Mosaic-Like Structure of Penicillin-Binding Protein 2 Gene (penA) in Clinical Isolates of Neisseria gonorrhoeae with Reduced Susceptibility to Cefixime

Research Laboratories, Toyama Chemical Co., Ltd., 2-4-1, Shimookui, Japan.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 01/2003; 46(12):3744-9. DOI: 10.1128/AAC.46.12.3744-3749.2002
Source: PubMed


Neisseria gonorrhoeae strains with reduced susceptibility to cefixime (MICs, 0.25 to 0.5 micro g/ml) were isolated from male urethritis patients in Tokyo, Japan, in 2000 and 2001. The resistance to cephems including cefixime and penicillin was transferred to a susceptible recipient, N. gonorrhoeae ATCC 19424, by transformation of the penicillin-binding protein 2 gene (penA) that had been amplified by PCR from a strain with reduced susceptibility to cefixime (MIC, 0.5 micro g/ml). The sequences of penA in the strains with reduced susceptibilities to cefixime were different from those of other susceptible isolates and did not correspond to the reported N. gonorrhoeae penA gene sequences. Some regions in the transpeptidase-encoding domain in this penA gene were similar to those in the penA genes of Neisseria perflava (N. sicca), Neisseria cinerea, Neisseria flavescens, and Neisseria meningitidis. These results showed that a mosaic-like structure in the penA gene conferred reductions in the levels of susceptibility of N. gonorrhoeae to cephems and penicillin in a manner similar to that found for N. meningitidis and Streptococcus pneumoniae.

