Pulmonary Tuberculosis and Pregnancy

Tuberculosis (TB) is caused by Mycobacterium tuberculosis, M bovis, or M. africanum

These are slow-growing, aerobic, acid-fast bacilli, facultative intracellular organisms

The most common presentation is pulmonary tuberculosis which is a lower respiratory tract infection

TB is the leading infectious cause of mortality globally

Active TB during pregnancy is associated with increased risk of poor maternal and fetal outcomes

It is estimated that 1/3rd of the world’s population is infected with TB

Only 5-10% will progress to active TB in their lifetime (difficult to predict)

It is 20 – 50 times commoner in developing countries

TB is on the increase due to

• HIV
• Poor socioeconomic conditions
• Inadequate nutrition
• Overcrowding
• Antibiotics abuse
• Breakdown of health care systems
• Poorly supervised treatment
• Use of immunosuppressive drugs: e.g. steroids, cytotoxics
• Migration from regions of high endemicity

Worldwide, about 3 million women become afflicted with TB per annum and 750,000 die

TB is one of the leading infectious disease causes of death in women

The global burden of TB in pregnancy is not well known

Transmission is airborne from a contagious person

Pulmonary TB is the most common manifestation in pregnancy

Primary infection:

First infection with one of Mycobacterium tuberculosis complex – most commonly M. tuberculosis. It is usually subpleural, often in the mid to upper lung zones (primary/Ghon focus)

Within an hour of reaching the alveoli, tubercle bacilli reaches the draining lymph nodes at the hilum of the lungs and a few escape into the blood stream.

Host response:

Initially infiltration with neutrophil granulocytes

Rapidly replaced by alveolar macrophages which ingest the tubercle bacilli

Interact with the T lymphocytes with development of cellular immunity (can be demonstrated 3-8 weeks by a positive tuberculin skin test)

The bacilli evade death and multiply within these macrophages

Delayed hypersensitivity type reaction occurs resulting in tissue necrosis (caseous necrosis) with at least 20% of these containing tubercle bacilli, initially lying dormant but capable of reactivation

Possible fate of Primary infection

Latent TB: asymptomatic, non-infectious state after the host has mounted an effective granulomatous response.

Primary TB: refers to active disease within the first two years of infection, symptomatic and infectious

Reactivation disease: active disease after a period of latency beyond two years.

Current opinion holds that pregnancy and TB do not affect each other’s course.

However, active TB has adverse obstetrical and neonatal outcomes:

• Miscarriage
• Preterm labor
• Low birth weight
• Antenatal admission
• Anemia in pregnancy
• Preterm rupture of membranes
• IUGR
• Congenital tuberculosis (Rare)
• Prematurity

Pregnancy does not appear to increase susceptibility to TB infection or progression from latent to active TB

Pregnancy delays diagnosis of TB due to masking of symptoms and hesitancy in screening for TB as a differential

Diagnosis requires a high index of suspicion

Multidisciplinary: Obstetrician, pulmonologists, infectious unit, dietician, hematologists, microbiologists etc.

• History
• Examination
• Investigations
• Treatment

Breastfeeding may continue in women being treated for LTBI

Mycobacterium tuberculosis does not enter breast milk

Anti-Koch’s cross breast milk but have not been found to produce toxicity in the newborn

Mothers with active TB who may transmit the disease:

• Should not be in direct contact with the baby
• Can express breast milk to feed the baby except there is a tuberculous breast lesion/ulcer involving both breasts
• Infants should have chemoprophylaxis with INH and RIF for at least 3 months
• However, if mother is undergoing treatment and non-infectious, chemoprophylaxis is not required

Mothers with Tuberculous Breast Lesion

Should not breastfeed from the affected breast until lesion heals

Should express and discard breast milk from affected breast to maintain breast milk supply

May resume direct breastfeeding from the affected breast when she is no longer considered infectious i.e. amelioration of signs and symptoms, has been on therapy for at least 2 weeks and repeat smear is negative

Refers to TB in other parts of the body

It is usually not infectious

Most common sites are lymph nodes, bones, CNS (meninges, intracranial tuberculomas), urogenital tract

TB can be transmitted from mother with active TB disease to the fetus transplacentally through the bloodstream, lymphatics or amniotic fluid. Therefore, all infants should be evaluated for congenital TB

Congenital TB may present in the early neonatal period with sepsis, bronchopneumonia, hepatosplenomegaly, poor feeding

Although rare, it has a high mortality rate.

Evaluation in suspected congenital TB include histologic and mycobacterial culture of the placenta in addition to neonatal evaluation

Multidrug resistant TB is TB resistant to the two first line or most effective TB medications – Rifampicin and Isoniazid

It necessitates treatment using second line drugs for which there is limited clinical experience

These second line drugs may be successfully used without significant harm to the mother and child and without requiring therapeutic abortion

Any TB positive patient should be tested for concurrent HIV infection because HIV greatly increases risk of progression to active TB

Pregnant women with HIV should be screened early in pregnancy for TB and evaluated

Drug interactions between HIV and TB medications especially rifampicin complicates TB treatment during pregnancy

Second line drugs:

• Fluoroquinolones
• Amikacin
• Cycloserine
• Clofazimine
• Meropenem/Imipenem
• etc.

TB remains an increasingly common infectious disease among pregnant women worldwide

Diagnosis of TB in pregnancy is frequently delayed and a high index of suspicion is required to detect it

Its management is multidisciplinary

High index of suspicion is required in its diagnosis

BCG is a live attenuated vaccine and contraindicated in pregnancy