Quality Assurance for Antimicrobial Susceptibility Testing of Neisseria gonorrhoeae in Canada, 2003 to 2012

Synthesis of imidazole-fused nitrogen-bridgehead heterocycles catalysed by lipase and their antifungal and antimicrobial bioactivity

An effective approach for selective C-N bond formation for synthesising imidazo[1,2-a] pyridine-based heterocycles using porcine pancreatic lipase (PPL) as a biocatalyst has been devised. Under moderate conditions, a series of imidazo[1,2-a]pyridine-based heterocycle derivatives were synthesised with remarkable selectivity in good-to-excellent yields (89-95%). Further, the antimicrobial and antifungal activities of derivatives 3ha, 3ka, 3fa, 3hc, and 3eb were observed, and they were found to be biologically active in antimicrobial susceptibility tests for Gram-positive bacteria (Enterococcus faecalis ATCC 29212 and Staphylococcus auris ATCC 25923), Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and fungal strains (Candida albicans ATCC 90028 and Candida tropicalis ATCC 750).

Use of genome sequencing to resolve differences in gradient diffusion and agar dilution antimicrobial susceptibility testing performance of Neisseria gonorrhoeae isolates in Alberta, Canada

Agar dilution is the gold standard method for phenotypic antimicrobial susceptibility testing (AST) for Neisseria gonorrhoeae. However, this method is laborious and requires expertise, so laboratories that perform N. gonorrhoeae AST may choose alternative methods such as disk diffusion and gradient diffusion. In this study, we retrospectively compare the performance of gradient diffusion to agar dilution for 2,394 unique N. gonorrhoeae isolates identified in Alberta from 2017 to 2020 against azithromycin, cefixime, ceftriaxone, ciprofloxacin, penicillin, and tetracycline. Genome sequencing was utilized to resolve discrepancies between AST methods, detect antimicrobial resistance markers, and identify trends between error rates and sequence types (STs) of isolates. Over 90% of N. gonorrhoeae isolates were susceptible to azithromycin, cefixime, and ceftriaxone, whereas decreased susceptibility was observed for ciprofloxacin, penicillin, and tetracycline. Categorical (CA) and essential agreement (EA) was poorest between the two methods for penicillin (CA: 86.02%; EA: 77.69%) and tetracycline (CA: 47.22%; EA: 55.96%); however, the low CA was primarily attributed to minor errors. Antimicrobial agents with errors outside of acceptable limits included azithromycin (very major error: 18.42%; major error: 7.73%) and tetracycline (very major error: 6.17%). Genome sequencing on a subset of isolates resolved 30.3% of the azithromycin major errors and confirmed the azithromycin or tetracycline very major errors. Significant associations between certain STs and error types for azithromycin and tetracycline were also identified. Overall, gradient diffusion compared well to agar dilution for cefixime, ceftriaxone, and ciprofloxacin, and genome sequencing was identified as a useful tool to arbitrate discrepant susceptibility testing results between gradient diffusion and agar dilution for N. gonorrhoeae.

Cytotoxicity Test of Active Compounds Natural Ingredients of Snail Mucus (Achatina fulica) Against BHK-21 Fibroblast Cells

Snails are unpleasant yet beneficial. Rural people have used one to treat illnesses like toothache for years. We will test snail's mucus Achatina fulica's cytotoxic activity against Baby Hamster Kidney (BHK-21) fibroblast cells at 12.5%, 25%, 50%, 100% and its resistance to Phorpyromonas gingivalis, Fusobacterium nucleatum, E. Faecalis, and S. aureus using Microtetrazolium (MTT) assay. The test and comparison solution was incubated with 5x103/100 l cells in 96-well plates. 5 mg/mL MTT completed the solution's incubation. ELISA readers measured purple color intensity. The formula transformed absorbance data at 595 nm into percent alive cells. ELISA readers read data. ANOVA, parametric Kolmogorov-Smirnov data normality test were performed. The cytotoxicity statistical test shows the following results: 12.5 % (0.76875 ±0.01117), 25% (0.49350 ±0.004796), 50% (0.30250 ±0.006658) and 100% (0.171 ±0.10488). The lowest cytotoxicity of Achatina fulica snail mucus is 12.5% with an average of 0.768. Achatina fulica snail mucus resists Phorpyromonas gingivalis, Fusobacterium nucleatum, E. Faecalis, and S. aureus at 12.5%.

