Colonization with antimicrobial-resistant Gram-negative bacilli at neonatal intensive care unit discharge

Background. The epidemiology of the colonization of infants with antimicrobial-resistant Gram-negative bacilli (GNB) at discharge from the neonatal intensive care unit (NICU) is not well understood. Methods. A multicenter study in which rectal surveillance samples for culture were obtained at NICU discharge from infants hospitalized ≥ 14 days was performed. Factors associated with colonization with GNB resistant to gentamicin, third/fourth-generation cephalosporin agents, or carbapenem agents were assessed by using a fixed-effects model. Results. Of these infants, 9% (119 of 1320) were colonized with ≥ 1 antimicrobial-resistant GNB. Prolonged treatment (≥ 10 days) with meropenem or third/fourth-generation cephalosporin agents or treatment for ≥5 days with a β-lactam/β-lactamase combination agent were associated with an increased risk of colonization with GNB resistant to gentamicin. Surgery and ≥ 5 days of treatment with third/fourth-generation cephalosporin agents, a β-lactam/β-lactamase combination agent, or metronidazole were associated with an increased risk of colonization with GNB resistant to third/fourth-generation cephalosporin agents. Female sex and prolonged treatment (≥ 10 days) with meropenem were associated with colonization with GNB resistant to carbapenem agents. Conclusions. Prolonged treatment with broad-spectrum antibiotics was associated with the colonization of infants with antimicrobial- resistant GNB within 7 days of NICU discharge. These findings suggest the potential for dissemination of resistant GNB from colonized infants to other NICUs, the community, or pediatric long-term care facilities. Antimicrobial stewardship efforts aimed at improving appropriate antibiotic use could have a beneficial effect on the emergence of antimicrobial-resistant GNB in the NICU population.