Tuberculosis
Tuberculosis is a disease caused by Mycobacterium tuberculosis along with M. africanum (which
causes an identical picture to TB).
TB can be difficult to diagnose and can cause a great many different pathologies depending on its
location in the body. An new epidemic of TB has occurred in Africa in recent years due to the
increased prevalence of HIV which makes TB bacteria more likely to cause disease and be passed on.
Only 10% of healthy people infected with TB develop disease but this is much higher in the below
risk groups…
 HIV infected individuals and others immunosuppressed (chemotherapy, steroids)
 Recent TB infection that has been treated increases the risk of further infection
 Elderly and new born babies with tired and developing immune systems
 Malnutrition including vitamin D deficiency
 Diabetes mellitus
 Any chronic lung disease
 Other infections (measles, visceral leishmaniasis)
 Alcohol excess
 Smoking
 Poverty
Clinical features
The classical symptoms are fevers, night sweats, weight loss, anorexia, malaise and productive cough
maybe with blood(haemoptysis). The symptoms come on slowly over more than three weeks and it
is vitally important to get a history of the duration of illness. TB patients can often present with
several months of symptoms. If the ~TB is elsewhere in the body and not in the lungs then no cough
will be present.
TB can occur anywhere in the body, if a patient has persistent swellings or pus it is advisable to take
a sample and send it to the lab for pus. TB should be thought of if a wound doesn’t heal or a patient
continues to deteriorate/ not improve with normal antibiotic therapies.
Common TB locations
Pulmonary TB
This is the infective form of TB, the patient commonly but not always has a cough with or without
haemoptysis for over three weeks. Chest examination may demonstrate an area of crackles,
bronchial breathing or effusion.
Diagnosis of pulmonary TB should start with examination of the sputum for AAFBs which are taken
early in the morning when the patient wakes up and sent immediately to the lab. These will only be
positive in 65% of non HIV positive patients and less in those with TB.
Provided by T. Whitfield 2012
If effusion is present it should be tapped to reveal an exudate (>30g/dL, or >50% blood plasma) with
a lymphocyte predominance, it is rare that any AAFB will be found in the fluid.
Chest x-ray can also indicate the presence of TB
This x-ray has apical consolidation with some caviatation this could be TB, malignancy or pneumonia.
A history suggestive of TB could help your diagnosis.
This x-ray shows nodules throughout the lung fields which is suggestive of millary TB which often is
sputum negative.
Provided by T. Whitfield 2012
This x-ray shows two large areas of consolidation in the middle to upper lung fields, there is also a
pneumothorax on the right side of the lung. This is likely TB if the patient has a suggestive history. If
this was pneumonia the patient would be very ill.
This x-ray shows bihilar lymphadenopathy which is common in TB, sarcoid and lymphoma. Look fro
lymph nodes elsewhere and biopsy them.
Provided by T. Whitfield 2012
This x-ray shows a left sided pleural effusion which is very common in TB, it is important to tap to
look at the cell count. TB will show an exudate with lymphocyte predominance.
TB lymphadenitis
This is swelling of from one lymph node to all nodes in the body. They may initially be rubbery but
then later can be fluid filled (fluctuant) and may even discharge pus. They are usually painless and
present for several months. Often they will enlarge during TB therapy.
The best way to diagnose TB adenistis is to aspirate the node with a needle and send it to the lab to
look for AAFB (alcohol and acid fast bacilli). This is more commonly positive in HIV positive patients
than non HIV positive patients.
Bone TB
The most common site is in the spine and at its worst can cause acute spinal chord compression of
the lower limbs( depending on the level of involvement but almost always lower limbs and bowel
and urinary incontinence). A swelling seen on the back due to the TB there is called a glibus and
when found is virtually diagnostic of TB.
x-ray will show collapse of the vertebral disc.
If an acute specialised orthopaedic team is not available to decompress acute cord compression then
the treatment is bed rest and antiTB therapy.
TB meningitis
Provided by T. Whitfield 2012
This has the similar presentation of neck stiffness, headache, photophobia, seizures, cranial nerve
palsies, confusion and decreased GCS as meningitis but tends to come on over a much slower period
than bacterial meningitis i.e not over 24-48 hours.
