Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) have increasingly been reported in healthy communities. This study aimed to assess the rate of S. aureus in general and MRSA in particular from nasal secretion of children in daycare centers in Vitória da Conquista, Brazil. The isolates were identified based on morphology, biochemical tests and by PCR. Detection of virulence genes, biofilm production, and susceptibility test by disk diffusion agar were performed. MRSA isolates were characterized by spa, SCCmec, and multilocus sequence typing (MLST). S. aureus were recovered from 70 (47.3%) of 148 children. Among the 11 MRSA strains (15.7%), two SCCmec types (IV and V) were detected. MLST identified four STs related to three clonal complexes (CC): 5, 45, and 398. Four spa types were found circulating in this setting. Resistance of S. aureus isolates to ampicillin, erythromycin, ciprofloxacin, clindamycin, and tetracycline was 80%, 32.8%, 7.1%, 7.1% and 4.3%, respectively. One isolate presented intermediate resistance to vancomycin detected by Etest methodology. All strains were biofilm producers. The virulence genes seb, sec, spa, and pvl were detected in some isolates. This study revealed a high rate of children carrying MRSA among healthy attendees in daycare centers in Vitória da Conquista, Brazil.

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Human milk is the best nutrient for infants. The donor human milk is stored in a milk bank before pasteurization. However, the human milk is not sterile and could be colonized with different types of bacteria. Many studies have shown S. aureus to be the most prevalent potential pathogen detected in human milk. This study characterized 22 methicillin-resistant and methicillinsensitive Staphylococcus aureus isolates from raw human milk for the presence of virulence genes and agr type. Moreover, the genotypic as identified characterization was realized. The presence of virulence genes sei, seg, sec, seh, and etb was identified in resistant and sensitive strains. We observed the predominance of agr type II. The presence of SCCmec IV (67%, 4/6) and V (33%, 2/6) characterized resistant strains as CA-MRSA. Endemic lineages detected (ST1635/CC5-t002, ST5/CC5-t002, ST72/CC5-t126, ST1/CC1-t127, ST45/CC45-t065, and ST398/t1451) could be related to epidemic clones, such as USA800/ ST5, USA700/ST72, USA400/ST1, USA600/ST45, and ST398. This study made it possible to understand the characteristics of virulence and clonality of some strains that circulate in breast milk in our region. The discovery of human milk colonization by MSSA and MRSA strains with molecular characteristics similar to infectious clones spread globally demonstrates the importance of monitoring strains that can spread and cause serious infections.

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for high morbidity and mortality rates. Citral has been studied in the pharmaceutical industry and has shown antimicrobial activity. This study aimed to analyze the antimicrobial activity of citral in inhibiting biofilm formation and modulating virulence genes, with the ultimate goal of finding a strategy for treating infections caused by MRSA strains. Citral showed antimicrobial activity against MRSA isolates with minimum inhibitory concentration (MIC) values between 5 mg/mL (0.5%) and 40 mg/mL (4%), and minimum bactericidal concentration (MBC) values between 10 mg/mL (1%) and 40 mg/mL (4%). The sub-inhibitory dose was 2.5 mg/mL (0.25%). Citral, in an antibiogram, modulated synergistically, antagonistically, or indifferent to the different antibiotics tested. Prior to evaluating the antibiofilm effects of citral, we classified the bacteria according to their biofilm production capacity. Citral showed greater efficacy in the initial stage, and there was a significant reduction in biofilm formation compared to the mature biofilm. qPCR was used to assess the modulation of virulence factor genes, and icaA underexpression was observed in isolates 20 and 48. For icaD, seg, and sei, an increase was observed in the expression of ATCC 33,591. No significant differences were found for eta and etb. Citral could be used as a supplement to conventional antibiotics for MRSA infections.

Summary Background Staphylococcus aureus is a human pathogen of clinical importance related to a variety of infections. Aim The objective of this study was to analyze the molecular and epidemiological characteristics of S. aureus obtained from healthcare professionals (HCP) of a hospital in southwestern Bahia, Brazil. Methods Samples were collected from hands, nasal cavity, and laboratory coats of 80 HCP. The bacterial isolates recovered from 240 samples were identified as S. aureus, and then analyzed for their antimicrobial resistance profile, genotypic characterization, and pathogenicity. Findings 178 isolates were identified as S. aureus , being mostly isolated from the nasal cavity. Thirty isolates (16.8%) were characterized as MRSA. The virulence gene frequency varied according to isolate source. All virulence genes were identified in at least one hand isolate. Isolates from laboratory coats did not show seb and pvl. Isolates from the nasal cavity did not exhibit pvl. The SCCmec type I was identified in 56.7% of MRSA isolates. Among MRSA isolates, 14 PFGE pulsotypes were characterized, with profile A being predominant (nine isolates). Clonal complexes CC5, CC45, and CC398 were found. MRSA isolates induced cytokine gene expression in macrophages, with IL-10 and IL-17 being expressed more often. Conclusion We found a high colonization rate for S. aureus among HCP. Moreover, we observed that MRSA strains presented different virulence factors and could induce cytokine gene expression, indicating an urgent need to control colonization rates of HCP by MRSA isolates in order to protect hospital patients and the general public.

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Significance and impact of the study: Our data suggest that Lactobacillus plantarum Lp62 could be used as a potential treatment against genital infections, especially bacterial vaginosis caused by Gardnerella vaginalis. We hypothesize that this strain has significant therapeutic potential as it topically helps restore vaginal microbiota.