Dr Dhammika Vidanagama, Consultant Microbiologist, National TB Reference Laboaratory, Welisara

1. Detection of HIV-TB co infection
New approaches
Dr. Dhammika Vidanagama
Consultant Microbiologist
National TB Reference Laboaratory
Welisara
Pre congress SL- CoSHH 05.10.2017

2. HIV-Associated Tuberculosis
• Significance of early detection
• Delayed detection –Why?
• New approaches to confirm active TB
• LTBI

3. TB in PLHIV …. double trouble ??
• is harder to diagnose
• spreads faster
• is more likely to be fatal if left untreated
• can spread to other parts of the body
• is more likely to recur after being treated
• is harder to treat if it’s a drug-resistant TB strain.

4. Impact - mortality
• One third of deaths among PLHIV were due to TB
• TB is the leading cause of death among PLHIV
• Including among those taking antiretroviral therapy (ART)
• In 2015
• Deaths from HIV and TB co-infection: 400,000
• Deaths from TB alone: 1,400,000
• Deaths from HIV alone: 800,000

5. Impact - morbidity
• TB is the most common presenting illness among PLHIV
• PLHIV 17-22 times more likely to develop TB than persons without
HIV
• TB incidence
• doubles in the first year following HIV infection
• can occur at any CD4 cell count
• risk increases with progressive immunodeficiency.
• Globally 11% of the incident TB cases in 2015 are estimated to have been among
people living with HIV.

6. Pathogenesis - synergy
Progression from latent to active TB
• lifetime risk of 5-10% for HIV negative people
• this same figure is the annual risk for PLHIV
• HIV/TB dubbed a “deadly syndemic ”

7. TB in PLHIV
• Active disease - PTB/EPTB/disseminated disease
• Latent infection
• Lifetime risk of reactivation/ re-infection
• As immunosuppression advances,
• the radiographic presentation becomes less typical
• extrapulmonary and disseminated disease become more common

8. Recommended action
• WHO recommends 12 TB/HIV collaborative activities, including the
Three I's for TB/HIV.
• The Three I's for TB/HIV
• Intensified case finding = ICF
• Isoniazid preventive therapy = IPT
• Infection control for TB = IC

9. Delayed diagnosis
• Even in the era of widespread availability of ART, many PLHIV who
have had access to HIV care die with TB undiagnosed.
• WHO recommends that
• All PLHIV should be screened with a clinical algorithm at each clinical
encounter
• Those who do not report any one of: current cough, fever, weight loss or night
sweats are unlikely to have active TB and should be offered IPT

12. Symptoms of TB in PLHIV
• PLHIV with pulmonary TB may have the classic symptoms of TB
• but many people with both TB and HIV infection have few symptoms
of TB or even less specific ones.
• In addition, up to a fifth of people with both pulmonary TB and HIV
have normal chest X-rays.
• HIV positive people with TB may indeed frequently have so called
“sub clinical” TB, which often is not recognized as TB and
subsequently there are delays in both TB diagnosis and TB treatment
• PLHIV are also more likely to have EPTB
• 40-80% PLHIV with TB have EPTB, compared with 10-20% of people without
HIV.

13. Early detection
• One meta-analysis demonstrated that absence of fever, night sweats,
weight loss, and cough of any duration had a 97.7% negative
predictive value to exclude active TB infection.
• However, asymptomatic subclinical TB infection has been described,
particularly in locations with a high prevalence of TB ; this would be
missed with a symptom screen alone

14. Chest X-Ray
• As chest radiographs may appear normal in up to 21% of those with
culture-positive TB and CD4 counts of <50 cells/µL, a high index of
suspicion must be maintained in evaluating an HIV-infected patient
with symptoms suggestive of TB.

