Efficacy and safety of antibiotic treatment in relation to treatment time

Decisions on treatment times with antibiotics are often arbitrary and based on empirical decisions or clinical trials which are too small to exclude even considerable differences between two study groups. Single-dose treatment of uncomplicated cystitis in women has been advocated by many but a careful analysis of available information clearly shows that a single-dose has so far always been inferior to 3-day or greater than 5-day treatment. With trimethoprim-sulphonamide combinations, no further efficacy is gained by increasing the treatment time in uncomplicated cystitis above three days while frequency of side effects increases drastically with extended treatment. In contrast, treatment with beta-lactams, for less than five days seems to result in unacceptable failure rates. In pyelonephritis there are few studies of the efficacy of antibiotic treatment for less than ten days. A comparison of two and six weeks' treatment showed no advantages with the extended time. There has also been a tendency towards reduced treatment times in upper respiratory tract infections such as streptococcal pharyngotonsillitis. However, two studies comparing 10-day treatment to 7-day and 5-day treatments, respectively, have clearly shown that the shorter treatment times give much higher rates of both clinical and bacteriological relapse. In more severe infections such as meningitis, no studies comparing treatment times have been carried out. It seems possible to use treatment for five days or less in meningococcal meningitis while other pathogens should be treated for ten days or longer. In endocarditis, the treatment time must vary with causative pathogens and can only rarely be shorter than four weeks.(ABSTRACT TRUNCATED AT 250 WORDS)