BACKGROUND: Evidence supporting beta-lactam plus vancomycin synergy for methicillin-resistant (MRSA) continues to grow. Current evidence demonstrates that combination therapy is associated with shorter time to blood sterilization than vancomycin monotherapy. However, this combination has not been reported as salvage therapy for persistent MRSA bacteremia. CASE REPORT: We report a case of an 81-year-old male who was successfully treated with vancomycin plus nafcillin after failing vancomycin monotherapy, daptomycin monotherapy, and daptomycin plus gentamicin combination therapy. The patient originally presented with sepsis from a suspected urinary tract infection. Blood cultures drawn on days 1, 3, 5, 15, 19, 23, and 28 remained positive for MRSA despite multiple antimicrobial therapy changes. On day 29, therapy was changed to vancomycin plus nafcillin. Blood cultures drawn on day 32 remained negative. After 11 days, nafcillin was changed to piperacillin-tazobactam due to an infected decubitus ulcer. The combination was continued for 42 days after achieving blood sterility, 71 days after the patient originally presented. Evidence regarding salvage therapy for persistent bacteremia is sparse and is limited to case reports and case series. CONCLUSION: This case report supports that vancomycin plus an anti-staphylococcal beta-lactam combination should be further studied as salvage therapy for persistent MRSA bacteremia.

Methicillin Resistant Staphylococcus Aureus (MRSA) has been receiving significant attention, highlighting an increased risk of infectious transmission associated with athletic participation. As MRSA infections are becoming increasing virulent, athletic trainers are presented with immediate prevention challenges. While recommendations have been offered by the Centers for Disease Control and Prevention outlining basic prevention procedures, adherence to proposed guidelines and actual perception of the threat still pose the greatest hurdles to eradication of MRSA. Success in control and prevention of transmission of MRSA in athletic environments can be furthered by first investigating the perceptions of the problem in one of the first line of defense for athletes—their athletic trainers. Of particular importance are the perceptions of trainers' adherence to guidelines, perceptions of protocol standards, and relative threat of MRSA in the athletic environment. This study attempts to determine these perceptions and predict how athletic trainers will receive and adhere to standardized guidelines through written policy for MRSA prevention. Results reflect an increase in the awareness of MRSA as a threat to athletics since 2004. Overall positive perception of the development of guidelines and protocols specifically targeted to prevention of MRSA transmission in the athletic environment were also defined through this study. Athletic trainers surveyed expressed strong desire for additional training in procedures specific to reducing transmission of MRSA to prevent outbreaks. / Ph. D.

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious public health problem nationwide, threatening to develop into an epidemic. Many of these patients are presenting to their primary care clinics with skin and soft tissue infections (SSTIs). The CDC has reported that in 2005, MRSA was responsible for an estimated 94,000 life-threatening infections and 16,650 deaths. The purpose of this study is to estimate the incidence of CA-MRSA within a specific family practice in Florida and to identify epidemiologic factors, classify antibiotic susceptibility patterns, and evaluate patient education in regard to disease management and prevention. This study was a descriptive, epidemiologic, three-year retrospective medical record review of all wound cultured skin and soft tissue infections that presented to a family practice between January 2007 and December 2009. Sixty-two medical records met the inclusion and exclusion criteria for the study. Of these 62 SSTIs, 44 cultures grew one or more bacterial organisms. The incidence of CA-MRSA was 66% (n=29). The mean age of those with CA-MRSA was 40 years old, with a range from 7 to 90 years old. Sixty-two percent (n=18) were male and 38% (n=11) were female; additionally 69% (n=20) lived within a 10 mile radius from the family practice, while 31% (n=9) lived in a surrounding suburb. The most frequent race was Caucasian 83% (n=24), with African American at 10% (n=3) and Hispanics 7% (n=2). Risk factors associated with CA-MRSA was obesity 41% (n=10), diabetes mellitus 24% (n=7), and a previous history of MRSA infection 24% (n=7). Skin and soft tissue infections were diagnosed as either an abscess 62% (n=18), boil 24% (n=7), pustule 10% (n=3), or cellulitis 4% (n=1). CA-MRSA isolates were susceptible to trimethoprim-sulfamethoxazole 100% (n=29), doxycycline 93% (n=27), and rifampin 100% (n=14). Clindamycin susceptibility was 65% (n=15) with resistance at 30% (n=7) and 5% (n=1) intermediate. Both cephalexin and erythromycin were 100% resistant. Documentation in the medical record on wound care was found in 45% (n=13) of the records. The incidence of CA-MRSA SSTI was 66%, which identifies this suburban community at high risk for this bacterial infection. Risk factors associated with CA-MRSA included obesity (BMI > 30), history of previous MRSA infection, and diabetes mellitus. There were no clinical characteristics that helped distinguish MRSA infection from other bacterial SSTIs. Most SSTI were treated with incision and drainage and a susceptible antibiotic. Judicious use of antibiotics not only provides appropriate treatment, but is also critical in prevention of antibiotic resistance. Lastly, patient education in adequate hygiene is essential in preventing the spread of CA-MRSA

No description available.

