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Abstract
Methicillin-susceptible S. aureus changes to methicillin-resistant S. aureus (MRSA) upon the acquisition of staphylococcal cassette chromosome mec (SCCmec), a genomic island that encodes methicillin resistance. SCCmec elements in S. aureus are classified into different types based on the combination of mec gene complexes and ccr gene complexes, which share variations, five classes in mec and eight in ccr. To date, at least 13 types of SCCmec elements have been identified and each SCCmec type has individual characteristics. It is known that hospital-associated MRSA strains carry SCCmec elements of types, I, II, and III, and the majority of community-acquired MRSA strains carry characteristic SCCmec elements, type IV SCCmec or type V SCCmec. We herein describe multiplex PCR methods to type SCCmec elements by identifying the mec gene complex class and ccr gene complex type.
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Khan AA, Farooq J, Abid M, Zahra R. Assessment of inducible clindamycin resistance and Hyper Variable Region (HVR) of mecA gene in clinical staphylococci. Pak J Med Sci 2020; 36:136-140. [PMID: 32063947 PMCID: PMC6994918 DOI: 10.12669/pjms.36.2.665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objective: To study the prevalence of inducible clindamycin along with vancomycin and methicillin resistance and assessment of hyper variable region (HVR) of mecA gene among different clinical isolates of Staphylococcus spp. Methods: A total of 176 clinical isolates of Staphylococci were collected from Pakistan Institute of Medical Sciences (PIMS), Islamabad during 2014-2015. The sample sources were pus, blood, urine, sputum, tracheal secretions and tissue fluids. Bacterial identification was done by colony morphology and biochemical tests. Kirby-Bauer disc-diffusion method was carried out to assess the susceptibility against different antibiotics. Minimal inhibitory concentrations (MICs) were done for vancomycin resistance. Double Disk Diffusion test (D-test) was used to detect the clindamycin inducible resistance. PCR was performed to detect erm(C), mecA and HVR genes. Results: Clindamycin inducible resistance among Staphylococcal isolates was found to be 7%, whereas in S. aureus it was 4%, and in coagulase negative Staphylococci (CoNS) it was 11%. The highest resistance was observed against fosfomycin, fusidic acid and cefoxitin. Vancomycin resistance was observed in 23 isolates (13%) of Staphylococci. erm(C), mecA and HVR genes were found in 18%, 50% and 42% respectively. Conclusions: D-test must be performed routinely to avoid clindamycin failure. A high level of resistance against vancomycin in Staphylococcal isolates is a concern for public health.
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Affiliation(s)
- Amir Afzal Khan
- Amir Afzal Khan, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Jahanzaib Farooq
- Jahanzaib Farooq, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Madiha Abid
- Madiha Abid, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Rabaab Zahra
- Rabaab Zahra, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan
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Motallebi M, Jabalameli F, Beigverdi R, Emaneini M. High prevalence of direct repeat unit types of 10di, 8 h and 8i among methicillin resistant Staphylococcus aureus strains with staphylococcal cassette chromosome mec type IIIA isolated in Tehran, Iran. Antimicrob Resist Infect Control 2019; 8:50. [PMID: 30886703 PMCID: PMC6404295 DOI: 10.1186/s13756-019-0501-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 02/24/2019] [Indexed: 01/21/2023] Open
Abstract
Background The emergence of methicillin-resistant Staphylococcus aureus (MRSA) is a main concern in burn care centers worldwide. The some reports of MRSA in Iran suggested that MRSA with type SCCmec III is common among burn patients. The aim of this study was to determine the prevalence, virulence genes, and antimicrobial susceptibility of the direct repeat units (dru) types of MRSA with SCCmec IIIA isolated from burn wounds in a burn care center in Tehran, Iran. Methods In total, 165 S. aureus isolates were collected from clinical samples. In order to detect MRSA isolates, the mecA gene was amplified through the polymerase chain reaction (PCR) method. Antimicrobial susceptibility was tested using the disc agar diffusion test. Moreover, the PCR method was applied to determine SCCmec types, virulence genes, and antimicrobial resistance genes. The dru region was sequenced and thereby, dru types and dru repeats were identified. A similarity matrix was used to create minimum spanning tree (MST). Results The prevalence of MRSA was 69% (114 out of 165 isolates). Most of MRSA isolates (61 out of 114, 53.5%) were SCCmec type IIIA. All MRSA isolates were vancomycin-susceptible and more than 68% of MRSA isolates with SCCmec type IIIA were mupirocin resistant. The successful dru typing of isolates with SCCmec type IIIA revealed fourteen different dru types. There were two new dru types, namely dt10di and dt7aj. MST analysis indicated the presence of the three clusters of dt10di (cluster I), dt8i-dt8 h (cluster II), and dt11c-dt10ao-dt11dd-dt11a-dt10a (cluster III). There were significant differences between clusters I and II respecting antimicrobial resistance pattern and virulence genes. Conclusion Three main dru clusters are prevalent in the study setting. The main dru types in the setting are dt10di, dt8i, and dt8 h. Dru typing can be used to differentiate MRSA strains with SCCmec IIIA.
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Affiliation(s)
- Mitra Motallebi
- 1Infectious Diseases Research Center, Kashan University of Medical Sciences, Kashan, Iran.,2Department of Immunology and Microbiology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Fereshteh Jabalameli
- 3Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Building No. 7, 100 Poursina St., Keshavarz Blvd., Tehran, 14167-53955 Iran
| | - Reza Beigverdi
- 3Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Building No. 7, 100 Poursina St., Keshavarz Blvd., Tehran, 14167-53955 Iran
| | - Mohammad Emaneini
- 3Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Building No. 7, 100 Poursina St., Keshavarz Blvd., Tehran, 14167-53955 Iran
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Xue H, Wu Z, Li L, Li F, Wang Y, Zhao X. Coexistence of heavy metal and antibiotic resistance within a novel composite staphylococcal cassette chromosome in a Staphylococcus haemolyticus isolate from bovine mastitis milk. Antimicrob Agents Chemother 2015; 59:5788-92. [PMID: 26169408 PMCID: PMC4538546 DOI: 10.1128/aac.04831-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 07/06/2015] [Indexed: 01/07/2023] Open
Abstract
The structure of a composite staphylococcal cassette chromosome (SCC) carried by a methicillin-resistant Staphylococcus haemolyticus (NW19A) isolated from a bovine milk sample was analyzed. The formation of the circular forms of both single SCC elements and composite SCC elements was detected in NW19A. Twenty heavy metal and antibiotic resistance-related genes coexisted in this composite SCC, suggesting that these genes might be coselected under environmental pressure. The mec gene complex in NW19A, designated type C3, is different from classic C1 or C2 gene complexes structurally and likely evolves differently. Furthermore, results from alignment of the SCC composite island of NW19A with 50 related sequences from different staphylococcal strains provided additional evidence to support the notion that coagulase-negative staphylococci (CoNS) are the original host of heavy metal resistance genes among staphylococci. Given that a SCC composite island could transfer freely among different staphylococcal species from different hosts, more attention should be paid to contamination with heavy metals and antibiotics in dairy farming environments, including wastewater, soil, feces, and feed.
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Affiliation(s)
- Huping Xue
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Zhaowei Wu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Longping Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Fan Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Yiqing Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Xin Zhao
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China Department of Animal Science, McGill University, Quebec, Canada
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Singh VK, Vaish M, Johansson TR, Baum KR, Ring RP, Singh S, Shukla SK, Moskovitz J. Significance of four methionine sulfoxide reductases in Staphylococcus aureus. PLoS One 2015; 10:e0117594. [PMID: 25680075 PMCID: PMC4334518 DOI: 10.1371/journal.pone.0117594] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 12/29/2014] [Indexed: 12/28/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.
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Affiliation(s)
- Vineet K. Singh
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
- * E-mail:
| | - Manisha Vaish
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
| | - Trintje R. Johansson
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
| | - Kyle R. Baum
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
| | - Robert P. Ring
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
| | - Saumya Singh
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America
| | - Sanjay K. Shukla
- Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America
| | - Jackob Moskovitz
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, Kansas, United States of America
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Corda D, Mosca MG, Ohshima N, Grauso L, Yanaka N, Mariggiò S. The emerging physiological roles of the glycerophosphodiesterase family. FEBS J 2014; 281:998-1016. [PMID: 24373430 DOI: 10.1111/febs.12699] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 12/12/2013] [Accepted: 12/19/2013] [Indexed: 01/21/2023]
Abstract
The glycerophosphodiester phosphodiesterases are evolutionarily conserved proteins that have been linked to several patho/physiological functions, comprising bacterial pathogenicity and mammalian cell proliferation or differentiation. The bacterial enzymes do not show preferential substrate selectivities among the glycerophosphodiesters, and they are mainly dedicated to glycerophosphodiester hydrolysis, producing glycerophosphate and alcohols as the building blocks that are required for bacterial biosynthetic pathways. In some cases, this enzymatic activity has been demonstrated to contribute to bacterial pathogenicity, such as with Hemophilus influenzae. Mammalian glyerophosphodiesterases have high substrate specificities, even if the number of potential physiological substrates is continuously increasing. Some of these mammalian enzymes have been directly linked to cell differentiation, such as GDE2, which triggers motor neuron differentiation, and GDE3, the enzymatic activity of which is necessary and sufficient to induce osteoblast differentiation. Instead, GDE5 has been shown to inhibit skeletal muscle development independent of its enzymatic activity.
