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The present study aimed to assess the antimicrobial and antiadhesion behavior of quercetin-loaded chitosan nanoparticles in Escherichia coli and Staphylococcus aureus multidrug-resistant isolates.The ionic gelation method was used to prepare chitosan nanoparticles loaded with quercetin. The antimicrobial and antibiofilm effects were observed by minimum inhibitory concentration (MIC), plate count, crystal violet assay, and the matrix exopolysaccharide dosages. The nanoparticles coated in silicone urethral catheters were evaluated by crystal violet assay and plating count method.MIC ranged from 6.25 to 12.5 mg/ml. A reduction of at least 3.6 log CFU/ml and 6.2 log CFU/ml for, respectively, E. coli and S. aureus isolates was observed (p 0.05). Under subinhibitory concentration (3.1 mg/ml) it was found a reduction of microbial adhesion and exopolysaccharide dosages in respectively 83.3% and 75% of the bacterial samples. The coated silicone urethral catheters showed a reduction of adhered cells in 25% of the isolates and biomass decreasing in 91.6% of them (p 0.05).The quercetin nanoparticles provided antimicrobial and antiadhesion effects in multidrug-resistant isolates.

Staphylococcus aureus is an important pathogen associated with various infections, including foodborne outbreaks worldwide. Due to possible contamination during food preparation by food handlers, the presence of this species in kitchens environmental is a risk to global health, mainly S. aureus biofilm-producing. Moreover, there are few reports of the evaluation of biofilm production of S. aureus obtained from food handlers in Brazil. The study aimed to characterize phenotypically and genotypically biofilm production associated with ica-dependent and ica-independent genes in S. aureus isolated from food handlers in this country. A total of 74 Staphylococcus sp. strains were isolated and 37 (50%) were identified as S. aureus through the sau gene detection. All S. aureus strains exhibited a high ability to form biofilm and detected several genes involved in this process, spotlighting the icaA (86.5%), icaD (86.5%), sasG (78.7%), atlA (78.7%) and aap (78.7%). Furthermore, the predominance of biofilm-associated genes in the strong biofilm-producing isolates by TB and TCP was found, presenting a significant association between methods and genes detected (p = S. aureus biofilm-producing, triggering the transmission of this genus isolated worldwide.

OBJETIVO: Avaliar o conhecimento sobre sí­filis em idosos no municí­pio de ílvares Machado - SP e caracterizar os aspectos sociodemográficos dessa população. MÉTODO: Estudo transversal, onde foram incluí­dos idosos residentes em ílvares Machado. Coletou-se informações pessoais, comportamentais, perfil sócio demográfico e comportamento sexual. A análise estatí­stica foi a descritiva simples e a associação entre as variáveis de interesse, utilizou-se o teste qui quadrado ou exato de Fisher. RESULTADOS: Todos idoso eram heterossexuais (100%). Houve prevalência de idosos que não utilizam preservativos (62,63%) e apenas (18,18%) dos entrevistados entendem a sí­filis como uma infecção sexualmente transmissí­vel e (15,15%) relataram como se previne a doença. CONCLUSíO: Existe um despreparo e desinformação dos idosos quanto a sua saúde sexual e esses idosos não têm conhecimento sobre a sí­filis, sua manifestação e prevenção.

A leucorreia representa uma das queixas mais recorrentes entre as mulheres, principalmente em idade fértil. A vaginose bacteriana é a mais prevalente, sendo uma síndrome multifatorial com redução do número de lactobacilos e aumento de cepas potencialmente patogênicas. O objetivo deste estudo foi avaliar se há correlação entre o diagnóstico clínico e o exame a fresco. Foram avaliadas 22 pacientes com queixa sugestiva de vaginose bacteriana, triadas pelo odor fétido. As etapas da pesquisa foram: anamnese, exame físico, medida do pH vaginal, teste das aminas e exame a fresco. Os critérios de Amsel foram utilizados no diagnóstico de vaginose bacteriana. Os resultados evidenciaram a vaginose bacteriana como o distúrbio ginecológico mais prevalente. Houve concordância entre o diagnóstico clínico e o exame a fresco em 15 casos e discordância em 7. Foi possível observar que a microscopia direta teve fundamental importância no diagnóstico diferencial, já que há alterações que mimetizam outra.

This study aimed at detecting Staphylococcus aureus from white coats of college students and characterizing antimicrobial susceptibility and biofilm production. Bacterial samples (n = 300) were obtained from white coats of 100 college students from August 2015 to March 2017 S. aureus was isolated and it´s resistance profile was assessed by antimicrobial disk-diffusion technique, screening for methicillin-resistant Staphylococcus aureus (MRSA), detection of mecA gene by PCR, and determination of staphylococcal cassette chromosome mec (SCCmec) by multiplex PCR. Congo red agar (CRA) and icaA and icaD genes by PCR were used for biofilm characterization. S. aureus was identified in 45.0% of samples. Resistance of S. aureus sample to antimicrobial was seen for penicillin (72.59%), erythromycin (51.85%), cefoxitin (20.74%), oxacillin (17.04%), clindamycin (14.81%) and levofloxacin (5.18%). MRSA was detected in 53.3% of the samples with SCCmec I (52.8%), SCCmec III (25%) and SCCmec IV (11.1%). Biofilm production was observed in 94.0% S. aureus samples. These data show that biosafety measures need to be enhanced in order to prevent dissemination of multiresistant and highly adhesive bacteria across other university settings, relatives, and close persons.

Introduction Escherichia coli is a Gram-negative opportunistic human pathogen, which has aroused considerable medical interest for being involved in cases of urinary tract infection. Aim Characterize the E. coli isolated both in the hospital and in the community. Methodology A total of 200 E. coli isolated in urine samples from hospital and community were evaluated in biofilm formation assay and hydrophobicity MATS method. Antimicrobial susceptibility was performed through agar-diffusion technique. Virulence and ESBL production genes were observed through the polymerase chain reaction amplification of papC, fimH, fliC, kpsMTII, blaTEM, blaCTX-M, blaSHV , and blaOXA. The phylogenetic classification was based on the pattern chuA and yjaA and the region TspE4.C2 by PCR Multiplex. Results A higher frequency of non-adherent or poorly adherent isolates was observed in the community group. Approximately 85% of the community isolates were distributed in the highest hydrophilicity group (p 0.05). About 14% of the hospital isolates were positive in the ESBL phenotypic detection test (p>0.05). Among the samples, 95% presented ESBL-encoding genes. The predominant phylogenetic group was B2 (78%). Community isolates showed a higher prevalence of virulence genes fimH, papC, and kpsMTII when compared to hospital samples. Conclusion These data confirm the worldwide trend that isolates in the community present sometimes higher levels of virulence and antimicrobial resistance.

