Comparison of Antibiotic Resistance Rates of Staphylococcus Aureus Isolates from Mastitic Milk between Years 2021 and 2022 in Abruzzo and Molise Regions, Italy

Le résumé fourni par la source

This study was aimed to highlight the trends of antibiotic resistance (AR) prevalence in two annualities, 2021 and 2022, for a major bacterial pathogen, Staphylococcus aureus, that causes mastitis infections necessitating antibiotic therapy in milk producing animals. Fiftyfour isolates, 27 for each year, were obtained from routine tests for the identification of clinical mastitis agents carried out in the author institution for four provinces of Abruzzo and Molise regions, Italy. These were analyzed for phenotypic resistance to eight antibiotics used in human therapy suggested for testing by the European guidelines and for the presence of 14 transferable AR genes by qPCR tests developed in this study. The prevalence of AR genes was lower than reported in studies carried out in other countries, except for blaZ detected in 59.2% 2021 isolates and in 48.1 % 2022 isolates. However, some iso-lates with blaZ were not resistant to cefoxitin. One methicillin resistant (MRSA) strain, carrying the mecA gene, was isolated in 2022 and two multidrug resistant (MDR) isolates were identified in 2021. Other AR genes occurring were aph3’-III (two 2021 isolates), ant6-Ia (one 2021 isolate), ermB (one 2022 isolate), ermC/T (two 2021 isolates) and mph (one 2022 isolate). An interview to the veterinarians who conferred the samples indicated a good management of antibiotic therapies in farms that could explain why AR prevalence was stable in the time inter-val considered, thus underlining the effectiveness of controlled antibiotic usage in containing the AR threat.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.