Phenotypic detection methods of metallo--lactamases -producing Pseudomonas aeruginosa strains isolated in urology ward from Skikda hospital Algeria

Acquired metallo-β-lactamases (MβL) are emerging determinants of resistance in Pseudomonas aeruginosa . The objectives of this study were to phenotypically detect MβL in P. aeruginosa collected in urology ward from Skikda hospital Algeria. A total of seventeen P. aeruginosa isolates were identified using API 20NE and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALD-TOFMS). Antibiotic susceptibility was performed using disk diffusion method on Muller-Hinton agar. The minimum inhibitory concentrations (MIC) of imipenem were determined by Etest method. Positively screened isolates were further subjected to four different methods phenotypic; Modified Hodge test (MHT), Imipenem-EDTA combined disk test (CDT), Imipenem-EDTA double-disk synergy test (DDST) and new biochemical method Modified Carba NP test (MCNP).  Out of 32 (45.71%) isolates were resistant to imipenem; 20 (62,5%) isolates were MβL producing, 5 (15.62%) were carbapenemase class A or D producing, and 7 (21.87%) isolates were detected as negative test. Rapid detection of MβL-producing P. aeruginosa may help inappropriate antimicrobial therapy and avoid the development and dissemination of these strains. Thus far, the validation of a simple and accurate MβL detection method such as CDT, DDST and MCNP test, can be easily incorporated into the daily routine of a clinical laboratory. Key words: Phenotypic detection, Pseudomonas aeruginosa, Metallo-β-lactamases.