We have evaluated the KOH test, the antibiotic disk test, and the Gram stain reaction for the preliminary grouping of gram-positive and gram-negative anaerobes. By the testing 326clinical isolates, 126 gram positive and 200 gram negative, with
the
KOH
test, vancomycin 5 ㎍ disk test and colistin 10㎍ disk test, we obtained the folowing parameters: sensitivity, 77 and 98%; specificity 100 and 96%; positive predictive value, 100 and94%; negative predictive value 73 and 98%; and efficiency, 86
and
97%
for the KOH test and the vancomycin test, respectively. the KOH reaction incorrectly grouped 28 of 43 Prevotella spp., 9 of 26 Fusobacterium spp., 6 of 6 Veillonella spp. And 3 of 3 Mobiluncus spp.. the vancomycin test correctly identified 42 of
46
gram-negative strains that had given a negative KOH reaction. As expected, the colistin susceptibility pattern was more variable with the gram-negative organisms than with the gram-positive organisms. In conclusion, the use of these preliminary
identification tests assist in the correct grouping of anaerobes.
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