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Affiliation(s)
- Daniela Corda
- Institute of Protein Biochemistry, National Research Council, Naples, Italy
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Ito T, Kuwahara-Arai K, Katayama Y, Uehara Y, Han X, Kondo Y, Hiramatsu K. Staphylococcal Cassette Chromosome mec (SCCmec) analysis of MRSA. Methods Mol Biol 2014; 1085:131-148. [PMID: 24085694 DOI: 10.1007/978-1-62703-664-1_8] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Methicillin-susceptible S. aureus (MSSA) changes to methicillin-resistant S. aureus upon the acquisition of Staphylococcal Cassette Chromosome mec (SCCmec), a genomic island that encodes methicillin resistance. All SCCmec elements reported to date share four common characteristics: (1) carrying the mec gene complex (mec); (2) carrying the ccr gene complex (ccr); (3) being flanked by characteristic nucleotide sequences, inverted repeats, and direct repeats, at both ends; and (4) being integrated at the integration site sequence (ISS) for SCC, which is located at the 3'-end of orfX or at the extremity of the SCC element. SCCmec elements in S. aureus are classified into different types based on the combination of mec and ccr, which share variations, five classes in mec and eight in ccr. To date, at least 11 types of SCCmec elements have been identified. Regions other than mec and ccr within the SCCmec element are designated as "joining regions" (J-regions), which are classified into three subgroups, J1-3. Many J-region variants have been identified among the SCCmec elements of types I-V. We herein describe PCR methods to type SCCmec elements by first identifying the mec and ccr type, and then identifying genes in the J-regions.
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Affiliation(s)
- Teruyo Ito
- Department of Infection Control Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan
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Ho CM, Ho MW, Li CY, Lu JJ. Fine typing of methicillin-resistant Staphylococcus aureus isolates using direct repeat unit and staphylococcal interspersed repeat unit typing methods. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2013; 48:370-5. [PMID: 24184003 DOI: 10.1016/j.jmii.2013.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 08/21/2013] [Accepted: 08/27/2013] [Indexed: 01/20/2023]
Abstract
BACKGROUND/PURPOSE Methicillin-resistant Staphylococcus aureus (MRSA) typing is an important epidemiologic tool for monitoring trends and preventing outbreaks. However, the efficiency of various MRSA typing methods for each SCCmec MRSA isolate is rarely evaluated. MATERIALS AND METHODS A total of 157 MRSA isolates from four different regions in Taiwan were typed with five different molecular methods, including SCCmec typing, multilocus sequence typing (MLST), spa typing, mec-associated direct repeat unit (dru) copy number determination, and staphylococcal interspersed repeat unit (SIRU) profiling. RESULTS There were four SCCmec types, eight MLST types, 15 spa types, 11 dru types, and 31 SIRU profiles. The most common type determined by each molecular typing method was SCCmec III (115 isolates, 73.2%), ST239 (99 isolates, 63.1%), t037 (107 isolates, 68.2%), 14 dru copies (76 isolates, 48.4%), and SIRU profile 3013722 (102 isolates, 65%), respectively. When using the combination of MLST, spa typing, and dru copy number, ST5-t002-4 (n = 8), ST239-t037-14 (n = 68), ST59-t437-9 (n = 9), and ST59-t437-11 (n = 6) were found to be the most common types of SCCmec types II (n = 9), III (n = 115), IV (n = 21), and VT (n = 11) isolates, respectively. SCCmec type III isolates were further classified into 11 dru types. Of the 21 SCCmec type IV isolates, 14 SIRU profiles were found. Seven SIRU patterns were observed in the 11 SCCmec type VT isolates. CONCLUSION Different typing methods showed a similar Hunter-Gaston discrimination index among the 157 MRSA isolates. However, dru and SIRU typing methods had a better discriminatory power for SCCmec type III and SCCmec types IV and VT isolates, respectively, suggesting that dru and SIRU can be used to further type these isolates.
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Affiliation(s)
- Cheng-Mao Ho
- Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan; Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan; Department of Nursing, Hungkuang University, Taichung, Taiwan; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Mao-Wang Ho
- Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Chi-Yuan Li
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
| | - Jang-Jih Lu
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan; Department of Laboratory Medicine, Chang-Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kweishan, Taoyuan, Taiwan.
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Comparison of Hypervariable Region (HVR) of mecA Gene in Staphylococcus aureus Isolated From Nasal Carriers and Clinical Samples. Jundishapur J Microbiol 2013. [DOI: 10.5812/jjm.7686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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El-Mahdy TS, El-Ahmady M, Goering RV. Molecular characterization of methicillin-resistant Staphylococcus aureus isolated over a 2-year period in a Qatari hospital from multinational patients. Clin Microbiol Infect 2013; 20:169-73. [PMID: 23782067 DOI: 10.1111/1469-0691.12240] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/22/2013] [Accepted: 04/02/2013] [Indexed: 11/28/2022]
Abstract
Global spread of epidemic methicillin-resistant Staphylococcus aureus (MRSA) is an issue of increasing clinical concern especially problematic community-associated (CA) -MRSA. However, data regarding MRSA epidemiology in regions of the Middle East, including Qatar, are still insufficient. A representative subset of 61 MRSA isolates from multinational patients from hospital in Qatar during a 2-year period (2009/2010) was examined. Molecular characterization for MRSA isolates was performed by pulsed-field gel electrophoresis (PFGE), SCCmec, spa and dru typing, and PCR for the presence of the arginine catabolic mobile element and genes for the Panton-Valentine leukocidin (PVL). Prevalence of MRSA among S. aureus isolated was 176/840 (21%). Of the 61 MRSA isolates examined, three (5%) represented hospital-acquired infection. By PFGE, 32 isolates (52%) were CA-MRSA USA300 (n = 4), USA400 (n = 3), USA1100/Southwest (SW) Pacific (n = 17) and ST80-MRSA-IV (n = 8) strains. The remaining isolates were well-known healthcare-associated EMRSA-15 (n = 8) and USA800 (n = 13). Three isolates were USA900, one was USA1200 and four were unrelated to any known strains in the international database. Unexpectedly, the USA900 isolates were all positive for PVL and USA400 isolates were PVL negative. Five of the eight EMRSA-15 isolates were PVL positive. ST80-MRSA-IV and USA300 strains exhibited typical dru types (dt10a and dt9g, respectively). Eleven different spa types were observed in this study. All USA300 isolates were arginine catabolic mobile element positive. The high prevalence of CA-MRSA, especially including USA300, in this setting underscores the importance of global epidemiological monitoring to better understand and hopefully help prevent the emergence and spread of these problem pathogens in patient populations.
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Affiliation(s)
- T S El-Mahdy
- Faculty of Pharmacy, Helwan University, Cairo, Egypt; College of Clinical Pharmacy, King-Faisal University, Al Ahsa, Saudi Arabia
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Bartels MD, Boye K, Oliveira DC, Worning P, Goering R, Westh H. Associations between dru Types and SCCmec cassettes. PLoS One 2013; 8:e61860. [PMID: 23634214 PMCID: PMC3636274 DOI: 10.1371/journal.pone.0061860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/15/2013] [Indexed: 11/23/2022] Open
Abstract
Molecular typing is an important tool in the investigation of methicillin resistant Staphylococcus aureus (MRSA) outbreaks and in following the evolution of MRSA. The staphylococcal cassette chromosome mec (SCCmec) contains a hypervariable region with a variable number of 40 bp repeats named direct repeat units (dru). The dru region has been suggested as a supplementary typing method for MRSA and an international nomenclature exists. The purpose of this study was to investigate the diversity and variability of the dru region in a diverse collection of MRSA. We studied 302 MRSA isolates harbouring SCCmec types I to VI. The isolates represented a broad genetic background based on Staphylococcal protein A (spa) typing and multilocus sequence typing (MLST) and included 68 isolates (68 patients) from an outbreak with t024-ST8-IVa and 26 isolates from the same patient. Sequencing identified 53 dru types (dt) in 283 isolates, while eighteen isolates contained no dru repeats and one isolate resisted sequencing. The most common dru type, dt10a, was present in 53% of the sequenced isolates and was found in all SCCmec types, except type II. Seven (10%) of the 68 epidemiologically related patients had isolates with dru type variants indicating that dru typing is not useful as a first line epidemiological typing tool. However, MRSA isolates cultured from a single patient over a three year period exhibited a single dru type. The finding of dt10a in most SCCmec types suggests that dru and mecA originate from the same Staphylococcus species.