No description available.

Quaternary ammonium compounds (QACs) have long served as lead disinfectants in residential, industrial, and hospital settings. Their simple yet effective amphiphilic nature makes them an ideal class of compounds through which to explore antibacterial activity. We have developed novel multiQAC scaffolds through simple and cost-efficient syntheses, yielding hundreds of diverse compounds strategically designed to examine various aspects of antibacterial and anti-biofilm activity, as well as toxicity. Many of these bis-, tris-, and tetraQACs display antibacterial activity 10 to 100 times greater than conventional monoQACs, and are among the most potent biofilm eradicators to date. Through analyzing their activity against several strains, we have uncovered and provided further evidence for key tenets of amphiphilic QAC bioactivity: a balance of hydrophobic side chains with cationic head groups generates optimal antibacterial activity, though toxicity to eukaryotic cells needs to be mitigated. Given their ubiquitous nature and chemical robustness, the overuse of QACs has led to the development of QAC resistance genes that are spreading throughout the microbial world at an alarming rate. These resistant strains, when found in bacterial biofilms, are able to persist in the presence of lead commercial QAC disinfectants, warranting the development of next-generation biocides. Several of our scaffolds were designed with QAC resistance machinery in mind; thus, we utilized these compounds not only as antibacterial agents but also as chemical probes to better understand and characterize QAC-resistance in methicillin-resistant Staphylococcus aureus (MRSA). Our findings support previous postulations that triscationic QACs would retain potency against QAC-resistant strains. Furthermore, we have identified monocationic and aromatic moieties, as well as conformational rigidity, as being more prone to recognition by the resistance machinery. Using our chemical toolbox comprised of QACs of various charge state and scaffold, we explored both the mechanism and scope of QAC-resistance by examining their structure-resistance relationship. Our holistic findings have allowed us to better understand the dynamics of this system towards the design and development of next-generation QACs that will: (1) allow us to better probe the resistance machinery, and (2) remain efficacious against a variety of microbial pathogens. / Chemistry

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-28T19:21:24Z No. of bitstreams: 1 rodrigo-muller.pdf: 1238864 bytes, checksum: 6c267fda3ccb992508b5424e77147783 (MD5) / Made available in DSpace on 2012-11-28T19:21:24Z (GMT). No. of bitstreams: 1 rodrigo-muller.pdf: 1238864 bytes, checksum: 6c267fda3ccb992508b5424e77147783 (MD5) Previous issue date: 2009 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / As infecções causadas por Staphylococcus aureusresistentes à meticilina (MRSA) são temidas em virtude da dificuldade de seu tratamentoe da elevada morbidade associada. A PBP2a (penicillin binding protein 2a), enzima responsável pela síntese da parede celular em MRSA, apresenta baixíssima afinidade porbeta-lactâmicos. Pelo fato de a PBP2a estar localizada na superfície externa, a mesma seria acessível ao sistema imune. Durante as infecções causadas por MRSA, pouco se sabe se o hospedeiro infectado ou colonizado desenvolve anticorpos anti-PBP2a e se osmesmos seriam protetores ou não. O presente projeto tem por finalidade avaliar a presença e níveis de anticorpos anti-PBP2a em um grupo de 56 pacientes colonizados por MRSA e investigar se estes anticorpos seriam protetores ou não. Os resultados gerados permitiram observar que 71% das amostras analisadas apresentaram anticorposanti-PBP2a pelo teste ELISA. Estas amostras foram submetidas à Western blot paraconfirmação, demonstrando que 46% das amostras possuíram anticorpos anti-PBP2a. Após estes resultados, as amostras positivas foram submetidas à purificação para avaliar a cinética de crescimento de MRSA. Foi observado que houve ligeira redução do crescimento bacteriano