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Background: Methicillin-resistant Staphylococcus aureus (MRSA) can cause serious infections not only in hospitals but also in the community. The present study was aimed to characterize drug resistance and virulence determinants of community-associated (CA) MRSA isolate compared with healthcare-associated (HA) MRSA. Materials and Methods: A total of 44 patients with HA-MRSA and 11 patients with CA-MRSA infection (median age, 72 years) were included. The clinical isolates of MRSA were subjected to molecular analysis of virulence genes and drug susceptibility testing. Results: Panton-Valentine leucocidin (PVL) exotoxin and toxic shock syndrome toxin (TSST) genes were disproportionately distributed between CA- and HA-isolates. PVL genes were more likely to be found among CA-isolates (36.4%) than HA-isolates (18.2). TSST genes were identified in only 2 CA-MRSA isolates tested (18.2%) compared with 9 HA-isolates (20.5%). Exfoliative toxin- b gene was negative in all isolates, however, one HA-isolate was positive for exfoliative toxin-a. mec-A gene was present in all clinical isolates. CA-isolates were more likely to be susceptible to trimethoprim-sulfamethoxazole and vancomycin compared with HA-isolates. Vancomycin-intermediate resistance was found in 2 HA-isolates. All clinical isolates were also resistant to clindamycin. Conclusions: CA- and HA- MRSA isolates are epidemiologically and microbiologically distinct. Thus, the strategies to prevent and treat these infections would be different. Patients with CA- and HA-MRSA infections should be treated effectively and receive follow-up evaluation to ensure the resolution of their infection. Surveillance studies should be conducted to determine the extent of CA- and HA-MRSA dissemination in Iran.

Three hundred and sixty different samples were collected from different sources, including wound, burn, nasal, and oral swabs from several hospitals in Baghdad. A number of 150 (53%) Staphylococcus aureus samples were isolated and identified among a total of 283 samples. Then, the spread of the Toxic Shock Syndrome Toxin-1 gene (tsst-1) was investigated in β-lactamase resistant S. aureus. According to the source of samples, the distribution of S. aureus isolates was found to be significantly higher (p < 0.01) in wound samples as compared to other sources. According to the age, a highly significant distribution (p < 0.01) was recorded in the age group of 15-30 years, whereas gender comparison showed no statistically significant differences. All the isolates were subjected to susceptibility test against eight β-Lactam antibiotics by using the disc diffusion method. The antimicrobial susceptibility test showed that S. aureus had maximum resistance percentage to Carbenicillin (97.3%), while the lowest resistance rate was against Meropenem, with a sensitivity rate of up to 82%. In addition, 144 (96%) out of the 150 S. aureus isolates have multiple drug resistance (MDR). All the isolates were subjected to polymerase chain reaction to amplify tsst-1 toxin gene. A number of 70 isolates (46.7%) were found to be positive for tsst-1 gene. The results showed no significant correlation between tsst-1 gene with the individual antibiotic resistance and the multi-drug resistance patterns of the isolates (p = 0.226).

Methicillin-resistant Staphylococcus aureus (MRSA) is a widespread pathogen that could cause different illnesses in both human and animals. Presence of MRSA in animals raises concerns of their capacity to act as reservoirs, particularly in wild animals. This study aimed to characterize the resistance and virulence patterns of S.&nbsp, aureus strains isolated from bat guano in Algeria. From March to May 2016, 98 bat guano samples from Aokas’s cave (Bejaia, Algeria) were collected. Swabs were taken for microbiological studies. Isolates were identified by Vitek® MS system, and antibiotic susceptibility was determined by disk diffusion method. The clonal origin, virulence and antibiotic resistance profiles of S. aureus isolates were characterized by whole genome sequencing. Eleven S.&nbsp, aureus strains were obtained from the 98 guano samples. Seven isolates were sensitive to all antibiotics tested and four (36.3%) were resistant to penicillin G, cefoxitin and fusidic acid. The four MRSA isolates were assigned to the sequence type ST149 and related to spa type t010. These isolates harbored a SCCmecIV element and the fusidic acid resistance element Q6GD50 (fusC). They carried different virulence genes including several enterotoxins (sea, egc enterotoxin locus, sec, sel), and the toxic shock syndrome toxin (tst). Our results highlight that bat guano may constitute an important reservoir of MRSA strains.

Ο ανθεκτικός στη μεθικιλλίνη Staphylococcus aureus (MRSA) αποτελεί σημαντικό αίτιο ενδονοσοκομειακών λοιμώξεων (HA-MRSA) καθώς επίσης και της κοινότητας (CA-MRSA). Οι σοβαρές λοιμώξεις από MRSA έχουν συσχετιστεί με τον λοιμογόνο παράγοντα Panton-Valentine leukocidin, (PVL). Μέρος αυτής της μελέτης ήταν να διερευνήσει τα πρότυπα ευαισθησίας, την παρουσία γονιδίων τοξινών συμπεριλαμβανομένης και της PVL και την κλωνικότητα μεταξύ MRSA που συλλέχθηκαν από ασθενείς στην Ελλάδα κατά τη διάρκεια μιας περιόδου έξι ετών. Συνολικά, 1678 MRSA συλλέχθηκαν από τον Ιανουάριο του 2007 μέχρι το Δεκέμβριο του 2012 από δύο διαφορετικά νοσοκομεία στη Δυτική Ελλάδα και ταυτοποιήθηκαν με βάση την ανίχνευση των γονιδίων nuc και mecA με PCR. Η αντοχή στα αντιβιοτικά πραγματοποιήθηκε με τη μέθοδο διάχυσης των δίσκων και το E-test. Η παρουσία των γονιδίων που κωδικοποιούν την τοξίνη TSST-1, την PVL και ορισμένα γονίδια των εντεροτοξινών ελέγχθηκε με PCR. Τα γονοτυπικά χαρακτηριστικά των στελεχών αναλύθηκαν με την ταυτοποίηση των τύπων SCCmec και agr. Η κλωνικότητα καθορίστηκε μέσω PFGE και MLST. Η πλειοψηφία των PVL-θετικών MRSA ανήκε στον ST80-IV κλώνο ο οποίος διεσπάρη στην κοινότητα αλλά και τα νοσοκομεία. CA-MRSA απομονώθηκαν κυρίως από SSTIs, ενώ HA-MRSA συνδέθηκαν με χειρουργικές λοιμώξεις και μολύνσεις τραυμάτων. Κατά την περίοδο 2007-2012, ο ST80-IV έχει κυριαρχήσει στην Ελλάδα και έχει περιορίσει με επιτυχία την παρουσία άλλων PVL-θετικών κλώνων. Το δεύτερο μέρος της παρούσας μελέτης επικεντρώνεται στην μελέτη διασποράς των S. aureus και MRSA μεταξύ των ζώων συντροφιάς και του κτηνιατρικού προσωπικού (ΚΠ) στην Βόρεια Ελλάδα. Τα μοριακά χαρακτηριστικά των στελεχών αξιολογήθηκαν, προκειμένου να εκτιμηθεί εάν υφίσταται μετάδοση του S. aureus. Δείγματα (224) που αποίκισαν και μόλυναν 102 ζώα (92 σκυλιά, 10 γάτες) και 18 ΚΠ, συλλέχθηκαν κατά τη διάρκεια του 2012 και του 2013. Η ευαισθησία στα αντιβιοτικά διερευνήθηκε με τη μέθοδο διάχυσης των δίσκων και E-test. Τα mecA, mecC, tst και lukF/lukS-PV γονίδια μελετήθηκαν με PCRs. Οι γονότυποι προσδιορίστηκαν με την ταυτοποίηση των τύπων MLST, SCCmec, agr, spa και PFGE. Το ποσοστό απομόνωσης S. aureus μεταξύ των κατοικίδιων ζώων και του ΚΠ ήταν 36.3% (37/102) και 38.9% (7/18), αντίστοιχα. Τα νεώτερα ζώα συντροφιάς, όσοι ζουν σε αγροτικές περιοχές, νοσούσαν κατά την εισαγωγή ή ήταν ήδη αποικισμένοι με CNS έδειξαν στατιστικά σημαντικά αυξημένο κίνδυνο για προσβολή από S. aureus (p

Staphylococcus aureus is one of the predominant bacteria isolated from skin and soft tissue infections and a common cause of bloodstream infections. The aim of this study was to compare the rate of resistance to various antimicrobial agents and virulence patterns in a total of 200 S. aureus strains isolated from patients with bacteremia and chronic wounds. Disk diffusion assay and in the case of vancomycin and teicoplanin-microdilution assay, were performed to study the antimicrobial susceptibility of the isolates. The prevalence of genes encoding six enterotoxins, two exfoliative toxins, the Panton–Valentine leukocidin and the toxic shock syndrome toxin was determined by PCR. Of the 100 blood strains tested, the highest percentage (85.0%, 31.0%, and 29.0%) were resistant to benzylpenicillin, erythromycin and clindamycin, respectively. Out of the 100 chronic wound strains, the highest percentage (86.0%, 32.0%, 31.0%, 31.0%, 30.0%, and 29.0%) were confirmed as resistant to benzylpenicillin, tobramycin, amikacin, norfloxacin, erythromycin, and clindamycin, respectively. A significantly higher prevalence of resistance to amikacin, gentamicin, and tobramycin was noted in strains obtained from chronic wounds. Moreover, a significant difference in the distribution of sea and sei genes was found. These genes were detected in 6.0%, 46.0% of blood strains and in 19.0%, and 61.0% of wound strains, respectively. Our results suggest that S. aureus strains obtained from chronic wounds seem to be more often resistant to antibiotics and harbor more virulence genes compared to strains isolated from blood.

