OBJECTIVE: To investigate an outbreak of Burkholderia cepacia.
DESIGN: Observational study and chart review.
PATIENTS: Adult non-cystic fibrosis (CF) patients.
SETTING: Intensive care units (ICUs) at a university-affiliated teaching ho
METHODS: As part of the epidemiological investigation, we conducted a chart
review and collected environmental samples. A review of work schedules of
healthcare workers also was performed. We used B cepacia selective agar for
preliminary screening for all isolates, which subsequently were confirmed
as members of the B cepacia complex by polyphasic analysis employing conven
tional biochemical reactions and genus- and species-specific polymerase cha
in reaction assays. Pulsed-field gel electrophoresis, randomly amplified po
lymorphic DNA typing, and automated ribotyping were used to genotype the is
olates. As part of the intervention, contact isolation precautions were ini
tiated for all patients identified as having had a culture positive for B c
RESULTS: Between September 1997 and September 1999, B cepacia was isolated
from 31 adult patients without CF in ICUs at a university-affiliated teachi
ng hospital. Based on geographic clustering and genotypic analysis, three d
istinct clusters were observed involving 20 patients. Isolates from 17 of t
hese patients were available for testing and were found to be of the same s
train (outbreak strain). Further taxonomic analysis indicated that the outb
reak strain was B cepacia complex genomovar III. Twelve (71%) of the 17 pat
ients were judged to be infected, and 5 (29%) were colonized with this stra
in. Six of 200 environmental cultures from multiple sources in the hospital
's ICUs yielded B cepacia. Two of these isolates, both recovered from rooms
of colonized patients, were the same genotype as the outbreak strain recov
ered from patients.
CONCLUSION: Despite an extensive investigation, the source of the B cepacia
clone involved in this outbreak remains unknown. The spatial and temporal
pattern of cases suggests that cross-transmission of a genetically related
strain contributed to clustering among patients. The initiation of contact
isolation may have limited the extent of this transmission. Additional stud
ies are needed to elucidate better the epidemiology of nosocomial B cepacia
infection among non-CF adult patients (Infect Control Hosp Epidemiol 2001;