Pulmonary Tuberculosis Diagnosis

Tuberculosis

• Pulmonary tuberculosis is an infectious disease that spreads through airborne droplet nuclei.
• Sputum positive pulmonary TB patients are the primary source of infection.
• An untreated smear positive pulmonary TB patient can infect 10-15 people annually.
• Identifying and diagnosing TB suspects early is crucial for effective treatment and preventing further spread.

Diagnosis of Pulmonary Tuberculosis

Suspected Case

• Most TB patients seek medical attention promptly after symptoms appear.
• All adult patients with respiratory symptoms should be screened for TB symptoms.
• Persistent cough lasting three weeks or more is the most common TB symptom which usually involves expectoration.
• Other symptoms may include weight loss, chest pain, fatigue, shortness of breath, fever (especially in the evening), blood in sputum, loss of appetite, and night sweats.
• Approximately 2-3% of new adult outpatients in general health facilities may have coughs lasting over 3 weeks.
• About 10% of suspects are expected to have sputum positive pulmonary TB.

Case Finding Tools

• Sputum smear microscopy, chest X-rays, and cultures of Mycobacterium tuberculosis bacilli are key tools for diagnosing pulmonary TB.
• Sputum smear microscopy is used for diagnosis, monitoring, and defining cure.
• Sputum smear microscopy is a diagnostic tool used for case detection as part of the RNTCP.
• At least 50% of new pulmonary TB patients are expected to be smear-positive if good diagnostic practices are followed.
• 10-15% of culture-positive cases remain undiagnosed, and 40% of patients diagnosed via X-ray do not have active TB, due to non-specific shadows
• Chest X-rays support microscopy.
• Cultures of Mycobacterium tuberculosis bacilli are highly sensitive and specific.
• Culture requires specialized labs and takes weeks, but is useful for diagnosing drug resistant TB.
• Tuberculin tests may help diagnose TB in children, for whom a positive test likely indicates recent infection and a higher risk of developing the disease.
• Tuberculin tests are not useful for diagnosing adult pulmonary TB in India.

Diagnostic Algorithm

• Cough lasting for three weeks or more requires diagnostic testing.
• Three sputum smears are required for diagnosis.
• If 2 or 3 smears are positive, the patient is presumed to have TB.
• if 3 smears are negative, antibiotics are administered for 10-14 days.
• For a persistent cough, repeat sputum examinations.
• If at least one is positive, perform X-ray.
• If X-ray shows TB symptoms, then begin anti-TB treatment.
• If X-ray shows no TB symptoms, then the patient is negative for TB.

Important Guidelines

• Raise community awareness among medical professionals and staff to recognise persistent coughs and to gather and check three sputum samples for TB diagnosis.
• Examine household contacts of smear-positive TB patients, regardless of cough duration, and examine extra-pulmonary TB cases with any cough duration.
• Collect at least 3 sputum specimens over 2 consecutive days for microscopy; one at the first visit, another at home the next morning, and a third during the second lab visit.
• Explain sputum collection reasons to patients before collecting the specimen.
• Lab technicians must ensure complete patient address on the lab form, and collect specimens under health worker guidance.
• Examine sputum specimens on the same day or within a week if transported to a designated microscopy centre.
• Store sputum samples in a cool place or refrigerator.
• All specimens should be examined in the nearest designated microscopy center using the Ziehl-Neelsen method

Sputum Smear Interpretation

• 10 AFB per oil immersion field corresponds to a positive result, graded as 3+, with 20 fields examined.

• 1-10 AFB per oil immersion field corresponds to a positive result, graded as 2+, with 50 fields examined.
• 10-99 AFB per 100 oil immersion fields corresponds to a positive result, graded as 1+, with 100 fields examined.
• 1-9 AFB per 100 oil immersion fields corresponds to a positive result, graded as Scanty*, with 100 fields examined.
• No AFB in 100 oil immersion fields corresponds to a negative result, with 100 fields examined.
• Effective quality assurance (QA) of the RNTCP sputum smear microscopy network is vital and includes internal quality control (QC), external quality assessment (EQA), and continuous quality improvement (QI).

