Panton-Valentine Leukocidin Genes Research Articles

Molecular epidemiology of Staphylococcus aureus in post-earthquake northern Haiti

Knowledge of nasal carriage is important in predicting staphylococcal infection, and no information exists regarding the endemicity of Staphylococcus aureus in Haiti. We performed a cross-sectional analysis of S. aureus nasal screening in an acute care, a subacute rehabilitation, and a community setting, with a brief medical and epidemiological history. PCR-positive S. aureus screening nasal cultures underwent molecular analysis for spa type, SCCmec type, and virulence genes (Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin (TSST), and arginine catabolic mobile element (ACME)), and were evaluated for antibiotic susceptibility using commercial tests. Overall carriage rates of 8.4% methicillin-susceptible S. aureus (MSSA) and 2.8% methicillin-resistant S. aureus (MRSA) were identified, with a high rate of tetracycline resistance. TSST and PVL genes were identified in MSSA. MRSA isolates contained no virulence markers. Unique MSSA phenotypes (i.e., linezolid-resistant, vancomycin-sensitive/daptomycin non-susceptible) were identified, as were two PVL-positive ST152 MSSA colonization isolates, previously geographically limited to Africa. We found a low S. aureus carriage rate with complete vancomycin susceptibility and high tetracycline resistance, which has important public health implications with regard to treatment. Additionally, the finding of PVL-positive MSSA isolates, including the expansion of a previously described limited 'divergent' clone, ST152, warrants further evaluation.

Panton-Valentine leukocidin (PVL)-positive health care-associated methicillin-resistant Staphylococcus aureus isolates are associated with skin and soft tissue infections and colonized mainly by infective PVL-encoding bacteriophages.

The emergence of Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) is a public health concern worldwide. PVL is associated with community-associated MRSA and is linked to skin and soft tissue infections (SSTIs). However, PVL genes have also been detected in health care-associated (HA) MRSA isolates. The diseases associated with PVL-positive HA-MRSA isolates and the distributions of PVL-encoding bacteriophages in HA-MRSA have not been determined. In this study, a total of 259 HA-MRSA strains isolated between 2009 and 2012 in China from inpatients with SSTIs, pneumonia, and bacteremia were selected for molecular typing, including staphylococcal cassette chromosome mec typing, multilocus sequence typing, and staphylococcal protein A gene typing. The PVL genes and PVL bacteriophages in the MRSA isolates were characterized by PCR. Among the tested MRSA isolates, 28.6% (74/259) were PVL positive. The high prevalence of PVL-carrying HA-MRSA was observed to be associated with SSTIs but not with pneumonia or bacteremia. The PVL-positive HA-MRSA isolates were colonized mainly by infective PVL phages, namely, Φ7247PVL, ΦSLT, and ΦSa2958. The distribution of PVL-carrying bacteriophages differed geographically. Our study highlights the potential risk of the emergence of multidrug-resistant HA-MRSA strains with increased virulence.

Meticillin-resistant Staphylococcus aureus isolated from Iranian hospitals: virulence factors and antibiotic resistance properties.

Staphylococcus aureus is an important opportunistic pathogen responsible for a variety of diseases. Indiscriminate prescription of antibiotics caused severe antibiotic resistance especially against commonly used drugs. The present investigation was carried out to study the distribution of Panton-Valentine Leukocidin gene, SCCmec types and antibiotic resistance properties of meticillin-resistant Staphylococcus aureus isolated from Iranian hospitals. A total of 132 clinical specimens were collected from two major Iranian hospitals. Samples were cultured and their positive results were subjected to several PCR methods. The patterns of antibiotic resistance were studied using the disk diffusion method. We found that 66 out of 132 samples (50%) were positive for Staphylococcus aureus. The most commonly infected samples were superficial and surgical wounds (66.12%). The incidence of mecA, tetK, ermA, ermC, tetM, aacA-D, linA, msrA, vatA, vatC and vatB antibiotic resistance genes were 80.30%, 34.84%, 30.30%, 25.75%, 24.24%, 19.69%, 7.57%, 7.57%, 6.06%, 3.03% and 1.51%, respectively. Totally, 40.90% of isolates harbored the Panton-Valentine Leukocidin gene. Of 53 mec positive strains, the distribution of SCCmec V, SCCmec III, SCCmec IVa, SCCmec IVc and SCCmec IVb were 28 (52.83%), 13 (24.52%), 6 (11.32%), 4 (7.54%) and 2 (3.77%), respectively. All isolates were resistant to penicillin, cephalothin, cefazoline and ceftriaxone. The high levels of Staphylococcus aureus resistance against commonly used antibiotics as well as high presence of SCCmec types of meticillin-resistant virulent strains of Staphylococcus aureus suggest that infections with these strains require more advanced hospital care with emerging demand for novel antibiotics.