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Affiliation(s)
- Mette D Bartels
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.
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Ghaznavi-Rad E, Goering RV, Nor Shamsudin M, Weng PL, Sekawi Z, Tavakol M, van Belkum A, Neela V. mec-associated dru typing in the epidemiological analysis of ST239 MRSA in Malaysia. Eur J Clin Microbiol Infect Dis 2011; 30:1365-9. [PMID: 21479532 DOI: 10.1007/s10096-011-1230-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Accepted: 03/13/2011] [Indexed: 11/28/2022]
Abstract
The usefulness of mec-associated dru typing in the epidemiological analysis of methicillin-resistant Staphylococcus aureus (MRSA) isolated in Malaysia was investigated and compared with pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa and SCCmec typing. The isolates studied included all MRSA types in Malaysia. Multilocus sequence type ST188 and ST1 isolates were highly clonal by all typing methods. However, the dru typing of ST239 isolates produced the clearest discrimination between SCCmec IIIa and III isolates, yielding more subtypes than any other method. Evaluation of the discriminatory power for each method identified dru typing and PFGE as the most discriminatory, with Simpson's index of diversity (SID) values over 89%, including an isolate which was non-typeable by spa, but dru-typed as dt13j. The discriminatory ability of dru typing, especially with closely related MRSA ST239 strains (e.g., Brazilian and Hungarian), underscores its utility as a tool for the epidemiological investigation of MRSA.
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Affiliation(s)
- E Ghaznavi-Rad
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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Lemmens N, van Wamel W, Snijders S, Lesse AJ, Faden H, van Belkum A. Genomic comparisons of USA300 Staphylococcus aureus colonizating the nose and rectum of children with skin abscesses. Microb Pathog 2010; 50:192-9. [PMID: 21172415 DOI: 10.1016/j.micpath.2010.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Revised: 12/09/2010] [Accepted: 12/11/2010] [Indexed: 11/29/2022]
Abstract
USA300 Staphylococcus aureus is responsible for the current outbreak of skin abscesses in the United States. Unlike other USA types, USA300 colonizes the rectum at rates higher than the nose. The reason for the difference in colonization site preference may be related to specific adherence or attachment factors contained in the genome of these strains. Additional knowledge in this field may help design novel prophylactic and therapeutic strategies to combat staphylococcal infections. Strains of USA300 MSSA and MRSA colonizing the nose and/or rectum from children with staphylococcal skin abscesses were compared by whole genome array technology to identify bacterial genetic determinants associated with site-specific colonization. Strains isolated from different colonization sites were indistinguishable by genomic content. Site-specific colonization traits were not detected in the colonizing bacteria by this array. Either host characteristics associated with staphylococcal carriage or under represented bacterial genomic constructions need to be examined to determine the etiology of this site-specific colonization.
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Affiliation(s)
- Nicole Lemmens
- Erasmus Medical College, Department of Clinical Microbiology and Infectious Diseases, Rotterdam, The Netherlands
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Origin and molecular evolution of the determinant of methicillin resistance in staphylococci. Antimicrob Agents Chemother 2010; 54:4352-9. [PMID: 20679504 DOI: 10.1128/aac.00356-10] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important multidrug-resistant pathogens around the world. MRSA is generated when methicillin-susceptible S. aureus (MSSA) exogenously acquires a methicillin resistance gene, mecA, carried by a mobile genetic element, staphylococcal cassette chromosome mec (SCCmec), which is speculated to be transmissible across staphylococcal species. However, the origin/reservoir of the mecA gene has remained unclear. Finding the origin/reservoir of the mecA gene is important for understanding the evolution of MRSA. Moreover, it may contribute to more effective control measures for MRSA. Here we report on one of the animal-related Staphylococcus species, S. fleurettii, as the highly probable origin of the mecA gene. The mecA gene of S. fleurettii was found on the chromosome linked with the essential genes for the growth of staphylococci and was not associated with SCCmec. The mecA locus of the S. fleurettii chromosome has a sequence practically identical to that of the mecA-containing region (∼12 kbp long) of SCCmec. Furthermore, by analyzing the corresponding gene loci (over 20 kbp in size) of S. sciuri and S. vitulinus, which evolved from a common ancestor with that of S. fleurettii, the speciation-related mecA gene homologues were identified, indicating that mecA of S. fleurettii descended from its ancestor and was not recently acquired. It is speculated that SCCmec came into form by adopting the S. fleurettii mecA gene and its surrounding chromosomal region. Our finding suggests that SCCmec was generated in Staphylococcus cells living in animals by acquiring the intrinsic mecA region of S. fleurettii, which is a commensal bacterium of animals.
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Identification of a novel transposon (Tn6072) and a truncated staphylococcal cassette chromosome mec element in methicillin-resistant Staphylococcus aureus ST239. Antimicrob Agents Chemother 2010; 54:3347-54. [PMID: 20479198 DOI: 10.1128/aac.00001-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel composite transposon (Tn6072) resembling staphylococcal cassette chromosome mercury (SCCHg) was identified in a collection of sequence type (ST) 239 methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates from Romanian hospitals. Tn6072 is homologous to the 5' region of SCCHg found in staphylococcal cassette chromosome mec (SCCmec) type III prototype strain 85/2082 but lacks the characteristic mer operon. SCCHg has previously been reported to integrate downstream of orfX, at the same chromosomal location as SCCmec. Tn6072, by contrast, is demarcated by two IS431 elements, flanked by 8-bp direct repeats, and inserted upstream of the origin of replication, within an open reading frame homologous to SAR2700 of S. aureus strain MRSA252. Analysis of a geographically and temporally diverse collection of 111 strains from the ST239 clonal group uncovered 11 additional strains harboring Tn6072, demonstrating a lineage-specific insertion pattern. Complete sequence analysis of the SCCmec regions of two representative Romanian strains (BK16704, BK16691) revealed two additional novel structures derived from a type III SCCmec background. BK16704 possesses an SCCmec 3A.1.4 structure, with an IS256 insertion downstream of the right chromosomal junction. In contrast, the SCCmec element of BK16691 is truncated downstream of the mec gene complex, with a 24-kb deletion encompassing the right chromosomal junction and an inverted downstream IS256 element. This structure, tentatively named "psiSCCmec16691," confers methicillin resistance but lacks most of the J1/J2 region, including the ccr gene complex. Taken together, these findings provide evidence for the continuing evolution of SCC elements, as well as the ST239 clonal group.
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16
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Goering RV, Morrison D, Al-Doori Z, Edwards GFS, Gemmell CG. Usefulness of mec-associated direct repeat unit (dru) typing in the epidemiological analysis of highly clonal methicillin-resistant Staphylococcus aureus in Scotland. Clin Microbiol Infect 2008; 14:964-9. [PMID: 18828855 DOI: 10.1111/j.1469-0691.2008.02073.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The incidence of the epidemic methicillin-resistant Staphylococcus aureus (EMRSA) strains EMRSA-15 and EMRSA-16 in Scotland has increased dramatically, now accounting for c. 70% and c. 20% of isolates, respectively. Epidemiological tracking of these EMRSA strains is difficult, as c. 50% of EMRSA-15 and c. 35% of EMRSA-16 isolates are indistinguishable using pulsed-field gel electrophoresis (PFGE) and other typing methods. The usefulness of mec-associated direct repeat unit (dru) sequence analysis as a more sensitive approach to tracking the persistence and spread of these 'clonal' EMRSA strains in Scotland was evaluated. Analysis of 47 EMRSA-15 and 57 EMRSA-16 isolates (including two separately cultured isolates of the Harmony collection type strain) obtained from 22 hospital laboratories over an 8-year period (1997-2005) revealed 13 and 12 different dru types, respectively. Whereas some types appeared to be endemic in multiple hospitals, subtypes that may represent specific strain movement among hospitals in a given geographical region were identified in other instances. These results suggest that mec-associated dru typing may have potential for identifying and tracking specific subtypes of otherwise indistinguishable epidemic MRSA isolates such as those in Scotland.
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Affiliation(s)
- R V Goering
- Department of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, NE 68178, USA.