15. Conventional tests
• PLHIV have higher rates of sputum smear-negative disease.
• Smear-negative, culture-positive TB is more common and occurs
more frequently with advanced immunosuppression.
• Rates of AFB smear-negative disease vary widely but have been
reported as high as 66%

16. TB Diagnostic pipeline………………

17. TB cultures
• Given the high rates of AFB smear-negative disease, culture can be
essential to confirm the diagnosis of TB.
• Use of 1 MGIT culture identified 71% of TB cases, and use of 3 MGIT cultures
had the highest yield of strategies evaluated, identifying 98% of TB cases.
• Incremental yield - a second MGIT culture identified 17% more TB cases,
whereas the third MGIT culture had yielded 10% more cases than the second
culture.
• When expectorated sputum specimens are AFB smear negative,
further evaluation may be indicated.
• Bronchoscopy with BAL and transbronchial biopsy may be useful in
the evaluation of persons with abnormal CXR when sputum smears
are negative.

18. What is available in Sri Lanka?
• Bactec 960 MGIT automated system for liquid culture & DST
MPT64 antigen
rapid MTBC identification
e.g.

19. DIAGNOSING TB AMONG PLHIV
• Sputum smear microscopy has a particularly low sensitivity for detecting
TB among PLHIV.
• People in later stages of HIV infection and with compromised immune systems often
release fewer organisms into their sputum, at concentrations below the threshold for
visual detection under a microscope.
• For PLHIV with a negative smear microscopy result but who are still
presumed to have TB, bacterial culture has been the only diagnostic
option.
• However, culture can only be undertaken at central level laboratories, and results are
generally available after a number of weeks or months.
• TB culture is therefore not good enough for PLHIV, who need a speedy TB
diagnosis and prompt treatment.

20. Nucleic Acid Amplfication based tests -WRD
Cartridge based NAAT – Automated Real-time PCR platform
• Xpert MTB/RIF should thus be made widely available as the initial
diagnostic test in HIV clinics and HIV prevalent* settings
• It is a rapid, simple and highly sensitive TB diagnostic tool that can
easily be deployed close to the point of patient care.
*HIV-prevalent settings: where the adult HIV prevalence rate among pregnant
women is ≥1% or HIV prevalence among tuberculosis patients is ≥5%.

21. What is available in Sri Lanka?
• GeneXpert® (XpertMTB/RIF) - detects MTB and rifampicin resistance
• Used at NTRL from 2013 – A XVI module in use now
• Service expansion with GeneXpert IV module systems in all 9
provinces in 2017

22. What is available in Sri Lanka?
• Line Probe Assay (LPA – Hain GenoType®)
• MTBDRplus
• MTBDRsl

23. SUMMARY OF WHO RECOMMENDATIONS ON
XPERT MTB/RIF FOR PLHIV
1. Xpert MTB/RIF should be used rather than conventional microscopy,
culture and DST as the initial diagnostic test in adults and children
suspected of having HIV-associated TB or of having MDR-TB (strong
recommendation).
2. Xpert MTB/RIF should be used in preference to conventional microscopy
and culture as the initial diagnostic test for CSF specimens from patients
suspected of having TB meningitis (strong recommendation).
3. Xpert MTB/RIF may be used as a replacement test for usual practice
(including conventional microscopy, culture or histopathology) for testing
specific non-respiratory specimens (lymph nodes and other tissues) from
patients suspected of having extrapulmonary TB (conditional
recommendation).

24. THE ROLE OF XPERT MTB/RIF IN THE
CASCADE OF CARE FOR PLHIV
• PLHIV should be screened for TB symptoms at each visit to a health
facility or each encounter with a health care worker.
• Adults and adolescents living with HIV look for any one of the
following symptoms: current cough, fever, weight loss or night sweats
• Children living with HIV look for any one of the following : poor
weight gain, fever, current cough or contact history with a TB case
• If the evaluation shows any of the above, PLHIV should be tested for
active TB, preferably by Xpert MTB/RIF

