Klebsiella pneumoniae with extended spectrum beta-lactamase activity associated with a necrotizing enterocolitis outbreak

Background. Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in newborn infants, affecting primarily premature neonates. Clustering of cases in epidemics is well-described; many are associated with an identifiable pathogen. Patients and methods. Case reports are presented of six neonates seen with NEC during a 2-month period in 1998. All bacterial isolates were subjected to antibiotic testing, determination of MIC and molecular fingerprinting. Results. Klebsiella pneumoniae with extended spectrum beta-lactamase production was isolated from blood cultures of all six patients. In five patients the isolate appeared to be a single clone. The onset of NEC in the patients was earlier, more rapid and more severe than usual. Four of the six required surgery and five required mechanical ventilation. Two of the six patients died, but only one was directly related to a complication of NEC. All of the patients developed severe thrombocytopenia (platelet count <20 × 109/l), and three developed hepatitis. The K. pneumoniae proved difficult to eradicate. Extended courses of multiple antibiotics were administered and measures were introduced to reduce overcrowding and improve infection control. Conclusion. The isolation of a single clone of A. pneumoniae with extended spectrum of beta-lactamase activity during an NEC outbreak high-lights the need for strict infection control. This organism caused significant morbidity and was difficult to treat.