. hyperthyroidism
• Periodic Fever Syndromes
• Factitious fever

Infectious:

• Viral:
  
  • HIV, EBV, CMV, influenza, measles/mumps, other.
• Bacterial:
  
  • Endocarditis, occult abscess, osteomyelitis from various pathogens
  • Unusual bacterial causes (see below)
    
• Fungal:
  
  • Endemic fungi such as:
    
    • Histoplasmosis (Ohio river valley, St. Laurence River Valley, Montreal in 1960s, Caves w/bats)
    • Blastomycosis (Northwestern Ontario)
    • Coccidiomycosis (Southwestern US)
• Mycobacterial
• Parasitic -- i.e. malaria (usually non-falciparum), babesiosis

---

Unusual bacterial causes

Some of these were discussed today:

• Rat-bite fever
• Meilodosis (travel to Australia, Southeast Asia)
• Plague
• Brucellosis (travel, exposure to sheep, cattle, goats, unpasturized cheese)
  
• Bartonella Henselae (Cat Scratch Disease)
• Q-Fever (Sheep, Pregnant Cats, high rates in Nova Scotia)

The key is the travel and exposure history and an open mind.

Day #44 - HIV

Today's case was a patient with HIV who presented with fever, confusion, headache, anorexia and malaise. His CD4 count was less than 100.

We discussed, based on the clinical features that the patient probably had a CNS infection of a indolent nature. The differential included toxoplasmosis, cryptococcosis, TB meningitis, syphilis, viral encephalitis or non-infectious causes like primary CNS lymphoma. The normal CT scan left cryptococcosus, TB meningitis, syphilis or viral encephalitis. The CSF studies confirmed cryptococcal meningitis, of which this was a fairly classic case.

The IDSA has guidelines for the management of cryptococcal meningitis, and this RCT in NEJM is probably the landmark study.

---

Remember in HIV there is a marked increase in the risk of certain infections:

• Any CD4 count: TB, pneumococcus, herpes simplex, varicella zoster
  
• CD4 less than 200 Pneumocystis Carini
• CD4 less than 100 Toxoplasmosis, Cryptococcus
  
• CD4 less than 50: CMV, Mycobacterium Avium Complex
  

We also talked about HIV treatment using the viral life cycle as a guide. In general, we initiate treatment if:

• The patient is ready to take the medication
• AIDS defining event OR
• CD4 >350 with rapidly decreasing CD4 and very high viral load
• CD4 less than 350 stongly consider starting
  
• CD4 less than 200 start
  

Using the viral life cycle, we talked about the various medications that are available:

• Viral fusion inhibitors (T20)
• Chemokine inhibitors CCR5 (miraviroc)
• Reverse transcriptase inhibitors (NRTI -- eg tenofovir, ermtrictabine/lamivudine, abacavir) and (NNRTI -- effavirenz)
• Protease inhibitors (lopinavir/ritonavir, atazanavir/ritonavir)
• Integrase inhibitors (raltegravir)

General rule: 2NRTI + PI or NNRTI in treatment naive, in experienced patients who are failing goal is to develop regimen which has 3 active drugs in multiple classes.

We discussed the "AIDS" defining criteria (CD4 less than 200 or specific conditions - see list). Guidelines for the management of HIV and opportunistic infections are available here.

Day #43 - Endocarditis

Today we discussed a great case of subacute bacterial endocarditis which presented as renal failure, uremia, and life threatening hyperkalemia. We discussed the approaches to altered level of consciousness and hyperkalemia. We also briefly discussed the approach to renal failure.

I wanted to touch upon the diagnosis of endocarditis. Endocarditis is a clinical and microbiological diagnosis which is established using epidemiologic criteria. The criteria are called the Modified Duke Criteria. They include:

Major Criteria

Microbiologic:
Positive blood cultures (>=2) with an organism that classically causes endocarditis (viridans group streptococci, staphylococcus aureus, enterococcus, HACEK organisms)
OR
Persistantly positive (>=3 or >=2 12h apart) for another organism

Echocardiologic:
Vegetation on valve not otherwise explainable or dehiscence of mechanical valve or abscess

OR

Clinical: *NEW* (not worsening) regurgitant murmur

Minor Criteria

• Predisposition -- known pre-existing valvular disease or IVDU
• Fever
• Evidence of vascular phenomenon -- septic emboli, mycotic aneurysm, Janeway lesions,
• Immunologic: glomerulonephritis (like this case), positive RF, roth spots, Osler nodes,
• Microbiologic: Blood culture not meeting major
• Echocardiographic not meeting major

Diagnosis: 2 Major, or 1 major 3 minor, or 5 minor

The ACC has updated guidelines on the management of valvular heart disease including endocarditis and endocarditis prophylaxis. These address the diagnostic algorithm and treatment in more detail.

