PVL Toxin Research Articles

Distribution of SCCmec Types in Methicillin-Resistant Staphylococcus aureus Isolated from Burn Patients

Background: Methicillin resistance Staphylococcus aureus (MRSA) isolates have been recognized as one of the most important causes of infection in burn patients that have recently shown a frequent and rapid development of antibiotic resistance. Objectives: The present study described the distribution of different SCCmec types and antibiotic resistance pattern among MRSA strains isolated from burn patients in a referral burn center in Tehran, Iran. Methods: During a 12-month study, 189 MRSA isolates were obtained from burn patients. Standard culture and biochemical tests were used for identification of MRSA isolates. The antibiotic susceptibility testing was performed using disc diffusion method and the presence of mecA, nucA, pvl, and tst encoding genes was determined using PCR method. In addition, the different SCCmec types were determined using multiplex PCR. Results: All the MRSA isolates were observed to be resistant to amoxicillin and penicillin and sensitive to linezolid, teicoplanin, and vancomycin. The rates of resistance to other antibiotics varied from 86.2% for amikacin to 17.5% for quinupristin-dalfopristin. MDR was observed in all the isolates. Six different antimicrobial resistance patterns were observed among our isolates. Based on the multiplex PCR assay, the two different SCCmec types were detected as 71.4% type III and 28.6% type IV. In total, 8.5% of isolates harbored pvl toxin encoding gene all of which belonging to SCCmec type IV. Furthermore, 33 isolates (17.5%) harbored tst encoding gene. Conclusions: The results showed low diversity of SCCmec type among circulating MRSA in the burn center with relatively high prevalence of SCCmec III. These findings support the need for more studies to elucidate distribution of different SCCmec types among MRSA isolated from burn patients.

Methicillin resistant Staphylococcus aureus isolated from meat raw in Cartagena, Colombia

To determine the prevalence of Methicillin Resistant Staphylococcus aureus (MRSA) isolated in establishments that commercialize raw ground beef and pork chops in Cartagena- Colombia. 160 samples were analyzed through microbiological cultures in Baire Parcker agar, and it was determined the presence of mecA gen that codifies the methicillin resistance and the pvl that codifies the Panton- Valentine leukocidin toxin (PVL) by the multiplex PCR technique. The antibiotic susceptibility profile for MRSA strains was realized by automatized methods and for MSSA strains it was used Kirby Bauver. 66 samples were confirmed as S. aureus by PCR. The prevalence of MRSA was 7.5% and 33.8% of MSSA. The 66% of the strains were isolated from raw ground beef and the 34% of pork chop meat. The isolations presented about 2 – 12% of multi-resistance to the antibiotics used. The MRSA showed resistance to amoxicillin- clavulanate (57%), ampicillin-sulbactam and cefazolin (85%), erythromycin and clindamycin (7%), tetracycline (35%). The 10% of the isolated strains had the gen of PVL toxin and the 71% of those were identified in samples of raw pork meat and the 28% in raw ground beef. This study reports for the first time, how meat raw products commercialized in the city of Cartagena could build a dissemination source of MRSA carrier of PVL toxin that could generate a public health disease.

CIRCULATING CLONES OF COMMUNITY-ACQUIRED METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (CA-MRSA) IN WESTERN AUSTRALIA IN THE PAST 11 YEARS (2002-2013)

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most complicated problems in infection control and disease prevention. Imported strains or group of similar strains called clones were introduced from other states within Australia and also from other countries. Western Australia (WA) MRSA clones known to be the most predominant clones circulating in Western Australia (WA). However, MRSA strains originally from other states and countries outside Australia (imported) have increased in number in the last decades. The aim of this study was to examine the epidemiology of CA MRSA clones in Western Australia for the past 11 year’s period (2003-2013). There were 10 predominant clones of CA-MRSA circulating in WA with WA MRSA-1 (32,82%), Queensland (22,67 %) and WA MRSA-2 (22,67 %) clones as the top three predominant clones. The percentage of PVL positive CA-MRSA clones such as Queensland (Qld) clone has been increasing significantly (R2=0,67) from 2,38 % in 2002 to 25,69% in 2013. In contrast, the percentages of two major PVL negative clones, WA MRSA-1 and WA MRSA 2, have been decreasing nearly by half from 52,38 % to 27,71 % and 30,95 % to 16,59 % respectively in the last 11 years. PVL positive clones have been introduced in WA from other states and overseas in the last eleven years. Due to the virulence factor of PVL toxin, the emergence of PVL positive CA-MRSA should be considered as public health concerns.

