Accuracy and reproducibility of the Etest to detect drug-resistant Neisseria gonorrhoeae to contemporary treatment

Papp, John R.; Rowlinson, Michael; O'Connor, Norman; Wholehan, Jason; Razeq, Jafar; Glennen, Anita; Ware, Dapne; Iwen, Peter C.; Lee, Lillian V.; Hagan, Celia

doi:10.1099/jmm.0.000651

Cited by 19 publications

(14 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Antimicrobial susceptibility testing was conducted using Etest strips on GCB-K plates, comparable MIC values to the agar dilution method, with the exception of cefixime for which Etests systemically report lower MICs[56]. In brief, cells from overnight plates were suspended in trypticase soy broth to a 0.5 McFarland standard and inoculated onto new GCB-K plates.…”

mentioning

confidence: 99%

Exploration of theNeisseriaresistome reveals resistance mechanisms in commensals that may be acquired byN. gonorrhoeaethrough horizontal gene transfer

Fiore

Raisman

Wong

et al. 2020

Preprint

View full text Add to dashboard Cite

Non-pathogenic Neisseria have repeatedly been demonstrated to transfer antibiotic resistance genes to their pathogenic relative, Neisseria gonorrhoeae. However, the resistance genotypes and subsequent phenotypes of non-pathogens within the genus have been studied and described less frequently. Here, we use Etests to characterize the minimum inhibitory concentrations (MICs) of a panel of Neisseria (n=26) - including several commensal species - acquired from the CDC & FDA's Antibiotic Resistance (AR) Isolate Bank to a suite of diverse antibiotics. We furthermore use whole genome sequencing and the Comprehensive Antibiotic Resistance Database (CARD) Resistance Gene Identifier (RGI) platform to predict possible causal resistance-encoding mutations. Within this panel, resistant isolates to all tested antimicrobials including penicillin (n=5/26), ceftriaxone (n=2/26), cefixime (n=3/26), tetracycline (n=10/26), azithromycin (n=11/26), and ciprofloxacin (n=4/26) were found. In total we identify 63 distinct mutations predicted by RGI to be involved in resistance. The presence of several of these mutations had clear associations with increases in MIC such as: DNA gyrase subunit A (gyrA) (S91F) and ciprofloxacin, tetracycline resistance protein (tetM) and 30S ribosomal protein S10 (rpsJ) (V57M) and tetracycline, and TEM-type beta-lactamases and penicillin. However, mutations with strong associations to macrolide and cephalosporin resistance were not conclusive. This work serves as an initial exploration into the resistance-encoding mutations harbored by non-pathogenic Neisseria, which will ultimately aid in prospective surveillance for novel resistance mechanisms that may be rapidly acquired by N. gonorrhoeae.

show abstract

mentioning

confidence: 99%

Exploration of theNeisseriaresistome reveals resistance mechanisms in commensals that may be acquired byN. gonorrhoeaethrough horizontal gene transfer

Fiore

Raisman

Wong

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Papp et al . have previously shown that MICs using gradient diffusion for CFX were consistently underreported by one or two dilutions [ 8 ]. Liu et al .…”

Section: Discussionmentioning

confidence: 99%

Gradient diffusion susceptibility testing for Neisseria gonorrhoeae: an accurate alternative to agar dilution in high-MIC strains?

