Assessment of Phenotypic Methods for Metalobetalactamase Detection in Clinical Isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa is considered one of the most important nosocomial pathogens. Its isolation is common in intensive care unit patients who also usually have multi-resistance. This greatly limits therapeutic options, since no effec tive drugs are available for treatment. The study aims to evaluate four phenotypic methods for detecting metallo-beta-lactamases. The double disc synergy with EDTA method, combined imipenem and meropenem disk with EDTA method, the E-Test-MBL method and the modified Hodge method, along with a reference method (PCR), are used to determine the phenotypic method or a combination of these is used that is more valid and safe for implementation in routine bacteriology laboratories. The sensitivity and specificity of the phenotypic methods used was good (over 90%); the modified Hodge test obtained the best results in detecting MBL-producing P. aeruginosa isolates (lower rate of false positive and negative). On analyzing the different combined methods for determining the association with greater sensitivity and specificity, the double disc method associated with the modified Hodge test met these characteristics. Results suggest that these two methods should be routinely used in a bacteriology laboratory, since they are easy to per form, sensi tive, specific and economical.