Nosocomial outbreak of gentamicin-resistant Klebsiella pneumoniae in a neonatal intensive care unit controlled by a change in antibiotic policy

Between August and November 1997, a nosocomial outbreak caused by gentamici n-resistant Klebsiella pneumoniae occurred in the Neonatal Intensive Care U nit (NICU) of our hospital. Thirteen neonates became colonized and three of them became infected. Comparison of the isolates by Amplified Fragment Len gth Polymorphism (AFLP) revealed clonal similarity for isolates of eight ne onates (homology > 90%). Cultures from environmental specimens were negativ e for gentamicin-resistant K. pneumoniae. A case-control study was conducte d to identify risk factors associated with acquistion of gentamicin-resista nt K. pneumoniae. Risk factors were low gestational age and birth weight. T hese neonates need more care and handling and may therefore, be more at ris k of colonization. Length of stay on the NICU was significantly longer for cases, but mean time until colonization (6.3 days) was shorter than the tot al stay for controls (9.5 days). No single member of the medical or nursing staff was significantly more involved with cases than with controls. The o utbreak was stopped by replacing gentamicin by amikacin as the antibiotic o f first choice whenever the use of an aminoglycoside antibiotic was indicat ed.