The aim of the present study was to identify predictors of fatality among patients with S. aureus infections requiring hospitalization. Cases hospitalized with S. aureus infections at the University General Hospital of Patras, Greece, during a 4-year period (2013-2016) were studied. mecA, lukS/lukF-PV (Panton-Valentine leukocidin, PVL), tst (toxic shock syndrome toxin), fnbA (fibronectin-binding protein A), eta, and etb (epidermolytic toxins) genes' carriage was detected by PCR in 149 selected patients. Among 464 patients, 346 were included (118 with missing data). Primary bacteremia predominated (44.2%), followed by lower respiratory tract infections (13.6%), deep seated infections (9.8%), osteoarticular (9.5%), and catheter-related bloodstream infections (6.1%). Methicillin-resistant S. aureus (MRSA) represented 33.8% of infections and were less likely to receive appropriate empiric treatment (79.5% versus 97.4%; P < 0.001). Thirty-day fatality was 14.5%. Multivariate analysis revealed that development of septic shock, Charlson Comorbidity Index, lower respiratory tract infection, bacteremia (primary or secondary), MRSA, and CRP was significantly associated with fatality. Appropriate empiric treatment was a predictor of good prognosis. Thirty-two out of 149 S. aureus (21.5%) carried lukS/lukF-PV genes, whereas, 14 (9.4%), 133 (78.7%), four (2.7%), and one (0.7%) carried tst, fnbA, eta, and etb genes, respectively. No difference was found among toxin genes' presence and mortality. PVL was significantly more frequently found among MRSA as compared to MSSA (45.1% versus 9.2%; P < 0.001). MRSA represented one third of the infections requiring hospitalization and were independently associated with fatality, probably since were more likely to receive inappropriate antibiotic treatment as compared to MSSA.

Intramammary infections are a serious problem in dairy sheep farming, and Staphylococcus epidermidis is one of the main etiological agents of ovine mastitis. In this work, 199 S. epidermidis isolates collected in Sardinia (Italy) from sheep milk samples and used for the preparation of inactivated autogenous vaccines were characterized with phenotypic and genotypic methods. The potential for biofilm production was evaluated phenotypically by assessing colony characteristics on Congo Red Agar (CRA), and genotypically by PCR for i) the icaA/D genes coding the polysaccharide intercellular adhesin (PIA) and ii) for the bhp, aap and embp genes coding biofilm accumulation proteins. Isolates were also investigated by PCR for the presence of autolysins (atlE and aae genes), microbial surface components recognizing adhesive matrix molecules (MSCRAMMs, sdrG and sdrF genes), enterotoxins (sea, seb, sec, sed and see genes), and the toxic shock syndrome toxin (tsst genes). In addition, the staphylococcal accessory gene regulator (agr), the most important locus responsible for the regulation of virulence factors, was characterized for the first time. As a result, only two isolates showed biofilm production on CRA and harbored the icaA/D genes. Four isolates, phenotypically classified as non-biofilm producers, possessed the icaA/D genes (n = 3) or only the icaA gene (n = 1). All isolates harbored the atlE, aae, embp and sdrG genes, but none harbored the genes encoding enterotoxins and tsst. Most isolates belonged to the agr-3se group (56.3%), followed by agr-1se (41.2%) and agr-2se (2.5%). All six isolates that harbored ica genes belonged to agr-1se. In conclusion, this study provides a detailed characterization of the putative virulence genes present in S. epidermidis strains circulating in Sardinian sheep. Because of their role in ovine mastitis pathogenesis, these might represent valuable candidates for vaccine development.

Background Staphylococcus aureus is a common pathogen causing hospital acquired infections (HAIs) in neonates. In this study, the epidemiology of methicillin-resistant S. aureus (MRSA) colonization and infections in a 30-bed, level III university-affiliated neonatal intensive care unit (NICU) located in a children's hospital was retrospectively investigated for the period 2014–2018. Methods Genes encoding Panton-Valentine Leukocidin (lukS/lukF-PV, PVL), toxic shock syndrome toxin (tst), exfoliative toxins (eta, etb), and the resistance genes mecA, mecC and fusB, were defined in 46 representative strains by PCRs. Relatedness of strains was assessed by MLST. Results Of 1538 neonates, 77 (5%) had a positive culture for MRSA (23/77 were NICU-acquired and 54/77 imported cases). Four MRSA bacteremias occurred. Most isolates were multi-resistant. One major clone was identified, ST225, among 40 tested neonatal strains (23/40, 58%). Of these, 14/23 were imported from the same maternity hospital (MH). Another clone, ST217, was predominant (4/6) among health care workers (HCWs), found colonized. Four isolates classified as ST80 were PVL-positive. Additional four strains carried tst (10%), belonging to ST30 and ST225 (two strains each), and two etb. The implicated MH was notified for the problem, decolonization treatment was successfully performed in HCWs and neonates. Strengthening of infection control measures with emphasis on hand hygiene was applied. Conclusions Uncovering reservoirs for on-going MRSA transmission in NICUs has proved challenging. Well known nosocomial MRSA clones are being constantly introduced and transmitted via MHs and HCWs. Effective infection prevention and control requires constant vigilance.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a common causative agent of pneumonia; however, the detailed mechanism underlying severe MRSA pneumonia, including association with oral hygiene or periodontitis, remains poorly characterized. In this study, we examined the pathogenic effect of Prevotella intermedia, a major periodontopathic pathogen, on MRSA pneumonia. Methods: The pathogenic effect of the supernatant of P. intermedia (Pi Sup) was investigated in a murine MRSA pneumonia model, using several clinical strains; whereas the bactericidal activity of polymorphonuclear leukocytes (PMNs) was investigated in vitro. The effect of Pi Sup on messenger RNA (mRNA) expression of the toxin/quorum sensing system (rnaIII) was investigated by quantitative reverse transcription PCR both in vitro and in vivo. Results: Mice infected by hospital-acquired MRSA (HA-MRSA) with Pi Sup exhibited a significantly lower survival rate, higher bacterial loads in the lungs, and higher α-hemolysin (hla) expression in the lungs, than those without Pi Sup. A similar effect of Pi Sup was not observed with MRSA strains producing Panton-Valentine leucocidin (PVL) or toxic shock syndrome toxin (TSST). In vitro, Pi Sup suppressed bactericidal activity of PMNs against the HA-MRSA strain. HA-MRSA was the clinical strain with the highest ability to proliferate in the lungs and was accompanied by time-dependent up-regulation of rnaIII and hla. Conclusions: Our results provide novel evidence that the product of P. intermedia exerts a pathogenic effect on MRSA pneumonia, in particular with a strain exhibiting strong proliferation in the lower airway tract. Moreover, our results indicate that P. intermedia affects MRSA toxin expression via quorum sensing in a strain-dependent fashion, which might be important for understanding the pathogenesis of severe MRSA pneumonia.

In this study one handered and five samples were collected from skin infection in hospital Diwaniyah Dermatology Consultancy in Al-Diwaniyah governorate. from December 2018 to April 2019. All samples were cultured and Identified by using phenotyping tests. The results revealed that 41 isolates were Staph. spp. and 30 Isolates out of them Diagnosed Staphylococcus aureus by using (API staph). Virulence factors were explicated by using polymerase chain reaction (PCR) methicillin-resistant staphylococcus aureus ( MRSA ), were identified by detecting (mecA gene), which revealed that all skin infections were MRSA ( 100 % ). Also, toxic shock syndrome toxin ( TSST ) were identified by using PCR to detect ( tst-1 gene 326 bp.), which revealed that 23 isolate were positive out of 30 isolate ( 76.33 % ).

Methicillin-resistant Staphylococcus aureus (MRSA) strains that carry the tst gene are disseminated worldwide with varying regional incidences and different genetic backgrounds. The data on molecular characteristics of these strains is insufficient in Iran. The present study aimed to assess the characteristics and distribution of spa types of tst-positive MRSA strains. We investigated 89 MRSA isolates carrying the tst gene with spa typing, resistance gene detection and in vitro antimicrobial susceptibility. Of the 89 tested isolates, 61 (68.5%) were confirmed as multidrug resistant (MDR). The isolates were distributed across seven clonal complexes (CCs) including CC22 (42.7%), CC8 (28.1%), CC5 (11.2%), CC59 (5.6%), CC30 (4.5%), CC80 (4.5%) and CC15 (3.4%). spa typing identified 11 distinct types, with t223 (16.9%) and t790 (15.7%) being the most prevalent. All high-level mupirocin-resistant strains belonged to t002 (n = 8) and low-level mupirocin-resistant strains belonged to t790 (n = 6) spa types. Fusidic-acid-resistant isolates belonged to t437 (n = 3). iMLSB phenotype was observed in t005 (6.7%), t002 (5.6%), t790 (3.4%), and t030, t044 and t084 (each 2.2%). It was found that in the tst-carrying MRSA strains, there were genetic diversities with a majority of the t223 spa type. Indeed, there is a necessity for more constructive surveillance/infection control strategies to address the prevalence and prevention of the emerging spa types.

