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21. Brudey K, Driscoll JR, Rigouts L, Prodinger WM, Gori A, Al-Hajoj SA, etal. Mycobacterium
tuberculosis complex genetic diversity: mining the fourth international spoligotyping database (SpolDB4) for classication, population genetics and epidemiology. BMC Microbiol.
2006;6:23.
22. Singh A, Gopinath K, Sharma P, Bisht D, Sharma P, Singh N, et al. Comparative proteomic
analysis of sequential isolates of Mycobacterium tuberculosis from a patient with pulmonary tuberculosis turning from drug sensitive to multidrug resistant. Indian J Med Res.
2015;141(1):27–45.
23. Rufai SB, Kumar P, Singh A, Prajapati S, Balooni V, Singh S.Comparison of Xpert MTB/RIF
with line probe assay for detection of rifampin-monoresistant Mycobacterium tuberculosis. J
Clin Microbiol. 2014;52(6):1846–52.
24. Bomanji JB, Gupta N, Gulati P, Das CJ.Imaging in tuberculosis. Cold Spring Harb Perspect
Med. 2015;5(6):a017814.
25. Kumar P, Pandya D, Singh N, Behera D, Aggarwal P, Singh S.Loop-mediated isothermal amplication assay for rapid and sensitive diagnosis of tuberculosis. J Infect. 2014;69(6):607–15.
26. Sankar MM, Kumar P, Munawwar A, Kumar M, Singh J, Singh A, et al. Usefulness of multiplex PCR in the diagnosis of genital tuberculosis in females with infertility. Eur J Clin
Microbiol Infect Dis. 2013;32(3):399–405.
27. Singh S, Singh J, Kumar S, Gopinath K, Balooni V, Singh N, etal. Poor performance of serological tests in the diagnosis of pulmonary tuberculosis: evidence from a contact tracing eld
study. PLoS One. 2012;7(7):e40213.
28. Patel VB, Singh R, Connolly C, Kasprowicz V, Zumla A, Ndungu T, etal. Comparison of a
clinical prediction rule and a LAM antigen-detection assay for the rapid diagnosis of TBM in
a high HIV prevalence setting. PLoS One. 2010;5(12):e15664.
29. Schepers K, Mouchet F, Dirix V, De Schutter I, Jotzo K, Verscheure V, etal. Long-incubationtime gamma interferon release assays in response to puried protein derivative, ESAT-6, and/
or CFP-10 for the diagnosis of Mycobacterium tuberculosis infection in children. Clin Vaccine
Immunol. 2013;21(2):111–8.
30. Gupta AK, Singh A, Singh S. Diagnosis of tuberculosis: nanodiagnostics approaches. In:
NanoBioMedicine [Internet]. Springer; 2019 [cited 2023 May 5]. p. 261–83. https://www.
ncbi.nlm.nih.gov/pmc/articles/PMC7122355/
31. Laksanasopin T, Guo TW, Nayak S, Sridhara AA, Xie S, Olowookere OO, etal. A smartphone dongle for diagnosis of infectious diseases at the point of care. Sci Transl Med.
2015;7(273):273re1.
32. Gupta AK, Srivastava S, Singh A, Singh S.Development of rapid immuno-diagnostic test for
the early detection of tuberculosis. Int J Mycobacteriol. 2016;5(Suppl 1):S114–5.
A. Singh etal.
Chapter 2
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Clinical andRadiological Diagnosis
ofTuberculosis
AmberKumar andBhavnaDhingra
Abstract Accurate and timely diagnosis of tuberculosis (TB), including drug sen-
sitivity patterns, is essential for the patient’s health and the population in contact
with them. In the diagnosis of tuberculosis, strong clinical suspicion required in
populations having constitutional symptoms is dened as:
• Persistent unexplained fever documented ≥2weeks and/or
• Unremitting cough ≥2weeks and/or
• Unexplained documented loss of weight >5% in the last 3 months despite ade-
quate nutrition
The diagnosis of TB is based on the isolation of pathogens. Paucibacillary cases
and inaccessible sites of infection are the limitations in isolating mycobacteria.
