Dados do Trabalho

Título

Antibacterial activity of quercetin and ceftazidime against Klebsiella pneumoniae strains

Introdução

Over the years, the increase in resistance to cephaloporins in hospital strains of Klebsiella pneumoniae has consolidated the development of severe co-infections, the chronicity of these infections and the increase in morbidity and mortality in patients. In this sense, promising molecules with the potential to inhibit resistance are being sought, in particular quercetin (QUER), a flavonoid with diverse biological properties. In this sense, combining QUER with cephalosporins is a promising therapeutic strategy. 

Objetivo (s)

Thus, this study aimed to evaluate the antibacterial activity of QUER associated with ceftazidime (CAZ) against cephalosporin-resistant K. pneumoniae. 

Material e Métodos

The determination of the minimum inhibitory concentration (MIC) of QUER and CAZ against K 25 A2, K 26 A2, K 29 A2, K 31 A2 and K 32 A2 strains was performed by the broth microdilution method according to the Clinical and Laboratory Standards Institute. After determining the MIC, the interaction between QUER and CAZ was carried out using the Checkerboard assay, and the Fractional Inhibitory Concentration Index (FICI) was calculated according to the following equation ∑FICI = FICIa + FICIb = (Ca / MICa) + (Cb / MICb). 

Resultados e Conclusão

The MIC of QUER and CAZ were 250 µg/mL and 500 µg/mL, 2000 µg/mL and 62.5 µg/mL, 1000 µg/mL and 62.5 µg/mL, 2000 µg/mL and 31.25 µg/mL and 500 µg/mL and 31.25 µg/mL for K 25 A2, K 26 A2, K 29 A2, K 31 A2 and K 32 A2, respectively. The of FICI from the combination of QUER and CAZ was de 0.3, 0.2, 0.4, 0.2 and 0.3 for K 25 A2, K 26 A2, K 29 A2, K 31 A2 and K 32 A2, respectively, indicating synergistic interactions. After the interaction test the MIC of QUER+CAZ were 31.2/1.95 µg/mL, 15.6/1.95 µg/mL, 31.2/3.9 µg/mL, 15.6/1.95 µg/mL and 15.6/1.95 µg/mL for K 25 A2, K 26 A2, K 29 A2, K 31 A2 and K 32 A2, respectively. Thus, QUER associated with CAZ potentiated the antibacterial activity, promoting the sensitisation of bacterial strains to ceftazidime, presenting itself as a potential inhibitor of bacterial resistance and an alternative for the treatment of bacterial resistance. of infections caused by K. pneumoniae strains.

Palavras Chave

bacterial resistance; combination therapy; Gram-negative bacteria; natural products.