Characterization of Multidrug-Resistant Staphylococcus aureus Isolates and Comparison of Methods of Susceptibility to Vancomycin.

S. aureus are among the main bacteria causing problems related to multidrug resistance in nosocomial infections. Therefore, it is necessary to carry out a reliable and rapid diagnosis for the identification of the bacteria and characterization of its susceptibility profile, especially vancomycin, which is an alternative treatment against multidrug-resistant (MDR) S. aureus. Thus, the goal of this study was to characterize isolates of S. aureus regarding the resistance and virulence and to check the susceptibility to vancomycin, through different methods, for comparative purposes. Seventeen antimicrobials were tested to assess the susceptibility profile. It was evaluated the presence of identification (nuc), resistance (mecA and blaZ), biofilm (icaA and icaD) and siderophore (sfaD and sbnD) genes. The susceptibility to vancomycin was evaluated by Minimum Inhibitory Concentration (MIC) by broth microdilution (BMD), E-test, commercial panel (Kit), and Phoenix equipment. Most S. aureus (93,33%) was classified as MDR. These isolates were 100% positive for nuc, mecA, icaA, icaD, and sfaD genes; 96.67% for sbnD and 33.33% for blaZ. In relation to BMD, all methods correctly classified the susceptibility of the isolates; however, regarding the exact MIC value for vancomycin, Phoenix showed agreement of 63.33%, E-test (33.33%) and Kit (26.66%). In conclusion, most of S. aureus was considered MDR. Also, they presented resistance, biofilm production, and siderophores genes, showing the pathogenic potential of these bacteria. Besides, the Phoenix test was considered the most effective, as it presents advantages, such as identification of the microorganism and a greater number of antimicrobials tested at a time.

Influência do polipirrol e dos níveis de salinidade na formação de biofilme em Aeromonas spp / Influence of polypyrrole and salinity levels on biofilm formation in Aeromonas spp

Bactérias do gênero Aeromonas são patógenos altamente disseminados no ambiente aquático, responsáveis por grandes perdas econômicas na piscicultura de diversos países. São micro-organismos oportunistas e sua patogenicidade está ligada a alguns fatores de virulência, como a formação de biofilme. O estresse salino é um dos fatores que favorecem a formação dessas colônias e, consequentemente, o aumento de infecções. Essas infecções quando estão associadas ao biofilme são ainda mais resistentes aos antimicrobianos. Nesse contexto, o polipirrol destaca-se como uma alternativa antimicrobiana por possuir vários atributos terapêuticos e não apresentar toxicidade aos organismos. Dessa forma, o objetivo desse estudo foi avaliar o perfil de susceptibilidade e a capacidade de formação de biofilme dos isolados de Aeromonas spp. associados aos diferentes níveis de salinidade e polipirrol. Determinou-se a atividade antibacteriana dos isolados e ensaios de motilidade foram realizados com bactérias que carreavam o gene fla. Também verificou-se a capacidade do cloreto de sódio e polipirrol em interferir na formação do biofilme. Os resultados foram evidenciados com a microscopia eletrônica de varredura. As concentrações de 2 e 3% de NaCl inibiram a motilidade bacteriana. Na formação do biofilme, 83% dos isolados bacterianos induziram a produção na concentração de 0,25%. O polipirrol causou a morte de todos os isolados testados na concentração de 125μg/mL. Além disso, esse composto diminuiu a motilidade bacteriana nas concentrações de 0,25 a 3%, sendo que em relação à produção de biofilme, não houve interferência. Esses resultados evidenciam que os diferentes níveis de NaCl influenciam na formação do biofilme favorecendo a persistência da infecção. Este estudo também realçou a potencialidade do polipirrol como agente bactericida, sendo uma alternativa eficaz às drogas antimicrobianas para o tratamento das infecções causadas por Aeromonas spp.(AU)

Bacteria of the genus Aeromonas are highly disseminated pathogens in the aquatic environment, responsible for great economic losses in the pisciculture of several countries. They are opportunistic microorganisms and their pathogenicity is linked to some virulence factors, such as biofilm formation. Saline stress is one of the factors that favor the formation of these colonies and, consequently, the increase of infections. These infections, when associated with biofilm, are even more resistant to antimicrobials. In this context, polypyrrole stands out as an antimicrobial alternative because it has several therapeutic attributes and does not present toxicity to organisms. Thus, the objective of this study was to evaluate the susceptibility profile and the biofilm formation capacity of Aeromonas spp. associated with different levels of salinity and polypyrrole. The antibacterial activity of the isolates was determined and motility assays were performed with bacteria bearing the fla gene. The ability of sodium chloride and polypyrrole to interfere with biofilm formation has also been demonstrated. The results were evidenced with scanning electron microscopy. Concentrations of 2 and 3% of NaCl inhibited bacterial motility. In the biofilm formation, 83% of the bacterial isolates induced production at the concentration of 0.25%. Polypyrrole caused the death of all the isolates tested at the concentration of 125μg/mL. In addition, this compound decreased bacterial motility at concentrations of 0.25 to 3%, and no biofilm was produced. These results show that the different levels of NaCl influence in the formation of the biofilm favoring the persistence of the infection. This study also highlighted the potential of polypyrrole as a bactericidal agent, being an effective alternative to antimicrobial drugs for the treatment of infections caused by Aeromonas spp.(AU)

Antibacterial behavior of polypyrrole: The influence of morphology and additives incorporation.

The antibacterial behavior of polypyrrole (PPy) depends on a diversity of structural parameters such as surface area, aggregation level and additives (metal nanoparticles) incorporation. This paper summarizes the influence of different preparation procedures of PPy on action of resulting antibacterial composite against Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. The bactericidal action has been assigned to morphology (size of polypyrrole nanoparticles). The electrostatic interaction established between polymer nanoparticles and bacteria provokes the bacterial cell death and returns advantages in comparison with conventional composites of polypyrrole decorated with metal nanoparticles.