Molecular characterization of four strains of Pasteurella multocida isolated from clinical sources

  Objective  To understand the molecular characteristics of four strains of Pasteurella multocida isolated from clinical sources and provide reference for the clinical diagnosis, treatment and prevention and control of clinical infection of Pasteurella multocida.

  Methods  Four strains of P. multocida (P46, P78, P79 and P96) were used for subspecies, capsular, lipopolysaccharide genotype identifications, multi-locus sequence typing (MLST) and virulence analysis by PCR amplification. The genetic relationship of the sequence type (ST) with global strains were analyzed. The susceptibilities of the isolates to antibiotics were tested with K-B method.

  Results  Four strains all belonged to Pasteurella multocida subsp. multocida, capsular type A and lipopolysaccharide type L1. With MLST analysis, strain P46, P78, P79 and P96 were classified as ST20, ST7, ST7 and a new ST (ST429), respectively. All of the strains contained virulence genes fimA, hsf-2, pfhA, hgbA, hgbB, exbBD-tonB, sodC, soda, oma87, omph, nanB and nanH, but contained no ptfA and toxA genes. The genetic evolution analysis showed that four strains clustered with STs from Oceania. The results of antibiotic susceptibility test showed that all the strains were sensitive to ampicillin, penicillin, amoxicillin-clavulanate, ceftriaxone, moxifloxacin, levofloxacin, azithromycin, chloramphenicol, and trimethoprim-sulfamethoxazole, but resistant to erythromycin.

  Conclusion  The isolation of P. multocida from clinical source is increasing, and the clinical infection of P. multocida has become more serious. The molecular characterization of P. multocida should be encouraged to provide better understanding of P. multocida infection epidemics and evidence for its prevention and control.