ABSTRACT
AIM: The aim of this work was to detect antibiotic resistance in Gram-negative bacteria isolated from subclinical mastitis in cattle in West Bengal. MATERIALS AND METHODS: The milk samples were collected from the cattle suffering with subclinical mastitis in West Bengal. The milk samples were inoculated into the nutrient broth and incubated at 37°C. On the next day, the growth was transferred into nutrient agar and MacConkey agar. All the pure cultures obtained from nutrient agar slant were subjected to Gram-staining and standard biochemical tests. All the bacterial isolates were tested in vitro for their sensitivity to different antibiotics commonly used in veterinary practices. All Gram-negative isolates including positive control were subjected to polymerase chain reaction (PCR) for detection of blaCTX-M, blaTEM, blaSHV, blaVIM, tetA, tetB, tetC, and tetM genes considered for extended-spectrum ß-lactamase (ESBL), metallo-ß-lactamase, and tetracycline resistance. RESULTS: In total, 50 Gram-negative organisms (Escherichia coli, Proteus, Pseudomonas, Klebsiella, and Enterobacter) were isolated from milk samples of subclinical mastitis infected cattle. Among these Gram-negative isolates, 48% (24/50) were found either ESBL producing or tetracycline resistant. Out of total 50 Gram-negative isolates, blaCTX-M was detected in 18 (36%) isolates, and 6 (12%) harbored blaTEM genes in PCR. None of the isolates carried blaSHV genes. Further, in this study, 5 (10%) isolates harbored tet(A) gene, and 8 (16%) isolates carried tet(B) gene. No tet(C) gene was detected from the isolates. CONCLUSION: This study showed emerging trend of antibiotic-resistant Gram-negative bacteria associated with subclinical mastitis in cattle in West Bengal, India.
ABSTRACT
Infectious Bovine Rhinotracheitis (BoHV-1) is the most important emerging disease of cattle in India. With an aim to reactivate BoHV-1 from latently infected sero-positive cattle for molecular characteristics of the isolates prevalent in tropical and sub-tropical countries like India and further epidemiological investigations on IBR infections this study had been conducted. Artificial stress with dexamethasone at the dose rate of 0.1 mg kg(-1) body weight for 5 consecutive days was induced in BoHV-1 sero-positive cows. Then isolation from nasal swabs was attempted in Madin Darby Bovine Kidney (MDBK) cell line to find out the prevalent strain in India. The virus was isolated from all the three cows. All the three isolates were typed as BoHV-1.2 (Strain India 4, India 5 and India 6). The reactivation obtained in this study with dexamethasone suggests the usefulness of BoHV-1 cow latency model for epidemiological investigations on BoHV-1 infections in tropical and sub-tropical countries like India, Pakistan etc.
