Role of environmental surveillance in determining the risk of hospital-acquired legionellosis: a national surveillance study with clinical correlations.
OBJECTIVE
Hospital-acquired Legionella pneumonia has a fatality rate of 28%, and the source is the water distribution system. Two prevention strategies have been advocated. One approach to prevention is clinical surveillance for disease without routine environmental monitoring. Another approach recommends environmental monitoring even in the absence of known cases of Legionella pneumonia. We determined the Legionella colonization status of water systems in hospitals to establish whether the results of environmental surveillance correlated with discovery of disease. None of these hospitals had previously experienced endemic hospital-acquired Legionella pneumonia.


METHODS
Cohort study.


METHODS
Twenty US hospitals in 13 states.


METHODS
Hospitals performed clinical and environmental surveillance for Legionella from 2000 through 2002. All specimens were shipped to the Special Pathogens Laboratory at the Veterans Affairs Pittsburgh Medical Center.


RESULTS
Legionella pneumophila and Legionella anisa were isolated from 14 (70%) of 20 hospital water systems. Of 676 environmental samples, 198 (29%) were positive for Legionella species. High-level colonization of the water system (30% or more of the distal outlets were positive for L. pneumophila) was demonstrated for 6 (43%) of the 14 hospitals with positive findings. L. pneumophila serogroup 1 was detected in 5 of these 6 hospitals, whereas 1 hospital was colonized with L. pneumophila serogroup 5. A total of 633 patients were evaluated for Legionella pneumonia from 12 (60%) of the 20 hospitals: 377 by urinary antigen testing and 577 by sputum culture. Hospital-acquired Legionella pneumonia was identified in 4 hospitals, all of which were hospitals with L. pneumophila serogroup 1 found in 30% or more of the distal outlets. No cases of disease due to other serogroups or species (L. anisa) were identified.


CONCLUSIONS
Environmental monitoring followed by clinical surveillance was successful in uncovering previously unrecognized cases of hospital-acquired Legionella pneumonia.
Stout
Janet E
JE
VA Pittsburgh Healthcare System, Pittsburgh, PA, USA.
Muder
Robert R
RR
Mietzner
Sue
S
Wagener
Marilyn M
MM
Perri
Mary Beth
MB
DeRoos
Kathleen
K
Goodrich
Dona
D
Arnold
William
W
Williamson
Theresa
T
Ruark
Ola
O
Treadway
Christine
C
Eckstein
Elizabeth C
EC
Marshall
Debra
D
Rafferty
Mary Ellen
ME
Sarro
Kathleen
K
Page
Joann
J
Jenkins
Robert
R
Oda
Gina
G
Shimoda
Kathleen J
KJ
Zervos
Marcus J
MJ
Bittner
Marvin
M
Camhi
Sharon L
SL
Panwalker
Anand P
AP
Donskey
Curtis J
CJ
Nguyen
Minh-Hong
MH
Holodniy
Mark
M
Yu
Victor L
VL
D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004784:Environmental Monitoring / Q000379:methods*; D062665:Epidemiological Monitoring; D006801:Humans; D017053:Infection Control / Q000379:methods / Q000592:standards; D007875:Legionella / Q000302:isolation & purification*; D007876:Legionellosis / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D015995:Prevalence; D011446:Prospective Studies; D018570:Risk Assessment; D012308:Risk Management; D018571:Sentinel Surveillance; D014481:United States / Q000453:epidemiology; D014871:Water Microbiology; D014881:Water Supply