Haemophilus influenzae was the main causative organism for acute epiglottitis in the pre-Haemophilus influenzae type b (Hib) vaccine era. However, with current widespread Hib vaccination, the causative organisms may have changed. Here, we report the case of a healthy infant with acute epiglottitis caused by community-acquired methicillin-resistant Staphylococcus aureus (MRSA). The patient was a healthy 17-day-old male infant without a family history of immunodeficiency syndrome. He had not been started on any vaccines. On the third day of illness, he was diagnosed with acute pharyngitis with exudation on the back of the larynx. Although treatment using cefotaxime was initiated, he showed stridor, difficulty in pronunciation, and cyanosis upon crying on the fourth day. On the fifth day, he was diagnosed with acute epiglottitis by laryngoscopy, which showed a downward spread of the exudation and laryngeal edema. He was intubated and started on artificial respiration. Due to the detection of MRSA from a pharyngeal swab culture, he was treated with vancomycin. His fever disappeared on the first day after admission, and he was extubated on the eighth day after admission. MRSA genome analysis of the patient sample revealed negative Panton-Valentine leukocidin, positive toxic shock syndrome toxin 1, and type IV clone of staphylococcal cassette chromosome mec. This is a first case of acute epiglottitis caused by MRSA with a Panton-Valentine leukocidin-negative and toxic shock syndrome toxin 1-positive staphylococcal cassette chromosome mec type IV clone, which is known as a community-acquired MRSA in Japan. Community-acquired MRSA may be considered a causative organism for acute epiglottitis in the post-Hib vaccine era.

Foods may potentially serve as vehicles for the transmission of antimicrobial-resistant variants of Staphylococcus aureus that are important in a human clinical context. Further, retail food products can be a cause of staphylococcal food poisoning. For these reasons and to account for source attribution and risk assessment, detailed information on the population structure, resistance, and virulence profiles of S. aureus originating from retail food products is necessary. In the current study, whole-genome sequences from 88 S. aureus isolates were subjected to bioinformatics analyses in relation to sequence types, antimicrobial resistance, and virulence profiles. The sequence types (ST) identified belonged to 13 clonal complexes (CC) with CC5 and CC398 being the most common. CC398 was identified as the dominant clone (n = 31). CC5 was identified as of avian origin, with the presence of φAVβ prophage genes (n = 13). In total, 39.8% of the isolates contained multiple resistance genes, and methicillin-resistant Staphylococcus aureus (MRSA) isolates were found in CC8, CC9, and CC398. Genes conferring resistance to the antimicrobial classes of β-lactams, tetracycline, and erythromycin were detected in this study, all of which are commonly used in Danish livestock production. The tst gene encoding the toxic shock syndrome toxin was for the first time identified in ST398 isolates, probably as a result of a single acquisition of a SaPI-like element. The sushi-CC398 isolates carrying the scn gene likely originated from a human reservoir, while the other isolates originated from livestock. Taken together, our results show that both human and animal reservoirs contribute to contamination in food products and that retail foods may serve as a vehicle of S. aureus between livestock and humans. Published version

Antimicrobial resistance of Staphylococcus aureus is a major problem in human and veterinary medicine. The aim of this study was to characterise S. aureus isolates from wild and zoo animals mainly associated with bacterial infections. In total, 23 S. aureus isolates, including nine from wild animals and 14 from zoo animals, were obtained during routine diagnostics. All isolates were subjected to multilocus sequence typing (MLST), spa typing, macrorestriction analysis with subsequent SmaI pulsed-field gelelectrophoresis (PFGE), antimicrobial susceptibility testing and S. aureus-specific DNA-microarray analysis. Resistant isolates were also tested for their respective resistance genes by PCR. Isolates from zoo animals and wildlife showed a high diversity of MLST types, spa types and PFGE patterns. Nineteen different spa types were identified, including three novel types and 16 main macrorestriction patterns. Only few isolates were resistant to members of four classes of antimicrobial agents and harboured the respective resistance genes (β-lactams [blaZ, mecA, mecC], tetracyclines [tet(K), tet(L)] and chloramphenicol [catpC221]) or mutations (fluoroquinolones). The DNA microarray analysis identified one isolate from a zoo animal harbouring the toxic shock syndrome toxin gene tst1. Moreover, several enterotoxin genes were detected in five S. aureus isolates. All isolates were negative for Panton-Valentine leukocidin (PVL) genes, but the animal-associated leukocidin genes lukM/lukF-P83 were found in three isolates from two animals.

The aim of this study was to investigate the toxin gene profile and antimicrobial resistance of Staphylococcus aureus isolates from raw chicken in the People's Republic of China. In total, 289 S. aureus isolates were characterized by antimicrobial susceptibility testing, and genes encoding enterotoxins, exfoliative toxins, Panton-Valentine leukocidin, and toxic shock syndrome toxin were revealed by PCR. Overall, 46.0% of the isolates were positive for one or more toxin genes. A high proportion of toxin genes were pvl (26.6%), followed by sej (12.5%), sea (9.0%), seh (8.3%), seb (6.9%), sec (6.9%), sed (4.8%), sei (3.1%), and see (2.4%). None of the isolates harbored seg, tsst-1, or exfoliative toxin genes. In total, 29 toxin gene profiles were obtained, and pvl (10.7%) was the most frequent genotype, followed by sea (5.9%), seb (4.8%), and sej (4.2%). Furthermore, 99.7% of the strains were resistant to at least one of the tested antimicrobial agents, and 87.2% of them displayed multidrug resistance. Resistance was most frequently observed to trimethoprim-sulfamethoxazole and erythromycin (86.2% for each), followed by tetracycline (69.9%), amoxicillin-clavulanic acid (45.0%), and ampicillin (42.6%). None of the strains were resistant to vancomycin. This study indicates that S. aureus isolates from raw chicken harbored multiple toxin genes and exhibited multiple antimicrobial resistance, which represents a potential health hazard for consumers.

Aims To perform a phenotypic and genotypic characterization of 258 S. aureus isolates from clinical ovine mastitis and used for the preparation of inactivated autogenous vaccines. Methods and Results The potential for biofilm production was determined by phenotypic test of Congo Red Agar (CRA) and by PCR for the detection of icaA/D genes. Isolates were also screened by PCR for the presence of enterotoxins (sea, seb, sec, sed and see), toxic shock syndrome toxin (tsst), leukotoxins (lukD-E, lukM and lukPV83), haemolysins (hly-β and hly-γ), autolysin (atlA) genes and encoding microbial surface components recognized adhesive matrix molecules (MSCRAMMs: clfA, clfB, fnbA, fnbB, bbp, cna, eno, fib, epbs, sdrC, sdrD and SdrE). None of the 258 isolates showed biofilm-forming ability on Congo red agar (CRA) and harboured icaA/D genes. The most frequent pyrogenic toxin superantigen genes amplified were sec plus tsst-1, which were found strictly in combination in 71.3% of the S. aureus isolates tested. None of the isolates harbored the genes encoding sea and see. Of the 258 isolates tested, 159 (61.6%) possessed all lukD-E/lukM/lukPV83 genes, 123 (47.7%) harboured both hly-β/hly-γ genes, whereas almost all (97.3%) were PCR positive for atlA gene. With respect to adhesion determinants, 179 (69.4%) isolates presented simultaneously four genes (fnbA, fib, clfA and clfB) for fibronectin and fibrinogen-binding proteins. Conclusions In this search, several putative virulence determinants have been identified in ovine S. aureus isolates collected in Sardinia. Significance and Impact of the Study Some of the putative virulence determinants could be considered as components of a vaccine because of their role in ovine mastitis pathogenesis. This article is protected by copyright. All rights reserved.

This study was performed to evaluate the clinical impacts of putative risk factors in patients with Staphylococcus aureus bloodstream infections (BSIs) through a prospective, multicenter, observational study. All 567 patients with S. aureus BSIs that occurred during a 1-year period in six general hospitals were included in this study. Host- and pathogen-related variables were investigated to determine risk factors for the early mortality of patients with S. aureus BSIs. The all-cause mortality rate was 15.0% (85/567) during the 4-week follow-up period from the initial blood culture, and 76.5% (65/85) of the mortality cases occurred within the first 2 weeks. One-quarter (26.8%, 152/567) of the S. aureus blood isolates carried the tst-1 gene, and most (86.2%, 131/152) of them were identified to be clonal complex 5 agr type 2 methicillin-resistant S. aureus (MRSA) strains harboring staphylococcal cassette chromosome mec type II, belonging to the New York/Japan epidemic clone. A multivariable logistic regression showed that the tst-1 positivity of the causative S. aureus isolates was associated with an increased 2-week mortality rate both in patients with S. aureus BSIs (adjusted odds ratio [aOR], 1.62; 95% confidence interval [CI], 0.90 to 2.88) and in patients with MRSA BSIs (aOR, 2.61; 95% CI, 1.19 to 6.03). Two host-related factors, an increased Pitt bacteremia score and advanced age, as well as a pathogen-related factor, carriage of tst-1 by causative MRSA isolates, were risk factors for 2-week mortality in patients with BSIs. Careful management of patients with BSIs caused by the New York/Japan epidemic clone is needed to improve clinical outcomes.