Detection of community-acquired methicillin-resistant Staphylococcus aureus by polymerase chain reaction

Methicillin-resistant Staphylococcus aureus (MRSA) is considered to have emerged from S . aureus through the acquisition of staphylococcal cassette chromosome mec (SCC mec ), which carries the mec A gene for methicillin resistance. Community-acquired Staphylococcus aureus (CA-MRSA) strains carry one of SCC mec types (IV or V). In addition they carry Panton-Valentine leukocidin (PVL) gene. The aim of this study was to evaluate the prevalence of CA-MRSA in Makkah hospitals by detection mec A, SCC mec types (IV and V) and PVL genes. One hundred bacterial isolates were confirmed to carry mec A gene. CA-MRSA was detected in 44% of these MRSA isolates, 30% were SCC mec type IV; 14% were SCC mec type V and 21% were harbored the PVL gene. Molecular methods are useful for diagnosis and typing of MRSA pathogens. CA-MRSA was found to be high in Makkah hospitals and hence the infection-control guidelines for of CA-MRSA are necessary to be improved.

원유시료 중 메티실린 내성 황색포도알균의 분포 및 내성 유전자 특성 분석

원유시료에서 분리한 methicillin 내성 황색포도알균의 분표율과 내성유전자의 분석을 분자수준에서의 실시하였다. 총 698종의 원유시료에서 286개의 포도알균속 세균을 Staphylococcus Medium 110을 이용하여 분리 후 Vitek 2 system을 이용하여 동정한 결과 94개의 황색포도알균을 확인하였다. 94개의 황색포도알균 중 총 7개의 균에서 methicillin 내성 mecA 유전자가 존재함을 확인하였다. Methicillin-resistant Staphylococcus aureus (MRSA)로 확인된 7 균주에 대해 수종의 항생제에 대한 감수성 시험, staphylococcal cassette chromosome mec (SCCmec) typing, 및 병독소유전자인 Panton-Valentine Leukocidin (pvl)유전자를 분석하였다. 그 결과 7종의 mecA 양성 MRSA 모두 ampicillin과 oxacillin에 내성이었으며 teicoplanin, vancomycin 및 ciprofloxacin에는 모두 감수성임을 확인하였다. 한편 SCCmec typing결과 7균 중 1균주는 SCCmec type II로 확인되었고 6균주는 SCCmec type IV로 확인되었으며 병독소 유전자인 pvl유전자는 검출되지 않았다. This study was investigated to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) isolated from raw milk samples and to further study on the molecular characteristics of the MRSA isolates. Using Staphylococcus Medium 110, Staphylococcus spp. were isolated from raw milk samples and further identification was carried by Vitek2 system. Minimum inhibitory concentrations (MICs) of antibiotics were conducted by serial dilution method according to the Clinical Laboratory Standards Institute (CLSI) guideline. For the detection of resistance genes and molecular characterization, PCR reaction was performed by gene specific primers and followed by DNA sequencing. Of the 698 milk samples, 94 Staphylococcus aureus (S. aureus) were identified (94 S. aureus/286 Staphylococcus spp.). Of the 94 S. aureus, seven isolates have mecA, a methicillin resistant gene. mecA positive seven isolates were then characterized by staphylococcal cassette chromosome mec (SCCmec) typing, and Panton-Valentine Leukocidin (pvl) gene using PCR. All of mecA positive isolates were resistant to ampicillin and oxacillin, but sensitive to teicoplanin, vancomycin and ciprofloxacin. One of seven isolates was SCCmec type II and six isolates were type IV and all seven isolates were pvl gene negative.