Investigation of Methicillin Resistance and Panton-Valentine Leukocidin in Staphylococci Isolated from Bovine Mastitis

Background: Mastitis, which is inflammation of the mammary gland, is among the most important diseases in dairy herds resulting in reductions of milk yield and milk quality. Although several groups of microorganisms have been reported as etiological agents of mastitis, Staphylococci are the most frequently isolated bacteria from bovine mastitic milk samples. The aim of this study was to isolate the Staphylococcus species from bovine mastitis, investigate the mecA ve pvl genes in isolated species by PCR and determine the antibiotic resistance of methicillin resistant strains to some antibiotics commonly used in veterinary field.Materials, Methods & Results: In the present study, 972 half-udder milk samples (n = 757 CMT positive, n = 215 CMT negative) were used from 251 lactating cows from 34 different enterprises located center town and villages of Ödemiş, İzmir. Ten microliters of each milk sample was inoculated onto Columbia blood agar, containing 7% of sheep blood and incubated under aerobic conditions for 24-48 h at 37°C. The certain identification of Staphylococcus isolates was achieved using Crystal™ Identification Systems Gram-Positive ID kit. Bacterial DNAs were extracted from all strains using boiling method and strains were screened for the presence of 16S rDNA, mecA and pvl genes by PCR. The antimicrobial resistance of MRS species was determined by using disc diffusion method. A total of 182 (18.72%) Staphylococcus strains were isolated from 972 half-udder milk samples. Of 182 Staphylococcus strains, 137 (75.27%) and 45 (24.73%) were detected as CPS and CNS, respectively. Among the 11 different Staphylococcus species, S. intermedius (42.30%) was the most common species isolated, followed by S. aureus (32.97%) and S. saprophyticus (10.99%). The mecA positivity was found in only 4 (2.2%) S. intermedius strains, while pvl toxin gene was determined in none of the strains. Four MR S. intermedius strains were resistant to oxacillin and cefoxitin. The resistance was also found to erythromycin (50%), rifampicin (25%), gentamicin (25%), tetracycline (25%) and trimethoprim/sulfamethoxazole (25%) in the isolates.Discussion: In this study, S. intermedius had the highest isolation rate and this finding was considered remarkable. Generally, in mastitis diagnostics all CPS isolates are classified as S. aureus. In our study, the certain identification of all CPS may explain the high isolation rate of S. intermedius. The sampling method may also be the reason of higher isolation rate for S. intermedius in accordance with the most common ones causing mastitis. All of mecA positive strains were S. intermedius and this was the another remarkable finding of our study. Because similar result was seen in only one study from Korea, while the investigation finding related to MR S. intermedius was not determined in Turkey. However, the mecA positivity found in our study was lower than the other author’s isolation rate. The difference between the sample size, geographical variations and diversity in strains may be the causes of this discrepancy. It was investigated pvl toxin gene in 182 Staphylococcus strains by PCR and found this gene in none of strains. According to this finding, it was considered that pvl gene may have not an efficient role in the pathogenesis of mastitis in terms of sampled animals and sampling area. Antibiotic resistance of 4 MR S. intermedius strains against various antibiotics commonly used in Turkey was investigated. Of methicillin resistant strains, 2, 1 and 1 were resistant to 3, 6 and 5 antibiotics, respectively. It was considered that geographical differences, number of tested isolates and diversity in MR strains may be effective on the antibiotic resistance levels. This is the first study showing the presence of mecA gene in S. intermedius strains isolated from bovine mastitic milk samples in Turkey.

