RESUMO
Pathogenic Staphylococcus spp. strains are significant agents involved in mastitis and in skin and limb infections in dairy cattle. The aim of this study was to assess the antibacterial effectiveness of bacteriophages isolated from dairy cattle housing as potential tools for maintaining environmental homeostasis. The research will contribute to the use of phages as alternatives to antibiotics. The material was 56 samples obtained from dairy cows with signs of limb and hoof injuries. Staphylococcus species were identified by phenotypic, MALDI-TOF MS and PCR methods. Antibiotic resistance was determined by the disc diffusion method. Phages were isolated from cattle housing systems. Phage activity (plaque forming units, PFU/mL) was determined on double-layer agar plates. Morphology was examined using TEM microscopy, and molecular characteristics were determined with PCR. Among 52 strains of Staphylococcus spp., 16 were used as hosts for bacteriophages. Nearly all isolates (94%, 15/16) showed resistance to neomycin, and 87% were resistant to spectinomycin. Cefuroxime and vancomycin were the most effective antibiotics. On the basis of their morphology, bacteriophages were identified as class Caudoviricetes, formerly Caudovirales, families Myoviridae-like (6), and Siphoviridae-like (9). Three bacteriophages of the family Myoviridae-like, with the broadest spectrum of activity, were used for further analysis. This study showed a wide spectrum of activity against the Staphylococcus spp. strains tested. The positive results indicate that bacteriophages can be used to improve the welfare of cattle.
RESUMO
The aim of the study was phenotypic and genotypic characterization of Erysipelothrix rhusiopathiae strains isolated from diseased pigs in Poland and comparison of the SpaA (Surface protective antigen A) sequence of wild-type strains with the sequence of the R32E11 vaccine strain. The antibiotic susceptibility of the isolates was assessed using the broth microdilution method. Resistance genes, virulence genes, and serotype determinants were detected using PCR. The gyrA and spaA amplicons were sequenced to determine nonsynonymous mutations. The E. rhusiopathiae isolates (n = 14) represented serotypes 1b (42.8%), 2 (21.4%), 5 (14.3%), 6 (7.1%), 8 (7.1%), and N (7.1%). All strains were susceptible to ß-lactams, macrolides and florfenicol. One isolate showed resistance to lincosamides and tiamulin, and most strains were resistant to tetracycline and enrofloxacin. High MIC values of gentamicin, kanamycin, neomycin, trimethoprim, trimethoprim/sulfadiazine, and rifampicin were recorded for all isolates. Phenotypic resistance was correlated with the presence of the tetM, int-Tn, lasE, and lnuB genes. Resistance to enrofloxacin was due to a mutation in the gyrA gene. All strains contained the spaA gene and several other genes putatively involved in pathogenesis (nanH.1, nanH.2, intl, sub, hlyA, fbpA, ERH_1356, cpsA, algI, rspA and rspB) Seven variants of the SpaA protein were found in the tested strains, and a relationship between the structure of SpaA and the serotype was noted. E. rhusiopathiae strains occurring in pigs in Poland are diverse in terms of serotype and SpaA variant and differ antigenically from the R32E11 vaccine strain. Beta-lactam antibiotics, macrolides, or phenicols should be the first choice for treatment of swine erysipelas in Poland. However, due to the small number of tested strains, this conclusion should be approached with caution.
