scholarly journals Tandem Amplification of the Staphylococcal Cassette Chromosome mec Element Can Drive High-Level Methicillin Resistance in Methicillin-Resistant Staphylococcus aureus

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Laura A. Gallagher ◽  
Simone Coughlan ◽  
Nikki S. Black ◽  
Pierce Lalor ◽  
Elaine M. Waters ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Tandem Repeats ◽  
Chemostat Culture ◽  
Sequence Data ◽  
Methicillin Resistance ◽  
Mutational Event ◽  
Methicillin Resistant ◽  
Content Type ◽  
High Level ◽  
Staphylococcal Cassette Chromosome

ABSTRACT Hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) strains typically express high-level, homogeneous (HoR) β-lactam resistance, whereas community-associated MRSA (CA-MRSA) more commonly express low-level heterogeneous (HeR) resistance. Expression of the HoR phenotype typically requires both increased expression of the mecA gene, carried on the staphylococcal cassette chromosome mec element (SCCmec), and additional mutational event(s) elsewhere on the chromosome. Here the oxacillin concentration in a chemostat culture of the CA-MRSA strain USA300 was increased from 8 μg/ml to 130 μg/ml over 13 days to isolate highly oxacillin-resistant derivatives. A stable, small-colony variant, designated HoR34, which had become established in the chemostat culture was found to have acquired mutations in gdpP, clpX, guaA, and camS. Closer inspection of the genome sequence data further revealed that reads covering SCCmec were ∼10 times overrepresented compared to other parts of the chromosome. Quantitative PCR (qPCR) confirmed >10-fold-higher levels of mecA DNA on the HoR34 chromosome, and MinION genome sequencing verified the presence of 10 tandem repeats of the SCCmec element. qPCR further demonstrated that subculture of HoR34 in various concentrations of oxacillin (0 to 100 μg/ml) was accompanied by accordion-like contraction and amplification of the SCCmec element. Although slower growing than strain USA300, HoR34 outcompeted the parent strain in the presence of subinhibitory oxacillin. These data identify tandem amplification of the SCCmec element as a new mechanism of high-level methicillin resistance in MRSA, which may provide a competitive advantage for MRSA under antibiotic selection.

scholarly journals Prevalence of Chlorhexidine-Resistant Methicillin-Resistant Staphylococcus aureus following Prolonged Exposure

2014 ◽  
Vol 58 (8) ◽  
pp. 4404-4410 ◽  
Author(s):  
Carey D. Schlett ◽  
Eugene V. Millar ◽  
Katrina B. Crawford ◽  
Tianyuan Cui ◽  
Jeffrey B. Lanier ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Molecular Analysis ◽  
Prolonged Exposure ◽  
Controlled Trial ◽  
Epidemiological Data ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mupirocin Resistance ◽  
High Level ◽  
Study Participants

ABSTRACTChlorhexidine has been increasingly utilized in outpatient settings to control methicillin-resistantStaphylococcus aureus(MRSA) outbreaks and as a component of programs for MRSA decolonization and prevention of skin and soft-tissue infections (SSTIs). The objective of this study was to determine the prevalence of chlorhexidine resistance in clinical and colonizing MRSA isolates obtained in the context of a community-based cluster-randomized controlled trial for SSTI prevention, during which 10,030 soldiers were issued chlorhexidine for body washing. We obtained epidemiological data on study participants and performed molecular analysis of MRSA isolates, including PCR assays for determinants of chlorhexidine resistance and high-level mupirocin resistance and pulsed-field gel electrophoresis (PFGE). During the study period, May 2010 to January 2012, we identified 720 MRSA isolates, of which 615 (85.4%) were available for molecular analysis, i.e., 341 clinical and 274 colonizing isolates. Overall, only 10 (1.6%) of 615 isolates were chlorhexidine resistant, including three from the chlorhexidine group and seven from nonchlorhexidine groups (P> 0.99). Five (1.5%) of the 341 clinical isolates and five (1.8%) of the 274 colonizing isolates harbored chlorhexidine resistance genes, and four (40%) of the 10 possessed genetic determinants for mupirocin resistance. All chlorhexidine-resistant isolates were USA300. The overall prevalence of chlorhexidine resistance in MRSA isolates obtained from our study participants was low. We found no association between extended chlorhexidine use and the prevalence of chlorhexidine-resistant MRSA isolates; however, continued surveillance is warranted, as this agent continues to be utilized for infection control and prevention efforts.