Prevalence of MRSA Nasal Carriage in Patients Admitted to a Tertiary Care Hospital in Southern India.

Infections with MRSA, both community and hospital acquired, are well established and the source of infection is often a carrier. There are very few studies showing the magnitude of MRSA nasal colonization among healthy persons from the community. This study was conducted to detect the prevalence of MRSA nasal carriage in patients who did not have any known risk factors associated with HA- MRSA colonization, admitted to a tertiary care centre in Kerala. Nasal swabs were collected from patients within 24 hours of admission. Specimen were inoculated on chromogenic agar (HiCrome MeReSa agar-HiMedia) for MRSA screening. Isolates were then subjected to antibiotic sensitivity tests, SCCmec typing and PVL gene detection. Out of 683 patients, 16 carried MRSA in their nares (2.3%). Of the 16 strains 13 (81.25 %) strain were SCCmec type III and one belonged to SCCmec type IV (6.25 %). Two strains failed to amplify SCCmec genes. Three strains carried genes for PVL toxin (18.75%). With a better understanding of the complex epidemiology of MRSA it is increasingly apparent that demarcations between the HA and CA phenotypes are not as clear cut as previously thought. In this study of nasal carriage of MRSA in the community we have demonstrated prevalence consistent with published data. Most isolates however were shown to belong to the type conventionally assigned to HA-MRSA.

Analysis of the features of 45 identified CRISPR loci in 32 Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a common pathogen that can cause serious infections, even death. Because of the horizontal gene transfer (HGT) of antibiotic resistance genes, the drug resistant condition is becoming increasingly prevalent. Recently, an adaptive immunity system, named clustered regularly interspaced short palindromic repeats (CRISPR), was discovered and demonstrated to confer a defense against foreign invading elements that may carry the antibiotic resistance genes. In this study, we reveal the features of 45 identified CRISPR loci and the CRISPR associated gene (Cas) in 32 S. aureus strains from CRISPR database. Five spacers of S. aureus 08BA02176 and MSHR1132 were homologous with foreign genetic sequences from phages or plasmids, even containing a spacer sequence identical to part of some phages' genomes containing lukPV gene that encodes the PVL toxin. Many S. aureus strains with the same CRISPR type shared the same MLST type. CRISPR loci that had 3 or more similar protein loci mostly belonged to the same CRISPR type. We came to the conclusion that the CRISPR/Cas of strains 08BA02176 and MSHR1132 were inherited from a common ancestor or recombined from Staphylococcus lugdunensis. CRISPR loci can be mobilized and can transfer among different but closely related species, and the same types of MLST strains exhibit a higher affinity to the same types of CRISPR loci. Bacteriophages may be the predominant challenge facing S. aureus. The CRISPR/Cas structure may limit the transmission of bacterial virulence among S. aureus.

Detection of Methicillin Resistance and Various Virulence Factors in Staphylococcus aureus Strains Isolated from Nasal Carriers.

Staphylococus aureus can be found as a commensal on skin and nasal flora or it may cause local and invasive infections. S. aureus has a large number of virulence factors. To investigate the methicillin resistance and frequency of various virulence factors in S. aureus nasal isolates. Descriptive study. Nasal samples collected from university students were cultured in media. S. aureus was identified by conventional methods and the Staphyloslide latex test (Becton Dickinson, Sparks, USA). Antibiotic susceptibility tests were conducted, and the methicillin resistance was determined. The mecA, nuc, pvl and staphylococcal toxin genes were examined by polymerase chain reaction (PCR). S. aureus was isolated in 104 of 600 (17.3%) nasal samples. In total, 101 (97.1%) S. aureus isolates were methicillin-sensitive and the remaining 3 (2.9%) were methicillin-resistant. Furthermore, all but five isolates carried at least one staphylococcal enterotoxin gene, with seg being predominant. The tst and eta genes were determined in 29 (27.9%), and 3 (2.9%) isolates, respectively. None of the S. aureus isolates harbored see, etb, and pvl genes. A moderate rate of S. aureus carriage and low frequency of MRSA were detected in healthy students. S. aureus isolates had a high prevalence of staphylococcal enterotoxin genes and the tst gene. In this study, a large number of virulence factors were examined in S. aureus nasal isolates, and the data obtained from this study can be used for monitoring the prevalence of virulence genes in S. aureus strains isolated from nasal carriers.

