Molecular Characterization of New Delhi Metallo-ß-Lactamases-Producing Bacteria in the Gastrointestinal Tract of Intensive Care Unit Patients

Background: The emergence of carbapenem-resistance in the gut flora of patients in the intensive care unit (ICU) poses a significant risk for infection with these types of pathogens. Materials and methods: New Delhi metallo-ß-lactamase 1 (NDM-1) in the gut flora of ICU patients was detected in cultures of a single rectal swab from each patient admitted to the ICU for a minimum period of 48 hrs. Samples were processed in the microbiology laboratory using blood agar and MacConkey agar. Identification of pathogens, carbapenem resistance, and metallo-ß-lactamase production was made using standard laboratory procedures. Bacterial isolates were also used for the determination of the NDM-1 gene by molecular methods. Results: One hundred twenty-two patients with different clinical presentations were recruited in the study. Two hundred nine bacteria were isolated, with Escherichia coli being the most common isolate. A total of 54/122 (44.3%) patients harbored carbapenem-resistant organisms (CRO), 36/122 (29.5%) carried metallo-β-lactamase-producing organisms (MBLO), and 30/122 (24.6%) carried bacteria with the NDM-1 gene. Patients who harbored CRO and MBLO had longer mean duration of stay in the ICU and hospital than those not harboring CRO and MBLO. All the metallo-β-lactamases were simultaneously resistant to other groups of antibiotics also. Use of invasive devices, three or more classes of antibiotics, hospitalization during the previous six months, comorbidities, and hospital stay for ≥48 hours before ICU admission had a significant association with colonization with CRO. Conclusion: Patients admitted in ICU or with serious diseases should be screened for gastrointestinal carriage of carbapenem-resistant organisms. Irrational use of antibiotics must be stopped to prevent the emergence and spread of such organisms.