Foods confiscated from non-EU flights as a neglected route of potential methicillin-resistant Staphylococcus aureus transmission

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in food-producing animals has provoked a great concern in the presence of MRSA in associated foodstuff. In this study, we have assessed for the first time the presence of MRSA in food confiscated from non-EU flights. We performed a search for MRSA among 195 food samples confiscated from passengers on flights from twenty-one non-EU countries in 2012 and 2013. One hundred and seventeen meat samples of diverse animal origin (including antelope, beef, chicken, duck, guinea pig, pork, rodents, and turkey), 75 dairy products (74 cheeses and 1 butter) and 3 eggs were analyzed. All S. aureus were studied by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. MRSA isolates were further characterized by multilocus sequence typing (MLST), SCCmec typing, and tested for the presence of Panton–Valentine leukocidin (PVL) virulence factors. Overall, 66 food samples were positive for S. aureus (33.9%). Six S. aureus strains were MRSA (9.1%), all of them in flights from Bolivia (and 5 from the same passenger). Among methicillin-sensitive S. aureus (MSSA) (60 out of 66S. aureus strains), 44.1% were resistant to penicillin, 10.2% to tetracycline, 8.5% were resistant to aminoglycosides (amikacin and tobramycin) and 3.4% exhibited the M phenotype. MRSA isolates were sensitive to all non-β-lactam antibiotics tested. SmaI-PFGE analysis provided 40 genotypes among the S. aureus isolates (three genotypes among the six MRSA). Five MRSA isolates belonged to ST8 and harboured SCCmec type IVc as well as PVL genes. One isolate belonged to ST1649, harboured SCCmec type IVc and tested negative for the presence of the PVL genes. In conclusion, in this study, we report for the first time the presence of CA-MRSA in food confiscated from non-EU flights: ST8/ST1649-MRSA-IV. These results confirm the illegal entrance of food as a neglected route of transmission as well as the dissemination of successful CA-MRSA lineages among countries via illegal foods. As a result, illegally imported food could play a role in the prevalence and evolution of MRSA clones in the community.

Community-associated methicillin-resistant Staphylococcus aureus clonal complex 80 type IV (CC80-MRSA-IV) isolated from the Middle East: a heterogeneous expanding clonal lineage.

BackgroundThe emergence of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) has caused a change in MRSA epidemiology worldwide. In the Middle East, the persistent spread of CA-MRSA isolates that were associated with multilocus sequence type (MLST) clonal complex 80 and with staphylococcal cassette chromosome mec (SCCmec) type IV (CC80-MRSA-IV), calls for novel approaches for infection control that would limit its spread.Methodology/Principal FindingsIn this study, the epidemiology of CC80-MRSA-IV was investigated in Jordan and Lebanon retrospectively covering the period from 2000 to 2011. Ninety-four S. aureus isolates, 63 (67%) collected from Lebanon and 31 (33%) collected from Jordan were included in this study. More than half of the isolates (56%) were associated with skin and soft tissue infections (SSTIs), and 73 (78%) were Panton-Valentine Leukocidin (PVL) positive. Majority of the isolates (84%) carried the gene for exofoliative toxin d (etd), 19% had the Toxic Shock Syndrome Toxin-1 gene (tst), and seven isolates from Jordan had a rare combination being positive for both tst and PVL genes. spa typing showed the prevalence of type t044 (85%) and pulsed-field gel electrophoresis (PFGE) recognized 21 different patterns. Antimicrobial susceptibility testing showed the prevalence (36%) of a unique resistant profile, which included resistance to streptomycin, kanamycin, and fusidic acid (SKF profile).ConclusionsThe genetic diversity among the CC80 isolates observed in this study poses an additional challenge to infection control of CA-MRSA epidemics. CA-MRSA related to ST80 in the Middle East was distinguished in this study from the ones described in other countries. Genetic diversity observed, which may be due to mutations and differences in the antibiotic regimens between countries may have led to the development of heterogeneous strains. Hence, it is difficult to maintain “the European CA-MRSA clone” as a uniform clone and it is better to designate as CC80-MRSA-IV isolates.

Molecular epidemiology of nasal isolates of methicillin-resistant Staphylococcus aureus from Jordan.

