ISSN:
1435-4373
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The aim of the current five-center collaborative study was to reassess the interpretive criteria for cefaclor, loracarbef, cefprozil and cefixime previously adopted or proposed by the National Committee for Clinical Laboratory Standards (NCCLS) for disk diffusion susceptibility tests withHaemophilus influenzae on Haemophilus Test Medium (HTM) agar. MICs and zones of inhibition were determined using NCCLS methods, HTM and two collections of strains ofHaemophilus influenzae. One group of strains consisted of 118 stock organisms taken largely from various recent U.S. antibiotic resistance surveillance studies. The emphasis in this selected group of organisms was on strains that were beta-lactamase negative but ampicillin resistant (BLNAR) by some other mechanism. The second collection of test organisms consisted of 50 recent clinical isolates ofHaemophilus influenzae obtained from each of the five participating study centers. This group was considered representative of the type ofHaemophilus influenzae currently recovered from clinical sources in the USA. Frequency distribution assessment and error-rate bounded analysis of scattergram comparisons of MICs and zone sizes were used to develop the following zone diameters interpretive for disk diffusion susceptibility tests withHaemophilus influenzae on HTM agar: cefaclor, ≥20 mm (susceptible, S) and ≤16 mm (resistant, R); loracarbef, ≥19 mm (S) and ≤15 mm (R); and cefprozil, 〉18 mm (S) and 〈14 mm (R). The respective MIC correlates for all three antimicrobial agents were ≤8 µg/ml (S) and 32 µg/ml (R). For cefixime, a zone diameter size of ≥21 mm was recommended to define the susceptible category, with an MIC correlate of ≤1 µg/ml. Only a susceptible category was defined for cefixime testing. These new interpretive criteria have recently been adopted by the NCCLS.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01974638
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