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ABSTRACT: BACKGROUND: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in Thailand occur most frequently in healthcare facilities. However, reports of community-associated MRSA are limited. We characterized 14 MRSA isolates from outpatients (O-1 to O-14) by phenotypic and genotypic methods and compared them with 5 isolates from inpatients (I-1 to I-5). Thai MRSA isolates from a healthcare worker (N-1) and a pig (P-1) were also included as ST9 MRSA strains from other sources. RESULTS: All MRSA isolates from the outpatients and inpatients were multidrug-resistant (resistant to >=3 classes of antimicrobials). All of them except strains O-2 and I-3 carried type III SCCmec and belonged to agrI, coagulase IV, spa type t037 or t233, which related to ST239. The strain O-2 (JCSC6690) carried type IX SCCmec and belonged to agrII, coagulaseXIc, spa type t337 and ST9, whereas the strain I-3 carried a type III SCCmec and belonged to ST1429. Nucleotide sequence determination revealed that the type IX SCCmec element in strain O-2 was distinct from that in a Thai ST398 strain (JCSC6943) previously identified in 2011; nucleotide identities of ccrA and ccrB were 93 and 91%, respectively and several open reading frames (ORFs) at the joining regions were different. PCR experiments suggested that strain O-2 and N-1 carried similar SCCmec element, whereas that of strain P-1 was different, suggesting that distinct ST9-MRSA--IX clones might be spreading in this province. CONCLUSIONS: The SCCmecIX-ST9 MRSA clones of distinct SCCmec subtypes might have emerged in the Thai community and might also have disseminated into the hospital.
BMC Infectious Diseases 05/2013; 13(1):214. · 3.12 Impact Factor
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ABSTRACT: BD GeneOhm™ MRSA assay could identify MRSA strains at high ratio (97.8%). Analysis of 11 assay-negative MRSA strains suggested that insertion of non-mec SCC at the downstream of orfX, and carriage of SCCmec elements with left extremity that cannot be detected by the kit, might lead them being given improper negative status.
Antimicrobial Agents and Chemotherapy 04/2013; · 4.84 Impact Factor
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Chikara Kaito,
Yuki Saito,
Mariko Ikuo,
Yosuke Omae,
Han Mao,
Gentaro Nagano,
Tomoko Fujiyuki,
Shunsuke Numata,
Xiao Han,
Kazuaki Obata,
Setsuo Hasegawa,
Hiroki Yamaguchi,
Koiti Inokuchi, Teruyo Ito,
Keiichi Hiramatsu,
Kazuhisa Sekimizu
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ABSTRACT: Community acquired-methicillin resistant Staphylococcus aureus (CA-MRSA) is a socially problematic pathogen that infects healthy individuals, causing severe disease. CA-MRSA is more virulent than hospital associated-MRSA (HA-MRSA). The underlying mechanism for the high virulence of CA-MRSA is not known. The transcription product of the psm-mec gene, located in the mobile genetic element SCCmec of HA-MRSA, but not CA-MRSA, suppresses the expression of phenol-soluble modulin α (PSMα), a cytolytic toxin of S. aureus. Here we report that psm-mec RNA inhibits translation of the agrA gene encoding a positive transcription factor for the PSMα gene via specific binding to agrA mRNA. Furthermore, 25% of 325 clinical MRSA isolates had a mutation in the psm-mec promoter that attenuated transcription, and 9% of the strains had no psm-mec. In most of these psm-mec-mutated or psm-mec-deleted HA-MRSAs, PSMα expression was increased compared with strains carrying intact psm-mec, and some mutated strains produced high amounts of PSMα comparable with that of CA-MRSA. Deletion of psm-mec from HA-MRSA strains carrying intact psm-mec increased the expression of AgrA protein and PSMα, and virulence in mice. Thus, psm-mec RNA suppresses MRSA virulence via inhibition of agrA translation and the absence of psm-mec function in CA-MRSA causes its high virulence property.
