Molecular and Immunological Evaluation of Some Bacteria Causing Calf Diarrhea

One issue that intensive farming has to deal with is neonatal calf diarrhea, and probiotics are seen to be a viable solution to improve the health of calves. The aim of this study was to assess the effects of short-term administration of an antibiotic or probiotic to diarrheal calves on total leukocytic count, serum bactericidal activity, and phagocytosis, as well as to identify potential bacteria that may cause calf diarrhea in early life stages. 55 diarrheal calves, ranging in age from 1 to 20 days, were sampled for feces at a private dairy farm in the Sharkia governorate. E. coli, Salmonella spp., and Clostridium species were among the isolated bacteria, with prevalence rates of 58.2%, 8%, and 12%, respectively. The O26, O111, O119, O128 and O125 serogroups of E. coli isolates were the identified serotypes. While S. Typhimurium and S. Enteritidis were the recovered Salmonella serotypes. The results of the polymerase chain reaction (PCR) showed that the invA gene was amplified in the four salmonella isolates but the phoA gene was amplified in all E. coli isolates. Since only the alpha toxin gene was present in each isolate of C. perfringens, they were all type A. Antibiogram test results showed that most isolated species were multi-drug resistant to the ten commonly used antibiotics. On the other hand, isolates of E. coli, salmonella, and clostridium that demonstrated sensitivity for amoxicillin with percentages of 93.3%, 100%, and 66.7%, respectively, represented the medicine that was most successful. Regardless of infection, probiotic or antibiotic treatment, the total leukocytic count values in all diarrheal calves were considerably greater than those in the control group. Serum bactericidal activity in probiotic-treated calves was significantly higher than in the control and antibiotic-treated groups, while it was significantly lower in the antibiotic-treated group. Calf polymorphonuclear leukocytes treated with antibiotics or probiotics had considerably increased phagocytic activity than the control group. In conclusion, probiotics supplementation is an effective strategy for the prevention and control of calf diarrhea

Genes Contributed on Biofilm Forming Bacteria Incriminated in Various Disease Conditions in Cattle

Biofilm production is a complex process that occurs as a series of molecular and physiological events; bacteria employ biofilms as a physical barrier to shield themselves from antimicrobial agents. In this study, biofilm-forming bacteria were isolated from the lung, heart, spleen, and liver of diseased cattle after slaughter.  Out of 210 examined samples, 82 samples were positive for biofilm forming ability either by Cong red binding assay or by tube method. The 82 isolates were identified as 27 E. coli strains belonging to O146:H21, O26:H11, O55:H7, O111:H2, O127:H6, O124:H2, O153:H1, and O111:H4, 23 isolates were identified as S. aureus, 15 as K. pneumoniae belonging to K1(HVKP), K2 (HVKP), K1 (CKP), and K2 (CKP) and 3 strains as K. oxytoca. Besides, 14 strains were identified as P. aeruginosa belonging to O6 (G), O11 (E), and O2 (B). Results showed that E. coli and P. aeruginosa isolates were positive for all tested biofilm-related genes whereas mkrA and spaA genes were the most commonly detected genes among K. pneumoniae and S. aureus isolates, respectively. Isolates showed a high level of antimicrobial resistance (AMR) to most tested antimicrobial agents. Macroscopical examination of the affected organs showed that the lung lost its spongy texture; the spleen was darkened and enlarged in addition to congestion of the liver and heart.  Microscopical findings showed that the liver and heart were congested with leucocytic cells infiltrations while the lung showed peribronchial hypercellularity, excessive interstitial and alveolar cellular infiltration with severe congestion and degeneration of alveolar epithelial cells, destruction of alveoli with lymphocytic cells infiltration and collapsed alveoli with fibrous tissue proliferation while spleen exhibited marked congestion with aggregation of bacterial colonies either focal or diffuse, necrosis was also detected.