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17
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Stepán J, Pantůcek R, Doskar J. Molecular diagnostics of clinically important staphylococci. Folia Microbiol (Praha) 2008; 49:353-86. [PMID: 15530002 DOI: 10.1007/bf03354664] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Bacterial species of the genus Staphylococcus known as important human and animal pathogens are the cause of a number of severe infectious diseases. Apart from the major pathogen Staphylococcus aureus, other species until recently considered to be nonpathogenic may also be involved in serious infections. Rapid and accurate identification of the disease-causing agent is therefore prerequisite for disease control and epidemiological surveillance. Modern methods for identification and typing of bacterial species are based on genome analysis and have many advantages compared to phenotypic methods. The genotypic methods currently used in molecular diagnostics of staphylococcal species, particularly of S. aureus, are reviewed. Attention is also paid to new molecular methods with the highest discriminatory power. Efforts made to achieve interlaboratory reproducibility of diagnostic methods are presented.
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Affiliation(s)
- J Stepán
- Department of Genetics and Molecular Biology, Faculty of Science, Masaryk University, 611 37 Brno, Czechia
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18
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Variability in SCCmecN1 spreading among injection drug users in Zurich, Switzerland. BMC Microbiol 2007; 7:62. [PMID: 17605795 PMCID: PMC3225876 DOI: 10.1186/1471-2180-7-62] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 07/02/2007] [Indexed: 12/04/2022] Open
Abstract
Background An extremely low level methicillin resistant Staphylococcus aureus (MRSA) belonging to ST45, circulates among intravenous drug users in the Zurich area. This clone can be misinterpreted as an MSSA by phenotypic oxacillin resistance tests, although it carries a staphylococcal cassette chromosome mec (SCCmec) element encoding a functional mecA gene and it produces PBP2a. Results This clone carried a new 45.7-kb element, termed SCCmecN1, containing a class B mec complex (mecA-ΔmecR1::IS1272), a truncated Tn4003 harbouring the dfrA gene, and a fusB1 gene, conferring methicillin, trimethoprim and low level fusidic acid resistance, respectively. In addition to the two insertion site sequences (ISS) framing the SCCmec, a third ISS (ISS*) was identified within the element. SCCmecN1 also harboured two distinct ccrAB complexes belonging to the class 4 subtype, both of which were shown to be active and to be able to excise the SCCmecN1 or parts thereof. Slight variations in the SmaI-PFGE pattern of the clinical MRSA isolates belonging to this clone were traced back to differences in the sizes of the SCCmec J2 regions and/or to a 6.4-kb deletion extending from ISS* to the right end ISS. This latter deletion led to a variant right SCCmec-chromosomal junction site. MRSA clones carrying the shorter SCCmec with the 6.4-kb deletion were usually ciprofloxacin resistant, while strains with the complete SCCmecN1 were co-trimoxazole resistant or had no additional resistances. This suggested that the genetic backbone of the host S. aureus, although identical by PFGE pattern, had at some stage diverged with one branch acquiring a sulfonomide resistance mutation and the other ciprofloxacin resistance. Conclusion This description of the structure and variations of SCCmecN1 will allow for quicker and easier molecular detection of this clone and monitoring of its spread.
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Patton-Vogt J. Transport and metabolism of glycerophosphodiesters produced through phospholipid deacylation. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1771:337-42. [PMID: 16781190 DOI: 10.1016/j.bbalip.2006.04.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 04/20/2006] [Accepted: 04/26/2006] [Indexed: 10/25/2022]
Abstract
Phospholipid deacylation results in the formation of glycerophosphodiesters and free fatty acids. In Saccharomyces cerevisiae, four gene products with phospholipase B (deacylating) activity have been characterized (PLB1, PLB2, PLB3, NTE1), and those activities account for most, if not all, of the glycerophosphodiester production observed to date. The glycerophosphodiesters themselves are hydrolyzed into glycerol-3-phosphate and the corresponding alcohol by glycerophosphodiester phosphodiesterases. Although only one glycerophosphodiester phosphodiesterase-encoding gene (GDE1) has been characterized in S. cerevisiae, others certainly exist. Both internal and external glycerophosphodiesters (primarily glycerophosphocholine and glycerophosphoinositol) are formed as a result of phospholipid turnover in S. cerevisiae. A permease encoded by the GIT1 gene imports extracellular glycerophosphodiesters across the plasma membrane, where their hydrolytic products can provide crucial nutrients such as inositol, choline, and phosphate to the cell. The importance of this metabolic pathway in various aspects of S. cerevisiae cell physiology is being explored.
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Affiliation(s)
- Jana Patton-Vogt
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
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20
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Boyle-Vavra S, Ereshefsky B, Wang CC, Daum RS. Successful multiresistant community-associated methicillin-resistant Staphylococcus aureus lineage from Taipei, Taiwan, that carries either the novel Staphylococcal chromosome cassette mec (SCCmec) type VT or SCCmec type IV. J Clin Microbiol 2005; 43:4719-30. [PMID: 16145133 PMCID: PMC1234068 DOI: 10.1128/jcm.43.9.4719-4730.2005] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Revised: 03/27/2005] [Accepted: 05/22/2005] [Indexed: 11/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) isolates carry the methicillin resistance gene (mecA) on a horizontally transferred genetic element called the staphylococcal chromosome cassette mec (SCCmec). Community-acquired MRSA (CAMRSA) isolates usually carry SCCmec type IV. We previously reported that 76% of 17 CAMRSA isolates (multilocus sequence type 59) obtained from pediatric patients with skin and soft tissue infections (SSTI) from Taipei did not carry SCCmec types I to IV. We used DNA sequence analysis to determine that the element harbored by these nontypeable isolates is a novel subtype of SCCmec V called SCCmec V(T.) It contains a ccrC recombinase gene variant (ccrC2) and mec complex C2. One SSTI isolate contained molecular features of SCCmec IV but also contained ccrC2 (a feature of SCCmec V(T)), suggesting that it may harbor a composite SCCmec element. The genes lukS-PV and lukF-PV encoding the Panton-Valentine leukocidin (PVL) were present in all CAMRSA SSTI isolates whether they contained SCCmec type IV or V(T). SCCmec V(T) was also present in 5 of 34 (14.7%) CAMRSA colonization isolates collected from healthy children from Taipei who lacked MRSA risk factors. Four (80%) of the these isolates contained lukS-PV and lukF-PV, as did 1 of 27 (3.7%) SCCmec IV-containing colonization isolates. A total of 63% (10 of 16) of the SSTI isolates and 61.7% (21 of 34) of the colonization isolates tested were resistant to at least four classes of non-beta-lactam antimicrobials. SCCmec V(T) is a novel SCCmec variant that is found in multiply resistant CAMRSA strains with sequence type 59 in Taipei in association with the PVL leukotoxin genes.
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Affiliation(s)
- Susan Boyle-Vavra
- Department of Pediatrics, Section of Infectious Diseases, University of Chicago, IL, 60637, USA.
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21
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Strandén A, Frei R, Widmer AF. Molecular typing of methicillin-resistant Staphylococcus aureus: can PCR replace pulsed-field gel electrophoresis? J Clin Microbiol 2003; 41:3181-6. [PMID: 12843061 PMCID: PMC165370 DOI: 10.1128/jcm.41.7.3181-3186.2003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pulsed-field gel electrophoresis (PFGE) is considered the "gold standard" for molecular typing of methicillin-resistant Staphylococcus aureus (MRSA). However, the method is time-consuming and expensive, and its discriminatory power may not be necessary in outbreak situations. We used a rapid multiplex PCR-based method with published primers and compared the results with those obtained by PFGE. A total of 75 clinical isolates were typed: 59 strains originated from our prospectively collected clinical strains and were epidemiologically unrelated; 16 strains came from an outbreak that was epidemiologically well defined in time and space. A primer mix of the spa gene, the coa gene, and the hypervariable region adjacent to mecA gene was used for multiplex PCR. Both PFGE and PCR clustered the 75 strains into 41 different genotypes. Concordance of the results was 100% for strains originating from the outbreak. Overall, both methods produced concordant results in 72% of cases. A total of 16% were clustered together by PFGE, but not by PCR and 12% were clustered together by PCR but not by PFGE, respectively. The turnaround time was only 8 h for PCR but 5 days for PFGE. This PCR-based method is excellent for rapid and inexpensive typing of MRSA in an outbreak setting, but the discriminatory power and reproducibility are still insufficient to replace PFGE in longitudinal studies in the endemic setting.