PLoS Pathogens 04/2013; 9(4):e1003269. · 9.13 Impact Factor
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ABSTRACT: BACKGROUND: The spread of MRSA strains at hospitals as well as in the community are of great concern worldwide. We characterized the MRSA clones isolated at Tunisian hospitals and in the community by comparing them to those isolated in other countries. RESULTS: We characterized 69 MRSA strains isolated from two Tunisian university hospitals between the years 2004-2008. Twenty-two of 28 (79%) community-associated MRSA (CA-MRSA) strains and 21 of 41 (51%) healthcare-associated MRSA (HA-MRSA) strains were PVL-positive. The PVL-positive strains belonged to predicted founder group (FG) 80 in MLST and carried either type IVc SCCmec or nontypeable SCCmec that harbours the class B mec gene complex. In contrast, very diverse clones were identified in PVL-negative strains: three FGs (5, 15, and 22) for HA-MRSA strains and four FGs (5, 15, 45, and 80) for CA-MRSA strains; and these strains carried the SCCmec element of either type I, III, IVc or was nontypeable. The nucleotide sequencing of phi7401PVL lysogenized in a CA-MRSA strain JCSC7401, revealed that the phage was highly homologous to phiSA2mw, with nucleotide identities of more than 95%. Furthermore, all PVL positive strains were found to carry the same PVL phage, since these strains were positive in two PCR studies, identifying gene linkage between lukS and mtp (major tail protein) and the lysogeny region, both of which are in common with phi7401PVL and phiSa2mw. CONCLUSIONS: Our experiments suggest that FG80 S. aureus strains have changed to be more virulent by acquiring phi7401PVL, and to be resistant to beta-lactams by acquiring SCCmec elements. These novel clones might have disseminated in the Tunisian community as well as at the Tunisian hospitals by taking over existing MRSA clones.
BMC Microbiology 01/2013; 13(1):2. · 3.04 Impact Factor
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Teruyo Ito,
Keiichi Hiramatsu,
Alexander Tomasz,
Hermínia de Lencastre,
Vincent Perreten,
Matthew T G Holden,
David C Coleman,
Richard Goering,
Philip M Giffard,
Robert L Skov, [......],
Frederic Laurent,
Angela M Kearns,
Barry Kreiswirth,
Kwan Soo Ko,
Hajo Grundmann,
Johanna E Sollid,
Joseph F John,
Robert Daum,
Bo Soderquist,
Girbe Buist
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ABSTRACT: Methicillin-resistant staphylococci are disseminated all over the world and are frequent causes of healthcare- and community-associated infections.…
Antimicrobial Agents and Chemotherapy 08/2012; 56(10):4997-4999. · 4.84 Impact Factor
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Jun Yamakawa,
Mayumi Aminaka,
Katsuko Okuzumi,
Hiroyoshi Kobayashi,
Yuki Katayama,
Shigemi Kondo,
Ayako Nakamura,
Toyoko Oguri,
Satoshi Hori,
Longzhu Cui, Teruyo Ito,
Jingxun Jin,
Hisashi Kurosawa,
Kazuo Kaneko,
Keiichi Hiramatsu
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ABSTRACT: Vancomycin-intermediate Staphylococcus aureus (VISA) and its precursor, heterogeneous VISA (hVISA), are increasingly the cause of vancomycin treatment failure. Prolonged glycopeptide treatment causes the emergence of these pathogens. However, we recently reported that hVISA can be generated by methicillin-resistant S. aureus (MRSA) exposure to imipenem (Katayama et al., Antimicrob Agents Chemother. 53:3190-6). We report here a retrospective prevalence study of VISA and hVISA on 750 MRSA clinical strains isolated from 31 Japanese national university hospitals in 1990, the year before the introduction of injectable vancomycin into clinical use in Japan in 1991. No VISA strain was identified, but population analysis identified 38 hVISA strains (5.1%) from 19 hospitals. We also determined the nucleotide sequences of vraSR, walRK, clpP, and rpoB genes whose mutations are known to be associated with vancomycin resistance. When compared with vancomycin-susceptible MRSA strain N315, six of the 38 hVISA strains possessed nonsynonymous mutations in vraSR, seven in walRK, and two in rpoB genes, Thirteen of 38 (34.2%) hVISA strains possessed at least one of these mutations. Results were consistent with our hypothesis that hVISA was present in Japanese hospitals before the clinical introduction of vancomycin.
Journal of Infection and Chemotherapy 10/2011; 18(3):406-9. · 1.80 Impact Factor
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ABSTRACT: The genes lukS-PV and lukF-PV for Panton-Valentine leukocidin (PVL) that confers high virulence to Staphylococcus aureus are located on the prophages (PVL phages) which have been classified into group 1 and 2 sfi21-like Siphoviridae. We report novel PVL phages lysogenized in ST59 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in Japan (JCSC7247) and Taiwan (JCSC5967). The genomes of φ7247PVL and φ5967PVL showed more than 99% identity, and the regions containing the five genes located at both ends of the prophages, int (integrase), hol (holin), ami (amidase), lukS-PV, and lukF-PV, are highly homologous to extant PVL phages. The genes for the structural module are less homologous to these phages, but are highly homologous to non-PVL phages belonging to group 3 Sfi21-like Siphoviridae, for example φN315. Subsequent PCR identification and nucleotide sequencing of an additional 11 Taiwanese ST59 MRSA isolates suggested they all carry the same phage as φ5967PVL, which differed from φ7247PVL by a single base. This study adds evidence to the notion that novel PVL phages would be generated through illegitimate recombination events by acquiring the region at which hol, ami, luk, and int genes would line up upon lytic growth, and suggests that the PVL-positive MRSA clones that have emerged worldwide may carry distinct phages.