Staphylococcus aureus and coagulase-negative staphylococci (CoNS) have become the main causative agents of medical device-related infections due to their biofilm-forming capability, which protects them from the host’s immune system and from the action of antimicrobials. This study evaluated the ability of RNA III inhibiting peptide (RIP) to inhibit biofilm formation in 10 strains isolated from clinical materials, including one S. aureus strain, two S. epidermidis, two S. haemolyticus, two S. lugdunensis, and one isolate each of the following species: S. warneri, S. hominis, and S. saprophyticus. The isolates were selected from a total of 200 strains evaluated regarding phenotypic biofilm production and the presence and expression of the ica operon. The isolates were cultured in trypticase soy broth with 2% glucose in 96-well polystyrene plates containing catheter segments in the presence and absence of RIP. The catheter segments were observed by scanning electron microscopy. The results showed inhibition of biofilm formation in the presence of RIP in all CoNS isolates, however, RIP did not interfere with biofilm formation by S. aureus. RIP is a promising tool that might be used in the future for the prevention of biofilm-related infections caused by CoNS.

Made available in DSpace on 2021-06-25T12:39:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01. Added 1 bitstream(s) on 2021-07-15T14:36:34Z : No. of bitstreams: 1 S0036-46652021000100208.pdf: 315461 bytes, checksum: 46e0bb1594d398e0f052e0429b6d98da (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nasal carriage of Staphylococcus aureus by healthcare workers is of great clinical importance as it facilitates the contamination of medical devices and cross-transmission. However, studies regarding the epidemiology and dissemination of S. aureus and Methicillin-resistant S. aureus (MRSA) within the Primary Health Care in Brazil are scarce. The current study aimed to detect and characterize S. aureus and MRSA strains from the nasal cavities of 63 healthcare working in primary health care units in order to determine the prevalence of S. aureus and MRSA, biofilm formation and resistance profile of these isolates. PCR reactions were performed for detecting mecA, icaA and ical) genes. The phenotypic antimicrobial susceptibility was assessed by the disk diffusion method and biofilm formation by the Congo Red Agar (CRA) method. The MRSA isolates were typed for the Staphylococcal Cassette Chromosome mec (SCCmec). The prevalence of nasal carriage of S. aureus was 74.6%. of which 72.3% were MRSA carrying SCCmec type I (24.4%), III (34.1%), IV (36.6%). Two (4.9%) isolates presented a non-typeable cassette by the performed technique. The antimicrobial susceptibility evaluation evidenced penicillin resistance in 66.1% of S. aureus, erythromycin resistance in 49.2%. while 37.3% were resistant to oxacillin, 28.8% to cefoxitin, 5.1% to levofloxacin and 5.1% to clindamycin. All isolates were biofilm producers and 96.6% of the strains contained the ica biofilm-forming genes (icaA and/or ical)). We have demonstrated a high prevalence of S. aureus and MRSA carriage among health care working in Primary health Care units, the presence of SCCmec types I, III and IV, in addition to their high ability to form biofilm, factors that possibly contribute to the dissemination and persistence of these pathogens within the primary care services. These observations highlight the importance of broadening the perspective of Health Care-Associated Infections prevention, including all health care levels, which are currently little explored. In addition, the dynamics and resistance mechanisms of S. aureus transmission still need to be further clarified to enable the implementation of more effective prevention measures. Univ Oeste Paulista, Rua Jose Bongiovani 700, BR-19050920 Presidente Prudente, SP, Brazil Univ Estadual Paulista, Dept Ciencias Quim & Biol, Botucatu, SP, Brazil Inst Lauro Souza Lima, Dept Patol, Bauru, SP, Brazil Univ Estadual Paulista, Dept Ciencias Quim & Biol, Botucatu, SP, Brazil FAPESP: 2017/01104-5

Microbial biofilms are communities of cells adhered to a surface embedded with a matrix of polymeric extracellular substances. The biofilm can present one or more species of microorganisms, depending on its duration and location. It may involve Gram-positive, Gram-negative bacteria and yeast such as Candida albicans, Coagulase negative Staphylococcus, Enterococcus spp., Klebsiela pneumoniae, Pseudomonas aeruginosa and Staphylococccus aureus. In addition to bacteria, other cellular elements may be aggregated in the biofilm, such as platelets, for example, when the biofilm is installed on a surface bathed in blood. In the health area, there are a variety of possible situations that allow biofilm formation in medical devices directly connected to the patient or indirectly by contamination of the machines or pipes of that environment. Biofilm formation has been linked to 60% of hospital infections. In this way, components and methods that can inhibit the biofilm formation or even dissolve it have been investigated. Nanobiotechnology is an area of nanotechnology related to the creation, use and improvement of nanostructures in biotechnological processes. Among the various research fields in this area is the synthesis, characterization and application of nanoparticles with different sizes, shapes and chemical compositions. The traditional methods used for the synthesis of these nanoparticles are generally chemical methods in which toxic solvents are used and the generation of dangerous by-products can occur and involve high energy consumption. Due to these factors, there is an increasing need to develop non-toxic and environmentally friendly procedures; but with a high yield and low cost. In this context, the routes of synthesis of nanoparticles by biological systems, also known as green synthesis or biosynthesis, become quite relevant. This chapter addresses the perspectives by which green synthesis nanoparticles can be integrated as an effective method of control and prevention of microbial biofilms.

