Distribution of NDM1 Carbapenemase-Producing Strains on High-Risk Hospital Wards.

BACKGROUND

Carbapenem-resistant (CRP) is a group of multidrug-resistant (MDR) microorganisms that raise special treatment problems due to their intrinsic resistance to colistin. In this study, our aim is to provide a phenotypic and molecular characterization of the carbapenemases secreted by CRP strains isolated from inpatients from an intensive care unit (ICU) and surgical wards, as well as the identification of the risk factors involved in their acquisition.

METHODS

An observational, cross-sectional study was performed which included all strains isolated in samples from inpatients on high-risk wards of the largest university hospital in Western Romania, from July 2017 to April 2019. Meropenem-resistant strains (N=65) with MIC ≥16 µg/mL were subjected to a singleplex PCR assay for the detection of NDM, VIM and CTX-M genes. The analysis of risk factors was performed by logistic regression.

RESULTS

Out of 8317 samples that were processed, 400 strains were isolated: 64% belonging to the genus , 26.75% to the genus and 9.25% to the genus . Most CRP strains (N=56) were of MBL type, and 55 had the NDM gene as the prevalent gene substrate. was the main species that provided the circulating MDR strains. Most CRP strains came from patients admitted to ICU, being isolated mainly from bronchial aspirates and blood cultures. Multivariate analysis revealed 3 independent risk factors - mechanical ventilation>96h (HR: 40.51 [13.65-120.25], p <0.001), tracheostomy (HR: 2.65 [1.14-6.17], p = 0.024) and prolonged antibiotic therapy (HR: 1.01 [1.00-1.02], p = 0.03).

CONCLUSION

There is a significant increase in the incidence of CR strains, the MBL-NDM type being predominant. These strains presented various other resistance mechanisms, being often extremely difficult to treat and led to an excess of lethality of 27.16%.