Background A number of randomized controlled trials have found that doxycycline post exposure prophylaxis (PEP) can reduce the incidence of gonorrhoea, chlamydia and syphilis in men who have sex with men (MSM). If tetracycline resistance is associated with resistance to other antimicrobials in a range of bacterial species, then doxycycline PEP could have the unintended effect of selecting for resistance to other antimicrobials in these bacterial species. Methods Antimicrobial susceptibility data were retrieved from two sources: pubMLST ( https://pubmlst.org/ ) and Pathogenwatch ( https://pathogen.watch/ ) for the following bacterial pathogens: Klebsiella pneumoniae, Salmonella enterica subsp. Enterica serovar Typhi , Campylobacter jejuni, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes. We assessed if tetracycline resistance was associated with resistance to six relevant antimicrobials. Results We found evidence of cross resistance to various antimicrobials in all six bacterial species assessed. Cross resistance was found in 4 of 5 antimicrobials for K. pneumoniae, 1 of 2 for C. jejuni, 3 of 5 for S. enterica subsp. Enterica serovar Typhi, 5 of 5 for S. aureus, 5 of 6 for S. pneumoniae and 2 of 3 for S. pyogenes. These associations include a higher prevalence of methicillin resistance in tetracycline resistant S. aureus, penicillin resistance in S. pneumoniae, macrolide and clindamycin resistance in S. pyogenes, fluoroquinolone resistance in S. enterica subsp. Enterica serovar Typhi and third-generation cephalosporin resistance in K. pneumoniae. Conclusion These results suggest that studies evaluating the effects of doxycycline PEP should include the effects of doxycycline on resistance not only to doxycycline but also to other antimicrobials and in a broader array of bacterial species than has been included in doxycycline PEP studies thus far.

Antibiotic tolerance is associated with antibiotic treatment failure, and molecular mechanisms underlying tolerance are poorly understood. We recently succeeded in inducing tolerance to ceftriaxone (CRO) in an N. gonorrhoeae reference isolate. In a prior in vitro study, six biological replicates of WHO P strains were exposed to CRO (10× the MIC) followed by overnight growth, and tolerance was assessed using a modified Tolerance Disc (T.D.) test. In the current study, we characterized the mutation profile of these CRO-tolerant phenotypes. The whole genome was sequenced from isolates from different replicates and time points. We identified mutations in four genes that may contribute to ceftriaxone tolerance in N. gonorrhoeae, including a mutation in the enolase (eno) gene that arose independently in three lineages.

The PorB porins are the major pore-forming proteins in the genus Neisseria . The trimeric PorB porins consist of 16 highly conserved transmembrane domains that form an amphipathic β-sheet connected by short periplasmic turns and eight extracellular hydrophilic loops. These loops are immunogenic and also play an important role in mediating antimicrobial influx. This study sought to (i) characterize the variations in Neisserial loop 3(355–438 bp) associated with intermediate resistance to penicillin/tetracycline and (ii) evaluate if there was evidence of horizontal gene transfer in any of the loops. We collated an integrated database consisting of 19 018 Neisseria spp. genomes – 17 882 Neisseria gonorrhoeae , 114 Neisseria meningitidis and 1022 commensal Neisseria spp. To identify the porB alleles, a gene-by-gene approach (chewBBACA) was employed. To evaluate the presence of recombination events, the Recombination Detection Programme (RDP4) was used. In total, 3885 porB alleles were detected. Paralogues were identified in 17 Neisseria isolates. Putative recombination was identified in loop regions. Intraspecies recombination among N. gonorrhoeae isolates and interspecies recombination between N. meningitidis and commensal Neisseria spp., and N. gonorrhoeae and N. lactamica were identified. Here, we present a large-scale study of 19 018 Neisseria isolates to describe recombination and variation in the porB gene. Importantly, we found putative recombination in loop regions between the pathogenic and non-pathogenic Neisseria spp. These findings suggest the need for pheno- and genotypic surveillance of antimicrobial susceptibility in commensal Neisseria spp. to prevent the emergence of AMR in the pathogenic Neisseria . This article contains data hosted by Microreact.