Bracco Silvia, Migliavacca Roberta, Pini Beatrice, Corbo Nicoletta, Nucleo Elisabetta, Brigante Gioconda, Piazza Aurora, Micheletti Piero, Luzzaro Francesco
Laboratory of Microbiology, A. Manzoni Hospital, Lecco, Italy.
New Microbiol. 2013 Apr;36(2):181-6. Epub 2013 Mar 31.
The aim of this work was to evaluate the performance of the new chromogenic medium BrillianceTM CREAgar (Thermo Fisher Scientific) for determining the limit of detection of carbapenem-resistant enterobacteria (CRE). A total of 70 clinical isolates were studied. Of these, 30 were well-characterized CRE, including Klebsiella pneumoniae strains producing KPC-, VIM-, and OXA-type enzymes, VIM-positive Enterobacter cloacae and Escherichia coli, NDM-positive E. coli, and enterobacterial isolates characterized by porin loss associated with ESBL production or AmpC hyperproduction. Ten carbapenem-resistant non-fermentative isolates were also included as well as 30 carbapenem-susceptible isolates. Carbapenem-resistant strains were inoculated at three different concentrations onto Brilliance CRE Agar (from 1.5x101 CFU/ml up to 1.5x104 CFU/ml) whereas carbapenem-susceptible isolates were inoculated at a concentration of 1.5x102 CFU/ml. The medium sustained the growth of carbapenem-resistant isolates, showing detection limits from 1.5x101 CFU/ml (in 31/40 cases) to 1.5x104 CFU/ml. No growth was observed with carbapenem-sensitive control strains. Our results indicate that the Brilliance CRE Agar allows the growth of carbapenem-resistant isolates with low detection limits and could represent a useful screening medium for both enterobacteria and non-fermentative Gram-negative strains resistant to carbapenems.
本研究旨在评估新型显色培养基BrillianceTM CRE琼脂（赛默飞世尔科技公司）对耐碳青霉烯类肠杆菌（CRE）检测限的性能。共研究了70株临床分离株。其中，30株为特征明确的CRE，包括产KPC型、VIM型和OXA型酶的肺炎克雷伯菌菌株、VIM阳性的阴沟肠杆菌和大肠埃希菌、NDM阳性的大肠埃希菌，以及以与超广谱β-内酰胺酶（ESBL）产生或AmpC高产生相关的孔蛋白缺失为特征的肠杆菌分离株。还包括10株耐碳青霉烯类非发酵菌分离株以及30株对碳青霉烯类敏感的分离株。将耐碳青霉烯类菌株以三种不同浓度接种到Brilliance CRE琼脂上（从1.5×101 CFU/ml到1.5×104 CFU/ml），而对碳青霉烯类敏感的分离株以1.5×102 CFU/ml的浓度接种。该培养基支持耐碳青霉烯类分离株的生长，检测限为1.5×101 CFU/ml（31/40例）至1.5×104 CFU/ml。对碳青霉烯类敏感的对照菌株未观察到生长。我们的结果表明，Brilliance CRE琼脂能够支持低检测限的耐碳青霉烯类分离株生长，对于肠杆菌和耐碳青霉烯类革兰氏阴性非发酵菌可能是一种有用的筛选培养基。
