Duration of Colonisation With Extended-spectrum Beta-lactamase-producing Escherichia Coli: Results of an Open Cohort Study With Dutch Nursing Home Residents (2013 – 2019)

Abstract Background Escherichia coli sequence type ST131 is a recently emerged worldwide pandemic clonal group. Antibiotic resistance, virulence factors or colonisation fitness are mentioned among other as possible factors contributing to the worldwide success. In this study, we assessed the duration of rectal ESBL- producing E. coli colonisation in the residents, and compare duration of colonisation for ESBL-ST131 versus ESBL-non-ST131.MethodsRectal or faecal samples were obtained from residents of nursing home A between 2013 and 2019 and nursing home B between 2017 and 2019, with repeated point prevalence surveys at intervals of three to six months. Extended-spectrum β-lactamase (ESBL)-producing strains of E. coli were identified on selective culture and selective enrichment broth, and examined by antimicrobial susceptibility testing. In nursing home A multilocus sequence typing (MLST) and cluster analyse was performed by respectively O25:ST131-specific PCR and amplified fragment length polymorphism (AFLP). In nursing home B whole genome sequencing data were used to determine MLST and to perform a cluster analyse. Kaplan Meier survival analysis was performed to calculate the median time of rectal colonisation of ESBL-EC with a Log-Rank analysis to test for differences between ESBL-ST131 and ESBL-non-ST131.ResultsA total of 144 residents were included: 84 residents (58%) with ESBL-ST131 rectal colonisation and 60 residents (42%) with ESBL-non-ST131 rectal colonisation. Survival analysis showed a median colonisation length of 13 months for ESBL-ST131 (95%CI: 7,2 – 18,7) versus 8,3 months (95%CI: 2,8 – 13,8) for ESBL-non-ST131 (p = 0,028). Remarkably, in the subgroup ST131 the median colonisation length was significantly longer in female than in males: 25,7 months versus 8,1 months (p = 0,013).ConclusionHere we found a prolonged colonisation duration of ESBL-ST131 compared to ESBL-non-ST131 in residents of Dutch nursing homes. Prolonged colonisation duration complicates the controlling and ending an ESBL-ST131 outbreak, especially in long stay settings such as nursing homes.