entre amostras de soro com anticorpos MRSA comparadas comas de soro com anticorpos anti-MSSA (PBP2a negativos). Por conseguinte avaliamos a curva de crescimento de MRSA em presença de imunoglobulinas purificadas de soro de pacientes colonizados por MRSA, (quantificação bacteriana). Observamos que houve uma redução drástica do crescimento bacteriano em presença destas imunoglobulinas. Os resultados obtidos indicaram que: (i) pacientes colonizados por MRSA podem produzir anticorpos anti-PBP2a e (ii) estes anticorpos podem conferir proteção contra MRSA. Estes dados parecem indicar que uma potencial vacina anti-PBP2apoderia ser efetiva para prevenção de infecções causadas por MRSA, como também para o emprego de imunoterapia passiva para o tratamento de pacientesinfectados por este patógeno. / Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are feared because of the difficulty of their treatment and the high associated morbidity. The PBP2a (penicillin binding protein 2a), the enzyme responsible for cell wall synthesis in MRSA, presents low affinity for beta-lactams. Because of the PBP2a is located on the external surface, it would be accessible to the immune system. During the MRSA infections, little is known whether the infected orcolonized host can produce antibodies anti-PBP2a and whether these antibodies would be protective or not. This project aims to assess the presence and levels of anti-PBP2a in a group of 56 patients colonized by MRSA and investigate whether these antibodies wouldbe protective or not. The results showed that 71% of the samples presented anti-PBP2aantibodies in ELISA. These samples which were subjected to Western blot for confirmation, it was demonstrated that 46% of the samples presented antibodies anti-PBP2a. After these results, the positive samples were subjected to purification to assess the MRSA growth kinetics. It was observed that there was a slight reduction in bacterial growth between serum samples with antibodies and MRSA compared to those of the serum with anti-MSSA (PBP2a negative). Therefore, the curve of growth ofMRSA was evaluated in the presence of purified immunoglobulins from the serumof patients colonized by MRSA (bacterial quantification). We observed that there was a drastic reduction in bacterial growth in the presence of immunoglobulins, thus demonstrating that these antibodies could have a protective action. These results indicated that: (i) MRSA colonized patients can produce antibodies against PBP2a and (ii) these antibodies can be protective against MRSA. These data suggest that a potential vaccine anti-PBP2a could be effective for prevention of infections caused byMRSA and for the use of passive immunotherapy in the treatment of patients infectedby this pathogen.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Numerous studies conducted internationally have identified and described several endemic methicillin-susceptible Staphylococcus aureus (MSSA) clones. However, only some of these clones are associated with methicillin resistance (CC5, CC8, CC22, CC30 and CC45). To date, studies reporting on the population structure of S. aureus isolated in South Africa represent limited demographic areas, focus on methicillin-resistant S. aureus (MRSA) only and have displayed little emphasis on virulence. This study was undertaken to elucidate the population structure of S. aureus isolated from specific clinical sources at Tygerberg hospital, and to investigate specific host-pathogen interactions of representative isolates. Consecutive non-repetitive clinical S. aureus isolates were collected over one year (September 2009/2010) with patient demographics and limited clinical information. Strains were typed by PFGE and molecular markers (spa, multi-locus sequence typing (MLST), agr, Staphylococcal Chromosome Cassette mec and Panton-Valentine leukocidin (PVL)). Representative isolates were selected and investigated for the presence of virulence genes, adherence (to immobilised fibronectin [Fn], fibrinogen [Fg], collagens IV [CnIV] and VI [CnVI]), cellular invasion and cell death induction. Statistical association