Asymptomatic carriage of methicillin-resistant Staphylococcus aureus (MRSA) can predispose the host to a wide range of infections. To inform public health strategies, this study sought to determine the prevalence and the phenotypic and genotypic characteristics of MRSA from nasal swabs of health care workers (HCWs) and other healthy individuals in Jordan. Overall, 716 nasal swabs were collected from 297 HCWs, 141 adults and 278 children in the community. MRSA was recovered from 56 (7.8%) nasal swabs, which represented carriage rates of 10.1%, 4.3% and 7.2% among HCWs, adults and children, respectively. The MRSA isolates were resistant to oxacillin (100%), erythromycin (42.8%), tetracycline (37.5%), clindamycin (5.3%), fucidin (5.3%), and ciprofloxacin (3.5%). A total of 17 different spa types belonging to eight different clonal complexes (CCs) were identified. All isolates were mecA positive, and mecC-MRSA was not detected. Analysis of the staphylococcal cassette chromosome mec (SCCmec) elements revealed that the majority (54; 96.4%) of the samples harbored the smaller type IV and V elements (the most common were SCCmec IVa or IVc, and there were two each of the IVg and V elements), and two were nontypable. The genes for Panton-Valentine leukocidin (luk-PV) were detected in 5.4% of the study isolates. A tst-positive, CC22-MRSA-SCCmecIVa clone (spa type t223) was identified as the dominant MRSA lineage among the nasal carriage isolates from both HCWs and other individuals (adults and children) in the community. These findings provide important information for public health personnel for the formulation of effective infection prevention and control strategies. Studies to further our understanding of the distribution, pathogenicity, transmissibility and fitness of this lineage would be prudent.

Molecular epidemiology and antimicrobial resistance of methicillin-resistant Staphylococcus aureus bloodstream isolates in Taiwan, 2010.

The information of molecular characteristics and antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) is essential for control and treatment of diseases caused by this medically important pathogen. A total of 577 clinical MRSA bloodstream isolates from six major hospitals in Taiwan were determined for molecular types, carriage of Panton-Valentine leukocidin (PVL) and sasX genes and susceptibilities to 9 non-beta-lactam antimicrobial agents. A total of 17 genotypes were identified in 577 strains by pulsotyping. Five major pulsotypes, which included type A (26.2%, belonging to sequence type (ST) 239, carrying type III staphylococcal chromosomal cassette mec (SCCmec), type F (18.9%, ST5-SCCmecII), type C (18.5%, ST59-SCCmecIV), type B (12.0%, ST239-SCCmecIII) and type D (10.9%, ST59-SCCmecVT/IV), prevailed in each of the six sampled hospitals. PVL and sasX genes were respectively carried by ST59-type D strains and ST239 strains with high frequencies (93.7% and 99.1%, respectively) but rarely detected in strains of other genotypes. Isolates of different genotypes and from different hospitals exhibited distinct antibiograms. Multi-resistance to ≥3 non-beta-lactams was more common in ST239 isolates (100%) than in ST5 isolates (97.2%, P = 0.0347) and ST59 isolates (8.2%, P<0.0001). Multivariate analysis further indicated that the genotype, but not the hospital, was an independent factor associated with muti-resistance of the MRSA strains. In conclusion, five common MRSA clones with distinct antibiograms prevailed in the major hospitals in Taiwan in 2010. The antimicrobial susceptibility pattern of invasive MRSA was mainly determined by the clonal distribution.

Oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA), a hidden resistant mechanism among clinically significant isolates in the Wessex region/UK.

Methicillin-resistant Staphylococcus aureus (MRSA) is defined as S. aureus genetically having the mecA or mecC genes or phenotypically showing minimum inhibitory concentration (MIC) of oxacillin higher than 2mg/L. However, recently, cefoxitin/oxacillin-susceptible mecA-positive S. aureus (OS-MRSA) has been reported worldwide. Little is known about the prevalence and virulence of these strains among clinically significant isolates in the UK. The aims were to (1) investigate the prevalence of OS-MRSA in seven major hospitals in the Wessex region/UK from a cohort of 500 clinically significant phenotypically identified MSSA isolates, (2) genetically characterise OS-MRSA strains by pulsed-field gel electrophoresis (PFGE) and compare these to common UK epidemic strains; and (3) to determine Panton-Valentine leukocidin (PVL; lukFS) gene carriage rates among these isolates. OS-MRSA was found in six isolates (1.2%) of phenotypically identified and reported MSSA isolates by conventional methods. PFGE showed OS-MRSA strains to be genetically diverse and distinct from the common UK epidemic strains EMRSA-15 and EMRSA-16. None of these OS-MRSA stains carried the genes encoding PVL; however, overall positivity rate for PVL was 4.4%, much higher than the nationally reported rates of 2% in the UK. There are still many unknowns regarding phenotypic and/or genetic characterization of the emerging OS-MRSA isolates in the UK and worldwide. Data regarding their epidemiology and optimal therapy for infection are limited and need further investigation not only in the UK, but also worldwide, as it is likely to have an impact on the empirical treatment of S. aureus infections.

