Increased antibiotic susceptibility inNeisseria gonorrhoeaethrough adaptation to the cervical environment

Abstract

28Neisseria gonorrhoeae is an urgent public health threat due to rapidly increasing incidence and 29 antibiotic resistance. In contrast with the trend of increasing resistance, clinical isolates that 30 have reverted to susceptibility regularly appear, prompting questions about which pressures 31 compete with antibiotics to shape gonococcal evolution. Here, we used genome-wide 32 association on the largest collection of N. gonorrhoeae isolates to date (n=4882) to identify loss-33 of-function (LOF) mutations in the efflux pump mtrCDE operon as a mechanism of increased 34 antibiotic susceptibility and demonstrate that these mutations are overrepresented in cervical 35 isolates relative to urethral isolates (odds ratio (OR) = 3.74, 95% CI [1.98-6.70]). In support of a 36 model in which pump expression incurs a fitness cost in this niche, cervical isolates were also 37 enriched relative to urethral isolates in LOF mutations in the mtrCDE activator mtrA (OR = 8.60,) and in farA, a subunit of the FarAB efflux pump (OR = 6.25, 95% CI [3.90-39 9.83]). In total, approximately 1 in 3 cervical isolates (36.4%) contained a LOF mutation in either 40 the efflux pump components mtrC or farA or the activator mtrA. Our findings extend beyond N. 41 gonorrhoeae to other Neisseria: mtrC LOF mutations are rare (<1%) in the primarily 42 nasopharyngeal-colonizing N. meningitidis in a collection of 14,798 genomes but enriched in a 43 heterosexual urethritis-associated lineage (8.6%, p = 9.90×10 -5 ), indicating that efflux pump 44 downregulation contributes broadly to the adaptation of pathogenic Neisseria to the female 45 urogenital tract. Overall, our findings highlight the impact of integrating microbial population 46 genomics with host metadata and demonstrate how host environmental pressures can lead to 47 increased antibiotic susceptibility. 48 49 50 51Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease gonorrhea. 52Antibiotics have played a key role in shaping gonococcal evolution 1-3 , with N. gonorrhoeae 53 gaining resistance to each of the first line antibiotics used to treat it 4-6 . As N. gonorrhoeae is an 54 obligate human pathogen, the mucosal niches it infects-most commonly including the urethra, 55 cervix, pharynx, and rectum-must also influence its evolution 7 . The gonococcal phylogeny 56 suggests the interaction of these factors, with an ancestral split between a relatively drug-57 susceptible lineage circulating primarily in heterosexuals and a relatively drug-resistant lineage 58 circulating primarily in men who have sex with men 3 . 59 60 Despite the deeply concerning increase in antibiotic resistance reported in gonococcal 61 populations globally 8 , some clinical isolates of N. gonorrhoeae have become more susceptible 62 to antibiotics 9,10 . This unexpected phenomenon prompts questions about which environmental 63 pressures could be drivers of increased susceptibility and the mechanisms by which 64 suppression or reversion of resistance may occur. To address these questions, we analy...

Improved Prediction of Bacterial Genotype-Phenotype Associations Using Interpretable Pangenome-Spanning Regressions

“…Using a simple estimate of shared sequence content as the kinship matrix led to a likely overestimate of heritability. For these antibiotics, we expect high h 2 , approaching 1, as we discover further causal mechanisms and include them in the model (55). These estimates are consistent with this expectation but are difficult to evaluate quantitatively.…”

Efflux Pump Antibiotic Binding Site Mutations Are Associated with Azithromycin Nonsusceptibility in Clinical Neisseria gonorrhoeae Isolates

“…Lyu and Moseng et al used cryo-electron microscopy to characterize key residues involved in drug binding by mosaic-like MtrD efflux pump alleles in Neisseria gonorrhoeae ( 1 ). Isogenic experiments introducing key MtrD substitutions R714G and K823E increased macrolide MICs, leading the authors to predict that nonmosaic MtrD “gonococcal strains bearing both the mtrR promoter and amino acid changes at MtrD positions 714 or 823 could lead to clinically significant levels of Azi nonsusceptibility resistance.” We tested this hypothesis by analyzing a global meta-analysis collection of 4,852 N. gonorrhoeae genomes ( 2 ). In support of their prediction, we identified clinical isolates with novel nonmosaic MtrD drug binding site substitutions across multiple genetic backgrounds associated with elevated azithromycin MICs ( Table 1 ).…”

Efflux pump antibiotic binding site mutations are associated with azithromycin nonsusceptibility in clinicalNeisseria gonorrhoeaeisolates

“…Isogenic experiments introducing key MtrD substitutions R714G and K823E increased macrolide MICs, leading the authors to predict that non-mosaic MtrD "gonococcal strains bearing both the mtrR promoter and amino acid changes at MtrD positions 714 or 823 could lead to clinically significant levels of Azi nonsusceptibility resistance". We tested this hypothesis by analyzing a global meta-analysis collection of 4852 N. gonorrhoeae genomes (2). In support of their prediction, we identified clinical isolates with novel non-mosaic MtrD drug binding site substitutions across multiple genetic backgrounds associated with elevated azithromycin MICs (Table).…”