In vitro subminimum inhibitory concentrations of macrolide antibiotics induce macrolide resistance in Mycoplasma pneumoniae.

AIM: This study aims to investigate the inducing effect of subminimum inhibitory concentrations of macrolide antibiotics on Mycoplasma pneumoniae (M. pneumoniae) resistance to drugs.

MATERIALS AND METHODS: One M. pneumoniae reference strain M129 (ATCC 29342) and 104 clinical isolates were incubated at 37C for 6-8 days. Genomic DNA of M. pneumoniae was extracted using TIANamp Bacteria DNA kit and amplified by polymerase chain reaction (PCR).

RESULTS: Ten sensitive isolates obtained from 104 M. pneumoniae clinical isolates were induced by subminimum inhibitory concentrations of macrolide antibiotics. Among them, three were found to possess mutations in L4 and L22 ribosomal proteins. Two cases carried simultaneously the C162A and A430G mutations of L4 and the T279C mutation of L22. In addition, one case had only the A209T mutation of L4.

CONCLUSIONS: Repeated in vitro exposure to subminimum inhibitory concentrations of macrolide antibiotics could induce selective mutations in ribosomal genes of M. pneumoniae clinical isolates that cause resistance to macrolide antibiotics. Hippokratia 2015, 19 (1): 57-62.