First description of a cefixime- and ciprofloxacin-resistant Neisseria gonorrhoeae isolate with mutations in key antimicrobial susceptibility–determining genes from the country of Georgia

Antimicrobial resistance in Neisseria gonorrhoeae is a global health problem. Enhanced international collaborative surveillance and disease control are needed to reduce the global burden of this important pathogen. Currently the antimicrobial resistance properties and molecular mechanisms of multidrug-resistant N. gonorrhoeae in the Republic of Georgia represent a significant knowledge gap. Here we report the isolation of a strain of N. gonorrhoeae exhibiting resistance to cefixime and ciprofloxacin with reduced susceptibility to penicillin and tetracycline from a patient being treated at a Georgian medical centre. Notably, this isolate was found to contain a mosaic penA allele and to harbour mutations in genes conferring susceptibility to the β-lactam, cephalosporin, fluoroquinolone, macrolide and penicillin classes of antibiotic. To our knowledge, this is the first report to describe the key mutations conferring the antimicrobial resistance properties of an isolate of N. gonorrhoeae from Georgia. Keywords: Antimicrobial, Georgia, gonorrhoea, mutation, Neisseria, resistanc

Tir phosphorylation and Nck/N-WASP recruitment by enteropathogenic and enterohaemorrhagic Escherichia coli during ex vivo colonization of human intestinal mucosa is different to cell culture models

Tir, the translocated intimin receptor of enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) and Citrobacter rodentium, is translocated into the host cell by a filamentous type III secretion system. Epithelial cell culture has demonstrated that Tir tyrosine phosphorylation is necessary for attaching effacing (A/E) lesion formation by EPEC and C. rodentium, but is not required by EHEC O157:H7. Recent in vivo work on C. rodentium has reported that Tir translocation, but not its phosphorylation, is necessary for colonization of the mouse colon. In this study we investigated the involvement of Tir and its tyrosine phosphorylation in EPEC and EHEC human intestinal colonization, N-WASP accumulation and F-actin recruitment using in vitro organ culture (IVOC). We showed that both EPEC and EHEC Tir are translocated into human intestinal epithelium during IVOC and that Tir is necessary for ex vivo intestinal colonization by both EPEC and EHEC. EPEC, but not EHEC, Tir is tyrosine phosphorylated but Tir phosphorylation-deficient mutants still colonize intestinal explants. While EPEC Tir recruits the host adaptor protein Nck to initiate N-WASP-Arp2/3-mediated actin polymerization, Tir derivatives deficient in tyrosine phosphorylation recruit N-WASP independently of Nck indicating the presence of a tyrosine phosphorylation-independent mechanism of A/E lesion formation and actin recruitment ex vivo by EPEC in man