The aim of this work was to assess a novel pseudo-staphylococcal cassette chromosome mec (SCCmec) element in methicillin-resistant Staphylococcus aureus (MRSA) blood isolates. Community-associated MRSA E16SA093 and healthcare-associated MRSA F17SA003 isolates were recovered from the blood specimens of patients with S. aureus bacteremia in 2016 and in 2017, respectively. Antimicrobial susceptibility was determined via the disk diffusion method, and SCCmec typing was conducted by multiplex polymerase chain reaction. Whole genome sequencing was carried out by single molecule real-time long-read sequencing. Both isolates belonged to sequence type 72 and agr-type I, and they were negative for Panton-Valentine leukocidin and toxic shock syndrome toxin. The spa-types of E16SA093 and F17SA003 were t324 and t2460, respectively. They had a SCCmec IV-like element devoid of the cassette chromosome recombinase (ccr) gene complex, designated as SCCmecE16SA093. The element was manufactured from SCCmec type IV and the deletion of the ccr gene complex and a 7.0-kb and 31.9-kb portion of each chromosome. The loss of the ccr gene complex results in the mecA gene becoming immobile in MRSA, which would be an adaptive evolutionary mechanism for survival in an antimicrobial-abundant environment. For this reason, the dissemination of this clone should be monitored closely.

Infections by methicillin-resistant Staphylococcus aureus (MRSA) are gradually increasing in the community. In this study, we investigated a total of 162 food samples including 112 ready-to-eat (RTE) foods and 40 processed raw meat and fish samples collected from retail vendors in Dhaka, Bangladesh and determined the occurrence of toxigenic S. aureus and MRSA. Around 22% of samples were positive for S. aureus, RTE foods being more positive (23%) than the processed raw meat/fish samples (18%). Among 35 S. aureus isolates, 74% were resistant to erythromycin, 49% to ciprofloxacin and around 30% to oxacillin and cefoxitin. Around 37% of isolates were resistant to ≥3 classes of antibiotics and 26% of isolates (n = 9) were identified as MRSA. Majority of the isolates were positive for enterotoxin genes (74%), followed by pvl gene (71%), toxic shock syndrome toxin (tsst) gene (17%) and exfoliative toxin genes (11%). Multi locus sequence typing (MLST) of 9 MRSA isolates identified four different types such as ST80 (n = 3), ST6 (n = 2), ST239 (n = 2) and ST361 (n = 2). spa typing of MRSA isolates revealed seven different types including t1198 (n = 2), t315 (n = 2), t037 (n = 1), t275 (n = 1), t304 (n = 1), t8731 (n = 1) and t10546 (n = 1). To our knowledge, this is the first report entailing baseline data on the occurrence of MRSA in RTE foods in Dhaka highlighting a potential public health risk to street food consumers.

Mastitis in ruminants is an important disease with major effects on both the economy and animal welfare. It is caused by major pathogens such as Staphylococcus aureus and minor pathogens such as coagulase-negative staphylococci. The objective of this study was to identify and characterize staphylococci as a cause of sheep mastitis in Algeria. In this study, 123 milk samples were collected directly from the udder of sheep suffering from clinical mastitis in 2 provinces in Algeria. Recovered isolates were identified using MALDI-TOF mass spectrometry. Virulence-associated and antimicrobial resistance genes as well as clonal complexes (CC) of S. aureus were determined using microarray-based analysis. A total of 45 staphylococci isolates were cultivated from sheep milk samples, and 28 S. aureus were identified as methicillin susceptible (62.2%). Seventeen other Staphylococcus isolates of different species were identified using MALDI-TOF mass spectrometry. Subsequent microarray analysis typed the methicillin-susceptible S. aureus to 6 CC: CC8-MSSA, CC97-MSSA, CC130/521-MSSA, CC479-MSSA, CC522-MSSA, and CC705-MSSA. The accessory gene regulator agrIII and the ruminant leukocidin genes lukF-P83 and lukM were found in all isolates of CC130/521, CC479, CC522, and CC705. The toxic shock syndrome toxin gene tst1 was detected exclusively in CC130/521. Additionally, virulence-associated genes (sea, sed, sak, hld, hlgA, edinB, and others) were detected. The presence of antibiotic resistance genes [blaZ, erm(B), and tet(K)] was detected in small numbers of staphylococci. Staphylococci possessing these genes are considered potential hazards for farm animals, farmers, and consumers. Data concerning the prevalence and diversity of staphylococci causing mastitis in sheep from Algeria are lacking. Presented results on different aspects about staphylococci in Algerian sheep populations should at least partially close that gap. However, further extensive studies covering more geographical regions are needed to assess the epidemiological risk.

Menstrual toxic shock syndrome (TSS) is a serious infectious disease associated with vaginal colonization by Staphylococcus aureus producing the exotoxin TSS toxin 1 (TSST-1). We show that menstrual TSS occurs after TSST-1 interaction with an immune costimulatory molecule called CD40 on the surface of vaginal epithelial cells. Other related toxins, where the entire family is called the superantigen family, bind to CD40, but not with a high-enough apparent affinity to cause TSS; thus, TSST-1 is the only exotoxin superantigen associated. Once the epithelial cells become activated by TSST-1, they produce soluble molecules referred to as chemokines, which in turn facilitate TSST-1 activation of T lymphocytes and macrophages to cause the symptoms of TSS. Identification of small-molecule inhibitors of the interaction of TSST-1 with CD40 may be useful so that they may serve as additives to medical devices, such as tampons and menstrual cups, to reduce the incidence of menstrual TSS., Mucosal and skin tissues form barriers to infection by most bacterial pathogens. Staphylococcus aureus causes diseases across these barriers in part dependent on the proinflammatory properties of superantigens. We showed, through use of a CRISPR-Cas9 CD40 knockout, that the superantigens toxic shock syndrome toxin 1 (TSST-1) and staphylococcal enterotoxins (SEs) B and C stimulated chemokine production from human vaginal epithelial cells (HVECs) through human CD40. This response was enhanced by addition of antibodies against CD40 through an unknown mechanism. TSST-1 was better able to stimulate chemokine (IL-8 and MIP-3α) production by HVECs than SEB and SEC, suggesting this is the reason for TSST-1’s exclusive association with menstrual TSS. A mutant of TSST-1, K121A, caused TSS in a rabbit model when administered vaginally but not intravenously, emphasizing the importance of the local vaginal environment. Collectively, our data suggested that superantigens facilitate infections by disruption of mucosal barriers through their binding to CD40, with subsequent expression of chemokines. The chemokines facilitate TSS and possibly other epithelial conditions after attraction of the adaptive immune system to the local environment.

Staphylococcus aureus (S.aureus) is a Gram-positive bacterium that causes many infections and diseases. This pathogen can cause many types of infections such as impetigo, toxic shock syndrome toxin (TSST1), pneumonia, endocarditis, and autoimmune diseases like lupus erythematosus and can infect other healthy individuals. In the pathogenic process, colonization is a main risk factor for invasive diseases. Various factors including the cell wall-associated factors and receptors of the epithelial cells facilitate adhesion and colonization of this pathogen. S. aureus has many enzymes, toxins, and strategies to evade from the immune system either by an enzyme that lyses cellular component or by hiding from the immune system via surface antigens like protein A and second immunoglobulin-binding protein (Sbi). The strategies of this bacterium can be divided into five groups: A: Inhibit neutrophil recruitment B: Inhibit phagocytosis C: Inhibit killing by ROS, D: Neutrophil killing, and E: Resistance to antimicrobial peptide. On the other hand, innate immune system via neutrophils, the most important polymorphonuclear leukocytes, fights against bacterial cells by neutrophil extracellular trap (NET). In this review, we try to explain the role of each factor in immune evasion.

Background Atopic dermatitis (AD) patients are more frequently colonized with Staphylococcus aureus. The aim of this study is to determine the prevalence of community-acquired methicillin-resistant S. aureus (CA-MRSA) colonization in AD patients in a dermatology clinic in Mansoura, Egypt, and to assess the resistance pattern and the superantigen genes among isolated strains. Methods Sixty AD patients were evaluated for the carriage of CA-MRSA in both lesional skin and nose. Antimicrobial susceptibility tests were performed using the disc diffusion method. The detection of mecA gene and superantigen genes, toxic shock syndrome toxin (tsst), and staphylococcal enterotoxin sea-sed were done by PCR. Results Twenty-eight patients (46.7%) were colonized with CA-MRSA. All isolates were sensitive to vancomycin. Only 9.7% of isolates were resistant to ciprofloxacin, while 52.6% of isolates were resistant to fusidic acid and 48.4% were resistant to erythromycin. The predominant toxin gene found in AD patients was tsst that found in 100% of isolates of CA-MRSA, while seb and sed genes found only in 61.2% of the isolates. Conclusion Atopic dermatitis patients were colonized with CA-MRSA. The most common toxin gene in the Egyptian AD patients was tsst. There is no significant association between any of superantigen genes and severity of AD.

Background: Staphylococcal food poisoning is one of the most common food borne diseases. Widespread incidence of antibiotic resistances of Staphylococcus aureus have been reported in the world. The bacterium causes this poising by producing different toxins. Objectives: The aim of this study was to determine the presence of toxic shock syndrome toxin (TSST-1) and methicillin resistance (mecA) producing genes in isolated S. aureus from local cheese in northwest of Iran. Methods: A total of 22 S. aureus samples, already identified by biochemical tests for diagnosis of S. aureus, were isolated from local cheese, and identified as S. aureus with proliferation of thermonuclease species-specific gene (nuc) by PCR method. To determine the frequency of TSST-1 and mecA, genes were tested by PCR method. Results: Of 22 S. aureus isolates, one case (4.54%) contained mecA gene and two cases (9.09%) possessed TSST-1 gene. None of the tested isolates harbored the intended genes simultaneously. Conclusions: The presence of S. aureus isolates in local cheese, which harbor toxic shock syndrome toxin (TSST-1) and methicillin resistance (mecA) genes, show that these isolates have high potential in producing toxic shock syndrome toxin and methicillin resistance; therefore, the use of procedures to reduce the bacterial contamination during the processing of dairy product is required.