scholarly journals Complete Genome Sequence of Systemically Disseminated Sequence Type 8 Staphylococcal Cassette Chromosome mec Type IVl Community-Acquired Methicillin-Resistant Staphylococcus aureus

2017 ◽  
Vol 5 (35) ◽  
Author(s):  
Junzo Hisatsune ◽  
Hideharu Hagiya ◽  
Sumiko Shiota ◽  
Motoyuki Sugai
Keyword(s):  
Staphylococcus Aureus ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Sequence Type ◽  
Methicillin Resistant ◽  
Content Type ◽  
Staphylococcal Cassette Chromosome ◽  
Epidermal Cell Differentiation

ABSTRACT Staphylococcus aureus JH4899, a community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate collected from a patient with systematically disseminated infection, is classified as sequence type 8 and carries the staphylococcal cassette chromosome mec type IVl (SCCmecIVl). It produces TSST-1, SEC, a newly discovered enterotoxin (SE1), and epidermal cell differentiation inhibitor A (EDIN-A). Here, we present the complete genome sequence of the chromosome and a plasmid harboring the se1 and ednA genes.

scholarly journals Novel Type XII Staphylococcal Cassette ChromosomemecHarboring a New Cassette Chromosome Recombinase, CcrC2

2015 ◽  
Vol 59 (12) ◽  
pp. 7597-7601 ◽  
Author(s):  
Zhaowei Wu ◽  
Fan Li ◽  
Dongliang Liu ◽  
Huping Xue ◽  
Xin Zhao
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
The United States ◽  
Gene Complex ◽  
Coagulase Negative Staphylococci ◽  
Typing Method ◽  
Content Type ◽  
Staphylococcal Cassette Chromosome ◽  
Sequence Identities

ABSTRACTExcision and integration of staphylococcal cassette chromosomemec(SCCmec) are mediated by cassette chromosome recombinases (Ccr), which play a crucial role in the worldwide spread of methicillin resistance in staphylococci. We report a novelccrgene,ccrC2, in the SCCmecof aStaphylococcus aureusisolate, BA01611, which showed 62.6% to 69.4% sequence identities to all publishedccrC1sequences. A further survey found that theccrC2gene was mainly located among coagulase-negative staphylococci (CoNS) and could be found in staphylococcal isolates from China, the United States, France, and Germany. Theccrgene complex harboring theccrC2gene was designated a type 9 complex, and the SCCmecof BA01611 was considered a novel type and was designated type XII (9C2). This novel SCCmecelement in BA01611 was flanked by a pseudo-SCC element (ΨSCCBA01611) carrying a truncatedccrA1gene. Both individual SCC elements and a composite SCC were excised from the chromosome based on detection of extrachromosomal circular intermediates. We advocate inclusion of the ccrC2gene and type 9ccrgene complex during revision of the SCCmectyping method.

scholarly journals Novel Types of Staphylococcal Cassette ChromosomemecElements Identified in Clonal Complex 398 Methicillin-Resistant Staphylococcus aureus Strains

2011 ◽  
Vol 55 (6) ◽  
pp. 3046-3050 ◽  
Author(s):  
Shanshuang Li ◽  
Robert Leo Skov ◽  
Xiao Han ◽  
Anders Rhod Larsen ◽  
Jesper Larsen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Clonal Complex ◽  
Subtype C ◽  
Methicillin Resistant ◽  
Content Type ◽  
Original Host ◽  
Mrsa Strains ◽  
Type V ◽  
Staphylococcal Cassette Chromosome

