Diagnosis of tuberculosis can be made by following methods:
- Clinical
- Laboratory
- Radiological
- Histopathological
All are explained in detail in the following pdf.
See also: Tuberculosis of the Hip Joint
See also: Spinal tuberculosis (Pott’s Spine)
See also: Tuberculosis of the elbow joint
Diagnosis of TB
Diagnosis
Clinical Presentation And Medical History
Physical Examination
Radiology
Laboratory Methods
laBORATORY mETHODS
CONVENTIONAL
Sample Collection
Microscopy
Culture
Biochemical tests
Tuberculin Skin test(TST) / mantoux test
IFN-Y release assay(IRGA)
Nucleic Acid amplification test(NAAT)
BACTEC M-GIT 960 system
Serology(36%)
RAPID TESTING
- Sample Collection Specimen types:
Pulmonary Specimen
–Sputum
-Gastric lavage
-Transtracheal aspirations
-Bronchoscopy
-Laryngeal swabbing
Urinary Specimen
Tissue and body fluid
Blood specimens
Wounds, skin lesions, and aspirates
●
SPUTUM COLLECTION: 3 EARLY MORNING
SAMPLE OF 3 CONSECUTIVE DAYS
URINE COLLECTION: 3 CONSECUTIVE
MORNING SAMPLE OF URINE
2. Microscopy:
Sensitivity ≥ 10,000 bacilli per ml of sputum.
Most uncomplicated and most rapid procedure.
ZN staining(Ziehn-Nelson stain):
Smear >hot carbol fuschin (5-7 min) >> wash and decolorize with 20% H2SO4 +95% ethanol for 2 mins >> counter stain with methylene blue or malachite green >> mb seen in bright red and background as per counter stain used
NOTE: less sensitive more specific
Requires more time
Auramine-rhodamine stain
Stain with Phenotic auramine rhodamine stain >> decolorize same >> counter stain with KMNO4 >> mb fluoresces bright yellow against a dark background.
Note: more sensitive, less specific
requires less time
useful for several smears done daily
4. Culture
Culture Characteristics
`Aerobes, grows slowly (12-24 hr)
`Colonies usually appears in 2-3 wks and may require up to 8 wks
`Opt. temp : 37°
`pH: 6.4-7.0
`Colony characteristics: dry rough, raised irregular,buff and cream color
5.Biochemical tests
qNiacin test: +ve for M.tb and –ve with bovine type of bacilli
qAryl sulphate test: +ve with atypical Mb
qNitrate Reduction test: +ve for M.tb
qCatalase peroxidase test: differentiate tubercle bacilli from atypical
q
Catalase peroxidase activity is lost when tb bacilli become INH resistent , so it is also the indication for the sensitivity to INH.
raPID tESTING
Tuberculin test (Mantoux test)
Tuberculin is a glycerol extract of the tubercle bacillus.
A standard dose of 5 tuberculin units (0.1 mL) is injected intradermally and read 48 to 72 hours later. This intradermal injection is termed the Mantoux technique. A person exposed to the bacteria is expected to mount an immune response in the skin containing the bacterial proteins.
Classification Of tuberculin Reaction:
False Positive: Infection to atypical Mb or pre-exposed or immunized.
False Negative: Immuno suppressed, malnutrition
Interferon Gamma Release Assay(IRGA):
measure the cell-mediated response in infected individuals through the levels of interferon-gamma released.
T cell release IFN-gamma by the stimulation of highly tubercular specific antigens ESAT-6 and CSF-10.
Diagnose active as well as latent TB infection.
Nucliec Acid Amplification Test(NAAT)
Use PCR for the diagnosis of Mb
capable of carrying out drug susceptibility testing (DST) for 1st line TB drugs.
GeneXpert technique is used nowadays for MIB and RIF (prinp.)
BACTEC MGIT 960 system
Middlebrook 7H9 as media
Widely used.
greater capacity, safe operation,
fast results and the highest throughput
of any automated system-the world’s
first automated system for high-
volume
mycobacteria growth, detection and
susceptibility testing!
Permits highly accurate detection of O2 consumption by Mb by the use of advanced fluorometric technology.
