CMI Highlight: Prevalence of antimicrobial resistance genes in Bacteroides spp. and Prevotella spp. Dutch clinical isolates
Veloo et al., studied the prevalence of resistance genes in two important anaerobic genera, Bacteroides and Prevotella, was assessed by applying PCR specifically directed to genes of interest. Read more
A total of 101 Bacteroides spp. and 99 Prevotella spp. human clinical isolates were identified using MALDI-TOF MS. The presence of the resistance genes cfxA, cepA, cfiA, tetQ, ermF, and nim, was evaluated. The prevalence of resistance genes was compared to phenotypic resistance to amoxicillin, clindamycin, meropenem and metronidazole.
Even though the majority of the Bacteroides isolates (92.1%) showed resistance towards amoxicillin, only 52/101 of the isolates harbored one of the resistance genes, accounting for this resistance. Within the genus Prevotella the presence of cfxA (50/99) almost perfectly matches the amoxicillin resistance (48/99). No difference in prevalence of the ermF gene (16/101 and 9/99) and clindamycin resistance (16/101 and 10/99) was observed within Bacteroides and Prevotella, respectively. Two isolates of Prevotella were resistant for metronidazole. One harbored the nim gene. One metronidazole susceptible isolate of Bacteroides harbored a nim gene. Within the Bacteroides and Prevotella genera, 6/101 strains and 5/99 isolates harbored three different resistance genes, respectively, among them tetQ. TetQ is often located on a conjugative transposon, increasing the chance of horizontal gene transfer between isolates.
The author unraveled an unknown mechanism in Bacteroides non-fragilis isolates causes resistance to beta-lactam antibiotics.
Veloo et al. Showed that the prevalence of the tetQ gene among Prevotella is increasing and the existence of isolates harboring three resistance genes which is a worrying development.