Day #42 - Herpes Zoster (Shingles)

This morning we discussed a case of dermatomal vessiculobullous lesions in an immunosuppressed patient.

Differential diagnosis of vessiculobullous lesions::

• Herpes zoster
• Herpes simplex
• Bullous impetigo (staph/strep)
• Ecthyma gangenosum (gram neg esp pseudomonas)
• Hemorhagic bullous cellulitis (nec fasc, clostridial myonecrosis, vibrio
• vulnificus)

• Dermatitis herpeteformis
• Bullous skin diseases (eg bullous pemphigoid)

Treatment of herpes zoster (shingles):

Should be given to:

• Immunocomprimised patients
  
• V1 Zoster (Zoster Opthalmicus)
• Ramsey hunt syndrome
• Pregnant patients
• Age over 50 (decreases incidence of zoster associated pain)
  

Should be offered to all patients within 72h of lesions

Treatment options:

Disseminated Zoster (multiple non-contiguous dermatomes) or visceral/end organ involvement should probably be initially treated with IV.

Acyclovir 10mg/kg iv q8h (needs to be renal dosed, is nephrotoxic - need to keep extremely
well hydrated to prevent acyclovir crystals causing ATN)

Acyclovir 800mg po FIVE TIMES DAILY
Famciclovir 500mg po TID
Valacyclovir 1000mg po TID

Duration depends on clinical context. Non-immunosuppressed uncomplicated zoster - 7 days

The article on the zoster vaccine is here.

Day #38 - Invasive Pulmonary Aspergillosis

Today we talked about a case of a patient with acute myelogenous leukemia on chemotherapy who is presenting with febrile neutropenia.

In this case, the patient had a CT scan which had numerous pulmonary nodules with the so-called CT Halo sign (which is a nodule with ground glass haziness surrounding it). This led to the suspicion for an invasive fungal infection, the most commonly encountered in this population is invasive pulmonary aspergillosis.

If you are interested, you can email me and I will send you a copy of a talk I have given on IPA diagnosis and management.

The key to successful treatment is appropriate antifungal therapy and, if possible, recovery of the neutrophil count and reduction of immunosuppression. Treatment is "usually" for ~12 weeks or complete resolution of the clinical syndrome/lesions, whichever is longer.

Day #36 - Acute Confusion

Today we talked about a case of an elderly woman with an acute confusion. In approaching this problem, the history is important to exclude dementia which was sub-clinical for a long period but subsequently becomes obvious to the family.

We looked at a differential for an acute change in level of consciousness and the following general framework is helpful:

1. Drugs/Iatrogenic
2. Infection
   
   • Meningitis (bacterial, viral, TB, other -- e.g. cryptococcal, neurosyphilis)
   • Encephalitis (HSV1/2, HIV, CMV, WNV, Eastern Equine encephalitis, other)
   • Non-CNS infection with delerium
     
3. Metabolic
   
   • Electrolytes (hyper Ca, hypo/hyper Na, hypoglycemia)
   • hypothyroidism. B12/folate not usually acute.
     
4. Structural
   
   • Tumour
   • Bleed (SDH, SAH, ICH)
   • Other mass lesion
   • Epileptogenic focus (post ictal)
   • Stroke syndrome
   • Vasculitis
5. End-organ Failure
   
   • Cirrhosis (encephalopathy)
   • CHF
   • Respiratory -- Hypoxemia/Hypercarbia
   • Renal - Uremia
     

---

We then talked a bit about aphasias because the patient had anomia with a non-fluent aphasia and inability to understand.

Aphasias
1-naming-if normal - no aphasia
2-command-

DON'T UNDERSTAND
non fluent, no repeat - global aphasia
non fl - can repeat mixed transcortical
fluent - no repeating - wernikes
- can repeat - trans cortical sensory aphasia
UNDERSTAND
non fl--no repeat - brocas
non fl - can repeat - transcortical motor
fl - no repeat - conductive
fl - repeat - no name - nominal

---

We then entertained the possibility of neurosyphilis or a paraneoplastic syndrome such as paraneoplastic limbic encephalitis.

