Identification And Biological Characterization Of Haemophilus Parasuis Isolated From Shaanxi Province

Haemophilus parasuis (Hps) is one of the most prevalent colonizers of the upperrespiratory tract of pigs in age from2weeks to4months, especially5to8weeks. Hps is thecausative agent of Haemophilus parasuis disease, also called Gl sser’s Disease, which ismainly characterized by serofibrinous pleurisy, arthritis and meningitis in clinical piglets. Inrecent years, the incidence and mortality of the disease significantly increased worldwide thatcaused huge economic losses in pig industry.In this study, two strains of Hps were isolated from58clinical samples in Guanzhongarea of Shaanxi province. The cultural characterization, drug sensitive tests, pathogenesis andNAD-dependence were investigated:1.58clinical samples were collected from suspected pigs in12areas of Shaanxi,including Baoji, Hanzhong and Xianyang on June2013to March2014. The samples wereexamined by cultural characterization, morphologic finding, biochemical identification andPCR identification. Two Hps strains have been identified from those samples with commonpolyserositis and arthritis in pigs.2. Difficulty of Hps bacteria culture in vitro hamperes the detection of clinical samples.Our Hps isolates can not grow in ordinary, soytone, peptone and MacConkey agar plates, as wellas in nutrient broth, but can grow very well in the tryptone soy agar (TSA) medium with5%calfserum and0.02%NAD, TSA medium with0.02%NAD and well in chocolate agar medium.However, the two strains can still grow in blood agar plate medium and TSA without anything,which is not eligible for the NAD-dependence of Hps. Additionally, The growth of the twostrains were tested every3hours in tryptone soy broth (TSB) with5%calf serum and0.02%NAD, TSB with5%calf serum and TSB without anything. The statistics of OD600nmtested byUV spectrophotometer showed the number of viable bacteria cultured in3different culturemedia. It’s apparent that both strains can be cultured better in TSB with5%calf serum and0.02%NAD than in TSB with5%calf serum. However, neither strains can be cultured in TSBwithout anything. The phenomenon that our Hps isolates can be cultured well in TSB with5%calf serum was not obedient to the NAD-dependence of Haemophilus parasuis.3. Drug sensitivity tests showed that both strains were100%sensitive to such antibiotics as Cefoperazone, Streptavidin sulfate, Piperacillin utants, Cefazolin, Ambramycin, Oxacillin,Tobramycin, Polymyxin B, Levofloxacin, Chloromycetin and Vancomycin, sensitive toGentamicin, lowly sensitive to Ampicillin and not sensitive to Aztreonam at all. According tothe pathogenesis to mouse, neither can cause incidence and mortality.In conclusion, some biological characterization of our Hps isolates were not obedient toHps that have been investigated and recorded, which can contribute to the research includingmolecular character, pathogenesis and virulence factors, as well as the exploration in the fieldof epidemiology investigation, isolation, prevention, control and treat of the disease inGuanzhong area of Shaanxi Province.