Studies on biochemical, serological and further characteristics of Streptococcus porcinus

Detection of Various Streptococcus spp. and Their Antimicrobial Resistance Patterns in Clinical Specimens from Austrian Swine Stocks

Knowledge of pathogenic potential, frequency and antimicrobial resistance patterns of porcine Streptococcus (S.) spp. other than S. suis is scarce. Between 2016 and 2020, altogether 553 S. spp. isolates were recovered from clinical specimens taken from Austrian swine stocks and submitted for routine microbiological examination. Antimicrobial susceptibility testing towards eight antimicrobial substances was performed using disk diffusion test. All isolates from skin lesions belonged to the species S. dysgalactiae subspecies equisimilis (SDSE). S. hyovaginalis was mainly isolated from the upper respiratory tract (15/19) and S. thoraltensis from the genitourinary tract (11/15). The majority of S. suis isolates were resistant to tetracycline (66%), clindamycin (62%) and erythromycin (58%). S. suis isolates from the joints had the highest resistance rates. S. suis and SDSE isolates resistant to tetracycline were more likely to be resistant to erythromycin and clindamycin (p < 0.01). Results show that different species of Streptococcus tend to occur in specific body sites. Nevertheless, a statement whether these species are colonizers or potential pathogens cannot be given so far. High resistance rates of S. suis towards tetracyclines and erythromycin and high recovery rates of S. suis from lung tissue should be considered when treating pigs with respiratory diseases.

Isolation and characteristics of multi-drug resistant Streptococcus porcinus from the vaginal secretions of sow with endometritis

Background

Sow 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.

Results

A 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.

Conclusions

A 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.

Phenotypic and genotypic characteristics of Streptococcus porcinus isolated from human sources

The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from human sources were investigated and compared to the characteristics of 17 reference strains obtained from nonhuman sources. All of the S. porcinus isolates were beta-hemolytic (wide zones), susceptible to vancomycin, gave positive results for the leucine aminopeptidase and l-pyrrolidonylarylamidase tests, and produced acids from mannitol and sorbitol. Most of them were positive for the CAMP test and resistant to bacitracin. The isolates were susceptible to most of the 14 antimicrobials tested, except for tetracycline, for which 80% of the human isolates and 35.2% of the nonhuman strains were resistant. The tet(M) and the tet(O) genes were detected in 23 (88.5%) and 8 (30.8%) of the 26 tetracycline-resistant isolates, respectively. Analysis of whole-cell protein profiles obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a high similarity among the profiles. Chromosomal DNA was analyzed by pulsed-field gel electrophoresis (PFGE) after digestion with SmaI and by random(ly) amplified polymorphic DNA (RAPD)-PCR using primer 1254. Analysis of SmaI-restricted genomic DNA revealed the substantial genetic diversity among S. porcinus isolates from nonhuman sources, which were also serologically more diverse. Most of the human isolates belonged to serogroup NG1 and shared highly related PFGE profiles that were distinct from profiles of isolates from nonhuman sources. These results were in agreement with those obtained by analysis of amplicons after RAPD-PCR, indicating the potential ability of these techniques for typing S. porcinus and suggesting the occurrence of a few clonal groups of S. porcinus strains adapted to the human host.

Streptococcus porcinus as a cause of spontaneous preterm human stillbirth

We report, to our knowledge, on the first case of a woman suffering stillbirth due to Streptococcus porcinus on the basis of microbiologic and histologic data.

Antimicrobial growth promoters used in animal feed: effects of less well known antibiotics on gram-positive bacteria

There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented.

Identification of streptococci isolated from various sources by determination ofcfbgene and other CAMP-factor genes

In the present study, the CAMP-factor (cfb) gene of streptococci of serological group B (Streptococcus agalactiae) and the CAMP-factor (cfu) gene of S. uberis could be amplified by polymerase chain reaction. A cfb specific amplicon could be observed for all 128 phenotypically CAMP-positive S. agalactiae, for the phenotypically CAMP-negative S. agalactiae strain 74-360, and for 2 S. difficile reference strains. A cfu specific amplicon could be observed for all 7 phenotypically CAMP-positive S. uberis. Four S. agalactiae strains isolated from 4 cows with mastitis appeared to be phenotypically CAMP-negative and negative in the cfb gene PCR. The CAMP-positive and CAMP-negative isolates, including both S. difficile, could be identified as S. agalactiae by amplification of a S. agalactiae specific part of the V2 region of the 16S rRNA and a species-specific part of the 16S-23S rRNA intergenic spacer region. Amplification of an internal fragment of the cfb gene with a reduced annealing temperature yielded positive reactions not only for CAMP-positive S. agalactiae, but also for phenotypically CAMP-positive S. pyogenes (n = 4), S. canis (n = 28), and S. uberis (n = 7), indicating a close relation of the CAMP genes of these 4 species. The relation could be further demonstrated by sequencing the internal fragment of the CAMP-factor (cfg) gene of S. canis and comparing the sequence with those of S. agalactiae, S. pyogenes, and S. uberis.Key words: CAMP factor, cfb, cfu, S. canis.

Species identification of Streptococcus porcinus by restriction fragment length polymorphism analysis of 16S ribosomal DNA

Streptococcus porcinus reference strains and routine isolates belonging to Lancefield's serogroup E, P, U and V and to various serotypes of serogroup E were examined for their 16S ribosomal DNA fingerprint pattern. Oligonucleotide primers complementary to 16S rRNA genes were used to amplify gene fragments by polymerase chain reaction from genomic DNA. The amplified 1450 bp fragment was subsequently digested with the restriction enzyme BpiI resulting in two fragments with a size of approximately 1250 bp and 200 bp. All 45 S porcinus investigated in the present study could be identified on the basis of this characteristic 16S rDNA fingerprint pattern and clearly differentiated from 16 control strains of various species and serogroups of genus Streptococcus. The present results demonstrate the potential application of 16S rDNA analysis for identification of S porcinus, a species which might express various group- and type-specific antigens.