Linezolid has unique immunomodulatory effects in post-influenza community acquired MRSA pneumonia.

IntroductionPost influenza pneumonia is a leading cause of mortality and morbidity, with mortality rates approaching 60% when bacterial infections are secondary to multi-drug resistant (MDR) pathogens. Staphylococcus aureus, in particular community acquired MRSA (cMRSA), has emerged as a leading cause of post influenza pneumonia.HypothesisLinezolid (LZD) prevents acute lung injury in murine model of post influenza bacterial pneumoniaMethodsMice were infected with HINI strain of influenza and then challenged with cMRSA at day 7, treated with antibiotics (LZD or Vanco) or vehicle 6 hours post bacterial challenge and lungs and bronchoalveolar lavage fluid (BAL) harvested at 24 hours for bacterial clearance, inflammatory cell influx, cytokine/chemokine analysis and assessment of lung injury.ResultsMice treated with LZD or Vanco had lower bacterial burden in the lung and no systemic dissemination, as compared to the control (no antibiotic) group at 24 hours post bacterial challenge. As compared to animals receiving Vanco, LZD group had significantly lower numbers of neutrophils in the BAL (9×103 vs. 2.3×104, p < 0.01), which was associated with reduced levels of chemotactic chemokines and inflammatory cytokines KC, MIP-2, IFN-γ, TNF-α and IL-1β in the BAL. Interestingly, LZD treatment also protected mice from lung injury, as assessed by albumin concentration in the BAL post treatment with H1N1 and cMRSA when compared to vanco treatment. Moreover, treatment with LZD was associated with significantly lower levels of PVL toxin in lungs.ConclusionLinezolid has unique immunomodulatory effects on host inflammatory response and lung injury in a murine model of post-viral cMRSA pneumonia.

Vancomycin-Resistant &amp;lt;i&amp;gt;Staphylococcus&amp;lt;/i&amp;gt; aureus Isolates from HIV Positive Patients in Imo State, Nigeria

Vancomycin continues to be an important antimicrobial agent for treating infections caused by <i>Staphylococcus</i> aureus strains that are resistant to oxacillin (MRSA) and other antimicrobial agents. Vancomycin-resistant <i>Staphylococcus aureus</i> (VRSA) isolates were obtained from HIV-positive patients already on HAART treatment but were not admitted in the hospital. Species identification was confirmed by standard biochemical tests and PCR amplification of the 16S rRNA gene. Vancomycin resistance was determined using the Kirby-Bauer diffusion method and confirmed by Brain Heart Infusion (BHI) vancomycin screen agar plate containing 6µg/ml vancomycin. A total of 8 VRSA were identified from the 59 isolates obtained from the patients. Five out of the eight VRSA isolates were resistant to all the antibiotics tested. However, one unusual strain which was resistant to all the antimicrobial agents tested contained no plasmid, <i>Mec</i> A gene and PVL toxin gene. One VRSA isolate contained a large plasmid (~21.2 kb) and four small plasmids of ~5, 2.5, 1.2 and 0.8 kb respectively. The minimum inhibitory concentration (MIC) for vancomycin susceptibility was >15 µg/ml at disk potency of 30µg. The reduced susceptibility of S. <i>aureus</i> strains to vancomycin leaves clinicians with relatively few therapeutic options for treating these infections and therefore emphasizes the importance of prudent use of antibiotics and the use of infection-control precautions to prevent their transmissions.