FEMS Microbiology Letters 07/2011; 323(1):20-8. · 2.04 Impact Factor
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Masaaki Higashiyama, Teruyo Ito,
Xiao Han,
Junichiro Nishiyama,
Akemi Tanno,
Toshiko Wada,
Youichi Funaoka,
Yusuke Yoshida,
Kei Mikita,
Tomomichi Ogawa,
Yasushi Okusa,
Koki Kaku,
Junichi Hatada,
Keiichi Hiramatsu,
Akihiko Kawana
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ABSTRACT: Our retrospective investigation of methicillin-resistant Staphylococcus aureus (MRSA) infection at a hospital in Japan around 2007 suggested dissemination of community-associated MRSA (CA-MRSA) strains among healthy students in a Japanese boarding school, which frequently caused skin disease and exhibited the same antibiogram patterns.
Active surveillance of skin diseases for 6 months after May 2008, examination of MRSA carriage in selected high-risk groups, and investigation of their life circumstances, including environmental cultures, were conducted in the school. Furthermore, we strengthened hygiene practices and improved recognized risk factors from November 2008 and observed the occurrence of skin diseases and MRSA carriage rate for the evaluation of infection controls.
We identified 21 patients with skin diseases in whom MRSA strains were isolated. MRSA colonization rates in 3 selected groups ranged from 7.6% to 36.6%. The rates of both skin disease and MRSA carriage decreased significantly after infection controls were introduced. Genetic analysis revealed a main dissemination of a PVL-positive SCCmec IVc clone (41/47 isolates in total), presenting as a different pulsed-field type than USA300.
This first report of a PVL-positive CA-MRSA outbreak in Japan demonstrates systematic management of dissemination by conducting surveillance in a closed community.
American journal of infection control 06/2011; 39(10):858-65. · 3.01 Impact Factor
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ABSTRACT: The structures of staphylococcal cassette chromosome mec (SCCmec) elements carried by 31 clonal complex 398 (CC398) methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from the participants at a conference were analyzed. The SCCmecs were classified into novel types, namely, IX, X, V(5C2&5) subtype c, and IVa. Type V(5C2&5) subtype c, IX, and X SCCmecs carried genes conferring resistance to metals. The structures of SCCmecs from CC398 strains were distinct from those normally found in humans, adding to the evidence that humans are not the original host for CC398.
Antimicrobial Agents and Chemotherapy 03/2011; 55(6):3046-50. · 4.84 Impact Factor
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ABSTRACT: The proportion of MRSA strains that cause skin and soft infections has recently increased. In 3 months we have characterized 17 MRSA strains isolated from children with impetigo at a Japanese hospital. Seventeen MRSA strains belonged to 7 clones defined by clonal complex (CC) in MLST genotype and type of SCCmec, which were rarely identified among healthcare-associated MRSA: CC 91-SCCmecIIb (4 strains); CC91-SCCmecIIn (2 strains); CC91-SCCmecIVa (2 strains); CC91-SCCmecV (4 strains); CC88-SCCmecIVg (3 strains); CC1-SCCmecIVc (1 strain); and CC5-SCCmecIVn (1 strain). Although one strain belonged to CC5, which has been commonly identified in healthcare-associated MRSA, it did not carry type II SCCmec, but carried type IV SCCmec. Fourteen of the 17 strains carried exfoliative toxin a or b gene, and none carried Panton-Valentine leukocidine gene. Furthermore, we determined the entire nucleotide sequences of two type V SCCmec elements carried by strains JCSC5952, a CC91 strain, and TSGH17, a Taiwanese CC59 strain. The structure of SCCmecJCSC5952 was more than 99% homologous in nucleotide identity with those of Taiwanese PVL-positive ST59 MRSA strains TSGH17 and PM1, which were designated as type V (5C2&5). Identification of multiple MRSA clones distinct from those disseminating at the hospital suggests that MRSA strains might be emerging in the community from MSSA strains by acquiring SCCmec elements on various occasions. Carriage of the similar type V(5C2&5) SCCmec element by strains of distinct genetic backgrounds, CC91 and CC59, suggested horizontal transfer of the SCCmec element.