Neurosyphilis can present with a variable presentation.

"Early" <>

• asymptomatic
• meningitis (with cranial nerve palsies)
• meningovascular -- clinical picture of strokes, recurrent. Part of the differential for stroke in the young.
• otic syphilis -- tinnitus, vertigo, hearing loss
• occular syphilis -- uveitis, retinitis, vitritis
  

"Late" >10 years

• General paresis (of the insane):
  P - personality changes
  A - affect changes
  R - reflexes (hyper-reflexia)
  E - Eye (argyll-robertson pupils)
  S - Sensorium - delusions, hallucinations
  I - Intellect
  S - Speech (abnormal)
  
• Tabes dorsalis: sensory loss (dorsal columns), ataxia, bladder dysfunction, "lightning" pains in legs
  

Patients should have a positive RPR (though can be negative) and positive confirmatory test like the TPPA.

CSF should:

1. Have a positive VDRL (specific, but not sensitive)
2. OR Have a lymphocytic pleocytosis (WBC >20) and/or protein >500mg and positive peripheral serologies
   
3. Be suspected in positive CSF FT-ABs is positive

Day #31 - Fever of Unknown Origin

Today we discussed a case of true fever of unknown origin.

Epidemiologic Criteria:

• Fever x 3 weeks (38.3)
• Failure to find cause despite appropriate initial outpatient/inpatient investigations

Causes:

• Majority unknown
• Then infection (most commonly TB or occult abscesses), inflammatory, malignancy, other

Diagnostic tests (beyond initial):

• CT abdomen to look for abscess, lymphadenopathy, other pathology. Yield ~20%
  
• Bone scan (insensitive, but specific with good + LR)
• Liver biopsy -- regardless of hepatomegaly or LFT abnormalities has yield ~15%
• Temporal artery biopsy in the elderly -- yield ~ 15%
• Leg dopplers -- yield 2-6%
• Bone marrow biopsy-- in those with cytopenias or compatable syndromes. Yield ~1%

Meningitis

The meningitis lecture from today is available here.

Day #24 - Colitis

Today we discussed a gay male with fever, abdominal cramping, tenesmus and bloody diarrhea. The discussant made a very important point -- the clinical context and history are very important in making the diagnosis in acute colitis.

Before making the diagnosis of IBD one should exclude infections by history and special tests. Infections can mimic IBD clinically, radiographically, and endoscopically.

I wanted to talk about the differential diagnosis of bloody diarrhea with fever.

Differential Diagnosis

Infectious

• Enteroinvasive infection: Salmonella, Shigella, Campylobacter, E. Coli 0157:H7 (associated with HUS, frequently afebrile), Clostridium difficile, Klebsiella oxytoca
  
• Associated with receptive anal intercourse: HSV proctitis, gonorrhea, chlamydia (L serovar - AKA LGV/lymphogranuloma venerium), syphilis
  
• Associated with oral-anal practices or colonic irrigation: intestinal amebiasis
• More chronic, associated with the terminal illeum: intestinal tuberculosis
• Immunosuppressed patients: CMV colitis
  

Inflammatory

• Ulcerative colitis/Crohn's disease
  

Ischemic Colitis

There is also a good case of a patient with fever and diarrhea in the NEJM available here.

TGH "Case of the Week" July 14-18, 2008

30F with known HIV (CD4 unknown, not on treatment) presents with acute onset fever, chills, rigors, and cough with sputum. On exam she is febrile, tachycardic, hypotensive, hypoxemic on room air requiring hi-flow oxygen to maintain saturations >90% and in moderate respiratory distress.

The chest x-ray is taken and appears below:



Questions:

1) What is the most likely microbiological diagnosis?
2) What is the differential diagnosis?
3) What tests would you order to make your diagnosis?
4) What empiric treatment would you initiate in the ED?

BONUS: What "management strategy" would you employ in the ED and what journal was the study published in?

Thank you to the people who submitted answers. The "contest" is closed for this week. The winner will be notified in person.

