In Vivo -Selected Compensatory Mutations Restore the Fitness Cost of Mosaic penA Alleles That Confer Ceftriaxone Resistance in Neisseria gonorrhoeae

作者：Leah R. Vincent, Samuel R. Kerr, Yang Tan, Joshua Tomberg, Erica L. Raterman, Julie C. Dunning Hotopp, Magnus Unemo, Robert A. Nicholas, Ann E. Jerse · 发表于：mBio · 年份：2018 · DOI：10.1128/mbio.01905-17 · 被引用次数：83 · 研究领域：Reproductive tract infections research、Bacterial Infections and Vaccines、Adolescent Sexual and Reproductive Health

ABSTRACT Resistance to ceftriaxone in Neisseria gonorrhoeae is mainly conferred by mosaic penA alleles that encode penicillin-binding protein 2 (PBP2) variants with markedly lower rates of acylation by ceftriaxone. To assess the impact of these mosaic penA alleles on gonococcal fitness, we introduced the mosaic penA alleles from two ceftriaxone-resistant (Cro r ) clinical isolates (H041 and F89) into a Cro s strain (FA19) by allelic exchange and showed that the resultant Cro r mutants were significantly outcompeted by the Cro s parent strain in vitro and in a murine infection model. Four Cro r compensatory mutants of FA19 penA41 were isolated independently from mice that outcompeted the parent strain both in vitro and in vivo . One of these compensatory mutants (LV41C) displayed a unique growth profile, with rapid log growth followed by a sharp plateau/gradual decline at stationary phase. Genome sequencing of LV41C revealed a mutation (G348D) in the acnB gene encoding the bifunctional aconitate hydratase 2/2 methylisocitrate dehydratase. Introduction of the acnB G348D allele into FA19 penA41 conferred both a growth profile that phenocopied that of LV41C and a fitness advantage, although not as strongly as that exhibited by the original compensatory mutant, suggesting the existence of additional compensatory mutations. The mutant aconitase appears to be a functional knockout with lower activity and expression than wild-type aconitase. Transcriptome sequencing (RNA-seq) analysi...