Isolation and identification of a porcine-derived Enterococcus strain and analysis of its pathogenicity characteristics
He Qingfeng
You Ying
Guo Wenchao
Guo Dongyu
Li Wei
Peng Wenjing
Tang Feng
Abstract：The aim of this study was to identify the pathogenic bacteria causing diarrhea in piglets at a pig farm in Shenyang,Liaoning Province,and to further analyze its drug resistance and pathogenicity characteristics.Fecal samples from diarrhea piglets at the farm were collected under sterile conditions,and the pathogenic bacteria were identified by methods such as isolation and purification,Gram staining,MALDI-TOF MS and 16S rRNA gene sequencing.Combined with drug sensitivity tests,the drug resistance of the pathogen was investigated by exploring its resistance genes and mobile genetic elements.The pathogenicity of the pathogen was explored by comparing virulence genes,lethal tests with the large wax moth and mouse pathogenicity tests.The results showed that the isolated strain formed a milky,opaque circular colony on the BHIA medium;Microscopic examination revealed that the bacteria were blue-purple,oval or round,arranged singly,in pairs or in short chains;MALDI-TOF MS identified it as Enterococcus faecalis;By 16S rRNA gene sequence comparison,the isolate was more than 99％similar to the published Enterococcus faecalis sequences,and was identified as Enterococcus faecalis and named HS1.The isolate was sensitive to ampicillin,ciprofloxacin,etc.four antibiotics,and resistant to erythromycin,tetracycline,etc.five antibiotics,and carried various resistance genes such as aac(6'),erm(A),tet(M),etc.,and various virulence genes such as cyl,gelE,efaA,etc.The isolate could cause all large wax moth larvae to completely blacken and die within 12 hours,demonstrating strong pathogenic potential;After inoculation in mice,diarrhea occurred,and after autopsy,obvious lesions were found in the cecum and colon,indicating that the isolate had strong pathogenicity.The study showed that the diarrhea of piglets in this pig farm was caused by a multi-drug-resistant and highly pathogenic Enterococcus faecalis strain.The results provide a reference for the prevention and control of piglet diarrhea caused by Enterococcus,clinical rational drug use and related epidemiological research.
Keywords：PigEnterococcus faecalisIsolation and identificationDrug resistancePathogenicity
Publication Date：2026-02-15
Online Publishing Date：2026-03-16(First online date of this platform, not the publication date of the document)
Pages：7( 1-7 )