PHÁT HIỆN VÀ PHÂN TÍCH ĐỊNH LƯỢNG TRỰC KHUẨN GRAM ÂM KHÁNG COLISTIN TRONG MẪU THỊT GÀ, THỊT LỢN BÁN LẺ TẠI THÁI BÌNH

Abstract

The study was conducted to detect and quantify colistin-resistant Gram-negative bacteria in retail chicken and pork at Nguyen Xa, Vu Thu, Thai Binh. After homogenization, chicken and pork samples were diluted in peptone buffer water (BPW) and cultured on Chromagar ECC (ECC) and Chromagar COL-APSE (COL-APSE) medium at 37^oC for 18-24 hours. Bacteria grown on the agar were classified based on colony’s color according to instruction of the manufactory and the density of bacteria in each sample was determined. For each meat sample, 1 - 3 representative colonies grown on COL-APSE medium were isolated for determining the minimum inhibitory concentration (MIC) to colistin according to CLSI guidelines. The prevalence of colistin-resistant Gram-negative bacteria contaminated in retail meat samples was relatively high, with 86.7% in chicken and 73.3% in pork. The concentration of colistin-resistant Gram-negative bacteria in meat samples averaged 10³ to 10⁶ CFU/g. E. coli, Acinetobacter and coliform were common bacteria contaminated in retail meat samples. Among the Gram-negative strains, 77.4% of the strains were colistin-resistant (MIC ≥ 4mg/L). The results showed that among the E. coli and coliform bacteria contaminated in meat samples, colistin-resistant bacteria accounted for only a low percentage of less than 10%. The contamination of colistin-resistant Gram-negative bacteria in retail chicken and pork was quite common in Thai Binh, so it is necessary that appropriate food hygiene and safety measures be taken to prevent the spread of colistin resistant bacteria in the community.