The objectives of this study were to characterize Staphylococcus aureus isolated from artisanal and industrialized Minas frescal cheeses, to determine their antimicrobial susceptibility profile as well as the genetic similarity among the isolates. The isolates were also tested for staphylococcal enterotoxin genes and other virulence factors. Fifty-six artisanal raw milk cheeses sold at street fairs and 10 industrialized cheeses commercialized in supermarkets of Goiânia, Goiás, were analyzed. Staphylococcus aureus was confirmed in 19 samples (33.9%) of artisanal cheese by detection of femA gene, in which 29 isolates were obtained. These isolates were submitted to the antimicrobial susceptibility test and classified into 9 different profiles (A-I). Thirteen isolates (44.8) were resistant to penicillin and 3 (10.3) to tetracycline, with 2 (7.4) resistant to both. The multiplex PCR technique was performed to detect virulence genes that code for the production of hemolysins (Hla and Hlb), toxic shock syndrome toxin (TSST-1), exfoliative toxins (ETa and ETb), and staphylococcal enterotoxins [SE; SEA-SEE, SEG-SEJ, SEM-SEO]. All the isolates amplified for the hla gene and 14 (48.3%) for the hlb gene. The seh gene was the most frequently detected (n=11, 37.9%), followed by seo gene (n=3; 10.3%). In one isolate (3.4%), 4 enterotoxins genes were detected, and in another, 6 (3.4%) were detected. The comparison performed by pulsed-field gel electrophoresis of the 29 isolates revealed 18 genotypic profiles, which were grouped into 5 clusters. The genotyping found high genetic similarity among the isolates. Identical isolates were obtained from different samples and one sample showed more than one genetically different isolate. The high prevalence of S. aureus in the Minas Frescal cheese samples, as well as the detection of toxin encoding genes identified in this study, warns of the necessity to reduce the contamination levels in this type of cheese through monitoring and controlling the production and trade of the product.

Staphylococcus aureus is a leading infectious cause of life-threatening disease in humans, yet there is currently no vaccine to combat this bacterium. The pathogenesis of S. aureus is mediated by a diverse array of protein toxins including a large family of secreted pyrogenic superantigens. Neutralization of superantigens, including SEB and TSST-1, has proven to be protective in several animal models of toxic shock and sepsis. We demonstrate, for the first time, that a far more prevalent staphylococcal superantigen, SEK, can also induce lethal shock in mice. Additionally, we describe monoclonal antibodies (mAbs) that inhibit SEK-induced mitogenicity as well as protect against SEK-induced lethality, and enhance survival from S. aureus septicemia in murine models. MAb-4G3 (IgG2b), mAb-5G2 (IgG1), and mAb-9H2 (IgG1), all inhibit SEK-induced proliferation and cytokine production of human immune cells. We then demonstrate that passive immunization with a combination of mAb-4G3 and mAb-5G4, 2 mAbs that do not compete for epitope(s) on SEK, significantly enhance survival in a murine model of SEK-induced toxic shock (p = 0.006). In the setting of sepsis, passive immunization with this combination of mAbs also significantly enhances survival in mice after challenge with CA-MRSA strain USA300 (p = 0.03). Furthermore, septic mice that received mAb treatment in conjunction with vancomycin exhibit less morbidity than mice treated with vancomycin alone. Taken together, these findings suggest that the contribution of SEK to S. aureus pathogenesis may be greater than previously appreciated, and that adjunctive therapy with passive immunotherapy against SEs may be beneficial.

One hundred hospital environment samples were obtained in 2012 in a Tunisian hospital and tested for Staphylococcus aureus recovery. Antimicrobial resistance profile and virulence gene content were determined. Multilocus-sequence-typing (MLST), spa-typing, agr-typing and SmaI-pulsed-field gel electrophoresis (PFGE) were performed. Two methicillin-resistant S. aureus (MRSA) isolates typed as: ST247-t052-SCCmecI-agrI were recovered from the intensive care unit (ICU). Ten samples contained methicillin-susceptible S. aureus (MSSA) and these samples were collected in different services, highlighting the presence of the tst gene encoding the toxic shock syndrome toxin as well as the lukED, hla, hlb, hld and hlgv virulence genes in some of the isolates. In conclusion, we have shown that the hospital environment could be a reservoir contributing to dissemination of virulent S. aureus and MRSA.

Staphylococcal food poisoning represents one of the most frequently occurring intoxications, caused by staphylococcal enterotoxins (SE-s) and staphylococcal enterotoxin-like proteins (SEl-s). Therefore, there is a need for rapid, sensitive and specific detection method for this human pathogen and its toxin genes in food matrices. The present work is focused on Staphylococcus aureus detection by a nonaplex polymerase chain reaction, which targets the 23S rRNA gene for identification of S. aureus at the species level, genes for classical SE-s (SEA, SEC, SED), new SE-s (SEH, SEI), SEl-s (SEK, SEL) and tsst-1 gene (toxic shock syndrome toxin). Primers were properly designed to avoid undesirable interactions and to create a reliably identifiable profile of amplicons when visualized in agarose gel. According to obtained results, this approach is able to reach the detection sensitivity of 12 colony forming units from milk and meat matrices without prior culturing and DNA extraction.

Introduction: Staphylococcal food intoxication is dependent on the production of enterotoxins, the single most important virulence factors. Various studies conducted in Ethiopia have depicted the prevalence of S. aureus in bovine milk. However, there is no published data regarding the enterotoxin gene profile of S. aureus isolates in Ethiopia. The aim of this study was, therefore, to evaluate enterotoxin gene carriage profile of S. aureus isolates recovered from bovine milk samples from central Ethiopia. Methodology: In this study, 109 S. aureus isolates recovered from bovine milk were analyzed for carriage of the classical enterotoxin genes. Genomic DNA extraction was performed using a commercially available kit. Two sets of multiplex polymerase chain reaction (PCR) assays were used to detect the five classical enterotoxin-coding genes and the toxic shock syndrome toxin gene. Results: At least one type of S. aureus enterotoxin gene (SE) was carried in 73 (66.9%) of the isolates. The most frequently encountered gene was sea (40; 36.7%) followed by seb (19; 17.4%), see (18; 16.5%), tst (16; 14.7%), sec-1 (12; 11.01%), and sed (7; 6.4%). Of the 73 S. aureus isolates harboring at least one of the enterotoxin genes, 26 (35.6%) strains harbored more than one enterotoxin gene. Conclusions: More than half of the S. aureus isolates harbored at least one of the enterotoxin coding genes, indicating milk specimens contaminated by S. aureus could have a high chance of causing food intoxication.

Today Staphylococcus aureus strains harboring tst gene are considered to be one of the major public health challenges around the world. Regarding to lack of data on molecular characteristics of these strains, the present study was performed to investigate characteristics and prevalence of antibiotic resistance genes of different agr types of Staphylococcus aureus strains carrying tst gene. In this cross-sectional study, 58 Staphylococcus aureus isolates carrying tst gene related to wound infectiofns were investigated. Isolates were characterized for in vitro antimicrobial susceptibility, mecA gene presence, resistance gene detection, and agr typing. Prevalence of S. aureus harboring tst gene was 29.7%. Methicillin-resistant S. aureus were mainly present in S. aureus harboring tst gene (56.9%). Twenty-seven (46.2%) isolates were confirmed as multidrug resistance (MDR). Out of 12 mupirocin resistant isolates (20.7%), 4 (6.9%) and 8 (13.8%) were high and low-level mupirocin resistance respectively. The frequencies of cMLSB, iMLSB, and MS phenotypes were detected 25.9%, 17.2% and 6.9%, respectively. Among tested isolates, the predominant genes were mecA in 56.9% isolates, followed by tet(M) in 48.3%, aac (6′)-Ie/aph (2″) in 27.6%, ant (4′)-Ia and erm(C) each in 20.7%, aph (3′)-IIIa in 17.2%, msr(B) in 10.3%, erm(A) and mupA each in 6.9% and msr(A) in 1.7% of isolates. agr types detected in tested strains were mainly type I (36.2%), III (25.9%), II (20.7%), and IV (17.2%). These findings indicated relatively high resistance among methicillin-resistant S. aureus harboring tst gene which was distributed in agr type I highlighting particular importance of diagnosis of tst-positive S. aureus strains to choose appropriate antibiotics for the effective treatment of infections due to these bacteria.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of human infections worldwide, with major dominant lineage circulating in particular geographical regions. The Brazilian Epidemic Clone (BEC, SCCmec III, ST 239) has been predominant in most Brazilian hospitals. Here, we report the prevalence of MRSA SCCmec type II exhibiting different STs, most of them belonging to CC5 in a tertiary hospital in Southern Brazil.

