Table 3 Methodological heterogeneities in previous studies and open questions for future decolonization studies

Methodological heterogeneities in previous studies

▪ Different ESBL-E sampling (perianal vs. rectal swab vs. fecal sample) and detection (culture vs. PCR-based technology vs. combined)

▪ Diverse definitions of decolonization success (number of negative samples, duration of follow-up period)

▪ In- or exclusion of patients with concomitant ESBL-E infection

▪ Intestinal decolonization with or without systemic antibiotic treatment

▪ Availability of pre-decolonization antibiotic susceptibility tests and variable impact on decolonization regimen

Open questions that need to be addressed in future studies

▪ Are there effective decolonization strategies leading to sustained clearance of ESBL-E?

▪ What is the optimal regimen (combination regimen?), dose and duration?

▪ Will we observe resistance development (and risk to lose important last resort antibiotics e.g. colistin)?

▪ Which patients may have the greatest benefit of decolonization?

▪ What is the impact of extraintestinal colonization (perianal region, groin)? Should decolonization strategies address this?

▪ Does relapse represent intestinal ‘outgrowth’ of suppressed ESBL-E or re-colonization from extraintestinal sites or other patients, food sources or the environment?

▪ Do pathogens differ with respect to the decolonization success rate (e.g. Klebsiella spp. vs. Escherichia coli vs. Enterobacter spp.)?

▪ How robust is the intestinal microbiome under antibiotic treatment? What is its impact on ESBL-E colonization resistance?