Presence of the blaTEM Gene in Commensal Neisseria spp.: A Possible Cause for the Acquired Drug Resistance Among Pathogenic Respiratory Bacteria.

Abstract

Background The oral microbiome consists of various bacterial genera, withNeisseriaspp. being a prominent part of this niche. WhileNeisseria gonorrhoeaeandNeisseriameningitidisare human-restricted pathogens, non-pathogenicNeisseriaspecies likeNeisseria sicca,Neisseria perflava, etc.,are primarily commensals that can also behave as opportunistic pathogens. With increasing penicillin resistance in commensalNeisseria, there is a concern that these bacteria might harbor resistance genes that can be transferred to other pathogens. This study aimed to characterize the blaTEM gene (encodes for the plasmid-mediated β-lactamase enzyme that hydrolyzes the β-lactam ring) of commensalNeisseriaspp. isolated from respiratory samples. Methodology The research was conducted in the Department of Clinical Microbiology at Sri Ramachandra University, Chennai. The specimens used were sputum and throat swabs, which were subjected to a series of phenotypic methods and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) for speciation. The antibiogram was determined using the Kirby-Bauer disk diffusion method, and a PCR assay was utilized to identify theblaTEMgene responsible for β-lactamase production. Results Out of 274 processed samples, 65 unique commensalNeisseriaspp. were identified. The study highlighted the presence of theblaTEMgene in 93.9% (61) of the isolates, which is responsible for β-lactamase production. All isolates exhibitedresistance to penicillin. MostblaTEM-positive commensalNeisseria spp. were susceptible to cefuroxime (83.6%), ceftriaxone (85.2%), and cefotaxime (85.2%). The high prevalence of theblaTEMgene in commensalNeisseriais alarming. The gene, found on plasmids, could potentially transfer to other related species likeNeisseria gonorrhoeaeandNeisseriameningitidis, as well as other Gram-negative bacilli. Conclusion The presence of resistance genes in commensal bacteria is of concern, as they might be reservoirs for resistance transfer to pathogenic strains. The study emphasizes the importance of continuous monitoring and deeper investigations into commensal bacteria, emphasizing the need for a broader community screening approach to understand resistance mechanisms in the normal microbiome.