Treatment of Tuberculosis

• After a TB diagnosis, the MO decides the treatment regimen based on sputum smear results, previous anti-TB treatment, disease classification (pulmonary/extra-pulmonary), and severity of illness.
• TB treatment aims to decrease mortality and morbidity by ensuring cure, minimizing relapses, and preventing drug resistance.
• Other goals are to reduce infections, break the chain of transmission, and minimize drug side effects.
• RNTCP achieves these objectives through intermittent (thrice weekly) treatment regimens under direct observation, for both pulmonary and extra-pulmonary TB.

RNTCP Treatment Categories

• Category I: New sputum smear-positive, seriously ill new sputum smear-negative, or seriously ill new extra-pulmonary patients receive a regimen of 2H3R3Z3E3+4H3R3.
• Category II: Sputum smear-positive relapse, failure, or treatment after default patients receive a regimen of 2H3R3Z3E3S3+1H3R3Z3E3+5H3R3E3.
• Category III: New, not seriously ill sputum smear-negative patients receive a regimen of 2H3R3Z3+4H3R3.
• Notation:
  • Numbers before letters indicate treatment months.
  • Subscripts after letters indicate doses per week.
  • Drug dosage strengths are as follows:
    • H (Isoniazid 600 mg)
    • R (Rifampicin 450 mg)
    • Z (Pyrazinamide 1500 mg) -E (Ethambutol 1200 mg)
    • S (Streptomycin 750 mg).
    • Patients over 50 receive streptomycin 500 mg and those under 30 kg receive drugs per body weight.

Drugs and Dosages

• Isoniazid: 600 mg (2 pills in combipack).
• Rifampicin: 450 mg (1 pill in combipack).
• Pyrazinamide: 1500 mg (2 pills in combipack).
• Ethambutol: 1200 mg (2 pills in combipack).
• Streptomycin: 0.75 mg.
• Drugs are supplied in patient-wise boxes (PWB) with color codes: Red (CAT I), Blue (CAT II), and Green (CAT III).
• Each PWB includes pouches for the intensive phase (A) and continuation phase (B).
• Intensive phase packs contain medicines for each dose, while continuation phase blister packs contain a week's supply of medication.
• Drugs for extending the intensive phase are supplied separately.
• Adults receive recommended pill/capsule numbers regardless of weight.
• Patients over 60 kg requires an extra 150mg capsule of rifampicin.
• Patients over 50 years old receive streptomycin 500mg and those under 30 kg receive drugs as per body weight.

Directly Observed Treatment (DOT) Guidelines

• DOT is a key part of the DOTS strategy, in which an observer watches and supports the patient through the entire course with the correct drugs, doses, and intervals.
• The DOT provider should be acceptable, accessible, and accountable to the health system,.
• Anyone other than family members can administer DOT.
• Every dose during the intensive phase, must be taken with the DOT provider.
• After taking the drugs under direct observation, the treatment card is marked.
• Missed doses are marked, traced, and given the next day, if medication is missed on schedule.
• If doses are missed for two successive days during the IP, then those doses must be made up at the end of the scheduled period, thus, prolonging the treatment.
• During the continuation phase, patients collect drugs weekly from the DOT center.
• One dose each week is observed directly, and the other two administered by the patients themselves.
• 'X' marks days when drugs are swallowed under direct observation, and a line marks self-administered days.
• Patients must bring the used blister pack during the next collection.
• With a single day delay during the continuation phase, then the dose is given and other doses continue as scheduled.
• With a multiple day delay (2 or more) during the continuation phase, the missed dose is marked and administered.
• Missed doses must be made up at the end of the scheduled period which prolongs the treatment duration.
• Patients who miss a dose should be contacted and put back on treatment through home visits by health staff or community health workers.
• Action is needed within a day of the missed treatment during the intensive phase.
• Action is needed within a week of the missed treatment during the continuation phase.
• Reasons for treatment interruption must be recorded.

