Comparison of cyclacillin and amoxicillin for therapy for acute maxillary sinusitis.

Cyclacillin, a new aminosalicylic semisynthetic penicillin, was compared with amoxicillin for the therapy of acute bacterial maxillary sinusitis in 80 patients (ages, 12 to 70 years) in a prospective, double-blind, randomized clinical trial. Direct sinus aspirations for quantitative culture were done for all patients before and after 10 days of therapy. Both drugs were administered at a dosage of 500 mg orally three times daily. Among culture-positive patients, clinical cure was achieved in 23 of 26 patients and 25 of 27 patients treated with cyclacillin and amoxicillin, respectively, for an overall cure rate of 91%. Bacteriologic failure occurred in 9% (4 of 44 patients); 3 of the 4 failures were in the cyclacillin group. There was no correlation between clinical or bacteriologic cure and the results of sinus transillumination (clear, dark) at follow-up. Initial direct sinus aspirates were positive in 57 of 80 cases (70%): 25 (44%) of these were the result of Streptococcus pneumoniae and 23 (40%) were the result of Haemophilus influenzae. All of these isolates were susceptible (MIC, less than or equal to 0.5 microgram/ml) to both study drugs; no ampicillin-resistant H. influenzae was recovered. On day 10 of therapy, mean concentrations of both drugs in serum were 2.5 to 2.7 micrograms/ml, but no antibiotic was detectable in 20 of 21 simultaneous sinus aspirates. Adverse effects (rash, diarrhea) were infrequent and similar in both groups. Cyclacillin appears equivalent to amoxicillin in the therapy of acute maxillary sinusitis.