Antibiotic Resistant Genes in Some Pathogenic Bacteria and Its Correlation with Safety of Milk and Dairy Products

A total of 270 samples of raw milk and dairy products were investigated for the presence of ESBL E. coli and S. aureus (MRSA). Data revealed that 41(15.6%) and 45(16.8%) were total positive samples for E. coli and S. aureus, respectively. The examined samples of raw milk (n=100; 33% and 30%), white soft cheese (n=100; 2% and 0%), ras cheese (n=50; 12% and 30%) and ice cream (n=20; 0% and 0%) were positive for E. coli and S. aureus, respectively. The identified serotypes of E. coli involved O128: H2 (26.8%), O91: H21 (19.5%), O78 (9.75%), O26: H11 (17.1%), O119: H6 (12.2%), O121: H7 (4.9%), O153: H2 (4.9%), O17: H18 (2.4%), and O159 (2.4%). The averages of MDR index were 0.424 and 0.493 for E. coli and S. aureus, respectively. Molecular characterization of isolates with a MAR index ≥ 0. 2 revealed that blaTEM, blaCTX-M, blaSHV, and blaOXA genes in 100%, 100%, 57.1%, and 71.4% in E. coli isolates and blaZ, optrA, vanA, and mecA genes were detected in 85.7%, 28.6%, 42.9%, and 85.7% in S. aureus isolates, respectively. The effectiveness of neutral electrolyzed water (NEW) on the viability of ESBL E. coli and MRSA isolates was assessed in relation to time (5, 10, and 15 minutes), a significant reduction in counts compared to control samples at 15 minutes of exposure. The count of ESBL E. coli and MRSA decreased to 81.3±1.04 and, 1.4x102±1.05 cfu/cm2 compared to control samples that were 1.9x106±1.12 and 5.2x106±1.3 cfu/cm2, respectively. NEW showed broad-spectrum bactericidal activity.