Use of yellow-pigmented enterococci as a specific indicator of human and nonhuman sources of faecal pollution

Abstract

Antibiotic susceptibility tests and restriction enzyme analysis (REA) of genomic DNA were performed to characterize the relationship between sources of isolates of yellow-pigmented enterococci. Antibiotic susceptibility tests were conducted with 10 therapeutic antibiotics and 54 isolates grouped by source (wild and other) depending on their origin. In three antibiotics, cephalothin, erythromycin, and vancomycin, there was a significant (p =< 0.05) association between susceptibility and source. Vancomycin resistance was significantly (p =< 0.001) higher in isolates from wild sources compared with that in isolates from other sources. The REA technique was performed on genomic DNA obtained from 17 Enterococcus mundtii isolates from: human (3), dog (4), horse (4), Canada goose (4), domestic goose (1), and Enterococcus mundtii ATCC 43186. A total of 12 different DNA types (A-L) were identified. Except for type D, 11 DNA types were unique and were distributed among dog (A, B, and C), human (E), horse (F, G, and H), Canada goose (I, J, and K), and domestic goose (L). Results suggested that vancomycin-susceptibility testing of yellow-pigmented enterococci may have potential value in the identification of sources of faecal pollution, especially when combined with traditional quantitative methods.Key words: yellow-pigmented enterococci, faecal pollution, antibiotic susceptibility, DNA typing.