The ability of Staphylococcus epidermidis to produce virulence factors, such as biofilm, added to its increased resistance to antimicrobials can cause infections that are difficult to treat. Many staphylococcal virulence factors are under the control of the accessory gene regulator (agr). The objective of this study was to establish the agr locus and susceptibility of biofilm-producing S. epidermidis specimens to antimicrobial agents, through PCR reactions, reverse transcription polymerase chain reaction (RT-PCR), and the determination of minimum inhibitory concentration (MIC), and to analyze the clonal profile of 300 strains isolated from blood culture specimens from inpatients at a University Hospital in Brazil, over a 20-year period by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) techniques. The ica operon expression was shown in 83.6% strains, bhp gene in 11.5%, and aap gene in 32.8%. Oxacillin resistance was detected in 90.1%, while 4.9% showed tigecycline resistance, and intermediate resistance to quinupristin/dalfopristin was identified in 0.4%. Clonal profile determination showed 11 clusters, with the ST2 type determined as the major cluster. The S. epidermidis biofilm producer demonstrated a predominance of agr I locus, oxacillin resistance, and SCCmec III as well as the potential dissemination of pathogenic clones in hospital settings over long periods.

Made available in DSpace on 2020-12-12T01:58:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01. Added 1 bitstream(s) on 2021-07-15T15:07:25Z : No. of bitstreams: 1 S1413-86702020000200160.pdf: 1344439 bytes, checksum: 135638b8bb24404758692d2dd53e85f4 (MD5) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The increasing rates of nosocomial infection associated with coagulase–negative staphylococci (CoNS) were the rationale for this study, aiming to categorize oxacillin–resistant CoNS species recovered from blood culture specimens of inpatients at the UNESP Hospital das Clínicas in Botucatu, Brazil, over a 20–year period, and determine their sensitivity to other antimicrobial agents. The mecA gene was detected in 222 (74%) CoNS samples, and the four types of staphylococcal chromosomal cassette mec (SCCmec) were characterized in 19.4%, 3.6%, 54.5%, and 14.4% of specimens, respectively, for types I, II, III, and IV. Minimal inhibitory concentration (MIC) values to inhibit 50% (MIC50) and 90% (MIC90) of specimens were, respectively, 2 and >256 μL/mL for oxacillin, 1.5 and 2 μL/mL for vancomycin, 0.25 and 0.5 μL/mL for linezolid, 0.094 and 0.19 μL/mL for daptomycin, 0.19 and 0.5 μL/mL for quinupristin/dalfopristin, and 0.125 and 0.38 μL/mL for tigecycline. Resistance to oxacillin and tigecycline and intermediate resistance to quinupristin/dalfopristin were observed. Eight (2.7%) of all 300 CoNS specimens studied showed reduced susceptibility to vancomycin. Results from this study show high resistance rates of CoNS to antimicrobial agents, reflecting the necessity of using these drugs judiciously and controlling nosocomial dissemination of these pathogens. UNESP-Universidade Estadual Paulista Instituto de Biociências de Boucatu Departamento de Microbiologia e Imunologia UNOESTE-Universidade Oeste Paulista Departamento de Microbiologia UNESP-Universidade Estadual Paulista Instituto de Biociências de Boucatu Departamento de Microbiologia e Imunologia

O presente estudo teve por objetivo determinar a eficácia, efetividade e segurança do Remdesivir no tratamento para a Covid-19 através de uma revisão integrativa. A busca dos artigos foi realizada em março de 2021 nas bases de dados Pubmed, Scielo, Embase e Cochrane. Para guiar essa pesquisa, levantou-se a questão norteadora: “Qual o papel do Remdesivir no tratamento da Covid-19 em humanos?”. Foram utilizados os descritores “Covid ou Sars-Cov-2 ou Coronavirus” e “treatment” e “Remdesivir”. Os critérios de inclusão foram estudos primários originais que abordassem o tema proposto, disponíveis na integra, entre 2019-2021, nos idiomas português ou inglês. Dos 3012 artigos encontrados, foram utilizados 17 que atenderam os critérios de inclusão. A maioria dos estudos encontrados relatou uma melhora no quadro dos pacientes tratados com Remdesivir, porém é importante ressaltar que a terapia com o medicamento também apresentou diversos efeitos colaterais e não alterou o índice de mortalidade. Com base nos dados analisados, o Remdesivir demonstrou resultados promissores, sugerindo um perfil de risco-benefício favorável, porém até onde se foi observado, a tava de óbitos não foi alterada e seu uso prolongado pode desencadear efeitos colaterais indesejáveis.

Made available in DSpace on 2018-12-11T17:03:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01 The aim of this study was to evaluate the antimicrobial susceptibility profile of 85 Staphylococcus epidermidis and 84 Staphylococcus haemolyticus strains isolated from blood cultures to oxacillin, vancomycin, tigecycline, linezolid, daptomycin, and quinupristin/dalfopristin over a period of 12 years. S. epidermidis and S. haemolyticus isolated from blood cultures of inpatients, attended at a teaching hospital, were analyzed for the presence of the mecA gene and by SCCmec typing. The minimum inhibitory concentration (MIC) values of tigecycline, linezolid, daptomycin, quinupristin/dalfopristin, and vancomycin were determined. Isolates exhibiting vancomycin MICs of ≥2 μg/ml were typed by pulsed-field gel electrophoresis (PFGE). The rate of mecA positivity was 92.9% and 100% in S. epidermidis and S. haemolyticus, respectively. The most frequent SCCmec types were type III (53.2%) in S. epidermidis and type I (32.1%) in S. haemolyticus. All isolates were susceptible to linezolid and daptomycin, but 7.1% of S. haemolyticus and 2.3% of S. epidermidis isolates were resistant to tigecycline, and 1.2% each of S. haemolyticus and S. epidermidis were resistant and intermediately resistant to quinupristin/dalfopristin, respectively. S. epidermidis exhibited higher vancomycin MICs (40% with MIC of ≥2 μg/ml). Clonal typing of strains with vancomycin MIC of ≥2 μg/ml revealed the presence of different PFGE types of S. epidermidis and S. haemolyticus over a period of up to 4 years (2002-2004, 2005-2008, 2006-2009, 2010-2011). Despite the observation of a high prevalence of mecA, the clinical strains were fully susceptible to vancomycin and to the new drugs linezolid, daptomycin, tigecycline, and quinupristin/dalfopristin. The PFGE types with vancomycin MIC of ≥2 μg/ml exhibited a great diversity of SCCmec cassettes, demonstrating that S. epidermidis and S. haemolyticus may easily acquire these resistance-conferring genetic elements. Departamento de Microbiologia e Imunologia Instituto de Biociências Universidade Estadual Paulista (UNESP), Distrito de Rubião Jr. s/n Nucleo de Doencas Entericas e Infeccoes Por Patogenos Especiais Centro de Bacteriologia Instituto Adolfo Lutz São Paulo Departamento de Microbiologia e Imunologia Instituto de Biociências Universidade Estadual Paulista (UNESP), Distrito de Rubião Jr. s/n

