Abstract:
Pediatric meningitis is a global health problem, with insufficiently known pathogens and antibiotic resistance (AMR) especially in low-resource settings. Here, we sought to uncover the virulence and AMR of pathogens associated with infant meningitis, treated with ceftriaxone, in Kampala, Uganda. In a bid to isolate Klebsiella oxytoca, we coincidentally recovered a co-culture and challenged it with antibiotic susceptibility testing (AST) on a panel of 14 antibiotics. We then combined metagenome binning with antiSMASH/PRISM genome mining to unveil the pathogens, their virulence and molecular targets in relation to meningitis. From AST, the co-culture exhibited resistance to multiple aminoglycosides, fluroquinolones, and β-lactams, including ceftriaxone, the inherently used drug. From metagenome annotation, the first bin was identified as Pseudomonas
aeruginosa ST242 and the second as Klebsiella michiganensis ST*1b23. Among others, P. aeruginosa ST242 virulence factors include type 3 and type 6 secretion systems, biofilm, and nonribosomal peptides (NRPs) of the pyoverdine synthase operon, targeting claudin-5, a component of the tight junctions of the blood-brain barrier (BBB). The P. aeruginosa ST242 genome portrays intrinsic resistance to beta-lactamases (blaOXA-50 and blaPAO), aminoglycosides [aph(3′)-IIb)], fluoroquinolones (crpP), tetracycline (tmexD2) and fosfomycin (fosA), among others. From K. michiganensis ST*1b23 genome mining we elucidated a yersiniabactin-related metabolite, targeting the ligand-binding domain of the human polymeric immunoglobulin receptor (pIgR) and other components of the BBB. The K. michiganensis ST*1b23 chromosome encodes the genes blaOXY-1 and OqxA/B, conferring resistance to β-lactams, fluoroquinolones, and trimethoprim respectively. Notably, we found one frameshift and nine substitution mutations conferring carbapenem and cephalosporin resistance mechanisms. Overall, our findings strongly suggest coinfection and a mechanistic crosstalk between P. aeruginosa ST242 and K. michiganensis ST*1b23 in the pathogenesis of meningitis in this case. Importantly, ceftriaxone could be an inappropriate treatment choice for these pathogens. Hence, serious surveillance and experimental studies will improve the management of pediatric meningitis