Methicillin resistant Staphylococcus aureus nasal colonization among secondary school students at Duhok City-Iraq

Objective: Methicillin-resistant Staphylococcus aureus (MRSA) widely distributed in hospitals around the world. There is strong relationship between disease development and S. aureus nasal carriage. The aim of this study was to evaluate the prevalence and epidemiology of nasal colonization with S. aureus and MRSA in the community of Duhok city, Iraq. Methods: 489 students aged 16 to18 years were included. Nasal swab samples were collected followed by antimicrobial susceptibility test. MRSA isolates were selected and investigated for the mecA gene. Also the prevalence of PantonValentine Leukocidin (PVL) gene was also studied. Results: A total of 90 (18.4%) out of 489 (18.4%) of the students were found to be colonized by S. aureus. Only 10 (2.04%) of the students were found to be MRSA carrier. All MRSA isolates were sensitive to Vancomycin. PLV gene was detected in one MRSA strain. Conclusion: This is the first study investigating S. aureus colonization in students in the Duhok city. Nasal carriage of S. aureus and MRSA is comparable with reports from elsewhere. Fortunately, all trains included in our study were sensitive to vancomycin. Further research is needed to examine the SCCmec elements and the evolution of MRSA over the time. J Microbiol Infect Dis 2014;4(2): 59-63

Multiplex real-time PCR for detection of Staphylococcus aureus, mecA and Panton-Valentine Leukocidin (PVL) genes from selective enrichments from animals and retail meat.

The aim of this study was to compare a real-time PCR assay, with a conventional culture/PCR method, to detect S. aureus, mecA and Panton-Valentine Leukocidin (PVL) genes in animals and retail meat, using a two-step selective enrichment protocol. A total of 234 samples were examined (77 animal nasal swabs, 112 retail raw meat, and 45 deli meat). The multiplex real-time PCR targeted the genes: nuc (identification of S. aureus), mecA (associated with methicillin resistance) and PVL (virulence factor), and the primary and secondary enrichment samples were assessed. The conventional culture/PCR method included the two-step selective enrichment, selective plating, biochemical testing, and multiplex PCR for confirmation. The conventional culture/PCR method recovered 95/234 positive S. aureus samples. Application of real-time PCR on samples following primary and secondary enrichment detected S. aureus in 111/234 and 120/234 samples respectively. For detection of S. aureus, the kappa statistic was 0.68–0.88 (from substantial to almost perfect agreement) and 0.29–0.77 (from fair to substantial agreement) for primary and secondary enrichments, using real-time PCR. For detection of mecA gene, the kappa statistic was 0–0.49 (from no agreement beyond that expected by chance to moderate agreement) for primary and secondary enrichment samples. Two pork samples were mecA gene positive by all methods. The real-time PCR assay detected the mecA gene in samples that were negative for S. aureus, but positive for Staphylococcus spp. The PVL gene was not detected in any sample by the conventional culture/PCR method or the real-time PCR assay. Among S. aureus isolated by conventional culture/PCR method, the sequence type ST398, and multi-drug resistant strains were found in animals and raw meat samples. The real-time PCR assay may be recommended as a rapid method for detection of S. aureus and the mecA gene, with further confirmation of methicillin-resistant S. aureus (MRSA) using the standard culture method.

SCCmec types and pvl gene in methicillin-resistant Staphylococcus aureus strains from children hospitalized in a tertiary care hospital in Mexico.

