Bilateral leg 'cellulitis'

A number of consults for this clinical entity today makes me want to provide you with this excelllent review of the mimickers of cellulitils.... The most common mimicker I see is venous stasis dermatitis, often bilateral, in the obese patient with heart failure.

Peripartum sepsis with Group A Streptococcus

Today we saw a case of group A streptococcal bacteremia associated with peripartum sepsis and intrabdominal abscesses. This is similar to a case reviewed here (and here). NEJM case report here.

The case definition (epidemiologic) for streptococcal toxic shock syndrome (CDC) includes:

• hypotension defined by a systolic blood pressure less than or equal to 90 mm Hg for adults
  
• Multi-organ involvement characterized by two or more of the following:
• Renal impairment: Creatinine greater than or equal to 2 mg/dL (greater than or equal to 177 µmol/L) for adults. In patients with preexisting renal disease, a greater than twofold elevation over the baseline level.
• Coagulopathy: Platelets less than or equal to 100,000/mm3 (less than or equal to 100 x 106/L) or disseminated intravascular coagulation, defined by prolonged clotting times, low fibrinogen level, and the presence of fibrin degradation products.
• Liver involvement: Alanine aminotransferase, aspartate aminotransferase, or total bilirubin levels greater than or equal to twice the upper limit of normal for the patient's age. In patients with preexisting liver disease, a greater than twofold increase over the baseline level.
• Acute respiratory distress syndrome: defined by acute onset of diffuse pulmonary infiltrates and hypoxemia in the absence of cardiac failure or by evidence of diffuse capillary leak manifested by acute onset of generalized edema, or pleural or peritoneal effusions with hypoalbuminemia.
• A generalized erythematous macular rash that may desquamate.
• Soft-tissue necrosis, including necrotizing fasciitis or myositis, or gangrene.

In the context of a microbiologic diagnosis for group A streptococcus in a sterile site = confirmed STSS. Colonization of GAS or non-sterile site isolate = probable STSS.

Treatment includes supportive care, debridement of necrotic/non-viable tissues and source control , consideration of IVIG , and antibiotic therapy with beta-lactam (i.e. penicillin) with clindamycin (for its anti-ribosomal activity and effect on non-log phase growth); however, recent data suggests that exotoxin production may actually be increased if the organism is clindamycin resistant. Linezolid may be an alternative anti-ribosomal agent in this case.

Candidemia redux

See previous blog. Today we saw a patient with candidemia, presumably from a urinary source. We discussed species identification, and the use of the germ tube test for rapid identification of Candida albicans.

This article discusses the clinical utility of the germ tube test, quoting a sensitivity of 87% and specificity of 100% for identifing C. albicans -- directly off of the positive blood culture! This saves ~24h in the rapid identification of C. albicans, as the germ tube is traditionally performed off a subculture on fungal medium, adding up to a 24h delay.

Strongyloides

Previously mentioned 'strongy' here. CMAJ reviews here, and here.

There was an extensive discussion at case-rounds yesterday afternoon about prophylaxis for strongyloidiasis in patients at risk who will be immunosuppressed.

Here is a review of strongyloidiasis in the immunocomprimised patient.

This article discusses prevention in patients with connective tissue diseases.

In patients with bone marrow transplantation or solid organ transplantation recent guidelines suggest that patients with unexplained eosinophilia or who have lived/travelled in areas endemic for strongyloidiasis, even if remotely, should be screened prior to transplant with stool O&P time three and serology. Positive screening or eosinophilia should prompt pre-emptive treatment prior to transplant with ivermectin. Mind you, some experts would suggest, given the few side effects, that people who have lived in endemic areas should just be treated...

Recent case report of death due to strongyloides in patient with HSCT...

TB - Tuberculosis Hodge-podge

Yesterday we saw an interesting case at the end of the day of a patient on immunosuppression who presented with a new left sided pleural effusion and some parenchymal changes compatible with a flare of her underlying lung disease vs. tuberculosis.

This patient comes from an endemic country and has evidence of fibronodular changes on chest x-ray (RR for reactivation ~15). There has been no previous TB treatment.

This highlights a large number of good teaching points:

1. Diagnosis and management of latent TB.
2. Diagnostic approach to possible TB pleuritis.
3. The interplay between TB and TNF-alpha inhibitors.
4. The radiographic manifestations of TB and the differences in immunosuppressed hosts.
5. The yield of bronchoscopy in patients who are not coughing.
6. The potential role for gastric aspirate to make the diagnosis

FYI - Canadian Tuberculosis Standards (Guidelines) available for free here.

Streptococcus milleri group

Today we reviewed a case of multiple soft tissue abscesses caused by an organism of the Streptococcus milleri group.

This group of organisms includes:

• S. anginosus
• S. intermedius
• S. constellatus

Because of phenotypic similarities, exact speciation can be difficult without more advanced means of testing. Speciation matters as intermedius and constellatus are very frequently associated with abscess formation; wheras anginosis is not. The clinical presentations of the various species are discussed in this CID article. Soft tissue abscesses are most common, followed by pleuropulmonary (including empyema), intrabdominal (including liver abscess), and brain abscesses.

The propensity to form abscesses may be related to impaired neutrophil chemotaxis and resistance to destruction when phagocytosed.

Treatment involves adequate surgical source control, and antibiotics, usually parenteral beta-lactams such as Penicillin G if the isolate is susceptible. Duration of therapy varies depending on location of abscess and adequacy of surgical drainage.

Staphylococcal bacteremia

Am back on clinical service today! So, I will begin to blog again...

Today we discussed Staphylococcus aureus bacteremia including MRSA. I have previously blogged about this here -- with links to what I believe are the relevant articles.

I will add this article from CID which discusses combination antibiotic therapy in MRSA infections.