RESUMO
Introduction: Pseudomonas aeruginosa is a potent opportunistic nosocomial human pathogen among Gram-negative bacteria causing various life-threatening infections in patients from Intensive Care Units. This bacterium has become resistant to almost all commonly available antibiotics with limited treatment options. Multi drug resistant P. aeruginosa (MDRPA) is a major cause of concern among hospital acquired infections. It uses distinctive resistant mechanisms virtually to all the available antibiotics such as Metallo β-lactamases (MBL) production, extended spectrum β-lactamase production (ESBL), up regulation of effl ux systems related genes and decreased outer membrane permeability. This study was carried out to fi nd one the predominant resistance mechanisms among MDRPA and the prevalence of corresponding resistance genes. Materials and Methods: MDRPA isolates collected from various clinical samples for a period of 1-year (November 2009-Octo ber 2010) were included to detect the predominant mechanism of resistance using phenotypic and molecular methods. Molecular characterization of all these isolates was done by polymerase chain reaction (PCR) for the presence of blaVIM-2, blaIMP-1, blaOXA-23, and blaNDM-1 genes with specifi c primers. Results: Among 75 MDRPA isolates 84% (63) were MBL producers. Molecular characterization studied by PCR showed the presence of blaVIM-2 gene in 13% of MBL producers. Conclusion: The prevalence of MBLs has been increasing worldwide, particularly among P. aeruginosa, leading to severe limitations in the therapeutic options for the management. Thus, proper resistance screening measures and appropriate antibiotic policy can be strictly adopted by all the healthcare facility providers to overcome these superbugs.
RESUMO
A total of 66 Acinetobacter isolates obtained from JIPMER hospital wards were subjected to phenotypic identification schemes involving 25-test and a simplified 13-test panel of carbon utilization or assimilation tests. Reference strains belonging to different DNA groups (n=24) were also tested. Identification was done using numerical approach based on a matrix constructed of phenotypic data published elsewhere and the strains were assigned to different DNA groups according to classification of Tjernberg & Ursing. Sixty-six strains tested represented 10 DNA groups in matrix of large test panel; at a probability level of 0.95. Much simplified scheme of 13 assimilation test panel failed to differentiate some isolates with in A. calcoaceticus-A. baumannii complex (Acb-complex) unlike extended panel. In all, from the large panel 95% of isolates were identified correctly among all the isolates and it did not identify 5% of isolates. From the small panel, a total of 89% of isolates were identified correctly and it could not identify 11% of isolates. Reduced number of assimilation tests to 13 from the large panel bought reduction in identification percentage rate by only 6%. It is impossible for many bacterial diagnostic labs worldwide to perform large panel of carbon utilization tests in routine practice. Simplified panel of assimilation tests suggested here seems to be the best alternative method for identification of Acinetobacter species.