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A 15-year-old boy, who had had a furuncle on his femur, developed femoral pyomyositis and osteomyelitis complicated by septic pulmonary embolism. Panton-Valentine leukocidin-positive (PVL(+)) ST59 methicillin-susceptible Staphylococcus aureus (MSSA) was isolated from pus and blood. Chemotherapy was started with cefazolin, followed by combination therapy with meropenem/vancomycin with surgery. The MSSA (strain KS1) was positive for increased levels of cytolytic peptide (psmα and hld) and staphylococcal enterotoxin B (SEB), and manifested IS1216V-mediated multidrug resistance (to erythromycin, clindamycin, kanamycin, streptomycin, and chloramphenicol), similar to a genome-analyzed reference strain (PM1) of ST59/SCCmecV(5C2&5) community-associated methicillin-resistant S. aureus (Taiwan CA-MRSA), but unlike another reference strain (M013) of Taiwan CA-MRSA in terms of resistance. The data suggest that CA-MSSA KS1, characterized by PVL, increased levels of cytolytic peptide, SEB, and multidrug resistance, is a possible ancestral strain of Taiwan CA-MRSA and causes the unique association of osteomyelitis and septic pulmonary embolism, requiring complicated management., (Copyright © 2014. Published by Elsevier B.V.)

Methicillin-resistant Staphylococcus aureus (MRSA) is a common multidrug-resistant (MDR) pathogen. We herein discussed MRSA and its infections in Krasnoyarsk, Siberian Russia between 2007 and 2011. The incidence of MRSA in 3,662 subjects was 22.0% and 2.9% for healthcare- and community-associated MRSA (HA- and CA-MRSA), respectively. The 15-day mortality rates for MRSA hospital- and community-acquired pneumonia (HAP and CAP) were 6.5% and 50%, respectively. MRSA CAP cases included pediatric deaths; of the MRSA pneumonia episodes available, ≥27.3% were associated with bacteremia. Most cases of HA-MRSA examined exhibited ST239/spa3(t037)/SCCmecIII.1.1.2 (designated as ST239Kras), while all CA-MRSA cases examined were ST8/spa1(t008)/SCCmecIV.3.1.1(IVc) (designated as ST8Kras). ST239Kras and ST8Kras strongly expressed cytolytic peptide (phenol-soluble modulin α, PSMα; and δ-hemolysin, Hld) genes, similar to CA-MRSA. ST239Kras pneumonia may have been attributed to a unique set of multiple virulence factors (MVFs): toxic shock syndrome toxin-1 (TSST-1), elevated PSMα/Hld expression, α-hemolysin, the staphylococcal enterotoxin SEK/SEQ, the immune evasion factor SCIN/SAK, and collagen adhesin. Regarding ST8Kras, SEA was included in MVFs, some of which were common to ST239Kras. The ST239Kras (strain OC3) genome contained: a completely unique phage, φSa7-like (W), with no att repetition; S. aureus pathogenicity island SaPI2R, the first TSST-1 gene-positive (tst+) SaPI in the ST239 lineage; and a super copy of IS256 (≥22 copies/genome). ST239Kras carried the Brazilian SCCmecIII.1.1.2 and United Kingdom-type tst. ST239Kras and ST8Kras were MDR, with the same levofloxacin resistance mutations; small, but transmissible chloramphenicol resistance plasmids spread widely enough to not be ignored. These results suggest that novel MDR and MVF+ HA- and CA-MRSA (ST239Kras and ST8Kras) emerged in Siberian Russia (Krasnoyarsk) associated with fatal pneumonia, and also with ST239Kras, a new (Siberian Russian) clade of the ST239 lineage, which was created through stepwise evolution during its potential transmission route of Brazil-Europe-Russia/Krasnoyarsk, thereby selective advantages from unique MVFs and the MDR.