Background The hospital environment is susceptible to bacterial contamination along with survival in fomites and surfaces, allowing dissemination of potential pathogenic strains. The present research aimed to evaluate the influence of biological fluids in bacterial viability on fomites and surfaces commonly present in nosocomial environment. Methods Four different fomites and surfaces (ceramic floor, cotton fabric fragments and synthetic fibers, and eggcrate foam mattress) were contaminated with potential pathogens ( Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa , and Klebsiella pneumoniae ), then submitted to influence of biological fluids (blood, urine, artificial saliva). The viability of strains was evaluated at 24 hours after contamination and then in intervals of 7 days, by the colony-forming unit count technique. Results S aureus presented viability (>70 days) in all conditions tested, E faecalis and K pneumoniae had decreased viability over time, and E coli did not exhibit a growth relationship with surfaces or fluids. Persistence and adaptability capacity of potential pathogens in fomites and surfaces exposed to the patient are important for guidance, planning, and outlining of protocols for microorganism dissemination control and prevention in the health care environment.

Several studies demonstrate that dairy products are the main foodstuffs that employ probiotic bacteria in their composition. The main objective of this study was to characterize the CE51 isolate as a potential probiotic strain and also develop and evaluate the viability of probiotic orange juice drink. In total, 152 lactic acid bacteria were isolated from food samples. The bacteriocin-like substance producing isolate was sequenced by 16S rDNA. Probiotic potential was evaluated by survival in de Man Rogosa Sharpe broth in pH 2.0, 2.5, and 3.5 and in the presence of bile salts (0.3, 0.6, and 0.9%) for up to 180 min. Probiotic orange juice was developed at pH4.5 and pH6.5 with an initial inoculum of 106 CFU/ml. The juices were stored at 4 °C and 30 °C for up to 35 days. Only one isolate presented antimicrobial activity against Listeria monocytogenes which was genetically identified as Pediococcus acidilactici CE51. The probiotic potential was confirmed by its resistance to acid pH and bile salts presence. The two probiotic juice formulations presented counts between 7.2 and 8.5 log CFU/ml after 35 days at 4 °C and 30 °C. Therefore, orange juice could act as an ideal food matrix for probiotic beverage of Pediococcus acidilactici CE51.

Made available in DSpace on 2019-10-06T16:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Bacterial biofilms play an important role in urinary tract infections (UTIs), being responsible for persistent infections that lead to recurrences and relapses. Staphylococcus saprophyticus is one of the main etiological agents of UTIs, however, little is known about biofilm production in this species and especially about its response to the antimicrobial agents used to treat UTIs when a biofilm is present. For this reason, the aim of this work was to evaluate the response of S. saprophyticus biofilms to five antimicrobial agents. Staphylococcus saprophyticus was evaluated for antimicrobial susceptibility in its planktonic form by means of minimum inhibitory concentration (MIC) and in biofilms by means of minimum inhibitory concentration in biofilm (MICB) against the following antimicrobial agents by the microdilution technique: Vancomycin, oxacillin, trimethoprim/sulfamethoxazole, ciprofloxacin, and norfloxacin. Of the 169 S. saprophyticus studied, 119 produced a biofilm as demonstrated by the polystyrene plate adherence method. Biofilm cells of S. saprophyticus exhibited a considerable increase in MICB when compared to the planktonic forms, with an increase of more than 32 times in the MICB of some drugs. Some isolates switched from the category of susceptible in the planktonic condition to resistant in the biofilm state. Statistical analysis of the results showed a significant increase in MICB (p < 0.0001) for all five drugs tested in the biofilm state compared to the planktonic form. Regarding determination of the minimum bactericidal concentration in biofilm (MBCB), there were isolates for which the minimum bactericidal concentration of all drugs was equal to or higher than the highest concentration tested. Department of Microbiology and Immunology Institute of Biosciences UNESP - Universidade Estadual Paulista Department of Tropical Diseases Botucatu School of Medicine University Hospital UNESP - Universidade Estadual Paulista Department of Microbiology and Immunology Institute of Biosciences UNESP - Universidade Estadual Paulista Department of Tropical Diseases Botucatu School of Medicine University Hospital UNESP - Universidade Estadual Paulista

Made available in DSpace on 2015-08-26T19:19:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-01. Added 1 bitstream(s) on 2015-08-31T13:04:46Z : No. of bitstreams: 1 S1517-83822015000200535.pdf: 774594 bytes, checksum: eb7a895cff0c3bf9a22909d136c7769e (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The objective of this study was to characterize the clonal profile, virulence factors and antimicrobial resistance, particularly oxacillin resistance, of Staphylococcus aureus isolated from sheep milk. Milk samples were collected from all teats for the California Mastitis Test (CMT), somatic cell count, identification of S. aureus, investigation in these strains of genes encoding toxins (sea, seb, sec, sed, tst), biofilm (icaA, icaC, icaD, bap), leukocidin (luk-PV) oxacillin resistance by mecA gene detection and susceptibility testing (12 antibiotics). Messenger RNA expression was evaluated by RT-PCR in isolates carrying toxin and biofilm genes. Biofilm formation was also evaluated phenotypically by adherence to polystyrene plates. The clonal profile of S. aureus was investigated by pulsed-field gel electrophoresis. A total of 473 milk samples were collected from 242 animals on three farms and 20 S. aureus strains were isolated and none carried the mecA gene. The two sec gene-positive isolates and the isolates carrying the tst and luk-PV genes were positive by RT-PCR. Staphylococcus aureus isolated from the three flocks studied showed high susceptibility to the drugs tested and none was biofilm producer, indicating that biofilm formation was not a virulence factor causing infection by these strains. The typing of 17 S. aureus isolates revealed the presence of a common clone on the three farms studied, and the presence and expression of the sec and tst genes in one strain of this clone suggest the possible acquisition of virulence genes by this clone, a fact that is important for animal health and food hygiene. Universidade Estadual Paulista Instituto de Biociências Departamento de Microbiologia e Imunologia Universidade Estadual Paulista Faculdade de Medicina Veterinária e Zootecnia Departamento de Produção Animal Embrapa Pecuária Sudeste Universidade Estadual Paulista Instituto de Biociências Departamento de Microbiologia e Imunologia Universidade Estadual Paulista Faculdade de Medicina Veterinária e Zootecnia Departamento de Produção Animal

