Isolation of Staphylococcus species from the tonsils of healthy pigs and phage patterns of isolates

First Molecular Characterization of Siphoviridae-Like Bacteriophages Infecting Staphylococcus hyicus in a Case of Exudative Epidermitis

Exudative epidermitis (EE), also known as greasy pig disease, is one of the most frequent skin diseases affecting piglets. Zoonotic infections in human occur. EE is primarily caused by virulent strains of Staphylococcus (S.) hyicus. Generally, antibiotic treatment of this pathogen is prone to decreasing success, due to the incremental development of multiple resistances of bacteria against antibiotics. Once approved, bacteriophages might offer interesting alternatives for environmental sanitation or individualized treatment, subject to the absence of virulence and antimicrobial resistance genes. However, genetic characterization of bacteriophages for S. hyicus has, so far, been missing. Therefore, we investigated a piglet raising farm with a stock problem due to EE. We isolated eleven phages from the environment and wash water of piglets diagnosed with the causative agent of EE, i.e., S. hyicus. The phages were morphologically characterized by electron microscopy, where they appeared Siphoviridae-like. The genomes of two phages were sequenced on a MiSeq instrument (Illumina), resulting in the identification of a new virulent phage, PITT-1 (PMBT8), and a temperate phage, PITT-5 (PMBT9). Sequencing of three host bacteria (S. hyicus) from one single farm revealed the presence of two different strains with genes coding for two different exfoliative toxin genes, i.e., exhA (2 strains) and exhC (1 strain). The exhC-positive S. hyicus strain was only weakly lysed by most lytic phages. The occurrence of different virulent S. hyicus strains in the same outbreak limits the prospects for successful phage treatment and argues for the simultaneous use of multiple and different phages attacking the same host.

Isolation and species distribution of staphylococci from animal and human skin

From April 1999 to December 2000, a survey was made on the distribution of Staphylococcus species on the skin of 7 kinds of animals and humans. Staphylococci were isolated from 12 (100%) of 12 pigs, 17 (89.5%) of 19 horses, 30 (100%) of 30 cows, 73 (90.1%) of 81 chickens, 10 (40%) of 25 dogs, 23 (76.7%) of 30 laboratory mice, 20 (52.6%) of 38 pigeons, and 80 (88.9%) of 90 human beings. The predominant staphylococci isolated from a variety of animal species were novobiocin-resistant species, S. xylosus and S. sciuri regardless of the animal host species. The novobiocin-resistant species including S. xylosus and S. sciuri were only occasionally isolated from human skin. The predominant staphylococci found on human skin were novobiocin-sensitive species, S. epidermidis (63.8%), followed by S. warneri (28.8%) and S. hominis (13.8%). The results suggest that the staphylococcal flora inhabiting animal skin are different from those of human skin in regard to the predominant species isolated. In this study, we used pulsed-field gel electrophoresis to examine the chromosomal polymorphisms of S. epidermidis isolated most frequently from human skin. Strains of S. epidermidis showed the greatest genomic diversity in their fragment patterns.

Pulsed-field gel electrophoresis of Staphylococcus hyicus and Staphylococcus chromogenes genomic DNA and its taxonomic, epidemiologic and ecologic applications in veterinary medicine

One hundred and thirty-eight strains of Staphylococcus hyicus and 21 strains of S. chromogenes isolated from animals were analyzed by pulsed-field gel electrophoresis (PFGE) after restriction endonuclease Smal digestion of chromosomal DNA. Eighty-eight strains of S. hyicus from pigs with or without exudative epidermitis (EE) generated 16 to 26 fragments in the size range of < 1 to 485 kb, and yielded 39 different patterns. With regard to the strains from pigs with EE, PFGE patterns differed according to the country of origin. Outbreaks of EE occurring on four separate pig farms in Japan involved S. hyicus with different PFGE patterns. The PFGE patterns shown by S. hyicus strains from 4 kinds of animals were compared. Strains from pigs differed from those isolated from chickens (n = 45; 18 to 24 fragments of < 1 to 425 kb), cows (n = 3; 17 to 19 fragments of < 1 to 475 kb), and goats (n = 2; 16 or 17 fragments of < 1 to 1,125 kb). Also, each of the chicken, cow and goat strains had a host-specific fragment. The results suggest that PFGE analysis might be a useful marker for distinguishing ecovars within S. hyicus. In contrast, strains of S. chromogenes from pigs and cows generated 17 to 24 fragments ranging from < 1 to 545 kb. The PFGE patterns of S. chromogenes strains were more highly conserved than those of S. hyicus. S. chromogenes strains could be distinguished from S. hyicus strains by fragments within the range of 305 to 545 kb. The results indicate that PFGE analysis could be used to distinguish between S. hyicus and S. chromogenes. We conclude that PFGE analysis is a useful tool not only for species or strain identification but also for epidemiologic or ecologic studies of S. hyicus and S. chromogenes.

Evaluation of the Staph-Zym-system for identification of Staphylococcus hyicus and Staphylococcus intermedius

The Staph-Zym system was evaluated as a means for identifying cultures of Staphylococcus hyicus isolated from pigs and bovines and cultures of Staphylococcus intermedius isolated from canines. The selected cultures had been identified by conventional methods. The Staph-Zym system correctly identified all 52 S. hyicus and all 33 S. intermedius. It is concluded that the Staph-Zym system is a practical and reliable test for identifying mostly animal pathogenic S. hyicus and S. intermedius, and might possibly be useful for veterinary microbiologists.