Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus outbreak among healthcare workers in a long-term care facility.

BACKGROUND: We investigated an outbreak of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections that occurred among healthcare workers (HCWs) but not among residents of a long-term care facility (LTCF). METHODS: Cases of S. aureus infection were sought by reviewing the medical records of residents and HCWs. In order to identify risk factors for the development of an S. aureus infection, an unmatched case-control study was conducted. Cases were all HCWs with a clinically compatible S. aureus infection; controls were HCWs with no history of a clinically compatible S. aureus infection. Cases and controls were interviewed and anterior nasal swabs were collected. RESULTS: Over a period of 14 months, a total of eight cases were identified among practice nurses, giving an attack rate of 10% for this category of profession. All isolates were identified as MRSA Panton-Valentine leukocidin (PVL)-producing SCCmec type IV. By multivariate analysis, working in a specific zone and being a practice nurse were found to be statistically significant risk factors for infection. CONCLUSIONS: The current outbreak indicates that HCWs may serve as vehicles for the entry of PVL-positive MRSA strains from the community into LTCFs, and that deficient hygiene practices and unrecognized carriage may facilitate spread. Given the increasing prevalence of PVL-positive MRSA infections worldwide, guidelines for the eradication of PVL-positive MRSA carriage within closed communities should be established and efforts to obtain cultures from compatible infections should be made.

High rates of community-acquired, Panton-Valentine leukocidin (PVL)- positive methicillin-resistant S. aureus (MRSA) infections in adult outpatients in Greece.

Staphylococcus aureus was isolated in 88 (30.8%) of 286 adult patients suffering from various skin and soft-tissue infections examined in the outpatient department of a 650 bed tertiary-care hospital of Athens, Greece between January 2006 and December 2007. Twenty-seven (30.7%) of the S. aureus infections were caused by methicillin-resistant S. aureus (MRSA). All MRSA isolates were also resistant to tetracycline, fucidic acid and kanamycin, but were sensitive to gentamicin and tobramycin, as well as to to cotrimoxazole, chloramphenicol, quinolones, clindamycin and erythromycin. All isolates belonged to staphylococcal cassette chromosome mec elements (SCCmec) type IV, and were found to carry the lukF-PV and lukS genes coding for Panton-Valentine leukocidin (PVL). Pulsed-field gel electrophoresis (PFGE) and spa-typing revealed high genetic similarity among all MRSA isolates and with the PFGE pattern of the well-described ST80 clone that seems to be spreading through Europe. The high prevalence of MRSA among S. aureus infections in the community signify that empiric therapy in Greece, when clinically indicated, should exclude beta-lactam antibiotics. Moreover, the establishment of an active screening for PVL-positive community-acquired (CA)-MRSA carriage and the adoption of a search and destroy strategy for CA-MRSA in all patients admitted with purulent skin and soft-tissue is of high priority in Greece as well as in all European countries which face high rates of CA-MRSA infection.

Epidemiology of metalloenzyme-producing Pseudomonas aeruginosa in a tertiary hospital in Greece.

A total of 132 infections of Pseudomonas aeruginosa (including 112 imipenem resistant, 32 of them producing VIM-2 beta-lactamase) were identified during a one-year period (June 2002-June 2003). PFGE molecular typing revealed that P. aeruginosa clinical isolates sensitive to imipenem, P. aeruginosa isolates resistant to imipenem but VIM-negative, and P. aeruginosa-resistant and VIM-positive isolates could be allocated to three different clusters with approximately 70% similarity. A case control study of patients infected with an MBL-producing imipenem-resistant P. aeruginosa isolate and controls (patients hospitalized in the same time period with no infection), revealed that only the number of catheters present at the time of the infection was strongly associated with the development of infection due to VIM-producing P. aeruginosa (OR 4.83, 95% CI: 1.94-12.0). In conclusion, the results of the molecular typing combined with the results of the case control study indicate that in the specific hospital setting, infection control, addressed specifically to critically ill patients, is an important part of any strategy to reduce imipenem-resistant infections.

