Artículo
Quality control for β-lactam susceptibility testing with a well-defined collection of Enterobacteriaceae and Pseudomonas aeruginosa strains in Spain
Autor/es | Cantón, Rafael
Loza, Elena Cornejo Gonzalo, María Carmen Baquero, Fernando Martínez Martínez, Luis |
Departamento | Universidad de Sevilla. Departamento de Microbiología |
Fecha de publicación | 2003 |
Fecha de depósito | 2017-07-27 |
Publicado en |
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Resumen | Eighteen Enterobacteriaceae and Pseudomonas aeruginosa strains, 16 of them with well-defined β-lactam re sistance mechanisms, were sent to 52 Spanish microbiology laboratories. Interpretative categories for 8 extended-spectrum ... Eighteen Enterobacteriaceae and Pseudomonas aeruginosa strains, 16 of them with well-defined β-lactam re sistance mechanisms, were sent to 52 Spanish microbiology laboratories. Interpretative categories for 8 extended-spectrum β-lactams were collected. Participating laboratories used their own routine susceptibility testing procedures (88% automatic systems, 10% disk diffusion, and 2% agar dilution). Control results were established by two independent reference laboratories by applying the NCCLS microdilution method and interpretative criteria. Interpretative discrepancies were observed in 16% of the results (4.4% for cefepime, 3.0% for aztreonam, 2.8% for piperacillin-tazobactam, 1.7% for cefotaxime [CTX] and ceftazidime, 1.1% for ceftriaxone, 0.9% for meropenem, and 0.3% for imipenem). High consistency with reference values (<5% of major plus very major errors) was observed with (i) American Type Culture Collection quality control strains; (ii) strains with low-efficiency mechanisms inactivating extended-spectrum β-lactams, such as OXA-1-producing Escherichiacoli or SHV-1-hyperproducing Klebsiella pneumoniae; (iii) strains with highly efficient mechanisms, such as SHV-5 porin-deficient K. pneumoniae, CTX-M-10 in Enterobacter cloacae hyperproducing AmpC, and P. aeruginosa with the MexAB OprM efflux phenotype or hyperproducing AmpC. Low consistency (>30% major plus very major errors) was detected in K1-producing Klebsiella oxytoca, CTX-M-9-producing E. coli, and in OprD- P. aeruginosa strains. Extended- spectrum β-lactamase (ESBL) -producing strains accounted for 86% of very major errors. Recognition of the ESBL phenotype was particularly low in Enterobacter cloacae strains (<35%), due to the lack of NCCLS-specific rules in this genus. A K1-producing K. oxytoca was misidentified by 10% of laboratories as an ESBL producer. The use of well-defined resistant strains is useful for improving proficiency in susceptibility testing in clinical laboratories. |
Cita | Cantón, R., Loza, E., Cornejo Gonzalo, M.C., Baquero, F. y Martínez Martínez, L. (2003). Quality control for β-lactam susceptibility testing with a well-defined collection of Enterobacteriaceae and Pseudomonas aeruginosa strains in Spain. Journal of Clinical Microbiology, 41 (5), 1912-1918. |
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