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Affiliation(s)
- A Strandén
- Division of Hospital Epidemiology, University Hospital Basel, CH-3031 Basel, Switzerland
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22
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Ito T, Okuma K, Ma XX, Yuzawa H, Hiramatsu K. Insights on antibiotic resistance of Staphylococcus aureus from its whole genome: genomic island SCC. Drug Resist Updat 2003; 6:41-52. [PMID: 12654286 DOI: 10.1016/s1368-7646(03)00003-7] [Citation(s) in RCA: 273] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Staphylococci are ubiquitous colonizers of the skin and mucous membranes and Staphylococcus aureus is the most pathogenic species. The spread of antibiotic resistance among S. aureus strains is a major concern in the treatment of staphylococcal infections. Acquisition of resistance may involve mutation of a bacterial gene on the chromosome or transfer of a resistance gene from other organisms by some form of genetic exchange (conjugation, transduction, or transformation). Completion of whole genome sequences of three methicillin-resistant S. aureus (MRSA) strains has provided us a bird's-eye view of the distribution of the mobile genetic elements in the bacterial chromosome that encode antibiotic resistance as well as pathogenicity in S. aureus.
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Affiliation(s)
- Teruyo Ito
- Department of Bacteriology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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23
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Nishi J, Yoshinaga M, Miyanohara H, Kawahara M, Kawabata M, Motoya T, Owaki T, Oiso S, Kawakami M, Kamewari S, Koyama Y, Wakimoto N, Tokuda K, Manago K, Maruyama I. An epidemiologic survey of methicillin-resistant Staphylococcus aureus by combined use of mec-HVR genotyping and toxin genotyping in a university hospital in Japan. Infect Control Hosp Epidemiol 2003; 23:506-10. [PMID: 12269447 DOI: 10.1086/502097] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To evaluate the usefulness of an assay using two polymerase chain reaction-based genotyping methods in the practical surveillance of methicillin-resistant Staphylococcus aureus (MRSA). METHODS Nosocomial infection and colonization were surveyed monthly in a university hospital in Japan for 20 months. Genotyping with mec-HVR is based on the size of the mec-associated hypervariable region amplified by polymerase chain reaction. Toxin genotyping uses a multiplex polymerase chain reaction method to amplify eight staphylococcal toxin genes. RESULTS Eight hundred nine MRSA isolates were classified into 49 genotypes. We observed differing prevalences of genotypes for different hospital wards, and could rapidly demonstrate the similarity of genotype for outbreak isolates. The incidence of genotype D: SEC/TSST1 was significantly higher in isolates causing nosocomial infections (49.5%; 48 of 97) than in nasal isolates (31.4%; 54 of 172) (P = .004), suggesting that this genotype may represent the nosocomial strains. CONCLUSION The combined use of these two genotyping methods resulted in improved discriminatory ability and should be further investigated.
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Affiliation(s)
- Junichiro Nishi
- Kagoshima University Hospital, Infection Control Team, Japan
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24
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Huygens F, Nimmo GR, Schooneveldt J, Munckhof WJ, Giffard PM. Genotyping of methicillin-resistant Staphylococcus aureus by assaying for the presence of variable elements associated with mecA. J Clin Microbiol 2002; 40:3093-7. [PMID: 12149390 PMCID: PMC120667 DOI: 10.1128/jcm.40.8.3093-3097.2002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The region surrounding mecA in methicillin-resistant Staphylococcus aureus (MRSA) is highly variable. We describe an approach for the rapid genotyping of MRSA by assaying for the presence or absence of variable or mobile elements previously shown to be associated with the mecA region.
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Affiliation(s)
- Flavia Huygens
- Cooperative Research Centre for Diagnostics, Queensland University of Technology, Brisbane, Queensland 4001, Australia
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25
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Senna JPM, Pinto CA, Carvalho LPS, Santos DS. Comparison of pulsed-field gel electrophoresis and PCR analysis of polymorphisms on the mec hypervariable region for typing methicillin-resistant Staphylococcus aureus. J Clin Microbiol 2002; 40:2254-6. [PMID: 12037102 PMCID: PMC130718 DOI: 10.1128/jcm.40.6.2254-2256.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two hundred fifty-four methicillin-resistant Staphylococcus aureus (MRSA) strains typed by pulsed-field gel electrophoresis (PFGE) were tested by PCR for the mec-associated hypervariable region (HVR-PCR) to determine their number of direct repeat units (DRUs). Eight different groups of repeats were found among the MRSA strains and compared to 28 pulsotypes classified by PFGE. Some MRSA strains belonging to the same pulsotype showed different numbers of DRUs. HVR-PCR was rapid, easy to perform, and reproducible and has the ability to obtain an unambiguous positive result for each isolate analyzed. However, this technique shows a discriminatory power inferior to that of PFGE. We conclude that PFGE is a more reliable method of typing MRSA than HVR-PCR.
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Affiliation(s)
- J P M Senna
- Group of Molecular and Functional Microbiology, Department of Molecular Biology and Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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26
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Salmenlinna S, Lyytikäinen O, Vuopio-Varkila J. Community-acquired methicillin-resistant Staphylococcus aureus, Finland. Emerg Infect Dis 2002; 8:602-7. [PMID: 12023917 PMCID: PMC2738488 DOI: 10.3201/eid0806.010313] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is no longer only hospital acquired. MRSA is defined as community acquired if the MRSA-positive specimen was obtained outside hospital settings or within 2 days of hospital admission, and if it was from a person who had not been hospitalized within 2 years before the date of MRSA isolation. To estimate the proportion of community-acquired MRSA, we analyzed previous hospitalizations for all MRSA-positive persons in Finland from 1997 to 1999 by using data from the National Hospital Discharge Register. Of 526 MRSA-positive persons, 21% had community-acquired MRSA. Three MRSA strains identified by phage typing, pulsed-field gel electrophoresis, and ribotyping were associated with community acquisition. None of the strains were multiresistant, and all showed an mec hypervariable region hybridization pattern A (HVR type A). None of the epidemic multiresistant hospital strains were prevalent in nonhospitalized persons. Our population-based data suggest that community-acquired MRSA may also arise de novo, through horizontal acquisition of the mecA gene.
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Affiliation(s)
- Saara Salmenlinna
- Department of Microbiology, National Public Health Institute, Helsinki, Finland.
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27
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Nahvi MD, Fitzgibbon JE, John JF, Dubin DT. Sequence analysis of dru regions from methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococcal isolates. Microb Drug Resist 2001; 7:1-12. [PMID: 11310798 DOI: 10.1089/107662901750152684] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Methicillin-resistance in staphylococci results from expression of mecA, which occurs in a larger region of DNA (the mec region) lacking counterpart in susceptible cells. The mec region harbors in addition a highly polymorphic element, the dru (direct repeat unit) segment, which in an early S. aureus strain, BB270, was found to contain 10 imperfect 40 base-pair repeats. We have explored the utility of direct sequencing of dru segments for discriminating among strains of methicillin-resistant S. aureus (MRSA) and coagulase-negative staphylococci (MRCNS). We sequenced dru segments of 24 clinical isolates of MRSA, and 15 of MRCNS, and reexamined strain BB270. Six S. aureus and 2 S. epidermidis isolates were found to have deletions which removed all drus. The other strains were found to have multiple contiguous dru repeats of precisely 40 bp. Analysis of these strains plus dru segment sequence from 4 recent reports yielded 18 unique dru segment sequences (designated "dru types") differing in numbers of repeats and/or sequences of particular repeats. Dru typing was more discriminating than sequencing of non-mec region genes, including a repeat-containing segment (spa Xr) of the S. aureus protein A gene. Yet dru type was sufficiently stable to register epidemiological clusters. Dru sequencing is a useful tool for tracking methicillin-resistant lineages of S. aureus and CNS.
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Affiliation(s)
- M D Nahvi
- Department of Medicine, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
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28
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Katayama Y, Ito T, Hiramatsu K. Genetic organization of the chromosome region surrounding mecA in clinical staphylococcal strains: role of IS431-mediated mecI deletion in expression of resistance in mecA-carrying, low-level methicillin-resistant Staphylococcus haemolyticus. Antimicrob Agents Chemother 2001; 45:1955-63. [PMID: 11408208 PMCID: PMC90585 DOI: 10.1128/aac.45.7.1955-1963.2001] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2000] [Accepted: 04/06/2001] [Indexed: 11/20/2022] Open
Abstract
We report on the structural diversity of mecA gene complexes carried by 38 methicillin-resistant Staphylococcus aureus and 91 methicillin-resistant coagulase-negative Staphylococcus strains of seven different species with a special reference to its correlation with phenotypic expression of methicillin resistance. The most prevalent and widely disseminated mec complex had the structure mecI-mecR1-mecA-IS431R (or IS431mec), designated the class A mecA gene complex. In contrast, in S. haemolyticus, mecA was bracketed by two copies of IS431, forming the structure IS431L-mecA-IS431R. Of the 38 S. haemolyticus strains, 5 had low-level methicillin resistance (MIC, 1 to 4 mg/liter) and characteristic heterogeneous methicillin resistance as judged by population analysis. In these five strains, IS431L was located to the left of an intact mecI gene, forming the structure IS431L-class A mecA-gene complex. In other S. haemolyticus strains, IS431L was associated with the deletion of mecI and mecR1, forming the structure IS431L-DeltamecR1-mecA-IS431mec, designated the class C mecA gene complex. Mutants with the class C mecA gene complex were obtained in vitro by selecting strain SH621, containing the IS431L-class A mecA gene complex with low concentrations of methicillin (1 and 3 mg/liter). The mutants had intermediate level of methicillin resistance (MIC, 16 to 64 mg/liter). The mecA gene transcription was shown to be derepressed in a representative mutant strain, SH621-37. Our study indicated that the mecI-encoded repressor function is responsible for the low-level methicillin resistance of some S. haemolyticus clinical strains and that the IS431-mediated mecI gene deletion causes the expression of methicillin resistance through the derepression of mecA gene transcription.