Promising antibacterial activities of anethole and green-synthesized magnetite nanoparticles against multiple antibiotic-resistant bacteria

The emergence of antibiotic resistance is considered a major threat, and this problem is exacerbated due to the excessive use of antibiotics. Therefore, it is necessary to find new antimicrobials that are effective against pathogenic bacteria resistant to existing antimicrobials. This study presents a novel antimicrobial approach for the bio-control of multi-antibiotic-resistant (MAR) bacteria. Ten antibiotic discs were used to evaluate the bacterial sensitivity. Five bacterial strains showed resistance to all the tested antibiotic groups. The following MAR bacterial strains were selected, and their identification was confirmed by 16S rRNA with an accession number on the NCBI: Shigella flexneri MZ350855.1; Klebsiella aerogenes MZ352107.1; Serratia marcescens MZ618709.1; Yersinia enterocolitica MZ673567.1; and Achromobacter denitrificans OK560350.1. Star anise extract (SAE) gives the highest inhibitory efficiency against isolated MAR bacteria between three local plant extracts. SAE was used to synthesize magnetite nanoparticles (MNPs) using a simple and eco-friendly green biosynthesis technique. Synthesized MNPs were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, Fourier transform infrared, and transmission electron microscopy techniques. The effect of synthesized magnetic nanoparticles for wastewater treatment in bacterial portion demonstrated remarkable bactericidal performance against total bacterial count with a percentage reduction of 84% using 0.05 g, and the efficiency of decreasing heavy metals was estimated.

Linear regression equations to predict β-lactam, macrolide, lincosamide and fluoroquinolone minimum inhibitory concentrations from molecular antimicrobial resistance determinants in Streptococcus pneumoniae

Antimicrobial resistance in Streptococcus pneumoniae represents a threat to public health and monitoring the dissemination of resistant strains is essential to guiding health policy. Multiple-variable linear regression modeling was used to determine the contributions of molecular antimicrobial resistance determinants to antimicrobial minimum inhibitory concentration (MIC) for penicillin, ceftriaxone, erythromycin, clarithromycin, clindamycin, levofloxacin, and trimethoprim/sulfamethoxazole. Training data sets consisting of Canadian S. pneumoniae isolated from 1995 to 2019 were used to generate multiple-variable linear regression equations for each antimicrobial. The regression equations were then applied to validation data sets of Canadian (n=439) and USA (n=607 and n=747) isolates. The MIC for β-lactam antimicrobials were fully explained by amino acid substitutions in motif regions of the penicillin binding proteins PBP1a, PPB2b, and PBP2x. Accuracy of predicted MICs within one doubling dilution to phenotypically determined MICs for penicillin was 97.4%, ceftriaxone 98.2%; erythromycin 94.8%; clarithromycin 96.6%; clindamycin 98.2%; levofloxacin 100%; and trimethoprim/sulfamethoxazole 98.8%; with an overall sensitivity of 95.8% and specificity of 98.0%. Accuracy of predicted MICs to the phenotypically determined MICs was similar to phenotype-only MIC comparison studies. The ability to acquire detailed antimicrobial resistance information directly from molecular determinants will facilitate the transition from routine phenotypic testing to whole genome sequencing analysis and can fill the surveillance gap in an era of increased reliance on nucleic acid assay diagnostics to better monitor the dynamics of S. pneumoniae.

Antibacterial activities of hexadecanoic acid methyl ester and green-synthesized silver nanoparticles against multidrug-resistant bacteria