Made available in DSpace on 2014-10-01T13:08:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-11-01Bitstream added on 2014-10-01T14:03:54Z : No. of bitstreams: 1 S0074-02762013000700939.pdf: 359627 bytes, checksum: 8eb1b6a12bdbdbc32068b9555e1e7321 (MD5) Coagulase-negative staphylococci (CoNS) are the microorganisms most frequently isolated from clinical samples and are commonly found in neonatal blood cultures. Oxacillin is an alternative treatment of choice for CoNS infections; however, resistance to oxacillin can have a substantial impact on healthcare by adversely affecting morbidity and mortality. The objective of this study was to detect and characterise oxacillin-resistant CoNS strains in blood cultures of newborns hospitalised at the neonatal ward of the University Hospital of the Faculty of Medicine of Botucatu. One hundred CoNS strains were isolated and the mecA gene was detected in 69 of the CoNS strains, including 73.2% of Staphylococcus epidermidis strains, 85.7% of Staphylococcus haemolyticus strains, 28.6% of Staphylococcus hominis strains and 50% of Staphylococcus lugdunensis strains. Among these oxacillin-resistant CoNS strains, staphylococcal cassette chromosome mec (SCCmec) type I was identified in 24.6%, type II in 4.3%, type III in 56.5% and type IV in 14.5% of the strains. The data revealed an increase in the percentage of CoNS strains isolated from blood cultures from 1991-2009. Furthermore, a predominant SCCmec profile of the oxacillin-resistant CoNS strains isolated from neonatal intensive care units was identified with a prevalence of SCCmec types found in hospital-acquired strains. Universidade Estadual Paulista Instituto de Biociencias Departamento de Microbiologia e Imunologia Universidade Estadual Paulista Instituto de Biociencias Departamento de Microbiologia e Imunologia

Made available in DSpace on 2018-12-11T17:16:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Infections with coagulase-negative staphylococci (CoNS) can involve the production of toxins such as superantigens, which contribute to tissue degradation and inflammatory immune responses. The accessory gene regulator (agr) quorum sensing system coordinates the expression of most S. aureus virulence factors. Therefore, the aim of this study was to investigate the expression of these superantigens and the presence of the agr locus in CoNS strains isolated from blood cultures. PCR was used to detect enterotoxin and agr genes and expression was analyzed by RT-PCR. Expression of the sea gene was observed in one S. epidermidis isolate andof sec-1 in two, seg and sei were expressed concomitantly in one isolate, and sei was expressed in another isolate. The agr group I was detected in S. epidermidis expressing the sea, seg and sei genes, whereas agr group II was detected in isolates expressing thesec-1 gene. The agr groups were only expressed in strains expressing thesec-1 gene. The results show that enterotoxin genes are highly frequent in CoNS isolated from clinical specimens and confirm the toxin-producing ability of these strains. The agr group II may be associated with enterotoxin C production by S. epidermidis, increasing the virulence of strains isolated from blood cultures and consequently the severity of sepsis caused by these organisms. Laboratory of Bacteriology Department of Microbiology and Immunology Institute of Biosciences UNESP - Univ. Estadual Paulista Universidade do Oeste Paulista Laboratory of Bacteriology Department of Microbiology and Immunology Institute of Biosciences UNESP - Univ. Estadual Paulista FAPESP: 2011/23746-2 CNPq: 470649/2011-9

Made available in DSpace on 2018-12-11T17:05:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-09-01 The objective of the present study was to determine the antimicrobial resistance profile of planktonic and biofilm cells of Staphylococcus aureus and coagulase-negative staphylococci (CoNS). Two hundred Staphylococcus spp. strains were studied, including 50 S. aureus and 150 CoNS strains (50 S. epidermidis, 20 S. haemolyticus, 20 S. warneri, 20 S. hominis, 20 S. lugdunensis, and 20 S. saprophyticus). Biofilm formation was investigated by adherence to polystyrene plates. Positive strains were submitted to the broth microdilution method to determine the minimum inhibitory concentration (MIC) for planktonic and biofilm cells and the minimal bactericidal concentration for biofilm cells (MBCB). Forty-nine Staphylococcus spp. strains (14 S. aureus, 13 S. epidermidis, 13 S. saprophyticus, 3 S. haemolyticus, 1 S. hominis, 3 S. warneri, and 2 S. lugdunensis) were biofilm producers. These isolates were evaluated regarding their resistance profile. Determination of planktonic cell MIC identified three (21.4%) S. aureus strains that were resistant to oxacillin and six (42.8%) that were resistant to erythromycin. Among the CoNS, 31 (88.6%) strains were resistant to oxacillin, 14 (40%) to erythromycin, 18 (51.4%) to gentamicin, and 8 (22.8%) to sulfamethoxazole/trimethoprim. None of the planktonic isolates were resistant to vancomycin or linezolid. MICs were 2-, 4-, 8-, and up to 16-fold higher for biofilm cells than for planktonic cells. This observation was more common for vancomycin and erythromycin. The MBCB ranged from 8 to >256 μg/mL for oxacillin, 128 to >128 μg/mL for vancomycin, 256 to >256 μg/mL for erythromycin and gentamicin, >64 μg/mL for linezolid, and 32/608 to >32/608 μg/mL for sulfamethoxazole/trimethoprim. The results showed considerably higher MICs for S. aureus and CoNS biofilm cells compared to planktonic cells. Analysis of MBCM confirmed that even high concentrations of vancomycin were unable to eliminate the biofilms of S. aureus and CoNS species. Linezolid was the most effective drug in inhibiting staphylococci in the biofilm, without an increase in the MIC, when compared to planktonic cells. None of the isolates were resistant to this drug. Departamento de Microbiologia e Imunologia Instituto de Biociências UNESP—Univ Estadual Paulista Rua Professor Doutor Antonio CelsoWagner Zanin, s/n, Botucatu Departamento de Anatomia Patológica Instituto Lauro de Souza Lima Departamento de Microbiologia e Imunologia Instituto de Biociências UNESP—Univ Estadual Paulista Rua Professor Doutor Antonio CelsoWagner Zanin, s/n, Botucatu

