Background. Bloodstream infections with Pseudomonas aeruginosa have been well-described in neonatal intensive care units (NICU) and have resulted in the temporary closure of some nurseries to new admissions. Nosocomial transmission of these infections has been verified by fingerprint analysis of the isolates. We utilized molecular fingerprinting to identify the source of bloodstream infections in an NICU and used this information to apply infection control measures that allowed the nursery to stay open and continue to accept referrals.
Methods. In June 1998 three premature infants transferred to our hospital (Hospital A) from Hospitals B and C had bloodstream infections with P. aeruginosa. Subsequently one additional neonate transferred from Hospital B was colonized with P. aeruginosa. Random amplification of polymorphic deoxyribonucleic acid (RAPD) was performed on the four isolates. All transfers from Hospital B were cultured, and surveillance programs were instituted in Hospitals A and B. Targeted infection control measures for all transfers were implemented.
Results. The four isolates were the same clone by RAPD. Investigation of the environment in Hospital A did not identify any source of the organism. Surveillance cultures on 49 neonates at Hospital A revealed only one patient colonized at an endotracheal tube. This patient was also a transfer from Hospital B. Results from Hospital B identified 4 of 40 (10%) neonates colonized. All isolates were clones identical with the bloodstream isolates from the neonates with bloodstream infections. Infection control measures for all babies transferred from Hospital B resulted in no new cases of P. aeruginosa bacteremia during the next 5 years.
Conclusions. The use of molecular fingerprinting of isolates of P. aeruginosa allowed for a prompt and directed infection control plan to be implemented in Hospitals A and B. It also allowed the NICU in Hospital A to continue to accept referrals from other hospitals and to implement a targeted infection control plan for patients transferred from Hospital B.