"Answers"

1) The most likely etiologic agent to cause a lobar pneumonia in a patient with HIV is still streptococcus pneumoniae. In fact, patients with HIV are at an increased risk of getting pneumococcal infections and should all be vaccinated with the polysaccharide vaccine.

2) The differential diagnosis includes lobar pneumonia with the other organisms of community acquired pneumonia including haemophilus influenzae, moraxella cattharalis, and Staphylococcus aureus. Of particular concern in a patient who is rapidly deteriorating is community acquired MRSA necrotizing pneumonia.

Other causes would include Legionella pneumophillia and if risk factors such as underlying structural lung disease enteric gram negative organisms.

Upper lobe pneumonia should prompt concern for tuberculosis, although in this case the acquity and sepsis-syndrome argue more strongly in favor of bacterial pneumonia.

PCP tends not to be lobar and consolidative and the classic x-ray appearance looks more like bilateral peri-hilar interstitial infiltrates.

Fungal pneumonias like cryptococcal pneumonia, blastomycosis, invasive aspergillosis are unlikely and would not generally have this radiographic appearance and acute presentation.

3) Blood cultures should be sent ASAP (ideally before antibiotics) as they may be positive in up to 25% of cases of pneumococcal pneumonia. Sputum cultures should also be sent for conventional culture, legionella culture and TB culture. I would not recommend sputum for PCP in this case.

Urinary antigen detection for pneumococcal antigen is used in some centres (not here). Urinary antigen testing for legionella can help make this diagnosis.

CD4 testing in acute illness may not be helpful as the acute illness could cause a decrease in the counts; however, it would not be unreasonable as if the CD4 count was >200 rare causes are much more unlikely.

4) In a septic patient with community acquired pneumonia you need to cover broadly for the most likely pathogens. There are many ways to do this and in some cases what you choose will depend on recent antibiotic exposure.

In this case a combination of VANCOMYCIN 1gIV q12h and LEVOFLOXACIN 750mg IV/PO q24h would be appropriate. This would cover MRSA and quinolone resistant pneumococcus, the usual pathogens including the majority of pneumococcus, unusual pathogens like legionella, and many enteric gram negatives.

BONUS: The management strategy to be employed is "Early Goal Directed Therapy in Sepsis"

Day #18 - Cirrhosis

Today's case was of a 52 year-old man who presented with new diagnoses of cirrhosis with ascites, portal hypertension and probable variceal bleed who also had a new diagnosis of diabetes mellitus. The discussant showed us, although in his own uniquely tangential way, the type of clinical reasoning that great physicians use in arriving at a diagnosis.

There are a number of valuable teaching points today:

1) Ascites:

Etiology

• Elevated Hydrostatic Pressure --> CHF, constrictive pericarditis, Budd-Chiari, cirrhosis, IVC occlusion
• Decreased oncotic pressure --> malnutrition, nephrotic syndrome, protein losing enteropathy, cirrhosis/liver failure
• Increased fluid production in peritoneum --> infection (TB), neoplasm

Diagnosis on History/Exam
History

• Increased abdominal girth and ankle swelling are the most sensitive (greater than 85%)
• Past history of hepatitis or cancer are the most specific (greater than 85%)

Exam

• Not likely if no bulging flanks, no flank dullness and no shifting dullness
  
• Likely if fluid wave, shifting dullness, and peripheral edema (LR+3.8/-0.2)

2) Special Tests:

The team today also mentioned that they had performed a paracentesis in order to evaluate the ascites. This is important as paracentesis can:

1. Provide diagnostic clues
2. Exclude SBP

The Serum Albumin-Ascites Gradient (SAAG) is a valuable tool in deciding if the ascites is due to portal hypertension. SAAG = Serum albumin - Ascites Albumin. If <11 style="font-style: italic;">It should also be prevented in cirrhotic patients post GI bleed using TMP/SMX 1DS PO BID x 7d or CIPROFLOXACIN 500mg PO BID x 7d

The diagnosis can be made on the paracentesis:

• PMN >250 (LR + 6 LR - 0.2)
• WBC >1000 (LR + 9)
• Inoculation of blood culture bottles (fill them with required volume) can improve yield of the C/S

NB: In most cases, you do not need to use FFP/Platelets pre paracentesis.

Initial treatment is with CEFTRIAXONE 2g IV q24h with coverage narrowed to the culture data. You need only treat for 5 days.

Patients should get 1.5g/kg of 25% albumin within 6h then 1g/kg on day 3.