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Affiliation(s)
- Y Katayama
- Department of Bacteriology, Faculty of Medicine, Juntendo University, Tokyo, Japan
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29
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Salmenlinna S, Vuopio-Varkila J. Recognition of two groups of methicillin-resistant Staphylococcus aureus strains based on epidemiology, antimicrobial susceptibility, hypervariable-region type, and ribotype in Finland. J Clin Microbiol 2001; 39:2243-7. [PMID: 11376064 PMCID: PMC88118 DOI: 10.1128/jcm.39.6.2243-2247.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2001] [Accepted: 03/17/2001] [Indexed: 11/20/2022] Open
Abstract
Epidemiological evidence suggests that some methicillin-resistant Staphylococcus aureus (MRSA) strains are more prone to dissemination than others. We studied 72 MRSA strains, collected through nationwide MRSA surveillance in 1992 through 1999 and known to be either (i) sporadic, (ii) local outbreak strains spread within one hospital, or (iii) epidemic strains spread among hospitals, by antimicrobial susceptibility testing, hybridization of the mec hypervariable region (HVR), and ribotyping. Our results show that two main groups can be identified among these strains. The first group includes mainly nonepidemic, nonmultiresistant MRSA strains showing a specific mec HVR hybridization pattern, A, in combination with a variety of ribotypes. The other group includes multiresistant strains with mec HVR hybridization pattern B or C in association with closely related ribotype a or b. Sixty-four percent (9 of 14) of Finnish epidemic MRSA strains belong to the latter group. These findings support the existence of differences in epidemic potential among MRSA strains.
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Affiliation(s)
- S Salmenlinna
- National Public Health Institute, Department of Bacteriology, Mannerheimintie 166, 00300 Helsinki, Finland.
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30
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Gürtler V, Barrie HD, Mayall BC. Use of denaturing gradient gel electrophoresis to detect mutation in VS2 of the 16S-23S rDNA spacer amplified from Staphylococcus aureus isolates. Electrophoresis 2001; 22:1920-4. [PMID: 11465489 DOI: 10.1002/1522-2683(200106)22:10<1920::aid-elps1920>3.0.co;2-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To develop a double gradient denaturing gradient gel electrophoresis (DG-DGGE) based typing method that rapidly and accurately types clinical isolates of Staphylococcus aureus, the VS2 region of the 16S-23S rRNA spacer region (ISR) was chosen because of its potential high variation. The VS2 region was amplified with a 40-mer GC-clamp attached to the 5'-end of the reverse primer. The 145 bp PCR product was then separated by DG-DGGE using denaturant concentrations of 25-40% and polyacrylamide concentrations of 6-12%. Of the five mutations identified in 336 S. aureus isolates, one mutation was found to be highly specific for 161/171 (94%) of methicillin-resistant S. aureus (MRSA) isolates from different geographic locations and isolation times. This same mutation was found in 15/160 (9%) of penicillin- or methicillin-sensitive S. aureus isolates. In some isolates two mutations occured together in the one genome suggesting some S. aureus isolates have two copies of VS2. In these 336 isolates nine genotypes with different combinations of the five mutations were identified. In 18 coagulase-negative staphylococci (CNS), the MRSA-specific mutation was found along with two other mutations in all isolates demonstrating consistent differences in the presence of these mutations between CNS and S. aureus. The marked differences in VS2 sequences found between MRSA, methicillin- or penicillin-sensitive S. aureus (SSA), and CNS by DGGE in the present study may be useful in evolutionary studies and in the development of a specific assay for MRSA from clinical specimens.
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Affiliation(s)
- V Gürtler
- Department of Microbiology, Austin & Repatriation Medical Centre, Heidelberg, Victoria, Australia.
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31
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Wichelhaus TA, Hunfeld KP, Böddinghaus B, Kraiczy P, Schäfer V, Brade V. Rapid molecular typing of methicillin-resistant Staphylococcus aureus by PCR-RFLP. Infect Control Hosp Epidemiol 2001; 22:294-8. [PMID: 11428440 DOI: 10.1086/501903] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To establish a new, rapid, and reliable genotypic fingerprinting technique for methicillin-resistant Staphylococcus aureus (MRSA) typing in routine epidemiological surveillance. DESIGN The method is based on polymerase chain reaction (PCR) restriction fragment-length polymorphism (RFLP) following HaeII digestion of simultaneously amplified parts of the protein A gene, the coagulase gene, and the hypervariable region adjacent to mecA. A total of 46 MRSA initial isolates were analyzed, including 14 isolates from five countries; the six German epidemic strains; 16 isolates from the Frankfurt metropolitan area, which were known to be heterogeneous by pulsed-field gel electrophoresis (PFGE); and 10 isolates obtained during three epidemics, all of which displayed an identical genotype. RESULTS Restriction analysis by PCR-RFLP permitted discrimination of 10 of 14 international isolates, all six German epidemic strains, and 15 of 16 national isolates. It also confirmed the homogeneous character of the 10 outbreak isolates. CONCLUSIONS This new and rapid PCR-RFLP typing method is an attractive tool in routine epidemiological surveillance. Its impressive characteristics are ease of performance and interpretation, while at the same time guaranteeing good discriminatory power, reproducibility, and typeability.
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Affiliation(s)
- T A Wichelhaus
- Institute of Medical Microbiology, University Hospital of Frankfurt, Frankfurt am Main, Germany
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32
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Witte W, Werner G, Cuny C. Subtyping of MRSA isolates belonging to a widely disseminated clonal group by polymorphism of the dru sequences in mec-associated DNA. Int J Med Microbiol 2001; 291:57-62. [PMID: 11403412 DOI: 10.1078/1438-4221-00116] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During the past 7 years the "Berlin epidemic MRSA" has spread throughout whole Germany. SmaI macrorestriction patterns of this clonal group are rather stable as are the length polymorphisms at the 3' end of the coagulase gene and the x-region of spa. However, the dru region (direct repeat units) of mec-associated DNA exhibits a length polymorphism due to deletion of one or more direct repeat units. Five different subclones could be discriminated by dru region length polymorphism. Location of deletions and of a few point mutations allow a delineation of these subclones.
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Affiliation(s)
- W Witte
- Robert Koch Institute, Wernigerode Branch, Germany.
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33
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Oliveira DC, Crisóstomo I, Santos-Sanches I, Major P, Alves CR, Aires-de-Sousa M, Thege MK, de Lencastre H. Comparison of DNA sequencing of the protein A gene polymorphic region with other molecular typing techniques for typing two epidemiologically diverse collections of methicillin-resistant Staphylococcus aureus. J Clin Microbiol 2001; 39:574-80. [PMID: 11158109 PMCID: PMC87778 DOI: 10.1128/jcm.39.2.574-580.2001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to compare the recently developed typing approach for methicillin-resistant Staphylococcus aureus (MRSA) based on the DNA sequencing of the protein A gene polymorphic region (spaA typing) with a combination of three well-established molecular typing techniques: ClaI-mecA vicinity polymorphisms, ClaI-Tn554 insertion patterns, and SmaI pulsed-field gel electrophoresis (PFGE) profiles. In order to evaluate the applicability of this typing technique in different types of studies, two groups of MRSA clinical isolates were analyzed: a collection of 185 MRSA isolates circulating in Hungary recovered from 17 hospitals in seven cities during a 3-year period (1994 through 1996), and a selection of 53 MRSA strains isolated in a single hospital in Hungary between 1997 and 1998. The 238 MRSA clinical strains from Hungary were first classified in clonal types (defined as ClaI-mecA::ClaI-Tn554::SmaI-PFGE patterns), and 65 of the 238 strains, representing major MRSA clones and some sporadic clones, were further analyzed by spaA typing. Our results showed that the lineages most recently introduced in the hospital setting showed little variability in spaA types, whereas the MRSA clones circulating for a longer period of time and spread among several hospitals showed a higher degree of variability. The implementation of the spaA typing method was straightforward, and the results obtained were reproducible, unambiguous, and easily interpreted. This method seems to be adequate for outbreak investigations but should be complemented with other techniques in long-term surveillance or in studies comparing distant clonal lineages.