Antibacterial drug resistance is considered one of the biggest threats to human health worldwide, and the overuse of antibiotics accelerates this problem. Multidrug-resistant (MDR) bacteria are becoming harder to treat as the antibiotics used to treat them become less effective. Therefore, it is necessary to evaluate novel methods to control MDR bacteria. In this study, 40 bacterial isolates were collected from diabetic patients. The sensitivity of 40 bacterial isolates to seven antibiotics was evaluated. Four bacterial isolates were resistant to all antibiotic groups. The MDR pathogenic bacteria were selected and identified morphologically and biochemically and confirmed by VITEK® 2 system as follows: Staphylococcus aureus W35, Pseudomonas aeruginosa D31, Klebsiella pneumoniae DF30, and K. pneumoniae B40. Identification of the most resistant P. aeruginosa D31 was confirmed by the sequencing of a 16S ribosomal RNA gene with an accession number (MW241596). The inhibitory activity of eight types of native grown plant extracts against MDR bacteria was studied. Clove alcoholic extract (CAE) showed the highest inhibitory activity against MDR bacteria. Gas chromatography-mass spectrometry analysis of partially purified CAE at 0.9 Rf detected by thin-layer chromatography showed an active compound named hexadecenoic acid methyl ester with the highest antimicrobial effect against clinical pathogenic bacteria. The formation of silver nanoparticles (AgNPs) by CAE was studied. Evaluation of AgNPs was investigated by X-ray diffraction, UV-Vis, and transmission electron microscopy. The antibacterial effect of AgNPs after 2, 4, and 6 days in light and dark conditions was evaluated. Finally, the AgNPs synthesized using CAE possess good inhibition activity against the tested pathogenic bacteria. As a result, the bactericidal components listed above were promising in reducing MDR bacteria and can be used for treatments of bacterial infection and in the development of safe products with a natural base.

External quality assessment (EQA) of Neisseria gonorrhoeae antimicrobial susceptibility testing in primary laboratories in Germany

BACKGROUND

Worldwide, an increase in antimicrobial resistance (AMR) of Neisseria gonorrhoeae has been observed. Until now, no protocol for an external quality assessment (EQA) has been available for Germany. The German gonococcal resistance network (GORENET) performed an EQA of primary laboratories in Germany in order to assess quality of antibiotic susceptibility testing, to gain information about laboratory procedures and to assess the impact of these procedures on test results.

METHODS

Laboratories assessed drug susceptibility to cefixime, ceftriaxone, azithromycin, penicillin and ciprofloxacin for five N. gonorrhoeae strains, using their standard laboratory protocols. Minimal inhibitory concentrations (MICs) were compared to World Health Organisation (WHO) consensus results (or, if not available, reference laboratory results), while deviation by +/- one doubling dilution was accepted. Data on laboratory procedures were collected via a standardised questionnaire. Generalized linear models and conditional inference trees (CTREE) were used to assess relationships between laboratory procedures and testing outcomes.

RESULTS

Twenty-one primary laboratories participated in the EQA in June 2018. 96% of ciprofloxacin MICs were reported within accepted deviations, as well as 88% for cefixime, 85% for ceftriaxone, 79% for penicillin and 70% for azithromycin. The use of interpretation standards and general laboratory procedures like agar base, incubation settings or the use of control strains strongly differed between laboratories. In statistical analysis, incubation time of cultures < 24 h was associated with correct measurements. Additionally, a 5% CO2 concentration was associated with correct results regarding azithromycin compared to 3%. CTREE analysis showed that incubation time, humidity and CO2 concentration had the greatest influence on the average deviation from consensus results.

CONCLUSIONS

In conclusion, we report the development of a protocol for N. gonorrhoeae antimicrobial susceptibility testing in Germany. While testing results were in accordance with the expected consensus results in 70-96%, depending on the antibiotic agent, laboratory methodology was heterogeneous and may significantly affect the testing quality. We therefore recommend the development of a standard operating procedure (SOP) for N. gonorrhoeae susceptibility testing in Germany.

Equations To Predict Antimicrobial MICs in Neisseria gonorrhoeae Using Molecular Antimicrobial Resistance Determinants

The emergence of Neisseria gonorrhoeae strains that are resistant to azithromycin and extended-spectrum cephalosporins represents a public health threat, that of untreatable gonorrhea infections. Multivariate regression modeling was used to determine the contributions of molecular antimicrobial resistance determinants to the overall antimicrobial MICs for ceftriaxone, cefixime, azithromycin, tetracycline, ciprofloxacin, and penicillin. A training data set consisting of 1,280 N. gonorrhoeae strains was used to generate regression equations which were then applied to validation data sets of Canadian (n = 1,095) and international (n = 431) strains. The predicted MICs for extended-spectrum cephalosporins (ceftriaxone and cefixime) were fully explained by 5 amino acid substitutions in PenA, A311V, A501P/T/V, N513Y, A517G, and G543S; the presence of a disrupted mtrR promoter; and the PorB G120 and PonA L421P mutations. The correlation of predicted MICs within one doubling dilution to phenotypically determined MICs of the Canadian validation data set was 95.0% for ceftriaxone, 95.6% for cefixime, 91.4% for azithromycin, 98.2% for tetracycline, 90.4% for ciprofloxacin, and 92.3% for penicillin, with an overall sensitivity of 99.9% and specificity of 97.1%. The correlations of predicted MIC values to the phenotypically determined MICs were similar to those from phenotype MIC-only comparison studies. The ability to acquire detailed antimicrobial resistance information directly from molecular data will facilitate the transition to whole-genome sequencing analysis from phenotypic testing and can fill the surveillance gap in an era of increased reliance on nucleic acid assay testing (NAAT) diagnostics to better monitor the dynamics of N. gonorrhoeae.

