ABSTRACT
O presente trabalho tem como objetivo estudar o comportamento e a resistência de bactérias em relação a agentes químicos com ação antimicrobiana em diferentes concentrações e determinar a quantidade mínina para que ocorra a inibição dos microrganismos. Serratia marcescens, Proteus mirabilis, Pseudomonas aeruginosas, Escherichia coli, Bacillus cereus e Staphylococcus aureus, foram os microrganismos utilizados, os quais foram semeados em meio Plate Count Agar (PCA). Na sequência, aplicaram-se os testes com os agentes controladores, nas concentrações de 0,5 %, 1,5%, 3,0%, 5,0%, 7,0% e 10,0 %, e os álcoois pré-determinados. A identificação da eficácia foi definida atraves frequência e índice de inibição. Foram realizadas análises de 13 substâncias nas seis diferentes concentrações, ou seja, 468 amostras totalizadas no experimento. Com relação aos microrganismos estudados observou-se, dentre os componentes escolhidos, uma ampla resistência, mesmo em concentrações maiores. O estudo demonstrou variação de resistência e sensibilidade, sendo ácido ascórbico o agente com a maior concentração inibitória mínima e as menores concentrações foram do peróxido de hidrogênio. Considerando importância do uso desses compostos na inibição e no controle de agentes bacterianos em diferentes áreas, torna-se vital o conhecimento da amplitude de seu espectro, assim, alguns produtos, nas diluições recomendadas para uso, revelaram possuir atividade antibacteriana mais reduzida ou inexistente.
The present work aims at studying the behavior and bacteria resistance against chemical agents with antimicrobial action in different concentrations and determining the minimum quantity for micro-organism inhibition. This study used Serratia marcescens, Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus and Staphylococcus aureus micro-organisms, which were seeded in Plate Count Agar (PCA) medium. After, the tests were applied with controlling agents, at concentrations of 0.5%, 1.5%, 3.0%, 5.0%, 7.0% and 10.0%, and predetermined alcohols. Effectiveness was identified by frequency and inhibition index. Analyses were carried out on 13 substances in six different concentrations, i.e., a total of 468 samples in the experiment. In relation to the studied micro-organism, a broad resistance could be observed among the chosen components, even in larger concentrations. The study presented resistance and sensitivity variation, with ascorbic acid being the agent with the greatest minimum inhibitory concentration, while hydrogen peroxide presented the lowest concentrations. Considering the importance of these compounds in inhibiting and controlling bacterial agents in different areas, it is vital to expand the knowledge on the broadness of its spectrum, since some of the products, at the recommended use dilutions, presented low or non-existent antibacterial activity.
Subject(s)
Bacteria , Bacterial Growth , Chemical Compounds , Disease Resistance , Anti-Infective AgentsABSTRACT
The presence of Aeromonas ssp. in food has been demonstrated. They are often introduced from water, which is the natural habitat of many species and is thought to be the main source of contamination. The occurrence of Aeromonas ssp. was investigated in 70 water samples of a bovine abattoir. Aeromonas ssp. were present in 21.4(per cent) of water samples. A.hydrophila was isolated from 11.4(per cent) of supplying water samples and from 25.7(per cent) of the water drained from carcasses, whereas A. sobria was sole isolated from 5.7(per cent) of supplying water samples. Although greater number of positive samples were from water drained from carcasses, only A.hydrophila isolates were present. This suggests that the supplying water is the source of contamination. The antibiotic susceptibility testing revealed all strains were resistant to ß-lactam antibiotics. However, the susceptibility to other antimicrobials was variable, being A.hydrophila more resistant than A. sobria strains. The investigation for virulence factors revealed positive reactions of hemolysis and hemagglutination. The results indicate that Aeromonas ssp. are present in the supplying water system. These microorganisms may be a potential contaminant of carcasses and widespread in derived food.