Tuberculosis Flashcards
Tuberculosis
Tuberculosis
TB is an infectious disease caused by several species of mycobacteria (M). The most common types in West Africa are M. tuberculosis, M. africanum, M. ulcerans (cause of Buruli ulcer)
M. Tuberculosis & africanum are the ones that cause pulmonary TB and it is transmitted from person to person through droplet infection (coughing, sneezing, spitting)
Case Identification(Suspecting tb)
A. Pulmonary TB in an adult
• Persistent cough of 2weeks or more
•Score of 4 or more on symptom screen.
Symptom Screen
symptom / no /. yes
Cough for >2weeks 0 2
Coughing up blood 0 2
•Sputum production 0 2
•Loss of wt in last 3months 0 1
•Drenching night sweats 0 1
•Fever 0 1
•Chest pain 0 1
•Cough < 2 weeks 0 1
•History of contact with tb case 0 1
•History of smoking /alcohol 0 1
Total 4 or more suspect tb
Cough < 2wks plus
-Blood stained sputum
-Fever usually at night
-Weight lost
-History of previous tb in patient or close contact/family member
Consider eligible for testing if :
•Cough is for 2 weeks or more
•Cough < 2weeks and score on symptom screen 3 or more
•Score 4 or more on symptom screen
•Cough 24hrs or more in HIV positive person
B. Extra-pulmonary TB- may have the following symptoms:
•Weight loss, fever, night sweats.
•Plus symptoms depending on the organ affected eg joint pain & swelling in TB of the joint.
Childhood TB
Scoring system for suspected tb— view slides
A score of 7 or more indicates a high risk of tb.
Example
Feature Score
Wt for age 1
Family history 3
Mantoux test 0
Unexplained fever 2
Lymph node 3
Total Score 9
This is suggestive of tb infection and needs further investigations
Childhood TB- It is difficult in diagnosing TB in children. Diagnosis depend on consistent clinical features & investigations
•History of contact (living in same household or in frequent contact with a source case with pulm. Tb)
•Failure to thrive
•Clinical examination
•Chest x-ray
•Tuberculin (mantoux) test may be helpful
A negative tuberculin test (induration <10mm diameter) does not exclude TB. The following may suppress it in a person with active TB: HIV, malnutrition, cancer, severe bacterial infection, viral infection (measles, chickenpox).
A positive tuberculin test (induration>10mm in a child who has no BCG and >15mm in a child who has BCG.
A positive tuberculin test is the only one piece of evidence in favor of the diagnosis of TB in a child
Investigations
Investigation of TB
A.Sputum examination- whenever possible 2 sputum specimen should be collected within 24hrs- 1 spot and 1 the following morning. If 2 specimen can be collected the same day it should be 1 hour apart-
•1st specimen on the spot
•2nd specimen 1 hour after the 1st specimen
If at least 1 sample is positive treat for tb
When to do Sputum Examination
•At 2nd month after starting treatment
•Repeat at 3rd month if results at 2nd month +ve
•At 5th month
•At 6th month
B. Chest x-ray
Is done for all suspected sputum smear negative tb.
C. New laboratory diagnostic Methods
•Molecular testing- Gene Xpert technique- for detecting tb and rifampicin resistance using DNA technology. The 1st point of diagnosis now(since 2017) is gene Xpert. If challenges go back to sputum examination.
-Solid culture
-Liquid culture
•Tuberculin testing- it has a role in diagnosing tb in children
•Do culture and DST and /or Gene Xpert for all cat 2 cases(since 2017) to see if rifampicin resistant or rifampicin and isoniazid resistant .
•Newer test- Line Probe Assay(LPA)
Interpreting Results
•If 1 or both sputum samples are +ve the patient is smear +ve tb
•Clinically ill smear negatives, relapses, return after default, treatment failures may need request for sputum Gene Xpert, sputum culture and DST and a decision is taken
•HIV +ve with smear –ve smears and observed abnormalities in chest x-ray should be treated as tb
•If no chest x-ray abnormalities in HIV +ve patient then you do sputum Gene Xpert
•If sputum Gene Xpert is +ve and there is no resistance to rifampicin (DST) then register as smear –ve PTB
•If sputum Gene Xpert is +ve and there is resistance to rifampicin then send sputum for culture and DST and refer patient to clinician trained in MDR TB treatment
Case Definitions
•Smear positive TB-at least 1 sputum smear trace or positive for TB
•Smear negative TB-at least 2 sputum negative for TB
•Extra pulmonary TB- TB outside the lungs
•Relapse-a TB patient who previously received treatment and was cured but has once again developed smear positive TB
•Treatment failure-a smear positive case who remain or became smear positive 5months or longer after starting treatment
•Treatment defaulter(lost to follow-up)-a new TB patient who completed at least 1 month of treatment and returned 2 months or more interruption of treatment
•New case-a patient who has never had treatment for TB or taken treatment <1 month
Essential diagnosis
Essentials of Diagnosis
•Malaise, anorexia, weight loss, productive cough, night sweats, hemoptysis
•Apical crackles of lungs
•Positive sputum/GeneXpert, positive tuberculin skin test especially recent change from negative to positive
•Apical infiltrates of chest x-ray, often with cavities
Treatment of TB
Treatment of TB
First of all you have to decide the treatment category. TB treatment is categorised into four:
•Category 1(New)- All new cases (new smear +ve, new smear –ve, extra-pulmonary)
•Category 2(Previously treated)- previously treated smear +ve cases, relapse, treatment failure, treatment after interruption
•Category 3-children under 15 years.
•Category 4- MDR TB
Category 1 (First line treatment)
Duration of treatment- 6months
Comprises -initial phase of 2 months (56 days) & continuation phase of 4months (112days).
Drug regimen-initial phase-HRZE(PM) as 1 caps
continuation phase-HR as pill H- isoniazid 75mg, R- rifampicin 150mg, Z-pyrazinamide 400mg, E-ethambutol 275mg, S-streptomycin injection
INITIAL PHASE
CONTINUATION PHASE
WEIGHT IN KG
(HRZE)2
(HR)4
30-39
2
2
40-54
3
3
55+
4
4
Category 2 (Currently, since 2017 category 2 has been discontinued in Ghana upon the recommendation of WHO
Cat II tb regimen has been discontinued in Ghana(since 2017) upon the recommendation of WHO. It has been proven that it has no benefits for patients failing first line tb treatment.
All the patients eligible for Cat II shall undergo culture and Drug Sensitivity Testing (DST) and/or GeneXpert to evaluate for drug resistance.
Based on the DST or GeneXpert result the standard first line tb treatment (2HRZE, 4HR) shall be initiated if no resistance to rifampicin is detected. If resistance to rifampicin or rifampicin and isoniazid is detected the patient shall be put on drug resistant tb treatment regimen- refer to tb Clinician
Category 3(<15 years)
New: Initial Phase
<15 YEARS
New: Continuation Phase
Slides
NB: TB meningitis and osteo-articular TB treatment is:
2HRZE + 10HR
All patients on Isoniazid should take 25mg of pyridoxine(vit B6) to prevent peripheral neuropathy
Category IV- Drug Resistant Tuberculosis(DR-TB)
•Is suspected in a person who remain bacteriologically positive after intensive phase of standard first line TB treatment with/without clinical improvement
Causes of Drug Resistant TB
•From a microbiological perspective, resistance is caused by a genetic mutation that makes a drug ineffective against the mutant bacilli.
•From a clinical and programmatic perspective however, it is an inadequate or poorly administered treatment that allows for selection of a drug-resistant strain to become the dominant strain in a patient infected with TB.
