Risk Factors, Temporal Dependence, and Seasonality of Human Extended-Spectrum β-Lactamases-Producing Escherichia coli and Klebsiella pneumoniae Colonization in Malawi: A Longitudinal Model-Based Approach.

Background: Sub-Saharan Africa has the highest estimated death rate attributable to antimicrobial resistance, especially from extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E). However, the dynamics of human colonization in the community with ESBL-E are not well described. Inadequate water, sanitation, and hygiene infrastructure and associated behaviors are believed to play an important role in transmission of ESBL-E, and an improved understanding of the temporal dynamics of within-household transmission could help inform the design of future policies.

Methods: In this 18-month study, using microbiological data and household surveys, we built a multivariable hierarchical harmonic logistic regression model to identify risk factors for colonization with ESBL-producing Escherichia coli and Klebsiella pneumoniae, reflecting household structure and temporal correlation of colonization status.

Results: Being male was associated with a lower risk of colonization with ESBL-producing E. coli (odds ratio [OR], 0.786; credible interval [CrI], .678-.910), whereas the use of a tube well or a borehole was associated with an increased risk (OR, 1.550; CrI, 1.003-2.394). For ESBL-producing K. pneumoniae, recent antibiotic exposure increased risk of colonization (OR, 1.281; CrI, 1.049-1.565), whereas sharing plates decreased that risk (OR, 0.672; CrI, .460-.980). Finally, the temporal correlation range of 8 to 11 weeks provided evidence that within-household transmission occurs within this time frame.

Conclusions: We describe different risks for colonization with different enteric bacterial species. Our findings suggest interventions to reduce transmission targeted at the household level need to focus on improving water, sanitation, and hygiene infrastructure and associated behaviors, whereas at the community level, they should focus on both environmental hygiene and antibiotic stewardship.