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Block 31 Cardio-respiratory > Tuberculosis > Flashcards

Tuberculosis Flashcards

1
Q

describe the basic epidemiology of tuberculosis?

A
  • 1/3 of worlds population are infected with TB
  • 9 million new and relapsed cases
  • 1.4 million deaths
  • incidence increased by 1% each year and peaked in 2005 and now is declining
  • mainly Africa and Asia
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2
Q

what are the 4 main mycobacterial species which are collectively known as mycobacterium tuberculosis complex?

A

Mycobacterium tuberculosis
Mycobacterium bovis
Mycobacterium africanum
Mycobacterium microti

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3
Q

describe the characteristics of mycobacterial species?

A

obligate aerobes and faculative intracellular pathogens, usually infecting mononuclear phagocytes.
slow growing generation time of 12-18 hours
high lipid content in the cell wall so relatively impearmeable
acid fast bacilli

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4
Q

describe the basic pathogenesis of tuberculosis?

A

-airborne
-respiratory droplets
-only small number of bacteria need to be inhaled to develop infection but not all those who are infected develop active disease
the outcome of exposure is dictated by a number of factors including the hosts immune response

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5
Q

describe primary tuberculosis infection?

A
  • infection with MTb
  • alveolar macrophages ingest bacteria
  • bacilli proliferate in macrophage
  • release of neutrophils, chemoattractants and cytokines
  • leads to inflammatory cell infiltrate reaching lung and draining hilar lymph nodes
  • macrophages present antigen to T cells
  • development of celular immune response
  • delayed hypersensitivity type reaction leading to tissue necrosis and formulation of a granuloma
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6
Q

what is a granulomatous lesion?

A

central area of necrotic material (caseation) surrounded by epitheliood cells and langhans’ giant cells
caseated areas heal and may become calcified some contain bacteria that can lay dormant for year

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7
Q

what is a ghon focus?

A

the inital focus of disease

on x-ray is a small calcified nodule in upper parts of lower lobes or lower parts of upper lobes

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8
Q

what is a primary complex of ranke?

A

a ghon focus that may develop in a regional draining lymph node

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9
Q

what percentage of people develop active disease upon initial contact with infection?

A

<5%

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10
Q

what is latent TB?

A

For most people infected with mycobacterium, the immune system contains the infection and the patient develops cell mediated immune memory to the bacteria called latent TB

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11
Q

what are the features of latent infection?

A 
bacilli present in ghon focus
sputum smear and culture negative
tuberculin skin test usually positive
chest x-ray normal (small calcified ghon focus frequently visible)
asymptomatic
not infectious to others
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12
Q

what are the features of active disease?

A

-bacilli present in tissues or secretions
-sputum commonly smear and culture positive in pulmonary disease
MTb can usually be cultured from infected tissue
tuberculin skin test usually positive (and can ulcerate)
chest X-ray signs of consolidation /cavitation/effusion in pulmonary disease
symptomatic (night sweats, fevers, weight loss, cough)
infectious to others if bacilli detectable on sputum

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13
Q

what factors are implicated in the reactivation of latent TB?

A 
HIV co-infection
immunosuppresant therapy
diabetes mellitus
end stage chronic kidney disease
malnutrition
ageing
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14
Q

what are the clinical features of pulmonary TB?

A

Symptomatic with a productive cough and occasionally haemoptysis along with systemic symptoms of weight loss, fevers and sweats (commonly at the end of the day and at night). When there is laryngeal involvement, hoarse voice and a severe cough are found. If disease involves pleura the pleuritic pain may be the presenting complaint

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15
Q

how is a diagnosis of pulmonary TB made?

A

Chest X-ray-consolidation with or without cavitation, pleural effusion or thickening or widening of the mediastinum caused by hilar or paratracheal adenopathy

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16
Q

what are the clinical features of lymph node TB?

A

extrathoracic nodes are more commonly involved and usually presents as a firm non tender enlargement of a cervical or supraclavicular node. Node becomes necrotic centrally and can liquefy and be fluctuant if peripheral. Overlying skin is frequently indurated or there can be sinus tract formation with purulent discharge but characteristically there is no erythema. Nodes can be enlarged for several months before diagnosis. On CT, the central area appears necrotic

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17
Q

what would be appropriate diagnostic investigations for a patient with pulmonary, pleural or laryngeal TB?

A

smear and culture of

  • sputum
  • bronchoalveolar lavage if unproductive cough
  • aspiration of pleural fluid and pleural biopsy
  • nasoendoscopic or bronchoscopic examinations/biopsy
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18
Q

what would be the appropriate diagnostic investigations and findings in a patient with miliary TB?

A
  • blood cultures
  • bronchoalveolar lavage (smear negative but culture positive)
  • lumbar puncture-assess CNS involvement
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19
Q

what would be the appropriate diagnostic investigations and findings in a patient with CNS TB?

A
  • lumbar puncture (CSF protein high, CSF glucose <1/2 blood glucose
  • CSF lymphocytosis
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20
Q

what would be the appropriate diagnostic investigations and findings in a patient with lymph node TB?

