RESUMO
AIM: To evaluate the influence of aeration on persister levels from Acinetobacter calcoaceticus-baumannii isolates exposed to meropenem or tobramycin, as well as analyze morphological and structural changes in persisters. MATERIALS & METHODS: Levels of persisters were determined after a 48-h exposure to tobramycin or meropenem under aerated or static conditions, and persisters were analyzed by scanning and transmission electron microscopy. RESULTS: The fractions of persisters varied between isolates. Aeration reduced cell survival under each antibiotic treatment, and cell survival decreased as the tobramycin concentration was increased. Interestingly, division septa were observed in persisters by electron microscopy. CONCLUSION: Aeration may have stimulated bacterial growth, providing more targets for antibiotic action and leading to increased production of reactive oxygen species, which decreased levels of persisters.
Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/fisiologia , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Oxigênio/farmacologia , Acinetobacter baumannii/ultraestrutura , Humanos , Meropeném , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Tienamicinas/farmacologia , Tobramicina/farmacologiaRESUMO
In the present study, we report the effect of several acaricides on the enzyme activity of a Boophilus microplus recombinant glutathione S-transferase (rGST). GST was expressed in Escherichia coli and was purified with glutathione (GSH) affinity column chromatography. The kinetic constants were determined by reacting GST with the substrates 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione. We report the effect of several acaricides on the enzyme activity of rGST. Some acaricides (ethion, amitraz, chlorpyrifos, DDT, cypermethrin, diazinon, ivermectin, deltamethrin and flumethrin) inhibited rGST. Contrarily, coumaphos had an activating effect. Although the accurate mechanisms of the B. microplus resistance to acaricides remain elusive, this work helps in understanding how acaricides can interact with GST.