Investigation of Increase in Pseudomonas aeruginosa Infections in the Neonatal Intensive Care Unit, November 2001–December 2003

ISSUE: In November 2001, the number of Pseudomonas aeruginosa isolates (PAI) increased in the NICU from 38 in 2000 to 67 (a 43.3% increase). Despite meeting with the NICU leaders to increase awareness of basic infection prevention measures, the increase in PAI continued. Respiratory PAI increased 40% in 2001 compared to 2000. In August 2002, more aggressive interventions were begun. PROJECT: Environmental cultures (EC) were obtained. The NICU was cleaned thoroughly on several occasions between cultures. Water restrictions were imposed for patients and staff. Concurrently, hand cultures (HC) were done on all staff members present in the NICU. Pulsed-field gel electrophoresis (PFGE) was performed on the positive environmental and staff cultures and was compared to the PFGE done on the patients. In May 2003, an additional intervention was initiated: changing in-line suction catheters every 24 hours instead of three times/week. RESULTS: Forty percent (40%) of patient isolates and 27% of EC grew Pseudomonas spp., and 7% of the HC grew Pseudomonas. All patient isolates, HC, and EC were unique. One HC isolate matched one infant and another matched a second infantʹs isolate. Although we saw intermittent cases after May 2003, our PAI decreased from 29 in 2002 to 13 in 2003 (55%). Our incidence rate of PAI from endotracheal/nasal suction decreased from 2.4 per 1000 patient days in 2002, to 0.7 in 2003. This is less than our pre-outbreak rate of 1.05. LESSONS LEARNED: Despite several studies indicating that weekly changes of in-line suction catheters is not associated with an increase in ventilator-associated pneumonia in adults, little is known about neonates. In one study looking at neonates, Freytag et al. found that changing the catheter every 72 hours significantly enhanced microbial growth on the catheters and appreciably increased colonization of the lower respiratory tract. Cordero et al. found that when in-line suction catheters were changed daily, colonization with gram-negative organisms occurred significantly less frequently than in infants who were suctioned with single-use catheters. Because changing the respiratory catheter every 24 hours increases costs, more study in this vulnerable population is needed.