Antibiotic for Respiratory Infections

Question 1

URTI examples

Answer 1

• Common cold
• Sinusitis
• Pharyngitis
• Epiglottitis
• Laryngotracheitis

Question 2

URTI etiology

Answer 2

• Mostly viral
• Epiglottitis and laryngotracheitis: Haemophilus influenza type B
• Bacterial pharyngitis: streptococcus pyogenes

Question 3

URTI clinical manifestations

Answer 3

• Cold: runny nose, sneezing, no fever
• Epiglottitis: difficulty in breathing, muffled speech, drooling, stridor
• Larynogetracheitis: tachypnea, stridor, cyanosis

Question 4

LRTI examples

Answer 4

• Pneumonia
• Bronchitis
• Bronchiolitis

Question 5

LRTI aetiology

Answer 5

• Viral or bacterial
• Bronchitis & Bronchiolitis: mostly viral
• CAP: streptococcus pneumoniae
• Atypical pneumonia: mycoplasma pneumoniae, chlamydia spp, legionella, coxiella burnetti, viruses
• HAP: gram-negative organisms (staphylococci as predominant organisms)

Question 6

LRTI clinical manifestations

Answer 6

• Cough, fever, chest pain, tachypnea, sputum production

* Confusion, headache, myalgia

Question 7

Antibacterials types

Answer 7

• Beta-lactam antibiotics
• Macrolides
• Protein synthesis inhibitors
• Others (vancomycin, quinolone)

Question 8

Beta lactam antibiotics examples

Answer 8

• Pencillins
• Cephalosporins
• Carbapenems

Question 9

Protein synthesis inhibitors types

Answer 9

• Tetracycline

* Doxycycline

Question 10

Macrolides example

Answer 10

Erythromycin

Question 11

Beta lactam antibiotics MOA

Answer 11

Inhibit cell wall synthesis (inhibit transpeptidase)

Question 12

Penicillin clinical uses

Answer 12

• Pneumococcal pneumonia/meningitis
• Pharyngitis/recurrent rheumatic fever
• Bronchiolitis

Question 13

Penicillin ADR

Answer 13

• Generally well-tolerated, except hypersensitivity reaction
• Anaphylactic shock
• Serum sickness (urticaria, fever, joint swelling)
• Skin rash (ampicillin)
• Interstitial nephritis
• Diarrhoea & superinfections (ampicillin, amoxicillin)

Question 14

1st generation cephalosporins examples

Answer 14

Parenteral: Cephalothin, cefazolin
Oral: Cephalexin, cefadroxil

Question 15

1st generation cephalosporins clinical use

Answer 15

• Against G+ve bacteria, Proteus, E. coli, Klebsiella (PEcK)
• Cephalexin, cefadroxil: CAP
• Cefazolin: used prior to surgical procedures

Question 16

2nd generation cephalosporins examples

Answer 16

• Parenteral: Cefuroxime

* Oral: Cefaclor

Question 17

2nd generation cephalosporins clinical use

Answer 17

• HENPEcK: H. influenza, Enterobacter aerogenes, Neisseria
• More G-ve coverage
• Esp beta lactamase producing H. influenza
• Less active against G+

Question 18

3rd generation cephalosporins examples

Answer 18

Parenteral: Cefotaxime, ceftriaxone
Oral: Cefixime

Question 19

3rd generation cephalosporins clinical use

Answer 19

• Enhanced activity against Enterobacter spp, serratia

* Cefotaxime, ceftriaxone: CAP

Question 20

4th and 5th generation cephalosporins

Answer 20

4th generation (Parenteral): cefepime, cefpirome 
5th generation: ceftaroline

Question 21

4th and 5th generation cephalosporins clinical use

Answer 21

• More resistant to betalactamases

* For serious G-ve infections: enterobacter, citrobacter, serratia

Question 22

Cephalosporins ADR

Answer 22

• Hypersensitivity reaction: anaphylaxis, fever, skin rashes, nephritis, hemolytic anemia
• Ceftriaxone: biliary sludging syndrome, cholelithiasis

Question 23

Cephalosporins contraindications

Answer 23

Allergy (cross reactivity with penicillins

Question 24

Carbapenems examples

Answer 24

• Imipenem

* Newer agents: Meropenem, Ertapenem

Question 25

Carbapenems properties

Answer 25

* Gram +ve, -ve aerobes, anaerobes * Given by Parenteral route * Rapidly hydrolysed by renal dehydropeptidase - I * Cilastatin - reversible inhibitor of this enzyme

Question 26

Carbapenems clinical use

Answer 26

• Severe hospital acquired infections, LRTI

Question 27

Carbapenems ADR

Answer 27

• Induce seizures at higher doses

Question 28

Protein synthesis inhibitors MOA

Answer 28

Bind to 30S subunit and inhibit tRNA binding to acceptor site

Question 29

Doxycycline indication

Answer 29

* CAP due to S. pneumoniae, H influenza | * mycoplasma, chlamydia

Question 30

Doxycycline adverse effects

Answer 30

* GI: Epigastric burning * Hepatotoxicity, renal toxicity * Fanconi's syndrome with outdated tetracyclines

Question 31

Doxycycline contraindication

Answer 31

Children: discolouration of teeth

Question 32

Macrolides MOA

Answer 32

* Binds to 50S ribosomal subunit | * Inhibits translocation of peptidyl-tRNA

Question 33

Macrolides indication

Answer 33

* Respiratory tract infections due to Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens (mycoplasma, chlamydia, legionella) * Acute exacerbations of chronic bronchitis, acute otitis media, acute streptococcal pharyngitis, and acute bacterial sinusitis

Question 34

Macrolides ADR

Answer 34

* Cholestatic jaundice * GI disturbances: nausea, vomiting, diarrhoea * CVS: QT prolongation, vent arrythmia * Microsomal enzyme inhibition: enhances effect of warfarin, theophylline, digoxin, CCBs

Question 35

Vancomycin MOA

Answer 35

• Inhibit cell wall synthesis by binding with D-alanyl-D-alanine terminus of cell wall precursor units

Question 36

Vancomycin indication

Answer 36

* Pneumonia when MRSA is suspected | * HAP/CAP with risk factors for staphylococcal infection

Question 37

Vancomycin ADR

Answer 37

* Allergy: anaphylaxis, skin rash, urticaria * Skin flushing: red man syndrome * Ototoxicity: hearing impairment * Nephrotoxicity: more with high dose (esp w aminoglycosides)

Question 38

Quinolones MOA

Answer 38

Inhibit formation of negative DNA supercoils by DNA gyrase

Question 39

Quinolones indication

Answer 39

* Respiratory tract infections: Ciprofloxacin * CAP: moxifloxacin * Legionella pneumophila: levofloxacin

Question 40

Quinolones ADR

Answer 40

* GI: mild n/v and abdominal discomfort * tendinitis * Pseudomembranous colitis (Ciprofloxacin)

Question 41

Quinolones CI

Answer 41

• Children: may damage growing cartilage and cause arthropathy

Question 42

Drugs for influenza

Answer 42

* Zanamivir (SE: bronchospasm) | * Oseltamivir (SE: nausea, vomiting)