title: Mycobacterium avium complex endocarditis: spurious diagnosis resulting from laboratory cross contamination.
abstract: Contamination between specimens within clinical microbiology laboratories may be responsible for spurious outbreaks of mycobacterial infections. We report the case of a patient who had culture-negative endocarditis and whose cardiac tissue obtained at surgery yielded Mycobacterium avium complex (MAC). Epidemiologic investigation suggested cross contamination probably occurred during processing of the sputum specimens of a patient with pulmonary MAC disease and the cardiac samples from our patient; molecular strain typing showed the isolates from both patients to be identical. When mycobacterial infection rates increase or an unexpected case of mycobacterial infection occurs, the clinician should be alert to the possibility of cross contamination in the laboratory as a possible explanation.
authors.affiliation: Department of Internal Medicine, Department of Veterans Affairs Medical Center, University of Michigan Medical School, Ann Arbor 48105, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Hedderwick
authors.forename: H F
authors.initials: HF
authors.lastname: Bonilla
authors.forename: N L
authors.initials: NL
authors.lastname: Barg
authors.forename: R D
authors.initials: RD
authors.lastname: Arbeit
authors.forename: C A
authors.initials: CA
authors.lastname: Kauffman
mesh_terms: D003951:Diagnostic Errors; D016521:Electrophoresis, Gel, Pulsed-Field; D004697:Endocarditis, Bacterial / Q000175:diagnosis* / Q000209:etiology*; D004866:Equipment Contamination; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000166:cytology / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000150:complications / Q000175:diagnosis*; D013048:Specimen Handling / Q000009:adverse effects*