Clinical and molecular epidemiology of community-acquired, methicillin-resistant Staphylococcus aureus infections in children in central Greece.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in children have increased considerably in our area. In this study, we prospectively examined the epidemiological, clinical and molecular profile of CA-MRSA infections in children in central Greece. A total of 198 staphylococcal strains were isolated from patients with community-acquired infections over a 28-month period and 88 (44%) were found to be methicillin-resistant. Most patients with CA-MRSA had skin and soft-tissue infections (73%). Hospitalisation and surgery were more commonly required for patients with MRSA strains (p = 0.001 and p < 0.001, respectively). The presence of Panton-Valentine leukocidin (PVL) genes was identified in 28/41 (68%) CA-MRSA strains. All PVL(+) strains were found to carry a staphylococcal chromosomal cassette (SCC) mec element type IV and belonged to a single electrophoretic type similar to the European multi-locus sequence type 80 (ST80). The recent increase in CA-MRSA infections in children in our area is largely associated with the spread of the ST80 clone and their clinical characteristics are similar to those described in other parts of the world where different MRSA clones predominate.

Community-acquired pneumonia and bacteremia due to methicillin-resistant Staphylococcus aureus carrying Panton-Valentine-leukocidin gene in Greece: two case reports and literature review.

We report the first two cases of community-acquired necrotizing pneumonia and bacteremia complicated by acute respiratory distress syndrome (ARDS) due to Panton-Valantine leukocidin-producing methicillin-resistant Staphylococcus aureus (MRSA-PVL) in Greece, together with a short literature review. Diagnosis was made by culture and broad spectrum PCR of respiratory secretions and blood. One patient received appropriate therapy and recovered fully. The other one died rapidly due to septic shock and life-threatening hemoptysis. Clinicians should be suspicious of community-acquired pneumonia due to MRSA-PVL strain, because rigorous microbiological diagnosis, early and appropriate therapy is essential for favorable outcome.

Emergence of Proteus mirabilis carrying the bla metallo-beta-lactamase gene.

Seven genetically related Proteus mirabilis clinical isolates from a hospital in Thessaloniki, Greece, exhibited decreased susceptibility to imipenem and carried a bla(VIM-1) metallo-beta-lactamase gene. PCR mapping revealed that bla(VIM-1) was part of a class 1 integron that was probably located in the chromosome and also included the aacA7, dhfr and aadA genes. This is the first description of the bla(VIM-1) metallo-beta-lactamase gene in P. mirabilis.

Transferable DHA-1 cephalosporinase in Escherichia coli.

Three Escherichia coli isolates resistant to third-generation cephalosporins but negative for extended-spectrum beta-lactamase production were isolated from hospitalised patients in Zagreb, Croatia, during June 2003 to February 2004. Resistance was due to the inducible production of a DHA-1 cephalosporinase. Each isolate contained an integron-associated bla(DHA-1)-ampR sequence carried by similar-sized plasmids, of which one was self-transferable. Serotyping and polymerase chain reaction typing using ERIC2 primer indicated that the isolates were distinct. This is the first description of DHA beta-lactamase production in E. coli.

Community acquired MRSA infections in a paediatric population in Greece.

We investigated the characteristics of 20 community acquired methicillin resistant Staphylococcus aureus (MRSA) strains isolated in a paediatric hospital in Athens. Eighteen of these, all isolated from skin and soft tissue infections, carried the Panton-Valentine leukocidin (PVL) determinants. They all were found resistant to fusidic acid, tetracycline and kanamycin, and displayed a PFGE pattern identical to that of the well-described ST80 CA-MRSA clone circulating in various European countries.

Emergence of CTX-M-15-producing enterobacteria in Cameroon and characterization of a blaCTX-M-15-carrying element.

CTX-M-15-producing Klebsiella pneumoniae and Escherichia coli emerged recently in Cameroon. CTX-M-15 was encoded by two different multiresistance plasmids, of which one carried an ISEcp1-bla(CTX-M-15) element flanked by a 5-bp target site duplication and inserted within a Tn2-derived sequence. A truncated form of this element in the second plasmid was identified.

Characterization of In111, a class 1 integron that carries the extended-spectrum beta-lactamase gene blaIBC-1.

A class 1 integron, In111, carried by a self-transferable plasmid from an Escherichia coli clinical strain was characterized. The variable region of In111 constituted an array of gene cassettes encoding the extended-spectrum beta-lactamase IBC-1, the aminoglycoside-modifying enzymes AAC(6')-Ib and ANT(3")-Ia, dihydrofolate reductase I and a putative polypeptide (SMR-2) sharing similarity with the Qac transporters. Transcription of the gene cassettes was driven by a hybrid-type P1 promoter located in a typical 5' conserved segment (CS). The 3'CS included sulI, qacEDelta1, orf5 and orf6. In111 was bounded on the right by an inversely oriented IRt. The 5'CS was preceded by an intact IS26 element followed by an aphA1 gene.