Abstract: This study investigated the serotypes and antimicrobial resistance profiles of prevalent Haemophilus parasuis strains on a large?scale pig farm in Guangdong Province. From 2024 to 2025，277 tissue samples（including heart，lung，joint fluid，and pericardial fluid）were collected from deceased pigs suspected of H. parasuis infection. Isolation，purification，serotyping，and antimicrobial susceptibility testing of H. parasuis were conducted. The results showed that 53 strains of H. parasuis were isolated and purified from the samples based on colony characteristics and PCR identification，yielding an isolation rate of 21.2%（53/277）. The predominant serotype was type 5，accounting for 73.58%（39/53），followed by type 1 at 11.32%（6/53）. Antimicrobial susceptibility testing indicated that the isolated strains exhibited relatively high sensitivity to several antimicrobial agents，including β?lactams（amoxicillin，penicillin sodium，cefotaxime，cefazolin，cephalexin，and compound amoxicillin［amoxicillin/clavulanate potassium］），the macrolide tilmicosin，the amphenicol florfenicol，the aminoglycoside neomycin，and the polypeptide colistin sulfate.The findings reveal a complex serotype distribution and severe antimicrobial resistance situation regarding H. parasuis on this farm. This study provides crucial data to support the prevention and control of H. parasuis disease on the farm.

Key words: Large?scale Pig Farm；Haemophilus arasuis；Serotype；Antimicrobial susceptibility

摘要： 该研究旨在摸清广东省某规模化猪场副猪嗜血杆菌流行菌株的血清型及耐药性状 况，2024－2025年从该猪场采集疑似患副猪嗜血杆菌病病死猪的心脏、肺脏、关节液、心包液等 组织样本277份，开展副猪嗜血杆菌的分离纯化、血清型鉴定与药敏试验研究。结果显示，经 菌落特征和PCR 鉴定，该研究从组织样本中分离纯化得到53 株副猪嗜血杆菌，分离率为 21.2%（53/277）。其中，主要优势血清型为5型，占比达73.58%（39/53）；1型占比为11.32%（6/ 53）。药敏试验结果显示，分离菌株对61%以上的药物表现出明显的耐药性，仅10种药物敏感 性高于其他药物，具体包括：β?内酰胺类的阿莫西林、青霉素钠、头孢噻肟、头孢唑啉、头孢氨 苄、复方阿莫西林（阿莫西林/克拉维酸钾）；大环内酯类的替米考星；酰胺醇类的氟苯尼考；氨基 糖苷类的新霉素；以及多肽类的硫酸黏菌素。结果表明，当前该猪场副猪嗜血杆菌流行的血清 型复杂，耐药情况严重，研究为该猪场副猪嗜血杆菌病防控提供了数据支撑。

关键词: 规模化猪场；副猪嗜血杆菌；血清型；药敏试验