Abstract
Background Klebsiella pneumoniae is a human, animal, and environmental commensal and a leading cause of nosocomial infections, which are often caused by multiresistant strains. We evaluate putative sources of K. pneumoniae that are carried by and infect hospital patients.MethodsWe conducted a 6-month survey on 2 hematology wards at Addenbrooke’s Hospital, Cambridge, United Kingdom, in 2015 to isolate K. pneumoniae from stool, blood, and the environment. We conducted cross-sectional surveys of K. pneumoniae from 29 livestock farms, 97 meat products, the hospital sewer, and 20 municipal wastewater treatment plants in the East of England between 2014 and 2015. Isolates were sequenced and their genomes compared.Results Klebsiella pneumoniae was isolated from stool of 17/149 (11%) patients and 18/922 swabs of their environment, together with 1 bloodstream infection during the study and 4 others over a 24-month period. Each patient carried 1 or more lineages that was unique to them, but 2 broad environmental contamination events and patient–environment transmission were identified. Klebsiella pneumoniae was isolated from cattle, poultry, hospital sewage, and 12/20 wastewater treatment plants. There was low genetic relatedness between isolates from patients/their hospital environment vs isolates from elsewhere. Identical genes encoding cephalosporin resistance were carried by isolates from humans/environment and elsewhere but were carried on different plasmids.ConclusionWe identified no patient-to-patient transmission and no evidence for livestock as a source of K. pneumoniae infecting humans. However, our findings reaffirm the importance of the hospital environment as a source of K. pneumoniae associated with serious human infection.
Highlights
Klebsiella pneumoniae is a major cause of nosocomial infections worldwide, the public health importance of which has been amplified by the increasing prevalence of multidrug resistant K. pneumoniae carriage and infection [1,2,3]
Environmental sampling for K. pneumoniae was performed throughout the study, details of which are provided in Supplementary Material
K. pneumoniae was isolated from 23 stools from 17/149 (11%) patients, 3 of whom (2%) carried ESBL-producing K. pneumoniae, a similar rate to that reported previously [21]. 922 environmental swabs were taken from patient areas, medical equipment, and the wider environment over the 6-month study period
Summary
Klebsiella pneumoniae is a major cause of nosocomial infections worldwide, the public health importance of which has been amplified by the increasing prevalence of multidrug resistant K. pneumoniae carriage and infection [1,2,3]. Control of human K. pneumoniae infection requires an understanding of the potential sources from which infecting organisms are acquired. This is complex since K. pneumoniae can persist in a broad range of reservoirs including the hospital environment [4,5,6,7], retail meat [8, 9], livestock [10, 11] and wastewater [12, 13]. Previous genomic studies have largely focused on transmission in high-risk settings such as intensive care units. These have identified K. pneumoniae carriage as a significant risk factor for infection [14, 15]. A previous study identified limited within-host diversity in 20% of patients based on sequencing of up to three K. pneumoniae colonies from 40 patients [15]
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