Outbreaks of infection in neonatal intensive care units (NICU)

An Outbreak ofPseudomonas aeruginosaPneumonia and Bloodstream Infection Associated With Intermittent Otitis Externa in a Healthcare Worker

Objectives:

To investigate an outbreak ofPseudomonas aeruginosapneumonia and bloodstream infection among four neonates, determine risk factors for infection, and implement preventive strategies.

Design:

Retrospective case finding; prospective surveillance cultures of patients, personnel, and environmental sites; molecular typing by pulsed-field gel electrophoresis; and a matched case-control study.

Patients and Setting:

Neonates in the level-III neonatal intensive care unit of a tertiary-care pediatric institution.

Interventions:

Cohorting of patients with positive results forP. aeruginosa, work restrictions for staff with positive results, implementation of an alcohol-based hand product, review of infection control policies and procedures, and closure of the unit until completion of the investigation.

Results:

Seven (4%) of 190 environmental cultures and 5 (3%) of 178 cultures of individual healthcare workers' hands grewP. aeruginosa. All four outbreak isolates and one previous bloodstream isolate were genotypically identical, as were theP. aeruginosaisolates from the hands and external auditory canal of a healthcare worker with intermittent otitis externa. Four of 5 case-patients versus 5 of 15 matched control-patients had been cared for by this healthcare worker (P= .05). The healthcare worker was treated and no further cases occurred.

Conclusions:

These findings suggest that a healthcare worker with intermittent otitis externa may have caused this cluster of fatalP. aeruginosainfections, adding the external ear to the list of colonized body sites that may serve as a source of potentially pathogenic organisms.

Outbreaks in neonatal intensive care units - they are not like others

BACKGROUND

Outbreaks of health care-associated infections in neonatal intensive care units (NICUs) are frequent and have received more attention in medical literature than outbreaks from other types of intensive care units (ICUs). The objective of this systematic review was to identify differences between outbreaks of health care-associated infections in NICUs and other ICUs as reported to date in the medical literature.

METHODS

Screening the outbreak database (http://www.outbreak-database.com), a systematic comparison of outbreaks was performed with the following categories: causing pathogen, type of infection, sources identified, and measures taken to stop the outbreak.

RESULTS

Two hundred and seventy-six outbreaks were reported from NICUs and 453 from other ICU types. Enterobacteriaceae were significantly more often responsible for NICU outbreaks, whereas nonfermenting bacteria are more frequently identified in other ICU types. On average, 23.9 patients and 1.8 health care workers were involved in NICU outbreaks. Average mortality in NICU outbreak was 6.4% (1.5 newborns on average). In 48.6% of NICU outbreaks the authors were unable to identify the sources compared with 38.0% in other ICU outbreaks. The most important infection control measures were significantly more often implemented in NICUs than in other ICUs.

CONCLUSIONS

Systematic outbreak analysis is essential for gaining insights into the control of NICU outbreaks.

Surveillance of Pseudomonas aeruginosa-isolates in a neonatal intensive care unit over a one year-period

Outbreaks of gram-negative bacteria such as Pseudomonas aeruginosa in neonatal intensive care units (NICU) can be life-threatening to pre-term infants, which are highly susceptible to serious infections with bacteria. Forty-two ventilated neonates in the NICU of the University Children's Hospital of Tuebingen were found to be colonized (n = 40) or infected (n = 2) with P. aeruginosa within a sampling period of one year. To investigate the colonization patterns and identify potential outbreak sources, epidemiological investigations, environmental surveillance and typing by serotyping and pulsed-field gel electrophoresis of the recovered isolates were performed. The investigation demonstrated a genetically related cluster of P. aeruginosa isolates during the surveillance period in 39 neonates and a second cluster at the end of the period in two neonates. A third strain representing a genetically distinct group was found in only one patient. Environmental investigations demonstrated the presence of P. aeruginosa in the ventilation equipment of 22 patients: binasal prongs (n = 22), water reservoir (n = 9), and heater (n = 1). In one case, P. aeruginosa was found in breast milk. Other environmental investigations revealed no P. aeruginosa. Although no evidence for a unique source was found, a series of intervention steps were initiated by the NICU personnel, medical microbiologists and infection control experts. The intervention steps included reinforced training of health care staff and a change from chemical to thermal disinfection of binasal prongs. Implementation of these measurements successfully stopped the recurrent occurrence of P. aeruginosa colonization.

Neonatal infections with Pseudomonas aeruginosa associated with a water-bath used to thaw fresh frozen plasma

In our 15-bed neonatal intensive care unit (NICU), four new-borns were found to be colonized or infected with Pseudomonas aeruginosa within a period of one week. To identify the outbreak source, three independent studies were performed: epidemiological investigation, environmental surveillance and genotypic typing of isolates. Although epidemiological investigation by a case-control study revealed no conclusive results, the transfusion of fresh frozen plasma (FFP) and human albumin (HA) appeared to be the factor with highest risk. Environmental surveillance and random amplification of polymorphic DNA (RAPD) of isolates identified a water-bath used to warm FFP and HA as the likely reservoir for the outbreak. Further spread of the organism did not occur after elimination of this water-bath from the NICU. RAPD identified in addition an isolate from an infant hospitalized in the NICU five months before the outbreak with a pattern matching the one of the outbreak cluster.