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Volume 8, Number 11—November 2002
THEME ISSUE
Tuberculosis Genotyping

Tuberculosis Genotyping Network, United States

A Prospective, Multicenter Study of Laboratory Cross-Contamination of Mycobacterium tuberculosis Cultures

Robert M. Jasmer*Comments to Author , Marguerite Roemer†, John Hamilton‡, John Bunter§, Christopher R. Braden¶, Thomas M. Shinnick¶, and Edward P. Desmond**
Author affiliations: *San Francisco General Hospital Medical Center and University of California, San Francisco, California, USA; †San Francisco General Hospital, San Francisco, California, USA; ‡Santa Clara Valley Medical Center, San Jose, California, USA; §Solano County Public Health Laboratory, Vallejo, California, USA; ¶Centers for Disease Control and Prevention, Atlanta, Georgia, USA; **California Department of Health Services, Berkeley, California, USA;

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Table

Clinical and laboratory characteristics of patients suspected of having false-positive cultures for Mycobacterium tuberculosisa

Patient Lab Specimen
type Initial or follow-up specimen Sputum smear result Clinical signs and symptoms Comments Panel decision Final diagnosis
1 1 Sputum Initial Negative 36-yr-old man with AIDS hospitalized with cough, dyspnea, right lower lobe infiltrate; he improved with trimethoprim and sulfamethoxazole alone Genotype of isolate matched that of another patient whose specimen was processed same day Cross-contamination Bacterial pneumonia
2 2 Sputum Initial 2+ Positive 28-yr-old man with HIV infection with fever, cough, right lower lobe infiltrate; improved with ceftazidime Genotype of isolate matched that of another patient hospitalized on the same ward Mislabeled specimen Bacterial pneumonia
3 2 Sputum Initial Negative 31-yr-old woman hospitalized with cough, left lower lobe infiltrate, and leukocytosis; chest radiograph showed improvement with clindamycin and ofloxacin Genotype of isolate matched that of another patient whose specimen was processed same day Cross-contamination Bacterial pneumonia
4 2 Sputum Initial Negative 44-yr-old man hospitalized with cough and right lower lobe infiltrate; improved with levofloxacin before anti-TB therapy initiated Genotype of isolate matched that of another patient whose specimen in the BACTEC instrument immediately preceded the case patient Cross-contamination Lung abscess
5 2 Sputum Follow-up Negative 68-yr-old woman newly immigrated from China with cough; chest radiograph showed bi-apical fibronodular changes Genotype of second isolate >30 days later did not match that of initial isolate or any other isolate in database Mislabeled specimen or mixed infection Bacterial pneumonia versus TB with mixed infection]
6 2 Sputum Initial 4+ Positive 82-yr-old man with cough, fever; chest radiograph showed chronically increased right mid-lung interstitial markings Genotype of isolate matched that of another patient hospitalized on the same ward Mislabeled specimen or cross-contamination Bacterial pneumonia
7 2 Sputum Initial Negative 27-yr-old woman with upper respiratory symptoms; chest radiograph was normal Genotype of isolate matched that of another patient whose specimen was processed same day Cross-contamination Upper respiratory tract infection
8 2 Sputum Initial Negative 44-yr-old man with hemoptysis and known pulmonary metastases of squamous cell carcinoma of trachea; chest radiograph showed three large cavities with air-fluid levels; bronchoscopy culture grew H. influenzae, and patient improved on antibiotics alone Genotype of isolate matched that of another patient whose specimen was processed same day Cross-contamination Lung abscess
9 2 Broncho-alveloar lavage Initial Negative 55-yr-old woman hospitalized with dyspnea and left lower lobe infiltrate; she improved with broad-spectrum antibiotics alone Genotype of isolate matched that of another patient whose specimen was processed same day Cross-contamination Bacterial pneumonia
10 3 Sputum Follow-up Negative 34-yr-old homeless man with HIV infection, fever, and cervical lymphadenopathy; chest radiograph showed left lung nodule Genotype of initial isolate matched that of another homeless TB patient; follow-up specimen (35 days later) had a unique genotype TB TB

aLab, laboratory; TB, tuberculosis; H. influenzae, Haemophilus influenzae.

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