World Health Organization Global Gonococcal Antimicrobial Surveillance Program (WHO GASP): review of new data and evidence to inform international collaborative actions and research efforts

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a serious public health problem, compromising the management and control of gonorrhoea globally. Resistance in N. gonorrhoeae to ceftriaxone, the last option for first-line empirical monotherapy of gonorrhoea, has been reported from many countries globally, and sporadic failures to cure especially pharyngeal gonorrhoea with ceftriaxone monotherapy and dual antimicrobial therapies (ceftriaxone plus azithromycin or doxycycline) have been confirmed in several countries. In 2018, the first gonococcal isolates with ceftriaxone resistance plus high-level azithromycin resistance were identified in England and Australia. The World Health Organization (WHO) Global Gonococcal Antimicrobial Surveillance Program (GASP) is essential to monitor AMR trends, identify emerging AMR and provide evidence for refinements of treatment guidelines and public health policy globally. Herein we describe the WHO GASP data from 67 countries in 2015-16, confirmed gonorrhoea treatment failures with ceftriaxone with or without azithromycin or doxycycline, and international collaborative actions and research efforts essential for the effective management and control of gonorrhoea. In most countries, resistance to ciprofloxacin is exceedingly high, azithromycin resistance is present and decreased susceptibility or resistance to ceftriaxone has emerged. Enhanced global collaborative actions are crucial for the control of gonorrhoea, including improved prevention, early diagnosis, treatment of index patient and partner (including test-of-cure), improved and expanded AMR surveillance (including surveillance of antimicrobial use and treatment failures), increased knowledge of correct antimicrobial use and the pharmacokinetics and pharmacodynamics of antimicrobials and effective drug regulations and prescription policies (including antimicrobial stewardship). Ultimately, rapid, accurate and affordable point-of-care diagnostic tests (ideally also predicting AMR and/or susceptibility), new therapeutic antimicrobials and, the only sustainable solution, gonococcal vaccine(s) are imperative.

Ten years of external quality assessment (EQA) of Neisseria gonorrhoeae antimicrobial susceptibility testing in Europe elucidate high reliability of data

Background

Confidence in any diagnostic and antimicrobial susceptibility testing data is provided by appropriate and regular quality assurance (QA) procedures. In Europe, the European Gonococcal Antimicrobial Susceptibility Programme (Euro-GASP) has been monitoring the antimicrobial susceptibility in Neisseria gonorrhoeae since 2004. Euro-GASP includes an external quality assessment (EQA) scheme as an essential component for a quality-assured laboratory-based surveillance programme. Participation in the EQA scheme enables any problems with the performed antimicrobial susceptibility testing to be identified and addressed, feeds into the curricula of laboratory training organised by the Euro-GASP network, and assesses the capacity of individual laboratories to detect emerging new, rare and increasing antimicrobial resistance phenotypes. Participant performance in the Euro-GASP EQA scheme over a 10 year period (2007 to 2016, no EQA in 2013) was evaluated.

Methods

Antimicrobial susceptibility category and MIC results from the first 5 years (2007–2011) of the Euro-GASP EQA were compared with the latter 5 years (2012–2016). These time periods were selected to assess the impact of the 2012 European Union case definitions for the reporting of antimicrobial susceptibility.