A
  • all samples sent for histocytopathological examination

- culture and smear (fine needle aspiration or biopsy of involved lymph / mediastinal nodal sampling)

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21
Q

what microbiological methods are used to make a diagnosis of TB?

A
  • stains
  • culture
  • nucleic acid amplification
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22
Q

describe the use of stains in making a diagnosis of TB?

A

auramine-rhodamine staining is more sensitive (but less specific) than ziehl-neelsen so is more widely used)
bacilli are highlighted as yellow/orange on a green background

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23
Q

describe the use of culture in making a diagnosis of TB?

A

liquid culture

allows detection of drug sensitivity to infection

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24
Q

describe the use of nucleic acid amplification in making a diagnosis of TB?

A

used to differentiate between mycobacterium and non-mycobacteria

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25
Q

what is directly observed therapy?

A

widely recommended and employed with an aim to achieve treatment completion
it is treatment supervised by a healthcare professional where the patient is observed swallowing the medication

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26
Q

what is the criteria for the implementation of directly observed therapy?

A
  • patients thought unlikely to comply such as patients with serious mental health problems or with a history of TB non-adherence
  • street or shelter dwelling homelessness
  • multi-drug resistant TB
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27
Q

what is the usual duration of treatment for pulmonary, extrapulmonary or miliary TB?

A

6 months
can be extended to 9 months in certain situations
-patient smear positive 2 months into treatment
-HIV co-infection
-high burden of disease

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28
Q

what is the drug choice for TB treatment?

A

2 months of rifampicin, ethambutol, isoniazid, pyrazinamide plus 4 months of isoniazid and rifampicin

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29
Q

what are the basic steps in treatment once a patient has been diagnosed with TB?

A
  • allocate case manager
  • health and social care plan
  • drug treatment
  • address housing needs
  • strategies to encourage adherence
  • directly observed therapy needed?
  • surgery needed?
  • follow up
30
Q

what drugs are used for treatment of active TB of CNS?

A
  • isoniazid (+pyridoxine), rifampicin, pyrazinamide, ethambutol for 2 months
  • isoniazid (+pyridoxine) and rifampicin for 10 months
31
Q

describe drug resistance in TB treatment?

A
  • due to incomplete or incorrect drug treatment and can be spread from person to person
  • multi drug resistance (rifampicin and izoniazind) is low
  • mono resistance is fairly common-10% in UK
32
Q

what is the treatment for isoniazid resistant TB?

A

2 months- rifampicin, pyrazinamide and ethambutol

7 months - rifampicin and ethambutol

33
Q

what is the treatment for pyrazinamide resistant TB?

A

2 months-rifampicin, isoniazid (with pyridoxine) and ethambutol and ethambutol
7 months-rifampicin, isoniazid (with pyridoxine)

34
Q

what is the treatment for ethambutol resistant TB?

A

2 months-rifampicin, isoniazid (with peridoxine) and pyrazinamide
4 months-rifampicin and isoniazid (with pyridoxine)

35
Q

what is the treatment for rifampicin resistant TB

A

same as treatment for multidrug resistant TB

36
Q

what methods can be taken to control spread of TB?

A
  • contact tracing
  • screen healthcare workers
  • screen new entrants to the country, homeless, hostel dwellers, immunocompromised people, BCG vaccination
37
Q

what is a classic presentation of pneumonia?

A 
shaking chills
purulent sputum
bacteremia
acute cough
breathlessness
fever
38
Q

describe pulmonary infarction?

A

occurs when artery to lung becomes blocked and part of the lung dies
most often caused by pulmonary embolism

39
Q

what are the clinical features of pulmonary infarction?

A

Angiographic demonstration of pulmonary thromboemboli
Concurrent condition frequently predisposing to pulmonary thromboembolism. Bloody, non purulent sputum, sanguineous pleural effusion, migratory parenchymal infiltrates and unresponsive to chemotherapy.
Do not dismiss infarction simply due to high fever, leucocytosis, normal JVP, atypical pulmonary lesions, non bloody pleural effusion, failure to detect the source of emboli, or because patient is young or appears healthy

40
Q

describe pnuemonia?

A
  • inflammation of lung
  • usually bacterial cause
  • 50% is pneumococcal
  • classified by setting is which person contracted their infection
41
Q

what is the commonest cause of community acquired pneumonia?

A

pneumococcus (streptococcus pneumonia)

42
Q

what part of the lungs does community acquired pneumonia affect?

A

localised with one or more lobes affected (Lobar pneumonia) or diffuse where lobules of lung are mainly affected often due to pneumonia centred on bronchi and bronchioles

43
Q

how is pneumonia infection spread?

A

respiratory droplets

44
Q

what are the clinical features of community acquired pneumonia?

A
  • cough (dry or productive and hemoptysis, rust coloured sputum),
  • breathlessness (alveoli filled with pus and impair gas exchange, course crackles , bronchial breath sounds)
  • fever
  • chest pain (pleuritic, may hear plural rub)
  • extrapulmonary features
  • other features (confusion or nonspecific symptoms)
45
Q

what investigations are needed in community acquired pneumonia?

