Prevalence of Acinetobacter baumannii and Pseudomonas aeruginosa isolates resistant to imipenem by production of metallo-β-lactamase

Metallo-beta-lactamases (MBL) are enzymes produced by Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter baumannii. These enzymes make these isolates resistant to imipenem. Aim. - The aim of this study was to determine the prevalence of this resistance mechanism in Pseudomonas aeruginosa and Acinetobacter baumannii strains identified in the bacteriology laboratory of the Rabat Ibn Sina teaching hospital, Morocco. Materials and method. - Screening for MBL was systematic in all resistant strains and/or strains with decreased sensitivity to imipenem, according to Dongeun Yong et al.'s method, using a sterilized solution of EDTA 0.5 M pH 8. Results. - Eighty-five bacterial strains (48 P. aeruginosa and 37 A. baumannii) were identified 23% (11) and 57% (21) of which were respectively resistant to the imipenem. The prevalence of MPL producing strains was 27% for P aeruginosa and 38% for A. baumannii. Conclusion. - These results show that the frequency of these strains is increases in our hospital and that their emergence represents a serious therapeutic and epidemiological problem. This means that we need to implement the super-vision of hospital microbial environment and strictly apply hygiene measures. (C) 2006 Elsevier SAS.