Comparison of inoculation methods for testing enterococci by using vancomycin screening agar

Abstract

One hundred four recent clinical isolates of Enterococcus species were screened for vancomycin resistance by using inocula of 105 or 106 CFU dispensed by pipet and by use of a cotton swab dipped in a 0.5 McFarland standard organism suspension applied to the surface of brain heart infusion agar containing 6 μg of vancomycin per ml. The three inoculation methods were equivalent in the detection of nonsusceptible isolates. The use of swab inoculation was convenient and less costly than the use of micropipets.