Enumeration of Tubercle Bacilli in Sputum of Patients with Pulmonary Tuberculosis

Abstract

A method for precise microscopic enumeration of acid-fast bacilli in the sputum of patients with pulmonary tuberculosis is described. The total number of acid-fast bacilli and the number of culturable cell units of tubercle bacilli per milliliter of sputum were determined in 269 specimens from 28 patients collected prior to and/or during chemotherapy, to establish the usefulness of the procedure for evaluation of the effects of chemotherapy. Prior to or very early in the course of therapy, there was good agreement between microscopically and culturally measurable bacilli in 27 of 28 patients. Thereafter, there were systematic divergences in five patients and occasional divergences in most others. Yet, in general, in 20 of the 28 patients, the microscopically determined population provided a useful measure of the number of culturable tubercle bacilli present. Although the microscopic procedure does not allow species identification of mycobacteria or differentiation between viable and nonviable cells, it often provided, within hours rather than days or weeks, useful information on the residual burden of acid-fast bacilli in sputum during chemotherapy. The nature of the disease in those patients in whom microscopy failed to provide useful information is discussed.

Application of the C 18 -Carboxypropylbetaine Specimen Processing Method to Recovery of Mycobacterium avium subsp. paratuberculosis from Ruminant Tissue Specimens

“…When we compared the time-to-positive results of the tissue panel with the growth curves of the ATCC 19851 isolate, while bearing in mind that a positive smear requires approximately 10,000 AFB per ml (8,22), the times to positive of the tissue specimens in the 12B/EMP/VAN culture system were in excellent agreement with the respective smear results (data not shown). For example, of the 37 specimens that were smear positive and culture positive in 12B/EMP/VAN, 21 were reported to have a smear value of 4ϩ.…”

Improved Sensitivity of Sputum Smear Microscopy after Processing Specimens with C 18 -Carboxypropylbetaine To Detect Acid-Fast Bacilli: a Study of United States-Bound Immigrants from Vietnam

“…An increase in smear sensitivity must come from borderline smear-positive cases. If CB-18 processing is enhancing the number of bacilli recovered, then discordant specimens that were reported as direct smear-negative but CB-18 smear-positive will be those that did not reach the approximately 10,000-bacilli-per-ml threshold needed for detection by direct staining (6). Consistent with this was the observation that all of the 116 discrepant auramine smear specimens had low smear values.…”

Autofluorescence of Mycobacteria as a Tool for Detection of Mycobacterium tuberculosis

“…6). Hobby et al (15) related the bacillus microscopy results to the mycobacterial concentrations in the sputum of patients with TB. They established that sputum samples with microscopy scores of 3ϩ have from 1.08 ϫ 10 6 to 4.02 ϫ 10 7 bacilli ml Ϫ1 , while sputum samples with scores of 2ϩ have from 2.4 ϫ 10 4 to 1.41 ϫ 10 6 bacilli ml Ϫ1 .…”

“…The International Standards for Tuberculosis Care considers the microscopic analysis of two or three specimens per patient to be a cornerstone for the diagnosis of TB (13). Although light microscopy is inexpensive, easy to perform, and highly specific in areas where there is a high prevalence of TB, it is relatively insensitive, requiring Ն10 4 bacilli ml Ϫ1 of sputum to achieve a positive result (15,35). In addition, the procedure requires the observation of from 100 to 300 fields in order to obtain accurate results (31).…”