TB Flashcards
caused by
mycobacterium tuberculosis
what type of bacteria is mycobacterium tuberculosis
acid-fast bacilli
- rod shaped
- resistant to gram staining = acid-fast
staining technique required
zeihl-neelsen stain
turns TB bacteria bright red against a blue background
active TB
active infection within body
in majority of cases the immune system is able to kill and clear the infection
latent TB
immune system encapsulates sites of infection to stop disease progression
secondary TB
when latent TB reactivates
miliary TB
when immunue system is unable to control disease
–> disseminated, severe disease
why is lungs most common site
most oxygen
risk factors
known contact with active TB
immigrants from high prevalence areas
those with relatives from countries high rate TB
immunosuppressed - HIV, immunosuppressant drugs
homeless people
drug users
alcoholics
BCG vaccine
liver attenuated vaccine
mantoux text done before and vaccine only given if this is negative
who is offered BCG vaccine
neonate born in area of UK with high rate TB
neonate with relatives from country high rate
neonate with FHx TB
unvacc older kids/young adults who are close contact
unvacc immigrants frmo country high rate
healthcare workers
symptoms onset….
chronic, gradually worsening symptoms
signs and symptoms
lethargy fever night sweats weight loss cough +/- haemoptysis lymphadenopathy erythema nodosum
spinal TB aka
pott’s disease of the spine
Mantoux test
indicates prev vaccination, latent TB or active TB
tuberculin injected into forearm and checked 72hrs after
if induration ≥5mm = +ve result
positive result should then be assessed for active disease
interferon-gamma release assays
blood sample mixed with antigens from TB bacteria
if WCC release interferon gamma (indicated prev sensitiation) then positive result
interferon-gamma release assays - when used
patients that do not have features of active TB but do have positive mantoux test
to confirm diagnosis fo latent TB
CXR - primary TB
patchy consolidation
pleural effusion
hilar lymphadenopathy
CXR - reactivated TB
patchy or nodular consolidation with cavitation (gas filled spaces in lungs)
typically upper zones
CXR - disseminated miliary TB
picture of millet seeds uniformly distributed throughout lung feilds
collecting cultures
sputum
mycobacterium blood culture
lymph node aspiration/biopsy
Mx latent TB : otherwise healthy
no not necessarily need treatment
Mx latent TB : risk o f reactivation
isoniazid + rifampicin 3mo
or
isoniazid for 6mo
Mx acute pulmonary TB
Rifampicin 6mo
Isoniazid 6mo
Pyrazinamide 2mo
Ethambutol 2mo
what needs to be prescribed alongside isoniazid and why
isoniazid caused peripheral neuropathy
pyridoxine (vit B6) is usually co-prescribed prophylactically to help prevent this
other Mx considerations
test for other infectious diseases
notify public health
isolate 2wks until 2wks Rx
test contacts
side effects: rifampicin
orange bodily fluids
enzyme inducer - important for COCP
side effects: isoniazid
peripheral neuropahy
- prescribe pyridoxine alongside
side effects: pyrazinamide
hyperuricaemia –> gout
side effects: ethambutol
colour blindness
reduced visual acuity
which drugs are assoc with hepatociity
rifampicin
isoniazid
pyrazinamide
