title: Evaluation of direct E-test on lower respiratory tract samples: a rapid and accurate procedure for antimicrobial susceptibility testing.
abstract: We compared the direct E-test susceptibility testing (DET) on respiratory samples with a standard microbroth dilution method (MBD) after quantitative cultures. A total of 152 samples from intensive care unit patients were processed by DET onto Mueller-Hinton agar. Oxacillin, piperacillin/tazobactam, cefepime, imipenem, ciprofloxacin, and amikacin were the antimicrobials evaluated. Cultures were 102 monomicrobials and 50 polymicrobials. Overall, 93.8% of the isolates were recovered by the DET. Among the 772 microorganism-antibiotic combinations evaluated, there was a total agreement with the MBD in 96.1%. There were 8 very major errors (1.03%), 15 major (1.94%), and 7 minor (0.91%). All discrepancies but one corresponded to polymicrobial cultures, and most occurred with cefepime (8 cases, 7.07%) and imipenem (7 cases, 6.18%). Readings of DET were easy to interpret and improved with transmitted light. DET on respiratory samples is a rapid technique that provides susceptibility results in 18 to 24 h comparable with these obtained by MBD.
authors: Servicio de Microbiología Clínica y Enfermedades Infecciosas, Hospital General Universitario Gregorio Marañón, 28007 Madrid, Spain. ecercenado@terra.es
authors: Emilia
authors: E
authors: Cercenado
authors: Sonia
authors: S
authors: Cercenado
authors: Mercedes
authors: M
authors: Marín
authors: María-Victoria
authors: MV
authors: Rico
authors: Teresa
authors: T
authors: Vicente
authors: Emilio
authors: E
authors: Bouza
mesh_terms: D015169:Colony Count, Microbial; D006801:Humans; D008168:Lung / Q000382:microbiology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D053717:Pneumonia, Ventilator-Associated / Q000382:microbiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*