PHARM: Pulmonary Antimicrobials

Question 1

MIND ME antimicrobial creed

Answer 1

• Microbiology-guided therapy (knowing the pathogen first)
• Indications are evidence based
• Narrowest spectrum possible
• Dosage personalised to Pt
• Minimise duration of therapy
• Ensure oral therapy when appropriate

Question 2

Tx for ACUTE rhinosinusitis
- what happens if it lasts >7 days?

Answer 2

• symptomatic Tx: paracetamol, NSAIDs, degongestants (a-agonists)
• if Sx persist for 7 days and include persistent high fever (>39˚ for >3 days), unilateral maxillary sinus tenderness or purulent nasal discharge, give antibiotic (amoxicillin OR cefuroxime/doxycycline)

Question 3

Tx for CHRONIC rhinosinusitis

Answer 3

• treat the CAUSE, not Sx
• if due to inflammation = nasal or oral corticosteroid
• if pus is seen on nasal endoscopy - antibiotic (amoxicillin, cefuroxime, doxycycline)

Question 4

penicillin
- class
- MOA
- AEs
- indications
- is it safe for pregnant women
- what to do if inadequate response
- e.g.

Answer 4

• B-lactams (bactericidal - gram +ve)
• MOA: irreversibly inhibits transpeptidases which facilitate cross-linking and strengthening of peptidoglycan cell wall = cell lysis
• AEs: generally well tolerated but GIT issues, allergies, superinfection
• indicated for URTIs
• safe for pregnant and breastfeeding women
• combine with clavulanic acid if inadequate response in 2-3 days
• e.g. amoxicillin

Question 5

function of clavulanate

Answer 5

• some bacteria have B-lactamase which cleaves B-lactams (penicillins)
• clavulanate inhibits B-lactamase = increased spectrum of antibiotic

Question 6

cephalosporins
- class
- MOA
- indication
- adverse effects
- e.g.

Answer 6

• B-lactams (bactericidal against gram +ve and -ve)
• MOA: irreversibly inhibits transpeptidases which facilitate cross-linking and strengthening of the cell wall, effective against B-lactamase producing bacteria
• indicated if penicillin-sensitive
• AEs: GIT issues (‘lex’ sounds like laxative), neurotoxicity (rare)
• e.g. cephalexin, cefuroxime

Question 7

tetracycline
- MOA
- indication
- AEs
- contraindications
- e.g.

Answer 7

• MOA: reversibly binds to 30s ribosomal subunit, preventing protein synthesis
• indication: if sensitive to penicillin
• AEs: chelates (depletes) Ca2+, teeth discolouration, decreased bone growth in children under 8, photosensitivity, nephrotoxic, hepatotoxic
• contraindications: children younger than 8 and pregnant women after 18 weeks
• e.g. doxycycline

Question 8

antibiotics for pharyngitis (if GABHS)

Answer 8

• highly susceptible to penicillins = narrow spectrum penicillin
• if sensitive: cephalosporin or macrolide

Question 9

macrolides:
- MOA
- AEs
- indication
- e.g.

Answer 9

• MOA: reversibly binds to 50s ribosomal subunit = inhibits bacterial translation
• AEs: cardiotoxic (arrhythmias), hepatotoxic, GIT issues
• indications: mostly gram +ve bacteria - alternative for penicillin sensitivity, indicated in URTIs and whooping cough
• e.g. erythromycin, azithromycin

Question 10

when do you give antibiotics for whooping cough?

Answer 10

• ONLY in the catarrhal stage - almost no bacteria left in the paroxysmal or convalescent stage so not effective

Question 11

factors to consider when thinking abt antibiotics for otitis media

Answer 11

• usually works well - decreased complications e.g. contralateral infection due to vomiting etc
• BUT in children can lead to vomiting, diarrhoea, rash
• recommended for ATSI or immunocompromised

Question 12

antibiotics for otitis media

Answer 12

• treat Sx first
• amoxicillin (1st line) or cefuroxime if sensitive

Question 13

Tx for bronchitis

Answer 13

• if viral: symptomatic
• if bacterial (B. pertussis) suspected: macrolides

Question 14

Tx for influenza

Answer 14

• if otherwise healthy, symptomatic Tx - paracetamol
• if high risk (e.g. healthcare worker, immunocompromised): antiviral - oseltamivir

Question 15

oseltamivir
- MOA
- adverse effects
- indication

Answer 15

• MOA: neuraminidase inhibitor, preventing influenza release from cell
• need to be taken within 48 hrs of Sx and only reduce duration of disease by 1 day
• adverse effects: GIT issues
• indication: influenza Tx and prophylaxis

Question 16

empirical treatment for LOW SEVERITY community-acquired pneumonia

Answer 16

• monotherapy: amoxicillin (1st line), doxycycline or clarithromycin if sensitive OR if atypical pathogen
• combination therapy: doxycycline + amoxicillin or cefuroxime

Question 17

empirical treatment for MODERATE and HIGH SEVERITY community-acquired pneumonia

Answer 17

• moderate: benzylpenicillin + doxycycline OR clarithromycin
• high: ceftriaxone + azithromycin

Question 18

tuberculosis Tx

Answer 18

• RIPE
• rifampicin (1st line w/ isoniazid) - inhibits RNA polymerase
• isoniazid (1st line w/ rifampicin) - inhibits mycolic acid synthesis
• pyrazinamide - mycolic acid
• ethambutol - mycolic acid

Question 19

precautions + AEs when using rifampicin

Answer 19

• significant drug interactions (CYP inducer = increased metabolism of other drugs)
• can’t be used on its own otherwise resistance > combination therapy w/ isoniazid
• AEs: turns secretions orange and yellow

Question 20

precautions and adverse effects when using isoniazid

Answer 20

• can’t be used on its own otherwise resistance > combination therapy w/ rifampicin
• AEs: allergic skin reactions, fever, hepatotoxic, haematological changes

Question 21

pyrazinamide
- optimal pH
- AEs

Answer 21

• works at acidic pH (when bacteria are contained in macrophages)
• AEs: increased risk of gout, GIT issues, malaise, fever, hepatotoxic

Question 22

ethambutol AE

Answer 22

• dose-related optic neuritis