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- Bala, Manju, et al.
(författare)
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Gentamicin in vitro activity and tentative gentamicin interpretation criteria for the CLSI and calibrated dichotomous sensitivity disc diffusion methods for Neisseria gonorrhoeae
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - Oxford, United Kingdom : Oxford University Press. - 0305-7453 .- 1460-2091. ; 71:7, s. 1856-1859
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: XDR Neisseria gonorrhoeae imposes the threat of untreatable gonorrhoea. Gentamicin is considered for future treatment; however, no interpretation criteria for the CLSI and calibrated dichotomous sensitivity (CDS) disc diffusion (DD) techniques are available for N. gonorrhoeae. We investigated the in vitro gentamicin activity by MIC and DD methods, proposed DD breakpoints and determined DD ranges for 10 international quality control (QC) strains.Methods: Gentamicin susceptibility of 333 N. gonorrhoeae isolates, including 323 clinical isolates and 10 QC strains, was determined. MIC determination (Etest) and DD methods (CLSI and CDS) were performed. The relationship between MIC, inhibition zone diameter and annular radius was determined by linear regression analysis and the correlation coefficient (r) was calculated.Results: Gentamicin MICs for the QC strains were within published ranges. Of the 323 clinical isolates, according to published breakpoints 75.9%, 23.5% and 0.6% were susceptible, intermediately susceptible and resistant, respectively. Based on error minimization with MICs of ≤4, 8-16 and ≥32 mg/L, breakpoints proposed are susceptible ≥16 mm, intermediately susceptible 13-15 mm and resistant ≤12 mm for the CLSI method and susceptible ≥6 mm, less susceptible 3-5 mm and resistant ≤2 mm for the CDS technique.Conclusions: Low resistance to gentamicin was identified and gentamicin might be a future treatment option for gonorrhoea. Tentative gentamicin zone breakpoints were defined for two DD methods and QC ranges for 10 international reference strains were established. Our findings suggest that in resource-poor settings where MIC testing is not a feasible option, the DD methods can be used to indicate gentamicin resistance.
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- Muhammad, Ibrahim, et al.
(författare)
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Characterisation of blaTEM genes and types of β-lactamase plasmids in Neisseria gonorrhoeae - the prevalent and conserved blaTEM-135 has not recently evolved and existed in the Toronto plasmid from the origin
- 2014
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Ingår i: BMC Infectious Diseases. - : BioMed Central. - 1471-2334. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern worldwide. It has been recently feared that the blaTEM-1 gene is, via blaTEM-135, evolving into an extended-spectrum β-lactamase (ESBL), which could degrade all cephalosporins including ceftriaxone. The aims of the present study were to characterize the blaTEM genes, types of β-lactamase plasmids, the degradation of ampicillin by TEM-135 compared to TEM-1, and to perform molecular epidemiological typing of β-lactamase-producing N. gonorrhoeae strains internationally.METHODS: β-lactamase producing N. gonorrhoeae isolates (n = 139) cultured from 2000 to 2011 in 15 countries were examined using antibiograms, blaTEM gene sequencing, β-lactamase plasmid typing, and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Furthermore, the blaTEM gene was sequenced in the first described Toronto plasmid (pJD7), one of the first Asian plasmids (pJD4) and African plasmids (pJD5) isolated in Canada. The degradation of ampicillin by TEM-135 compared to TEM-1 was examined using a MALDI-TOF MS hydrolysis assay.RESULTS: Six different blaTEM sequences were identified (among isolates with 125 different NG-MAST STs), i.e. blaTEM-1 (in 104 isolates), blaTEM-135 (in 30 isolates), and four novel blaTEM sequences (in 5 isolates). The blaTEM-1 allele was only found in the African and Asian plasmids, while all Rio/Toronto plasmids possessed the blaTEM-135 allele. Most interesting, the first described gonococcal Toronto plasmid (pJD7), identified in 1984, also possessed the highly conserved blaTEM-135 allele. The degradation of ampicillin by TEM-135 compared to TEM-1 was indistinguishable in the MALDI-TOF MS hydrolysis assay.CONCLUSIONS: blaTEM-135, encoding TEM-135, is predominantly and originally associated with the Rio/Toronto plasmid and prevalent among the β-lactamase producing gonococcal strains circulating globally. blaTEM-135 does not appear, as previously hypothesized, to have recently evolved due to some evolutionary selective pressure, for example, by the extensive use of extended-spectrum cephalosporins worldwide. On the contrary, the present study shows that blaTEM-135 existed in the Toronto plasmid from its discovery and that blaTEM-135 is highly conserved (not further evolved in the past >30 years). Nevertheless, international studies for monitoring the presence of different blaTEM alleles, the possible evolution of the blaTEM-135 allele, and the types of β-lactamase producing plasmids, remain imperative.
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- Sethi, Sunil, et al.
(författare)
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Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from India, Pakistan and Bhutan in 2007-2011
- 2013
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Ingår i: BMC Infectious Diseases. - : BioMed Central. - 1471-2334. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: Knowledge on antimicrobial drug resistance and genetic characteristics of Neisseria gonorrhoeae isolates circulating in India, Pakistan, and Bhutan is sorely lacking. In this paper, we describe the prevalence of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates from India, Pakistan, and Bhutan in 2007-2011. Methods: Antimicrobial susceptibility and beta-lactamase production were tested for 65 N. gonorrhoeae isolates from India (n=40), Pakistan (n=18) and Bhutan (n=7) using Etest methodology (eight antimicrobials) and nitrocefin solution, respectively. Resistance determinants, i.e. penA, mtrR, porB1b, gyrA, and parC, were sequenced. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed for molecular epidemiology. Results: The highest resistance level was observed for ciprofloxacin (94%), followed by penicillin G (68%), erythromycin (62%), tetracycline (55%), and azithromycin (7.7%). All the isolates were susceptible to ceftriaxone, cefixime, and spectinomycin. Thirty-four (52%) of the isolates were producing beta-lactamase. No penA mosaic alleles or A501-altered alleles of penicillin-binding protein 2 were identified. Forty-nine NG-MAST STs were identified, of which 42 STs have not been previously described worldwide. Conclusions: Based on this study, ceftriaxone, cefixime, and spectinomycin can be used as an empirical first-line therapy for gonorrhoea in India, Pakistan, and Bhutan, whereas ciprofloxacin, penicillin G, tetracycline, erythromycin, and azithromycin should not be. It is imperative to strengthen the laboratory infrastructure in this region, as well as to expand the phenotypic and genetic surveillance of antimicrobial resistance, emergence of new resistance, particularly, to extended-spectrum cephalosporins, and molecular epidemiology.
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