Risk factors for acquisition of CTX-M-15 extended-spectrum beta-lactamase-producing Klebsiella pneumoniae during an outbreak in a neonatal intensive care unit in Norway

Scand J Infect Dis. 2013 Jan;45(1):54-8. doi: 10.3109/00365548.2012.713116. Epub 2012 Sep 19.


Background: A CTX-M-15 extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae was responsible for an outbreak in the neonatal intensive care unit (NICU) at Stavanger University Hospital, Norway over a 5-month period (November 2008-April 2009). The risk factors for acquiring ESBL-producing K. pneumoniae during the outbreak were examined in this study.

Methods: Faecal or rectal cultures were obtained from infants hospitalized in the NICU during the outbreak period and examined for ESBL-producing K. pneumoniae. Data were retrospectively retrieved from the medical records, including sex, gestational age, birth weight, indwelling central vascular catheter, continuous positive airway pressure (CPAP), mechanical ventilation, parenteral nutrition, antibiotic treatment, mode of delivery (vaginal vs caesarean), length of hospital stay, and mortality.

Results: A total of 216 infants were hospitalized in the NICU during the outbreak period, of whom 212 were screened; 51 (24%) scored positive for faecal colonization with ESBL-producing K. pneumoniae. One infant acquired a clinical infection. Forty-four colonized infants and 55 non-colonized infants were included in the risk analysis. Colonized infants had a lower birth weight, lower gestational age, and a longer hospital stay compared to non-colonized infants. By logistic regression, prematurity (gestational age <37 weeks) and treatment with antibiotics were independent risk factors for acquiring ESBL-producing K. pneumoniae in the final model.

Conclusion: Prematurity and treatment with antibiotics were independent risk factors for colonization during this NICU outbreak with ESBL-producing K. pneumoniae.

MeSH terms

  • Carrier State / epidemiology
  • Carrier State / microbiology
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • Disease Outbreaks*
  • Female
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / epidemiology
  • Infant, Newborn, Diseases / microbiology*
  • Intensive Care Units, Neonatal / statistics & numerical data
  • Klebsiella Infections / epidemiology
  • Klebsiella Infections / microbiology*
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / isolation & purification*
  • Logistic Models
  • Male
  • Norway / epidemiology
  • Retrospective Studies
  • Risk Factors
  • Statistics, Nonparametric
  • beta-Lactam Resistance
  • beta-Lactamases / biosynthesis*


  • beta-lactamase CTX-M-15
  • beta-Lactamases