Capnocytophaga canimorsus Meningitis – Diagnosis with 16S rDNA PCR when Conventional Methods Failed to Identify the Causative Agent

Anurup Kumar

doi:10.31579/2693-4779/025

Abstract

Meningitis whether bacterial or viral, poses many challenges to clinicians as the causative agent is often not found. According to guidelines, it is standard to start empiric treatment before a Cerebrospinal Fluid (CSF) sample is obtained. Meningitis, if not diagnosed and treated early, can lead to high morbidity and mortality rates with serious neurological sequelae. While the most common cases of bacterial meningitis are related to Streptococcus pneumoniae and Neisseria meningitidis, this clinical case report found a rare case of meningitis caused by a zoonotic pathogen, Capnocytophaga canimorsus; a commensal found as part of the normal flora of dogs and cats. This rare organism was identified with the help of broad range 16S ribosomal DNA Polymerase Chain Reaction (rDNA PCR), an emerging technique that is now increasingly useful in rapid diagnosis especially if the offending agent is not timely identified and conventional methods have failed, making diagnosis and management difficult for physicians.

Highlights

EpidemiologyCapnocytophaga canimorsus is a rare species that causes severe and often fatal infections in humans
While the most common cases of bacterial meningitis are related to Streptococcus pneumoniae and Neisseria meningitidis, this clinical case report found a rare case of meningitis caused by a zoonotic pathogen, Capnocytophaga canimorsus; a commensal found as part of the normal flora of dogs and cats
This rare organism was identified with the help of broad range 16S ribosomal DNA Polymerase Chain Reaction, an emerging technique that is increasingly useful in rapid diagnosis especially if the offending agent is not timely identified and conventional methods have failed, making diagnosis and management difficult for physicians

Summary

Background

Capnocytophaga canimorsus is a rare species that causes severe and often fatal infections in humans. Some resistant strains of Capnocytophaga that produce class D beta-lactamase respond well to Clindamycin [19] This clinical case report a case of meningitis caused by C. canimorsus in a woman with no known risk factors, in whom 16S rRNA gene sequencing aided identification of the pathogen, when conventional methods like culture and quantitative PCR failed. To check for response to treatment, a third CSF analysis was undertaken, the results of which were reassuring By this time Microbiologist alerted us that the causative agent had been identified to be Capnocytophaga canimorsus via broad range 16S rDNA PCR technique. The patient was discharged following successful treatment and has been referred for a follow-up in ENT for her hearing impairment and Neurology clinic for her on-going chronic issues with balance This was believed to be a consequence of her previous brain bleeds and cerebellar atrophy which had worsened due to the acute infection. She preferred to go to a private facility for a period of rehabilitation following her discharge and has remained well

Discussion

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Conclusion