Final answer:
The first-line therapy for the treatment of acute sinusitis in an adult with no recent antimicrobial use is Amoxicillin-clavulanate. Other antibiotics might be used if there's a history of penicillin allergy or resistance to penicillins.
Step-by-step explanation:
First-Line Therapy for Acute Sinusitis
The first-line therapy for the treatment of acute sinusitis in an adult with no recent antimicrobial use would be Amoxicillin-clavulanate. This is because amoxicillin-clavulanate provides a broad-spectrum coverage that is effective against most of the common bacteria responsible for sinusitis, and the addition of clavulanate helps to overcome bacterial resistance by inhibiting beta-lactamase enzymes.
Other antibiotics such as azithromycin or levofloxacin might be prescribed in cases where there is a history of penicillin allergy, intolerance, or when the bacterial strain is suspected to be resistant to penicillins. However, they are not usually the first choice for uncomplicated acute sinusitis in patients with no recent history of antimicrobial use. Ceftriaxone could be used in severe cases or when parenteral administration is necessary.