Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from Hefei (2014-2015): genetic characteristics of antimicrobial resistance.

BACKGROUND: Antimicrobial resistance (AMR) and genetic determinants of resistance of N. gonorrhoeae isolates from Hefei, China, were characterized adding a breadth of information to the molecular epidemiology of gonococcal resistance in China. METHODS: 126 N. gonorrhoeae isolates from a hospital clinic in Hefei, were collected between January, 2014, and November, 2015. The minimum inhibitory concentration (MIC) of N. gonorrhoeae isolates for seven antimicrobials were determined by the agar dilution method. Isolates were tested for mutations in penA and mtrR genes and 23S rRNA, and also genotyped using N. gonorrhoeae multi-antigen sequence typing (NG-MAST). RESULTS: All N. gonorrhoeae isolates were resistant to ciprofloxacin; 81.7% (103/126) to tetracycline and 73.8% (93/126) to penicillin. 39.7% (50/126) of isolates were penicillinase producing N. gonorrhoeae (PPNG), 31.7% (40/126) were tetracycline resistant N. gonorrhoeae (TRNG) and 28.6% (36/126) were resistant to azithromycin. While not fully resistant to extended spectrum cephalosporins (ESCs), a total of 14 isolates (11.1%) displayed decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L, n = 10), cefixime (MIC ≥ 0. 25 mg/L, n = 1) or to both ESCs (n = 3). penA mosaic alleles XXXV were found in all isolates that harbored decreased susceptibility to cefixime, except for one. Four mutations were found in mtrR genes and mutations A2143G and C2599T were identified in 23S rRNA. No isolates were resistant to spectinomycin. Gonococcal isolates were distributed into diverse NG-MAST sequence types (STs); 86 separate STs were identified. CONCLUSIONS: N. gonorrhoeae isolates from Hefei during 2014-2015, displayed high levels of resistance to antimicrobials that had been recommended previously for treatment of gonorrhea, e.g., penicillin, tetracycline and ciprofloxacin. The prevalence of resistance to azithromycin was also high (28.6%). No isolates were found to be fully resistant to spectinomycin, ceftriaxone or cefixime; however, 11.1% isolates, overall, had decreased susceptibility to ESCs.

Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from symptomatic men attending the Nanjing sexually transmitted diseases clinic (2011-2012): genetic characteristics of isolates with reduced sensitivity to ceftriaxone.

BACKGROUND: Evolving gonococcal antimicrobial resistance (AMR) poses a serious threat to public health. The aim of this study was to: update antimicrobial susceptibility data of Neisseria gonorrhoeae recently isolated in Nanjing, China and identify specific deteminants of antimicrobial resistance and gentoypes of isolates with decreased sensitivity to ceftriaxone. METHODS: 334 N. gonorrhoeae isolates were collected consecutively from symptomatic men attending the Nanjing STD Clinic between April 2011 and December 2012. The minimum inhibitory concentrations (MICs) for penicillin, tetracycline, ciprofloxacin, spectinomycin and ceftriaxone were determined by agar plate dilution for each isolate. Penicillinase-producing N. gonorrhoeae (PPNG) and tetracycline-resistant N. gonorrhoeae (TRNG) were examined and typed for ß-lactamase and tetM encoding plasmids respectively. Isolates that displayed elevated MICs to ceftriaxone (MIC ≥0.125 mg/L) were also tested for mutations in penA, mtrR, porB1b, ponA and pilQ genes and characterized by Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST). RESULTS: 98.8% (330/334) of N. gonorrhoeae isolates were resistant to ciprofloxacin; 97.9% (327/334) to tetracycline and 67.7% (226/334) to penicillin. All isolates were susceptible to ceftriaxone (MIC ≤0.25 mg/L) and spectinomycin (MIC ≤32 mg/L). Plasmid mediated resistance was exhibited by 175/334 (52%) of isolates: 120/334 (36%) of isolates were PPNG and 104/334 (31%) were TRNG. 90.0% (108/120) of PPNG isolates carried the Asia type ß-lactamase encoding plasmid and 96% (100/104) of TRNG isolates carried the Dutch type tetM containing plasmid. Elevated MICs for ceftriaxone were present in 15 (4.5%) isolates; multiple mutations were found in penA, mtrR, porB1b and ponA genes. The 15 isolates were distributed into diverse NG-MAST sequence types; four different non-mosaic penA alleles were identified, including one new type. CONCLUSIONS: N. gonorrhoeae isolates in Nanjing generally retained similar antimicrobial resistance patterns to isolates obtained five years ago. Fluctuations in resistance plasmid profiles imply that genetic exchange among gonococcal strains is ongoing and is frequent. Ceftriaxone and spectinomycin remain treatments of choice of gonorrhea in Nanjing, however, decreased susceptibility to ceftriaxone and rising MICs for spectinomycin of N. gonorrhoeae isolates underscore the importance of maintaining surveillance for AMR (both phenotypic and genotypic).

