Analysis of Virulence and Drug Resistance of Glaesserella parasuis Serotype 2

Abstract

【Objective】Glaesserella parasuis (GPS) is the pathogen that causes Gl?sser's disease in pigs. It is one of the most serious bacterial pathogens that harm pig industry. There are many serotypes of this bacterium, and the crossprotection between different serotypes is weak. Serotype 2 is a moderately virulent strain, and the proportion of clinical isolates has been increasing, resulting in increasingly serious harm in recent years. GPS serotype 2 was isolated from nursery pigs in a large-scale pig farm in Henan Province and a series of tests were conducted, and provided reference for scientific prevention and control of the disease.【Method】In this study, lung, trachea, blood and other samples of GPS clinically suspected cases pigs were collected. Bacterial isolation and purification, Gram staining microscopy, routine PCR, guinea pig pathogenicity test, AGAR diffusion drug sensitivity test and other methods were used. Morphological observation, identification, serotyping, virulence gene detection, drug-resistant gene detection, pathogenicity and drug resistance of suspected bacteria were studied.【Result】A strain of GPS was isolated from lung samples and identified as serotype 2. The strain carried virulence genes of vta1, vta2, vta3, wza, ompP2, nanH, cdtA, cdtB, cdtC and espP2, and showed strong virulence to guinea pigs. The strain carried drug-resistant genes aadA1, strA, strB, aphA1, tet(B), sul2, and had strong resistance to penicillin G, kanamycin, amicacin, streptomycin, tetracycline, oxytetracycin, and cotrimoxazole. It had good sensitivity to ceftiofurme, ceftazidime, amoxicillin, ampicillin, levfloxacin, ofloxacin, ennofloxacin and ciprofloxacin, and had significant clinical effect.【Conclusion】The isolates of GPS serotype 2 have strong virulence, can pass through the blood-brain barrier, and have obvious multi-drug resistance. The results of this study provide reference for the epidemiological investigation of GPS serotype 2, pathogenic mechanism, and the formulation of clinical prevention and control measures.

Keywords

• glaesserella parasuis serotype 2
• virulence gene
• pathogenicity
• drug sensitivity test
• drug-resistant gene