Abstract
BackgroundSow endometritis is a common disease in pig breeding farms after artificial insemination, which leads to gray-green vaginal secretions and decreased conception rates. It is important to perform an etiologic diagnosis for effective treatments and control of diseases. The aim of this study was to carry out a pathogenic detection in five specimens of vaginal secretions collected from sick pigs with endometritis, implement identification of the pathogens by phenotypic detection and 16 s rDNA sequence and phylogeny analysis, and determinate antibiotic susceptibility of the isolates.ResultsA Streptococcus strain was isolated and identified from all of the five specimens. The isolate was positive for Voges-Proskauer (V-P) and for the hydrolysis of arginine, esculin and myelin-associated glycoprotein (MAG). Acid formation was observed for sorbitol, mushroom sugar, sucrose, and glucose. The 16S rDNA sequence of the isolate possessed 99.93% similarity to that of Streptococcus porcinus. The phylogenetic analysis of 16S rDNA sequence showed that the isolate belonged to the same clade as the S. porcinus strains from humans, pigs, and other animals. The isolate exhibited multi-drug resistance to aminoglycosides, quinolones, macrolides and tetracyclines except being sensitive to some β- lactams such as penicillin G, cephalothin, cefazolin, cephradine and cefuroxime.ConclusionsA S. porcinus isolate with multi-drug resistance was identified from vaginal secretions of sows with endometritis in one pig breeding farm, which suggests that the sow endometritis was caused by S. porcinus infection during artificial insemination. This study indicates that sensitive antibiotics such as penicillin G or some cephalosporins could be used for treatment of the diseases. In addition, the study hints that bacterial multi-drug resistance is a tough problem for disease treatment in pig farms.
Highlights
Sow endometritis is a common disease in pig breeding farms after artificial insemination, which leads to gray-green vaginal secretions and decreased conception rates
S. porcinus is usually detected in pig tonsils. 19.5% of tonsils of the pigs in slaughterhouses were positive for the isolation of S. porcinus, which is just less than the prevalence of S. suis infections (53.7%) [12]
The bacterial isolates showed a poor growth on ordinary nutrient agar with fewer small tipsized colonies, but a good growth on blood agar and serum agar plates with off-white, smooth-surfaced, and regular-edged microcolonies
Summary
Sow endometritis is a common disease in pig breeding farms after artificial insemination, which leads to gray-green vaginal secretions and decreased conception rates. The species Streptococcus porcinus belonging to the genus Streptococcus is commonly associated with pyogenic infections, abortion and endocarditis of pigs, as well as genitourinary tract infection of women [7,8,9]. S. porcinus was first identified in pigs in 1984, and isolated from bovine milk [7, 8]. S. porcinus is usually detected in pig tonsils. 19.5% of tonsils of the pigs in slaughterhouses were positive for the isolation of S. porcinus, which is just less than the prevalence of S. suis infections (53.7%) [12]. Swine S. porcinus causes pig lymph node abscess, throat abscess, pneumonia, arthritis, and endocarditis, as well as sow abortion [1, 8, 13, 14], but there are rare reports on sow endometritis caused by S. porcinus
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