Although tuberculosis can affect any organ, the lung remains the most commonly
involved organ. Recently, the World Health Organization (WHO) has replaced the
term smear-negative TB with clinically diagnosed TB.Often, tuberculosis is rst
suggested by an imaging study, especially in inaccessible sites. An upfront chest
X-ray (CXR) is recommended in all suspected cases of pulmonary tuberculosis. In
the era of universal drug sensitivity testing, all suspected cases of tuberculosis based
on clinical or radiological ndings must be submitted for microbiological conrmation, at least for rifampicin and isoniazid sensitivity. In cases of nonspecic shadows
on chest X-rays, antibiotics should be given to look for the resolution of shadows.
Contrast-enhanced computerised tomographic scan (CECT) of the chest and exible bronchoscopy may be required for conrming the diagnosis. In diagnosed tuberculosis cases, imaging is often required to assess disease extent, evaluate therapeutic
response, or look for residual disease for treatment extension. Imaging is also crucial for guiding aspiration, biopsies and therapeutic drainage of uid collections.
Keywords Tuberculosis · Microbiological · Diagnosis · Clinical · Radiological ·
Intrathoracic · Lymph node CNS · Abdominal · Osteoarticular
A. Kumar · B. Dhingra (*)
Department of Pediatrics, AIIMS Bhopal, Bhopal, India
e-mail: bhavna.pediatrics@aiimsbhopal.edu.in
© The Author(s), under exclusive license to Springer Nature Singapore Pte
Ltd. 2023
A. Singh, D. Sharma (eds.), Diagnosis of Mycobacterium,
https://doi.org/10.1007/978-981-99-5624-1_2
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A. Kumar and B. Dhingra
2.1 Introduction
The lifetime risk of developing tuberculosis is about 5–10% in people infected with
Mycobacterium tuberculosis, primarily within 5 years of infection [1].
Microbiological diagnosis of tuberculosis is essential for tuberculosis control but is
often ignored and neglected. Acid-fast smear of an expectorated sputum specimen
was the rst investigation to conrm microbiologically discovered over a century
ago. We are still relying on it with a few modications. Unfortunately, around 50%
of cases are smear-negative, resulting in the under- diagnosis of a substantial percentage of the world’s tuberculosis cases. The late diagnosis of these cases in an
advanced stage of the disease leads to signicant transmission in the community by
that time. The risk of tuberculosis is increased in any patient with the following
demographic characteristics: residence in a high-TB prevalence state; contact with
an active pulmonary case of tuberculosis; residence in a setting with community
exposure, such as a nursing home, guest house, community shelter, prison in which
occult exposure to tuberculosis might have occurred; or underlying immunosuppression due to HIV infection, other illnesses, or the administration of immunosuppressive drugs, which reduce immunity, particularly biologicals [2–4]. Failure to
consider tuberculosis in the differential diagnosis of at-risk patients leads to delays
in the diagnosis and administration of antitubercular drugs [5, 6]. Continued education and community awareness about tuberculosis are essential in this situation.
2.2 Available Diagnostic Tests forTB [7, 8]
• Smear: it is commonly performed on sputum and gastric aspirates. Use singu-
larly and if only rapid nucleic acid amplication test (NAAT) is not available. It
is positive in only 10–15% of children.
• Culture: liquid culture takes 2–6weeks time in isolation, while invitro drug sen-
sitivity testing takes more time. The time involved in sensitivity testing decreases
when used with line probe assay (LPA).