were determined between all in vitro results and methicillin-resistance, clonality, patient HIV status and bacterial PVL status. Fifteen percent of the isolates (n = 367) were MRSA. Forty four present of isolates were PVL+. agr I-IV and SCCmec I-V were identified. The MSSA population was diverse: ST22 (dominant), ST1865 and ST121 were PVL+. ST45, ST1863 and ST15 were PVL-. PVL- MRSA were diverse: ST612-MRSA-IV (dominant), ST5-MRSA-I, ST239-MRSA-III, ST36-MRSA-II and ST22-MRSA-IV. The genes fnbA/B (fibronectin-binding protein A/B), clfA/B (clumping factor A/B), eap (extracellular adherence protein), nuc (nuclease), coa (coagulase) and hld (delta toxin) were detected in all representative isolates. The CC8 and CC6 isolates adhered strongly to all ligands (100-700% of control, ligand dependent), while isolates of CC45, CC22 and CC88 adhered strongly only to Fg and Fn. The CC30, CC15, and CC12 isolates adhered extremely strongly to CnIV (>300%) and CC8, CC15, and C6 to CnVI (>200%). Isolates from CC30, CC8, CC15, CC6, CC12, CC97, CC88 and CC45 were highly invasive (>100%). ST121 was non-invasive (>50%). Isolates of CC5, CC30 and CC121 were non-cytotoxic (<50%), while isolates of CC22, CC8, CC15, CC45 and CC88 were very cytotoxic (>70%). No significant difference was observed in adherence or cell death induction of MRSA vs. MSSA clones or between isolates from HIV+ vs. HIV- persons. PVL- isolates displayed higher cellular invasiveness than PVL+ isolates. The presence of ST612-MRSA-IV, ST22-MRSA-V and ST8-MRSA-V points to local SCCmec acquisition, as we found MSSA isolates with the same spa types. Numerous MSSA clones were prevalent, but do not appear to have a major common genetic background with MRSA. PVL was highly prevalent among MSSA, indicating acquisition of PVL genes independently of SCCmec. The abilities to adhere to specific immobilised ligands in vitro were diverse and grouped with the genetic background, while the vast majority of isolates were invasive and induced significant cell death. We can conclude that the population of S. aureus at Tygerberg hospital is composed of a vast number of MSSA and MRSA clones, which display varying patters of adherence to selected ligands and of which, the majority clones are invasive and cytotoxic. / AFRIKAANSE OPSOMMING: Talle internasionale studies het verskeie endemiese metisillien vatbare Staphylococcus aureus (MSSA) klone geïdentifiseer en beskryf. Slegs 'n paar van hierdie klone word geassosieer met metisillien weerstandigheid (Klonale kompleks (KK) 5, KK8, KK22, KK30 en KK45). Studies oor die bevolking struktuur van S. aureus geïsoleer in Suid-Afrika is tot dusver beperk tot demografiese gebiede, fokus slegs op metisillien-weerstande S. aureus (MRSA) en het min klem op virulensie geplaas. Hierdie studie is onderneem om die bevolking struktuur van S. aureus, geïsoleer vanaf spesifieke kliniese bronne, in die pasiëntpopulasie van Tygerberg-hospitaal te ondersoek en om ondersoek in te stel na spesifieke gasheer-patogeen interaksies van verteenwoordigende isolate. Opeenvolgende, nie-herhalende en suiwer kliniese S. aureus isolate is versamel oor ´n periode van een jaar (September 2009/2010), tesame met pasiënt demografiese- en beperkte kliniese inligting. Stamme is deur PFGE en molekulêre merkers (spa, MLST, agr, SCCmec en PVL) beskryf. Verteenwoordigende isolate is gekies en ondersoek vir die teenwoordigheid van virulensie gene, aanhegting ( aan geïmmobiliseerde fibronektien [Fn], fibrinogeen [Fg], kollageen IV [CnIV] en kollageen VI [CnVI]), sellulêre indringing en die induksie van seldood. Statistiese assosiasies is bepaal tussen alle in vitro resultate en methicillin-weerstandigheid, klonaliteit, pasiënt MIV status en bakteriese PVL status. Fyftien persent van die isolate (n = 367) was MRSA. Vier-en-veertig van die isolate was PVL+. agrI-IV en SCCmec I-V is geïdentifiseer. Die MSSA bevolking was divers: ST22 (dominant), ST1865 en ST121 PVL +. ST45, ST1863 en ST15 was PVL+. PVL- MRSA was divers: ST612-MRSA-IV (dominant), ST5-MRSA-I, ST239-MRSA-III, ST36-MRSA-II en ST22-MRSA-IV. Die gene fnbA/B (fibronektien