25. EVIDENCE ON USE OF XPERT MTB/RIF FOR
DETECTING TB IN PEOPLE LIVING WITH HIV
• Xpert MTB/RIF is sensitive and specific for the detection of PTB when
used as the initial diagnostic test in adults presumed to have HIV-
associated TB.
• It detects 79% of the pulmonary TB cases among PLHIV, which is far
superior to smear microscopy.
• Increases case detection of TB by around 45% compared with microscopy
among PLHIV enrolling in ART in South Africa.
• Improves the quality of rapid TB diagnosis among PLHIV by providing
bacteriologically confirmed diagnosis in 36 – 75% of pulmonary TB patients
who are smear-negative.
• Facilitates earlier diagnosis and reduces time-to initiation of TB
treatment, especially for smear negative pulmonary TB and at
decentralized clinics in areas of high HIV prevalence

26. Xpert MTB/RIF
• Xpert MTB/RIF improves sensitivity, timeliness of detection of
rifampicin resistance in adults and children living with HIV.
• Use of Xpert MTB/RIF to detect TB among PLHIV thus facilitates timely drug
susceptibility testing (DST) for detection of MDRTB or XDR-TB and treatment
initiation with the correct drug regimen
• However, like any diagnostic tool, Xpert-MTB/RIF may be unable to
impact TB morbidity and mortality, unless the test is embedded into
a supportive and efficient health care system

27. HIV-positive or unknown
• If suspected of having TB based on symptoms and no danger signs -
Perform Xpert MTB/RIF
• If Xpert MTB/RIF-negative for TB or test not available - Perform further
investigations for TB
• Include chest X-ray, clinical assessment and a repeat Xpert MTB/RIF using a fresh
specimen.
• Refer a sample for TB culture where feasible.
• If Xpert MTB/RIF is not available, conduct acid-fast bacillus (AFB) microscopy. AFB-
positive is defined as at least one positive smear, and AFB-negative as two or more
negative smears.
• If extrapulmonary TB is suspected, extrapulmonary specimens should be
obtained and sent for culture and abdominal ultrasound may be performed.
• A urine lateral flow lipoarabinomannan (LF-LAM) assay should not be
performed for people with no danger sign.

28. HIV positive/unknown -
Suspected of having TB with danger signs
• Danger signs
• respiratory rate >30 per minute
• temperature >39°C
• heart rate >120 beats per minute
• unable to walk unaided
• If any one of above + Perform Xpert MTB/RIF
• If Xpert MTB/RIF-negative or no test available
• Clinical worsening or no improvement after 3–5 days
• Start presumptive TB treatment • ART • Co-trimoxazole preventive therapy
• Further investigations for TB and other diseases • Complete the course of parenteral
antibiotics

29. Biomarker tests - LAM
• Lipoarabinomannan in urine
• Lateral Flow - LAM (Alere - Determine) has limited WHO
recommendation for the following types of patients
• Adult PLHIV with signs & symptoms of PTB/EPTB
• Inpatients with CD4 =/< 100
• Or seriously ill regardless of CD4 count
• Or adult outpatient with above conditions
• And HIV positive children (low sensitivity)
• NOT recommended for diagnosis/screening of TB in other patients

31. LAM in Urine
• A true point-of-care test
• Lateral-flow dipstick that can be dipped in patient urine, and it requires
minimal technical expertise to process.
• LAM testing appears to perform better in PLHIV than in those without HIV,
particularly in those with CD4 counts of <50 cells/µL, which in part may be
attributable to the higher rates of disseminated TB in that population.
• The overall sensitivity in culture-positive TB patients with HIV infection is
low (40-60%) but increases to 67-85% in those with CD4 counts of <50
cells/µL.
• Specificity has been reported as 99-100% in HIV infection.
• Given its limited sensitivity, urine LAM has been proposed as a "rule in" test
but appears inadequate as a stand-alone "rule out" test for TB.

