Ceftiofur is primarily approved for the treatment of respiratory tract infections in foodproducing animals. The rise of ceftiofur resistance among Enterobacteriaceae has allegedly
been attributed to the misuse and abuse of this popular antibiotic. In this study, we aimed
to investigate the prevalence and antimicrobial susceptibility profiles of ceftiofur-resistant
Enterobacteriaceae in raw milk and kareish cheese samples collected from Menoufia
governorate, Egypt. A total of 80 samples, 40 each of raw cow's milk and kareish cheese,
were analyzed by enrichment in Enterobacteriaceae enrichment broth supplemented with
ceftiofur (8 µg/ml) and plated on violet, red bile glucose agar plates with ceftiofur (8
µg/ml). The isolates were subjected to antimicrobial susceptibility testing against 10
antibiotics. The study found that 90% of raw cow's milk samples and 95% of kareish
cheese samples had ceftiofur-resistant Enterobacteriaceae. Higher resistance rates to
cefepime (80.95%), cefotaxime (95.24%), and ceftriaxone (95.24%) were found among
raw milk isolates compared to ciprofloxacin (69.05%) and oxytetracycline (52.38%).
Conversely, ceftazidime (14.29%), gentamicin (2.38%), meropenem (2.38%), and colistin
(2.38%) showed lower resistance rates. Similarly, Enterobacteriaceae isolates of kareish
cheese samples showed high resistance rates to cefepime (97.61%), ceftriaxone (78.57%),
cefotaxime (71.43%), oxytetracycline (71.43%), and ciprofloxacin (69.05%), but
low resistance rates to gentamicin (11.90%) and ceftazidime (9.52%). No resistance was
observed to meropenem and colistin. Our findings suggest that raw milk and karish cheese
may serve as potential reservoirs for the transmission of ceftiofur-resistant
Enterobacteriaceae to humans. It is critical to monitor the frequency of ceftiofur-resistant
bacteria in food items and modify the legislation controlling the use of ceftiofur in food
animals.