Study on isolation and antibiotic susceptibility determination of Haemophilus parasuis isolated from disease suspected pigs in some northern provinces, Viet Nam

Abstract

The aim of this study was to isolate Haemophilus parasuis which caused Glasser disease in pigs, and
to evaluate the susceptibility of the isolated strains to common antibiotics using disk diffusion method.
A total of 31 isolates of H. parasuis were isolated from 58 suspected pigs in Ha Noi City, Phu Tho, Bac
Ninh, Hung Yen, Thanh Hoa, and Ha Nam provinces. All H. parasuis colonies were small, transparent,
and non-hemolytic, gram negative, pleomorphic rod from short to long bacilli with the major biochemical
characteristics of catalase and oxidase positive, indole and urease negative, and V factor dependence;
fermentation of glucose, sucrose, fructose; while non-fermenting to mannitol, lactose; and were unable
to grow on MacConkey agar. All 31 strains were positive for H. parasuis by PCR method. Antibiotic
susceptibility test demonstrated that H. parasuis strains were highly susceptible to cefotaxime, cefuroxime,
ceftiofur, amoxicillin/clavulanic acid, florfenicol. While most of the isolated strains were resistant to the
trimethoprime/sulfamethoxazol, penicillin and tilmicosin. The isolated strains were susceptible relatively
high to synthetic antibiotics including: florfenicol-doxycycline, penicillin - streptomycin, gentamicin -
tylosin. The results of this study will be the basis for further studies on serotyping, pathogenicity, and play
an important role in the development of effective prevention measures