Pasteurella multocida is a gram negative and opportunistic pathogen and common inhabitant of the upper respiratory tract of domesticated and wild animal species. It is a causative agent of numerous important diseases worldwide, such as enzootic Purulent bronchopneumonia in Ruminants, and haemorrhagic septicemia in cattle and buffalo. The present study was undertaken to determine the occurrences of Pasteurella multocida carriers in cattle and buffalo slaughtered and also referred to the Veterinary Teaching Hospital of Ahvaz, PCR-serogrouping and antibiotic susceptibility status of isolates detected.
Nasopharyngeal and nasal swabs were collected from 227 cattle and 174 buffalo. The swabs were transferred to the laboratory where the swabs were streaked onto MacConkey agar and sheep blood agar and incubated for 24-48 h at 37 °C. The presumptive colonies were identified based on standard biochemical testing and presumptive P. multocida isolates were further confirmed by PM-PCR based on pasteurella multocida Specified kmt1 gene. A multiplex PCR was used to determine the five pathogen serogroups (A, B, D, E, and F). Antimicrobial susceptibility of P. multocida isolates was determined using the Kirby–Bauer disc diffusion method after culture on Mueller Hinton agar supplemented with 5% sheep blood using commercial antibiotic disk. The result showed that of the 401 tested samples, P. multocida was recovered from 10/227 (4.4%) and 12/174 (6.89%) specimens from cattle and buffalo, respectively. Of the 22 P. multocida isolates, 15 (68.18%) belonged to serogroup A, 5 (22.72%) to serogroup D and two (9.09%) isolates were untypeable. No isolate belonged to B, E and F serogroup. From 10 bovine P. multocida isolates, 7(70%) belonged to serogroup A, 2 (20%) to serogroup D and one (10%) isolate was untypeable. From 12 buffalo P. multocida isolates, 8(66/66%) belonged to serogroup A, 3 (25%) to serogroup D and one (8.33%) isolate was untypeable.
The resistance pattern of P. multocida to the 15 antibiotics examined in this study showed that all P. multocida isolates were sensitive to nitrofurantoin, florfenicol, ciprofloxacin, enrofloxacin, trimethoprim-sulfamethoxazole, oxytetracycline and ceftriaxone. The most common finding was resistance to tylosin (90.9%), followed by resistance to oxacillin (54.54%), streptomycin (45.45%), ampicillin (27.27%), erythromycin (13.63%) and penicillin (9.1%). Also according to the results of antibiotic susceptibility status, fluoroquinolone and florfenicol group antibiotics are recommended for successful treatment of Pasteurellosis.