Performance of chromID ESBL, a chromogenic medium for detection of Enterobacteriaceae producing extended-spectrum β-lactamases

Abstract

The chromogenic agar medium chromID ESBL (bioMé rieux) was compared with BLSE agar medium (AES) for selective isolation and presumptive identification of extended-spectrum b-lactamase (ESBL)-producing Enterobacteriaceae from clinical samples. A total of 765 samples (468 rectal swabs, 255 urine samples and 42 pulmonary aspirations) obtained from 547 patients was processed. All bacterial strains isolated on either medium were further characterized using biochemical tests, and ESBL producers were confirmed by synergy testing. Genetic characterization of ESBL genes was determined by PCR. A total of 33 ESBL-producing Enterobacteriaceae strains [Escherichia coli (n516), Klebsiella pneumoniae (n58), Enterobacter spp. (n53), Citrobacter spp. (n55) and Proteus mirabilis (n51)] was recovered. The sensitivity after 24 h incubation was 88 % for chromID ESBL and 85 % for BLSE agar. At 48 h, the sensitivity of chromID ESBL increased to 94 % and was higher than that obtained with BLSE agar. The positive predictive value at 24 h for chromID ESBL was 38.7 % [95 % confidence interval (95 % CI) 28.3 -50.2 %)], which was significantly higher than that for BLSE agar [15.4 %, 95 % CI 10.1 -21.5 %]. On both media, false-positive results were mostly due to Pseudomonas aeruginosa and to Enterobacteriaceae overproducing chromosomal cephalosporinase (Enterobacter spp.) or a chromosomal penicillinase (Klebsiella oxytoca). This study showed that chromID ESBL, a ready-to-use chromogenic selective medium, is sensitive and specific for rapid, presumptive identification of ESBL-producing Enterobacteriaceae. Its chromogenic properties and its selectivity are particularly useful in specimens containing resident associated flora.

ESBL and AmpC beta-lactamase-producing Enterobacteriaceae in poultry in the Czech Republic

“…In the laboratory, the composite samples were mixed and inoculated onto chromID ESBL selective medium (bioMérieux), which can be characterized as chromogenic agar designed for the isolation and detection of ESBL-producing Enterobacteriaceae. On chromID ESBL, AmpC-positive Enterobacteriaceae can be also detected (Reglier-Poupet et al, 2008) The other samples were cloacal swabs taken from turkeys immediately after being killed at slaughterhouses in [2008][2009]. The turkeys were approximately 12 weeks old, weighed about 10-13 kg and were from three different farms.…”

How To Detect NDM-1 Producers

“…This culture medium may also provide a preliminary bacterial identification (E. coli; K. pneumoniae, etc.) at the species level based on the differential chromogenic properties of the enterobacterial species (13). Producers of IMP-, VIM-, and KPCtype carbapenemases with high-level resistance to cephalosporins and carbapenems were easily detected by ChromID ESBL (1,13).…”

“…at the species level based on the differential chromogenic properties of the enterobacterial species (13). Producers of IMP-, VIM-, and KPCtype carbapenemases with high-level resistance to cephalosporins and carbapenems were easily detected by ChromID ESBL (1,13). In this same study, we had evaluated another screening medium, CHROMagar KPC (CHROMagar Company, Paris, France), which contains a carbapenem as the selector for resistance and was first specifically designed for screening for KPC producers (1,14).…”

Screening haematology patients for carbapenem-resistant Klebsiella pneumoniae

“…Chromogenic agar has been described as a means of effectively and rapidly selecting out Extended Spectrum β-Lactamase (ESBL)-producing bacteria from other bowel organisms growing from clinical samples (Reglier-Poupet et al, 2008). By growing the K. pneumoniae on chromogenic agar in the presence of a 10 µg ertapenem antibiotic disc we are easily able to screen patients within 24 hours for K. pneumoniae which is resistant (i.e.…”