Genome Sequencing Traces K pneumoniae Outbreak to Outpatient Clinic

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WGS is increasingly being used in clinical microbiology, especially to analyze nosocomial outbreaks as it provides multiple information levels from a single technique.
WGS is increasingly being used in clinical microbiology, especially to analyze nosocomial outbreaks as it provides multiple information levels from a single technique.

An investigation into an outbreak of New Delhi metallo-beta-lactamase (NDM)-producing Klebsiella pneumoniae across 2 Belgian hospitals identified an outpatient clinic as the likely common site of transfer and highlights the importance of infection control measures in outpatient settings. The results of the investigation were published in Clinical Infectious Diseases.

Investigators combined epidemiological data with whole-genome sequencing and pulse field gel electrophoresis characterization of 74 isolates of NMD-producing K pneumoniae. Isolates from the 2 outbreak hospitals located 50 miles apart totaled 9 for hospital A and 24 for hospital B, with the remaining 41 isolates coming from 15 other Belgian hospitals.

A ST716 clone of K pneumonia with a unique pulsotype was identified in 9/9 samples from hospital A and 20/24 from hospital B. These samples shared the unique pulsotype and were determined to be responsible for the outbreak. The outpatient clinic was identified as the bridging site after reviewing the epidemiological, phylogenetic, and resistome data. All but 1 strain from hospital A carried a Tn1331-like transposon, whereas no strains from hospital B did. The single case from hospital A that did not carry the transposon was referred to and treated in the outpatient clinic of hospital B the same day as the first K pneumonia-positive patient at hospital B, indicating that this patient was the source of transfer from hospital A to hospital B.

The transmission scenario based on the phylogenetic and molecular data proposed in this article cannot, however, be formally confirmed, as no screening policy was performed before the first case in hospital B was detected. Alternative sources of infection such as staff or patient visitors cannot be excluded as vectors of transmission. However, investigators believe that this type of multimodal analysis "enabled [them] to conclude that a multi-hospital outbreak of NDM-producing K. pneumoniae was most likely due to the same NDM-producing K. pneumoniae ST716 clone," and that the outpatient clinic was the likely transfer point.

The investigation also demonstrates "the importance of implementing adequate infection control measures in outpatient settings, especially as healthcare delivery moves from acute care facilities to outpatient clinics." Future work is still necessary to determine the importance of outpatient facilities in spreading multidrug-resistant organisms, along with possible control measures.

Reference

Heinrichs A, Argudín MA, De Mendonça R, et al. An outpatient clinic as a potential site of transmission for an outbreak of NDM-producing Klebsiella pneumoniae ST716: a study using whole-genome sequencing. [published online July 18 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy581

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