The aim of this study was to determine the prevalence, SCCmec types, presence of the Panton-Valentine leukocidin (PVL) gene, and susceptibility to antibiotics of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from hospitalized children. From August 2009 to September 2011, 291 S. aureus strains were isolated from normally sterile body sites, of which 190 (65%) were MRSA. One hundred and two of the MRSA strains were genetically evaluated. SCCmec genotypes were identified by M-PCR and the PVL gene (pvl) by end-point PCR. Resistance to erythromycin, rifampicin, clindamycin, and trimethoprim-sulfamethoxazole (SXT) was assessed by Kirby-Bauer disk diffusion method in accordance with the Clinical and Laboratory Standards Institute guidelines of 2012. Of the 102 strains evaluated, 97 (95%) were SCCmec type II, 5 (5%) were SCCmec type IVa, and all (100%) were pvl-negative. Resistance to erythromycin, clindamycin, rifampicin, and SXT was 97%, 95%, 0%, and 0%, respectively. The prevalence of hospital-acquired MRSA was high. SCCmec type II was predominant and the pvl gene appeared not to play any role in the virulence of the MRSA strains from hospitalized children.

Insights into nasal carriage of Staphylococcus aureus in an urban and a rural community in Ghana.

The epidemiology of Staphylococcus aureus in the community in Ghana was never investigated prior to this study. The aims of the study were: i) to assess prevalence of nasal S. aureus carriage in Ghanaian people living in an urban and a rural area, and ii) to identify phenotypic and genotypic traits of strains isolated from the two communities. Nasal swabs were collected from healthy individuals living in an urban community situated in the suburb of the capital city, Accra (n = 353) and in a rural community situated in the Dangme-West district (n = 234). The overall prevalence of nasal carriage was 21% with a significantly higher prevalence in the urban (28%) than in the rural community (11%) (p<0.0001). The levels of antimicrobial resistance were generally low (<5%) except for penicillin (91%) and tetracycline (25%). The only two (0.3%) MRSA carriers were individuals living in the urban area and had been exposed to hospitals within the last 12 months prior to sampling. Resistance to tetracycline (p = 0.0009) and presence of Panton-Valentine leukocidin (PVL) gene (p = 0.02) were significantly higher among isolates from the rural community compared to isolates from the urban community. Eleven MLST clonal complexes (CC) were detected based on spa typing of the 124 S. aureus isolates from the two communities: CC8 (n = 36), CC152 (n = 21), CC45 (n = 21), CC15 (n = 18), CC121 (n = 6), CC97 (n = 6), CC30 (n = 5), CC5 (n = 5), CC508 (n = 4), CC9 (n = 1), and CC707 (n = 1). CC8 and CC45 were less frequent in the rural area than in the urban area (p = 0.02). These results reveal remarkable differences regarding carriage prevalence, tetracycline resistance, PVL content and clonal distribution of S. aureus in the two study populations. Future research may be required to establish whether such differences in nasal S. aureus carriage are linked to socio-economic differences between urban and rural communities in this African country.

An outbreak of community-associated methicillin-resistant Staphylococcus aureus infection in a boarding school in Hong Kong Special Administrative Region (China).

In November 2012, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections affecting students at a boarding school in Hong Kong Special Administrative Region (China) was detected. A case was defined as any student or staff notified with MRSA infection from 25 October 2012 to 5 July 2013 with the clinical isolate being of staphylococcal cassette chromosome mec type IV or V and positive for Panton-Valentine leukocidin gene. We conducted field investigations, advised on control measures and enhanced surveillance for skin and soft tissue infections at the school. Decolonization therapies were offered to all cases and contacts, and carrier screening was conducted. There were five cases; two (40%) were hospitalized and three (60%) required surgical treatments. Initial screening comprised 240 students and 81 staff members. Overall, four cases (80%) plus eight other students (3.3%) were carriers, with eight of 12 (66.7%) from the same dormitory. All staff members screened negative. After intensified control measures, the number of students screened positive for CA-MRSA decreased from nine to one with no more cases identified in the school. Identification of carriers, decolonization therapy, monitoring of cases and contacts and strengthening of environmental and personal hygiene were control measures that helped contain this CA-MRSA outbreak in a boarding school in Hong Kong Special Administrative Region (China).