A/B), clfA/B (klontings faktor A/B), eap (ekstrasellulêre aanhegtings protein), nuc (nukease), coa (koagulase) en hld (delta toksien) was aangetref in alle verteenwoordigende isolate. Isolate van KK8 en KK6 het sterk aan alle ligande (100-700% van kontrole, ligand-afhanklike) aangeheg, terwyl isolate van KK45, KK22 en KK88 slegs sterk aand fibronektien en fibrinogeen aangeheg het. Isolate van KK30, KK15, en KK12 het baie sterk aan CnIV (> 300%) aangeheg en KK8, KK15, en KK6 and CnVI (> 200%). Isolate van KK30, KK8, KK15, KK6, KK12, KK97, KK88 en KK45 was hoogs indringend (> 100%). ST121 was nie-indringende (> 50%). Isolate van KK5, KK30 en KK121 was nie-sitotoksiese (<50%), terwyl isolate van KK22, KK8, KK15, KK45 en KK88 baie sitotoksies was (> 70%). Geen betekenisvolle verskil is waargeneem in die aanhegting of seldood induksie van MRSA teenoor MSSA klone of tussen isolate van MIV+ teenoor MIV- persone nie. PVL- isolate het hoër sellulêre indringing as PVL+ isolate vertoon. Die teenwoordigheid van ST612-MRSA-IV, ST22-MRSA-V en ST8-MRSA-V verwys na die plaaslike verwerwing van SCCmec, aangesien ons MSSA isolate beskryf het met dieselfde spa-tipes. Talle MSSA klone was algemeen, maar het nie 'n beduidende genetiese agtergrond met MRSA vertoon nie. PVL was baie algemeen onder MSSA isolate en die PVL gene is dalk onafhanklik van SCCmec verkry. Die vermoë om aan spesifieke geïmmobiliseer ligande in vitro aan te heg was divers en groepeer met die genetiese agtergrond, terwyl die meerderheid van die isolate indringend was en kon betekenisvolle sel dood veroorsaak. Ons kan aflei dat die bevolking van S. aureus by die Tygerberg hospitaal saamgestel is uit 'n groot aantal van MSSA en MRSA klone, wat verskillende patrone van aanhegting aan geselekteerde ligande vertoon en waarvan die meeste klone indringende en sitotoksies is. / DFG/NRF International Research and Training Group (IRTG) 1522 “HIV and associated infectious diseases in Southern Africa” / National Research Foundation / Medical Research Council, Medi-Clinic / Harry Crossley Fund (Stellenbosch University) / Stellenbosch University

ABSTRACT Few antibiotics are left that are effective against methicillin-resistant Staphylococcus aureus (MRSA) and even strains resistant to these agents have been isolated. Previous studies have identified five distinct MRSA clonotypes, which are present globally. No comprehensive national study has previously been undertaken to investigate the MRSA types in South Africa, and this study was aimed at elucidating the genotypic population structure of South African MRSA isolates. SmaI digested genomic DNA, separated by pulsed-field gel electrophoresis, was used to characterise 349 S. aureus isolates, obtained from various state and private diagnostic laboratories. PFGE results were complemented with those of spa typing and staphylococcal cassette chromosome mec (SCCmec) typing results. Two-hundred-and-five different PFGE patterns were identified, which were grouped into twenty-four clusters. Three were major lineages, containing more than 20% of the isolates with a similarity cut-off of 70%. Only thirty-seven spa types were identified (fourteen novel spa types), which clustered into six spa-Clonal Complexes after BURP analysis. SCCmec types I-IV were identified, including variants of each type. Data suggest that the Archaic clone (RSA05), oldest of the epidemic clones, represents one of the major clones in South Africa. Strains that were part of this complex (n=98 (28.2%); t064; SCCmec type I-pls) clustered together with strain E2125/ATCC BAA-38 (t051; SCCmec type I). Another major complex, RSA16 (n=90 (25.7%); t012; SCCmec type II/IIB) possessed a single-locus variant (SLV) spa type and the same or a SLV SCCmec types as EMRSA-16 (t018; SCCmec type II). The third major complex, RSA03 (n=74 (21.2%); t037; SCCmec type III/IIIE), had similar spa and SCCmec types to control strainANS46 (t037; SCCmec type III). One MRSA and twelve MSSA isolates were also identified as carrying genes for the toxin Panton-Valentine leukocidin, which was confirmed by DNA nucleotide sequencing.

