Recurrent HSV Encephalitis

Interesting case. Second episode of Herpes Simplex encephalitis in an adult approximately 3 years after the first. Here is a case report and literature review on recurrent disease.

The main deteminant of outcome in HSV encephalitis is time to acyclovir. This article discusses factors associated with the delay of administration.

This article discusses the outcomes of HSV in population based study.

I discuss viral encephalitis in a previous blog.

Neutropenic Entercolysis

With thanks for the suggestion.

Today we saw a patient with lymphoma, status post bone marrow transplant, who developed fever, neutropenia, abdominal pain, diarrhea and colitis on CT scan with a presumed diagnosis of neutropenic enterocolitis.

This condition, loosely defined (but best defined as fever, abdominal pain and colonic thickening -- see here) is seen in about 5% of patients. The mortality approaches 50% in some studies.

Ultrasound may be useful in screening for this condition early on.

Usual pathogens are bacterial (gram negative bowel flora including pseudomonas, and gram positive bowel flora). Bacteremia is seen in 35-80% of cases. A reasonable coverage choice would be an anti-pseudomonal beta-lactam (i.e. piperacillin-tazobactam or meropenem) with anerobic activity, or something like ceftazadime with metronidazole.

Fungal infection is rare (~5%) and usually candidal, but caries a high mortality (~80% in some studies). Emperic antifungal coverage should be considered if still febrile and neutropenic at 5 days or in the severely ill.

Critically ill patients should be considered for colectomy as should patients with complications (megacolon, perforation).

Enterococcal Endocarditis

We saw a case of aortic and mitral valve enterococcal endocarditis.

Previous endocarditis blogs here with associated links.

While not really studied, there are some limited case reports or in vitro data for the possibility of:

• Daptomycin (also retrospective review in bacteremia here)
  
• Linezolid (and in general review of linezolid in IE here)
• Ceftobiprole (NB it lost its FDA approval in April 2010!)
  

Other options are reviewed here.

Though any of the above agents should primarily be used in the context of clinical trial or 'dire cicrumstances'

Strongyloides - The saga continues

We discussed strongyloidiasis at length again today.

See previous blogs on 'strongy' here and a previous blog on eosinophilia here.

Epidural Abscess

We have seen a number of cases of epidural abscess this week. Reviews here (Lancet Neurology), and here (NEJM). Not to be confused with the coolest name in medicine Pott's puffy tumour as described here.

Epidemiology:

• Rare - about 0.2 to 2 per 10,000 admissions
• Often underlying condition:
  
  • Diabetes
  • Alcoholism, Injection Drug Use
  • HIV
  • Chronic spine disease
  • Previous spine surgery
  • Indwelling catheters

Pathogenesis:

• Contiguous spread of infection from soft tissue/vertebrae/manipultion (~30%)
• Hematogenous seeding ~50%
• Unknown 15%
• Can injure spinal cord leading to paralysis due to compression (local) or small septic emboli causing infarction.

Microbiology:

• Most ~60% are Staphylococcus aureus including MRSA
  
• Can be CNST if hardware in situ
• E. coli from bacteremic urinary tract infection
• Pseudomonas (often injection drug use)
• Other: enterococcus, viridans group streptococcus, mycobacteria, fungus (candida, other) etc.

Diagnosis:

History:

• Pain is common, initially localized, then radicular and referred (85%)
  
• Increasing weakness as cord is involved and sensory loss
• Bladder and bowel involvement occur later then fullparalysis
• Fever may be absent! Especially if NSAIDS or acetominophen for pain

Labs:

• Normal WBC in up to 40%!
• Most have elevated CRP and ESR
  
• Bacteremia in up to 60%

Imaging:

• MRI is test of choice.
  
• Concomittant osteomyelitis seen in ~80%. This may be seen on CT; but the abscess can be missed with plain CT.

Treatment:

• If stable and no imminent neurologic comprimise, it is best to get a definitive diagnosis. Blood cultures should be sent and operative specimens. Then antibiotics can be started tailored to the etiologic agent.
• Usually combined medical and surgical management is required. The deficits can progress exceptionally quickly (i.e. complete paralysis within hours) and can be irreversible (particularly if paralysis has been for more than 36 hours!
• If empiric coverage is required, coverage for Staphylococcus aureus, including MRSA as well as gram negatives should be started. Antipseudomonal coverage may be required if there is a risk for pseudomonas -- i.e. IDU, known pseudomonas elsewhere.
  
  • One reasonable approach would be to start VANCOMYCIN (MRSA) and either CEFEPIME, PIPERACILLIN-TAZOBACTAM, or CEFTAZADIME

Common pitfalls - See figure from NEJM below:

Prognosis:

• Paralysis will develop in 4-22%. Paralysis is likely to be irreversible after 24-36 hours
• With prompt surgery most patients have as good or better neurologic status than they did before the OR.
• Death does occur in about 5%
  

MRSA pneumonia

Today we saw a case of severe methicillin resistant staphylococcus aureus (MRSA) pneumonia (review). In the era of community acquired (CA-MRSA), this is becoming a significant problem.

Management includes:

• Supportive care in keeping with best practices
• Vancomycin is the 'gold standard' -- but not a great one.
  
  • aim for trough ~ 20
  • avoid in MIC greater than or equal to 2 (and maybe even 1)
    
  • addition of rifampin improves short term microbiologic cure, but interestingly was associated with increased long term mortality
• Alternatives include:
  
  • Linezolid -- often postulated, not yet proven to be superior.
    
    • the maker of linezolid was fined for off label marketing of the drug for the use in MRSA pneumonia (see one example news article here) so caveat emptor...
  • Tigecycline -- theorhetically 'better' lung kinetics than vancomycin -- not studied
  • Ceftobiprole -- under study. Has advantages in terms of tissue penetration and the fact that it is a beta-lactam
  • doxycycline or TMP/SMX -- could be an option for milder disease.
  • Daptomycin -- do not use, inferior.
• Duration of therapy 8-14 days (or longer in bacteremia with other focus) depending on resolution of clinical symptoms. Some studies show no difference between 8 and 15 days of therapy. Many experts 'prefer' 14 days.
  

Necrotizing Fasciitis

Today we saw a case of necrotizing fasciitis (see previously blogged). This case was in the abdominal wall and perineum of a female patient with obesity and diabetes, and is likely polymicrobial (type I).

While people often use 'Fournier's' gangrene to infer disease in males that involves the scrotum, the disease entity, involving the pereneum does occur in women. In fact, women seem to have higher mortality, possibly because of involvement of the retroperitoneal space due to anatomic differences and also due to delays in diagnosis. This article also suggests that disease in females is underrecognized, and that ano-rectal disease is far more dangerous precipitant than urological disease.

Death and amputation are more likely at extremes of age, with advancing comorbidities (including diabetes), with sepsis, and with visible gangrene on presentation.