Lecture 11 - treatment of resp infections

Question 1

Which groups of people are at a higher risk of CAP?

Answer 1

the elderly, males, alcoholics, and those with chronic disease

Question 2

Percentage of CAP caused by conventional bacteria? atypical? virus?

Answer 2

conventional 60-80
atypical 10-20
viruses 10-20

Question 3

What are the two main causes of CAP

Answer 3

S. pneumoniae
H. influenzae

(other ones are pneumonia M C L )

Question 4

Name the 4 steps in the investigation of CAP

Answer 4

confirm the diagnosis, assess the severity of the disease, define the aetiological agent (important when treating) and identify for complications

Question 5

What is antimicrobial management of CAP based on

Answer 5

assessment of likely pathogen
severity of the illness
likelihood of resistance

Question 6

What microbiological investigations can be taken for CAP

Answer 6

sputum analysis and culture
immunoflorescence on sputum samples
blood cultures
urinary pneumococcal legionella antigen

Question 7

What is the criteria for CAP?

Answer 7

Confusion
Urea >7mmol/l
Resp rate over 30
Blood pressure

Question 8

Describe mycoplasma CAP

Answer 8

patchy consolidation on CXR, prominent extra pulmonary disease. more likely in young patients. has prolonged gradual onset

Question 9

What is characteristic of S aureus CAP?

Answer 9

abscess formation on CXR, very aggressive disease increased tissue lysis

Question 10

What is characteristic of legionellosis CAP

Answer 10

hyponatraemia, multi lobe involvement, confusion and neurological symptoms

Question 11

Which two groups in the UK are more likely to have TB

Answer 11

socially disadvantaged and ethnic minority

Question 12

Describe the two phases of TB

Answer 12

Latent phase - where granulomatous forms - controlled by cell mediated response and lays dormant.
Active phase - where disease is reactivated and extracellular growth occurs. bacteria disseminate from granulomatous

Question 13

Which factor keeps TB in latent phase and how

Answer 13

DosR maintains the organism in hypoxic environment inside the granulomatous - ensuring organism homeostasis

Question 14

Name three typical TB CXR appearences

Answer 14

Reactivated TB usually appears in the upper lobes of chest X rays
Reactivated TB in immunocompromised spreads throughout lung
Millary TB is disseminated

Question 15

Which TB drugs are bactericidal

Answer 15

Rifampicin, Isoniazid, Ethambutol (moderate), Streptomycin

Question 16

Side effects of Rifampicin

Answer 16

rash, hepatitis, fever, flu syndrome, drug interactions e.g. pill

Question 17

Side effects of Isoniazid

Answer 17

hepatitis, peripheral neuropathy, cutaneous hypersensitivity

Question 18

Side effects of Pyranzinamide

Answer 18

hepatitis, anorexia, flushing, cutaneous hypersensitivity, hyperuricaemia

Question 19

Side effects of Ethambutol

Answer 19

optic neuritis which can cause blindness - never give to someone who cannot report visual changes e.g. a child

Question 20

Side effects of Streptomycin

Answer 20

ototoxicity (blood levels should be monitored in renal impairment)

Question 21

How do TB drugs work

Answer 21

Rifampicin inhibits RNA polymerase
Ethambutol inhibits synthesis of cell wall polysacherides
Streptomycin binds to mycobacterial ribosome and inhibits protein synthesis

Question 22

What are the principles of chemotherapy for TB

Answer 22

• mycobacteria within an infected individual are in two phases of replication
• the population contains natural occurring resistance

Question 23

Why is TB treated with two phase therapy and combination therapy

Answer 23

2 phase - as bactericidal phase to kill majority of active organisms and sterilising phase which persisting organisms (latent) are eliminated
combination - resistance is frequent- more drugs means less likely to be resistant to all of them (single drug therapy always selects resistant organisms)

Question 24

Why is 6 months required for eradication of TB?

Answer 24

persisting organisms undergo intermittent metabolic activity

Question 25

What is DOT in TB testing?

Answer 25

nurse of surrogate directly observes all doses taken - increases compliance. UK dont do much but do in US

Question 26

Which TB drug has the highest resistance rates?

Answer 26

isoniazid

Question 27

Which patients are more likely to have acquired a MDR TB? (5)

Answer 27

• if the individual has previously been treated for TB
• contact with known MDR TB case
• got infection in country with high prevalence of MDR TB
• patients dont respond to treatment
• co-existing HIV

Question 28

How is MDR TB managed?

Answer 28

• initial treatment should be with at least 4 TB drugs the organism is sensitive to and should last 3-6 months PAST the sputum becomes culture negative
• the second phase should be continued with 3 drugs for 15-18 months

Question 29

What else must be done if a patient is found to have MDR TB?

Answer 29

notifying TRACE
infection control measures
BCD