Tuberculosis Flashcards
What is the function of the encasing waxy coat of TB?
Protects bacteria from antibiotics
Current TB treatment
Isoniazid
Pyrazinamide
Ethambutol
Rifampicin
How many people have died of TB so far?
100,000,000
Old treatment for TB prior to abx
People sent to sanitoriums
Sunshine, rest and good food
Lessons outside
Light therapy on spinal TB
What year was TB declared a global health emergency?
1993
How many people are infected with TB worldwide?
2 billion
How many new cases of TB are there a year?
9 million
How many people die of TB a year?
1.7 million
What is the cut off for a county to be consider high risk for TB
Incidence of 40/100 000
How is TB transmitted?
Airborne organism - smear +ve TB
Regular contact = 8 hours cumulative contact over 3 months
Immunosuppressed or co-morbidities
What are the key factors affecting transmission of TB?
Infectiousness of person = 4 + AAFB and productive cough
Environment of exposure = park/small enclose space
Duration of exposure = 8 hours
Virulence of organism
Susceptibility of the contact
Related factors of TB
Poor housing Over crowding Poor nutritional status Lowered immunity Alcohol/HIV +ve/ drug abusers Age young and old Ethnic background
What does the process of ‘primary complex’ involve?
Droplets inhaled, lodge in alveoli > ghon focus develops > bacteria transported to lymph nodes > 6/10 weeks = calcification/scarring of granulomas (prevents further spread of infection)
What is miliary TB ?
Primary infection not controlled
Bacteria spread beyond primary complex via lymphatic system and blood stream
Lodge in any or many organs
What are the two eventualities of miliary spread?
Resolves spontaneously
Develop into localised infections in about 10% people - meningitis, osteomyelitis.
How many people infected, actually develop primary TB disease?
5%
How many people infected develop post primary disease or reactivation ?
10-15%
Pathogenesis of post primary disease/TB reactivation
Disease emerges if immunity wanes or later in life;
Viable bacilli multiply and cause immune system to become overwhelmed. (Non-Effective t-cell function) >
Lymphocytes produce cytotoxic substances causing caseation >
Cavity formation
Define infectious TB
Pulmonary TB , smear positive
Define non-infectious TB
Any site (including pulmonary) diagnosed by culture result (smear negative)
What is environmental TB?
Non tuberculosis mycobacterium
Not public health risk as confined to the patient and can’t be transmitted.
Who is affected by environmental TB?
Patients with pre-existing lung disease e.g. Cystic fibrosis
How do you treat environmental TB?
Longer treatment period
1 yr 18 months as bacteria already resistant to some drugs
What is empirical TB?
Patient with all clinical signs of TB but it’d never cultured. Improve on TB treatment
Why and to who would would TB chemoprophylaxis be given to?
People infected with TB but no signs of disease i.e. Latent TB
Young children > 35 years
HCWs any age showing signs of latent TB
Signs and symptoms of TB
Persistent cough 3/52 or 2-3/12 Poor appetite Weight loss (cytokine mediated) Chest pain (if pulmonary) Enlarged glands (particularly children and young Asians) Night sweats (cytokine mediated)
Investigations performed by GP
Sputum x 3 early morning ruined for c&s and AAFB
chest x-Ray
Refer to TB Team or chest clinic
Hospital investigations for TB
Tuberculin skin testing Bronchial washings Biopsy Early morning urine Interferon gamma release test (IGRA) CT scan
What is tuberculin skin or Mantoux testing
Checks for TB immunity
Doesn’t differentiate between BCG and TB disease immunity
When are bronchial washings used?
If patient not producing sputum
What are the requirements for urine testing for TB?
1st urination x 3
Culture and sensitivity
What does the IGRA test do?
Determines immunity by measuring the gamma interferon response to specific antigens
Differentiates between TB and BCG immunity as measures the amount of IFN gamma produced by cells met with mtb antigen.
What are the treatment aims for TB?
Reduce transmission
Cure (minimum interference/shortest time/quality of life)
Prevent death - rare in the uk due to late presentation, dx missed
Avoid relapse
Prevent emergence of drug resistance
What is the cure rate for TB
97-98%
What is secondary drug resistance
If abx taken intermittently and not for the right amount of time - drug resistance can occur
What is primary drug resistance
If DRTB is caught from someone who has had previous treatment
What is the treatment regimen for TB?
6 months minimum, site dependant
At least 3 abx for 2 months, then 2 abx for 4 months.
In practice start on 4 abx whilst waiting for c&s, if orgs res patient still on adequate treatment.
Pyrazinamide, isoniazid, rifampicin, ethambutol (2 months) then isoniazid and rif for four.
Used in combination to prevent resistance acquiring.
Treatment for meningeal TB.
Quadruple therapy for 2 months, isoniazid and rif for remainder of treatment initially 12 months.