Staphylococcus aureus (S. aureus) is an important causative agent of contagious intermammary infections in dairy cattle. S. aureus is also considered as an important foodborne pathogen and cause of food poisoning cases and outbreaks worldwide. In order to understand the molecular ecology of S. aureus, the present study compared phenotypic and genotypic characteristics of 70 S. aureus isolates from bovine mastitis milk samples collected during the period from August 2001 to March 2014 in different regions of Northern Germany. The S. aureus isolates were characterised phenotypically, as well as genotypically for their genetic diversity using multi-locus sequence typing (MLST), spa typing and the presence of virulence genes encoding 16 staphylococcal enterotoxins (sea-selu), toxic shock syndrome toxin (tst), thermonuclease (nuc), clumping factor (clfA and clfB), coagulase (coa) and the methicillin resistance gene mecA. A total of 16 sequence types were grouped into eight clonal complexes (CCs), and 17 spa types were identified. These included six novel sequence types and one novel spa type. The majority of bovine mastitis milk-associated sequence types belonged to the clonal complex CC5, CC97, CC133, and CC151 and showed closely related genotypes or lineages with sequence types of human origin. The genotype CC133 (ST133-t1403) was predominant, constituting 27.1% of the isolates. In addition, the S. aureus isolates displayed nine different enterotoxigenic profiles. All S. aureus were methicillin-susceptible (MSSA). The current study provides new information on phenotypic and genotypic traits of S. aureus isolates from bovine mastitis. The comparison of characteristics of isolates from the present study originating from mastitis milk showed similarities with human isolates. This might help to better understand the distribution of S. aureus in the one health context.

Atopic dermatitis (AD) is a chronic relapsing. itchy inflammatory condition of the skin usually associated with other allergic diseases such as asthma and hay fever. Following the initial occurrence of AD several factors such as environmental allergens, colonization with Staphylococcus aureus and allergen specific T cell responses are though, to aggravate the disease. The bacteria skin flora of patients wit h atopic dermatitis is strikingly different from that in healthy people in terms of the presence of Staphylococcus aureus. An altered epidermal barrier; increased bacterial adhesion, defective bacterial clearance and defective cutaneous innate immune response are among various factors contributing to this high bacterial colonization inAD Staphylococcus aureus strains with ability to secrete Staphylococcal enterotoxins A - D and the toxic shock syndrome toxin - 1 have been isolated from the skin of up to 65% of AD patients who are colonized with this microorganism. These toxins aggravate the disease by cellular activation to produce cytokines.

We report here the prevalence of the tst-1 gene among 252 methicillin-susceptible Staphylococcus aureus (MSSA) isolates and 458 methicillin-resistant S aureus (MRSA) isolates collected from 531 subjects between 2008 and 2017, one of which was recovered from a child with MRSA toxic shock syndrome. tst-1 was encoded by 43 (6%) S aureus isolates overall: 42 (16.7%) MSSA isolates and 1 (0.2%) MRSA isolate (P < .001).

A 32 year old female, an active intravenous drug user, was admitted for fever, myalgias and an erythematous macular rash on her distal extremities. She quickly decompensated and developed septic shock. Her examination was significant for a progressive rash which within two days developed bullae and necrosis with progression to a confluent rash involving her palms and soles (Figs. 1 and 2). Her rash involved nearly one third of her body with what was equivalent to a third degree burn. Her labs were significant for leukocytosis with bandemia, elevated liver function tests with worsening thrombocytopenia and fibrinogen levels consistent with disseminated intravascular coagulation (DIC) Her transthoracic echocardiogram (Fig. 3) showed a 5 cm vegetation on the tricuspid valve. Her blood cultures were positive for methicillin-sensitive Staphylococcus aureus. She was meeting the clinical criteria for toxic shock syndrome (TSS) and subsequent testing for toxic shock syndrome toxin antibody was positive. She was treated with antibiotics and intravenous gamma globulin (IVIG). Due to her worsening rash she was transferred to a burns unit. She was diagnosed with Purpura fulminans (PF) which is a skin manifestation of DIC and has a rare association with Staphylococcus aureus infection.The main focus of this case report is to emphasise this rare association, prompt an early diagnosis and referral to prevent life threatening complications. Keywords: Staphylococcal aureus, Toxic shock syndrome, Purpura fulminans, Disseminated intravascular coagulation

Made available in DSpace on 2018-12-11T17:22:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Bovine mastitis has been a concern for dairy herd for decades. The adaptation capacity of one of the main species responsible for this disease, Staphylococcus aureus (S. aureus), plays a pivotal role in this issue. The aim of this study was to establish a molecular and phenotypic profile of 285 S. aureus strains isolated from milk of subclinical mastitis cows from 18 different farms in São Paulo State using spa typing, multilocus sequence typing (MLST), pulsed field gel electrophoresis (PFGE), agr cluster (I, II, III and IV) typing, PCR for genes including enterotoxins (sea, seb, sec, sed, see, seg, seh, sei), toxic shock syndrome toxin (tsst-1), and Panton-Valentine leucocidin (pvl), as well as in vitro resistance assays for 12 antibiotics. The results showed a wide variety of strains with a high toxigenic potential; concomitantly, sec, seg and seh were prevalent. In addition, we observed a predominance of the spa types t605 (ST 126, CC126) and t127 (ST1, CC1) and the unusual presence of t321 causing bovine mastitis, which has been previously reported only in swine. The most frequent ST were ST126 (70.5%) and ST1 (10.5%). Regarding PFGE, we observed four major groups and six profile patterns. The highest resistance was observed for streptomycin (9.5%), followed by tetracycline (3.5%), clindamycin (9.3%), and erythromycin (2.8%). The tsst-1 gene was detected in 36.8% of isolates and pvl was not observed. One hundred and thirty-six (47.7%) isolates possessed agr type II, followed by types III (20%) and I (8.1%), with type IV not being detected. We observed that the same spa type could result in different PFGE profiles, so the exclusive use of spa type sequences can lead to incorrect interpretations regarding the spread of clones in an epidemiological context. Department of Microbiology and Immunology Institute of Bioscience São Paulo State University (UNESP) Department of Food Science Faculty of Food Engineering (FEA) University of Campinas (UNICAMP) Adolfo Lutz Institute Department of Hygiene Veterinary and Public Health Sao Paulo State University Botucatu-SP Department of Veterinary Clinical Medicine University of Illinois The Roslin Institute and Edinburgh Infectious Diseases University of Edinburgh, Easter Bush Department of Microbiology and Immunology Institute of Biosciences Sao Paulo State University - UNESP, Post Office Box 510 Department of Microbiology and Immunology Institute of Bioscience São Paulo State University (UNESP) Department of Hygiene Veterinary and Public Health Sao Paulo State University Botucatu-SP Department of Microbiology and Immunology Institute of Biosciences Sao Paulo State University - UNESP, Post Office Box 510 FAPESP: 2013/12831-4 FAPESP: 2013/18338-8

Coagulase-negative Staphylococcus spp. (CNS) are the main microorganisms involved in ovine mastitis. Treatment at the end of lactation can contribute towards cure and prevention of subclinical cases during the subsequent lactation. However, virulence factors and resistance mechanisms presented by CNS can decrease cure rates. The aims of the study were to identify the species of CNS in milk of mastitic ewes with and without antimicrobial treatment, and to investigate the presence of genes relating to resistance of β-lactam antimicrobials, formation of biofilms, production of enterotoxins and production of the toxic shock syndrome toxin. Cases of failure in the treatment were related with the presence/absence of the respective genes. Sixty sheep were divided into three groups: G1, without treatment; G2, animals treated via the intramammary route with 100mg of cloxacillin during drying off; and G3, sheep treated via the intramammary route with 50 mg of nanoparticulate cloxacillin. Milk samples were gathered during drying off and 15 and 30 days after the parturition of the subsequent lactation. The analyses to identify the species of CNS were carried out by means of the internal transcribe spacer technique and the investigation of the genes responsible for the virulence factors and resistance to oxacillin was performed using the polymerase chain reaction (PCR) technique. No sample was positive for the mecA gene. The only gene relating to production of enterotoxins was sec. Among the genes relating to production of biofilm, icaD was the only one identified in the three experimental groups. Staphylococcus warneri was the main species of CNS isolated during the pre and post-partum periods of the sheep. The species carrying genes relating to production of enterotoxins and biofilms were present in uncured sheep. RESUMO: Staphylococus spp. coagulase-negativos (SCN) estão entre os principais micro-organismos envolvidos na mastite ovina. O tratamento ao final da lactação pode contribuir com a cura e a prevenção de casos subclínicos durante a lactação seguinte. Todavia, fatores de virulência e mecanismos de resistência apresentados por SCN podem reduzir as taxas de cura. Os objetivos desse estudo foram identificar as espécies de SCN no leite de ovelhas com mastite com e sem tratamento antimicrobiano e investigar a presença de genes relacionados com resistência a antibióticos beta lactâmicos, formação de biofilmes, produção de enterotoxinas e produção da toxina da síndrome do choque tóxico. Casos de falhas no tratamento foram relacionados com a presença/ausência dos respectivos genes. Sessenta ovelhas foram divididas em três grupos: G1, sem tratamento; G2, animais tratados via intramamária com 100mg de cloxacilina antes da secagem; e G3, ovelhas tratadas via intramamária com 50 mg de cloxacilina nanoparticulada. Amostras de leite foram obtidas durante a secagem e 15 e 30 dias depois do parto na lactação seguinte. As análises para identificar as espécies de SCN foram conduzidas por meio da técnica de Internal transcribe spacer e a investigação dos genes responsáveis pelos fatores de virulência e resistência à oxacilina foi realizada usando a técnica reação em cadeia da polimerase. Nenhuma amostra foi positiva para o gene mecA. O único gene relacionado com a produção de enterotoxinas foi o sec. Dentre os genes relacionados com a produção de biofilme, icaD foi o único identificado nos três grupos experimentais. Staphylococcus warneri foi a principal espécie de SCN isolada durante o pré e pós-parto. As espécies que apresentaram genes relacionados com a produção de enterotoxinas e biofilmes estavam presentes nas ovelhas não curadas.

