A case report to increase awareness of the accuracy of different methods for the identification of Listeria monocytogenes

Abstract

Listeria monocytogenes, is a Gram-positive facultative intracellular bacterium without spores. It can cause invasive diseases such as septicemia, meningitis, and encephalitis, and has a high mortality rate. This is a report on a recent case of neurolisteriosis isolated from cerebrospinal fluid sample of a patient with diabetes and chronic heart failure in our hospital. The patient initially received the combined treatment of cephalosporin and meropenem (both 1.0 g every 8 hours). We identified the pathogenic organism as L. monocytogenes using three identification methods: mass spectrometry, biochemical assays, and molecular techniques. After determining the pathogenic bacteria, we quickly informed the clinician and suggesting a change in antibiotic treatment and immediately discontinued cephalosporin and meropenem. The patient's symptoms were significantly improved after 9 days of penicillin G treatment, and the patient chose to be discharged for personal reasons. In conclusion, certain strains of wild-type Listeria monocytogenes can lead to identification errors that occur across platforms and methods.

Keywords

• Listeria monocytogenes
• Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
• Cerebrospinal fluid
• Intracranial infection
• 16S rRNA
• Case report