ABSTRACTThe structures of staphylococcal cassette chromosomemec(SCCmec) elements carried by 31 clonal complex 398 (CC398) methicillin-resistantStaphylococcus aureus(MRSA) strains isolated from the participants at a conference were analyzed. The SCCmecs were classified into novel types, namely, IX, X, V(5C2&5) subtype c, and IVa. Type V(5C2&5) subtype c, IX, and X SCCmecs carried genes conferring resistance to metals. The structures of SCCmecs from CC398 strains were distinct from those normally found in humans, adding to the evidence that humans are not the original host for CC398.

scholarly journals Chlorhexidine and Mupirocin Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolates in the REDUCE-MRSA Trial

2016 ◽  
Vol 54 (11) ◽  
pp. 2735-2742 ◽  
Author(s):  
Mary K. Hayden ◽  
Karen Lolans ◽  
Katherine Haffenreffer ◽  
Taliser R. Avery ◽  
Ken Kleinman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Cluster Randomized Trial ◽  
Confidence Limits ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Infection ◽  
Mupirocin Resistance ◽  
Cluster Randomized ◽  
High Level

Whether targeted or universal decolonization strategies for the control of methicillin-resistant Staphylococcus aureus (MRSA) select for resistance to decolonizing agents is unresolved. The REDUCE-MRSA trial (ClinicalTrials registration no. NCT00980980) provided an opportunity to investigate this question. REDUCE-MRSA was a 3-arm, cluster-randomized trial of either screening and isolation without decolonization, targeted decolonization with chlorhexidine and mupirocin, or universal decolonization without screening to prevent MRSA infection in intensive-care unit (ICU) patients. Isolates from the baseline and intervention periods were collected and tested for susceptibility to chlorhexidine gluconate (CHG) by microtiter dilution; mupirocin susceptibility was tested by Etest. The presence of the qacA or qacB gene was determined by PCR and DNA sequence analysis. A total of 3,173 isolates were analyzed; 2 were nonsusceptible to CHG (MICs, 8 μg/ml), and 5/814 (0.6%) carried qacA or qacB . At baseline, 7.1% of MRSA isolates expressed low-level mupirocin resistance, and 7.5% expressed high-level mupirocin resistance. In a mixed-effects generalized logistic regression model, the odds of mupirocin resistance among clinical MRSA isolates or MRSA isolates acquired in an ICU in intervention versus baseline periods did not differ across arms, although estimates were imprecise due to small numbers. Reduced susceptibility to chlorhexidine and carriage of qacA or qacB were rare among MRSA isolates in the REDUCE-MRSA trial. The odds of mupirocin resistance were no different in the intervention versus baseline periods across arms, but the confidence limits were broad, and the results should be interpreted with caution.

scholarly journals Role of the Accessory Gene Regulatoragrin Community-Associated Methicillin-Resistant Staphylococcus aureus Pathogenesis

2011 ◽  
Vol 79 (5) ◽  
pp. 1927-1935 ◽  
Author(s):  
Gordon Y. C. Cheung ◽  
Rong Wang ◽  
Burhan A. Khan ◽  
Daniel E. Sturdevant ◽  
Michael Otto
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Regulatory System ◽  
Accessory Gene ◽  
Methicillin Resistant ◽  
Content Type ◽  
Fibrinogen Binding ◽  
Gene Regulatory System ◽  
Differential Gene ◽  
Mrsa Strains

ABSTRACTThe molecular basis underlying the pathogenic success of community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) is not completely understood, but differential gene expression has been suggested to account at least in part for the high virulence of CA-MRSA strains. Here, we show that theagrgene regulatory system has a crucial role in the development of skin infections in the most prevalent CA-MRSA strain USA300. Importantly, our data indicate that this is due to discrepancies between theagrregulon of CA-MRSA and those of hospital-associated MRSA and laboratory strains. In particular,agrregulation in strain USA300 led to exceptionally strong expression of toxins and exoenzymes, upregulation of fibrinogen-binding proteins, increased capacity to bind fibrinogen, and increased expression of methicillin resistance genes. Our findings demonstrate thatagrfunctionality is critical for CA-MRSA disease and indicate that an adaptation of theagrregulon contributed to the evolution of highly pathogenic CA-MRSA.

