Antibiotic Resistance of Escherichia coli and Salmonella Species Isolated from Table Eggs in Morocco

Abstract

The development of antimicrobial resistance has become a severe global public health emergency. Foods of animal origin are considered possible drivers of resistant bacteria, including Escherichia coli (E. coli) and Salmonella spp. It is associated with the indiscriminate use of antibiotics, resulting in the inability to treat patients infected with antibiotic-resistant pathogens and a high risk of transmission of these resistant pathogens. The current study aimed to determine the prevalence and antibiotic resistance of E. coli and Salmonella spp. in raw table eggs in Morocco. A total of 870 table eggs resulting from 290 samples (3 eggs = 1 sample), were purchased from ambulatory sellers, street vendors, kiosks, and neighborhood markets from different cities in Morocco and transferred to the laboratory in the Hassan II Agronomy and Veterinary Medicine Institute of Rabat, Morocco. The egg shells and contents were tested separately then the isolation and identification of bacterial pathogens were performed according to the Moroccan Standard Norms. The bacterial isolates were tested for susceptibility to six commonly used antibiotics, namely nalidixic acid (30 µg), kanamycin (30 µg), gentamycin (15 µg), ciprofloxacin (15 µg), tetracycline (30 µg), and amoxicillin (10 μg). The findings revealed that 38 samples (13%) tested positive for E. coli of which 9% were on egg shells, and 4% were in egg content, while for Salmonella enteritidis (S. enteritidis), 5 samples (2%) tested positive and only in the egg contents. Escherichia coli showed the highest resistance to amoxicillin, followed by tetracycline and nalidixic acid with 92.10%, 84.21%, and 50%, respectively, and was sensitive to ciprofloxacin (84.21%), kanamycin (65.79%), and gentamicin (60.54%). Salmonella enteritidis had the highest resistance against tetracycline (80%), followed by ciprofloxacin and nalidixic acid with 40% each. The highest sensitivity rates of S. enteritidis were for gentamicin, amoxicillin, and kanamycin at 80%, 80%, and 40%, respectively. Given that these resistant bacteria could potentially be transferred to humans through eggs or egg products, it is necessary to employ strict hygiene measures and provide a wise and legal use of antibiotics in animal breeding.