Long-term Carriage of Extended-Spectrum ß-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae in the General Population in The Netherlands.

Background. This longitudinal study aimed to investigate (risk factors for) persistence of carriage and molecular characteristics of extended-spectrum and plasmid-encoded AmpC 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 5 monthly fecal samples and questionnaires. ESBL-E/K was cultured using selective enrichment/ culture and multilocus sequence types (MLSTs) were determined. ESBL/pAmpC-genes were analyzed using polymerase chain reaction (PCR) and sequencing. Plasmids were characterized and subtyped by plasmid MLST. Risk factors for persistent carriage were analyzed using logistic regression. Results. Of the initially ESBL-E/K–positive participants, 25 of 76 (32.9%) remained positive in all subsequent samples; 51 of 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 8 months of follow-up, whereas 31 of 249 (12.4%) participants acquired an ESBL-E/K. Escherichia coli phylogenetic group B2 and D and travel to ESBL high-prevalence countries were associated with prolonged carriage. Conclusions. ESBL-E/K carriage persisted for >8 months in 32.9% of the initially ESBL-positive individuals, while 12.4% of initially negative individuals 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. [ABSTRACT FROM AUTHOR]