Molecular epidemiology and antimicrobial susceptibility profiles of methicillin-resistant Staphylococcus aureus blood culture isolates: results of the Quebec Provincial Surveillance Programme.

The objectives of this study were to characterize methicillin-resistant Staphylococcus aureus (MRSA) blood culture isolates and to determine their relative importance in both nosocomial and community-acquired infections. A total of 535 MRSA blood culture isolates were analysed. In vitro susceptibility to 14 agents was determined. The genes nuc, mecA and coding for PVL toxin were identified by PCR. All isolates were characterized by PFGE or spa typing to assess their genomic relationships. Most MRSA isolates were retrieved from nosocomial bloodstream infections (474, 89%) and were of the CMRSA2 genotype. Healthcare-associated (HA)-MRSA bloodstream infections were associated with older age (70-89 years, P = 0·002) and most often secondary to central line infections (P = 0·005). Among MRSA strains associated with community-acquired (CA)-MRSA, 28·8% were isolated in intravenous drug users. CA-MRSA genotypes were more frequently found in young adults (20-39 years, P < 0·0001) with skin/soft tissue as the primary sources of infection (P = 0·006). CMRSA10 genotype was the predominant CA-MRSA strain. All MRSA isolates were susceptible to doxycycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin. Both the presence of the genes coding for PVL toxin (89·8%) and susceptibility to clindamycin (86·5%) were predictive of CA-MRSA genotypes. Whereas in the USA, HA-MRSA have been replaced by USA300 (CMRSA10) clone as the predominant MRSA strain type in positive blood cultures from hospitalized patients, this phenomenon has not been observed in the province of Quebec.

T030, Türkiye’deki Hastanelerden İzole Edilen Metisiline Dirençli Staphylococcus aureus İzolatları Arasında En Yaygın spa Tipidir

Staphylococcus aureus is one of the most frequent agents causing hospital infections. S.aureus has a great ability to adapt itself to variety of conditions and successful clones can be epidemic and even pandemic by its ability spread from one continent to another. The aims of this study were to detect spa types of 397 methicillin-resistant S.aureus (MRSA) strains isolated from 12 centers in different geographical regions of Turkey from 2006 to 2008, and to investigate their clonality by PFGE and MLST typing. Additionally, 91 MRSA from four of those 12 centers isolated during 2011 were also studied for their spa types. PFGE profiles indicated the presence of a major pulsotype, namely pulsotype A with a rate of 91.4% (363/397), followed by pulsotype B (n= 18, 4.5%) and pulsotype C (n= 11, 2.8%). Among isolates tested 363 (91.4%) were SCCmec type III, 30 (7.6%) were SCCmec type IV. Sequence analysis of representative isolates revealed that ST239 (85.1%) was the most common MLST type followed by two MLST types ST737 (4%), and ST97 (2.8%), both SCCmec type IV. Two isolates were ST80 with SCCmec type IV. Of 397 isolates, 338 (85.1%) were t030, followed by t005 (2.5%) and t632 (2%). Among MRSA isolated during 2011, 64 (70.3%) of 91 were t030, 4 (4.4%) were t005, 2 (2.2%) were t015, and 2 (2.2%) were t1094. Among centers the t030 prevalence of 2006-2008 isolates ranged from 59-100%. The highest t030 prevalence was found in Ankara (100%) and lowest in Trabzon (59%) provinces which are located at central and northestern Anatolia, respectively. In Istanbul province, the prevalence of t030 was 94.5% among 2006-2008 isolates which decreased to 55.5% among 2011 isolates. Also a decrease in t030 rates was observed among samples from Konya and Trabzon but not from Aydin. Our results showed that the most common MRSA clone in Turkey is ST 239-SCCmec type III, t030 which persisted during the six years of the study period. Presence of PVL toxin gene was tested by PCR and 5 (3%) isolates found to be positive, of them two were SCCmec Type IV-ST80 and three were SCCmec Type III-ST239. This study is the largest epidemiological survey ever done in Turkey which showed presence of a hospital Turkish clone TR09 (ST239-SCCmecIII-t030) and a community clone TR10 (ST737-SCCmecIV-t005) largely disseminated in Turkey.

