Molecular Epidemiological Characteristics of bla IMP-4-Carrying Klebsiella pneumoniae ST-11 in Hospitalized Patients.

Purpose: To investigate the molecular epidemiology and risk factors of carbapenem-resistant Klebsiella pneumoniae (CRKP) infection.

Patients and methods: Patient's clinical data and CRKP strains were collected from November 2017 to December 2018 at a tertiary hospital in Wuhan, China. The antimicrobial susceptibilities, carbapenem-resistant genes, multi-locus sequence typing (MLST), homologous analysis, and risk factors for CRKP were determined.

Results: A total of 203 CRKP strains were isolated, and 98.5% (200/203) of patients were nosocomially infected. The mortality rate was 17.7% (36/203). All 203 strains were confirmed as carbapenemases -producing strains. The most predominant carbapenemase gene was bla _IMP-4 (81.3%, 165/203), followed by bla _KPC-2 (25.1%, 51/203) and bla _NDM-1 (23.2%, 47/205). Of the 203 strains, 28 (13.8%) had both bla _KPC-2 and bla _IMP-4 genes, 23 (11.3%) had both bla _IMP-4 and bla _NDM-1 genes, 20 (9.9%) had bla _KPC-2, bla _IMP-4 and bla _NDM-1 three genes. MLST analysis showed that there were 48 ST typologies (including 7 new STs), of which ST-11 was the most prevalent (59.6%, 121/203). Phylogenetic analysis showed that 203 CRKP isolates came from 7 clusters and exhibited a strong correlation with the isolation source. eBURST analyses indicated that CRKP isolates have undergone different evolutionary processes. Patients with ST-11 CRKP underwent more mechanical ventilation (50% vs 32.9%, P=0.020) and gastric catheterization (15.7% vs 6.1%, P=0.042) within 3 months before sample collection, and also had higher drug-resistance rate than non-ST-11 CRKP. Comparing with CSKP (carbapenem-sensitive Klebsiella pneumoniae), gastrointestinal disease (odds ratio [OR]=6.168, P=0.003), nosocomial infection (OR=5.573, P=0.012), antibiotic exposure (OR=4.131, P=0.004), urinary catheterization (OR=3.960, P=0.031) and venous/arterial catheterization (OR=2.738, P=0.026) within the preceding 3 months were independent risk factors for CRKP infection.

Conclusion: The IMP-4 was the most predominant carbapenemase and bla _IMP-4 bearing Klebsiella pneumoniae ST-11 was spreading in the hospital. Nosocomial infections, antibiotic exposure, and urinary and venous/arterial catheterization within 3 months were the risk factors for developing CRKP infection.