Radiology
X-ray
CT Scan
MRI
Ultrasonography
Biopsy
Types of vertebral TB
1.Paradiscal
2.Central
3.Anterior
4.Posterior
X-RAY FINDINGS
PARADISCAL TYPE OF LESION (commonest)
Narrowing of the disc space is the earliest finding
Paravertebral shadows are produced by the extension of tuberculous granulation tissue and the collection of abscess in the paravertebral region
The wedge-shaped collapse of the vertebral body leading to kyphotic deformity
X-RAY FINDINGS
CENTRAL TYPE OF LESION
The vertebral body loses the normal bony trabeculae and may show areas of bone destruction
In later stages- concentric or concertina collapse
The decrease in disc space is minimal
Paravertebral shadow is usually not marked.
X-RAY FINDINGS
ANTERIOR TYPE OF LESION
Erosion seen anteriorly in vertebral body on lateral view
Decrease in disc space occurs late and is minimal
X RAY FINDINGS
APPENDICIAL TYPE OF LESION (rarest)
Identified by erosive lesion, intact disc spaces paravertebral shadows
CT/ MRI best to diagnose this type of lesion.
Appendicial type
CT SCAN
Identifies paravertebral soft tissue more readily than X rays
Better evaluation of pathological progress
To evaluate clinical progress
MRI
Detect cord compression
Useful in posterior spinal elements, craniovertebral and cranio dorsal region, sacrum and sacroilium region.
USG
Detect cold abscess in lumbar disease
BIOPSY
Percutaneous CT-guided biopsy and culture of the organism
Pott’s paraplegia
Classification:
2 main groups (Griffiths, Seddon, and Roaf 1956) in the pre-anti-tubercular era.
Group A Early Onset Paraplegia
Active phase
First 2 years
The underlying pathology is most commonly inflammatory
Also called: paraplegia associated with active disease
Group B Late Onset Paraplegia
More than 2 years
Due to recrudences of the disease or mechanical cause
Paraplegia associated with healed disease
Clinical Features:
Clonus is the first and most prominent early sign
Sense of Position and vibration is last to disappear.
TREATMENT OF SPINAL TUBERCULOSIS
Definitive diagnosis by biopsy and culture is necessary before starting the treatment, because of the toxicity of the chemotherapeutic regimen and the length of treatment required.
In developing countries where TB is endemic and resource is scarce, a typical clinical and radiological appearance may be sufficient to start treatment without biopsy.
TREATMENT
Conservative: when the disease is not advanced or when facilities and expertise for radical spinal surgery is not available.
1.Ambulant chemotherapy for 18 months for early or limited disease
Drugs
•HRZE for 3 months
•HRE for another 15 months
2. Improve the general nutrition of the patient.
3. Continuous bed rest and chemotherapy when the disease is advanced but where there are no facilities for radical spinal surgery provided there are no absolute indications for surgery.
TREATMENT
Immobilization was done to
To provide rest
To provide stability
4. Gradual mobilization of the patient in the absence of neural deficit with the help of a suitable spinal brace as soon as the comfort of the patient permits. The spinal brace is continued for 6-12 months. (12-24mths if operated)
Nepal orthopedic association NOA (2005 AD)
Middle Path Regime
Tuli and Kumar advocated triple drug therapy without surgery.
Absolute Indications for surgery
- Paraplegia occurring during usual conservative treatment.
2. Paraplegia getting worse or remaining stationary despite adequate conservative treatment.
3. Severe paraplegia with rapid onset may indicate severe pressure from a mechanical accident or abscess.
4. Any severe paraplegia such as paraplegia in flexion, motor or sensory loss for more than six months, complete loss of motor power for one month despite adequate conservative treatment.
5. Paraplegia is accompanied by uncontrolled spasticity of such severity that reasonable rest and immobilization are impossible.
SURGERIES PERFORMED
Evacuation of pus or Debridement
Cervical spine
Retropharyngeal abscess
Abscess in post triangle of the neck
Dorsal spine
Costotransversectomy
Anterolateral decompression
Lumbar spine
Paravertebral abscess
Psoas abscess
Surgery
Radical surgery:
Excision of all infected and necrotic material
Gap filled with bone graft e.g. rib, fibula
Anterior or posterior fusion
Anterior or posterior fixation