International audience; The current study aimed to characterize Staphylococcus aureus isolates from foodstuffs collected from western Algeria. A total of 153 S. aureus isolates from various raw and processed foods were obtained and identified using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. Isolates were characterized by antimicrobial susceptibility testing and toxin gene detection. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were identified by detection of the mecA gene and characterized by staphylococcal cassette chromosome mec (SCCmec) typing. We found that 30.9% (153/495) of food samples were contaminated with S. aureus. Thirty-three (21.5%) S. aureus isolates were identified as MRSA, and 16.9% (26/153) carried the mecA gene. Three SCCmec types were identified of which type IV was the most common (69.2%) followed by type V (15.3%) and type II (7.6%). Two MRSA isolates were not typable with SCCmec typing. None of the examined isolates harbored mecC. Furthermore, 14.3% (22/153) of the isolates were toxigenic S. aureus. The cytotoxin gene pvl was detected in 11.1% of the S. aureus isolates. This gene was more commonly detected (76.4%) in MRSA isolates than in methicillin-suceptible Staphylococcus aureus (MSSA) isolates. The tsst-1 gene coding for toxic shock syndrome toxin was isolated rarely (3.2%) and only in MSSA isolates. According to disk diffusion test results, 70 isolates were resistant to only one antimicrobial drug, and 51 (33.3%) isolates were multidrug resistant. Other 32 isolates were susceptible to all antibiotics. Our study highlights, for the first time, a high prevalence of multidrug-resistant S. aureus isolates carrying pvl or tsst-1 found in food products in Algeria. The risk of MRSA transmission through the food chain cannot be disregarded, particularly in uncooked foods.

Neonatal toxic shock syndrome (TSS)-like exanthematous disease (NTED) is a syndrome first reported in Japan. Neonates develop systemic exanthema, thrombocytopenia, and fever usually during the first week of life. The disease is distinguished from frank TSS because affected infants are not severely ill and do not meet TSS criteria. Most infants are confirmed to be colonized with TSST-1 producing strains of S. aureus. Suggested diagnostic criteria for NTED include a skin rash with generalized macular erythema and one of the following symptoms: fever >38.0°C, thrombocytopenia

Staphylococcus (S.) aureus plays a role in the pathogenesis of atopic dermatitis (AD), possibly via the expression of various virulence antigens. An altered antibody response towards these antigens might contribute to inflammation. We aimed to provide an overview of the varying prevalences and odds of antibody responses against S. aureus antigens in AD patients. Data were systematically obtained from Embase, Medline, Web of Science, Scopus, Cochrane, PubMed and Google Scholar (up to February 12th 2016). We selected all original observational and experimental studies assessing anti-staphylococcal antibodies in serum of AD patients. Prevalences and odds ratios (ORs) of immunoglobulin (Ig) E, IgG, IgM, IgA against S. aureus in AD patients versus healthy controls were pooled using the random-effects model. We calculated I2 statistics to assess heterogeneity and rated study quality using the Newcastle-Ottawa Scale. Twenty-six articles (2369 patients) were included of which 10 controlled studies. Study quality was fair to poor. AD patients had higher prevalences of IgE against staphylococcal enterotoxin (SE) A (OR 8.37, 95% CI 2.93-23.92) and SEB (OR 9.34, 95% CI 3.54-24.93) compared to controls. Prevalences of anti-staphylococcal IgE were 33% for SEA, 35% for SEB and 16% for toxic shock syndrome toxin (TSST)-1. However, study heterogeneity and imprecision should be taken into consideration when interpreting the results. Data on IgG, IgM and IgA as well as other antigens are limited. In conclusion, AD patients more often show an IgE antibody response directed against S. aureus superantigens compared to healthy controls supporting a role for S. aureus in the AD pathogenesis. This article is protected by copyright. All rights reserved.

Stress leads to immune malfunction and increased susceptibility to infection resulting in impaired cognitive behavior and depression. Working with an animal model of Staphylococcus aureus infection and restraint stress we demonstrated impaired immune response and altered behavior against the S. aureus infection after exposure to acute or chronic restraint stress. This enhanced the resistance of mice to S. aureus infection via inhibiting the production of pro-inflammatory cytokines, free radicals, and upregulating corticosterone and anti-inflammatory cytokine production, resulting in altered exploratory behavior, compared to non-stressed infected group (P

Treatment of Staphylococcus aureus infections has become complicated owing to growing antibiotic resistance mechanisms and due to the multitude of virulence factors secreted by this organism. Failures with traditional monovalent vaccines or toxoids have brought a shift towards the use of multivalent formulas and neutralizing antibodies to combat and prevent range of staphylococcal infections. In this study, we evaluated the efficacy of a fusion protein (r-ET) comprising truncated regions of staphylococcal enterotoxin A (SEA) and toxic shock syndrome toxin (TSST-1) in generating neutralizing antibodies against superantigen induced toxicity in murine model. Serum antibodies showed specific reactivity to both SEA and TSST-1 native toxins. Hyperimmune serum from immunized animals protected cultured splenocytes from non-specific superantigen induced proliferation completely. Passive antibody administration prevented tissue damage from acute inflammation associated with superantigen challenge from S. aureus cell free culture supernatants. Approximately 80% and 50% of actively and passively immunized mice respectively were protected from lethal dose against S. aureus toxin challenge. This study revealed that r-ET protein is non-toxic and a strong immunogen which generated neutralizing antibodies and memory immune response against superantigen induced toxic effects in mice model.

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent source of infection in the neonatal intensive care unit (NICU), often associated with significant morbidity. Active detection and isolation (ADI) programs aim to reduce transmission. We describe a comprehensive analysis of the clinical and molecular epidemiology of MRSA in an NICU between 2003 and 2013, in the decade following the implementation of an MRSA ADI program. Molecular analyses included strain typing by pulsed-field gel electrophoresis, mec and accessory gene regulator group genotyping by multiplex PCR, and identification of toxin and potential virulence factor genes via PCR-based assays. Of 8,387 neonates, 115 (1.4%) had MRSA colonization and/or infection. The MRSA colonization rate declined significantly during the study period from 2.2 to 0.5/1,000 patient days (linear time, P = 0.0003; quadratic time, P = 0.006). There were 19 cases of MRSA infection (16.5%). Few epidemiologic or clinical differences were identified between MRSA-colonized and MRSA-infected infants. Thirty-one different strains of MRSA were identified with a shift from hospital-associated to combined hospital- and community-associated strains over time. Panton-Valentine leukocidin-positive USA300 strains caused 5 of the last 11 infections. Staphylococcal cassette chromosome mec (SCC mec ) types II and IVa and agr groups 1 and 2 were most predominant. One isolate possessed the gene for toxic shock syndrome toxin; none had genes for exfoliative toxin A or B. These results highlight recent trends in MRSA colonization and infection and the corresponding changes in molecular epidemiology. Continued vigilance for this invasive pathogen remains critical, and specific attention to the unique host, the neonate, and the distinct environment, the NICU, is imperative.