• Nucleic acid amplication test (NAAT): NAAT-like cartridge-based (CBNAAT)
or line probe assay (LPA) signicantly increases the yield. As we have moved
towards an upfront universal drug sensitivity testing (U-DST) strategy by culture
and/or molecular methods for all TB cases (new as well as retreatment cases),
microbiological diagnosis must be attempted in all presumptive cases, especially
in drug-resistant (DR) TB suspects. Collect good-quality samples for testing—
smear, NAAT, LPA and culture. Always try to send for all investigations simulta-
neously. Where sputum is not available for examination, use alternative
specimens, like gastric aspirate (GA), induced sputum (IS), bronchoalveolar
lavage (BAL) and appropriate extrapulmonary TB (EPTB) specimens. Recent
advances in technology has made a complete shift in the paradigm of writing
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simple diagnosis like Mycobacterium tuberculosis (MTB) to MTB with its sen-
sitivity pattern. The approved rapid NAAT tests have made it possible to simul-
taneously detect the presence of MTB and resistance to rifampicin, even in
smear-negative samples directly. The rapid and direct detection of resistance to
isonicotinic acid hydrazide (INH) is also possible but less universally (for smear-
positive specimens). Hence, the current strategy focuses more on microbiologi-
cal diagnosis at all ages and for all types of system involvement.
• Chest radiography: nonspecic ndings and variable interpretation are its limita-
tions, but it is very useful in sputum-negative probable TB cases, especially in
children where TB is paucibacillary, and getting adequate good-quality speci-
mens is challenging.
• TB skin test and interferon-gamma release assays (IGRAs): IGRAs and skin
tests neither diagnose active TB disease nor predict the risk of developing active
TB disease in infected individuals. IGRAs are technically complex and costly
investigations. Blood samples must be processed within 8–30 h (preferably
within 6h) of collection while the white blood cells (WBC) remain viable. Errors
during the collection and transport of blood specimens or while performing and
interpreting the assay can decrease the accuracy of IGRAs. C-Tb is the next-
generation skin test for the detection of tuberculosis, which is an easy-to-use
point-of-care specic test (based on ESAT-6 and CFP-10 antigens of MTB and
unaffected by bacille Calmette-Guérin (BCG) vaccination status. It is an easy
replacement for the puried protein derivative (PPD) test (tuberculin skin test
(TST)), as administered via intradermal injection of 0.1mL using the Mantoux
technique. An induration of ≥5mm indicates an infection with Mycobacterium
tuberculosis. The safety prole is comparable to TST (local skin reactions).
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This chapter will review approaches to the clinical and radiological diagnosis of
pulmonary and extrapulmonary tuberculosis.
2.3 Clinical Suspicion ofTuberculosis
Detailed history and examination are essential for the symptom characterisation of
tuberculosis, followed by focused investigations. The proper characterisation of
constitutional symptoms increases the positive predictive value of these symptom
complexes in diagnosing tuberculosis [7, 8]:
• Fever for 2weeks or more: persistent (>2weeks) and unexplained fever (>38°C).
reported by a person/guardian or objectively recorded at least once.
• Persistent (>2weeks), non-remitting cough.
• A denite weight loss (≥5% loss in the past 3months) or failure to gain weight
in the past 3months despite adequate nutrition.
• Persistent peripheral lymphadenopathy (>2cm in size).
• Insidious onset meningitis.
• Gibbus of the spine.
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• Exposure to an infectious TB case (patient with lung or airway involvement): the
risk is highest among contacts of infectious sputum-positive cases. In symptom-
atic patients, the exposure may be from sputum-negative index cases with unrec-
ognised coexisting pulmonary involvement. Contact with a person with active
tuberculosis within the last 2 years (more signicant in the last 3months) may be
considered contact positive.
A. Kumar and B. Dhingra
2.4 Intrathoracic TB
In all suspected cases of intrathoracic TB based on constitutional symptoms, chest
X-ray and sputum examination should be done at the rst visit. However, in children
under 5years, getting the sputum specimen is challenging, so a chest X-ray should
be done rst, followed by gastric aspirate or induced sputum, depending on the
chest X-ray ndings (Fig. 2.1 Algorithm). In adults, both the X-ray and sputum
results should be interpreted simultaneously in the presence of constitutional symptoms of TB.