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    • "Penicillin-binding proteins are involved in the synthesis of peptidoglycan, a major component of bacterial cell walls. Mosaic sequences of PBP2, resulting from recombination events involving penA gene sequences from other Neisseria species, have been identified in clinical isolates that demonstrate reduced susceptibility to cefixime and ceftriaxone [24-26]. Options to treat gonorrhoea if cephalosporins become ineffective are severely limited. "
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    ABSTRACT: A high level of resistance in Neisseria gonorrhoeae has developed against penicillins, sulphonamides, tetracyclines and quinolones, and recent surveillance data have shown a gradual reduction in sensitivity to current first-line agents with an upward drift in the minimum inhibitory concentration of ceftriaxone. Laboratory sensitivity testing suggests that gentamicin, an aminoglycoside, may be an effective treatment option for gonorrhoea infection when used as a single intramuscular dose. A search of electronic reference databases and grey literature was used to identify randomised trials and well-conducted prospective studies with concurrent controls evaluating single-dose gentamicin against placebo or a comparator regimen in the treatment of uncomplicated gonorrhoea infection in men and women aged 16 years and over. The primary outcome was microbiological cure of N. gonorrhoeae. Eight hundred and thirty-nine studies were identified, of which five (1,063 total participants) were included. All five studies administered single-dose gentamicin via intramuscular injection to men with uncomplicated gonococcal urethritis. Three studies were randomised trials, one was quasi-randomised and one was non-randomised but included a comparator arm. Comparator antibiotics included an alternative aminoglycoside or antibiotic used in the syndromic management of male urethritis. Methodology was poorly described in all five included studies. The high risk of bias within studies and clinical heterogeneity between studies meant that it was inappropriate to pool data for meta-analysis. Cure rates of 62% to 98% were reported with gentamicin treatment. The relative risk of cure was comparable between gentamicin and comparator antibiotics. The studies identified provide insufficient data to support or refute the efficacy and safety of single-dose intramuscular gentamicin in the treatment of uncomplicated gonorrhoea infection. Additional randomised trials to evaluate gentamicin for this indication are therefore required. Systematic review registration PROSPERO CRD42012002490
    Systematic Reviews 09/2014; 3(1):104. DOI:10.1186/2046-4053-3-104
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    • "The European gonorrhoea treatment guideline was also revised in 2012, now recommending treatment with ceftriaxone 500 mg plus azithromycin 2 g [23]. Mutations in the penA gene (mosaic gene or A501 mutations) encoding the penicillin-binding protein 2 (PBP2) is the main determinant for decreased susceptibility and resistance to ESCs [5,9,17,24-30]. For molecular epidemiological typing of gonococci, the N. gonorrhoeae multiantigen sequence typing (NG-MAST) has been used in many countries [31]. "
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    ABSTRACT: In Poland, gonorrhoea has been a mandatorily reported infection since 1948, however, the reported incidences are likely underestimated. No antimicrobial resistance (AMR) data for Neisseria gonorrhoeae has been internationally reported in nearly four decades, and data concerning genetic characteristics of N. gonorrhoeae are totally lacking. The aims of this study were to investigate the AMR to previously and currently recommended gonorrhoea treatment options, the main genetic resistance determinant (penA) for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolates in Poland in 2010-2012. N. gonorrhoeae isolates cultured in 2010 (n = 28), 2011 (n = 92) and 2012 (n = 108) in Warsaw and Bialystok, Poland, were examined using antimicrobial susceptibility testing (Etest), pyrosequencing of penA and N. gonorrhoeae multi-antigen sequence typing (NG-MAST). The proportions of N. gonorrhoeae isolates showing resistance were as follows: ciprofloxacin 61%, tetracycline 43%, penicillin G 22%, and azithromycin 8.8%. No isolates resistant to ceftriaxone, cefixime or spectinomycin were found. However, the proportion of isolates with an ESC MIC = 0.125 mg/L, i.e. at the resistance breakpoint, increased significantly from none in 2010 to 9.3% and 19% in 2012 for ceftriaxone and cefixime, respectively. Furthermore, 3.1% of the isolates showed multidrug resistance, i.e., resistance to ciprofloxacin, penicillin G, azithromycin, and decreased susceptibility to cefixime (MIC = 0.125 mg/L). Seventy-six isolates (33%) possessed a penA mosaic allele and 14 isolates (6.1%) contained an A501V/T alteration in penicillin-binding protein 2. NG-MAST ST1407 (n = 58, 25% of isolates) was the most prevalent ST, which significantly increased from 2010 (n = 0) to 2012 (n = 46; 43%). In Poland, the diversified gonococcal population displayed a high resistance to most antimicrobials internationally previously recommended for gonorrhoea treatment and decreasing susceptibility to the currently recommended ESCs. The decreasing susceptibility to ESCs was mostly due to the introduction of the internationally spread multidrug-resistant NG-MAST ST1407 in 2011. It is essential to promptly revise the gonorrhoea treatment guidelines, improve the gonorrhoea laboratory diagnostics, and implement quality assured surveillance of gonococcal AMR (ideally also treatment failures) in Poland.
    BMC Infectious Diseases 02/2014; 14(1):65. DOI:10.1186/1471-2334-14-65 · 2.61 Impact Factor
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    • "Mutations in the penA gene encoding the penicillin-binding protein 2 (PBP2) is the main determinant for decreased susceptibility and resistance to ESCs. Acquisition of a penA mosaic gene or an alteration of amino acid A501 in PBP2 result in a lower affinity for ESCs and consequently a decreased ESC susceptibility [6,9,16,26-32]. Mutations in the promoter or coding sequence of the repressor gene mtrR cause over-expression of the MtrCDE efflux pump system that export the ESCs out from the cell. This further decreases the susceptibility to ESCs [6,9,16,28,32-35]. "
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    ABSTRACT: Background Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major public health concern worldwide. In Vietnam, knowledge regarding N. gonorrhoeae prevalence and AMR is limited, and data concerning genetic characteristics of N. gonorrhoeae is totally lacking. Herein, we investigated the phenotypic AMR (previous, current and possible future treatment options), genetic resistance determinants for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolated in 2011 in Hanoi, Vietnam. Methods N. gonorrhoeae isolates from Hanoi, Vietnam isolated in 2011 (n = 108) were examined using antibiograms (Etest for 10 antimicrobials), Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), and sequencing of ESC resistance determinants (penA, mtrR and penB). Results The levels of in vitro resistance were as follows: ciprofloxacin 98%, tetracycline 82%, penicillin G 48%, azithromycin 11%, ceftriaxone 5%, cefixime 1%, and spectinomycin 0%. The MICs of gentamicin (0.023-6 mg/L), ertapenem (0.002-0.125 mg/L) and solithromycin (<0.016-0.25 mg/L) were relatively low. No penA mosaic alleles were found, however, 78% of the isolates contained an alteration of amino acid A501 (A501V (44%) and A501T (34%)) in the encoded penicillin-binding protein 2. A single nucleotide (A) deletion in the inverted repeat of the promoter region of the mtrR gene and amino acid alterations in MtrR was observed in 91% and 94% of the isolates, respectively. penB resistance determinants were detected in 87% of the isolates. Seventy-five different NG-MAST STs were identified, of which 59 STs have not been previously described. Conclusions In Vietnam, the highly diversified gonococcal population displayed high in vitro resistance to antimicrobials previously recommended for gonorrhoea treatment (with exception of spectinomycin), but resistance also to the currently recommended ESCs were found. Nevertheless, the MICs of three potential future treatment options were low. It is essential to strengthen the diagnostics, case reporting, and epidemiologic surveillance of gonorrhoea in Vietnam. Furthermore, the surveillance of gonococcal AMR and gonorrhoea treatment failures is imperative to reinforce. Research regarding novel antimicrobial treatment strategies (e.g., combination therapy) and new antimicrobials is crucial for future treatment of gonorrhoea.
    BMC Infectious Diseases 01/2013; 13(1):40. DOI:10.1186/1471-2334-13-40 · 2.61 Impact Factor
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