ANTIBIOTIC-RESISTANCE AMONG ENTEROCOCCAL ISOLATES FROM ENVIRONMENTAL AND CLINICAL SOURCES

Antibiotic resistance among enterococci and fecal streptococci was examined by testing 149 isolates from pork, water, and clinical material, as well as 50 strains of 13 known species, for resistance to 27 different antimicrobial agents. Tests were performed by using the MicroScan Pos MIC type 6 panels. Pork isolates exhibited less resistance than either water or clinical isolates to most antibiotics, although a larger proportion of pork isolates than others was resistant to tetracycline. Comparisons of antimicrobial-resistance patterns between enterococcal species revealed that Enterococcus faecium was most resistant to beta-lactam antimicrobials, especially ampicillin, whereas Enterococcus faecalis seemed to be the most resistant to the synergistic effects of antimicrobial combinations. Vancomycin resistance was observed in one Enterococcus hirae isolate from water. Enterococcal isolates from any of the sources tested did not show multiple resistance to antibiotics (such as gentamicin, ampicillin, streptomycin, and vancomycin) used to treat serious infections caused by gram-positive cocci.