KAPALA MA, LAROCQUE C, SMALL GW, SKULNICK M, LOW DE, MCGEER A, WILLEY BM; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. D-183.

TML and Mount Sinai Hosp., Toronto, ON, Canada

BACKGROUND: Both Class A [A[R]] and Class C [C[R]] 3GC-R is increasing in EC and KS. Rapid, reliable and cost effective detection methods are essential. BDs automated susceptibility testing system, the Phoenix, using the NMIC/ID-5 panel (PH5) was compared to Viteks GNS-120 (V120) and GNS-606 (V606) cards to assess their 3GC-R detection capabilities. METHODS: 93 well characterized 3GC-R EC (63) and KS (25 K. pneumoniae, 5 K. oxytoca) were used as challenge organisms. Classification into A[R] (inhibitor-S, cefoxitin-S) and C[R] (inhibitor-R, cefoxitin-R) 3GC-R phenotypes was per NCCLS broth microdilution and disk diffusion (DD) confirmatory tests. These included MIC to cefpodoxime, ceftazidime, cefotaxime and aztreonam, +/- clavulanate, and cefoxitin. 3GC-R phenotypes in the 63 EC included 11 A[R], 45 C[R] and 7 A[R]+C[R]. In KS, the R-phenotypes were 16 A[R], 3 C[R], 8 A[R]+C[R] and 3 A-K1 (K. oxytoca). The PH-5, V120, V606 and a DD control were inoculated simultaneously from the same fresh culture. RESULTS: Overall, 3GC-R was detected in 87/93 strains (93.5%) by PH-5; 6 C[R] (5 EC, 1 KS) were missed. The V120 detected 61/93 (65.5%), of which 39/42 (93%) were A[R] strains; 31 C[R] (28 EC, 3 KS) and 1 A[R] EC were missed. The V606, detected via cepodoxime MIC, 86 (92.4%) of 3GC-R strains using the R-breakpoint of >4mg/L. The V606 failed to detect 7 strains: 1 A[R] EC, 2 C[R] EC, 3 A[R]+C[R] EC, and 1 A-K1. The V606s reliability improved to 97.8% when cefpodoxime MICs of 2 and 4mg/L were included as potentially 3GC-R. In such cases a confirmatory DD test was indicated. CONCLUSIONS: BDs PH-5 may be used for rapid and reliable detection of 3CG-R in EC and KS. The V606 proved a reliable screen for 3CG-R, especially when cefpodoxime breakpoints were lowered to >/=2 mg/L. The V120 detects A[R] reliably but frequently fails to detect C[R] phenotypes.

Publication Types:

• Meeting Abstracts

Keywords:

• Aztreonam
• Cefotaxime
• Cefoxitin
• Ceftazidime
• Cephalosporins
• Clavulanic Acid
• Escherichia coli
• Escherichia coli Infections
• Evaluation Studies
• Klebsiella
• Klebsiella Infections
• Microbial Sensitivity Tests
• methods

Other ID:

• GWAIDS0029425

UI: 102269057

From Meeting Abstracts