Journal of Infection and Chemotherapy 02/2011; 17(5):609-21. · 1.80 Impact Factor
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Chikara Kaito,
Yuki Saito,
Gentaro Nagano,
Mariko Ikuo,
Yosuke Omae,
Yuichi Hanada,
Xiao Han,
Kyoko Kuwahara-Arai,
Tomomi Hishinuma,
Tadashi Baba, Teruyo Ito,
Keiichi Hiramatsu,
Kazuhisa Sekimizu
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ABSTRACT: The F region downstream of the mecI gene in the SCCmec element in hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) contains two bidirectionally overlapping open reading frames (ORFs), the fudoh ORF and the psm-mec ORF. The psm-mec ORF encodes a cytolysin, phenol-soluble modulin (PSM)-mec. Transformation of the F region into the Newman strain, which is a methicillin-sensitive S. aureus (MSSA) strain, or into the MW2 (USA400) and FRP3757 (USA300) strains, which are community-acquired MRSA (CA-MRSA) strains that lack the F region, attenuated their virulence in a mouse systemic infection model. Introducing the F region to these strains suppressed colony-spreading activity and PSMα production, and promoted biofilm formation. By producing mutations into the psm-mec ORF, we revealed that (i) both the transcription and translation products of the psm-mec ORF suppressed colony-spreading activity and promoted biofilm formation; and (ii) the transcription product of the psm-mec ORF, but not its translation product, decreased PSMα production. These findings suggest that both the psm-mec transcript, acting as a regulatory RNA, and the PSM-mec protein encoded by the gene on the mobile genetic element SCCmec regulate the virulence of Staphylococcus aureus.
PLoS Pathogens 01/2011; 7(2):e1001267. · 9.13 Impact Factor
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Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 09/2010; 84(5 Suppl 1):23-33.
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Nippon rinsho. Japanese journal of clinical medicine 08/2010; 68 Suppl 8:560-7.
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ABSTRACT: Methicillin-resistant Staphylococcus aureus (MRSA) has spread worldwide. It is a major cause of hospital-acquired infections in most hospitals for nearly half century. The present study was conducted to examine the antimicrobial susceptibilities and staphylococcal cassette chromosome mec (SCCmec)-type for MRSA isolates from 237 patients treated at Srinagarind Hospital between September 2002 and August 2003. Antimicrobial susceptibility testing for all isolates was performed using an agar dilution method and SCCmec-types of 81 representatives from 237 isolates were determined using multiplex PCR. The minimum inhibitory concentration (MIC) ranges for the MRSA isolates were as follows: cefazolin 8 to > or =64; erythromycin < or = 0.5 to > or =64; gentamicin < or = 0.5 to > or =64; imipenem < or = 0.5 to >16; ofloxacin < or = 0.5 to > or =64; oxacillin 16 to > or =64; tetracycline 2 to > or =64 and vancomycin < or = 0.5 to 2 microg/ml. All MRSA isolates were susceptible to vancomycin, but only 0.4% to 8.9% was susceptible to the remaining antimicrobial agents. Of the 81 isolates tested, 2 types of SCCmec were found (76 with type III and 2 with type II) and no mecA gene was detected in 3 isolates. Sixty-seven of the 78 isolates carried the mercury-resistant operon. The multilocus sequence type in isolates with type III SCCmec was ST239 and in isolates with type II SCCmec was ST5.
The Southeast Asian journal of tropical medicine and public health 07/2010; 41(4):920-7. · 0.60 Impact Factor
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Masaaki Higashiyama, Teruyo Ito,
Xiao Han,
Kenichiro Ono,
Kenzo Minamimura,
Fumihiro Sakakibara,
Akemi Tanno,
Junichiro Nishiyama,
Junichi Hatada,
Keiichi Hiramatsu,
Akihiko Kawana
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ABSTRACT: We report a case of epidural abscess caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain USA300 in a previously healthy 25-year-old American woman who lived in Japan for more than 1 year. She started to complain of severe headache that continued for about 10 days after improvement of subcutaneous abscesses caused by MRSA. Computed tomography (CT) and magnetic resonance imaging (MRI) showed epidural abscess. As epidural abscess was not improved by treatment with vancomycin and ceftriaxone, craniotomy and drainage were performed, and the severe headache disappeared. Characteristics of the MRSA strain isolated from the abscess were identical to those of strain USA300; multilocus sequence typing sequence type 8, staphylococcal cassette chromosome mec type IVa, Panton-Valentine leukocidin positive, arginine catabolic mobile element positive, and pulsed-field gel electrophoresis type USA300. This may be the first report of epidural abscess caused by USA300 strain in Japan. Because CA-MRSA strains, including USA300, have begun to spread in Japan, epidural abscess should be taken into account in the diagnosis of previously healthy patients with persistent headache accompanied by skin lesions.
