Compliance with the national guidelines for the use of antibiotics in hospitals
(4) is key to safe and rational antimicrobial therapy. Our study revealed that the use of ciprofloxacin was unwarranted in 92 % of patients.
Resistance to ciprofloxacin is widespread among microbes
(6). According to the Norwegian Surveillance System for Antimicrobial Drug Resistance (NORM), 11.7 % of blood culture isolates and 9.3 % of urinary isolates of Escherichia coli were resistant to ciprofloxacin in 2018, with the corresponding figures for Klebsiella species being 8.1 % and 6.3 % (3). Epidemiological data on microbial resistance are the cornerstone of empirical therapy recommendations.
Careful consideration of the results of microbiological testing should form the basis for antimicrobial therapy. In our study, we found that the results of microbiological testing were not taken into account in 90 % of cases. In a prospective multicentre study in France, the absence of a clear diagnosis and lack of microbiological sampling were identified as independent risk factors for inappropriate antibiotic use
Up to 10 % of patients are reported to have an antibiotic allergy
(8), in common with 20 % of the patients in our study. This has been shown to lead to increased prescribing of broad-spectrum antibiotics, with adverse consequences (9). The large number of patients reported to have antibiotic allergies is likely to have contributed to the prescription of ciprofloxacin in our study, but this was documented in only half of cases. A realistic estimate for the prevalence of true IgE-mediated antibiotic allergy is probably less than 1 %. Testing for antibiotic allergy is an appropriate strategy for increasing the cure rate with penicillin treatment, and is an effective antimicrobial stewardship intervention (8).
Fluoroquinolones have long been monitored with respect to side effects
(10). In October 2018, health authorities specified that fluoroquinolones should be reserved only for certain specific and serious infections on the basis of new information about irreversible and disabling side effects in the nervous and musculoskeletal systems, as well as the rupture of aortic aneurysms (11).
Taken together, the mechanism of action, side effects, resistance profile and ecological shadow of fluoroquinolones suggest the need for restrictive therapeutic recommendations. The use of ciprofloxacin has halved in Norwegian hospitals in recent years
(1), but our study nevertheless indicates that more than 90 % of usage still falls outside the therapeutic recommendations.
Data from the Norwegian hospital pharmacies' drug statistics database ('SLS') show that in 2018, Norwegian health trusts used an average of 2.28 defined daily doses (DDD) of fluoroquinolones per 100 bed days (95 % confidence interval 2.05–2.51)
(12). This may indicate that our findings have good generalisability.
This study has confirmed that ciprofloxacin is very often used in a manner inconsistent with therapeutic recommendations. We conclude that there is a need for hospital departments to exercise greater restraint in the use of this important class of antibiotics.