Chronic Rhinosinusitis

• Refer to Otolaryngology.
• Antimicrobials alone are often not effective.

Pathogens

• Common: anaerobes, streptococci, S. aureus
• Other: Gram-negative bacilli, P. aeruginosa

Drug Treatment

• Duration: Usually at least 14 days.

Organisms with decreased penicillin susceptibility

Consult Infection Diseases/Clinical Microbiology

Empiric

amoxicillin+clavulanic acid HMLSchedNZFPMLnoids Amoxicillin+Clavulanic Acid F: 0.9 / 0.5 Half life: 2 hours / 1 hour Elimination: renal fe: 0.9 / 0.5

PO 500 mg/125 mg three times a day

• fe (amoxicillin) = 0.9, fe (clavulanic acid) = 0.5, consider adjusting dose if CrCl reduced.

Penicillin allergy

doxycycline HMLSchedNZFPML Doxazosin F: 0.7 Half life: 12 hours Elimination: CYP3A fe: 0.1

PO 200 mg on day 1 then 100 mg once a day

• Avoid in pregnancy and breastfeeding.
• Metabolised by unknown pathways. (fe = 0.4).

OR

roxithromycin HMLSchedNZFPML Roxithromycin F: 0.8 Half life: 12 hours Elimination: CYP3A fe: 0.1

PO 300 mg once a day

• If pregnant, consider erythromycin instead of roxithromycin as there are less safety in pregnancy data available for roxithromycin.
• Metabolised by and inhibits CYP3A. (fe < 0.1).
• Subject to P-glycoprotein inhibition and induction.

Pathogens Known

P. aeruginosa

ciprofloxacin HMLSchedNZFPMLnoids Ciprofloxacin F: 0.7 Half life: 4 hours Elimination: renal fe: 0.5 Additional points: Inhibits CYP1A2 and 3A. Antacids, milk, and enteral feeds ↓ absorption.

PO 750 mg twice a day

• fe = 0.5, consider adjusting dose if CrCl reduced.
• Inhibits CYP1A2 (strong) and 3A.
• Subject to OAT and OATP (transporter) inhibition.
• Avoid in pregnancy and breastfeeding.

S. aureus

flucloxacillin HMLSchedNZFPMLnoids Flucloxacillin F: 0.9 Half life: 1 hour Elimination: renal fe: 0.7

PO 500 mg four times a day

• fe = 0.7, consider adjusting dose if CrCl reduced.
• Risk of hepatotoxicity is increased in females, patients > 55 years old, high doses, and courses longer than 14 days duration.

Topic Code: 99227

must be prescribed or recommended by a consultant.