<p>Rates of colonization with methicillin-resistant Staphylococcus aureus (MRSA) and/or vancomycin-resistant enterococci (VRE) were determined for 1320 infants within 7 days of neonatal intensive care unit discharge. Overall, 4% and 1% of the infants were colonized with MRSA or VRE, respectively. Predictors identified in fixed-effects models were surgery during hospitalization (for MRSA colonization) and prolonged antimicrobial treatment (for VRE colonization).</p>

<p>In multivariable analysis, prolonged antimicrobial treatment was a predictor of infant colonization with antimicrobial-resistant Gram-negative bacilli within 7 days of discharge from a neonatal intensive care unit.</p>

<p><strong>BACKGROUND: </strong>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.</p>

<p><strong>METHODS: </strong>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.</p>

<p><strong>RESULTS: </strong>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.</p>

<p><strong>CONCLUSIONS: </strong>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.</p>