Introdução: A problemática referente à conduta com profissionais na área de saúde colonizados por Staphylococcus aureus sensíveis e resistentes à metilcilina está em grande evidência, por ser este um importante patógeno causador de doenças com alta morbi-mortalidade.(LOWY, 1998). Atualmente as infecções por Staphylococcus aureus não respondem mais ao tratamento com os antimicrobianos anteriormente utilizados (CDC, 2006). O Staphylococcus aureus, resistente à meticilina (MRSA), vem se disseminando nos serviços de saúde e tem sido uma das causas de infecções com maior dificuldade de tratamento (CDC,1999). A maioria das infecções ocorre em pessoas colonizadas com o micro-organismo, sendo o carreador de longo tempo um fator de risco mais fortemente associado com infecção subsequente (WERTHEIM et al, 2005a). Objetivos: Avaliar a colonização e o perfil de susceptibilidade dos Staphylococcus aureus isolados na saliva da equipe de enfermagem atuante nas unidades de terapia intensiva, clínica médica, clínica cirúrgica e gineco-obstétrica de uma instituição de saúde de grande porte do interior paulista. Determinar a prevalência de portadores de Staphylococcus aureus resistentes à meticilina e à mupirocina, levando em consideração o tempo de atuação profissional, jornada no hospital e tempo de contato com os pacientes desse hospital. Métodos: Foram coletadas três amostras da saliva de 351 indivíduos, correspondendo a 94,1% dos profissionais da equipe de enfermagem com intervalo de dois meses entre as coletas. As amostras foram semeadas em agar manitol salgado e colônias típicas de Staphylococcus aureus foram identificadas pela coloração de Gram, produção de catalase, coagulase, Dnase, fermentação do manitol e o perfil de susceptibilidade determinado pelo teste de difusão de disco. Resultados: A prevalência entre os trabalhadores foi de 144 (41,0%) sendo 25 (7,1%) caracterizados como resistentes e 104 (29,6%) como sensíveis à meticilina (MSSA) 15 (4,3%) não foram recuperados para o antibiograma. Os carreadores transitórios representaram 81,2% e os persistentes 18,8%. A resistência à mupirocina foi de 73,1% entre os MRSA e 9,3% nos MSSA. Os resultados evidenciaram que os enfermeiros e técnicos de enfermagem constituem a categoria profissional mais susceptível à colonização por MRSA. O tempo na instituição não teve uma forte correlação com a colonização do profissional, pois trabalhadores com menor tempo na instituição também tiveram alta incidência de colonização. Discussão: Ao considerarmos outros fatores envolvidos como o setor de trabalho, fica evidenciado um panorama de risco para a segurança do paciente. Conclusão: Constatamos, na cavidade bucal, um potencial reservatório e fonte de disseminação de Staphylococcus aureus nos serviços de saúde, bem como um fator de risco de infecção para o trabalhador e, portanto, a necessidade de estudos específicos e intervenções para a prevenção e controle de MRSA, considerando principalmente a condição de setores especiais. / Introduction: The problem of how to manage health professionals colonized by methicillin sensitive and resistant Staphylococcus aureus is very evident, as this important pathogen causes different diseases with high morbidity and mortality rates (LOWY, 1998). Today, infections by Staphylococcus aureus no longer respond to treatment with formerly used antibiotics (CDC, 2006). Methicillin resistant Staphylococcus aureus is spreading across health services and has been one of the infection causes most difficult to treat (CDC, 1999). Most infections affect people colonized by the microorganism. Long-term carriers are a risk factor more strongly associated with subsequent infection (WERTHEIM et al, 2005a). Aims: To assess the colonization and susceptibility profile of Staphylococcus aureus isolated in the saliva of nursing teams active at the intensive care, medical clinic, surgical clinic and gynecological-obstetrical units of a large health institution in the interior of São Paulo State, Brazil. To determine the prevalence of nursing professionals carrying methicillin and mupirocin resistant Staphylococcus aureus, in view of their length of professional activity, work hours at the hospital and time of contact with hospital patients. Methods: Three saliva samples were collected from 351 individuals, corresponding to 94.1% of nursing team professionals, with a two-month interval between the collections. The samples were seeded in mannitol salt agar and typical colonies of S. aureus were identified through Gram stain; catalase, coagulase and Dnase production; mannitol fermentation and susceptibility profile determined by the disk diffusion test. Results: Prevalence levels among workers corresponded to 144 (41,0%) colonized by S aureus, 25 (7,10%) of whom were characterized as MRSA and 104 (29.6%) as methicillin sensitive Staphylococcus aureus, while 15 (4.3%) were not recovered for the antibiogram. Transitory carriers represented 81,2% and persistent carriers 18,8%. Mupirocin resistance was 73.1% among MRSA and 9.3% among MSSA. Results evidenced that nursing technicians and nurses were the professional category most susceptible to MRSA. No strong correlation was found between length of professional activity at the institution and colonization, as professionals working less time at the institution also displayed high colonization ratios. Discussion: These results are relevant for the study institution. When considering other factors involved in professional categorization and the work site, a picture of risk for patient safety is evidenced. Conclusion: Workers\' oral cavity is a potential reservoir and source of dissemination of S. aureus in health services, as well as a risk factor for infection. Hence, specific studies and MRSA prevention and control interventions are needed, mainly when considering the condition of special sectors.