Veterinary Research Forum

Abstract Staphylococcus aureus is one of the most common causes of mastitis worldwide. This study aimed to determine the prevalence and antimicrobial resistance (AMR) patterns of S. aureus in mastitic milk samples collected from camel farms in Matrouh Governorate, Egypt. A total of 200 mastitic camel milk samples were evaluated for S. aureus using both conventional culture-based and molecular-based methods. Antibiotic susceptibility testing of S. aureus isolates was conducted using disc diffusion and agar dilution methods, with antibiotic resistance genes identified through polymerase chain reaction with specific primers. Out of samples tested, 60 (30.00%) were positive for S. aureus. The isolates displayed the highest of resistance against piperacillin-tazobactam (55.00%) followed by trimethoprim- sulfamethoxazole (45.00%) and amoxicillin (40.00%). Half of the isolates were multidrug-resistant (MDR). The AMR genes included methicillin-resistant gene (mecA), β-lactamase gene (blaZ), tetracycline resistance gene (tetK), erythromycin resistance gene (ermB) and vancomycin resistant gene (vanA) were detected in 100%, 100%, 95.00%, 90.00% and 20.00% of the isolates, respectively. In conclusion, the presence of MDRS aureus as a cause of clinical camel mastitis is a significant veterinary and public health concern. These findings highlight the importance of proper antibiotic use in Egyptian camel farms and the need for molecular techniques to fully understand the genetic profile of antimicrobial-resistant S. aureus isolates.

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major public health problem. Therefore, this study was aimed to estimate the prevalence of MRSA in various food products. A total number of 204 food samples including raw milk (n = 30), cheese (n = 60), chicken (n = 25), beef (n = 24) and fish (n = 65) were collected from August to November of 2021 within different localities in Kafr El-Sheikh governorate, the northern region of Egypt. All samples were assessed through a series of bacteriological and biochemical techniques to identify MRSA. Out of 204 samples, 52(25.49%) isolates were presumptively identified as MRSA on oxacillin resistance screening agar base media. Of these 52 isolates, 17(32.69%) were characterized as coagulase-positive. For the molecular confirmation of MRSA, all isolates were subjected to polymerase chain reaction assays to detect mecA and mecC. In addition, mecA was identified in all the isolates (100%), whereas, none was positive for mecC. Therefore, based on the detection of mecA, the overall occurrence rate of MRSA among the samples was 8.33%. The isolates were also subjected to antimicrobial susceptibility tests. Cefoxitin, cefuroxime, oxacillin and amoxicillin-clavulanic acid were completely resistant (100%) to the isolates, however, susceptible to vancomycin and ciprofloxacin. Raw milk had the highest prevalence of MRSA (13.30%), followed by chicken (12.00%), fish (9.20%), cheese (5.00%) and beef (4.20%). Due to the possibility of transmission of these strains to humans, the high prevalence of MRSA in various foodstuffs in Egypt poses a potential public health risk.

Abstract Newcastle disease (ND) causes severe economic losses in poultry production. Despite the intensive vaccination regimes of NDV in Egypt, many outbreaks are being reported. The present study focused on the preparation and evaluation of inactivated velogenic Newcastle disease virus vaccine (genotype VII) isolated from Egyptian broiler chicken during 2015-2016. Fifty-five tissue samples including trachea, lung, liver, proventriculus, intestine, and kidney collected from commercial broiler chickens were used for virus isolation in specific pathogen-free embryonated chicken eggs (ECE) and identified using RT-PCR and sequencing. The isolates were classified by sequencing as velogenic NDV genotype VIId containing F0 protein cleavage site motifs (¹¹²RRQKRF¹¹⁷). A selected isolate was served as a master seed for the preparation of inactivated NDV vaccine with or without Montanide ISA70 adjuvant and evaluated in SPF chicks. Nine NDV isolates were isolated on ECE and the highest infectivity titer of the virus was 7.50 log₁₀ EID₅₀ mL^-1 by the 5^th passage. Vaccinated chicks with NDV-Montanide ISA70 adjuvanted vaccine exhibited antibody titer of 5.20 log₂ at the 3^rd-week-post-vaccination (WPV) with the highest titer (8.90 log₂ mL^-1) at the 6^th-WPV. Protective antibodies values were persisted to 12^th WPV followed by a gradual decrease to the end of the experiment (16^th weeks). Vaccination of chicks with inactivated NDV isolate without adjuvant failed to induce protective HI antibodies all over the experiment. Chickens vaccinated with the ISA70 adjuvant vaccine were passed homologous challenge tests with 100% protective efficiency, while the unadjuvanted vaccine could not provide any protective efficiency. In conclusion, the preparation of inactivated oil adjuvant vaccine from NDV field circulating strains was efficient in controlling the disease in Egypt.