Lumbar puncture should be performed which rarely shows AAFB but TB is indicated as below…
Bacterial
Appearance
TB
Viral
Cloudy
Clear mostly
Clear
WCC/mm
90-1000+
10-1000
50-1000
Type wcc
Polymorph
Lymphocyte
Lymphocyte
Glucose
<1/2 blood
<1/2 blood
>1/2 plasma
Protein
>1.5
1-5
<1
Organisms
Seen
Rarely seen
Not seen
3
The diagnosis is often made on a best guess basis of clinical history, signs and results of
investigations.
Prednisolone at a dose of 1mg/kg every 24 hours is added to the treatment of TB meningitis to
reduce the swelling and improve the patients prognosis. This is continued for a least a week and
titrated down by 5mg every other day, suddenly stopping long term steroid can be fatal.
Abdominal TB
TB can reside anywhere in the intestine the most common site being the terminal ileum. Symptoms
include diarrhoea, weight loss, abdominal pain and fever. This can only really be diagnosed through
biopsy of the effected area in surgery and endoscopy, it often looks very similar to chrons disease.
TB can also be found in ascetic fluid with the same lymphocyte predominance and high protein
content as seen on a pleural effusion.
Pericardial TB
This is more common in HIV patients and is suspected when a large globular heart is seen on the xray. The pericardial effusion can cause features of tamponade (soft heart sounds, raised distended
JVP). Effusion can be confirmed and tapped to analyse the fluid which will be an exudate with raised
lymphocytes.
Genitourinary TB
TB can locate anywhere in the genitourinary tract it typically presents with dysuria, haematuria,
fever and loin mass/ pain. It can also localise to the testicles in males. Diagnosis is often on biopsy,
though persistant raised white cells in the absence of any bacteria is a strong indicator of TB.
Provided by T. Whitfield 2012
Diagnosis
Sputum
Finding AAFB in the sputum will confirm TB, to do this send 3 samples, ideally one on presentation,
one early morning and one on the next clinic visit. Often in Malawi three early morning samples are
taken. As mentioned previously negative sputum does not exclude pulmonary TB and samples are
less likely to be positive in HIV patients.
Diagnosing smear negative TB
In a smear negative patient a chest x-ray will aid diagnosis as shown above.
An antibiotic trail on a patient who is smear negative and with a cough will show limited
improvement in a TB patient.
The differential diagnosis of smear negative TB is as follows…
 Pneumonia
 Asthma
 Other HIV related lung disorder
 Lung abcess
 Lung Cancer
Tubercullin skin testing is not widely used in Malawi and is not fully diagnostic of TB but can be
useful in aiding diagnosis.
Treatment
TB can be treated well preventing spread and curing the patient. The Treatment has to involve a
combination of drugs (at least two) to avoid resistance developing. Treatment should last 6-8months
and is often monitored in Directly Observed Treatments (DOTs) to ensure compliance this can be
done by any society member.
Halting treatment part way though can lead to antibiotic resistance developing which can make it
much more difficult to treat.
TB is treated by the following drugs either as part of a once daily or three times weekly regime
Isoniazid (INH,H) OD = 5mg/kg, 3x per week= 10mg/kg
Has the side effect of hepatotoxicity and peripheral neuropathy.
Rifampicin (R) OD 10mg/kg, 3x per week= 10mg/kg
Most regularly used in regimes. It interacts with warfarin, anti-epileptics and oral contraceptives
(should be switched) . It can cause hepatotoxicity but is less likely than the others.
Pyrazinamide (Z)OD =25mg/kg, 3x per week=35mg/kg
Usually used in first 2 months of therapy. Is the most hepatotoxic of 1st line TB drugs.
Provided by T. Whitfield 2012
Ethambutol(E) OD =15mg/kg, 3x per week=30mg/kg
Prevents resistance to other TB drugs. Has the side effect of ocular toxicity, vision is checked before
starting and is any loss of colour vision or vision deterioration.
Streptomycin (S) OD =15mg/kg, 3x per week=15mg/kg
2nd line Tb agent. Has the side effect of ototoxcity (mainly vertigo) and renal dysfunction. It cannot
be used in pregnancy whilst other TB drugs can.
The first line regime is usually 2 months of isoniazid, rifampicin, pyrinamide and ethambutol,
followed by 2 months of isoniazid and rifampicin.
Alternate 1st line regime is 2 months of isoniazid, rifampicin, pyrinamide and ethambutol, followed
by 6 months of isoniazid and rifampicin.
Any signs of the side effects (hepatotoxicity, visual deterioration) should lead to the immediate
stopping of the TB medications and they are only to be restarted when the condition is improved
and specialist advice sought out.
Provided by T. Whitfield 2012