title: Biofilm formation in Haemophilus parasuis: relationship with antibiotic resistance, serotype and genetic typing.
abstract: Biofilms are surface-associated microbial communities, which are encased in self-synthesized extracellular environment. Biofilm formation may trigger drug resistance and inflammation, resulting in persistent infections. Haemophilus parasuis is the etiological agent of a systemic disease, Glässer's disease, characterized by fibrinous polyserositis, arthritis and meningitis in pigs. The purpose of this study was to examine the correlation between biofilm and antibiotic resistance among the clinical isolates of H. parasuis. In the present study, we tested biofilm-forming ability of 110 H. parasuis isolates from various farms using polystyrene microtiter plate assays. Seventy-three isolates of H. parasuis (66.4%) showed biofilm formation and most of them performed weak biofilm-forming ability (38/73). All isolates were tested for antimicrobial susceptibility to 18 antimicrobial agents by the broth microdilution method. H. parasuis isolates showed very high resistance (>90%) to sulfanilamide, nalidixic acid, and trimethoprim. Resistance to eight antibiotics such as penicillin (41.1% vs 8.1%), ampicillin (31.5% vs 8.1%), amoxicillin (28.8% vs 5.4%), gentamicin (46.6% vs 24.3%), cefazolin (19.2% vs 2.7%), doxycycline (19.2% vs 8.1%), cefotaxime (11% vs 2.7%), and cefaclor (13.7% vs 5.4%) was comparatively higher among biofilm producers than non-biofilm producers. Pulsed-field gel electrophoresis (PFGE) analyses could distinguish various isolates. Our data indicated that H. parasuis field isolates were able to form biofilms in vitro. In addition, biofilm positive strains had positive correlation with resistance to β-lactams antibiotics. Thus, biofilm formation may play important roles during H. parasuis infections.
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China.
authors: Jianmin
authors: J
authors: Zhang
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China.
authors: Chenggang
authors: C
authors: Xu
authors: The Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
authors: Haiyan
authors: H
authors: Shen
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China.
authors: Jingyi
authors: J
authors: Li
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China.
authors: Lili
authors: L
authors: Guo
authors: Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA.
authors: Guojie
authors: G
authors: Cao
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China.
authors: Saixiang
authors: S
authors: Feng
authors: Key Laboratory of Animal Disease Control and Prevention of the Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and control of Guangdong, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, China. Electronic address: mliao@scau.edu.cn.
authors: Ming
authors: M
authors: Liao
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006192:Haemophilus Infections / Q000188:drug therapy / Q000235:genetics / Q000662:veterinary; D044137:Haemophilus parasuis / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D066298:In Vitro Techniques; D015995:Prevalence; D065288:Serogroup; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000235:genetics / Q000276:immunology; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D047090:beta-Lactams
keywords: Antibiotic resistance; Genotyping; Haemophilus parasuis; Pulsed-field gel electrophoresis; Serotype