0
Clinical Investigations: TUBERCULOSIS |

The Significance of the Persistent Presence of Acid-fast Bacilli in Sputum Smears in Pulmonary Tuberculosis*

Mohamed S. Al-Moamary, MD; William Black, MB; Elaine Bessuille, BSc; R. Kevin Elwood, MB; Sverre Vedal, MD, MSc
Author and Funding Information

*From the Respiratory Division, Department of Medicine (Drs. Al-Moamary, Elwood and Vedal) and Department of Pathology (Dr. Black), Vancouver Hospital & Health Sciences Centre, University of British Columbia, Vancouver, British Columbia, Canada; and Division of Tuberculosis Control (Dr. Elwood) and Mycobacteriology Section, Provincial Laboratory (Dr. Black and Ms. Bessuille), British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada.

Correspondence to: Sverre Vedal, MD, Respiratory Division, 2775 Heather St, Vancouver, BC, Canada V5Z 3J5; e-mail: vedal@interchg.ubc.ca



Chest. 1999;116(3):726-731. doi:10.1378/chest.116.3.726
Text Size: A A A
Published online

Study objectives: Identification of acid-fast bacilli (AFB) in the sputum smear at the completion of tuberculosis therapy is in some settings considered evidence of treatment failure. However, some patients with pulmonary tuberculosis (TB) will have positive smear results with negative sputum culture results at the end of therapy. The objectives of this study were to estimate the prevalence of persisting positive sputum smear results in patients with TB and to identify characteristics that distinguish patients with persistently positive sputum smear results who also had negative sputum culture results from patients identified as treatment failures.

Design: A population-based, historical cohort study with nested case control study.

Setting: British Columbia Division of Tuberculosis Control central case registry.

Patients: All 428 patients with culture-proven pulmonary TB in British Columbia over 7 years with sputum that was positive for AFB.

Methods: Review of laboratory data of all 428 patients, as well as clinical data of a subset of 30 patients with persistently positive smear results beyond 20 weeks.

Results: Sputum smears were positive for AFB in 205 patients (48%) at 4 weeks, in 30 patients (7%) at 20 weeks, and in 12 patients (3%) at 36 weeks. Of the patients with smear results that were persistently positive at 20 weeks, 23 (77%) had negative sputum culture results and 7 (23%) had positive sputum culture results (ie, they were treatment failures). Patients identified as treatment failures had more localized disease as shown on chest radiographs, had less radiographic improvement at follow-up, had a higher prevalence of drug resistance, and were less compliant with medications than patients with persistently positive smear results and negative culture results. No subject with a negative culture result relapsed over the 6- to 48-month observation period.

Conclusion: Sputum that is persistently positive for AFB in patients in developed countries is more likely to be associated with negative culture results than with treatment failure.

Figures in this Article

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Figures

Tables

References

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543