A
  • microbiological tests not needed in mild infection
  • CXR if mild disease doesn’t improve in 48-72 hours
  • CURB-65
  • if admitted to hospital - CXR, bloods, microbiological tests and repeat CXR 6 weeks after discharge
46
Q

how is mild pneumonia treated?

A 
oral amoxicillin 500mg 3x day
OR
oral clarithromycin 500mg 2x daily
OR
doxycycline 100mg daily
47
Q

what are the radiological findings of strep. pneumonia?

A

consolidation with air bronchograms, effusion and collapse due to retention of secretions
radiological abnormalities lag behind clinical signs

48
Q

what are the radiological findings of mycoplasma pneumonia?

A

usually one lobe affected but infection can be bilateral and extensive

49
Q

what are the radiological findings of legionella pneumonia?

A

lobar and multi lobar shadowing, with occasional small pleural effusion
cavitation is rare

50
Q

what makes up the CURB65 score?

A

Confusion
Urea level >7mmol/L
respiratory rate >30
BP S<90, D<60

51
Q

what implication does CURB 65 score have on management?

A 
0-1 = outpatient treatment
2 = admit to hospital
3+ = ICU care
52
Q

what blood tests are performed in patients with pneumonia?

A

FBC
urea and electrolytes
biochemistry
CRP

53
Q

what blood results would be expected in a patient with strep pneumonia?

A

WCC >15=10^9

inflammatory markers raised

54
Q

what would WCC be in a patient with mycoplasma pneumonia?

A

normal WCC

55
Q

what blood result would you expect in a patient with legionella pneumonia?

A

lymphopenia without marked leucocytosis
hyponatraemia
hypoalbuminaemia
high serum levels or liver aminotransferases

56
Q

what investigations should be performed if a patient has a CURB65 score of 2?

A
  • blood cultures
  • sputum
  • pneumococcal antigen
  • serology or PCR if epidemic
57
Q

what treatment is given to a patient if they have a CURB65 score of 2?

A

amoxycillin 500-1000mg 3x daily + clarithromycin 500mg 2x daily
if penicillin allergy:
doxycycline 100mg daily with 200mg loading dose
or levofloxacin 500mg 2x daily
or moxifloxacin 400mg daily orally

58
Q

what investigations are performed in a patient with CURB65 of 3-5?

A 
blood culture
sputum
pneumococcal antigen
legionella antigen
serology and viral PCR
59
Q

what treatment is given to a patient with a CURB65 score of 3-5?

A

-antibiotics ASAP
-co-amoxiclav 1.2g 3x daily IV + clarithromycin 500mg 2x daily IV (fluoroguinolone if suspect legionella suspected)
OR
penicillin allergy
-IV cephalosporin +clarithromycin
-benzylpenicilin 4x daily or 4 hourly + fluoroquinolone

60
Q

what are some of the complications of pneumonia?

A 
respiratory failure
sepsis
pleural effusion
emphyema
lung abscess
organising pneumonia
61
Q

what is hospital acquired pneumonia?

A

new onset of cough with purulent sputum with compatible X-ray demonstrating consolidation in patients who have been more than 2 days in hospital or been in healthcare setting within last 3 months

62
Q

what organisms are commonly implicated in hospital acquired pneumonia?

A 
gram negative bacilli 
P.aeruginosa
E.coli
klebsiella pneumoniae
acinetobacter
MRSA
63
Q

What bacteria are usually implicated in pneumonia acquired in nursing homes?

A

gram negative rods
pneumococcus
pseudomonas

64
Q

what are the clinical features of streptococcus pneumoniae?

A 
acute onet
preceded by flu like symptoms
cough with rust coloured sputum
high fevers
pleuritic chest pain
bacteraemia more common in women, excess alcohol, dry cough and COPD, diabetes or HIV infection
65
Q

what are the clinical features of mycoplasma pneumoniae?

A

usually mild disease in young patient
occurs in cycles every 3-4 years
prominent extrapulmonary symptoms
common complications

66
Q

what are the clinical features of legionella spp. pneumonia?

A

causes more severe disease with intensive care needed
acquired by inhaling water mist containing bacteria
neurological symptoms with GI involvement
more common in smokers, men and young people

67
Q

what are the clinical features of pneumonia caused by staphylococcus aureus?

A

recent influenza in 40-50%

MSSA which can result in necrotising cavitating pneumonia and bilateral infiltrates

68
Q

what are the clinical features of chlamydophila pneumoniae?

A

unclear whether causative or associated organism

causes mild disease but with prolonged prodrome

69
Q

what are the clinical features of haemophilus influenza pneumonia?

A

more common in pre-existing structural lung disease (CF, bronchiectasis, COPD) and elderly

70
Q

what is involved in the management of pneumonia?

A 
oxygen between 94-98%
IV fluids
antibiotics
thromboprophylaxis
physiotherapy 
nutritional supplementation
analgesia

Block 31 Cardio-respiratory (15 decks)

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