Chua Teck-Phui, Danielewski Jennifer, Bradshaw Catriona S, Machalek Dorothy A, Garland Suzanne M, Huaman Jose L, Jensen Jørgen S, Murray Gerald L
Department of Obstetrics, Gynaecology, and Newborn Health, University of Melbourne, Parkville, Victoria, Australia.
Centre for Women's Infectious Diseases, The Royal Women's Hospital, Parkville, Victoria, Australia.
J Antimicrob Chemother. 2025 Jul 1;80(7):2044-2050. doi: 10.1093/jac/dkaf174.
Mycoplasma genitalium is a sexually transmitted bacterium of increasing concern due to issues around antimicrobial resistance. Resistance is typically mediated by SNPs; however, the difficulty of isolation and culture of M. genitalium limits the ability to analyse the impact of individual mutations.
The aim of this study was to generate and characterize antibiotic-resistant M. genitalium mutants in vitro to understand the development of macrolide resistance in this bacterium.
Sequential MIC assays for azithromycin were performed using the laboratory strain of M. genitalium (G37) grown in Hayflick medium. Bacteria were enumerated by droplet digital PCR (ddPCR) targeting mgpB, and a new ddPCR assay was established to detect specific mutations in the 23S rRNA gene. MICs of selected macrolide antibiotics were determined in Hayflick medium. Whole genome sequencing (WGS) was performed on the Oxford Nanopore MinION.
After eight passages in azithromycin, a novel 23S rRNA gene mutation, G2057A (Escherichia coli numbering), was detected. The mutant did not display a detectable growth defect and had elevated MICs to azithromycin (8-fold), josamycin (8-fold) and erythromycin (16- to 32-fold). WGS did not identify other mutations likely to contribute to reduced macrolide susceptibility.
A novel 23S rRNA gene mutation was identified in M. genitalium. This variation is found in Mycoplasma hominis, which is intrinsically resistant to certain macrolides. While this mutation has not been observed clinically in M. genitalium, these findings have expanded our understanding of resistance mechanisms within the Mollicutes, in particular the propensity for M. genitalium to develop resistance, even in low concentrations of antibiotic, and the interaction of azithromycin with the ribosome.
由于抗菌药物耐药性问题，生殖支原体是一种越来越受关注的性传播细菌。耐药性通常由单核苷酸多态性介导；然而，生殖支原体的分离和培养困难限制了分析单个突变影响的能力。
本研究的目的是在体外产生并鉴定耐抗生素的生殖支原体突变体，以了解该细菌大环内酯类耐药性的发展。
使用在海弗利克培养基中生长的生殖支原体实验室菌株（G37）进行阿奇霉素的连续最低抑菌浓度（MIC）测定。通过靶向mgpB的液滴数字PCR（ddPCR）对细菌进行计数，并建立了一种新的ddPCR测定法来检测23S rRNA基因中的特定突变。在海弗利克培养基中测定所选大环内酯类抗生素的MIC。在牛津纳米孔MinION上进行全基因组测序（WGS）。
在阿奇霉素中传代八次后，检测到一个新的23S rRNA基因突变，G2057A（大肠杆菌编号）。该突变体未显示出可检测到的生长缺陷，对阿奇霉素（8倍）、交沙霉素（8倍）和红霉素（16至32倍）的MIC升高。WGS未发现其他可能导致大环内酯类敏感性降低的突变。
在生殖支原体中鉴定出一个新的23S rRNA基因突变。这种变异存在于人型支原体中，人型支原体对某些大环内酯类药物具有内在耐药性。虽然这种突变在生殖支原体的临床中尚未观察到，但这些发现扩展了我们对柔膜菌纲耐药机制的理解，特别是生殖支原体即使在低浓度抗生素下也有产生耐药性的倾向，以及阿奇霉素与核糖体的相互作用。
