Evaluation of the E-test (R) and ATB-pneumo (R) kit for the determination of MIC of betalactamines for streptococcus pneumoniae in daily practice

In 1999, during the survey of resistance of Streptococcus pneumoniae to ant ibiotics by 31 clinical laboratories of Rhone-Alpes area, MIC to penicillin (F), amoxicillin (AMX) and cefotaxime (CTX) of 877 PRP strains or with a d iameter of inhibition to oxacillin inferior to 26 mm, were determined by ea ch institution by E-test (n = 220 strains) or ATB-PNEUMO(R) (n = 657 strain s). MICs of these three antibiotics were determined by dilution in agar med ium by the coordinating center, The essential agreement was respectively fo r ATB-PNEUMO(R) andE-test((R)) 89% versus 84% for P (p > 0.05), of 86% vs 7 9% for AMX (p < 0.01), and of 91 % vs 86% for CTX (p = 0.03). When the stra ins were classified in clinical category, the differences were significant (p < 0.001) for AMX (85% vs 71 %) and for CTX (82% vs 75%) but not for P (7 3% vs 78%'). ATB-PNEUMO(R) method was more sensitive than E-test for the de tection of strains susceptible to P (90 vs 7391.), to AMX (83 vs 7811.) and to CTX (80 vs 72%) and for the,strains intermediate to AMX (90 vs 78%). On the contrary E-test is more specific than ATB-PNEUMO(R) for the detection of P-resistant strains (94 vs 86%). Finally, the specificity of both method s is the same for detection of P-S, AMX-R and CTX-I strains. (C) 2001 Editi ons scientifiques et medicales Elsevier SAS.