Molecular Analysis of Antimicrobial Resistance Mechanisms in Neisseria gonorrhoeae Isolates from Ontario, Canada

Abstract

Surveillance of gonococcal antimicrobial resistance and the molecular characterization of the mechanisms underlying these resistance phenotypes are essential in order to establish correct empirical therapies, as well as to describe the emergence of new mechanisms in local bacterial populations. To address these goals, 149 isolates were collected over a 1-month period (October-November 2008) at the Ontario Public Health Laboratory, Toronto, Canada, and susceptibility profiles (8 antibiotics) were examined. Mutations in previously identified targets or the presence of some enzymes related to resistance (r), nonsusceptibility (ns) (resistant plus intermediate categories), or reduced susceptibility (rs) to the antibiotics tested were also studied. A significant proportion of nonsusceptibility to penicillin (PEN) (89.2%), tetracycline (TET) (72.3%), ciprofloxacin (CIP) (29%), and macrolides (erythromycin [ERY] and azithromycin; 22.3%) was found in these strains. Multidrug resistance was observed in 18.8% of the collection. Although all the strains were susceptible to spectinomycin and extended-spectrum cephalosporins (ESC) (ceftriaxone and cefixime), 9.4% of them displayed reduced susceptibility to extended-spectrum cephalosporins. PBP 2 mosaic structures were found in all of these ESC rs isolates. Alterations in the mtrR promoter, MtrR repressor (TET r , PEN ns , ESC rs , and ERY ns ), porin PIB (TET r and PEN ns ), and ribosomal protein S10 (TET r ) and double mutations in gyrA and parC quinolone resistance-determining regions (QRDRs) (CIP r ) were associated with and presumably responsible for the resistance phenotypes observed. This is the first description of ESC rs in Canada. The detection of this phenotype indicates a change in the epidemiology of this resistance and highlights the importance of continued surveillance to preserve the last antimicrobial options available.

Azithromycin Resistance Is Coevolving with Reduced Susceptibility to Cephalosporins in Neisseria gonorrhoeae in Ontario, Canada

“…Case reports of AZM-resistant N. gonorrhoeae have been described in many countries, including Canada and the United States (10)(11)(12)(13)(14)(15)(16)(17)(18), but only rarely has AZM-resistant N. gonorrhoeae been reported to be associated with concurrent reduced susceptibility to 3GC (16,17). In Canada, AZM-resistant N. gonorrhoeae was first identified in 1997, and the first AZM-resistant isolates were identified in Ontario in 1998 (10).…”

“…In addition, 34 isolates (22.8%) displayed only reduced susceptibility to erythromycin (MICs, Ն2 g/ml) and AZM (MICs, 0.25 to 0.5 g/ml). Some of these isolates were associated with the N. gonorrhoeae multiantigen sequence typing (NG-MAST) sequence type 3158 (ST3158) and ST1407 (18). ST3158 and ST1407 are closely related (they share the same tbpB allele 110 and have just 2 point mutations of difference between their por alleles) and were previously linked to reduced susceptibility (18)(19)(20)(21) or resistance to 3GC (2,3).…”

“…Some of these isolates were associated with the N. gonorrhoeae multiantigen sequence typing (NG-MAST) sequence type 3158 (ST3158) and ST1407 (18). ST3158 and ST1407 are closely related (they share the same tbpB allele 110 and have just 2 point mutations of difference between their por alleles) and were previously linked to reduced susceptibility (18)(19)(20)(21) or resistance to 3GC (2,3). In this study, we examined the prevalence of AZM-resistant N. gonorrhoeae from July 2010 to February 2013, assessed the rate of concurrent cephalosporin resistance under current treatment recommendations, and analyzed the clonal distribution of AZM-resistant isolates in Ontario, Canada.…”

“…All isolates in that initial study had AZM MICs of 2 to 4 g/ml, and to date, no high-level AZM-resistant isolates of N. gonorrhoeae have been reported in the country. More recently, we conducted a surveillance of antimicrobial resistance in gonococci from Ontario and showed a high prevalence of isolates displaying nonsusceptibility (resistant plus intermediate categories) to penicillin (89.2%), tetracycline (72.3%), and ciprofloxacin (29%) and reduced susceptibility to 3GC (18). In addition, 34 isolates (22.8%) displayed only reduced susceptibility to erythromycin (MICs, Ն2 g/ml) and AZM (MICs, 0.25 to 0.5 g/ml).…”

Genotyping of the Resistance Determinant of Neisseria Gonorrhoeae with Reduced Susceptibility to Ceftriaxone in Manaus-AMBrazil

“…In this report, we describe the molecular characteristics of the N. gonorrhoeae strain NgFUAM84, isolated from the wianfe@yahoo.com.br urethral discharge of a male patient, with MIC of 0.064μg/mL for ceftriaxone in E-test (AB Biodisk, Solna, Sweden) [9]. The determinants of resistance to ESCs: penA, ponA, porB, mtrR and pilQ were amplified by PCR (Proflex PCR System-Applied Biosystems) using primers previously described [10,11]. The sequencing of amplicons was performed on the ABI 3130 Genetic Analyzer (Applied Biosystems).…”