Phenotypic and Genotypic Characterisation of Carbapenem-Resistant Enterobacterales Isolated from Intensive Care Unit Specimens: A Cross-Sectional Study at a Tertiary Care Hospital
DOI:
https://doi.org/10.48047/jadf7k91Keywords:
Carbapenem-resistant Enterobacterales, arbapenemase, antimicrobial resistance, ceftazidime-avibactamAbstract
Background: Carbapenem-resistant Enterobacterales (CRE) have become important priority pathogens in the intensive care units (ICUs) worldwide. The ICMR Antimicrobial Resistance Surveillance Network (AMRSN) 2022 provided data on meropenem resistance in clinical Klebsiella pneumoniae isolates in India, which is around 56%, and there is an urgent need for epidemiological data based on the institution. Knowing the local prevalence of CRE, distribution of the carbapenemase genes, the antibiogram profile and risk factors for CRE acquisition is of key importance for developing effective antimicrobial stewardship and infection control measures.
Design: This observational cross sectional study was carried out for 18 months in the ICU of tertiary care hospital. All Enterobacterales isolates from clinical samples (blood, urine, respiratory sample, pus, body fluid) of patients on the inpatient wards in the ICU were considered (target n = 420). VITEK-2 automated system and disc diffusion CLSI M100-2024 breakpoints were used to detect carbapenem resistance; and the modified carbapenem inactivation method (mCIM) and EDTA-mCIM were used to confirm the resistance phenotype. Carbapenemase-encoding genes (blaNDM, blaOXA-48-like, blaKPC, blaVIM, blaIMP) were characterised by multiplex real-time PCR. Independent predictors of CRE acquisition were identified using multivariable logistic regression.
Results: CRE prevalence was 33.1% (n = 139/420). The most common organisms were Klebsiella pneumoniae (40.3%), Escherichia coli (28.1%) and Enterobacter spp. (18.7%). The blaNDM gene was identified in 55.4% of CRE isolates, blaOXA-48-like in 25.2% and both carbapenemases in 12.2%. 88.5% of CRE isolates were colistin susceptible, and 62.2% of them were ceftazidime-avibactam susceptible (significantly less among blaNDM producers, p < 0.001). Independent predictors of CRE acquisition were prior carbapenem use (adjusted OR 4.1; 95% CI 2.3–7.2), ICU stay >7 days (aOR 3.2; 95% CI 1.9–5.4), and mechanical ventilation (aOR 2.6; 95% CI 1.5–4.6).
NDM was the most common carbapenemase and the prevalence of CRE in the ICU was significant. Ceftazidime-avibactam was still active, particularly against the NDM producers. Active surveillance, contact precaution bundles and antimicrobial stewardship are all needed now. The results correlate with the national AMRSN standards and highlight the importance of prompt genotypic characterisation for prompt salvage therapy
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