Genome sequencing unveils a novel sea enterotoxin-carrying PVL phage in Staphylococcus aureus ST772 from India.

Staphylococcus aureus is a major human pathogen, first recognized as a leading cause of hospital-acquired infections. Community-associated S. aureus (CA-SA) pose a greater threat due to increase in severity of infection and disease among children and healthy adults. CA-SA strains in India are genetically diverse, among which is the sequence type (ST) 772, which has now spread to Australia, Europe and Japan. Towards understanding the genetic characteristics of ST772, we obtained draft genome sequences of five relevant clinical isolates and studied the properties of their PVL-carrying prophages, whose presence is a defining hallmark of CA-SA. We show that this is a novel prophage, which carries the structural genes of the hlb-carrying prophage and includes the sea enterotoxin. This architecture probably emerged early within the ST772 lineage, at least in India. The sea gene, unique to ST772 PVL, despite having promoter sequence characteristics typical of low expression, appears to be highly expressed during early phase of growth in laboratory conditions. We speculate that this might be a consequence of its novel sequence context. The crippled nature of the hlb-converting prophage in ST772 suggests that widespread mobility of the sea enterotoxin might be a selective force behind its ‘transfer’ to the PVL prophage. Wild type ST772 strains induced strong proliferative responses as well as high cytotoxic activity against neutrophils, likely mediated by superantigen SEA and the PVL toxin respectively. Both proliferation and cytotoxicity were markedly reduced in a cured ST772 strain indicating the impact of the phage on virulence. The presence of SEA alongside the genes for the immune system-modulating PVL toxin may contribute to the success and virulence of ST772.

The first case of fatal pneumonia caused by Panton–Valentine leukocidin-producing Staphylococcus aureus in an infant in the Czech Republic

Panton-Valentine leukocidin-producing strains of Staphylococcus aureus can cause severe skin and soft tissue infections and necrotizing pneumonia with a high mortality rate. This is a report on the first case of fatal pneumonia with mediastinitis in an infant in the Czech Republic. The causative agent was a methicillin-susceptible S. aureus strain with pronounced production of the PVL toxin and hyperproduction of enterotoxin A.

Distribution of Staphylococcus aureus strains colonized in healthy community population and molecular epidemiological characteristics for MRSA strains

To investigate the nasal colonization of Staphylococcus (S.) aureus strains among medical university students in Shenyang and to study the molecular epidemiological characteristics of methicillin resistant S. aureus (MRSA) strains. Sterilized nasal swabs were used to collect nasal bacteria from both nares of the students. Nasal specimens were further identified as S. aureus strains, sensitive or resistant to methicillin through a series of tests. Molecular related methods including staphylococcal cassette chromosome mec (SCCmec) typing, pulsed- field gel electrophoresis (PFGE), coagulase isotyping and minimum inhibitory concentration (MIC) determination etc. were used to characterize the isolates. Prevalence of the panton-valentine leukocidin (pvl) genes (lukS and F-PV) among the isolates was also assessed. Staphylococci were found in 488 specimens from 977 participants through the surveillance program, conducted in 2009. Of the 488 specimens being tested, 364 were identified as coagulase-negative staphylococci (CoNS) and 124 as S. aureus. MRSA strain among the S. aureus isolates was accounted for 3.4%. In the surveillance program conducted in 2010, staphylococci grew in 310 specimens from 657 participants. Of the 310 specimens tested, 195 were identified as CoNS and 115 as S. aureus. The percentage of MRSA strains among the S. aureus isolates was 7.7%. In total, 239 students carried S. aureus, and the percentage of MRSA carriers among the total specimens tested in this study was 5.1%. Most of the MRSA strains could be classified into one of the five types of SCCmec elements. Type IV a SCCmec strains were most frequent seen overall (10 isolates). A total of 11 pulsotype were identified among the MRSA strains and were classified into 7 major groups (A to G) by the mutual correlations of their banding patterns. Ten MRSA strains were identified as pvl positive strains. An MRSA clone (IV a SCCmec pulsotype A) carrying pvl toxin gene was found to be prevalent in the nares of the healthy university students.

