Long-term carriage of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in the general population in the Netherlands

Abstract

Background

This longitudinal study aimed to investigate (risk factors for) persistence of carriage and molecular characteristics of extended-spectrum and pAmpC β-lactamase-producing (ESBL/pAmpC) Escherichia coli and Klebsiella pneumoniae (ESBL-E/K) in adults in the Dutch community.

Methods

Following a cross-sectional study (ESBL-E/K prevalence 4.5%), a subset of ESBL-E/K positive (n=76) and negative (n=249) individuals volunteered to provide five monthly faecal samples and questionnaires. ESBL-E/K was cultured using selective enrichment/culture and MLSTs were determined. ESBL/pAmpC-genes were analysed using PCR and sequencing. Plasmids were characterized and subtyped by plasmid MLST. Risk factors for persistent carriage were analysed using logistic regression.

Results

Of the initially ESBL-E/K positive participants, 25/76 (32.9%) remained positive in all subsequent samples; 51/76 persons (67.1%) tested ESBL-E/K negative at some time point during follow-up of which 31 (40.8%) stayed negative throughout the longitudinal study. Carriers often carried the same ESBL-gene and plasmid, but sometimes in different ESBL-E/K strains, indicative for horizontal transfer of plasmids. Of the 249 initially ESBL-E/K negative participants, the majority (n=218, 87.6%) tested negative during eight months follow-up, whereas 31/249 (12.4%) participants acquired an ESBL-E/K. E. coli phylogenetic group B2 and D and travel to ESBL high prevalence countries were associated with prolonged carriage.

Conclusion

ESBL-E/K carriage persisted for more than eight months in 32.9% of the initially ESBL-positive individuals, while 12.4% of initially negatives acquired ESBL-E/K during the study. A single positive test result provides no accurate prediction for prolonged carriage. Acquisition/loss of ESBL-E/K does not seem to be a random process, but differs between bacterial genotypes.