2.5 Chest Radiology
A chest X-ray is an essential tool for diagnosing pulmonary TB and osteoarticular
TB.Clinicians must know the TB-suggestive shadows on chest X-rays. Mistakes in
interpretation can lead to both under- and over-diagnosis. Poor-quality images, like
signicantly rotated, expiratory, and under- and over-exposed lms, should not be
reported for diagnosing tuberculosis. Remember the cofounders, like a thymic
shadow. Radiographic ndings in tuberculosis have been well described [6, 14–18].
2.5.1 Radiological Manifestations ofTB
• Highly suggestive imaging ndings for pulmonary TB.
– Hilar/mediastinal lymphadenopathy.
– Chronic bro cavitary disease.
– Miliary pattern.
• Non-specic radiology for pulmonary TB.
– Consolidations.
– Non-homogenous opacity.
– Ground glassing.
– Thin-walled cavities.
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Fig. 2.1 Algorithm for an approach to paediatric pulmonary tuberculosis [7, 8]. (Algorithm adapted from IAP NTEP Pediatric TB guidelines 2019 & 2021,
central TB division MOHFW New Delhi India)
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A. Kumar and B. Dhingra
• Lymphadenopathy on X-ray.
• Direct signs:
– Sharply demarcated and lobulated density obliterating the hilar point.
– Other structures making up the mediastinum and hilum can obscure it.
Indirect signs:
– The contour and calibre of the trachea.
– Compression of the tracheobronchial tree or splaying of the carina.
Remember in the current era of universal DST, all cases with radiological ndings must have tests for the microbiological conrmation of MTB and its resistance
to rifampicin (and INH). Antibiotics should always have been given in non-specic
shadows, and bacteriological tests are pursued only in cases with persistent pneumonia. In case the need is felt, a specialist opinion may be taken. Investigations like
CT chest and exible bronchoscopy may be needed to establish the diagnosis
(Figs.2.2 and 2.3).
Fig. 2.2 Chest X-ray of intrathoracic tuberculosis showing varied presentations: hydropneumothorax (a), miliary pattern both lung elds (b), inltrate right lung and left upper and lingular lobes
(c), pleural effusion (d), brosis right upper and left lung (e), cavitary lesion (f)
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Fig. 2.3 Chest X-ray showing cavitary consolidation of the right lung in a 12-year-old girl. NCCT
chest of the same patient showed cavitary consolidation in the right lung with broncho-cavitary and
cavitopleural stula
2.6 Lymph Node Tuberculosis (TBL)
Progressive enlargement of lymph nodes (cervical/axillary/inguinal regions), size
>2 cm, matted lymph node, chronic sinus with constitutional symptoms and/or history of TB contact is suggestive of TB lymphadenitis. Non-response to oral antibiotics is also indicative of investigation for TB lymphadenitis. TBL should not be
suspected with a small (<2cm) lymph node persisting >1year without systemic
symptoms and a history of scalp lesions/skin lesions. Waxing and waning lymphadenitis because of recurrent cough and cold are against the diagnosis of TB lymphadenitis. Essential investigations are ne-needle aspiration cytology (FNAC), acid-fast
bacilli (AFB) smear, cartridge- based nucleic acid amplication test (CBNAAT
(Xpert MTB/RIF) and chest X-ray to look for mediastinal lymph nodes with
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ultrasonography (USG) abdomen to look for abdominal LN.Optional investigations
are lymph node biopsy, if diagnosis is uncertain and CECT neck and chest if mediastinal widening in chest X-ray and diagnosis uncertain on aspiration [7, 8].
A. Kumar and B. Dhingra
2.7 CNS Tuberculosis
CNS tuberculosis includes tubercular meningitis and/or tuberculomas. Both are
associated with high morbidity and mortality if treatment is delayed [7, 8].
CNS tuberculosis should be suspected in a patient having a combination of fever
with one or more of the following: headache, vomiting, irritability/lethargy/drowsiness, malaise, anorexia, weight loss, stagnation/regression of developmental milestones in children, seizures, and weakness of the arms/legs. Symptoms usually have
more than 5–7day duration with insidious onset. Fever may be absent in those only
with tuberculomas. A history of contact with a case of infectious TB is essential to
suspect TBM.The history of treatment for primary complex or other forms of TB
must be checked.
