An outbreak of Legionella micdadei pneumonia in transplant patients: evaluation, molecular epidemiology, and control.
OBJECTIVE
To describe a nosocomial outbreak of Legionella micdadei pneumonia in transplant patients and to characterize the source of the outbreak and the control measures utilized.


METHODS
We performed retrospective Legionella micdadei serologic testing to enhance case finding in transplant patients with pneumonia that lacked a documented microbial etiology, as well as prospective environmental surveillance of water sites and testing for Legionella in clinical specimens.


RESULTS
During a 3-month period, 12 cases of Legionella micdadei pneumonia were identified either by culture or serologic testing among 38 renal and cardiac transplant patients. Legionella micdadei isolates from hot water sources were found by pulsed-field gel electrophoresis to have a DNA banding pattern that was identical to the isolates from the first 3 culture-positive cases and from 2 cases that occurred 16 months later.


CONCLUSIONS
Hospitals caring for organ transplant recipients and other immunosuppressed patients must be aware of the possibility of environmental sources of outbreaks of Legionella infection. A first-line screen with the Legionella urine antigen test will identify Legionella pneumophila serogroup 1. However, specific cultures in outbreak situations should be considered to identify other Legionella pneumophila serotypes and the nonpneumophila Legionella species.
Knirsch
C A
CA
Department of Medicine, College of Physicians & Surgeons, Columbia University, New York, New York, USA.
Jakob
K
K
Schoonmaker
D
D
Kiehlbauch
J A
JA
Wong
S J
SJ
Della-Latta
P
P
Whittier
S
S
Layton
M
M
Scully
B
B
D000328:Adult; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control; D004196:Disease Outbreaks / Q000517:prevention & control; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D016027:Heart Transplantation; D006801:Humans; D017053:Infection Control / Q000379:methods*; D016030:Kidney Transplantation; D007875:Legionella / Q000235:genetics / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009519:New York City / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology / Q000382:microbiology*; D012189:Retrospective Studies