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Shang W.,Chongqing Medical University | Hu Q.,Chongqing Medical University | Yuan W.,Chongqing Medical University | Yuan W.,Clinical Laboratory Diagnostic Center | And 11 more authors.
Microbial Drug Resistance | Year: 2016

Sequence type (ST) 239 with SCCmec type III methicillin-resistant Staphylococcus aureus (ST239-MRSA-III) is the most predominant multidrug-resistant clone in China. The subclone ST239-MRSA-III-t037 has been gradually replaced with ST239-MRSA-III-t030 since 2000. Subclones are characterized by drug resistance profiles. However, the mechanisms of the clonal dynamics and determinants of distinct drug resistance remain poorly understood. In the present study, 12 ST239-MRSA-III-t030 and 12 ST239-MRSA-III-t037 strains were collected from Chongqing, Guangzhou, and Shanghai; these strains were selected and investigated in terms of t030/t037 strain pairs. Independent growth curve assay revealed that the ST239-MRSA-III-t030 strains grew more rapidly, with significantly shorter doubling times, than the ST239-MRSA-III-t037 strains (p < 0.001). The ST239-MRSA-III-t037 strains exhibited slightly to moderately higher (3-13%) fitness cost than the ST239-MRSA-III-t030 strains in a competition assay in vitro. The ST239-MRSA-III-t037 strains yielded lower bacterial loads in the kidneys of the infected mice than the ST239-MRSA-III-t030 rivals in a coinfection assay (p < 0.05). The ST239-MRSA-III-t030 strains were resistant to rifampicin but susceptible to trimethoprim/sulfamethoxazole (SXT). In contrast, the ST239-MRSA-III-t037 strains were susceptible to rifampicin but resistant to SXT. The genetic determinants of the resistance to rifampicin and SXT in the MRSA strains were determined. Our results suggest that the relatively low fitness cost and characteristic drug resistance phenotype can help explain the current predominance of these ST239-MRSA-III-t030 strains in Chinese hospitals. © Copyright 2016, Mary Ann Liebert, Inc. 2016.

Wang Y.F.,Emory University | Fu J.,Clinical Laboratory Diagnostic Center
Journal of Thoracic Disease | Year: 2014

It is still challenging to prevent and treat respiratory infectious diseases. One critical step in the successful treatment of respiratory infections is rapid diagnosis by identifying the causative microorganisms in a timely fashion. However, traditional methods for identification of causative agents could not satisfy the need for rapid and accurate testing due to the limitations of technology-used. In recent years, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) has been validated and used for rapid identification of microorganism and for potential discovery of diseases associated biomarkers. We reviewed recent advances of MALDI-TOF-MS as the laboratory diagnostic tool for the rapid laboratory diagnosis of microorganisms associated with respiratory infectious diseases, with the focus on rapid identification of pathogenic bacteria and molecular markers discovery using MALDI-TOF-MS. With the advanced technologies such as MALDI-TOF, early and targeted therapies based on rapid identification of pathogens and could lead to quick and effective treatment of respiratory infections and better patient management. © Pioneer Bioscience Publishing Company.

Cheng H.,Chongqing Medical University | Yuan W.,Chongqing Medical University | Yuan W.,Clinical Laboratory Diagnostic Center | Hu Q.,Chongqing Medical University | And 12 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2013

Objectives: The distribution of methicillin-resistant Staphylococcus aureus (MRSA) clones is dynamic and geographically unique. To understand the changing epidemiology of MRSA infections in China, we performed a prospective, multicity surveillance study with molecular typing and phenotypic analysis to determine the association of major prevalent clones with their antimicrobial resistance profiles. Methods: A total of 517 S. aureus isolates collected between January 2009 and March 2012 fromsix cities in China were subjected to antibiogram analysis and molecular typing, including staphylococcal cassette chromosome mec typing, multilocus sequence typing, staphylococcal protein A gene typing and PFGE typing. Results: Among the isolates collected, 309 were characterized as MRSA, with a prevalence of 59.8%. Three major clones were found to be prevalent in China: ST239-MRSA-III-t030, ST239-MRSA-III-t037 and ST5-MRSA-II-t002. These three clones were associated with two characteristic resistance profiles, namely, gentamicin/ciprofloxacin/ rifampicin/levofloxacin for the first clone and gentamicin/ciprofloxacin/clindamycin/erythromycin/tetracycline/ levofloxacin/trimethoprim/sulfamethoxazole for the latter two. Several geographically unique minor clones were also identified. Conclusions: The predominant MRSA clones in China were associated with characteristic antimicrobial resistance profiles. Antibiotics for treating patients with MRSA infections can be selected based on the strain typing data. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

