Orally administered colistin leads to colistin-resistant intestinal flora and fails to prevent faecal colonisation with extended-spectrum β-lactamase-producing enterobacteria in hospitalised newborns

Volker Strenger (1) , Tanja Gschliesser (1) , Andrea Grisold (2) , Gernot Zarfel (2) , Gebhard Feierl (2) , Lilian Masoud (2) , Martin Hoenigl (3) , Bernhard Resch (1) , Wilhelm Müller (1) , Berndt Urlesberger (1)

1 Department of Paediatrics and Adolescent Medicine
2 Institute of Hygiene
3 Department of Medicine

Colonisation and infection with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) is an emerging problem. The aim of this study was to investigate whether colistin, which is reported to be effective against multiresistant enterobacteria, prevents ESBL-E colonisation in neonates. For prophylaxis of necrotizing enterocolitis, oral gentamicin (15mg/kg/day) is routinely used in all neonates hospitalised at the Neonatal Intensive Care Unit of University Hospital Graz (Austria). During the study period from May 2005 to September 2007, three ESBL-E outbreaks (total duration 18 months) occurred. During these outbreaks, gentamicin was immediately replaced by oral colistin (8mg/kg/day) in all hospitalised neonates. All neonates colonised with ESBL-E during the study period were retrospectively analysed with regard to the influence of colistin on ESBL-E colonisation. Genetic relatedness of isolates was assessed by repetitive sequence-based polymerase chain reaction (rep-PCR). During the study period, 30 (4.5%) of 667 neonates were colonised with ESBL-E. Twelve of twenty-one patients colonised with (ESBL-Kp) and one of nine patients colonised with (ESBL-Ko) had received oral colistin at time of colonisation with ESBL-E. Among ESBL-Kp, the rate of colistin resistance was significantly higher in the colistin group (=0.0075). Four different clones of ESBL-Kp and three different clones of ESBL-Ko were isolated, indicating the occurrence of patient-to-patient transmission. Colistin-resistant as well as colistin-susceptible isolates were detected within the same clones, indicating induction of resistance. At the dosage used, oral colistin did not prevent colonisation with ESBL-E and appeared to select colistin-resistant strains or to induce colistin resistance.

Mots clés: Extended-spectrum β-lactamase; ESBL; Neonatal Intensive Care Unit; Intestinal colonisation; Colistin; Selective digestive decolonisation

Volker Strenger, Tanja Gschliesser, Andrea Grisold, Gernot Zarfel, Gebhard Feierl, et al.. Orally administered colistin leads to colistin-resistant intestinal flora and fails to prevent faecal colonisation with extended-spectrum β-lactamase-producing enterobacteria in hospitalised newborns. International Journal of Antimicrobial Agents, 2010, 37 (1), pp.67. ⟨10.1016/j.ijantimicag.2010.09.010⟩. ⟨hal-00651645⟩