Bactericidal antibiotic-phytochemical combinations against methicillin resistant Staphylococcus aureus

Methicillin resistant Staphylococcus aureus (MRSA) infection is a global concern nowadays. Due to its multi-drug resistant nature, treatment with conventional antibiotics does not assure desired clinical outcomes. Therefore, there is a need to find new compounds and/or alternative methods to get arsenal against the pathogen. Combination therapies using conventional antibiotics and phytochemicals fulfill both requirements. In this study, the efficacy of different phytochemicals in combination with selected antibiotics was tested against 12 strains of S. aureus (ATCC MRSA 43300, ATCC methicillin sensitive S. aureus or MSSA 29213 and 10 MRSA clinical strains collected from National University Hospital, Singapore). Out of the six phytochemicals used, tannic acid was synergistic with fusidic acid, minocycline, cefotaxime and rifampicin against most of strains tested and additive with ofloxacin and vancomycin. Quercetin showed synergism with minocycline, fusidic acid and rifampicin against most of the strains. Gallic acid ethyl ester showed additivity against all strains in combination with all antibiotics under investigation except with vancomycin where it showed indifference effect. Eugenol, menthone and caffeic acid showed indifference results against all strains in combination with all antibiotics. Interestingly, no antagonism was observed within these interactions. Based on the fractional inhibitory concentration indices, synergistic pairs were further examined by time-kill assays to confirm the accuracy and killing rate of the combinations over time. The two methods concurred with each other with 92% accuracy and the combinatory pairs were effective throughout the 24 hours of assay. The study suggests a possible incorporation of effective phytochemicals in combination therapies for MRSA infections.

Occurrence of methicillin resistant Staphylococcus aureus (MRSA) among clinical samples in tehran-iran and its correlation with polymorphism of specific accessory gene regulator (AGR) groups

Methicillin-Resistant Staphylococcus aureus (MRSA) is responsible for an increasing number of serious hospital and community acquired infections. Virulence gene expression in Staphylococcus aureus is orchestrated by regulators such as the accessory gene regulator (agr). Staphylococcal strains are divided into four major agr groups (agrI-IV) on the basis of agrD and agrC polymorphisms. The purpose of this study was to define the prevalence of MRSA strains in appointed Tehran's hospitals and then to define and compare the proportion of agr I, II, III, IV polymorphisms between MRSA and Methicillin Sensitive Staphylococcus aureus (MSSA) strains. A total of 235 isolates were evaluated by conventional antibiotic susceptibility tests and PCR for agr and mecA genes. 112 strains were MRSA (47.5%) and the most prevalent agr specific group was agr I followed by agr III, agr II and agr IV, respectively. The prevalence of agr groups amongst MRSA and MSSA strains was not statistically significant (P>0.05). This study suggests that agr I is not only the most prevalent agr type in MRSAs but also the most common one in Methicillin Sensitive Staphylococcus aureus (MSSA) strains in Iran.

Evaluation of the in vitro antimicrobial activity of an ethanol extract of Brazilian classified propolis on strains of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is one of the most frequent causes of hospital acquired infections. With the increase in multiple drug resistant strains, natural products such as propolis are a stratagem for new product discovery. The aims of this study were: to determine the in vitro antimicrobial activity of an ethanol extract of propolis; to define the MIC50 and MIC90 (Minimal Inhibitory Concentration - MIC) against 210 strains of S. aureus; to characterize a crude sample of propolis and the respective ethanol extract as to the presence of predetermined chemical markers. The agar dilution method was used to define the MIC and the high performance liquid chromatography (HPLC) method was used to characterize the samples of propolis. MIC results ranged from 710 to 2,850 µg/mL. The MIC50 and MIC90 for the 210 strains as well as the individual analysis of American Type Culture Collection (ATCC) strains of Methicillin-susceptible Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA) were both 1,420 µg/mL. Based on the chromatographic analysis of the crude sample and ethanol extracted propolis, it was concluded that propolis was a mixture of the BRP (SP/MG) and BRP (PR) types. The results obtained confirm an antimicrobial activity in relation to the strains of the S. aureus tested.

Detecção de Staphylococcus aureus e Staphylococcus aureus resistentes à meticilina em profissionais da saúde lotados no Instituto Lauro de Souza Lima, Bauru-SP / Detection of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in health care workers packed the Instituto Lauro de Souza Lima, Bauru-SP

O Staphylococcus aureus (S. aureus) é um patógeno comumente isolado de amostras biológicas humanas. É encontrado com freqüência na pele e fossas nasais de indivíduos saudáveis, podendo provocar desde simples infecções ate graves enfermidades. Cerca de 40% da população adulta saudável é portadora nasal de S. aureus e esta taxa pode ser ainda maior em ambientes hospitalares, especialmente entre os pacientes internados e equipe médica. O surgimento da resistência à meticilina, uma penicilina sintética, pelo S. aureus e sua disseminação tornaram as medidas de controle epidemiológico ainda mais importantes no que diz respeito à prevenção de infecções hospitalares e, mais recentemente, comunitárias. Profissionais da área de saúde que são portadores nasais de S. aureus e Staphylococcus aureus resistentes a meticilina (MRSA) são considerados importantes fontes de disseminação do patógeno e estão intimamente envolvidos na epidemiologia dos mesmos. Investigação constante e adoção de medidas de controle na admissão dos pacientes em áreas de alta endemicidade para MRSA, tais com CTIs e centros de dermatologia, são consideradas estratégias efetivas em termos de custo-benefício contra as ionfecções hospitalares, bem como o estudo da prevalência de MRSA em profissionais de saúde que atuam nos referidos lugares. O objetivo do estudo foi verificar a colonização por S. aureus e MRSA nas fossas nasais de profissionais das equipes médicas de enfermagem e dos laborat´rios em um hospital de dermatologia de nível terciário - Instituto Lauro de Souza Lima - Bauru/SP...