The clinical and molecular epidemiology of Staphylococcus aureus infections in Fiji

BackgroundThere are few data describing the microbiology and genetic typing of Staphylococcus aureus that cause infections in developing countries.MethodsIn this study we observed S. aureus infections in Pacific Island nation of Fiji in both the community and hospital setting with an emphasis on clonal complex (CC) genotyping and antimicrobial susceptibility.ResultsS. aureus was commonly found in impetigo lesions of school children and was recovered from 57% of impetigo lesions frequently in conjunction with group A streptococcal infection. Methicillin-resistant S. aureus (MRSA) comprised 7% (20/299) of isolates and were all non-multi-resistant and all genotyped as CC1. In contrast, there was a diverse selection of 17 CCs among the 105 genotyped methicillin-susceptible S.aureus (MSSA) strains. Isolates of the rare, phylogenetically divergent and non-pigmented CC75 lineage (also called S.argenteus) were found in Fiji.From hospitalized patients the available 36 MRSA isolates from a 9-month period were represented by five CCs. The most common CCs were CC1 and CC239. CC1 is likely to be a community-acquired strain, reflecting what was found in the school children, whereas the CC239 is the very successful multi-drug resistant MRSA nosocomial lineage. Of 17 MSSA isolates, 59% carried genes for Panton-Valentine leukocidin. The S. aureus bacteraemia incidence rate of 50 per 100,000 population is among the highest reported in the literature and likely reflects the high overall burden of staphylococcal infections in this population.ConclusionsS. aureus is an important cause of disease in Fiji and there is considerable genotypic diversity in community skin infections in Fijian schoolchildren. Community acquired- (CA)- MRSA is present at a relatively low prevalence (6.7%) and was solely to CC1 (CA-MRSA). The globally successful CC239 is also a significant pathogen in Fiji.

Staphylococcal cassette chromosome mec typing of and detection of PVL gene in 84 methicillin-resistant Staphylococcus aureus isolates from patients with infectious skin diseases

Objective To determine staphylococcal cassette chromosome mec (SCCmec) types and detect panton-valentine leukocidin (PVL) gene in methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients with infectious skin diseases.Methods Staphylococcus aureus was isolated from lesion exudate of patients with infectious skin diseases between June 2010 and July 2012 in different departments of Affiliated Hospital of Inner Mongolia Medical University.General and medical information on the patients was collected as well.PCR was performed to detect mecA gene in MRSA strains,and multiplex PCR was conducted to determine SCCmec type and detect PVL gene in mecA gene-positive strains.Results A total of 95 MRSA strains were isolated from these patients with infectious skin diseases,and mecA gene was found in 84 out of these strains.Among these mecA-positive strains,5 carried PVL gene,69 (86.3％) were identified as SCCmec type Ⅲ,3 (3.6％) as SCCmec type Ⅰ,8 (9.52％) as SCCmec type Ⅳ,4 (4.8％) were non-typeable,and no strain was identified as SCCmec type Ⅱ or W.Conclusions Hospital-acquired (HA)-MRSA predominates in MRSA strains causing infectious skin diseases,with SCCmec type Ⅲ as the major SCCmec type.Both HA and community-acquired (CA) MRSA strains carry PVL toxin. Key words: Infection; Skin; Genes, SCCmec; PVL toxin

High-Density Livestock Production and Molecularly Characterized MRSA Infections in Pennsylvania