Add glucorticoid equivalent to prednisiolone 20-40mg if on rif; or 10-20mg adults or 1-2mg/kg max 40mg children.
Gradual withdrawal of steroids within 2-3 weeks of starting treatment.
What is MDRTB?
Multi drug resistant TB.
Resistant to isoniazid and Rifampicin at outset of treatment.
What is XDRTB?
Extensively drug resistant TB
Resistant to isoniazid and Rifampicin plus any fluoroquinolone plus at least one of the 3 Injectable 2nd line TB drugs (Capreomycin, kanamycin or Amikacin)
What is TDRTB?
Totally drug resistant TB.
resistant to all 14 known TB drugs.
Reported in media and India.
MDRTB drug treatment ?
At least 5 drugs, one injectable
XDRTB treatment?
At least 6/7 drugs.
First line TB meds injectable.
Different abx groups
Requires extensive sensitivity and susceptibility testing
When should patients with TB/suspected TB b admitted to hospital?
Only if clear clinical or socioeconomic need.
If ill or need clinical support or have issues which make them unable/unreliable to take medications
How should a patient be dealt with in hospital with suspected pulmonary TB?
Isolate in appropriately engineered (airflow/neg pressure) and ventilated room.
If no appropriate room - isolate in side cubicle.
Remain in isolation until 3 early morning sputums = smear negative. (After 2 weeks of treatment pts considered non-Inf)
Inform TB nurses of suspected case.
How should a patient be dealt with in hospital with smear positive pulmonary TB?
Only admit if clear need
Isolate for first two weeks of treatment, unless risk of MDRTB (previously treated)
Patient should wear a mask whenever they leave their room for the first two weeks of treatment
Inform TB nurses of confirmed case.
What actions should be taken for someone with smear negative pulmonary TB/other sites in hospital ?
Isolation not necessary
Inform TB nurses of admission
Ways in which TB is prevented?
Contact tracing
New entrant screening (born in country >40/100000 cases) - poor
Vaccination of high risk groups - parent/parent in HR country, new entrants, contacts, HCWs, vet care, travelling to HR countries
Chemoprophylaxis for TB contacts
Mop up at key stages of development
Who is contact traced for a person who is smear negative?
Household contacts only i.e. Shares lounge, bedroom, bathroom or kitchen - family, students, some cultures were women have 7/days a week contact
Who is contact traced for a person who is smear positive?
Anyone who has regular contact I.e. 8 hours cumulative over 3 months with contact.
Work environment, household, schools teachers and pupils.
If people are immunosuppressed then they should be traced if less than 8 hours contact.
How is primary school contact tracing performed if someone is smear positive?
Screen whole school and close contacts of adults and children
How is contact tracing performed in secondary school if someone is smear positive?
Look at year only of contact -> if high incidence = screen years above and below.
What screening tests are carried out as part of contact tracing?
Mantoux, chest x Ray and IGRA testing
Screening/treatment process for children aged 4 weeks - 2 years.
Contact with smear +ve TB:
-ve mantoux > chemoprophylaxis for 6 weeks
Repeat mantoux:
-ve > given BCG
+ve > assess for disease and either complete chemoprophylaxis or if disease then complete full 6 months of treatment
What screening is required if TB diagnosed after a shortfall flight?
No action unless immunosuppressed patients on flight
What screening is required if TB diagnosed after long hall flight?
> 8 hours = screen 2 rows either side of case.
Percentage transmission of cattle to human TB?
1%
What is done to prevent cattle to humanTB transmission?
Pasteurisation of milk
Screening cows
Badger culling
Hospital contact tracing of patient with TB
Inform patients who have shared same bay or close beds
Inform patients GP and consultant
Hospital staff member with TB contacting tracing
Same as household screening plus anyone in hospital who has had >8 hours contact or who is vulnerable
MDT with HPA, Hhospital ICN,
Steps in hospital contact tracing
Liase with ICN - list of people who need to be informed
Assess infectivity of case - length of exposure; susceptibility of other patients; proximity of contact (unless sign exp or suscep)
Inform patient
Record in cases notes
Inform GP
What is LTBI?
Latent TB INFECTION
Infected with m, tb but no active disease
How is TB usually diagnosed?
Found through screening contact or new arrival screening
Who is treated for LTBI and what treatments is given??
Individuals under 35 or HCWs of any age
12 weeks of Rifampicin and isoniazid
What is DOTS?
Directly observed therapy
Package of interventions designed to improve management of TB and adherence with treatment
When are DOTS instigated?
If unable to complete treatment due to drug/alcohol or abuse, homeless, chaotic lifestyle
Or if not being compliant during treatment / there are concerns about compliance
What other actions are taken or services are provided to increase TB treatment compliance?
Rehousing
Food vouchers
Travel to hospital
Social issues to help people help themselves
How do TB or HC workers self protect?
BCG
Awareness if signs and symptoms
Personal screening dependant on contact
