Prevalence and antibiotic resistance of Staphylococcus aureus in raw milk produced in Northern Jordan

Abstract

This study aimed to assess contamination of raw milk with Staphylococcus aureus and to measure Minimum Inhibitory Concentration (MIC) of antibiotics. Furthermore, it examined effect of region, month, and milk source on Bacterial Growth Rate (BGR) and Multidrug Resistance (MDR). Results show that sample distribution is affected by month, region, and milk source. E.g., the highest infection rate was recorded in March, with majority of samples concentrated in Qasabat Irbid. Furthermore, cow's milk dominated the samples, with majority of S. aureus growing. Meanwhile, distribution of MDR was not significant. Furthermore, region has a significant effect on BGR and MDR. The interaction of region and response reveals that effect of region differed depending on presence of MDR. Regarding laboratory results, MIC against S. aureus ranges from 1.00 for the most effective Azithromycin to 4.00 µg/mL for the least effective Fosfomycin. Furthermore, there are significant differences in the WHO classifications. Accordingly, antibiotics are ranked according to their importance and priority of use. CXM-AMC may top list as the most widely used and effective first-line drug. OT, DOX, and SXT follow, which are highly important. AMP and CEP are followed by GN, ENR, CIP, FFC, and FUR, with moderate importance. Finally, CEN, AZM, SPI, TY, N, CS, and FOS are of limited use in resistant cases. Therefore, the study recommends focusing on monitoring isolates of S. aureus. Antibiotics should be selected based on their MIC values. Therefore, priority should be given to using highly effective antibiotics as first-line, with less-needed reserved for resistant cases.