Anhui Center for Surveillance of Bacterial Resistance

Hefei, China

Anhui Center for Surveillance of Bacterial Resistance

Hefei, China
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Pan A.-J.,Anhui Medical University | Mei Q.,Anhui Medical University | Ye Y.,Anhui Medical University | Li H.-R.,Central South University | And 3 more authors.
Journal of Antibiotics | Year: 2017

The purpose of this study was to validate the mutant selection window (MSW) hypothesis in vitro and in vivo with Escherichia coli and Pseudomonas aeruginosa exposed to fosfomycin. Two standard strains of Gram-negative bacteria, those are E. coli ATCC 25922 and P. aeruginosa ATCC 27853, were exposed to fosfomycin at concentrations below MIC, between the MIC and the mutant prevention concentration (MPC), and above the MPC in Luria-Bertani broth and in a tissue-cage infection model, respectively. With the in vitro time-kill studies, there were bacterial re-growth and emergence of resistance thereafter for both strains at antibiotic concentrations of × 4, × 8 and × 16 MIC. In our animal model, the loss in susceptibility of P. aeruginosa at fosfomycin concentrations fluctuated between the lower and upper boundaries of the MSW. In contrast, the emergence of resistant mutants of E. coli was not observed in vivo, regardless of fosfomycin dosage. Interestingly, the in vitro-isolated resistant mutants of E. coli showed a decreased growth rate compared with the susceptible parental strains, whereas no fitness cost in P. aeruginosa was observed. The emergence of antibiotic resistance is shaped by several factors. MSW theory may not apply to all antimicrobial-pathogen combinations. Before it can be used as a framework for the design of antimicrobial therapy, the existence of the window must be demonstrated not only in vitro but also in vivo. © 2017 The Author(s).


Zhao L.,Anhui Medical University | Zhao L.,Anhui Center for Surveillance of Bacterial Resistance | Li H.,Central South University | Zhu Z.,University of Missouri | And 5 more authors.
Infection, Genetics and Evolution | Year: 2017

Acinetobacter baumannii has been becoming a great challenge to clinicians due to their resistance to almost all available antibiotics. In this study, we sequenced the genome from a multiple antibiotics resistant Acinetobacter baumannii stain which was named A. baumannii-1isolated from China by SMRT sequencing technology to explore its potential mechanisms to antibiotic resistance. We found that several mechanisms might contribute to the antibiotic resistance of Acinetobacter baumannii. Specifically, we found that SNP in genes associated with nucleotide excision repair and ABC transporter might contribute to its resistance to multiple antibiotics; we also found that specific genes associated with bacterial DNA integration and recombination, DNA-mediated transposition and response to antibiotics might contribute to its resistance to multiple antibiotics; Furthermore, specific genes associated with penicillin and cephalosporin biosynthetic pathway and specific genes associated with CHDL and MBL β-lactamase genes might contribute to its resistance to multiple antibiotics. Thus, the detailed mechanisms by which Acinetobacter baumannii show extensive resistance to multiple antibiotics are very complicated. Such a study might be helpful to develop new strategies to control Acinetobacter baumannii infection. © 2017 Elsevier B.V.


Xu X.-H.,Anhui Medical University | Ye Y.,Anhui Medical University | Hu L.-F.,Anhui Center for Surveillance of Bacterial Resistance | Hu L.-F.,Anhui Medical University | And 4 more authors.
BMC Infectious Diseases | Year: 2012

Background: Neisseria meningitidis serogroup C has emerged as a cause of epidemic disease in Hefei. The establishment of serogroup C as the predominant cause of endemic disease has not been described.Methods: We conducted national laboratory-based surveillance for invasive meningococcal disease during 2000-2010. Isolates were characterized by pulsed-field gel electrophoresis and multilocus sequence typing.Results: A total of 845 cases of invasive meningococcal disease were reported. The incidence increased from 1.25 cases per 100,000 population in 2000 to 3.14 cases per 100,000 in 2003 (p < 0.001), and peaked at 8.43 cases per 100,000 in 2005. The increase was mainly the result of an increase in the incidence of serogroup C disease. Serogroup C disease increased from 2/23 (9%) meningococcal cases and 0.11 cases per 100,000 in 2000 to 33/58 (57%) cases and 1.76 cases per 100,000 in 2003 (p < 0.01). Patients infected with serogroup C had serious complications more frequently than those infected with other serogroups. Specifically, 161/493 (32.7%) cases infected with serogroup C had at least one complication. The case-fatality rate of serogroup C meningitis was 11.4%, significantly higher than for serogroup A meningitis (5.3%, p = 0.021). Among patients with meningococcal disease, factors associated with death in univariate analysis were age of 15-24 years, infection with serogroup C, and meningococcemia.Conclusions: The incidence of meningococcal disease has substantially increased and serogroup C has become endemic in Hefei. The serogroup C strain has caused more severe disease than the previously predominant serogroup A strain. © 2012 Xu et al.; licensee BioMed Central Ltd.


