Prevalence of Carbapenem-Resistant Bugs in Rectal Swabs from Patients/Working Staff in Medical Intensive Care Units

Introduction: With increased exposure to antibiotics, changes in the endogenous Microbiota due to constant pressure of antibiotic selection can happen silently, resulting in the culmination of multidrug resistant strains. As the normal microflora is commonly implicated in human infections, these resistant strains can lead to nosocomial infections or a limited outbreak. This study was undertaken to investigate the carriage of carbapenem-resistant isolates in the rectal swabs of patients admitted in Medical Intensive Care Units (MICU) of our hospital.

Methods: Between December 2016-February 2017, rectal swab samples from 178 patients and 31 staff members of MICU were collected, isolates identified and tested for carbapenemase activity. Patients who were detected with carbapenemase activity in rectal swabs were further analyzed for carbapenemase activity in clinical samples.The activity of isolates (if any) was co-related with the clinical samples in patients and real time PCR (Stratagene) was carried out for genotype analysis.

Results: Of the 209 strains obtained from rectal swabs, 29 (13.8%) isolates from patients and none from staff demonstrated carbapenemase activity. Thirteen out of these 29 patients were carriers and none of their clinical samples showed any growth. Twelve patients showed similarity i.e. rectal swabs and clinical samples showed similar type of Gram negative isolates with carbapenemase activity. No correlation was observed in 4 patients. (ie clinical sample and rectal swabs were different types). Real time PCR analysis for Klebsiella pneumonia carbapenemase (KPC) and New Delhi metallo-beta-lactamase 1(NDM) genes in ten patients showing similar isolates has shown that none of the isolates tested positive for KPC where as nine isolate pairs showed NDM gene expression indicating endogenous infections. (Two pairs were not revived after storage).

Conclusion: Screening for carriage of carbapenem resistant enteric Gram negative bacteria in patients undergoing elective or emergency gastrointestinal surgical procedures can guide clinicians about the antibiotic choices as these groups of patients are at high risk of possible endogenous infections.