Recurrent spontaneous Escherichia coli meningitis in an adult: a case report

Abstract

Objectives: The aim of this study was to characterize an unusual case of spontaneous, community-acquired Escherichia coli meningitis in an adult presenting to a general hospital in Kenya, where initial clinical recovery was followed by reinfection with an MDR, hospital-acquired strain.

Patient and methods: An adult presented to a hospital in Kenya with meningitis symptoms. E. coli was cultured from CSF. Treatment with ceftriaxone was successful; however, the patient relapsed a few days later. E. coli was cultured from CSF and blood during the reinfection episode, though the patient died during admission. We sequenced the isolates using Illumina MiSeq and performed antimicrobial susceptibility testing, fitness and virulence assays on the bacteria.

Results: The E. coli isolates from the two episodes were found to be distinct: the initial strain was ST88, serotype O8 H17 while the subsequent episode was caused by an ST167, serotype O101 H5 MDR strain. The ST88 strain was susceptible to all drugs except ampicillin and amoxicillin/clavulanate while the ST167 strain was MDR, including to all β-lactam drugs due to the presence of the carbapenemase gene bla _NDM-5. The hospital-acquired ST167 strain was also resistant to newer drugs such as cefiderocol and eravacycline, which are currently not available locally, and had overall lower fitness and virulence in vitro compared with the initial infecting strain.

Conclusions: Though less fit and virulent in vitro, the MDR strain was fatal, suggesting that host factors, rather than bacterial virulence, may have been of greater importance in this patient's outcome.

Figure 1.

Growth curves of E.coli meningitis strains in standard and salt supplemented (5% w/v) LB media. Carbapenem-susceptible E. coli strain from CSF, ECO-1 (filled triangle), and carbapenem-resistant strains from CSF, ECO-2 (filled circle) and blood, ECO-3 (filled square) were grown at 37°C and OD₆₀₀ measured at 30 min intervals. The strains were grown in triplicate on three separate days with the mean plotted and error bars indicating SD.

Figure 2.

Survival of carbapenem-susceptible and resistant E. coli strains in healthy human serum. Strains were incubated in 40% pooled normal human serum at 37°C for 3 h. Aliquots were taken every 45 min and colonies enumerated by plating. Three separate experiments were performed for each isolate and the mean and SD (error bars) plotted for each strain.