ABSTRACT
There is no consensus on optimal screening procedures for multidrug-resistant Enterobacteriaceae (MDRE) in intensive care units (ICUs). Therefore, we assessed five strategies for the detection of extended-spectrum beta-lactamase (ESBL) and high-level expressed AmpC cephalosporinase (HL-CASE) producers. During a 3-month period, a rectal screening swab sample was collected daily from every ICU patient, from the first 24 h to the last day of ICU stay. Samples were plated on MDRE-selective media. Bacteria were identified using MALDI-TOF mass spectrometry and antibiograms were performed using disk diffusion. MDREs were isolated from 682/2348 (29.0%) screening samples collected from 93/269 (34.6%) patients. Incidences of patients with ESBL and HL-CASE producers were 17.8 and 19.3 per 100 admissions, respectively. In 48/93 patients, MDRE carriage was intermittent. Compared with systematic screening at admission, systematic screening at discharge did not significantly increase the rate of MDRE detection among the 93 patients (62% vs. 70%). In contrast, screening at admission and discharge, screening at admission and weekly thereafter, and screening at admission and weekly thereafter and at discharge significantly increased MDRE detection (77%, p 0.02; 76%, p 0.01; 86%, p<0.001, respectively). The difference in MDRE detection between these strategies relies essentially on the levels of detection of patients with HL-CASE producers. The most reasonable strategy would be to collect two samples, one at admission and one at discharge, which would detect 87.5% of the ESBL strains, 67.3% of the HL-CASE strains and 77.4% of all MDRE strains. This study should facilitate decision-making concerning the most suitable screening policy for MDRE detection in a given ICU setting.
Subject(s)
Anti-Bacterial Agents/pharmacology , Carrier State/diagnosis , Cephalosporins/pharmacology , Enterobacteriaceae Infections/diagnosis , Enterobacteriaceae/isolation & purification , Infection Control/methods , Intensive Care Units , Adult , Aged , Aged, 80 and over , Bacteriological Techniques , Carrier State/microbiology , Critical Care/methods , Enterobacteriaceae/drug effects , Enterobacteriaceae Infections/microbiology , Female , Humans , Male , Mass Screening/methods , Microbial Sensitivity Tests , Middle Aged , Rectum/microbiology , Retrospective Studies , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , beta-Lactam ResistanceABSTRACT
Overall, 2,337 rectal screening samples (RSSs) were seeded by using the Wasp instrument for automated microbiological processing with five media for detection of extended-spectrum ß-lactamase (ESBL): CHROMagar, ChromID, Brilliance, BD Drigalski, and HEGP media. Of 354 RSSs harboring ESBL-producing isolates, 89.3% were found to be positive on all media. Sensitivity and specificity ranged from 95.5 to 98.3% and from 57.9 to 72.3%, respectively. No medium was perfectly ESBL selective, and non-ESBL-producing strains were mainly Enterobacteriaceae overproducing AmpC ß-lactamase and nonfermenting Gram-negative bacilli, mostly Pseudomonas aeruginosa.
