Isolation and Antimicrobial Resistance Profiles of Culturable Bacteria from Pneumonic Lungs of Diseased Pigs in Jiangxi Province, China

Porcine respiratory disease complex (PRDC) causes substantial economic losses in swine production. This study aimed to investigate culturable bacterial pathogens and their antimicrobial resistance profiles in pneumonic lungs from pigs with clinical PRDC in Jiangxi Province, China. From January 2022 to February 2026, 372 pneumonic lung samples were collected from diseased or dead pigs across 11 cities. Bacteria were recovered from 173 of 372 samples (46.5%), and a total of 218 bacterial strains were identified. Escherichia coli was recovered from 16.9% of samples, followed by Streptococcus suis (14.8%) and Pasteurella multocida (6.5%). E. coli exhibited high resistance to sulfamethoxazole–trimethoprim (95.2%), chlortetracycline (92.1%), ampicillin (90.5%) and florfenicol (88.9%). All E. coli isolates (100.0%) were multidrug-resistant, and phenotypically carbapenem-resistant E. coli was detected. S. suis remained susceptible to β-lactams but was highly resistant to macrolides and tetracyclines. P. multocida exhibited low resistance to most tested drugs. This study is limited by the absence of viral and mycoplasmal detection, convenience sampling, and restriction to culturable bacterial species. The findings support prudent antimicrobial use and strengthening of long-term antimicrobial resistance surveillance, and provide baseline data for further studies on PRDC epidemiology and control in the region.