A novel MVK missense mutation in one Chinese family with disseminated superficial actinic porokeratosis.

Disseminated superficial actinic porokeratosis (DSAP) is a severe chronic autosomal dominant cutaneous disorder with high genetic heterogeneity. mevalonate kinase, (MVK) a gene know to play an important role in regulation of calcium-induced keratinocyte differentiation and proliferation, has recently been suggested as the disease-causing gene for DSAP. Here we report a direct sequencing analysis of this gene in 3 DSAP families, 6 sporadic cases, and 100 unrelated healthy controls. We detected a heterozygous T to A transition at nucleotide 205 in exon 3 of MVK gene in one familial case. This mutation will result in an amino acid change at codon 69 (P.Ser69Thr), which is from a serine codon (TCA) to a threonine codon (ACA). No such mutation was detected in the unaffected family members or the 100 unrelated healthy controls. Our results demonstrated a novel missense mutation in MVK gene. This will be valuable for the diagnosis of DSAP as well as for genetic counseling and prenatal diagnosis of affected families.

[Refinement of DSAP1 locus and mutation detection for candidate genes].

Disseminated superficial actinic porokeratosis (DSAP) is an uncommon autosomal dominant chronic keratinization disorder,characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. In previous studies,the disease gene was mapped to 12q23. 2-24.1 (DSAP1), and 15q25. 1-26.1 (DSAP2). In this study,genome-wide scan was performed in two unrelated six-generation DSAP pedigrees to localize and identify the candidate gene(s) of disease. Linkage analysis showed that the cumulative maximum two-point lod score of 8.28 was obtained with the marker D12S84 at a recombination fraction theta of 0.00. Haplotype analysis defined an 8.0 cM critical region for DSAP gene(s) between markers D12S330 and D12S354 on 12q24. 1-q24. 2, which partially overlapped with the region identified for DSAP1. DNA sequencing of the coding exons of six candidate genes (CRY1, PWP1, ASCL4, PRDM4, KIAA0789 and CMKLR1) on the basis of their location in the critical overlap interval, failed to detect any mutation in DSAP patients. Thus, it is likely that these genes are not involved in DSAP.

Two closely linked variations in actin cytoskeleton pathway in a Chinese pedigree with disseminated superficial actinic porokeratosis.

BACKGROUND: Disseminated superficial actinic porokeratosis (DSAP) is an uncommon autosomal dominant chronic keratinization disorder, characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. Recently, SSH1 was identified as the DSAP candidate gene. OBJECTIVE: Our purpose was to determine the locus of DSAP and identify the candidate gene(s) of the disease. METHODS: Genome-wide scanning and linkage analysis were performed in a 6-generation Chinese family with DSAP. The coding exons and promoter region of the candidate genes were screened for the nucleotide variations. RESULTS: A missense mutation (p.Ser63Asn) in SSH1 and a variation (dbSNP3759383: G>A) in the promoter region of ARPC3 were closely linked with DSAP in the pedigree. CONCLUSION: Both SSH1 and ARPC3 are involved in the actin cytoskeleton pathway and interacted with adherent junctions in the epidermal cells. We suggested that cytoskeleton disorganization in epidermal cells was likely associated with the pathogenesis of DSAP.