Results

Antimicrobial susceptibility category agreement in each year was ≥91%. Discrepancies in susceptibility categories were generally because the MICs for EQA panel isolates were on or very close to the susceptibility or resistance breakpoints. A high proportion of isolates tested over the 10 years were within one (≥90%) or two (≥97%) MIC log₂ dilutions of the modal MIC, respectively. The most common method used was Etest on GC agar base. There was a shift to using breakpoints published by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) in the latter 5 years, however overall impact on the validity of results was limited, as the percentage categorical agreement and MIC concordance changed very little between the two five-year periods.

Conclusions

The high level of comparability of results in this EQA scheme indicates that high quality data are produced by the Euro-GASP participants and gives confidence in susceptibility and resistance data generated by laboratories performing decentralised testing.

High levels of susceptibility to new and older antibiotics in Neisseria gonorrhoeae isolates from Saskatchewan (2003-15): time to consider point-of-care or molecular testing for precision treatment?

Objectives

The antimicrobial susceptibility of Neisseria gonorrhoeae isolates from Saskatchewan was determined retrospectively (2003-15) to ascertain temporal trends to both current and older antimicrobials used for treatment.

Method

The agar dilution method was used to test the antimicrobial susceptibilities of 685 isolates to seven antibiotics.

Results

Over the period, only three (0.4%) gonococcal isolates had reduced susceptibility to cefixime and/or ceftriaxone. All isolates were susceptible to spectinomycin. Over 95% of the isolates tested were susceptible to azithromycin except in 2010 and 2013 (27.6% and 7.2% resistant, respectively). One isolate was resistant to both azithromycin and cefixime. Ciprofloxacin resistance was seen in < 5% of isolates prior to 2010, but in > 5% thereafter. From 2006 to 2012, and in 2015, penicillin resistance was detected in < 5% (0%-4.0%) of isolates, but in > 5% for the rest of the study period. Tetracycline resistance remained >5% (11.8%-89.1%) throughout the study. Plasmid-mediated resistance to tetracycline fluctuated between 0% and 17.5% of isolates tested. Four isolates were MDR and two isolates were XDR.

Conclusions

N. gonorrhoeae isolates were largely susceptible (∼85%) to antibiotics no longer recommended for treatment, such as penicillin and ciprofloxacin. Gonorrhoea in Saskatchewan is primarily (>95%) diagnosed by nucleic acid amplification testing, which does not permit antimicrobial susceptibility testing. The development of molecular testing, or point-of-care tests, to evaluate antimicrobial susceptibility, would enhance knowledge of true levels of resistance and allow discretion as to whether older but still effective antibiotics could be used in individual patient care.

Quality assurance for antimicrobial susceptibility testing of Neisseria gonorrhoeae in Latin American and Caribbean countries, 2013-2015

OBJECTIVES

A Neisseria gonorrhoeae antimicrobial susceptibility quality control comparison programme was re-established in Latin America and the Caribbean to ensure antimicrobial susceptibility data produced from the region are comparable nationally and internationally.

METHODS

Three panels, consisting of N. gonorrhoeae isolates comprising reference strains and other characterised isolates were sent to 11 participating laboratories between 2013 and 2015. Antimicrobial susceptibilities for these isolates were determined using agar dilution, Etest or disc diffusion methods. Modal minimum inhibitory concentrations (MICs) for each panel isolate/antibiotic combination were calculated. The guidelines of the Clinical and Laboratory Standards Institute were used for interpretations of antimicrobial susceptibility. The agreement of MICs with the modal MICs was determined for each of the participating laboratories as well as for each of the antibiotics tested.

RESULTS

Five of 11 laboratories that participated in at least one panel had an overall average agreement between participants' MIC results and modal MICs of >90%. For other laboratories, agreements ranged from 60.0% to 82.4%. The proportion of agreement between interpretations for all the antibiotics, except penicillin and tetracycline, was >90%. The percentages of agreement between MIC results and their modes for erythromycin, spectinomycin, cefixime and azithromycin were >90%. Tetracycline, ceftriaxone and ciprofloxacin agreement ranged from 84.5% to 89.1%, while penicillin had 78.8% agreement between MICs and modal MICs.

CONCLUSIONS

The participating laboratories had acceptable results, similar to other international quality assurance programmes. It is important to ensure continuation of the International Gonococcal Antimicrobial Susceptibility Quality Control Comparison Programme to ensure that participants can identify and correct any problems in antimicrobial susceptibility testing for N. gonorrhoeae as they arise and continue to generate reproducible and reliable data.