Characterization of Pasteurella multocida isolated from dead rabbits with respiratory disease in Fujian, China

BACKGROUND: Pasteurella multocida is one of the important pathogens that infect rabbits, causing major economic losses in commercial rabbit farming. In this study, 205 P. multocida isolates recovered from lungs of dead rabbits with respiratory disease were defined by capsular serogroups, lipopolysaccharide (LPS) genotypes, multi-locus sequence types and screened virulence factors by using PCR assays, and tested antimicrobial susceptibility. RESULTS: The 205 isolates were assigned into 2 capsular types, A and D, and 2 LPS genotypes, L3 and L6. When combining capsular types with LPS genotypes, 4 serotypes were detected. A:L3 (51.22%, 105/205) was the most predominant serotype, followed by A:L6 (24.88%, 51/205), D:L6 (19.02%, 39/205) and D:L3 (4.88%, 10/205). The 205 isolates were grouped into 3 sequence types, ST10, ST11 and ST12. ST12 (56.10%, 115/205) was the most prevalent sequence type, followed by ST10 (24.88%, 51/205) and ST11 (19.02%, 39/205). In the 205 isolates, virulence associated genes ptfA, fur, hgbB, ompA, ompH and oma87 were positive in the PCR screening, whereas the toxA and tbpA genes were negative. Notably, the 156 capsular serogroup A isolates carried the pmHAS gene. All the 205 isolates were susceptible to most of the used antibiotics, except for streptomycin, gentamycin, kanamycin and ceftriaxone, and the resistance rates of which were 27.80, 15.61, 9.27 and 2.44%, respectively. CONCLUSIONS: This study, for the first time, described the prevalence and characteristics of P. multocida causing respiratory disease in rabbits in Fujian Province, which might be useful for tracking the epidemic strains and development of efficient vaccines and methods to prevent and control the pathogen.