Demographic changes like increasing life expectancy, population growth, deterioration of living conditions in urban areas like over-crowding and epidemiological factors like HIV epidemic are expected to increase the incidence of TB, unless TB control efforts are intensified on a war footing. Poor treatment practices if continued may contribute to epidemic of multi-drug resistant TB (MDRTB) making the disease virtually incurable.

Fortunately, the ‘DOTS strategy’ now being expanded in the country has shown promise in terms of cure of infectious cases and hopes have been aroused of its control provided the strategy is implemented with full vigour.

Of the total smear positive cases presenting at health Institutions, about 69% can be detected by smear examination of first sputum specimen and another 20% by examination of second specimen. The additional case yield by subsequent specimen is minimal. Therefore, a minimum of two specimens should be examined for obtaining acceptable sensitivity of smear microscopy as a case finding tool.

Further, there is likelihood albeit small of single positive sputum smear result to be false positive. However, the chances of two positive results to be false positive are practically non-existent. Therefore, the criteria of at least two smear positive results to label a case as smear positive increases the specificity of the test. Since the bacilli are not excreted consistently in all specimens, at least three specimens should be examined to satisfy the above criterion.

A sputum smear is spread over an area of 200 mm² and contains about 0.01 ml of the specimen. Each oil-immersion field has an area of 0.02 mm². Therefore, there are 10,000 fields on the slide. If a specimen contains 5000 bacilli/ml, there will be 50 bacilli distributed over entire smear and 1 bacilli over 200 fields.

Considering that the bacilli are not distributed evenly over the smear, there must be at least 10,000 bacilli/ml to detect 1 bacillus over 200 fields.

Rinse mouth before sputum collection or collect specimen before food.

Use separate wooden stick for each smear preparation and stain each slide separately on a rack.

Use new slides. Nevertheless, the scratches on the slide can be differentiated as these occur in parallel rows and are found deeper.

Use fresh stains and preferably filter the stains before use.

Preferably, use distilled water to avoid false positive result from environmental mycobacteria.

Do not touch the slide with the objective of the microscope or the oil dropper.

Clean lens with a lens cleaning paper (not cotton) after exam of each slide.

Improper guidance to the patient resulting in poor quality of the sputum sample is the most common reason of a false negative result.

Bacilli may loose acid fastness if exposed to excessive heat (over heating while fixing the slide), direct sunlight, or long period of storage in hot and humid conditions.

Smear not prepared from blobs that contain dead caseous tissue discharged from cavity.

Too thin or too thick smear

Improper fixing

To short carbol-fuchsin staining or boiling it

Intensive counter staining

Erratic and brief examination

Administrative errors

 (i) Serological tests have poor sensitivity and specificity. Their sensitivity is highest in patients with smear positive disease and much lower among TB cases not detected by smear microscopy viz. sputum smear negative cases of pulmonary TB, extra-pulmonary TB, children diagnosed with TB and HIV infected TB cases. Also, these tests do not reliably distinguish active TB from dormant infection.

(ii) Amplification tests e.g. polymerase chain reaction (PCR) are 95% sensitive in smear positive cases and only 50% sensitive in smear negative and culture positive cases. Though specificity is high, it is lower under field conditions. In addition, inability to distinguish viable from dead bacilli and high cost dissuade their use in developing countries.

(iii) The Assay of cell-mediated immunity is highly complex.

This information is essential for prolongation of intensive phase by one month, which reduces risk of failure and relapse.

It is an important management tool and reflects on the quality of lab, quality of treatment observation during Intensive Phase and proportion of defaulters.

The smear status at the end of Intensive Phase also predicts the probability of cure.

If error is detected at the time of diagnosis, check for other smear results, X-ray and whether patient has been started on treatment. If the patient was missed on diagnosis, he should be traced and put on treatment.

If an error is detected on follow-up smear examinations, no change in treatment is undertaken based on the results of cross examination. To some extent, there are built-in mechanisms to handle this problem for e.g., re-examination of sputum smears after 5 months of treatment among those who are smear positive at 4 months. However, full efforts must be made to keep the errors on follow-up examinations to be minimum.

The treatment during continuous phase is partially supervised and adherence is sustained by continued motivation and health education of the patient. Operationally, it may not be feasible to supervise each dose of continuation phase. However, all those patients who have a history of being irregular, alcoholics etc., should be fully supervised. Other cases that are willing to be fully supervised during continuous phase should be encouraged.

Continuation Phase may be prolonged upto 7 months with INH & Rifampicin in cases of TBM, Miliary and Spinal TB

(i) Pyridoxin supplementation to pregnant females, diabetics,chronic alcoholics

(ii) Discourage alcohol consumption during treatment

(iii) Monitor for symptoms and signs consistent with hepatic damage

(iv) Liver function tests every 2 - 3 months for those at high risk

(v) Sterptomycin is contra - indicated during pregnancy

(vi) Monitor side effects of sterptomycin specially in elderly: tinnitus,

vertigo, hearing tests for higher frequencies which are affected first,

Romberg’s Test

(vii) Avoid loop diuretics, which potentiate side effects of ‘Streptomycin’.

(viii) Analgesics for arthralgia which usually does not require withdrawal of

anti-TB treatment.

(ix) In case of suspected preexisting ophthomological disease, assess visual

acuity and colour vision before starting treatment

(x) Stop ethambutol in case of side effects, which are reversible

(xi) Avoid ethambutol among children < 6 years

(xii) Avoid ‘Streptomycin’ and ‘Ethambutol’ in renal disease

(xiii) Avoid Antacids that decrease drug absorption

(xiv) Women to use non- hormonal contraceptive methods

(xv) In case of hypersensitivity reaction, withdraw treatment completely

and desensitize later

(xvi) Monitor steroids, oral anti-coagulants, anti-convulsants, oral hypoglycaemics, tranquilizers, theophylline, beta-blockers, calcium channel blockers, digoxin when given concurrently with Rifampicin.

Evaluate each patient by interview and clinical examination for emergence of side effects at the end of each month.

(i) These drugs are less efficacious and more toxic.

(ii) They possess cross resistance to first line drugs

(iii) Most patients needing such treatment are difficult to hold e.g. alcoholics, drug addicts, migrants etc,

(iv) Hospitalization is a must for observation and regularizing treatment. Ambulatory treatment is possible only after tolerance and regularity assured.

(v) It is irrational for any country to divert resources to treating with second line drugs until full potential of SCC regimen has been achieved.

Requirement of the reserve drugs indicates poor program.

In chronic liver disease, 2 EHRZ / 6 HR can be given unless there is severe liver damage. If ascitis and portal hypertension are present, treat with 2 SHE / 10 HE.

In case of acute hepatitis, the treatment may be deferred. If TB is serious, treat with 3 SE or 3 SE + ofloxacin followed by 6 HR when hepatitis is recovered.

2 HRZ / 4 HR is safe.

Decrease dose of Streptomycin & Ethambutol and adjust by renal function tests.