Napaporn Lertworapreecha, Kriengsak Poonsuk, and Thongchai Chalermchiakit

pp. 9 - 14

Abstract

Sixty strains of E. faecium were isolated from 30 samples of native chickens’ gastrointestinal tracts. All strains were
tested on acid and bile tolerance. Fifteen strains passed the acid tolerance test. The best five strains were EFMC 17, 21 and
24; EFMD 25; EFMI 47 and 49. Only four strains, EFMC 21; EFMD 30; EFMI 47, and 49, survived 4 hours of bile exposure.
Fifteen strains that passed the acid tolerance test were tested for their ability of intestinal mucus attachment. The results
indicated that all strains were able to attach to intestinal mucus. For the ability of pathogenic bacteria inhibition test, the
result found seven strains (EFMC 17, 21 and 24; EFMD 29 and 30; EFMI 46 and 49) showed better performance than strain
EFC. All seven strains were acid producer, but only four strains (EFMC 21; EFMD 25; EFMI 47 and 49) were able to release
bacteriocin. Based on proper probiotic properties two strains (EFMI 47 and 49) of E. faecium isolated from Thai native chicks
in this study have a potential use as probiotics. Antimicrobial susceptibility test of these two strains have been also performed;
they were susceptible to amoxicillin/clavulanic, ciprofloxacin, gentamycin, trimethoprime/sulphamethoxazole, vancomycin,
and trimethoprim. On the other hand, they were resistant to cefotaxime, erythromycin, and tetracycline. The DNA-DNA
hybridization percentage of DNA-DNA homology to E. faecium NRIC 1145 of EFMI 47 and EFMI 49 were 82.36 and 78.63%,
respectively.