Outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit linked to artificial nails

Infect Control Hosp Epidemiol. 2004 Mar;25(3):210-5. doi: 10.1086/502380.


Background: From April to June 2001, an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae infections was investigated in our neonatal intensive care unit.

Methods: Cultures of the gastrointestinal tracts of patients, the hands of healthcare workers (HCWs), and the environment were performed to detect potential reservoirs for ESBL-producing K. pneumoniae. Strains of K. pneumoniae were typed by pulsed-field gel electrophoresis using XbaI. A case-control study was performed to determine risk factors for acquisition of the outbreak clone (clone A); cases were infants infected or colonized with clone A and controls (3 per case) were infants with negative surveillance cultures.

Results: During the study period, 19 case-infants, of whom 13 were detected by surveillance cultures, harbored clone A. The overall attack rate for the outbreak strain was 45%; 9 of 19 infants presented with invasive disease (n = 6) or developed invasive disease (n = 3) after colonization was detected. Clone A was found on the hands of 2 HCWs, 1 of whom wore artificial nails, and on the designated stethoscope of a case-infant. Multiple logistic regression analysis revealed that length of stay per day (odds ratio [OR], 1.05; 95% confidence interval [CI95], 1.02 to 1.09) and exposure to the HCW wearing artificial fingernails (OR, 7.87; CI95, 1.75 to 35.36) were associated with infection or colonization with clone A.

Conclusion: Short, well-groomed, natural nails should be mandatory for HCWs with direct patient contact

MeSH terms

  • Case-Control Studies
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • Cross Infection / transmission*
  • Disease Outbreaks* / prevention & control
  • Disease Reservoirs
  • Electrophoresis, Gel, Pulsed-Field
  • Female
  • Hand / microbiology
  • Humans
  • Infant, Newborn
  • Infection Control
  • Infectious Disease Transmission, Professional-to-Patient
  • Intensive Care Units, Neonatal*
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / prevention & control
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / isolation & purification*
  • Logistic Models
  • Male
  • Nails / microbiology*
  • New York City / epidemiology
  • Nursing Staff, Hospital
  • Risk Factors
  • beta-Lactamases / metabolism*


  • beta-Lactamases