Prevalence and Antimicrobial Resistance of Virulent Listeria monocytogenes and Cronobacter sakazakii in Dairy Cattle, the Environment, and Dried Milk with the In Vitro Application of Natural Alternative Control

Abstract

This study aims to detect the prevalence and antimicrobial resistance of <i>Listeria monocytogenes</i> and <i>Cronobacter sakazakii</i> in three dairy households and dried milk from different suppliers, and evaluate the antimicrobial effect of rose water, rose, and orange essential oils. In total, 360 samples were collected from cattle, the environment, and dried milk (<i>n</i> = 30). Antimicrobial activity was evaluated with twofold microtube dilution and the time-kill method. <i>L. monocytogenes</i> was identified in all households (13.3%) with a prevalence in the range of 5.8-17.5%, while <i>C. sakazakii</i> was identified in one household (5.3%). The former and latter pathogens were highly isolated from the feces at 20% and 2.5% and bedding at 12.5% and 1.6%, respectively. <i>L. monocytogenes</i> was isolated only from milk at 7.5%, but <i>C. sakazakii</i> was not detected in either milk or dried milk. <i>L. monocytogenes</i> strains were screened for virulence genes (<i>iap, hylA,</i> and <i>actA</i>). All strains were positive for the <i>iap</i> gene, while for <i>hlyA</i> and <i>actA</i>, the percentages were (35.4% 16.6%, respectively). <i>L. monocytogenes</i> strains showed high resistance against sulfamethoxazole-trimethoprim (100%), followed by gentamicin, penicillin, and imipenem (95.8%, 95.8%, and 91.6%, respectively). All <i>C. sakazakii</i> strains were susceptible to all tested antibiotics. The bactericidal activity of orange oil was the strongest, appeared after 1 h for both pathogens, followed by rose oil and then rose water.