Staphylococcus aureus can cause a variety of infections due to its high transmissibility, high pathogenic potential and resistance to multiple drugs, factors that contribute to the relevance of infections in healthcare services. The aim of this study was to document phenotypic and genotypic resistance factors of Staphylococcus aureus strains, isolated from nasal mucosa of medical students. A nasal swab was collected from the nares (nostrils) of 222 medical students. After collection, the samples were submitted to isolation and identification procedures. From 204 valid samples, 20.6% (42 samples) were positive for S. aureus. For the assessment of phenotypic resistance by disk-diffusion technique, from 42 samples, 95.2% showed resistance to erythromycin, 42.8% to clindamycin, 16.6% to cephoxitin and 9.5% to oxacillin. The D test showed that 26.2% of samples were resistant to macrolides, lincosamides and streptogramin B. A PCR assay allowed for the evaluation of a genotypic resistance profile, in which 16.6% of the samples were positive for the mecA gene, 35.7% positive for the ermC gene or ermA gene and 28.5% were positive for both genes. These results demonstrate that medical students can enter the healthcare service previously colonized by multidrug resistant strains and become potential spreaders in the hospital environment.

Made available in DSpace on 2018-12-11T17:06:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-09-01 Infections with coagulase-negative staphylococci are often related to biofilm formation. This study aimed to detect biofilm formation and biofilm-associated genes in blood culture isolates of Staphylococcus epidermidis and S. haemolyticus. Half (50.6%) of the 85 S. epidermidis isolates carried the icaAD genes and 15.3% the bhp gene, while these numbers were 42.9% and 0 for S. haemolyticus, respectively. According to the plate test, 30 S. epidermidis isolates were biofilm producers and 40% of them were strongly adherent, while only one (6%) of the 17 S. haemolyticus biofilm-producing isolates exhibited a strongly adherent biofilm. The concomitant presence of icaA and icaD was significantly associated with the plate and tube test results (P ≤ 0.0004). The higher frequency of icaA in S. epidermidis and of icaD in S. haemolyticus is correlated with the higher biofilm-producing capacity of the former since, in contrast to IcaD, IcaA activity is sufficient to produce small amounts of polysaccharide. Although this study emphasizes the importance of icaAD and bhp for biofilm formation in S. epidermidis, other mechanisms seem to be involved in S. haemolyticus. Departamento de Microbiologia e Imunologia Instituto de Biociências Universidade Estadual Paulista UNESP Laboratório de Patologia Instituto Lauro de Souza Lima Departamento de Microbiologia e Imunologia Instituto de Biociências Universidade Estadual Paulista UNESP

Aims: The objective of this study was to investigate the detection of SEE, SEG, SEH and SEI in strains of Staphylococcus aureus and coagulase-negative staphylococci (CNS) using RT-PCR. Methods and Results: In this study, 90 Staph. aureus strains and 90 CNS strains were analysed by PCR for the detection of genes encoding staphylococcal enterotoxins (SE) E, G, H and I. One or more genes were detected in 54 (60%) Staph. aureus isolates and in 29 (32·2%) CNS isolates. Staphylococcus epidermidis was the most frequently isolated CNS species (n = 64, 71·1%), followed by Staphylococcus warneri (n = 8, 8·9%) and other species (Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus lugdunensis, Staphylococcus simulans, Staphylococcus saprophyticus and Staphylococcus xylosus: n = 18, 20%). The genes studied were detected in Staph. epidermidis, Staph. warneri, Staph. haemolyticus, Staph. hominis, Staph. simulans and Staph. lugdunensis. The highest frequency of genes was observed in Staph. epidermidis and Staph. warneri, a finding indicating differences in the pathogenic potential between CNS species and highlighting the importance of the correct identification of these micro-organisms. RT-PCR used for the detection of mRNA revealed the expression of SEG, SEH and/or SEI in 32 (59·3%) of the 90 Staph. aureus isolates, whereas expression of some of these genes was observed in 10 (34·5%) of the 90 CNS isolates. Conclusions: Staphylococcus epidermidis was the most toxigenic CNS species. Among the other species, only Staph. warneri and Staph. lugdunensis presented a positive RT-PCR result. PCR was efficient in confirming the toxigenic capacity of Staph. aureus and CNS. Significance and Impact of the Study: This study permitted to confirm the toxigenic capacity of CNS to better characterize the pathogenic potential of this group of micro-organisms. In addition, it permitted the detection of SEG, SEH and SEI, enterotoxins that cannot be detected by commercially available immunological methods.

Staphylococcus spp. are frequently found in hospital environments and are associated with a wide variety of infections. Various virulence factors are responsible for the pathogenicity of staphylococci, among which staphylococcal enterotoxins and TSST-1 (toxic-shock syndrome) are noteworthy. In this study, 90 samples of Staphylococcus aureus and 90 samples of coagulase-negative staphylococci (CNS) isolated from different clinical materials were investigated by polymerase chain reaction (PCR) in order to study the genes encoding staphylococcal toxins A (sea), B (seb), C (sec-1), D (sed) and TSST-1(tst). The samples shown to be positive for the presence of one or more genes were tested for their capacity to express mRNA encoding the respective toxins by reverse transcription-PCR (RT-PCR). As regards the CNS species, S. epidermidis was the most frequently isolated, corresponding to 71.1% of the total number of samples of CNS investigated. One hundred and eight samples were positive according to PCR, of which 59 (54.6%) were S. aureus and 49 (45.4%) were CNS. S. aureus showed toxigenic genes for all classes of toxins investigated whereas CNS showed all genes except for that of toxin D. Assessment of mRNA expression by RT-PCR showed 43 positive samples, 37 (86.0%) S. aureus samples producing SEA, SEB, SEC, SED and/or TSST-1 and six (14.0%) CNS samples producing SEA and SEC. RT-PCR and sequencing of PCR products confirmed the toxigenic capacity of S. epidermidis and S. lugdunensis, indicating the need for greater attention to such microorganisms when they are isolated from infectious processes.

