Tuberculosis

2nd most common cause of death by infection

Organisms

1.M.tuberculosis

2.M.bovis(Reservoir is cattle/cow milk)

3.M.africanum(Reservoir is human)

Pathogenesis

1.Primary disease(Children type)

Inhalation>Alveoli>Recruits macrophage>Transformed into  epithelioid cell ,Langhan's cell>Aggregates with lymphocyte>Forms granuloma>Granuloma aggregates and forms initial lesion called Gohn focus>Gohn focus with regional lymphadenopathy is called Gohn complex/primary complex of ranke

Primary diseases affects middle and lower zone

Seconndary focus-Node/common ,serous membrane(pleura,pericardium ,peritoneum) ,meninges ,bones ,liver

Mediastinal node>Spread>Supraclavicular node(Clinical)

Tubercular node-Painless ,initially mobile ,matted , discharge/Collar stud formation

2.Post primary(Adult type)

Exogenous(New infection) or endogenous type(Reactivation of  primary TB)

Affects apical portion of upper lobes

May causes bronchogenic spread ,called satellite lesion

Clinically lung TB is post primary

Gohn focus-It is pale , caseous nodule ,few mm to 2 cm diameter situated at the periphery of lung

How TB causes collapse

          More common in children when lymphoma is associated

          In adult when endobrocnhiolar TB is associated

Miliary TB - Blood-borne dissemination gives rise to miliary TB, which may present acutely but more frequently is characterised by 2–3 weeks of fever, night sweats, anorexia, weight loss and a dry cough.

Differential diagnosis of miliary TB-Sarcoidosis ,pneumoconiosis/asbestosis ,pulmonary eosinophilia ,hemosiderosis ,carcinomatosis

Post tussive crepitation-Crepitation appears after cough ,indicated TB

How a pulmonary TB Presents

1.Chronic cough > 3 weeks , often with haemoptysis

2.Pyrexia of unknown origin

3.Unresolved pneumonia

4.Exudative pleural effusion

5.Asymptomatic (diagnosis on chest X-ray)

6.Weight loss, general debility

7.Spontaneous pneumothorax

Investigation

CBC-Lymphocytosis ,high ESR

Chest X ray-Patchy opacity

Sputum for AFB-On the spot >Next day, early morning sample to be brought from home>On the spot during receiving home sample

Gene X pert(NA amplification test)-Sputum and node biopsy>If RPO gene is found ,it is Rifampicin resistant.Result within 1 day

Pleural fluid cytology-

              Physical-Normally amber colour

              Biochemical-Exudative(Protein >30g/dl)

Treatment

Category-1(6 months regimen for new onset pulmonary/extra pulmonary TB)

1st line

2HRZE/Initial or intensive phase-Reduce population

4HR/Continual phase-Kills remainders

                        
                                   [TB meninges/pott's-12 months; 2HRZS ,10HR ]

2nd line-(For resistant TB)

Kanamycin

Amikacin

Ciprofloxacin

Category-2(When Category-1 fails ,when -ve sputum become positive; 2 weeks)//8 months

2HRZES

1HRZE

5HR

Patient become non infective after 2 weeks of treatment

Follow up(How will you asses treatment is working/not)

Clinical S/S- S/S dissapears ,no fever ,weight gain ,reduced cough

Examination-No crepitations

Investigation-

            CBC

            ESR decreased

            Sputum -ve

                  Category-1(2nd ,5th ,6th months)

•   Why not before 2 months?-Maximum drug action needs 2 months>If still +ve sputum>advise to take drug further 1 months>If still sputum +ve>do gene Xpert

                  Category-2(3th ,5th ,8th  months)

             X ray chest

When will you know a treatment failure

+ve sputum at 5 months

MDR TB

What is MDR TB

+ve sputum after  2 months Rx OR , resistance to R/H with/without other DR

What is DR TB

Resistance to any 1st line drug

What is XDR TB

Resistance to R/H with any quinolones with 1 injectable 2nd line drug

Doses of TB drugs

                  H(Isoniazide/INH)=5-10mg/kg

                  R(Rifampicin)=10mg/kg

                  Z(Pyrazinamide)=20-35mg/kg

                  E(Ethambutol)=15-25mg/kg

                  S(Streptomycin)=0.7 or 1g/kg

                  Single dose in morning in empty stomach

                  If can't tolerate ,give in  full stomach

                  Ceftriaxone 2g BD injection in TB meningitis

Side effects of TB drugs

Rifampicin

1.Discoloration of body secretion(e.g. orange urine)

2.Skin rash

3.Hepatitis

INH

1.Peripheral neuropathy-Tingling sensation ,numbness of limb(So add  vitamin B6)

2.Skin rash

3.Hepatitis

Pyrazinamide

1.Hyperuricemia

2.Gout(Joint pain)

3.Hepatitis

Ethambutol

Retrobulbar neuritis

Streptomycin

1.Nephrotoxicity

2.Ototoxicity

Advice after Rx

1.ওষধ নিওমিত খাবেন

2.ওষধ খেলে পেসাব কম্লা রঙের হবে ,এতে ঘাবড়ানোর কিছু নেই

3.পেসাব ও চোখের রঙ হলুদ(Hepatitis) ওষধ বন্ধ করে ডাক্তারের কাছে যাবে

4. ২ মাশ  নিচের test গুল করতে হবে-

         Sputum for AFB

                      CBC ,chest X ray

5.Use barrier method along with OCP(Contraceptive failure with Rifampicin)

If Hepatitis occurs during treatment course, what to do?Stop drug>Sign-symptoms dissapear>Do Liver function test>If course gap is more than 1 month start treatment as new onset TB and if gap is less than 1 month ,then  fillup those days

What is DOTS

Directly observed treatment short course-Drugs taken in presence of an attendance 3 times weekly[For prevention of resistance]

What is FDC

Fixed drug combination-Rimstar 4 FDC (HRZE)     

Question.50 years old male with fever for 2 weeks ,with walking difficulty for 10 days,associated with paraplegia.

Diagnosis-Spine TB(If gibbus->Pott's disease)

Here Disc space reduced-In TB

but disc space is normal in Secondary carcinoma from prostate

Prevention

BCG vaccine/Bacillus Calmette Guerin ,a live attenuated vaccine from M.bovis

Intradermal vaccine

It prevents dissemination including TB meningitis

MT test

          10 TU used ,given intracutaneously ,reading is taken upto 2-4 days

          It is supportive evidence of diagnosis of TB

          In suspected case of sarcoidosis

          CD4 is responsible for +ve test

          If smear  +ve -No need for MT

          Induration >10mm is +ve test(BCG ,recent/past infection)

          Induration >15mm is strongly +ve

          False -ve in extreme age ,cytotoxic drugs ,immunosuppression ,sarcoidosis ,lymphoma

          False +ve in BCG(>5mm) ,non tubercular mycobacterium

Indication of steroid in TB

1.Adrenal TB

2.TB of serous cavity

                              Pericarditis

                              Pleural effusion

                              Ascitis

3.Tubercular meningitis

4.Occular TB

5.Genitourinary TB