Background: European studies suggest that living near high-density livestock production increases the risk of sequence type (ST) 398 methicillin-resistant Staphylococcus aureus (MRSA) colonization. To our knowledge, no studies have evaluated associations between livestock production and human infection by other strain types.Objectives: We evaluated associations between MRSA molecular subgroups and high-density livestock production.Methods: We conducted a yearlong 2012 prospective study on a stratified random sample of patients with culture-confirmed MRSA infection; we oversampled patients from the Geisinger Health System with exposure to high-density livestock production in Pennsylvania. Isolates were characterized using S. aureus protein A (spa) typing and detection of Panton-Valentine leukocidin (PVL) and scn genes. We compared patients with one of two specific MRSA strains with patients with all other strains of MRSA isolates, using logistic regression that accounted for the sampling design, for two different exposure models: one based on the location of the animals (livestock model) and the other on crop field application of manure (crop field model).Results: Of 196 MRSA isolates, we identified 30 spa types, 47 PVL-negative and 15 scn-negative isolates, and no ST398 MRSA. Compared with quartiles 1–3 combined, the highest quartiles of swine livestock and dairy/veal crop field exposures were positively associated with community-onset-PVL-negative MRSA (CO-PVL-negative MRSA vs. all other MRSA), with adjusted odds ratios of 4.24 (95% CI: 1.60, 11.25) and 4.88 (95% CI: 1.40, 17.00), respectively. The association with CO-PVL-negative MRSA infection increased across quartiles of dairy/veal livestock exposure (trend p = 0.05).Conclusions: Our findings suggest that other MRSA strains, beyond ST398, may be involved in livestock-associated MRSA infection in the United States.Citation: Casey JA, Shopsin B, Cosgrove SE, Nachman KE, Curriero FC, Rose HR, Schwartz BS. 2014. High-density livestock production and molecularly characterized MRSA infections in Pennsylvania. Environ Health Perspect 122:464–470; http://dx.doi.org/10.1289/ehp.1307370

Carriage of Staphylococcus species in the veterinary visiting dog population in mainland UK: Molecular characterisation of resistance and virulence

This study investigated the prevalence of nasal carriage of staphylococci in dogs and determined the characteristics of the isolates. A total of 724 dogs from 87 veterinary practices across the mainland UK were screened for carriage of Staphylococcus spp. All isolates were examined for meticillin resistance (MR) and the presence of the mecA gene investigated in those isolates showing resistance. All coagulase-positive staphylococci and MR coagulase-negative staphylococci (MRCoNS) were subjected to antimicrobial susceptibility testing. Spa typing and DNA microarray analysis of resistance and virulence genes was carried out on all MR S. aureus (MRSA) and a subset of meticillin susceptible S. aureus (MSSA). Staphylococci were isolated from 399 (55.1%) of the dogs; only seven (1%) carried MRSA, all of which were identified as the dominant UK healthcare-associated strain (EMRSA-15, ST22). MSSA was identified in 47 (6.5%) dogs, the sequence types of which have been suggested as precursors to successful MRSA clones. Forty (5.5%) dogs carried MRCoNS, while no dogs carried MR S. pseudintermedius, although this is increasingly reported in mainland Europe. Resistance to antimicrobials among the isolates varied between species, with multidrug resistance (MDR) in 87.5% of MRCoNS and 21.8% of coagulase positive staphylococci. Microarray analysis of MRSA and a subset of MSSA isolates identified numerous virulence genes associated with pathogenesis, which are commonly identified in isolates of human origin. However, no isolates carried Panton-Valentine leukocidin (PVL) genes. This study suggests that MRSA carriage is low in the vet visiting dog population, but there is a diverse range of virulence and resistance determinants in canine S. aureus and MRCoNS isolates.

Non-Multidrug-Resistant, Methicillin-Resistant Staphylococcus aureus Causing Infection in Health-care Facilities in Southern Brazil

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is usually susceptible to a variety of non-beta-lactam drugs. These isolates commonly display SCCmecIV and are associated with community-acquired infections. More recently, CA-MRSA has been isolated from health-care-associated diseases. We categorize isolates resistant only to oxacillin or oxacillin plus no more than 3 non-beta-lactam antibiotics according to clinical and epidemiological characteristics, from a hospital in Porto Alegre, and performed a combination of molecular techniques including mecA, SCCmec, Panton-Valentine leukocidin (PVL) detection and Pulsed-field gel electrophoresis (PFGE). A total of twenty-five patients with non-multidrug-resistant MRSA were studied. Nineteen (76%) came from skin and soft tissue infections. All isolates presented SCCmec type IV (being 19/25 IVc) whereas the PFGE profile most frequently found was OSCP-like (15/25). The presence of international clones USA400, USA300 was also verified. Comparing the results of clonal type with source, origin, type of SCCmec, presence the PVL gene and antimicrobial resistance we observed that OSCP-like PFGE profile was associated with skin and soft tissue infections (P=0.0012) and that this clonal group was strongly associated with the presence of PVL gene (P<0.001). This study shows a clonal diversity of CA-MRSA and strengths the concept that these isolates emerged globally from different backgrounds.