Gabriele Bianco1, Marco Iannaccone2, Matteo Boattini1, Rossana Cavallo1, Cristina Costa1. 1. Microbiology and Virology Unit, University Hospital Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy. 2. Microbiology and Virology Unit, University Hospital Città della Salute e della Scienza di Torino, Corso Bramante 88, 10126, Turin, Italy. marco.iannaccone@unito.it.
Abstract
INTRODUCTION: Early and appropriated antimicrobial therapy showed to positively impact on the clinical improvement of septic patients. The aim of this study was to evaluate E-test methodology to obtain rapid results of antimicrobial susceptibility, starting directly from blood culture bottles positive to Gram-negative monomicrobial flora. MATERIALS AND METHODS: One hundred and five blood culture samples positive to Gram-negative rods at the microscopic examination were collected. Bacterial identification from early subculture on blood agar after 4 h incubation and rapid direct E-test from blood culture broth were performed on every sample. Antibiotics MIC were achieved after 5-6 h of incubation. Resulting MIC values were compared with those obtained with reference E-test from the overnight subculture. Categorical agreement (CA) and essential agreement (EA) were evaluated. RESULTS: Comparison between rapid direct E-test and reference E-test showed CA ranging from 95.1 to 100 % and 88.2 to 100 % for Enterobacteriaceae (EB) and for non-fermenting Gram-negative bacilli, respectively. Rapid direct E-test showed an overall EA of 80.1 %, revealing different EA rates for the tested antibiotics. Among carbapenemase-producing EB, CA of 87.5 % and EA of 75.5 % for MP were achieved. DISCUSSION: The same-day communication of the antimicrobial susceptibility represents an important challenge in the multidrug-resistance era. Despite not being able to anticipate actual MIC values, the rapid direct E-test may be useful to obtain preliminary AST results in 5-6 h, especially if used in association with phenotypic or genotypic tests to identify the main resistance mechanisms.
INTRODUCTION: Early and appropriated antimicrobial therapy showed to positively impact on the clinical improvement of septic patients. The aim of this study was to evaluate E-test methodology to obtain rapid results of antimicrobial susceptibility, starting directly from blood culture bottles positive to Gram-negative monomicrobial flora. MATERIALS AND METHODS: One hundred and five blood culture samples positive to Gram-negative rods at the microscopic examination were collected. Bacterial identification from early subculture on blood agar after 4 h incubation and rapid direct E-test from blood culture broth were performed on every sample. Antibiotics MIC were achieved after 5-6 h of incubation. Resulting MIC values were compared with those obtained with reference E-test from the overnight subculture. Categorical agreement (CA) and essential agreement (EA) were evaluated. RESULTS: Comparison between rapid direct E-test and reference E-test showed CA ranging from 95.1 to 100 % and 88.2 to 100 % for Enterobacteriaceae (EB) and for non-fermenting Gram-negative bacilli, respectively. Rapid direct E-test showed an overall EA of 80.1 %, revealing different EA rates for the tested antibiotics. Among carbapenemase-producing EB, CA of 87.5 % and EA of 75.5 % for MP were achieved. DISCUSSION: The same-day communication of the antimicrobial susceptibility represents an important challenge in the multidrug-resistance era. Despite not being able to anticipate actual MIC values, the rapid direct E-test may be useful to obtain preliminary AST results in 5-6 h, especially if used in association with phenotypic or genotypic tests to identify the main resistance mechanisms.
Authors: Wouter van den Bijllaardt; Anton G Buiting; Johan W Mouton; Anouk E Muller Journal: Int J Antimicrob Agents Date: 2017-03-03 Impact factor: 5.283
Authors: J Rello; T S R van Engelen; E Alp; T Calandra; V Cattoir; W V Kern; M G Netea; S Nseir; S M Opal; F L van de Veerdonk; M H Wilcox; W J Wiersinga Journal: Clin Microbiol Infect Date: 2018-03-24 Impact factor: 8.067
Authors: Richard E Nelson; Rachel B Slayton; Vanessa W Stevens; Makoto M Jones; Karim Khader; Michael A Rubin; John A Jernigan; Matthew H Samore Journal: Infect Control Hosp Epidemiol Date: 2017-06-01 Impact factor: 3.254