Antibiotics for infections: Longer course not necessarily better

When it comes to treating infections and reducing related hospitalizations, shorter antibiotic courses are just as effective as longer ones, according to a study conducted in the UK, where prescribing trends indicate an increase in long courses and a decline in short courses.

“The findings in this study support previous research [showing] no additional benefit in prescribing longer antibiotic courses compared to shorter antibiotic courses when treating a variety of acute infectious conditions,” as pointed out by researchers from the University of Manchester, UK. [JAMA Intern Med 2016;176:1254-1255; BMJ 2017;358:j3418; J Hosp Med 2018;13:336-342; Fam Pract 2017;34:511-519]

“Current recommendations do not inform physicians of the best treatment for re-occurring infections, except for urinary tract infections (UTIs), nor do they consider a patient’s historic antibiotic exposure … all of which may affect the success of the subsequent antibiotic treatment,” they said. “The physician is left to prescribe empirically [according to the] patients' history with limited trial data to inform guidance for complex prior exposures.”

The current analysis was based on more than 4 million acute infection-related consultations in primary care that resulted in antibiotic prescriptions—59.1 percent for upper respiratory tract infections (URTIs), 24.6 percent for lower respiratory tract infections (LRTIs), and 16.3 percent for UTIs.

Over a 15-year period (2000–2014), prescriptions for 6–7- and 8–14-day courses rose by 19.1 percent and 5.2 percent, respectively, but that for a 5-day course dropped by 24.2 percent. The most prescribed duration was 6–7 days (62.43 percent). [Clin Infect Dis 2021;doi:10.1093/cid/ciab159]

The overall incidence rate of infection-related hospitalizations was 0.15 percent, with the majority of cases occurring among patients who received an antibiotic course of 8-15 days overall (0.21 percent) and for LRTIs (0.39 percent).

Frequently prescribed agents were amoxicillin for RTIs and trimethoprim for UTIs. Meanwhile, phenoxymethylpenicillin (penicillin V) or doxycycline were most often issued for 8–15-day courses and as an oral suspension.

In multivariable Cox models, long versus short antibiotic courses conferred a greater risk of infection-related complications overall within 5 days of follow-up (6–7 days: hazard ratio [HR], 1.40, 95 percent confidence interval [CI], 1.29–1.52; 8–15 days: HR, 1.74, 95 percent CI, 1.52–1.99) and within 6–30 days of follow-up (6–7 days: HR, 1.32, 95 percent CI, 1.20–1.45; 8–15 days: HR, 1.60, 95 percent CI, 1.37–1.87).

When estimates in the first 5 days and the remaining follow-up were compared, longer antibiotic courses were no more effective than shorter courses (HR, 1.02, 95 percent CI, 0.90–1.16 and HR, 0.92, 95 percent CI, 0.75–1.12). Results did not vary when stratified by infection type.

Recent evidence suggest that many antibiotics are prescribed for longer than guidelines recommend, mostly because of dated ideas implemented when there was little concern about antibiotic overuse, the researchers noted.

“It was taught that to prevent reinfection and reduce resistance, it is necessary for patients to complete the entire course of antibiotics even when symptoms have surpassed, and that prolonged therapy was needed to avoid treatment failure suggesting that shorter antibiotic courses were perceived as an inferior treatment to longer courses,” they said. [JAMA Intern Med 2016;176:1254-1255; BMJ 2017;358:j3418]

“Furthermore, some prescribers feel more comfortable selecting a middle-range duration, or in some cases, the longest duration specified, even if the intention of the specified range is that the shortest duration is adequate for most patients,” they added. [J Antimicrob Chemother 2018;73:1084-1090]

As such, the researchers called for additional investigation to determine the most effective strategies for optimizing duration of antibiotic treatment for individual patients. A combination of patient characteristics, clinical presentation, symptom severity, and prior antibiotic use should help pinpoint those who are more at risk of failing to recover on shorter antibiotic courses.