scholarly journals Analysis of Staphylococcal Cassette Chromosomemecin BD GeneOhm MRSA Assay-Negative Strains

2013 ◽  
Vol 57 (6) ◽  
pp. 2890-2891 ◽  
Author(s):  
Meng Zhang ◽  
Teruyo Ito ◽  
Shanshuang Li ◽  
Shigeki Misawa ◽  
Shigemi Kondo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
High Ratio ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Staphylococcal Cassette Chromosome

ABSTRACTThe BD GeneOhm MRSA assay could identify methicillin-resistantStaphylococcus aureus(MRSA) strains at a high ratio (97.8%). Analysis of 11 assay-negative MRSA strains suggested that insertion of non-mecstaphylococcal cassette chromosome elements (SCCs) downstream oforfX, and carriage of SCCmecs with a left extremity that cannot be detected by the kit, might lead to their being given an incorrect negative status.

scholarly journals A Novel Staphylococcal Cassette Chromosomal Element, SCCfusC, CarryingfusCandspeGin Fusidic Acid-Resistant Methicillin-Resistant Staphylococcus aureus

2013 ◽  
Vol 58 (2) ◽  
pp. 1224-1227 ◽  
Author(s):  
Yu-Tzu Lin ◽  
Jui-Chang Tsai ◽  
Hsiao-Jan Chen ◽  
Wei-Chun Hung ◽  
Po-Ren Hsueh ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fusidic Acid ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Nucleotide Sequencing ◽  
Methicillin Resistant ◽  
Content Type ◽  
High Prevalence ◽  
Flanking Regions ◽  
Staphylococcal Cassette Chromosome

ABSTRACTA high prevalence offusC(16/46, 59%) was found in fusidic acid-resistant methicillin-resistantStaphylococcus aureusisolates collected from 2008 to 2010. Nucleotide sequencing offusCand flanking regions revealed a novel staphylococcal cassette chromosome (SCC) structure, SCCfusC, which was integrated intorlmHand located upstream from SCCmec. The SCCfusCelement containedspeG, which may contribute to the polyamine resistance.

scholarly journals Dissemination of the Samecfr-Carrying Plasmid among Methicillin-Resistant Staphylococcus aureus and Coagulase-Negative Staphylococcal Isolates in China

2015 ◽  
Vol 59 (6) ◽  
pp. 3669-3671 ◽  
Author(s):  
Jia Chang Cai ◽  
Yan Yan Hu ◽  
Hong Wei Zhou ◽  
Gong-Xiang Chen ◽  
Rong Zhang
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Mobile Element ◽  
Sequence Type ◽  
Coagulase Negative Staphylococci ◽  
Methicillin Resistant ◽  
Content Type ◽  
Staphylococcal Species ◽  
Complete Sequencing ◽  
Staphylococcal Cassette Chromosome

ABSTRACTSixcfr-harboring methicillin-resistantStaphylococcus aureus(MRSA) isolates, which belonged to the same clone of sequence type 5 (ST5)-staphylococcal cassette chromosomemecelement II (SCCmecII)-spat311, were investigated in this study. Complete sequencing of acfr-carrying plasmid, pLRSA417, revealed an 8,487-bp fragment containing a Tn4001-like transposon,cfr,orf1, and ISEnfa4. This segment, first identified in an animal plasmid, pSS-01, was observed in several plasmids from clinical coagulase-negative staphylococci in China, suggesting that thecfrgene, which might originate from livestock, was located in the same mobile element and disseminated among different clinical staphylococcal species.

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