Iliopsoas abscesses (IPAs) from methicillin-resistant Staphylococcus aureus (MRSA) are rare; however, IPAs from community-associated MRSA (CA-MRSA) may be increasing. In Japan, we previously described an adolescent athlete case of Panton-Valentine leukocidin (PVL)-positive ST30 CA-MRSA (strain NN12). In this study, we describe an IPA and discitis case from a variant of the successful PVL-negative CA-MRSA clone (ST8 CA-MRSA/J) in Japan. The patient was a 62-year-old man with intractable eczema, who had been diagnosed with IPAs and discitis (L1-L2). CA-MRSA (strain NN55) was isolated from blood, pus, and joint fluid. The invasive infections seemed to have originated in his intractable eczema, and the characteristics of this case, systemic myalgia and marked thrombocytopenia, seemed to have been caused by an exotoxin. Molecular genetic analysis revealed that NN55 possessed genotype ST8/spa606(t1767)/agr1/CoaIII and SCCmecIV of a novel subtype (encoding new cell-wall-anchored surface protein/J [CWASP/J]), exhibited enhanced expression of the cytolytic peptide genes, psmα and hld, and was resistant to gentamicin (caused by aacA-aphD), similar to ST8 CA-MRSA/J; however, NN55 lacked pathogenicity island SaPIj50 [carrying tst, encoding toxic shock syndrome toxin-1 (TSST-1)] of ST8 CA-MRSA/J, suggesting a variant (ST8 CA-MRSA/Jv). Strains NN12 and NN55 both caused bacteremia, IPAs, and adjacent musculoskeletal infections, preceded by intractable skin infections, and possessed high potential for adherence and enhanced expression of psmα and hld. The data suggest the role of a combination of CA-MRSA adhesin/cytolytic peptides (not PVL or TSST-1) in the pathogenesis of IPAs (and perhaps of systemic myalgia and marked thrombocytopenia).

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), which often produces Panton-Valentine leukocidin (PVL), is an emerging threat in the community. In Japan, for example, PVL-positive ST8 CA-MRSA (USA 300), which originated from the United States, persisted in families for a year and caused severe invasive infection in a child. In this study, we describe a long-term familial infection cluster caused by novel PVL-positive CA-MRSA, which most probably originated from India. This MRSA persisted in related families for more than 2 years with colonization of, for example, the nares and cheek. At least 6 of 12 members (50%) developed deep cutaneous abscesses, including recurrent and multifocal abscesses, every 1.2 months on average. All MRSA isolates from colonization and abscesses were the same, albeit with a variant in pulsed-field gel electrophoresis analysis. The MRSA exhibited the genotype ST22/spa113(t005)/SCCmecIVa/coagulase gene (coa) novel type and strong hemolysis activity. Moreover, the MRSA exhibited high biofilm formation (which was markedly enhanced by sub-MICs of oxacillin). Some patients were treated with levofloxacin, with successful MRSA eradication even from the whole body surface sites; however, short-term patient follow-up was not sufficient to demonstrate eradication of the familial infection cluster. The data suggest that PVL-positive novel ST22 CA-MRSA emerged in Japan, causing a long-term familial infection cluster, and that the success of ST22 CA-MRSA as both a colonizer and a pathogen could result from the combination of its strong biofilm formation and other virulence factors. A long-term patient (or carrier) follow-up is needed in the community.