Journal of Infection and Chemotherapy 04/2010; 16(5):345-9. · 1.80 Impact Factor
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ABSTRACT: We previously suggested that gut bacteria may be involved in the onset of Kawasaki disease (KD). In this study, we evaluated the production of heat shock proteins (hsps) and superantigens (sAgs) by microorganisms isolated from the jejunal mucosa of 19 children with KD in the acute phase and from 15 age-matched control children. We identified 13 strains of Gram-negative microbes from patients with KD; these microbes produced large amounts of hsp60 and induced pro-inflammatory cytokine production by peripheral blood mononuclear cells. The Gram-negative microbes also elicited endogenous hsp60 production, leading to the secretion of anti-inflammatory intereukin-10 (IL-10). We also identified 18 strains of Gram-positive cocci that had superantigenic properties and which induced the expansion of Vbeta2 T cells in vitro. All bacteria identified in this study were antibiotic resistant. These data suggest that sAg and hsps produced by gut bacteria might be involved in KD.
Immunology 12/2009; 128(4):511-20. · 3.32 Impact Factor
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ABSTRACT: Panton-Valentine leukocidin (PVL) has long been considered a critical toxin in severe Staphylococcus aureus infection. PVL presumably breaches the body's defense system by lysing human polymorphonuclear cells (PMNs). Recently, however, bioactive peptides--phenol-soluble modulins (PSMs)--have been proposed as the main player in the lysis of PMNs, rather than PVL. This study aimed to resolve uncertainty concerning the cause of the lysis of human PMNs by using recombinant PVL toxins and PVL-neutralizing monoclonal antibodies. The recombinant PVL toxins showed strong lytic activity against human but not murine neutrophils. Moreover, the lytic activity of culture supernatants of strains USA400 MW2 and USA300 FPR3757 were completely neutralized by anti-PVL monoclonal antibodies. In contrast, phenol-soluble modulin alpha 3--the most potent PSM peptide--failed to lyse human PMNs at the concentrations contained in the culture supernatants. Phenol-soluble modulin alpha 3 did, however, enhance PVL-mediated lysis of human PMNs.
The Journal of Infectious Diseases 10/2009; 200(5):715-23. · 6.41 Impact Factor
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ABSTRACT: Recently, strains of methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin (VCM) have been clinically isolated. The antibacterial activity of a new drug, linezolid (LZD), in such a strain was evaluated by measuring bacterial metabolic activity. A total of 73 MRSA strains having various susceptibilities to VCM were subjected to a novel and highly sensitive chemiluminescence-based assay. LZD MIC in the tested strains, measured by the microbroth dilution method, was within the range 1-4 mg/l (mostly </=2 mg/l), except for one LZD-resistant strain (NRS127; MIC=7 mg/l), and showed no correlation with VCM resistance. The chemiluminescence assay demonstrated that bacterial metabolic activity was strongly suppressed with increasing LZD concentration. The chemiluminescence intensity curve had a low baseline activity without tailing in most strains. The present results suggest that LZD has strong antibacterial activity against MRSA strain, and would be effective for treatment of infections that are poorly responsive to VCM. The chemiluminescence assay facilitated sensitive and discriminative susceptibility testing within a relatively short time.
Journal of Microbiology and Biotechnology 07/2009; 19(7):734-42. · 1.38 Impact Factor
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ABSTRACT: We identified two novel staphylococcal cassette chromosome mec (SCCmec) elements in sequence type 8 methicillin-resistant Staphylococcus aureus strains isolated in Japan: type II.5 SCCmec, whose J1 region was highly homologous to that of type I.2 SCCmec of strain PL72 (previously isolated in Poland), and its J1 region variant caused by the deletion/insertion of putative conjugative transposon Tn6012, identified in four S. aureus genomes.
Antimicrobial Agents and Chemotherapy 05/2009; 53(6):2616-9. · 4.84 Impact Factor
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ABSTRACT: We screened 533 and 361 methicillin (meticillin)-resistant Staphylococcus aureus strains isolated in a university hospital in 2002 and 2003 and in 2006 and 2007, respectively, and identified 4 (0.8%) of the strains in the first group and 8 (2.2%) of the strains in second group as heterogeneous vancomycin-resistant S. aureus (heterogeneous VISA) strains and 3 (0.8%) of the strains in the second group as VISA strains. This is the first report of VISA strains isolated from patients in Thailand.
Journal of clinical microbiology 05/2009; 47(7):2311-6. · 4.16 Impact Factor
