Detection of Sex Pheromone Production in Isolates of Enterococcus faecalis that Increases Conjugation Frequency


Eight isolates of Enterococcus faecalis previously identified by API20 strep for Enterococci from diarrheal cases were used in the present study. Resistance towards ampicillin, cefalexin, tetracycline, chloramphenicol, gentamicin, erythromycin, streptomycin and nalidixic acid was determined and the results showed different antibiotic resistance pattern. The presence of a conjugation system in Enterococcus isolates was determined by mating with plasmid free strain of E.coli JM83, the results indicated the presence of conjugative system in isolates number 3,4,6 and 7 corresponded with the transfer of antibiotic resistance genes for cefalexin, tetracycline, gentamicin and nalidixic acid to recipient strain of E.coli JM83 at a frequency of (0.24 - 0.55×10-7) which may indicate the presence of an F plasmid in these isolates. The ability of the Enterococcus isolates to produce sex pheromone was detected by treating the conjugation mixture of the isolates 3,4,6 and 7 with E.coli JM83 with pheromones isolated from the isolates 1,2,5 and 8 separately. The results showed the ability of the pheromone isolated from isolate 2 to increase the conjugation frequency to (0.16×10-5) between isolate 6 and the recipient strain of E.coli JM83 which indicates the presence of a pheromone-responsive plasmid in the isolate 6 that is induced with the pheromone produced by isolate 2.