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Affiliation(s)
- D C Oliveira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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34
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Oliveira DC, Wu SW, de Lencastre H. Genetic organization of the downstream region of the mecA element in methicillin-resistant Staphylococcus aureus isolates carrying different polymorphisms of this region. Antimicrob Agents Chemother 2000; 44:1906-10. [PMID: 10858352 PMCID: PMC89983 DOI: 10.1128/aac.44.7.1906-1910.2000] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2000] [Accepted: 04/11/2000] [Indexed: 11/20/2022] Open
Abstract
We describe here the genetic organization of the mec element downstream of the mecA gene in 34 different methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates carrying 13 of the most frequent polymorphisms of mecA and representing the major epidemic clones of MRSA. All polymorphisms carried three common genetic elements: the hypervariable region, a copy of IS431, and a unique 2-kb sequence (downstream constant segment, or dcs) for which no homologous sequences are found in data banks. Polymorphisms of the downstream region were shown to be caused by the presence of linearized plasmids flanked by insertion sequences (pUB110, pT181, and pI258) and the autonomous insertion sequence IS256.
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Affiliation(s)
- D C Oliveira
- Molecular Genetics Unit, Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, Oeiras, Portugal
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35
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Ito T, Katayama Y, Hiramatsu K. Cloning and nucleotide sequence determination of the entire mec DNA of pre-methicillin-resistant Staphylococcus aureus N315. Antimicrob Agents Chemother 1999; 43:1449-58. [PMID: 10348769 PMCID: PMC89295 DOI: 10.1128/aac.43.6.1449] [Citation(s) in RCA: 302] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/1999] [Accepted: 04/06/1999] [Indexed: 11/20/2022] Open
Abstract
In methicillin-resistant Staphylococcus aureus, the methicillin resistance gene mecA is localized within a large chromosomal region which is absent in the methicillin-susceptible S. aureus chromosome. The region, designated mec DNA, is speculated to have originated from the genome of another bacterial species and become integrated into the chromosome of the S. aureus cell in the past. We report here cloning and determination of the structure of the entire mec DNA sequence from a Japanese S. aureus strain, N315. The mec DNA was found to be 51,669 bp long, including terminal inverted repeats of 27 bp and a characteristic pair of direct repeat sequences of 15 bp each: one is situated in the right extremity of mec DNA, and the other is situated outside the mec DNA and abuts the left boundary of mec DNA. The integration site of mec DNA was found to be located in an open reading frame (ORF) of unknown function, designated orfX. Clusters of antibiotic resistance genes were noted in mec DNA carried by transposon Tn554 and an integrated copy of plasmid pUB110. Both the transposon and plasmid were integrated in the proximity of the mecA gene, the latter being flanked by a pair of insertion sequence IS431 elements. Many ORFs other than those encoding antibiotic resistance were considered nonfunctional because of the acquired mutations or partial deletions found in the ORFs. Two ORFs potentially encoding novel site-specific recombinases were found in mec DNA. However, there was no ORF that might encode mec DNA-specific transposase or integrase proteins, indicating that the mec DNA is not a transposon or a bacteriophage in nature.
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Affiliation(s)
- T Ito
- Department of Bacteriology, Juntendo University, Tokyo, Japan
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36
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Fey PD, Climo MW, Archer GL. Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci. Antimicrob Agents Chemother 1998; 42:306-12. [PMID: 9527777 PMCID: PMC105405 DOI: 10.1128/aac.42.2.306] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/1997] [Accepted: 11/20/1997] [Indexed: 02/07/2023] Open
Abstract
mecA, the gene that mediates methicillin resistance, and its accompanying mec locus DNA, insert near the gyrA gene in Staphylococcus aureus. To investigate whether there is a similar relationship between mecA and gyrA in coagulase-negative staphylococci (CNS), mecA- and gyrA-specific DNA fragments were used to probe methicillin-resistant isolates of Staphylococcus epidermidis (MRSE) (n = 11) and Staphylococcus haemolyticus (MRSH) (n = 11). The gyrA probe hybridized to the same SmaI DNA fragment as the mecA probe in all strains tested. However, since the size of the SmaI fragments containing mecA and gyrA varied from 73 to 600 kb, the distance between the two genes was determined more precisely. Cloned mecA or gyrA fragments plus vector sequences each containing a SmaI site were introduced into the chromosome of three isolates each of MRSE and methicillin-resistant S. aureus (MRSA), and the sizes of the generated SmaI fragments were determined by pulsed-field gel electrophoresis. The distance between gyrA and mecA was found to be between 38 and 42 kb in both MRSE and MRSA, and the two genes were in the same relative orientation in all strains. Restriction fragment length polymorphism (RFLP) patterns around the gyrA gene in CNS were identical, but species specific, for all 10 MRSE and 10 MRSH isolates examined. In contrast, 8 of 11 methicillin-susceptible S. epidermidis isolates and 7 of 7 methicillin-susceptible S. haemolyticus isolates had different gyrA RFLP patterns. These data show that mecA is site and orientation specific, relative to gyrA, in both MRSE and MRSA. In addition, the local environment around gyrA in methicillin-resistant CNS, in contrast to methicillin-susceptible isolates, is similar, suggesting clonality or the requirement for specific DNA sequences with which the mec complex must interact for chromosomal integration to occur.
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Affiliation(s)
- P D Fey
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0049, USA
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37
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Wu S, de Lencastre H, Tomasz A. Genetic organization of the mecA region in methicillin-susceptible and methicillin-resistant strains of Staphylococcus sciuri. J Bacteriol 1998; 180:236-42. [PMID: 9440511 PMCID: PMC106877 DOI: 10.1128/jb.180.2.236-242.1998] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A homolog of the Staphylococcus aureus methicillin resistance gene mecA was recently shown to be ubiquitous in independent isolates of the animal species Staphylococcus sciuri. The mecA gene homolog and regions flanking it were cloned and sequenced from four strains of S. sciuri: strain K1 (ATCC 29062), a representative of S. sciuri subsp. sciuri; two strains (K3 and K8) representing S. sciuri subsp. rodentius; and strain K11, a representative of S. sciuri subsp. carnaticum. Strains K1 and K11 were susceptible to methicillin, while strains K3 and K8 showed heterogeneous resistance. The mecA genes of strains K1 and K11 and one of the two copies of mecA (mecA1) present in strain K3 had virtually identical DNA sequences in the mecA gene and were similar in genetic organization in the flanking regions. In contrast, the single copy of mecA in strain K8 and the second copy of mecA (mecA2) in strain K3 had mecA DNA sequences identical to that of S. aureus mecA, and the mecA region in these two strains was also similar to that of the same region in the S. aureus strain used for comparison. Interestingly, an open reading frame defining an N-terminal truncated polypeptide, NTORF101, with a high degree of homology to a DNA segment in the hypervariable region of methicillin-resistant S. aureus (and also similar to the Escherichia coli gene ugpQ) was also identified downstream of the mecA homolog of strain K11, representing S. sciuri subsp. carnaticum. The ugpQ-like gene is not present in methicillin-susceptible strains of S. aureus. The presence of such a ugpQ-like gene together with the homolog of mecA in strain K11 supports the speculation that these genetic elements may be evolutionary relatives and/or precursors of the genetic determinant of methicillin resistance in S. aureus.
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Affiliation(s)
- S Wu
- Laboratory of Microbiology, The Rockefeller University, New York, New York 10021, USA
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38
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Hiramatsu K. Vancomycin resistance in staphylococci. Drug Resist Updat 1998; 1:135-50. [PMID: 16904400 DOI: 10.1016/s1368-7646(98)80029-0] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/1997] [Revised: 02/24/1998] [Accepted: 02/28/1998] [Indexed: 10/25/2022]
Abstract
Recent emergence of vancomycin resistance in methicillin-resistant Staphylococcus aureus (VRSA) has posed a new threat to hospital infection control and antibiotic chemotherapy. Relatively low-level resistance of VRSA compared to that of vancomycin-resistant enterococci (VRE), and prevalence of S. aureus clinical strains heterogeneously resistant to vancomycin (hetero-VRSA), challenge the value of routine antibiotic susceptibility tests as a tool for the prediction of clinical efficacy of vancomycin therapy. This review summarizes the history of emergence of glycopeptide resistance in staphylococci and considers the mechanism of resistance in these organisms.