Hu Q.,Chongqing Medical University | Cheng H.,Chongqing Medical University | Yuan W.,Chongqing Medical University | Yuan W.,Clinical Laboratory Diagnostic Center | And 14 more authors.
Journal of Clinical Microbiology | Year: 2015

The emergence of Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) is a public health concern worldwide. PVL is associated with community-associated MRSA and is linked to skin and soft tissue infections (SSTIs). However, PVL genes have also been detected in health care-associated (HA) MRSA isolates. The diseases associated with PVL-positive HA-MRSA isolates and the distributions of PVL-encoding bacteriophages in HA-MRSA have not been determined. In this study, a total of 259 HA-MRSA strains isolated between 2009 and 2012 in China from inpatients with SSTIs, pneumonia, and bacteremia were selected for molecular typing, including staphylococcal cassette chromosome mec typing, multilocus sequence typing, and staphylococcal protein A gene typing. The PVL genes and PVL bacteriophages in the MRSA isolates were characterized by PCR. Among the tested MRSA isolates, 28.6% (74/259) were PVL positive. The high prevalence of PVL-carrying HA-MRSA was observed to be associated with SSTIs but not with pneumonia or bacteremia. The PVL-positive HA-MRSA isolates were colonized mainly by infective PVL phages, namely, Pdbl7247PVL, PdblSLT, and PdblSa2958. The distribution of PVL-carrying bacteriophages differed geographically. Our study highlights the potential risk of the emergence of multidrug-resistant HAMRSA strains with increased virulence. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Shi Q.,Clinical Laboratory Diagnostic Center | Cheng L.,Clinical Laboratory Diagnostic Center | Liu Z.,Clinical Laboratory Diagnostic Center | Hu K.,Clinical Laboratory Diagnostic Center | And 3 more authors.
Central European Journal of Immunology | Year: 2015

The p38 mitogen-activated protein kinase (MAPK) plays a key role in lipopolysaccharide (LPS)-induced signal transduction pathways that lead to inflammatory cytokine synthesis in macrophages; however, whether the inhibition of p38 MAPK regulates LPS-induced inflammatory cytokine expression in different types of macrophages remains the subject of debate. Herein, we assessed whether the inhibition of p38 MAPK by SB203580 regulates LPS-induced expression of the inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in RAW264.7 and resident peritoneal macrophages. Lipopolysaccharide stimulation of RAW264.7 macrophages or mouse resident peritoneal macrophages significantly increased TNF-α and IL-6 production. The addition of SB203580 to cultures dramatically blocked LPS-induced TNF-α production in RAW264.7 and mouse resident peritoneal macrophages, and dramatically blocked LPS-induced IL-6 production in RAW264.7 macrophages, but not in mouse resident peritoneal macrophages. Additionally, high concentrations of SB203580 resulted in increased IL-6 production. However, LPS-stimulation significantly up-regulated the mRNA transcript levels of TNF-α and IL-6 in RAW264.7 and mouse resident peritoneal macrophages, whereas pretreatment with SB203580 dramatically down-regulated LPS-induced mRNA transcript levels of TNF-α and IL-6 in these cells. Our data show that SB203580 differentially modulates LPS-induced production of the inflammatory cytokine IL-6 in two different sources of macrophages, and that this course of regulation occurs at the IL-6 mRNA post-transcriptional stage.

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