| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1197-2 | ||||
Resumo:The antibiotic resistance has become one of the biggest complication in the treatment of bacterial diseases, which leads to a worse prognosis for patients and generates higher costs compared to susceptible microorganisms. Therefore, several studies have been carried out in search of new compounds that are capable of combating resistant bacteria. Thus, the objective of this work is to analyze the action of the essential oil of Lippia origanoides Kunth and its major compound thymol against clinical isolates of Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa resistant to carbapenems. The oil of L. origanoides Kunth was obtained by hydrodistillation in a clevenger-type apparatus and tested with the clinical isolates of A.baumannii (AB03), K. pneumoniae (KP1), P. aeruginosa (PA4). For the analysis of antimicrobial activity, the minimum inhibitory concentration (MIC) was quantified by the broth microdilution method according to CLSI (M100-S26). Then, the minimum bactericidal concentration (MBC) was determined, where the subculture was performed using 100 µl of the wells that did not have visual growth and cultivated in BHI agar plates. The plates were incubated at 37 ºC for 24h and the MBC was the lowest concentration of the subculture in which there was no growth of colonies on the plates. The oil and thymol were diluted in DMSO 0.5% and tested at range concentrations of 4.9 to 2,500 µg/mL. MIC was determined for two carbapenems (meropenem and imipenem) at concentrations of 2 to 1,024 µg/mL. The three strains showed resistance to both carbapenems tested, with MIC of 128 µg/mL for both antibiotics against AB03, MIC of 16 and 128 µg/mL against KP1 for meropenem and imipenem, respectively, and MIC of 16 and 128 µg/mL for meropenem and imipenem against PA4, respectively. The essential oil of L. origanoides Kunth presented MIC of 312, 1,250 and 625 µg/mL for AB03, KP1 and PA4, respectively. While thymol showed MICs of 156 µg/mL for AB03 and 625 µg/mL for KP1 and PA4. Both compounds therefore adopted similar MICs for resistant isolates. The chemical analysis of the oil used in this study showed that thymol corresponds to 80% of the oil's composition. The similarity of the activity of both compounds demonstrates that, against the isolates tested here, thymol was probably responsible for the activity of the oil. Only against the AB03 strain did there be a reduction in the MIC of the oil in relation to thymol, halving the MIC value.A. baumannii, P.aeruginosa and enterobacteriaceae such as K. pneumoniae are on the critical priority list for resistant microorganisms in the WHO guidelines, which increases the importance of the activity of the compounds reported here. This result expands the possibility of studying oils and their compounds for the discovery of new antimicrobial drugs. Palavras-chave: antibiotic, antimicrobial activity, microdilution, resistance Agência de fomento:Cearense Foundation for Scientific and Technological Development (FUNCAP) | |||||