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Affiliation(s)
- K Hiramatsu
- Department of Bacteriology, Juntendo University, Tokyo, Japan.
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39
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Leelaporn A, Firth N, Paulsen IT, Skurray RA. IS257-mediated cointegration in the evolution of a family of staphylococcal trimethoprim resistance plasmids. J Bacteriol 1996; 178:6070-3. [PMID: 8830710 PMCID: PMC178470 DOI: 10.1128/jb.178.20.6070-6073.1996] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Analyses of the Staphylococcus epidermidis multiresistance plasmids pSK697 and pSK818 have revealed them to be closely related to the trimethoprim resistance plasmid pSK639, also isolated from S. epidermidis. pSK697 and pSK818 were found to contain a cointegrated copy of a second plasmid related to the S. epidermidis multidrug antiseptic and disinfectant resistance plasmid pSK108 and the S. aureus tetracycline resistance plasmid pT181, respectively. In contrast to pSK639, both plasmids were found to contain a third copy of IS257, such that the integrated plasmids in both cases are flanked by a copy of this element. This organization and the presence of duplicated sequences at the extremities of the integrated plasmids implicate IS257 in the formation of these cointegrate plasmids. Sequence analysis of the IS257 elements from these plasmids has provided insights into the probable mechanism of cointegration, viz., nonresolved replicative transposition of IS257.
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Affiliation(s)
- A Leelaporn
- School of Biological Sciences, University of Sydney, New South Wales, Australia
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40
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Lu Z, Li Y, Zhang Y, Kutish GF, Rock DL, Van Etten JL. Analysis of 45 kb of DNA located at the left end of the chlorella virus PBCV-1 genome. Virology 1995; 206:339-52. [PMID: 7831789 DOI: 10.1016/s0042-6822(95)80049-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Forty-five kilobases of DNA, including the previously sequenced 2.2-kb inverted repeat region, located at the left termini of the 330-kb Chlorella virus PBCV-1 genome were sequenced and analyzed. Eighty-five complete open reading frames (ORFs) larger than 195 nucleotides were identified. Thirty-seven of the 85 ORFs, which are densely packed on both strands of the DNA, were considered major ORFs. Fifteen of the major ORFs have similarity to genes in the databases, including bacterial glycerophosphoryl diester phosphodiesterase, bacteriophage T4 endonuclease V, D-isomer specific 2-hydroxyacid dehydrogenases, and beta-alanine synthetase and bacterial nitrilases. Two major ORFs resemble the virus major capsid protein. Three major ORFs contain three or more ankyrin-like repeat elements and four ORFs encode proline-rich proteins.
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Affiliation(s)
- Z Lu
- Plum Island Animal Disease Center, ARS, USDA, NAA, Greenport, New York 11944-0848
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41
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Archer GL, Niemeyer DM. Origin and evolution of DNA associated with resistance to methicillin in staphylococci. Trends Microbiol 1994; 2:343-7. [PMID: 7850198 DOI: 10.1016/0966-842x(94)90608-4] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The gene mediating resistance to methicillin in staphylococci (mecA) and its flanking sequences (mec DNA) make up a chromosomal DNA locus that is unique to methicillin-resistant bacteria; no equivalent locus exists in methicillin-susceptible cells. The origin of mec DNA is not known, but evidence supports horizontal transfer of mec DNA between different staphylococcal species and of the mecA gene between different Gram-positive genera.
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Affiliation(s)
- G L Archer
- Dept of Medicine, Virginia Commonwealth University, Medical College of Virginia, Richmond 23298-0049
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42
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Ryffel C, Strässle A, Kayser FH, Berger-Bächi B. Mechanisms of heteroresistance in methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 1994; 38:724-8. [PMID: 8031036 PMCID: PMC284532 DOI: 10.1128/aac.38.4.724] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Characteristic for methicillin-resistant (Mcr) staphylococci is the heterogeneous expression of the intrinsic methicillin resistance. The majority of the cells express resistance to low concentrations of methicillin, and a minority of the cells express resistance to much higher concentrations. We show here (i) that the presence of the mecA encoding region on plasmid pBBB79 was sufficient to render a methicillin-susceptible (Mcs) Staphylococcus aureus strain heteroresistant and (ii) that this Mcr strain segregated highly resistant subclones which retained the high-resistance phenotype under nonselective growth conditions. The Mcr strain with only mecA on plasmid pBBB79 thus behaved identically to a Mcr strain carrying the complete mec determinant integrated at its proper chromosomal site. (iii) Curing a such highly resistant subclone from plasmid pBBB79 yielded an Mcs strain that was as susceptible as the original Mcs parent strain. (iv) Comparisons were made between the original parent and the cured Mcs strain by backcrossing pBBB79 into them and looking at their progeny. Transductants derived from the formerly highly resistant cured strain became resistant to high concentrations of methicillin, whereas transductants derived from the original parent strain were resistant to lower concentrations of methicillin and showed the typical heterogeneous resistance. We deduced therefrom that the high-level resistance expressed by the minority of the population of Mcr S. aureus was due to a chromosomal mutation(s) (chr*) involving neither mecA nor the additional 30 kb of mec-associated DNA. Moreover, we could show that this postulated mutation chr* was not linked to the femAB operon, which is known to affect methicillin resistance levels.
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Affiliation(s)
- C Ryffel
- Institute of Medical Microbiology, University of Zürich, Switzerland
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43
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Georgopapadakou NH. Penicillin-binding proteins and bacterial resistance to beta-lactams. Antimicrob Agents Chemother 1993; 37:2045-53. [PMID: 8257121 PMCID: PMC192226 DOI: 10.1128/aac.37.10.2045] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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44
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van Belkum A, Bax R, Peerbooms P, Goessens WH, van Leeuwen N, Quint WG. Comparison of phage typing and DNA fingerprinting by polymerase chain reaction for discrimination of methicillin-resistant Staphylococcus aureus strains. J Clin Microbiol 1993; 31:798-803. [PMID: 8463389 PMCID: PMC263566 DOI: 10.1128/jcm.31.4.798-803.1993] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A typing procedure for methicillin-resistant Staphylococcus aureus (MRSA) based on the polymerase chain reaction (PCR) amplification of both mecA sequences and variable DNA sequences as present in the prokaryotic genome has been developed. Two primers based on the sequences of DNA repeats as discovered in gram-negative members of the family Enterobacteriaceae allow detection of variable regions in the genome of a gram-positive bacterium such as S. aureus, as does a newly described arbitrary primer. This procedure, enabling the detection of 23 different genotypes in a collection of 48 MRSA isolates, was validated by comparisons with phage typing studies. It appeared that within the same group of isolates only 13 different phagovars could be identified. Combination of the results from both phage typing and genotyping allowed the discrimination of 34 of 48 isolates. However, depending on the primer-variable complexity of the PCR fingerprints, which could also be modulated by combination of PCR primers, clear homologies between the groups defined by either phage typing or fingerprinting were observed. An analysis of an MRSA outbreak in a geriatric institution showed a collection of genetically homogeneous isolates. In agreement with phage typing, PCR fingerprinting revealed the identical natures of the MRSA strains isolated from all patients.
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45
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New nucleotide sequence data on the EMBL File Server. Nucleic Acids Res 1992; 20:935-58. [PMID: 1542609 PMCID: PMC312073 DOI: 10.1093/nar/20.4.935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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46
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Ryffel C, Kayser FH, Berger-Bächi B. Correlation between regulation of mecA transcription and expression of methicillin resistance in staphylococci. Antimicrob Agents Chemother 1992; 36:25-31. [PMID: 1375449 PMCID: PMC189220 DOI: 10.1128/aac.36.1.25] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Total RNA was used to study the effect of penicillinase plasmid pI524 and of mecR, the regulatory region located on the methicillin resistance determinant (mec), on the expression of mecA, the gene coding for the low-affinity penicillin-binding protein PBP2', in methicillin-resistant staphylococci. In the present report, we show that the regulation of methicillin resistance occurs primarily at the level of mecA transcription and that in the presence of intact plasmid pI524 or mecR, the gene undergoes negative control. The relative amount of mecA mRNA present during exponential growth in uninduced cultures matches the type of mecA regulation and decreases in the following order: constitutive greater than pI524 greater than mecR-dependent mecA expression. Induction of mecA by methicillin is faster in pI524- than in mecR-controlled strains. The overall mRNA half-life is similar for all strains analyzed. Our results indicate that methicillin resistance under mecR control in certain staphylococcal strains could escape detection by the standard disk diffusion test and broth microdilution test because of the very slow derepression of the mecA gene. This finding is of importance for the clinical detection of this type of methicillin resistance.
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Affiliation(s)
- C Ryffel
- Institute of Medical Microbiology, University of Zürich, Switzerland
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