NB: Think of missed perforation if multiple organisms grow in the culture or if the WBC count in the fluid is much greater than 1000.

Day #8 - The Bacteremia that Won't Go Away

Today the discussant described evaluating for exit site and tunnel infections and differentiated these from catheter tip infections with bacteremia. We then talked about diagnosis and management of line-related infections focussing of a few specific pathogens. Here are a few take-away points:

One should obtain paired, labeled blood cultures from the periphery and line in question. The differential time to positivity can help determine whether the line is the source of the infection as follows

• Line and blood simultaneously positive suggests that the line is not the focus
• Line positive 2 hours before periphery suggests that the line is the focus
• Line positive and blood negative may suggest colonization only

In cases of Staphylococcus aureus, Pseudomonas sp., or Candida sp. unless there is some tremendously good reason to keep the line it should be removed.

• Failure to remove the focus/line can be associated with adverse outcomes including metastatic infection and death.
  
• Changing over a wire or reinsertion at the same side is not ideal but sometimes the only solution.
• If the line is not medically necessary and is easy to remove without complication it should probably be removed in most line related infections.
  

Treatment is then dependent on the presence or absence of metastatic infection and should be tailored to the organism and its sensitivities.

• One should be vigilant for evidence of metastatic infection or complications.
  
• Recurrent bacteremias with the same organism are highly suggestive of an occult/endovascular focus.
  

I will also take this moment to point out that for sensitive Staphylococcus aureus treatment with VANCOMYCIN is inferior to a BETA-LACTAM in the non-severly allergic patient.

---

We also talked about two interesting pathogens involved in this case:

• Staphylococcus lugdunensis which is a coagulase-negative staphylococci which has virulence similar to Staphyloccocus aureus and is a cause of endovascular infections such as native-valve infective endocarditis
• Achromobacter xylosoxidans ss xylosoxidans which is a rare gram negative rod which has been known to cause infections such as bacteremia and more rarely pneumonia, abscesses and meningitis. Patients with malignancies seem to be particularly at risk.
  

Decision making in Community Acquired Pneumonia

Read a great article published in CID on Aug 1, 2008. SMART-COP predicts people with CAP who will require admission to intensive care requiring ventillatory or vasopressor support. It does so better than the PORT score or CURB-65 which really only predict death.

Day #4 - Acute Monoarthritis

Today the discussant spoke about the approach to acute monoarthritis. It was a very articulate presentation and your participation was excellent.

To clarify the point on treatment:

• CEFTRIAXONE 2g IV q24h will cover most organisms including GC, most streptococci, Staph. aureus and many gram negatives. It is not the ideal agent for Staph. aureus, so if it turns out to be methicillin *sensitive* staph. aureus you should change to ANCEF (1g IV q8) or CLOXAILLIN (2g IV q6)
  
• Is MRSA a possibility or is this a prosthetic joint? --> ADD VANCOMYCIN (renal dose)
• Is there reason to worry about pseudomonas? --> I would suggest VANCO+CEFTAZADIME and ID consult.
  

• Prosthetic Joint = Call ortho. Probably should not be admitted to medicine if septic prosthetic joint is the main reason they are in hospital -- they need to go to the OR for wash-out and, in my experience, this is much less likely if they are admitted to GIM instead of orthopedics. Should get ID consult as well.
  

This article from JAMA is an excellent reference on making an evidence based diagnosis of septic arthritis on history, physical and laboratory examination.

VIDEO: How to do an arthrocentesis of the knee

Highlights include:

Risk Factors: Age, DM, rheumatoid arthritis, joint surgery, hip/knee prosthesis, HIV infection, skin infection, (unprotected sexual intercourse for GC)

History: Pain and swelling are present >80% of the time; fever is present only 60% rigors and chills less than that.

Synovial Fluid Exam (LR less than 0.1 rules out; LR >10 rules it in)

• WBC <=25,000 unlikely septic arthritis (LR 0.32) unless immunosuppressed
• WBC >=25,000 LR 2.9
• WBC >=50,000 LR 7.7
• WBC >100,000 LR 28

• PMNs <90%>
• PMNs >90% LR 3.4
  

Important to note that measurement of glucose, protein, lactate do not appear to be helpful according to the literature. Also note that LDH in the joint may have some utility in ruling out as LDH <250>