Methicillin-resistant Staphylococcus aureus (MRSA) includes hospital-acquired MRSA (HAMRSA) and community-acquired MRSA (CA-MRSA). Panton-Valentine leukocidin (PVL)-positive multilocus sequence type 30 (ST30) MRSA is one of worldwide CA-MRSA, which has also persisted in Japan since the 1980s. However, unexpectedly, it was not the same ST30 clone throughout. Before 2000, it was HA-MRSA with spa43 and ψSa3sea (phage Sa3 carrying the sea gene) and only one PVL-positive MRSA in Japan; in the 1980s, ST30 MRSA accounted for 23.5% of HA-MRSA, showed multidrug resistance, had high MICs for oxacillin and imipenem, and caused decubitus and pneumonia in hospitalized patients. A dynamic clonal change (spa43/ψSa3sea→ spa19) occurred around 2000-2002. A rare spa43/ψSa3sea/SCCmecI-IE25923 genotype also emerged. After 2002, the prevalent spa19 clone was CA-MRSA; it accounted for only 0.3% (or less) of MRSA in hospitals but 7.6% of CA-MRSA. Since 2007, PVL-positive CA-MRSA with other ST types (such as ST8, ST22, and ST59) also emerged in Japan, albeit at a low frequency. ST30/spa19 CA-MRSA occasionally caused severe invasive infections and a novel ST1335/spa19 genotype emerged. These ST30/spa19 CA-MRSA and variants were identified by pulsed field gel electrophoresis. Further analysis revealed that PVL-positive ST30/spa19 CA-MRSA is a highlyvirulent, successful clone, having a potential of clonal expansion.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), which is often positive for Panton-Valentine leucocidin (PVL), is increasingly noted as an emerging pathogen worldwide. In Japan, PVL-positive CA-MRSA belonging to multilocus sequence type (ST) 30 has spread and caused, for example, pediatric death due to community-acquired pneumonia and severe pelvic abscesses in an athlete. In this study, we investigated a new rapid screening method for PVL-positive ST30 CA-MRSA and its related clone by a combination of multiplex polymerase chain reaction (M-PCR) and pulsed-field gel electrophoresis (PFGE). For M-PCR, the targets of the assay were the five genes for PVL, collagen adhesin, bone sialoprotein adhesin, methicillin resistance, and S. aureus-specific thermostable nuclease. Only PVL-positive ST30 CA-MRSA strains produced all five bands in M-PCR. With PFGE, Japanese strains and most foreign strains of PVL-positive ST30 CA-MRSA shared the same pattern. Moreover, PFGE distinguished current PVL-positive CA-MRSA ST30/spa19 strains from previous PVL-positive MRSA ST30/spa43 strains (which were isolated at the time of nosocomial MRSA outbreaks in the late 1980s and early 1990s) in Japan. Thus, the M-PCR assay rapidly, and the M-PCR/PFGE combination assay more precisely, discriminated between PVL-positive ST30 CA-MRSA (or its related clone) and PVL-positive CA-MRSA belonging to other ST types such as ST1, 8, 59, and 80, PVL-negative CA-MRSA, hospital-acquired MRSA, methicillin-susceptible S. aureus, or coagulase-negative staphylococci (CNS), including MRCNS. This screening method is more useful than genotyping for routine work in many clinical laboratories.

The major methicillin-resistant Staphylococcus aureus(MRSA) distributed among hospitals in Japan is New York/Japan clone [multilocus sequence type 5 (ST5), agr type 2 and methicillin resistance locus type (SCC mec) II] which possesses both the toxic shock syndrome toxin 1 gene (tst) and staphylococcal enterotoxin C gene (sec). In this study, we collected 245 MRSA strains from four hospitals during 2001 to 2005 in Niigata, Japan, and analyzed tst and sec genes and SCC mec type among them. A total of 13 strains were further examined for their genotypes, virulence gene patterns and drug resistance. Among the 245 strains four tst sec genes patterns were observed; tst(+) sec(+) strains represented a majority of 86.5% and 9.4% were tst(-) sec(-). SCCmec typing revealed that 91.4% had type II, 4.1% type IV and 4.1% type I. Multilocus sequence typing (MLST) revealed that 10 of the 13 typed strains belonged to clonal complex 5 (7 had ST5 while 3 were single locus variants of ST5) with similar characteristics to the New York/Japan clone and possessed multi-drug resistance with high virulence gene content. The remaining 3 strains were ST8 (n=2) and ST91 (n=1). The ST91 strain had SCC mec IV and seemed to originate in the community, while ST8 strains exhibited SCC mec type I, which is distinct from community type IV. The data suggest that MRSA in hospitals in Niigata now mainly includes the New York/Japan clone (undergoing genomic divergence and clonal expansion) and other minor types (e.g. ST8) as well as the community type.