Desjardins

Lefebvre

Lavallée

et al. 2020

Access Microbiology

View full text Add to dashboard Cite

Introduction The correlation of antimicrobial susceptibility testing (AST) between agar dilution and gradient diffusion for Neisseria gonorrhoeae is not well established, especially in strains with high MICs. Aim The objective of this study was to evaluate the accuracy of gradient diffusion for N. gonorrhoeae . Methods Fifty strains of N. gonorrhoeae , all tested by the agar dilution method according to CLSI methods and confirmed to be genetically distinct using molecular typing (NG-MAST), were selected. Isolates with high MICs were targeted. Gradient diffusion was performed for ceftriaxone (CRO), cefixime (CFX), azithromycin (AZT), tetracycline (TET) and fosfomycin (FOS) using two different commercial antimicrobial strips on different culture media (a non-commercial GC agar base with 1 % defined growth supplement and two commercial media). The performance of agar gradient diffusion was assessed based on accuracy, using essential and category agreements (EA and CA). Results Essential and categorical agreement were over 90 % for CRO, CFX and AZT on the two commercial agar media tested. Category disagreements were seen for CFX and AZT, mostly just very major errors. For TET, EA ranged from 80 to 96 % and CA ranged from 38 to 76 %, most of the misclassifications being minor errors. Finally, EA for FOS ranged between 80 and 98 %. Conclusion Gradient diffusion is an accurate and acceptable alternative for CRO, CFX and AZT. Caution is advised when MICs are reported by gradient diffusion approach breakpoints because of the possibility of very major errors. The use of gradient diffusion is limited for TET because of the high rate of minor errors.

show abstract

“…Isolates for both azithromycin and ciprofloxacin test panels were selected to be representative of the known diversity within the gonococcal population. Antimicrobial susceptibility testing was conducted using Etest strips (40) or the agar dilution method (32), and MICs were recorded after 24 h of growth. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) defines azithromycin reduced susceptibility as MICs of Ն1 g/ml (41), while GISP uses a breakpoint of Ն2 g/ml (32).…”

Section: Methodsmentioning

confidence: 99%

Impact of Species Diversity on the Design of RNA-Based Diagnostics for Antibiotic Resistance in Neisseria gonorrhoeae

Wadsworth

Sater

Bhattacharyya

et al. 2019

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Quantitative assessment of antibiotic-responsive RNA transcripts holds promise for a rapid point-of-care (POC) diagnostic tool for antimicrobial susceptibility testing. These assays aim to distinguish susceptible and resistant isolates by transcriptional differences upon drug exposure. However, an often-overlooked dimension of designing these tests is that the genetic diversity within a species may yield differential transcriptional regulation independent of resistance phenotype. Here, we use a phylogenetically diverse panel of Neisseria gonorrhoeae and transcriptome profiling coupled with reverse transcription-quantitative PCR to test this hypothesis, to identify azithromycin responsive transcripts and evaluate their potential diagnostic value, and to evaluate previously reported diagnostic markers for ciprofloxacin resistance (porB and rpmB). Transcriptome profiling confirmed evidence of genetic distance and population structure impacting transcriptional response to azithromycin. Taking this into account, we found azithromycin-responsive transcripts overrepresented in susceptible strains compared to resistant strains and selected four candidate diagnostic transcripts (rpsO, rplN, omp3, and NGO1079) that were the most significantly differentially regulated between phenotypes across drug exposure. RNA signatures for these markers categorically predicted resistance in 19/20 cases, with the one incorrect categorical assignment for an isolate at the threshold of reduced susceptibility. Finally, we found that porB and rpmB expression were not uniformly diagnostic of ciprofloxacin resistance in a panel of isolates with unbiased phylogenetic sampling. Overall, our results suggest that RNA signatures as a diagnostic tool are promising for future POC diagnostics; however, development and testing should consider representative genetic diversity of the target pathogen.

show abstract

Accuracy and reproducibility of the Etest to detect drug-resistant Neisseria gonorrhoeae to contemporary treatment

Abstract: Overall, the Etest method yielded reproducible MIC values within each laboratory with the azithromycin and ceftriaxone MIC results consistent to the reference agar dilution method while the cefixime result tended to provide a lower MIC value.

Cited by 19 publications

References 17 publications

Exploration of theNeisseriaresistome reveals resistance mechanisms in commensals that may be acquired byN. gonorrhoeaethrough horizontal gene transfer

Exploration of theNeisseriaresistome reveals resistance mechanisms in commensals that may be acquired byN. gonorrhoeaethrough horizontal gene transfer

Gradient diffusion susceptibility testing for Neisseria gonorrhoeae: an accurate alternative to agar dilution in high-MIC strains?

Impact of Species Diversity on the Design of RNA-Based Diagnostics for Antibiotic Resistance in Neisseria gonorrhoeae

Contact Info

Product

Resources

About