title: Investigation of a Candida guilliermondii Pseudo-outbreak Reveals a Novel Source of Laboratory Contamination.
abstract: Candida guilliermondiiwas isolated from sterile specimens with increasing frequency over a several-month period despite a paucity of clinical evidence suggesting trueCandidainfections. However, a health care-associated outbreak was strongly considered due to growth patterns in the microbiology laboratory that were more consistent with true infection than environmental contamination. Therefore, an extensive investigation was performed to identify its cause. With the exception of one case, patient clinical courses were not consistent with true invasive fungal infections. Furthermore, no epidemiologic link between patients was identified. Rather, extensive environmental sampling revealedC. guilliermondiiin an anaerobic holding jar in the clinical microbiology laboratory, where anaerobic plates were prereduced and held before inoculating specimens.C. guilliermondiigrows poorly under anaerobic conditions. Thus, we postulate that anaerobic plates became intermittently contaminated. Passaging from intermittently contaminated anaerobic plates to primary quadrants of aerobic media during specimen planting yielded a colonial growth pattern typical for true specimen infection, thus obscuring laboratory contamination. A molecular evaluation of theC. guilliermondiiisolates confirmed a common source for pseudo-outbreak cases but not for the one true infection. In line with Reason's model of organizational accidents, active and latent errors coincided to contribute to the pseudo-outbreak. These included organism factors (lack of growth in anaerobic conditions obscuring plate contamination), human factors (lack of strict adherence to plating order, leading to only intermittent observation of aerobic plate positivity), and laboratory factors (novel equipment). All of these variables should be considered when evaluating possible laboratory-based pseudo-outbreaks.
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA jekirby@bidmc.harvard.edu sbwright@bidmc.harvard.edu.|Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Kirby
authors.affiliation: Infectious Diseases Section, Medicine Service, VA Boston Healthcare System, Boston, Massachusetts, USA.|Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Westyn
authors.initials: W
authors.lastname: Branch-Elliman
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA.|Division of Infectious Diseases, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Mary T
authors.initials: MT
authors.lastname: LaSalvia
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Lorinda
authors.initials: L
authors.lastname: Longhi
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: MacKechnie
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Grigoriy
authors.initials: G
authors.lastname: Urman
authors.affiliation: Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Baldini
authors.affiliation: Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Fatima R
authors.initials: FR
authors.lastname: Muriel
authors.affiliation: Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Sullivan
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA.|Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.|Division of Infectious Diseases, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Yassa
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA.|Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.|Division of Infectious Diseases, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Howard S
authors.initials: HS
authors.lastname: Gold
authors.affiliation: OpGen, Inc., Gaithersburg, Maryland, USA.
authors.forename: Trevor K
authors.initials: TK
authors.lastname: Wagner
authors.affiliation: Division of Infectious Diseases and Pathology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Diekema
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA jekirby@bidmc.harvard.edu sbwright@bidmc.harvard.edu.|Division of Infection Control/Hospital Epidemiology, Silverman Institute for Health Care Quality and Safety, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.|Division of Infectious Diseases, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Wright
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002175:Candida / Q000302:isolation & purification*; D002177:Candidiasis / Q000175:diagnosis*; D004196:Disease Outbreaks; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D008297:Male; D008828:Microbiological Techniques / Q000379:methods*; D008875:Middle Aged; D055815:Young Adult
keywords: Candida; anaerobic; contamination; epidemiology; guilliermondii; optical mapping; pseudo-outbreak; pulsed-field gel electrophoresis; swan neck