Use of DNA Fingerprinting To Assess Tuberculosis Infection Control

1 December 1998 | Volume 129 Issue 11 Part 1 | Pages 856-861

Background: DNA fingerprinting establishes the genetic relatedness of Mycobacterium tuberculosis isolates and has become a powerful tool in tuberculosis epidemiology.

Objective: To use DNA fingerprinting to assess the efficacy of current tuberculosis infection-control practices.

Design: Retrospective molecular and descriptive epidemiologic study.

Setting: A 700-bed urban public hospital that follows the Centers for Disease Control and Prevention (CDC) guidelines for tuberculosis infection control.

Patients: 183 patients who had positive cultures for M. tuberculosis from 1 April 1995 to 31 March 1996.

Results: 173 of 183 M. tuberculosis isolates from the study period underwent DNA fingerprinting. Fingerprinting revealed that five isolates represented false-positive cultures and that 91 (54%) of the remaining 168 isolates were in 15 DNA fingerprinting clusters, which ranged in size from 2 to 29 isolates. Risk factors for clustering were birth in the United States, African-American ethnicity, homelessness, substance abuse, and male sex. Retrospective epidemiologic analysis of inpatient and outpatient visits by the 91 patients who had clustered isolates revealed only one possible instance of patient-to-patient transmission.

Conclusions: The DNA fingerprinting of all M. tuberculosis isolates from a 1-year period revealed one possible instance of nosocomial transmission and five false-positive M. tuberculosis cultures. However, these results did not lead to changes in infection-control practices or in clinical care. The study findings do not support the use of DNA fingerprinting for nosocomial tuberculosis surveillance, but they suggest that compliance with the CDC tuberculosis infection-control guidelines may control patient-to-patient transmission in high-risk urban hospitals.

Author and Article Information

From Cook County Hospital, Rush Medical College, and Chicago Department of Public Health, Chicago, Illinois; and Michigan Department of Community Health, Lansing, Michigan.
Acknowledgments: The authors thank Dr. Arthur Evans, Dr. Stephen F. Sawin, and Ms. Jane K. Burke for assistance with statistical calculations and Ms. Josie Montgomery for processing of mycobacterial specimens.
Grant Support: The Michigan Department of Community Health Tuberculosis Genotyping Laboratory is supported by the Centers for Disease Control and Prevention National Tuberculosis Genotyping and Surveillance Network.
Requests for Reprints: Audrey L. French, MD, Division of Infectious Diseases/Durand 115, Cook County Hospital, 1835 West Harrison Street, Chicago, IL 60612.
Current Author Addresses: Drs. French, Welbel, and Weinstein: Division of Infectious Diseases/Durand 115, Cook County Hospital, 1835 West Harrison Street, Chicago, IL 60612.
Mr. Dietrich and Ms. Mosher: Michigan Department of Community Health, Division of Laboratory Services, 3500 North Martin Luther King Jr. Boulevard, PO Box 30035, Lansing, MI 48909.
Dr. Breall: Metro Infectious Disease Consultants, 2806 North Laramie, Chicago, IL 60641.
Dr. Paul: Chicago Department of Public Health, 2160 West Ogden, Chicago, IL 60612.
Dr. Kocka: Illinois Department of Public Health, 2121 West Taylor Street, Chicago, IL 60612.