Sunday, May 02, 2010

Nosocomial bacterial meningitis pearls

Van de Beek et al.  NEJM 2010; 362: 146-154.  Current Concepts.  Review article.

1.  Post craniotomy, one third of cases occur in first week, one third in second week, and one third after second week, up to "years" after craniotomy.  The incidence is 0.8-1.5 %.

2.  Internal ventricular catheter infection causes infection 4-17 % of time.  Colonization at time of surgery is the most important cause, and most cases occur within one month.

3.  External ventricular catheter shunts has an 8 % incidence of infection with a sharp rise after five days.  Article suggests no reason to remove a catheter just because 5 days has elapsed.

4.  CHT usually has a basilar skull fracture if infections occur.  This is most common cause of recurrent meningitis.

5.  Gram staining and culture are hallmarks of diagnosis and measurement of cells and diff may be falsely negative in many cases. especially ventricular catheters.

6.  Post neurosurgery, a CSF lactate level of > 4 mmol/L has a sensitivity of 88 %, specificity of 98 %, PPV of 96 %, and a NPV of 94 % for bacterial meningitis.  However, one review suggested many cases would be missed with this cutoff.

7.  Antibiotics postop or post head injury should be vancomycin plus ceftazidine, cefepime, or meropenem.  Goal should be serum trough of 15-20 for vancomycin.  In intraventricular therapy, close the drain for an hour after the first dose.  The trough should equal ten times the MIC of the antibiotic to sterilize the CSF. 

8.  External lumbar catheter infection rates have been reported between .8 and 5 percent.  After LP infection rate is one in 50,000 with 80 cases per year in US. 

9.  Acinteobacter is more common in nosocomial infections that may be resistant.  Initially may use iv meropenem, with or without intrathecal or intraventricular aminoglycoside, if resistant use colistin or polymyxin B.  Colistin in one study sterilized 13/14 patients and cured those.  In another study, all patients treated with colistin survived.