Staphylococcus aureus is one of the major contagious pathogens causing bovine mastitis worldwide.1 It causes contagious mastitis resulting either clinical or subclinical mastitis with increase in the number of somatic cell count (SCC) in milk. More than $130 million is lost by the Australian dairy farmers ($A200/cow/year) every year due to poor udder health caused by mastitis resulting in reduction of milk production, increase in treatment costs, veterinary consultation fees, and number of cow culls. There are multiple pathogens that have been found to be associated with bovine mastitis in Australia.2 While the relative distribution of the different pathogens causing mastitis may differ in different regions and countries, S. aureus is one of the most significant contagious bacterial pathogens causing bovine mastitis and is of concern to public health because of its potential for transmission to humans. Once the organism enters into the mammary gland, it adheres to epithelial lining and defies the host innate immune defenses by variety of virulence factors such as capsule and protein A which interfere with the process of phagocytosis.3 Once intra-mammary infection is established, damage to the mammary gland epithelial lining is initiated by ulceration and occlusion of lactiferous ducts and alveoli, infiltration of inflammatory cells in the parenchyma.4 S. aureus produces a variety of virulence factors which evade the tissue and host immune system and thereby maintain infection. These virulence factors are capsular polysaccharides, cytotoxins, superantigenic enterotoxins and MSCRAMM (microbial surface components recognizing adhesive matrix molecules). A large number of cytotoxins are produced by S. aureus which form pores in the cell membrane causing osmotic swelling leading to cell death. These cytotoxins include leukocidins, phenol soluble modulins (PSMs) and cytolysins. The cytolysins of S. aureus are α-, β-, γ-, and δ-toxins, of which α-toxin is well characterized for its contribution to biofilm formation and protective potential.5,6 β-toxin is a sphingomyelinaseC and 95% of S. aureus isolates from bovine mastitis cases produce β-toxin7 which causes damage to epithelial lining of mammary gland. Gamma (γ) and delta (δ) toxins, bicomponent toxins are synergohymenotropic toxins that act through the synergistic activity of 2 non-associated secretory proteins creating lytic pores in host cells including neutrophils and are assembled from the 2 components secreted separately by the organism as water-soluble molecules.8 Panton-Valentine Leukocidin (PVL) is encoded by 2 contiguous and cotranscribed genes, LukS-PV and LukF-PV9 and creates lytic pores in neutrophils, monocytes and macrophages adversely affecting their function. Phenol soluble modulins (PSMs) are the peptides produced by S. aureus, which are cytotoxic and proinflammatory agent. Recent finding has demonstrated that it plays a part in the formation of S. aureus biofilm.10 S. aureus produces a number of superantigens including enterotoxins (SEs), Toxic Shock Syndrome toxin and exfoliative toxins. Enterotoxins of S. aureus include the classical enterotoxins A to E and the recently identified and characterized SEG-SEU toxins.11,12 These antigens are considered as superantigens due to their ability to release inflammatory cytokines from both T cells and macrophages by binding to the surface of MHC class II proteins and T cell receptors. 13-16 The first step in establishing infection is the initial attachment of S. aureus to eukaryotic membrane and extracellular matrix proteins which is followed by colonization and subsequent infection.17 Colonization is commonly associated with a variety of adherence factors or adhesins which are known as microbial surface component recognizing adhesive matrix molecules (MSCRAMM). There are over 20 different MSCRAMMs identified, which can be expressed in S. aureus18 that mediate attachment to surface proteins of host cells including collagen, elastin, fibrinogen, thrombospondin, fibronectin, bone sialoprotein and laminin.19 Major adhesins in this group that mediate the initial attachment of S. aureus to the bovine mammary gland, providing the first critical step for establishing infection19 are clumping factors A and B (ClfA and ClfB),20 collagen adhesion (CNA),21 bone sialo binding protein (BBP)22 and the fibronectin binding proteins A and B (FnBPA and FnBPB).23 Besides these major adhesins, biofilm-associated protein (bap) has also been reported to be associated with primary attachment of S. aureus to mammary tissue.24,25 An accessory gene, agr, regulates the production of biofilms including detachment of biofilm that helps in virulence and dissemination of S. aureus in the mammary gland resulting in persistent bovine mastitis,26 whereas penicillin resistance of S. aureus is mediated by blaZ gene.27 Variability in the prevalence of virulence factors in S. aureus may result in various levels of severity and forms of mastitis in cows.28 No studies have been carried out in Australia on the virulence factors of S. aureus isolated from clinical cases of bovine mastitis. Aim of this study was to determine the relative distribution of different virulent factors of bovine S. aureus isolates in Australia including MSCRAMMS and exotoxins using conventional polymerase chain reaction (PCR) and the available serological methods.

Antibiotic resistant bacteria are a worldwide health concern and it is essential to develop new antimicrobial agents to kill these bacteria and to reduce the use of antibiotics. Staphyloccus aureus (S.aureus) an important medical pathogen is responsible for many wound infections and up to 25% of all strains produce the toxic shock syndrome toxin (TSST-1) which stimulates the release of inflammatory cytokines which cause fever and shock. Here we report on the inhibition of two penicillin resistant TSST-1 producing strains of S.aureus by seven different honeys. Bacterial growth was reduced after 24 hours at 37oC, from 10.0 log 10 in the TSB growth control to less than 1.0 log 10 in Highland, Chilean and Manuka honey. TSST-1 production was reduced from 256ng/ml in the TSB growth control to less than 30 ng/ml in sub inhibitory concentrations of all honeys.

Staphylococcus aureus (S. aureus) is considered as a notorious nosocomial pathogen among hospitalized patients and community-dwelling subjects. Its increasing morbidity and mortality is believed to be due to antibiotic resistance. However, the data concerning molecular properties of infecting strains are few. In this study, a total of 192 S. aureus strains, including 88 (45.8%) meticillin-sensitive S. aureus (MSSA) and 104 (54.2%) meticillin-resistant S. aureus (MRSA) were recovered from clinical samples. The prevalence of subtypes containing staphylococcal cassette chromosome mec (SSCmec), staphylococcal enterotoxins (SEs), toxic shock syndrome toxin (TSST) and exfoliative toxin was assessed by PCR. Antibiotic susceptibility pattern and vancomycin resistance of each isolate were evaluated by disk diffusion method and micro-dilution method, respectively. 9 (2.3%) strains required MIC 2 mg/l of vancomycin, which significantly increased among multi drug resistant (MDR), MRSA and SCCmec type III strains (p 0.05). 171 (89%), 140 (72.91%), 7 (3.6), 78 (48.6%), 5 (2.6%), 151 (78.64%), 129 (67.18%), 178 (92.7%) and 15 (7.8%) of 192 isolates harbored mecA, entA, entB, entC, entD, entE, eta, etb and tsst-1 genes, respectively. 31 (16.14%), 5 (2.6%), 95 (49.48%) and 7 (3.64%) of 192 isolates carried SCCmec type I, II, III and IV, respectively. We found a significantly higher rate of MRSA and resistance to all tested antibiotics, except to penicillin G, kanamycin and linezolide among the SCCmec type III class (p 0.05). According to our findings, MSSA isolates should be taken as seriously as MRSA strains due to the potential presence of broad spectrum virulence factor genes.

Toxic shock syndrome (TSS) caused by methicillin-resistant Staphylococcus aureus (MRSA) nosocomial infection is a growing concern in both adult and pediatric patients. The reason why TSS appears in only some patients with MRSA infection remains unclear. In this study, we analyzed serial TSS toxin-1 (TSST-1) antibody in patients with burn injury to investigate the mechanisms of TSS caused by MRSA nosocomial infection. This study comprised of patients with burn injury in our burn care unit from September, 2010 to August, 2011. Serum samples were collected serially on admission, at 48 to 72 hours after injury, on the day MRSA infection appeared, and on the day MRSA infection resolved. TSST-1 antibody was measured by enzyme-linked immunosorbent assay (ELISA). TSS was diagnosed according to the criteria of the Centers for Disease Control. Serial serum samples were collected from 24 patients and nosocomial MRSA infection was detected in 12 patients. In these 12 patients, TSS occurred in five patients (TSS+ group) but did not occur in the other seven patients (TSS- group). TSST-1 antibody level was significantly lower in the TSS+ group than TSS- group on admission and on the day MRSA infection appeared. All patients in the TSS+ group received intravenous immune globulin when TSS was diagnosed, and no patients died of TSS. Patients suffering from TSS had a lower level of TSST-1 antibody than patients not suffering from TSS. Testing for TSST-1 antibody in the clinical setting might help to predict and prevent the appearance of TSS caused by nosocomial MRSA infection.

Background: Cystic fibrosis (CF) is the most common life-limiting inherited disease in Caucasian populations. While pathological changes can be seen in various organs, morbidity and mortality are mainly related to the respiratory tract, with patients suffering from chronic bronchopulmonary infections with characteristic pathogens including Staphylococcus aureus.Objectives: To date, there is only very limited data on the genetic and phenotypic characteristics of S. aureus in CF patients. Therefore, in our study, we characterized 58 S. aureus isolates collected from CF patients in Austria by spa typing, DNA microarray profiling, as well as antimicrobial susceptibility testing in order to determine common genomic and antimicrobial resistance features. The tested strain collection exhibited high genomic diversity. Results: The 58 isolates were assigned to 16 clonal complexes and 48 spa types and differed greatly regarding their virulence and resistance gene profiles. The predominant clonal complexes were MLST CC30 (22%), CC15 (16%), CC45 (14%), and CC5 (12%), complexes that are highly prevalent worldwide among S. aureus strains isolated from humans colonized or infected with S. aureus. DNA microarray profiles showed a wide variety of genes encoding antimicrobial resistance and virulence factors such as various leukocidins, haemolysins, enterotoxins, exfoliative toxins, toxic shock syndrome toxin, as well as genes involved in adhesion and immune evasion. Conclusions: While a large number of strains exhibited resistance to one or several antimicrobial agents, methicillin-resistant S. aureus was found at a low prevalence of 3% (n = 2) only. The two methicillin-resistant S. aureus isolates were assigned to CC152/t355 (SCCmecV) and CC5/t001 (SCCmecI). This is the first study to genetically characterize S. aureus isolates in CF patients in Austria.

Objectives: Emergence of methicillin resistant Staphylococcus aureus (MRSA) is a major medical problem of current era. These bacteria are resistant to most drugs and rapid diagnosis can provide a clear guideline to clinicians. They possess specific virulence factors and relevant information can be very useful. We designed this study to develop multiplex PCRs to provide rapid information. Methods: We studied 60 Staphylococcus aureus isolates and detected methicillin resistance by cefoxitin sensitivity and targeting of mecA gene. After initial studies with uniplex PCRs we optimized two multiplex PCRs with highly reproducible results. The first multiplex PCR was developed to confirm genus, species and methicillin resistance simultaneously, and the second multiplex PCR was for screening of virulence factors. Results: We found 38.33% isolates as methicillin resistant. α -toxin, the major cytotoxic factor, was detected in 40% whereas β-hemolysin was found in 25% cases. Panton Valentine leucocidin was detected in 8.33% and toxic shock syndrome toxin in5% cases. The results of uniplex and multiplex PCRs were highly compatible. Conclusions: These two multiplex PCRs when run simultaneously can provide vital information about methicillin resistance and virulence status of the isolate within a few hours as compared to several days needed by routine procedures.