Tuberculosis (TB)

Tuberculosis (TB)
Infection is caused by the bacterium Mycobacterium tuberculosis. Respiratory TB is the
commonest presentation, but TB can infect other body sites. Only respiratory TB is infectious.
TB is a notifiable disease.
SPREAD BY Droplet spread: patients with respiratory TB may expel droplets containing
infectious TB bacteria into the air when they cough or sneeze. If these droplets are inhaled
they can cause TB infection. Prolonged or close exposure is generally required to catch TB.
I N F E C T I O U S P E R I OD The incubation period is variable: approximately 4–12 weeks from
exposure to primary infection, though the disease may reactivate months or years later.
A patient with infectious respiratory TB will remain infectious indefinitely if untreated.
Patients are usually no longer infectious once they have completed 2 weeks of appropriate
therapy.
I N F E C T I O N C O N T R O L P R E C A U T I O N S Patients with known or suspected TB should
not be admitted to hospital unless necessary. Patients with respiratory TB should always be
isolated in a side room pending laboratory results, and should always be separated from
immunocompromised patients (HIV, transplant, oncology, etc.), either by admission to a
single room on a separate ward or in a negative-pressure room on the same ward. NICE
guidance states that mask, gown and isolation precautions are not required unless the
patient has multidrug-resistant TB (MDR-TB) or is undergoing an aerosol-generating procedure.
This is a change from previous practice and some hospitals still recommend apron,
gloves and FFP3 masks. Check your local policy.
1 Isolation Smear-positive patients – required until 2 weeks treatment
completed
Smear-negative or non-respiratory disease – not required
Children – required*
Drug-resistant TB – requires negative pressure isolation room
2 Hand washing Required
3 Gloves Not required unless handling body fluids
4 Apron Not required unless handling body fluids
5 Mask FFP3 mask required for MDR TB or aerosol-generating
procedures
6 Eye protection Not required
*Children with TB should be isolated until the source case has been identified, regardless of
AFB smear results. This is because the source case is likely to be a relative who visits the ward.
These visitors should only visit the isolation room and then leave – they should not spend time
in communal areas until they have been screened and infection excluded.
Patients should perform respiratory hygiene (Chapter 2). Aerosol-generating procedures
such as bronchoscopy should be carried out in a negative pressure room or bronchoscopy
suite. Staff should wear gowns, gloves and FFP3 masks.
S TA F F The number of staff caring for infectious TB patients should be kept to a reasonable
minimum, without compromising patient care. Staff who are likely to work with TB
patients should be fit tested for FFP3 mask use. Staff who work with patient or clinical
materials should complete a health check including TB assessment when they start in the
job. This includes a history/health questionnaire and BCG scar check. Mantoux skin testing
or interferon-gamma testing may be offered if appropriate.

VI S I T O R S Visitors should be restricted to immediate family and those who have already
been in close contact with the patient before diagnosis. Visitors are discouraged from
bringing in babies and children.
PAT I E N T T R A N S F E R Patient transfer should be kept to a minimum until the patient has
completed 2 weeks of treatment. Inpatients with smear-positive respiratory TB should wear
a surgical mask whenever they leave their room until they have had 2 weeks of treatment.
The receiving ward/department must be informed of the diagnosis. Patients should not
wait in communal areas such as waiting rooms.
L I N E N A ND LAUNDRY Linen and laundry should go into a red linen bag.
MORE INFORMAT I O N Tuberculosis infection rates are increasing, both in the UK and
worldwide. There are approximately 9000 cases in the UK each year, most of which occur
in cities (particularly in London).
Respiratory tuberculosis is active TB affecting any of the following: lungs, pleural cavity,
medastinal lymph nodes, larynx. Symptoms may include a cough lasting longer than
3 weeks, fatigue, weight loss, night sweats, dyspnoea, haemoptysis or chest pain. Some
patients are asymptomatic. Chest X ray is abnormal.
Non-respiratory tuberculosis may affect various body sites to cause bone and joint infection,
meningitis, lymphadenitis, pericarditis, disseminated (miliary) TB, genitourinary TB or
gastrointestinal TB.
HIV patients are at increased risk of symptomatic TB infection.
DI A G N O S I S O F T B Diagnosis of TB is usually by chest X-ray and three sputum samples
sent on consecutive days for acid-fast bacilli (AFB) investigation. Other samples such as
bronchial washings or gastric washings in children (who swallow sputum instead of coughing
it up) are acceptable. For non-respiratory TB, pus or tissue may be sent in a universal
container (not formalin).
A ‘smear’ of the sputum is examined under a microscope for AFBs. Results are used to
establish whether the patient is likely to be infectious to others: smear-positive patients are
infectious; smear-negative patients where the culture result is not yet known are potentially
infectious but low risk for transmission; and patients who are sputum smear and culturenegative,
or who have non-respiratory TB, are non-infectious. Patients whose bronchial
washings are smear-positive are not regarded as infectious unless their sputum is also
smear-positive or becomes so after bronchoscopy.
PCR and/or culture are required for full identification and sensitivity testing of AFBs.
Other tests for TB include interferon-gamma testing (a blood test for latent TB) and
Mantoux testing (a skin test used to diagnose latent TB).
MANAGEMENT The respiratory medical team and a specialist TB nurse should always be
involved in the management of TB. They oversee diagnosis, treatment and contact tracing.
Treatment requires at least 6 months of combination antibiotics with close follow-up.
Contact tracing in the hospital setting is only required if there was a delay in isolating the
patient. Other patients are considered at risk of infection if they have spent more than
8 hours in the same bay as an inpatient with sputum smear-positive TB who had a cough.
DR U G R E S I S TANCE Drug-resistant strains are more difficult to treat and have worse
outcomes. Patients with suspected MDR TB must be managed in a negative pressure room
and preferably transferred to a specialist unit. Staff and visitors should wear FFP3 masks.
Mono-resistant = resistant to one drug; poly-resistant = resistant to >1 drug (but not
MDR); multidrug resistant (MDR) = resistant to at least rifampicin and isoniazid; extensively
drug resistant (XDR) = resistant to rifampicin, isoniazid, a quinolone and an injectable agent