Molecular epidemiology and characterization of antibiotic resistance of Pasteurella multocida isolated from livestock population of Punjab, Pakistan.

Haemorrhagic septicaemia (HS) is an acute and life-threatening infection of livestock population caused by Pasteurella multocida (P. multocida), responsible for huge mortality, morbidity and production losses. The increase in antibiotic resistance is a growing concern, posing a significant threat to animals and public health. There is limited data on P. multocida disease burden, serotypes, antibiotic susceptibility, and resistance gene profiles in Pakistan. In the current study, 1017 nasal swabs from haemorrhagic septicaemic cattle and buffaloes were collected to isolate P. multocida through microbiological and molecular methods. Susceptibility against commonly used antibiotics was performed and antibiotic resistance genes were evaluated. A prevalence rate of 7.57% was found, where buffaloes were more prone to infection (8.3%) as compared to cows (6.7%). Molecular and sequence analysis confirmed P. multocida isolates in 94.8% (73/77) of samples. Capsular typing revealed all isolates belong to serotype B. Antibiogram analysis showed that enrofloxacin 85.7% (66/77) and ceftiofur 56/77 (72.7%) were the most effective antibiotics. The highest resistance was observed against trimethoprim/sulfamethoxazole 54/77 (70.1%), followed by erythromycin 52/77 (67.5%). Most of the isolates (31.5% (23/73)) carried β-lactamase resistance genes (bla TEM n = 10, bla ROB-1 n = 6, bla OXA-2 n = 5, bla NDM n = 2) followed by trimethoprim/sulfamethoxazole (sul2) resistance genes (26% (19/73)). The current study indicates that HS is consistently circulating among the animal population in Punjab, Pakistan. The current scenario of higher resistance in P. multocida needs continuous surveillance of the infection and mass awareness programs about the non-prescribed and excessive use of antibiotics in the animal sector.