Lethal Necrotizing Pneumonia Caused by an ST398Staphylococcus aureusStrain

To the Editor: The prevalent colonization of livestock with methicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 398 in many countries is a cause for consternation. However, understanding of the emergence of these organisms and their public health implications is embryonic. The perceptions that all MRSA found in livestock are of ST398 lineage or that livestock are the only reservoirs of ST398 oversimplify a complex epidemiology, therefore, prudence is required when attributing human infections with S. aureus ST398 to livestock reservoirs. The fatal infection of a young girl with ST398 methicillin-susceptible S. aureus (MSSA) is tragic (1). However, the conclusion by the authors that “the spread of S. aureus ST398 among livestock is a matter of increasing concern because strains of this sequence type were able to acquire PVL [Panton-Valentine leukocidin] genes” is misleading. The authors report no history of livestock exposure and the spa type reported (t571) is relatively rare among livestock isolates (2,3). The isolate from the fatal case was tetracycline-susceptible and positive for PVL toxin, while livestock ST398 isolates have been almost uniformly tetracycline resistant and PVL negative. Notably, spa type t571 ST398 MSSA was detected in 9 families from the Dominican Republic living in Manhattan, New York, without contact with livestock (4). Furthermore, t571 was the only spa type of MSSA identified in a study in the Netherlands of ST398 isolates, including 3 independent cases of nosocomial bacteremia in Rotterdam with no apparent livestock contact (5). spa type t571 was the predominant (11%) MSSA type in patients at a Beijing, China, hospital (6). More recently, a study of t571 MSSA strains from cases of bloodstream infections in France determined that the isolates differed from pig-borne strains and shared similarities with strains from humans in China and virulent USA300 strains (7). These observations concur with a hypothesis that ST398 strains of diverse genotype and geographic origin may also be epidemiologically distinct (8), and livestock contact is a notably inconsistent feature of invasive ST398 infections (5,7–10). The possibility that variants of the ST398 lineage may persist in human populations without livestock contact should not be dismissed. The incidence and severity of clinical infections with ST398 S. aureus in livestock workers as yet have been minimal. Understanding the public health implications of ST398 S. aureus requires systematic investigation of their epidemiology in animals and humans. Human clinical cases of ST398 S. aureus infection should not be indiscriminately attributed to livestock, particularly if isolates are genotypically dissimilar to those occurring commonly in animals.

Panton–Valentine leukocidin Staphylococcus aureus osteomyelitis of the adult tibia – a case report

Panton-Valentine leukocidin toxin producing Staphylococcus aureus (PVLSA) is known to be responsible for recurrent soft tissue infections and more serious invasive infections including necrotising pneumonia, pyomyositis, and osteomyelitis. Most reported cases involving musculoskeletal infection in adults are associated with methicillin-resistant S. aureus (MRSA) PVL-producing strains. We present the case of an adult male with PVL toxin-producing methicillin-sensitive S. aureus (MSSA) osteomyelitis of the tibia which has not previously been described in adults and highlight issues of recognition, treatment, and surgical management of PVLSA osteomyelitis.

A brief review of Panton-Valentine leukocidin producing staphylococcal infections in the intensive therapy unit

Panton-Valentine leukocidin toxin has been known about for many years and its production by Staphylococcus aureus in infections is associated with invasive necrotising disease of several systems including skin and soft tissue, and pneumonia. Necrotising pneumonia is associated with high mortality despite provision of antimicrobials and affects predominately younger aged people. A combination of antimicrobial therapy including an agent which acts to inhibit bacterial protein synthesis (such as clindamycin, linezolid, or rifampicin) is the mainstay of therapy with intravenous immunoglobulin, a potentially useful adjunct. Contact screening and public health input is essential in preventing further cases and recolonisation. When PVL toxin producing staphylococcal infection is suspected, close liaison with medical microbiology is paramount to enable optimal treatment and suitable specimens to be sent to the reference laboratory for confirmation.

