CSF: Serratia marcescens  – Shipped February 11, 2019


A simulated CSF sample collected from a 42 year-old patient with a CSF shunt in place was sent to category A laboratories.

Participants were expected to report Serratia marcescens and to report antimicrobial susceptibility testing (AST) results.



  1. The isolation of an uncommon pathogen, such as Serratia marcescens or another species of Enterobacterales, from the CSF of a patient with a history of shunt placement suggests contamination of the distal end of a ventriculoperitoneal (VP) shunt due to bowel perforation, peritonitis, hematogenous seeding, or contamination of an externalized device (i.e., external ventricular drain [EVD]).
  2. AST should be performed with only relevant antimicrobial agents for isolates growing from CSF samples. The reporting of antimicrobial agents contraindicated for the treatment of CNS infections has the potential to result in patient harm.

Full critique (PDF)

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