Abstract
The purpose of the present study was to investigate sensitivity of bacteria recovered from diluted bull semen to 8 antibiotics (penicillin : PC, streptomycin : SM, chloramphenicol : CP, kanamycin : KM, tetracyclin : TC, erythromycin : EM, leucomycin : LM, oleandomycin : OM). A total of 274 strains of bacteria including 231 Gram negative ones (84.3%) and 43 Gram positive ones (15.7%) was used as materials. Of 274 strains of bacteria 191 were recovered from semens treated with PC and SM, and the remaining from those treated with no antibiotics. The sensitivity of the bacteria to the antibiotics was determined by the paper disk method and the degree of the sensitivity was expressed as shown in Table 1. The results obtained were as follows.
1) The greated part of 274 strains of bacteria was resistant to PC, EM, LM, and OM, the rate of the resistant bacteria being 7085% respectively (Fig. 1). About 50% of the bacteria were resistant to SM and CP. The rate of the bacteria resistant to KM and TC was lower (2534%).
2) Sensitivity of main species of Gram negative bacteria to the antibiotics was shown individually in Fig. 2. In Achromobacter and Alcaligenes, the greater part of strains was resistance to the antibiotics except KM and TC. In Pseudomonas almost all strains were resistant to them except SM. On the contrary, sensitivity of Gram positive bacteria to the antibiotics was relatively high as shown in Fig. 3.
3) In 191 strains of bacteria recovered from PC- and SM-treated semen, 104 (54.5%) were resistant doubly to PC and SM. But in the bacteria recovered from semen treated with no antibiotics, the rate of the doubly resistant ones was lower (31.4%) than in the former group (Table 2). The double resistant bacteria were much more in Gram negative group (47.2%) than in Gram positive group (9.9%) as shown in Table 3.