Transmission of methicillin-resistant Staphylococcus aureus strains between different kinds of pig farms

The main objective of the present study was to investigate if different kinds of pig farms, like farrowing farms and rearing farms, play a role in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) to Dutch finishing farms. Twelve farrowing farms, 11 finishing farms, 6 farrow-to finish farms, 1 rearing farm and 1 centre for artificial insemination were included. Screening of 310 pigs from these 31 farms showed 35 pigs (11%) to carry MRSA in their nares. On 7 of the 31 (23%) investigated farms colonized pigs were found, including 3 finishing farms, 3 farrowing farms and 1 farrow-to-finish farm. The use of standard antimicrobial medication of the pigs seemed to be a risk factor for MRSA carriage. Screening of the pigs on six farms supplying pigs for the MRSA positive farms revealed that the pigs on all but one farm were MRSA positive. Genotyping revealed that all MRSA strains were non-typeable by PFGE using the SmaI restriction enzyme and had multilocus sequence type (MLST) ST398. Different spa-types were found including t011, t108, t567, t899 and t1939, but the spa-types on epidemiologically related farms were identical indicating that MRSA are transmitted between farms through the purchase of colonized pigs. Two SCC mec types were found among the MRSA: type IV and type V. SCC mec type V was predominant. On two farms MRSA isolates with ST398, the same spa-type but with different SCC mec types (IV and V) were found, suggesting that different SCC mec elements have been inserted into MSSA with the same genotype. All MRSA strains were resistant to tetracycline, but additional resistances to erythromycin, lincomycin, kanamycin and gentamicin were also found. All MRSA isolates were negative for the exfoliative toxin genes ( eta and etb), PVL toxin genes ( lukF and lukS), toxic shock syndrome gene ( tst-1), and the leukotoxin genes ( lukE, lukD, lukM, lukF′).

Staph Vaccine Proves Effective in Mice; Role of PVL Toxin Downgraded

Staph Vaccine Proves Effective in Mice; Role of PVL Toxin Downgraded

Community-acquired MRSA and pig-farming

BackgroundSporadic cases of CA-MRSA in persons without risk-factors for MRSA carriage are increasing.Case presentationWe report a MRSA cluster among family members of a pig-farmer, his co-workers and his pigs. Initially a young mother was seen with mastitis due to MRSA. Six months later her baby daughter was admitted to the hospital with pneumococcal otitis. After staying five days in hospital, the baby was found to be MRSA positive. At that point it was decided to look for a possible source, such as other family members and house-hold animals, including pigs on the farm, since those were reported as a possible source of MRSA earlier.Swabs were taken from the throat and nares of family members and co-workers. A veterinarian obtained swabs from the nares, throat and perineum of 10 pigs. Swabs were cultured following a national protocol to detect MRSA that included the use of an enrichment broth. Animal and human strains were characterized by PFGE, spa-typing, MLST analysis, SSCmec, AGR typing, and the detection for PVL, LukM, and TSST toxin genes.Three family members, three co-workers, and 8 of the 10 pigs were MRSA positive. With the exception of the initial case (the mother) all persons were solely colonized, with no signs of clinical infections.After digestion with SmaI, none of the strains showed any bands using PFGE. All isolates belonged to spa type t108 and ST398.Conclusion1. This report clearly shows clonal spread and transmission between humans and pigs in the Netherlands. 2. MLST sequence type 398 might be of international importance as pig-MRSA, since this type was shown earlier to be present in epidemiologically unrelated French pigs and pig-farmers. 3. Research is needed to evaluate whether this is a local problem or a new source of MRSA, that puts the until now successful Search and Destroy policy of the Netherlands at risk.