https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(98)03406-0.pdf

Transmission of Mycobacterium tuberculosis from patients smear-negative for acid-fast bacilli

The risk of progression from exposure to the tuberculosis bacilli to the development of active disease is a two-stage process governed by both exogenous and endogenous risk factors. Exogenous factors play a key role in accentuating the progression from exposure to infection among which the bacillary load in the sputum and the proximity of an individual to an infectious TB case are key factors. Similarly endogenous factors lead in progression from infection to active TB disease. Along with well-established risk factors (such as human immunodeficiency virus (HIV), malnutrition, and young age), emerging variables such as diabetes, indoor air pollution, alcohol, use of immunosuppressive drugs, and tobacco smoke play a significant role at both the individual and population level. Socioeconomic and behavioral factors are also shown to increase the susceptibility to infection. Specific groups such as health care workers and indigenous population are also at an increased risk of TB infection and disease. This paper summarizes these factors along with health system issues such as the effects of delay in diagnosis of TB in the transmission of the bacilli.

/pdf/risk-factors-for-tuberculosis-51hcda4lht.pdf

Risk Factors for Tuberculosis

Counts of colony-forming units of Mycobacterium tuberculosis in sputum were done on selective medium during the first 2 wk of treatment of 124 patients with pulmonary tuberculosis. The 27 chemotherapy regimens studied included daily administration of thiacetazone, p-aminosalicylic acid, pyrazinamide, rifampin, streptomycin, ethambutol, and isoniazid alone and certain 2-drug, 3-drug, and 4-drug combinations. Thiacetazone and p-aminosalicylic acid appeared to be only bacteriostatic. The mean fall in counts and the differences between regimens containing the remaining bactericidal drugs were greater during the first 2 days of treatment than during the remaining 12 days. The early (0-to-2-day) falls were much larger with isoniazid than with other drugs. Rifampin was less bactericidal, and may have reduced the bactericidal activity of the 3-drug and 4-drug combinations, including isoniazid. Although streptomycin and pyrazinamide were only slightly bactericidal alone or in a 2-drug combination, the 3-drug regim...

The early bactericidal activity of drugs in patients with pulmonary tuberculosis.

The peritoneum is one of the most common extrapulmonary sites of tuberculous infection. Peritoneal tuberculosis remains a significant problem in parts of the world where tuberculosis is prevalent. Increasing population migration, usage of more potent immunosuppressant therapy and the acquired immunodeficiency syndrome epidemic has contributed to a resurgence of this disease in regions where it had previously been largely controlled. Tuberculous peritonitis frequently complicates patients with underlying end-stage renal or liver disease that further adds to the diagnostic difficulty. The diagnosis of this disease, however, remains a challenge because of its insidious nature, the variability of its presentation and the limitations of available diagnostic tests. A high index of suspicion is needed whenever confronted with unexplained ascites, particularly in high-risk patients. Based on a systematic review of the literature, we recommend: tuberculous peritonitis should be considered in the differential diagnosis of all patients presenting with unexplained lymphocytic ascites and those with a serum-ascites albumin gradient (SAAG) of <11 g/L; culture growth of Mycobacterium of the ascitic fluid or peritoneal biopsy as the gold standard test; further studies to determine the role of polymerase chain reaction, ascitic adenosine deaminase and the BACTEC radiometric system for acceleration of mycobacterial identification as means of improving the diagnostic yield; increasing utilization of ultrasound and computerized tomographic scan for the diagnosis and as a guidance to obtain peritoneal biopsies; low threshold for diagnostic laparoscopy; treatment for 6 months with the first-line antituberculous drugs (isoniazid, rifampicin, ethambutol and pyrazinamide) in uncomplicated cases.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2036.2005.02645.x

Systematic review: tuberculous peritonitis--presenting features, diagnostic strategies and treatment.

Transmission of tubercle bacilli: The effects of chemotherapy.

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.

Michael D. Iseman

Papers

Enumeration of Tubercle Bacilli in Sputum of Patients with Pulmonary Tuberculosis