836 - Complete genome sequencing reveals a melting pot of diverse Klebsiella pneumoniae pathogens in two Detroit hospitals

Background: Klebsiella pneumoniae is one of the leading causes of healthcare-associated infections. Treatment of Klebsiella pneumonia is difficult due to the antibiotic resistance and high survival on environmental surfaces. Whole genome sequencing analysis of Klebsiella pneumoniae clinical isolates were performed to study the transmission of Klebsiella pneumonia in hospital settings.Figure 1. Minimum spanning tree (MST) of wgMLST profiles of Klebsiella pneumoniae sequence types found in the two hospitals. Branch lengths reflect the number of allele differences between the isolates in the connected nodes
Figure 2. Minimum spanning tree (MST) of wgMLST profiles of Klebsiella pneumoniae isolates. Node labels indicate patients’ hospital unit.


Methods: Clinical bacterial isolates from patients admitted to two disparate, geographically distinct tertiary care hospitals (H1, H2) in Detroit, Michigan, after 48 hours of admission from 2017- 2019 were collected and sequenced. Whole genome multilocus sequence typing (wgMLST) analysis was performed using Illumina NextSeq platform. De novo assembly of the contigs was performed using SPAdes assembler. WgMLST (assembly-free and assembly-based calls) was performed using calculation engine on the Bionumerics v7.6 platform. Minimum spanning tree with the isolates was constructed and arranged by their MLST Pasteur serotype and hospital/ward of the patient isolate collection.

Results: Total 17 different MLST Pasteur serotypes were observed from WgMLST analyzation of forty-five Klebsiella pneumoniae clinical patient isolates. All the Klebsiella pneumoniae isolates of HAI obtained from two hospitals were genetically distinct. As shown in Figure 1, there were three distinct clusters on the minimum spanning tree. Out of 17 STs, 4 were present in both hospitals. Though there was no predominant ST type, ST15 and ST11 were the most frequent isotypes (18% each). Both ST15 and ST11 were evenly spread across both hospitals, but the pattern was different. While ST15 was predominantly found in two units (H1U3 and H2U4), ST11 was found in multiple units. ST348 and ST29 were predominantly found in H1, whereas ST16 was found in H2.

Conclusion: Majority of Klebsiella pneumoniae infection is sporadic and there was no evidence of hospital spread. The WgMLST analysis showed the isolates distributed across the phylogeny of Klebsiella with diverse serotypes from the three main diverse evolutionary origin. Our study showed that the global spread of various serotypes of Klebsiella pneumoniae has already reached a significant level in these two Detroit hospitals possibly the catchment area.