Background: Oxacillin is the main drug used for the treatment of Staphylococcus aureus infections. However, resistance of S. aureus to oxacillin has become a major problem over recent decades. The aim of this study was to determine oxacillin resistance in S. aureus isolates obtained from the University Hospital of the Botucatu Medical School, Universidade Estadual Paulista, Brazil. Materials and Methods: A total of 102 isolates collected between 2002 and 2006 were analyzed by detection of the mecA gene, cefoxitin and oxacillin disk diffusion methods, screening test on Mueller-Hinton agar and E-test. Results: Forty-six (45.1%) isolates were mecA positive. The oxacillin disk diffusion method showed 86.9% sensitivity and 91.1% specificity. The screening method and cefoxitin disk diffusion presented a similar sensitivity (91.3%) and the same specificity. The E-test showed 97.8% sensitivity and the same specificity as observed for the other methods. Conclusions: The E-test yielded the best results compared to the other methods.

Made available in DSpace on 2015-12-07T15:29:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2009. Added 1 bitstream(s) on 2015-12-07T15:53:24Z : No. of bitstreams: 1 PMC3676290.pdf: 2296332 bytes, checksum: c9958483933aa4a9fbf5779aeed5c26f (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) To determine, by phenotypic and genotypic methods, oxacillin susceptibility in Staphylococcus aureus strains isolated from pediatric and neonatal intensive care unit patients seen at the University Hospital of the Botucatu School of Medicine. A total of 100 S. aureus strains isolated from the following materials were studied: 25 blood cultures, 21 secretions, 12 catheters, 3 cannulae and one chest drain from 62 patients in the neonatal unit, and 36 blood cultures, one pleural fluid sample and one peritoneal fluid sample from 38 patients in the pediatric unit. Resistance of the S. aureus isolates to oxacillin was evaluated by the disk diffusion method with oxacillin (1 μg) and cefoxitin (30 μg), agar screening test using Mueller-Hinton agar supplemented with 6 μg/ml oxacillin and 4% NaCl, and detection of the mecA gene by PCR. In addition, the isolates were tested for β-lactamase production using disks impregnated with Nitrocefin and hyperproduction of β-lactamase using amoxicillin (20 μg) and clavulanic acid (10 μg) disks. Among the 100 S. aureus strains included in the study, 18.0% were resistant to oxacillin, with 16.1% MRSA being detected in the neonatal unit and 21.0% in the pediatric unit. The oxacillin (1 μg) and cefoxitin (30 μg) disk diffusion methods presented 94.4% and 100% sensitivity, respectively, and 98.8% specificity. The screening test showed 100% sensitivity and 98.8% specificity. All isolates produced β-lactamase and one of these strains was considered to be a hyperproducer. The 30 μg cefoxitin disk diffusion method presented the best result when compared to the 1 μg oxacillin disk. The sensitivity of the agar screening test was similar to that of the cefoxitin disk diffusion method and higher than that of the oxacillin disk diffusion method. We observed variations in the percentage of oxacillin-resistant isolates during the study period, with a decline over the last years which might be related to improved nosocomial infection control and the rational use of antibiotics. Departamento de Microbiologia e Imunologia, Instituto de Biociências de Botucatu (IBB), Universidade Estadual Paulista (UNESP), Botucatu, SP, Brasil Departamento de Pediatria, Faculdade de Medicina de Botucatu (FMB), Universidade Estadual Paulista (UNESP), Botucatu, SP, Brasil Universidade Estadual Paulista, Departamento de Microbiologia e Imunologia, Instituto de Biociências de Botucatu Universidade Estadual Paulista, Departamento de Pediatria, Faculdade de Medicina de Botucatu

Although opportunistic pathogens, coagulase-negative staphylococci (CoNS), including Staphylococcus epidermidis and Staphylococcus haemolyticus, have long been regarded as avirulent organisms. The role of toxins in the development of infections caused by CoNS is still controversial. The objective of this study was to characterize the presence of enterotoxin and cytotoxin genes in S. epidermidis and S. haemolyticus isolates obtained from blood cultures. Cytotoxin genes were detected by PCR using novel species-specific primers. Among the 85 S. epidermidis and 84 S. haemolyticus isolates, 95.3% and 79.8%, respectively, carried at least one enterotoxin gene. The most frequent enterotoxin genes were sea (53.3%), seg (64.5%) and sei (67.5%). The seg gene was positively associated with S. epidermidis (p = 0.02), and this species was more toxigenic than S. haemolyticus. The hla/yidD gene was detected in 92.9% of S. epidermidis and the hla gene in 91.7% of S. haemolyticus isolates, hlb was detected in 92.9% of the S. epidermidis isolates and hld in 95.3%. Nosocomial Staphylococcus epidermidis and S. haemolyticus isolates exhibited a high toxigenic potential, mainly producing the non-classical enterotoxins seg and sei. The previously unreported detection of hla/yidD and hlb in S. epidermidis and S. haemolyticus using species-specific primers showed that these hemolysin genes differ between CoNS species and that they are highly frequent in blood culture isolates.

