Carbapenemase-producing bacteria isolates are increasingly identified throughout the world. Their early detection is becoming a major issue in the field of clinical microbiology in order to prevent their spread and preserve the efficacy of carbapenems which are becoming the antibiotics of last resort for treating severe infections. Moreover, carbapenemases are usually associated to many other non-beta-lactam resistant determinants giving rise to multidrug and pandrug resistance. Therefore, due to current population exchange and travel, early recognition of carbapenemase producers is becoming mandatory whatever the antibiotic policy or rate of multidrug-resistant nosocomial infections.
The vast majoriry of acquired carbapenemases belong to three of the four known classes of beta-lactamases, namely Ambler class A, Ambler class B (metallo-beta-lactamases (MBLs)) and Ambler class D (oxacillinases (OXAs)). These three classes of carbapenemases confer clinical resistance to carbapenems. Consequently, carbapenemase-producing bacteria isolates from these three classes have been involved in nosocomial outbreaks.
In particular, although OXA-48-like enzymes remain susceptible to extended-spectrum cephalosporins, they confer resistance to penicillins and reduced susceptibility to carbapenems, thereby making the clinical laboratory detection of OXA-48-like producing isolates difficult. In fact, it has been identified in multidrug-resistant isolates, which often accumulate multiple resistance mechanisms, including production of extended-spectrum beta-lactamases (ESBLs). Most carbapenemase producers co-express ESBLs, but several OXA-48- like producing isolates that do not carry ESBL genes may remain susceptible to extended-spectrum cephalosporins.
Thus, the present invention relates to a selective culture medium and a method for detecting carbapenem-resistant bacteria, in particular carbapenemase producers, in a test sample.
Scientific publication(s):
Diagn Microbiol Infect Dis, 2013 Feb, Girlich D. et al., Comparison of the SUPERCARBA, CHROMagar KPC, and Brilliance CRE screening media for detection of Enterobacteriaceae with reduced susceptibility to carbapenems, doi: 10.1016/j.diagmicrobio.2012.10.006
J Clin Microbiol., 2012 Aug, Nordmann P. et al., Detection of carbapenemase producers in Enterobacteriaceae by use of a novel screening medium, doi: 10.1128/JCM.06477-11