A prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: Did staff fingernails play a role in disease transmission?

OBJECTIVES: To describe an outbreak of Pseudomonas aeruginosa bloodstream i nfection (BSI) and endotracheal tube (EET) colonization in a neonatal inten sive care unit (NICU), determine risk factors for infection, and make preve ntive recommendations. DESIGN: A 15-month cohort study followed by a case-control study with an en vironmental survey and molecular typing of available isolates using pulsed- field gel electrophoresis. SETTING AND PATIENTS: Neonates in the NICU of a university-affiliated child ren's hospital. INTERVENTIONS: Improved hand washing and restriction of use of long or arti ficial fingernails. RESULTS: Of 439 neonates admitted during the study period, 46 (10.5%) acqui red P aeruginosa; 16 (35%) of those died. Fifteen (75%) of 20 patients for whom isolates were genotyped had genotype A, and 3 (15%) had genotype B. Of 104 healthcare workers (HCWs) from whom hand cultures were obtained, P aer uginosa was isolated from three nurses. Cultures from nurses A-1 and A-2 gr ew genotype A and cultures from nurse B Brew genotype B, Nurse A-1 had long natural fingernails, nurse B had long artificial fingernails, and nurse A- 2 had short natural fingernails. On multivariate logistic regression analys is, exposure to nurse A-1 and exposure to nurse B were each independently a ssociated with acquiring a BSI or ETT colonization with P aeruginosa, but o ther variables, including exposure to nurse A-2, were not. CONCLUSION: Epidemiological evidence demonstrated an association between ac quiring P aeruginosa and exposure to two nurses. Genetic and environmental evidence supported that association and suggested, but did not Drove, a pos sible role for long. or artificial fingernails in the colonization of HCWs' hands with P aeruginosa. Requiring short natural fingernails in NICUs is a reasonable policy that might reduce the incidence of hospital-acquired inf ections (Infect Control Hosp Epidemiol 2000;21:80-85).