Historically, the use of antibiotics was not well regulated in veterinary medicine. The emergence of antibiotic resistance (ABR) in pathogenic bacteria in human and veterinary medicine has driven the need for greater antibiotic stewardship. The preservation of certain antibiotic classes for use exclusively in humans, especially in cases of multidrug resistance, has highlighted the need for veterinarians to reduce its use and redefine dosage regimens of antibiotics to ensure efficacy and guard against the development of ABR pathogens. The minimum inhibitory concentration (MIC), the lowest concentration of an antibiotic drug that will prevent the growth of a bacterium, is recognised as a method to assist in antibiotic dosage determination. Minimum inhibitory concentrations sometimes fail to deal with first-step mutants in bacterial populations; therefore dosing regimens based solely on MIC can lead to the development of ABR. The mutant prevention concentration (MPC) is the minimum inhibitory antibiotic concentration of the most resistant first-step mutant. Mutant prevention concentration determination as a complementary and sometimes preferable alternative to MIC determination for veterinarians when managing bacterial pathogens. The results of this study focused on livestock pathogens and antibiotics used to treat them, which had a MIC value of 0.25 µg/mL for enrofloxacin against all 27 isolates of Salmonella typhimurium. The MPC values were 0.50 µg/mL, with the exception of five isolates that had MPC values of 4.00 µg/mL. The MPC test yielded 65.52% (18 isolates) Salmonella isolates with florfenicol MICs in the sensitive range, while 11 isolates were in the resistant range. Seventeen isolates (58.62%) of Pasteurella multocida had MIC values in the susceptible range and 41.38% (12 isolates) had an intermediate MIC value. Mutant prevention concentration determinations as done in this study is effective for the antibiotic treatment of bacterial infections and minimising the development of resistance. The MPC method can be used to better control to prevent the development of antibiotic drug resistance used in animals.

Salmonellosis is one of the most important problems in poultry industry and a critical food safety hazard. In the present study the prevalence of avian Salmonellosis was studied in different farms of broiler chickens in Beni Suef Governorate, Egypt during the period from January to April 2020. A total of 140 samples were taken from slaughtered diseased or freshly dead broiler chickens aged from one to 35 days. Bacteriological examination revealed that 7.14% of the samples were Salmonella positive. Serotyping of Salmonella isolates showed that S. kentucky, S. blegdam and S. virchow were recognized at rates of 40%, 30% and 30%, respectively. Antimicrobial susceptibility test revealed that all salmonella isolates were multidrug resistant (MDR). All isolates were resistant to oxytetracycline (100%) while 90% were resistant to amoxicillin-clavulanic acid, cefotaxime, sulfamethoxazole- trimethoprim and norofloxacin. On the other hand, 80% of isolates were sensitive to fosfomycin and nitrofurantoin. Results of screening of some MDR isolates by multiplex PCR for detection of some virulence genes showed that all the tested isolates (100%) had invA, stn, spvC genes meanwhile pefA was not detected in any isolate.

Bacterial contamination has been proven to be common in a variety of foods, especially meats. For this reason, this study was conducted to evaluate the bacteriological quality of imported chilled meat traded in Port-Said markets where 64 random samples of chilled meats represented by 28 imported chilled beef meat samples from lots arrived at Port-Said port (un-marketed) and 36 imported chilled beef meat samples collected from retailed markets at Port-Said governorate (marketed). Samples were analyzed for their total aerobic count., Enterobacteriaceae count, E. coli, total staphylococcus, and S. aureus counts and detection of salmonellae. The total bacterial count recorded an average of 10.73x104 and 2.5x106 in un-marketed and marketed chilled meat respectively. The results showed that 18 out of 64 meat samples were positive for Enterobacteriaceae and 6 samples out of them were unaccepted for human consumption. The incidence of E. coli was in 6 samples from the examined chilled samples, and the 6 were unaccepted. For staphylococcus, there were 24 positive samples, and 13 out of them were unaccepted and for S. aureus, 4 samples out of 64 samples were positive and 4 samples were unaccepted for consumption. Two samples out of 64 were positive for salmonella and considered unfit for human consumption. The obtained results confirmed the poor bacteriological quality of some imported chilled meat that is marketed in Port-Said retailed markets which is related to unhygienic transportation methods until reach the retailed markets.