Patient Flow for DOT

• After receiving sputum results, the medical officer (MO) of the Peripheral Health Institution (PHI) Is responsible for:
  • Establishing the diagnosis of tuberculosis.
  • Deciding the type of patient and category of treatment
  • Explaining the disease, treatment (dosage, schedule, duration, side effects, and prevention), the need for contact examination, progress monitoring frequency until cure and importance of directly observed treatment (DOT).
  • Determining the DOT center and DOT provider
  • Initiating the Tuberculosis Treatment Card (in duplicate when required) and the TB Identity Card
  • Making the patient-wise box available at the DOT Centre along with the TB treatment Card, TB Identity Card and sputum containers for morning samples of follow-up sputum examinations.

Follow-up Smear Examinations

New smear-positive patients

• Two smears are examined each time during follow-up.
• The first follow-up sputum examination is done at the end of 2 months of intensive phase.
• On the 22nd dose in intensive phase, the patient is given a sputum container and instructed to bring the early morning sample.
• The patient brings the sputum sample when he comes for the 23rd dose in the intensive phase when a spot sample is also collected.
• The results of both the smear examinations will be available at the next visit of the patient.
• If both smears are negative, the patient will be put on the continuation phase.
• If either of the smears is positive, the intensive phase will be extended by one more month, and sputum examination I will be repeated at the end of the third month.
• Thereafter, the patient is put on the continuation phase regardless of his/her sputum status at the end of the extended intensive phase.
• Subsequent follow-up smear examinations are done after 2 months into continuation phase and if found positive the patient is declared as a treatment fallure, re-registered and started on the re-treatment regimen afresh.
• If the follow-up sputum is negative, the continuation phase is completed and smear examination repeated at the end of treatment.
• The sputum should geneally be collected at the time of collection of the 16th blister so that the results are available at the time of supply of the last week's blister pack.
• Results of end of treatment sputum should be available not later than one week of completion of treatment.

Re-treatment patients

• The first sputum smear examination is done at 3 months after beginning of the intensive phase.
• On the 34th dose of the intensive phase the patient is given a sputum container and instructed to bring the early morning sample.
• The patient brings the sputum sample when he comes for 35th dose in the intensive phase when a spot sample is also collected.
• The results of both the smear examinations will be available at the next visit of the patient.
• If both smears are negative, the patient will be put on the continuation phase.
• If either of the samples is positive, the intensive phase of treatment will be extended by one more month, and another smear examination will be done at the end of the fourth month of treatment.
• Thereafter, the patient is put on the continuation phase regardless of his sputum status at the end of 4 months of the intensive phase.
• Subsequent follow-up sputum examinations are done after 2 months into continuation phase.
• Irrespective of the results of the follow-up smear examination, the patient continues and completes the treatment when a final follow-up sputum smear is done.
• The sputum should generally be collected at the time of collection of the 20th blister so that the results are available at the time of supply of the last week's blister pack.

Smear-negative patients

• Two smears are examined during the follow-up visit at the end of 2 months of the intensive phase and again at the end of treatment.
• If the patient becomes sputum smear-positive at the end of IP or at the end of treatment, his outcome is failure' and is started on re-treatment Cat II regimen after registration.

Treatment Outcome

• The patient's treatment outcome is identified by reviewing her/his Tuberculosis Treatment Card.
• The treatment outcome and the date the patient stopped treatment is written in the appropriate column in the Tuberculosis treatment card.
• The date on which the patient stopped treatment is the date of the last dose of drugs taken.

Determination of Treatment Outcome

• Cured: Registered as pulmonary smear-positive, completed treatment, and had negative smear results on 2 occasions, one of which is at the end of treatment.
• Treatment completed: Registered as pulmonary smear-positive, completed treatment with negative smear at the end of the intensive phase but none at the end of treatment.
• Died: Was to know to have died from any cause whatsoever while in treatment.
• Failure: Registered as pulmonary smear-positive CAT I and was smear-positive at 5 months or later or If patient was registered as pulmonary smear-positive CAT II (retreatment), and was smear-positive at five months or later of CAT II treatment
• Defaulted: Has not taken drugs for more than 2 months consecutively anytime after starting treatment.
• Transferred out: Was transferred to another TU/district, and his/her treatment outcome is not available