32. LAM test
• Imperfect sensitivity - a negative test must still be followed up with
other testing to rule out TB
• (56% pooled sensitivity based on five studies of people with CD4 <100/mm3)
• Recommended due to
oextremely high mortality of people with TB and HIV (TB is thought to be the
cause of death in nearly 40% of HIV-positive patients, half of which is
undiagnosed) and
o challenges in diagnosing TB in people with low CD4 counts
o an inexpensive ($2.26 per test), simple, rapid and noninvasive test

33. LAM test
• The first TB test to ever demonstrate a mortality benefit in a
randomized controlled clinical trial:
• among 578 people with HIV in hospitals in South Africa, Tanzania, Zambia, and
Zimbabwe, using LAM was associated with an absolute reduction of all-cause
mortality at eight weeks of 4% (95% confidence interval [CI]: 1%–7%) from 25%
to 21%, and a relative risk reduction of 17% (95% CI: 4%–28%).
• This difference appeared to be attributable to the test’s allowing earlier
initiation (by one day on average) of anti-TB therapy.

34. Latent TB in PLHIV
Among PLHIV
• Risk of progression from LTBI to TB disease is reduced by
• antiretroviral treatment and
• treatment of LTBI
• Treatment of LTBI (as defined by a positive TST) decreases the risk of
• TB disease by 62%
• death by 26%
US CDC - All persons should be tested for LTBI at the time of HIV
diagnosis, regardless of their epidemiological risk of TB exposure
WHO – testing not essential before IPT

35. Detection of LTBI
• Persons with negative diagnostic tests for LTBI, advanced HIV
infection (CD4 cell count <200 cells/µL), and without indications for
initiating empiric LTBI treatment (i.e., no recent exposure to a culture-
confirmed TB case) should be re-tested for LTBI once they start ART
and attain a CD4 count ≥200 cells/µL to ensure the initial test was a
true negative result
• Annual testing for LTBI using TST is recommended for HIV-infected
persons who are at high risk for repeated or ongoing exposure to
persons with active TB
• US – CDC –( Low TB Prevalence )

36. Tuberculin Skin Testing
TST has several disadvantages:
• the requirement for two visits to place and read the test
• decreased specificity (false positive results) among persons who
received BCG vaccination
• decreased sensitivity (false negative results) among persons with
advanced immunodeficiency

37. Interferon Gamma Release Assays
Compared to the TST, IGRAs have
• higher specificity (92%–97% vs. 56%–95%)
• better correlation with surrogate measures of exposure to M.
tuberculosis
• less cross-reactivity with BCG vaccination and non-tuberculous
mycobacteria.
• Progressive immunodeficiency is associated with decreased sensitivity
of IGRAs, though the effect of immunodeficiency on the sensitivity of
IGRAs may be less than its effect on the sensitivity of the TST

38. Excluding active TB before IPT
• Symptom based screening
• Absence of symptoms has good negative predictive value for culture-positive
TB, though this varies depending on pre-test probability.
• Addition of a Chest X-ray improved sensitivity of this screening
algorithm, but decreased specificity.
• Sputum culture is the gold standard for diagnosing pulmonary TB
disease, but this is not cost-effective in screening asymptomatic HIV-
infected persons
• Therefore, symptom screening (asking for cough of any duration)
coupled with chest radiography is recommended to exclude TB
disease in a patient with a positive screening test.

39. TB diagnostic facilities in Sri Lanka
Laboratory Tests available Location
National TB reference
Laboratory
Microscopy (ZN & FM)
Cultures (LJ & Liquid) , DST
Xpert(MTB/RIF)
LPA (FLD & SLD)
NHRD premises, Welisara
Intermedieate TB
Laboratories
LJ culture
Xpert(MTB/RIF)
DCC Kandy, PGH Rathnapura
DCC Jaffna*
TH Karapitiya - Galle*
GeneXpert services Xpert(MTB/RIF) Above labs + NHSL,
TH – Badulla,Kurunegala,
Anuradhapura, Batticaloa
District Chest Clinic
Laboratories
Microscopy
Mantoux testing, CXR
26 DCCs
Microscopy centers Microscopy >150 Hospitals

40. Sri Lankan guidelines related to HIV/TB
NPTCCD publications/ MoH circulars
• National Manual for Tuberculosis Control
• National Guidelines for Programmatic Management of Drug Resistant
Tuberculosis
• National Guidelines for use of Xpert(MTB/RIF) for diagnosis of TB
• Guidelines on Isoniazid Prophylactic Therapy