Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus(MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.

Currently, hospital infection is a serious public health problem, and several factors may influence the occurrence of these infections, including the presence of insects, which are carriers of multidrug-resistant bacterial species. The aim of this study was to isolate staphylococci carried by insects in two public hospitals of Vitoria da Conquista, Bahia and to identify the resistance profile, pathogenicity and efficacy of disinfection of the premises. A total of 91 insects were collected in 21 strategic points of these hospitals, and 32 isolated strains of Staphylococcus aureus were isolated. Based on antibiogram and Minimum Inhibitory Concentration results, 95% of these strains were susceptible to oxacillin. These strains were also evaluated for the presence of resistance genes encoding resistance to oxacillin/methicillin by polymerase chain reaction, but the sample was negative for this gene. Pathogenicity tests were performed in vitro biofilm formation induced by glucose, where it was found that eight (27.58%) strains were classified as biofilm producers and 21 (72.4%) as stronger producers. In addition, we performed PCR for their virulence genes: Sea (enterotoxin A), SEB (B), Sec (C), PVL (Panton-Valentine Leukocidin), ClfA (clumping factor A) and Spa (protein A). Of these, Sea, Spa PVL were positive in 7 (21.8%), 2 (6.3%) and 1 (3.1%) samples, respectively. The analysis of cytokine induction in the inflammatory response of J774 macrophages by isolates from the two hospitals did not show statistical difference at the levels of IL-6, TNF-α, IL-1 and IL-10 production. In addition, we verified the antimicrobial activity of disinfecting agents on these strains, quaternary ammonium, 0.5% sodium hypochlorite, 1% sodium hypochlorite, 2% sodium hypochlorite, 2% glutaraldehyde, Lysoform(®), 70% alcohol solution of chlorhexidine digluconate, 2% peracetic acid, and 100% vinegar. Resistance was seen in only for the following two disinfectants: 70% alcohol in 31 (96.8%) samples tested and vinegar in 30 (93.8%) samples. The study demonstrated the presence of resistant and pathogenic organisms conveyed by insects, thus suggesting improvement in efforts to control these vectors.

This study investigates the biofilm formation, presence and distribution of virulence genes and the capacity to induce an inflammatory response in strains of Staphylococcus aureus isolated from milk samples in Bahia, Brazil. A total of 132 samples of raw milk were collected from four dairy farms (designated A to D) located in southwestern Bahia, in the municipality of Vitória da Conquista, from October/2009 to September/2010. After processing of the samples, 94 (71.2%) S. aureus isolates were obtained. These strains were subjected to the antibiogram method MIC (Minimum Inhibitory Concentration). As for the pathogenicity, tests were performed in vitro biofilm formation induced by glucose. Moreover, we performed PCR for their virulence genes: sea (enterotoxin A), seb (B), sec (C), pvl (Panton-Valentine Leukocidin), clfA (Clumping Factor A) and spa (protein A) and analysis of cytokine induction in the inflammatory response of J774 macrophages by exocellular lipoteichoic acid. No isolates were resistant to oxacillin and vancomycin. In biofilm production, 5.31% (5/94) isolates did not produce biofilm, 5.31% (5/94) of the samples were poor producers, 15.96% (15/94) strains were moderate producers, 18.09% (17/94) were producers and 55.32% (55/94) of isolates were strong biofilm producers. One (1.06%) isolate expressed the seb gene, one (1.06%) sec, 18 (19.2%) cflA and 44 (46.8%) had spa. There was no expression of sea and pvl between isolates analyzed. The analysis of cytokine induction in the inflammatory response did not show statistical difference in the levels of IL-6, TNF-α and IL-10 induction. However, there was statistical difference in IL-1 induction between isolates from different farms. Thus, it