The Bacterial Colonization with Extended Spectrum beta -Lactamase- and Metallo- beta -Lactamase Producing Gram-Negative Bacteria at Intensive Care Unit Patients

Metallo- beta-Lactamase (MBL) and Extended spectrum beta-Lactamase (ESBL) have been increasingly emerging as pathogens involved in serious nosocomial infection. ESBL producing strains colonize critically ill patients who serve as a reservoir for epidemic outbreak. The aim of this study was to detect the rate of colonization by ESBL and MBL producing Gram negative bacteria in ICU patients on admission. The study was conducted on 87 patients on admission to ICU; nasal, oral and rectal swabs were taken from each patient. Bacterial culture and strain identification were carried out using Standard microbiological methods, as well as antibiotic susceptibility test using the disc diffusion method. Gram negative isolates were tested for ESBL and MBL production by disc diffusion, double disc synergy test and E-test. PCR was done for MBL phenotypes. Evaluation of some risk factors for colonization includes: age, hospitalization before ICU admission, antibiotics intake and usage of ventilator. The study revealed that 46 (52.9%) out of overall 87 studied patients were colonized by Gram negative bacteria, ESBL production was detected in 43/46 (93.4%), the commonest of which was E. coli 22/46 (47.8%), MBL production was detected in 37/46 (80.4%) of them, the commonest of which was Psudomonas aeruginosa 16/46 (34.8%). The blaIMP was the commonest gene detected among MBL phenotype, it was detected in 48(45.7%) of overall 105 isolates, while blaGIM was the lowest genotype, it was detected only in 3/105 (2.9%) isolates. The study revealed that: age, hospitalization, antibiotic intake, use of mechanical ventilator is all risk factors for colonization by MBL and ESBL producing bacteria in ICU patients. We concluded that most critically ill patients may be colonized by ESBL and MBL producing Gram negative bacteria, therefore ICU patients must be examined for it, to be treated properly to avoid occurrence and spread of infection in ICU.