Wei W.-J.,Anhui Medical University | Yang H.-F.,Anhui Medical University | Ye Y.,Anhui Medical University | Ye Y.,Anhui Center for Surveillance of Bacterial Resistance | And 2 more authors.
Chinese Medical Journal | Year: 2015

Objective: To review the origin, diagnosis, treatment and public health concern of New Delhi metallo-β-lactamase (NDM)-producing bacteria. Data Sources: We searched database for studies published in English. The database of PubMed from 2007 to 2015 was used to conduct a search using the keyword term "NDM and Acinetobacter or Enterobacteriaceae or Pseudomonas aeruginosa." Study Selection: We collected data including the relevant articles on international transmission, testing methods and treatment strategies of NDM-positive bacteria. Worldwide NDM cases were reviewed based on 22 case reports. Results: The first documented case of infection caused by bacteria producing NDM-1 occurred in India, in 2008. Since then, 13 blaNDM variants have been reported. The rise of NDM is not only due to its high rate of genetic transfer among unrelated bacterial species, but also to human factors such as travel, sanitation and food production and preparation. With limited treatment options, scientists try to improve available therapies and create new ones. Conclusions: In order to slow down the spread of these NDM-positive bacteria, a series of measures must be implemented. The creation and transmission of blaNDM are potentially global health issues, which are not issues for one country or one medical community, but for global priorities in general and for individual wound care practitioners specifically. © 2015, Chinese Medical Association. All rights reserved.


Zhang L.,Anhui Medical University | Zhou S.,Anhui Medical University | Pan A.,Anhui Medical University | Li J.,Anhui Medical University | And 2 more authors.
International Journal of Infectious Diseases | Year: 2015

The purpose of this study was to determine the species distribution and to monitor the antifungal susceptibility profiles of clinical Candida isolates collected in China from 2009 to 2013. Methods: The antifungal susceptibilities of 952 Candida isolates were tested. Results: Candida albicans was the most common species, accounting for 65.7% of the total isolates. The most frequently isolated non-albicans Candida species in this study was Candida glabrata (193, 20.3%). Nearly 7.6%, 3.2%, 1.8%, and 1.1% of the 952 isolates exhibited decreased susceptibility to fluconazole, voriconazole, itraconazole, and flucytosine, respectively. Moreover, seven C. albicans and one Candida krusei had an amphotericin B minimum inhibitory concentration (MIC) of 2. μg/ml. Conclusions: The distribution of species and the prevalence of antifungal resistance in Candida isolates varied among different areas in China. Continuous monitoring of resistance patterns is necessary to control the spread of resistance in clinical isolates of Candida species. © 2014 The Authors.


Zhu Y.-L.,Anhui Medical University | Yang H.-F.,Anhui Medical University | Liu Y.-Y.,Anhui Medical University | Hu L.-F.,Anhui Medical University | And 5 more authors.
Diagnostic Microbiology and Infectious Disease | Year: 2013

A total of 123 Shigella isolates were collected from SiXian area in Anhui, China. Screening was carried out by polymerase chain reaction (PCR) amplification of plasmid-mediated quinolone resistance (PMQR) determinants. Different β-blactamases genes, plasmid-borne blaAmpC, 16S rRNA methylase genes, integrons, and mutations in quinolone resistance-determining regions were analysed by PCR for the PMQR-positive isolates. © 2013 Elsevier Inc.


