A comparison of the lytic activity of poultry, human, and bovine phages with staphylococci of different origin.

The total of 625 staphylococcal strains of different origin were typed with 22 Shimizu's poultry phages. For comparison all these strains were also investigated with the 24 phages of the international basic set for typing human staphylococci and with the 12 phages for typing bovine staphylococci. Of the 325 Staphylococcus aureus strains 50 from humans belonged to A biotype, 100 from chickens to B biotype and further 175 animal strains (of swine, rabbit, bovine, sheep, and hare provenance) to B, C, and D biotypes. Lytic activity of the poultry phages used at routine test dilution showed marked specificity related to the chicken strains were lysed. They were predominantly susceptible to phages CH4, CH14, CH15, CHA1, CHA2, CHA3, and CHA4. Most of the strains thus belonged to phage group I (74.0%), the others to phage groups II and III (18.0% and 2.0%). The examined strains of the other origins were either typable only sporadically (human in 4.0%, rabbit and bovine in 6.7%) or completely resistant. When the poultry phages were used at 100 x RTD the number of typable strains increased more significantly only in swine, rabbit, and bovine strains (23.3%, 60.0%, and 56.6%). On the contrary, human and bovine phages lysed chicken strains merely in 14.0% and 1.0% at RTD and in 20.0% and 3.0% at 100 x RTD respectively. All the 200 Staphylococcus intermedius and 100 Staphylococcus hyicus strains were resistant to the used 58 phages at RTD. When examined at 100 x RTD three Staph. hyicus strains were typable with the group IV phage CH11 from the poultry set, only.