Made available in DSpace on 2015-03-18T15:55:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-11-07Bitstream added on 2015-03-18T16:28:31Z : No. of bitstreams: 1 WOS000346433100001.pdf: 481955 bytes, checksum: d1009843d48f9b475c4ba56c63db6d50 (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Background: Methicillin-resistant Staphylococcus aureus (MRSA) are important pathogens in neonatal and pediatric intensive care units, which can cause severe infections in hospitalized children. Detection of the mecA gene and classification of the staphylococcal cassette chromosome mec (SCCmec) permit the characterization of MRSA strains isolated from infections caused by these microorganisms. In contrast, pulsed-field gel electrophoresis (PFGE) is used to type MRSA clones. This method is commonly used to analyze the epidemiology of bacteria causing nosocomial infections. The objective of this study was to detect and characterize MRSA isolated from clinical specimens of children hospitalized in the neonatal and pediatric intensive care units of the University Hospital of the Botucatu Medical School.Methods: A total of 119 S. aureus strains were isolated from clinical specimens and the mecA gene was detected by PCR. SCCmec was detected by multiplex PCR and the clonal profile was analyzed by PFGE.Results: The mecA gene was detected in 17.6% (21/119) of the isolates; 42.9% (9/21) of MRSA were characterized as SCCmec type III and 57.1% (12/21) as type IV. Analysis of the clonal profile of these strains revealed three distinct clones, with SCCmec type III being related to the Brazilian endemic clone and type IV to clones JCSC4469 and USA800.Conclusions: Replacement of clonal groups occurred in the neonatal and pediatric units over the period studied, a fact highlighting the importance of improving hygiene practices and control measures of nosocomial infections in these units. UNESP Univ Estadual Paulista, Inst Biosci, Dept Microbiol & Immunol, Bacteriol Lab, BR-18618970 Botucatu, SP, Brazil UNESP Univ Estadual Paulista, Inst Biosci, Dept Microbiol & Immunol, Bacteriol Lab, BR-18618970 Botucatu, SP, Brazil FAPESP: 05/02830-4

Made available in DSpace on 2015-02-02T12:39:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-11-01Bitstream added on 2015-02-02T13:07:48Z : No. of bitstreams: 1 S0074-02762014000700871.pdf: 385468 bytes, checksum: f0fb8c2d4a0176d73f34a9a41dce1605 (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study aimed to correlate the presence of ica genes, biofilm formation and antimicrobial resistance in 107 strains of Staphylococcus epidermidis isolated from blood cultures. The isolates were analysed to determine their methicillin resistance, staphylococcal cassette chromosome mec (SCCmec) type, ica genes and biofilm formation and the vancomycin minimum inhibitory concentration (MIC) was measured for isolates and subpopulations growing on vancomycin screen agar. The mecA gene was detected in 81.3% of the S. epidermidis isolated and 48.2% carried SCCmec type III. The complete icaADBC operon was observed in 38.3% of the isolates; of these, 58.5% produced a biofilm. Furthermore, 47.7% of the isolates grew on vancomycin screen agar, with an increase in the MIC in 75.9% of the isolates. Determination of the MIC of subpopulations revealed that 64.7% had an MIC ≥ 4 μg mL-1, including 15.7% with an MIC of 8 μg mL-1 and 2% with an MIC of 16 μg mL-1. The presence of the icaADBC operon, biofilm production and reduced susceptibility to vancomycin were associated with methicillin resistance. This study reveals a high level of methicillin resistance, biofilm formation and reduced susceptibility to vancomycin in subpopulations of S. epidermidis. These findings may explain the selection of multidrug-resistant isolates in hospital settings and the consequent failure of antimicrobial treatment. Universidade Estadual Paulista Instituto de Biociências de Botucatu Departamento de Microbiologia e Imunologia Universidade Estadual Paulista Instituto de Biociências de Botucatu Departamento de Microbiologia e Imunologia

Coagulase-negative staphylococci (CNS) are the microorganisms most frequently isolated from clinical materials and represent the leading cause of bacteremia in hospitals. The pathogenesis of infections caused by these bacteria can be aggravated due to antimicrobial resistance and virulence factors. Thus, the present study characterized the CNS species isolated from blood cultures from inpatients of the University Hospital of Botucatu School of Medicine for the detection of methicillin-resistant Staphylococcus (MRS) and staphylococcal enterotoxin genes. The gene mecA was detected in 83.7% CNS and the staphylococcal cassette chromosome mec was typed in MRS, indicating 45.8% type III, 25% type I, 11.1% type IV and 5.5% type II. The search for staphylococcal enterotoxin genes indicated that 77 samples were positive for at least one gene. The data obtained in this study highlight the importance of detecting and characterizing MRS and virulence factors to better understand the profile of the isolated CNS in order to appropriately treat infections caused by these microorganisms.

Staphylococcus spp. are frequently found in hospital environments and are associated with a wide variety of infections. Various virulence factors are responsible for the pathogenicity of staphylococci, among which staphylococcal enterotoxins and TSST-1 (toxic-shock syndrome) are noteworthy. In this study, 90 samples of Staphylococcus aureus and 90 samples of coagulase-negative staphylococci (CNS) isolated from different clinical materials were investigated by polymerase chain reaction (PCR) in order to study the genes encoding staphylococcal toxins A (sea), B (seb), C (sec-1), D (sed) and TSST-1(tst). The samples shown to be positive for the presence of one or more genes were tested for their capacity to express mRNA encoding the respective toxins by reverse transcription-PCR (RT-PCR). As regards the CNS species, S. epidermidis was the most frequently isolated, corresponding to 71.1% of the total number of samples of CNS investigated. One hundred and eight samples were positive according to PCR, of which 59 (54.6%) were S. aureus and 49 (45.4%) were CNS. S. aureus showed toxigenic genes for all classes of toxins investigated whereas CNS showed all genes except for that of toxin D. Assessment of mRNA expression by RT-PCR showed 43 positive samples, 37 (86.0%) S. aureus samples producing SEA, SEB, SEC, SED and/or TSST-1 and six (14.0%) CNS samples producing SEA and SEC. RT-PCR and sequencing of PCR products confirmed the toxigenic capacity of S. epidermidis and S. lugdunensis, indicating the need for greater attention to such microorganisms when they are isolated from infectious processes.

Oxacillin is the main drug used for the treatment of Staphylococcus aureus infections. However, resistance of S. aureus to oxacillin has become a major problem over recent decades. The aim of this study was to determine oxacillin resistance in S. aureus isolates obtained from the University Hospital of the Botucatu Medical School, Universidade Estadual Paulista, Brazil.A total of 102 isolates collected between 2002 and 2006 were analyzed by detection of the mecA gene, cefoxitin and oxacillin disk diffusion methods, screening test on Mueller-Hinton agar and E-test.Forty-six (45.1%) isolates were mecA positive. The oxacillin disk diffusion method showed 86.9% sensitivity and 91.1% specificity. The screening method and cefoxitin disk diffusion presented a similar sensitivity (91.3%) and the same specificity. The E-test showed 97.8% sensitivity and the same specificity as observed for the other methods.The E-test yielded the best results compared to the other methods.