Yang H.-F.,Anhui Medical University | Cheng J.,Anhui Medical University | Hu L.-F.,Anhui Medical University | Ye Y.,Anhui Medical University | And 3 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2012

We investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants and examined the association of these determinants with extended-spectrum β-lactamases (ESBLs) and/or plasmid-mediated AmpC β-lactamases (pAmpCs) in Serratia marcescens isolates in China. In this study, the presence of PMQR determinants was significantly related to the coproduction of ESBLs and/or pAmpCs (CTX-M-14, SHV-5, DHA-1, and ACT-1), among which CTX-M-14 was the most common gene type. Copyright © 2012, American Society for Microbiology. All Rights Reserved.


Zhang L.,Anhui Medical University | Yang H.-F.,Anhui Medical University | Liu Y.-Y.,Anhui Center for Surveillance of Bacterial Resistance | Xu X.-H.,Anhui Medical University | And 5 more authors.
Diagnostic Microbiology and Infectious Disease | Year: 2013

We investigated the susceptibility of Candida albicans isolated from clinic specimens to azole antifungal agents and estimated the association of the ERG11 mutations with azole resistance during recent 5. years in China. In this study, novel mutations G346A, A434V, and L480F in ERG11 may be related to azole resistance in C. albicans. © 2013 Elsevier Inc.


Yang H.,Anhui Medical University | Chen G.,Anhui Medical University | Hu L.,Anhui Medical University | Liu Y.,Anhui Medical University | And 7 more authors.
International Journal of Antimicrobial Agents | Year: 2015

Antimicrobial treatment of multidrug-resistant Acinetobacter baumannii (MDR-AB) infections continues to pose significant challenges. With limited options, clinicians have been pushed towards using unorthodox combinations of licensed antibiotics. Although daptomycin/colistin combination appears to be a promising treatment option based on in vitro data, further preclinical work is needed. In this study, the A. baumannii-Galleria mellonella system was employed to study the in vivo efficacy of this combination in order to determine whether it should be explored further for the treatment of MDR-AB infections. The antimicrobial activity of colistin alone and in combination with daptomycin was assessed versus an A. baumannii type strain (ATCC 19606) and a MDR-AB clinical strain (GN2231) isolated in Anhui, China. Synergy studies were performed using the microtitre plate chequerboard assay and time-kill methodology. The in vivo activity of daptomycin/colistin combination was assessed using a G. mellonella larvae model. The combination of daptomycin and colistin was bactericidal against both strains tested. In chequerboard assays, daptomycin was highly active against A. baumannii when combined with colistin [fractional inhibitory concentration index (FICI) of <0.5]. Treatment of G. mellonella larvae infected with lethal doses of A. baumannii resulted in significantly enhanced survival rates when daptomycin was given with colistin compared with colistin treatment alone (P < 0.05). This work suggests that daptomycin/colistin combination is highly active against A. baumannii both in vitro and in a simple invertebrate model of infection. © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.


Zhu Y.-L.,Anhui Medical University | Hu L.-F.,Anhui Medical University | Mei Q.,Anhui Medical University | Cheng J.,Anhui Medical University | And 5 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2012

Objectives: To test the mutant selection window (MSW) hypothesis with Staphylococcus aureus exposed to vancomycin in an animal model and to compare in vivo and in vitro exposures that restrict the enrichment of resistant mutants. Methods: Local infection with S. aureus was established in rabbits, and the infected animals were treated with various doses of twice-daily vancomycin (half-life 6 h) for 3consecutive days to provide antibiotic concentrations below the MIC, between the MIC and the mutant prevention concentration (MPC), and above the MPC. Changes in susceptibility and the numbers of surviving organisms were monitored daily on agar plates containing 2× and 4× MIC of vancomycin. Results: S. aureus lost vancomycin susceptibility when drug concentrations at the site of infection fluctuated between the lower and upper boundaries of the MSW, defined in vitro as the MIC99 and the MPC, respectively. Both boundaries were determined in vitro, before starting animal studies. The value at which resistant mutants are not enriched in vivo was estimated as an AUC24/MPC value of ~15 h, where AUC24 is the area under the drug concentration time curve in a 24 h interval. The estimated anti-mutant AUC/MIC ratio in vivo was ≥200 h. Conclusions: These findings support the MSW hypothesis and the anti-mutant AUC/MIC ratio estimated in vivo is consistent with that reported in in vitro studies. Keeping vancomycin concentrations above the MPC or AUC24/MPC >15 h is a straightforward way to restrict the acquisition of resistance. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

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