The examination should include an assessment of the sensorium (Glasgow Coma
Scale) and signs of meningeal irritation (neck stiffness, Kernig’s sign and
Brudzinski’s sign). CNS examination including fundus examination of eye should
be done for papilledema, optic atropy and/or choroid tubercles. Peripheral lymphadenopathy and chest examination are also essential to look for TB elsewhere.
Essential investigations are complete blood count (CBC), blood sugar, cerebrospinal uid (CSF) cytology and biochemistry, Mycobacteria Growth Indicator Tube
(MGIT) culture, NAAT (CBNAAT/Xpert MTB-Rif/TruNAAT/UltraNAAT), aerobic culture, HIV, CT head with contrast (MRI brain preferred), CXR, and gastric
lavage/induced sputum in patients where CXR is abnormal. Desirable investigations
are USG abdomen and CECT chest/abdomen to look for extra-cranial sites of
infection.
2.8 Abdominal Tuberculosis
Abdominal tuberculosis may present in one or more of the following forms [7–9]:
• Intestinal tuberculosis: small bowel, large bowel.
• Nodal tuberculosis: mesenteric, retroperitoneal.
• Peritoneal tuberculosis: ascitic/wet type and dry type.
• Visceral tuberculosis: liver, spleen, pancreas, or as a part of disseminated
tuberculosis.
Abdominal tuberculosis may present in isolation or in association with other
forms of tuberculosis. Abdominal tuberculosis should be suspected in a patient having the presence of two or more of the following symptoms for >2weeks: fever,
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recurrent or chronic abdominal pain, abdominal distension, abdominal mass,
chronic diarrhoea, anorexia, unexplained weight loss, features of subacute intestinal
obstruction. Other less common symptoms are upper or lower GI bleeding, jaundice, gastric outlet obstruction, constipation, chronically discharging perianal stula, obstructive jaundice, dysphagia or odynophagia. The patient may or may not
have systemic features of fever, weight loss or anorexia. Isolated recurrent or chronic
pain without other symptoms is usually not due to TB.History should be asked for
the involvement of other sites, as well as similar illnesses in the past, H/O ATT
intake in the past, H/O contact for TB, and H/O ATT intake in the family (current or
in the last 2years), including HIV status.
• Intrathoracic: cough with or without sputum, shortness of breath, noisy breathing.
• Central nervous system (CNS): altered behaviour, altered sensorium, seizures,
vomiting, headache, neck pain.
• Tuberculous lymphadenitis (LN TB): cervical swelling or swelling anywhere
else in the body.
• Osteoarticular TB: back pain, stiffness in the back, chronic joint swelling.
• Non-healing or chronically discharging sinus.
Examination ndings
• Anthropometry: malnutrition.
• General examination: pallor, icterus, lymphadenopathy, pedal oedema.
• Per abdomen: abdominal distension, ascites, doughy feel of the abdomen.
• Hepatomegaly/splenomegaly/hepatosplenomegaly.
• Palpable lump (matted mesenteric lymph nodes).
• Abdominal distension with a hyper-resonant note on percussion with increased
or diminished bowel sounds (gaseous due to obstruction).
• Examination of other systems according to symptoms.
• Red ags for the diagnosis of abdominal TB with chronic abdominal pain.
The following USG ndings are suggestive of abdominal TB:
• Abdominal LN with central necrosis, conglomerate lymph nodes, peripheral
enhancement.
• Loculated ascites, mesenteric thickening, Caked omentum, multiple SOLs in the
liver or spleen.
• Abdominal lymphadenopathy (SAD >15mm) with other abnormal ndings.
Diagnostic workup of abdominal TB is a multimodality evaluation, including a
combination of clinical examination, laboratory, radiology, endoscopy, microbiology and histopathology. Do not investigate for TB or start anti-tuberculosis therapy
(ATT) in case of recurrent/chronic abdominal pain without red ag signs and recurrent/chronic abdominal pain with sub-centimetric mesenteric lymphadenopathy.
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