Infectious Risks of Open Tuberculosis in Patients

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Hello, doctor: The family member is a patient with open pulmonary tuberculosis and is currently undergoing treatment.
1.
Is the patient's sputum or oral secretions still infectious? 2.
If so, how long can the tuberculosis bacteria survive in the air after being expelled from the mouth? Thank you.

Xiao Cao, 0~9 year old female. Ask Date: 2001/10/13

Dr. Jiang Zhenyuan reply Pulmonology

1.
Patients with open pulmonary tuberculosis indicate that Mycobacterium tuberculosis is still present in their sputum.
Typically, the coughing of tuberculosis patients can release droplets containing the bacteria, and patients with tuberculous laryngitis can also spread the bacteria through speaking or singing, making them infectious.
When inhaled, the bacteria can infect the host's lungs, leading to pulmonary tuberculosis.
2.
Mycobacterium tuberculosis thrives in oxygen-rich environments, with an optimal temperature of 37 degrees Celsius.
It is resistant to acids and bases, sensitive to heat but not to cold; it can survive for six months in a refrigerator.
In dry and dark places, it can live for five months, so it is essential for patients' living or working environments to have good ventilation.
The bacteria are heat-sensitive and die quickly under sunlight; boiling for five minutes or heating to 65 degrees Celsius for 15 minutes will kill them, and they die instantly when exposed to fire.

Reply Date: 2001/10/13

More Info

Understanding the infectious risks associated with open tuberculosis (TB) is crucial, especially when a family member is diagnosed with this condition. Open TB, also known as pulmonary tuberculosis, is characterized by the presence of Mycobacterium tuberculosis in the sputum, which makes it contagious.
1. Infectiousness of Sputum and Oral Secretions: When a patient is diagnosed with open TB, their sputum and oral secretions can indeed contain viable TB bacteria, making them infectious. The risk of transmission is particularly high when the patient coughs, sneezes, or talks, as these actions can aerosolize the bacteria into the air. The infectiousness of the patient decreases significantly once they begin appropriate anti-tuberculosis treatment. Generally, after about two weeks of effective treatment, the majority of patients will no longer be contagious, as the bacterial load in their sputum decreases significantly. However, this can vary based on individual factors, including the patient's overall health and the presence of drug-resistant strains of TB.

2. Survival of TB Bacteria in the Air: The survival of Mycobacterium tuberculosis in the air is a critical concern. Once aerosolized, TB bacteria can remain suspended in the air for several hours, depending on environmental conditions such as humidity and temperature. However, they do not survive indefinitely. In general, the bacteria can remain viable in the air for a few hours, but the risk of transmission decreases significantly as time passes and as air circulation occurs. It is important to note that TB is primarily spread through prolonged exposure to an infectious individual in enclosed spaces, rather than brief encounters.

Given your situation, it is essential to take precautions to minimize the risk of transmission, especially to individuals with weakened immune systems, such as elderly family members. Here are some recommendations:
- Isolation: The patient should ideally stay in a separate room with good ventilation. If possible, they should use a separate bathroom. Visitors should be limited, and anyone entering the room should wear a mask.

- Hygiene Practices: Encourage the patient to practice good respiratory hygiene, such as covering their mouth and nose with a tissue or their elbow when coughing or sneezing. Dispose of tissues properly and ensure that the patient washes their hands frequently.

- Regular Monitoring: Family members who have been in close contact with the patient should undergo screening for TB. This may include a tuberculin skin test (TST) or an interferon-gamma release assay (IGRA) to determine if they have been infected.

- Follow-Up Care: Ensure that the patient adheres to their treatment regimen and attends all follow-up appointments. Regular monitoring of their sputum can help determine when they are no longer infectious.

In conclusion, while the risk of transmission from an open TB patient is significant, appropriate measures can greatly reduce this risk. It is crucial to maintain open communication with healthcare providers and follow their recommendations to ensure the safety of all family members. If you have any further concerns or symptoms, do not hesitate to seek medical advice.

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