Duration of antibiotic treatment: are even numbers odd?

Emine Alp1,2, Johannes G. van der Hoeven3, Paul E. Verweij1, Johan W. Mouton4 and Andreas Voss1,4,*

1 Radboud University Nijmegen Medical Centre, Department of Clinical Microbiology, Nijmegen, The Netherlands; 2 Faculty of Medicine, Erciyes University, Department of Clinical Microbiology and Infectious Disease, Kayseri, Turkey; 3 Radboud University Nijmegen Medical Centre, Department of Intensive Care, Nijmegen, The Netherlands; 4 Canisius-Wilhelmina Hospital, Department of Medical Microbiology and Infectious Diseases, Nijmegen, The Netherlands


* Correspondence address. Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, PO Box 9015, 6500 GS Nijmegen, The Netherlands. Tel: +31-24-36575-14; Fax: +31-24-36575-16; E-mail: a.voss{at}cwz.nl

Keywords: antibiotic treatment , treatment duration

Sir,

The optimal duration of antibiotic treatment of infections is still controversial. While medical textbooks mainly offer advice for extended treatment duration such as 10 days, 14 days, 4 weeks, 6 weeks or 12 months,15 in clinical practice antibiotic treatment is frequently given for shorter durations (≤7 days). To see whether our hunch was right that ‘even’ numbers of treatment days in this setting are ‘odd’, we prospectively studied the choice, indication and duration of antibiotic treatment of 50 intensive care unit patients, receiving a total of 150 antibiotic courses.

The average number of treatment courses per patient was three, with a range of 1–11; resulting in a total of 1172 treatment days. Amoxicillin/clavulanic acid and ceftazidime were the antibiotics most commonly used. Treatment was given for an uneven number of days to 17 of 18 patients (94.4%) treated with amoxicillin/clavulanic acid and 18 of 25 patients (72%) treated with ceftazidime. Fever of unknown origin (FUO) was the most common reason for starting treatment empirically (Table 1). Of 30 antibiotic courses given for this indication, 21 (70%) were given for an uneven number of days. Overall, 95 (64.0%) of the 149 treatment courses were discontinued after an uneven number of treatment days. When separating short (≤7 days) from long (>7 days) treatment courses, antibiotics were given for an uneven number of days in 89 (92.7%) and 7 (7.3%) of the 110 short and 40 long cases, respectively. By chance, about 28% of the antibiotics should have been stopped during the weekend, but actually less than 10% were stopped on Saturday and Sunday, while 24%, or 1.7 time the expected per day rate, were stopped on Monday.


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Table 1. Indication for antibiotic treatment

 
Duration of antibiotic treatment frequently remains a mystery. While textbooks commonly tell us to treat patients for an even number of days,15 we obviously favour an uneven number of treatment days, especially for short courses. Does this reflect a deep-rooted belief in the sacred numbers 1, 3, 5 and 7, as held by Pythagoras, or do we subconsciously follow an unwritten ‘rule’ that we publicly consider to be superstition namely: ‘The duration of antibiotic treatment is 5 or 7 days or multiples thereof’. Does it reflect common sense that treatment should obviously not be stopped at weekends? Or are we the only ones who believe that even numbers are odd?

References

1. Gwaltney JM, Bisna AL. Pharyngitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia: Churchill Livingstone, 2000; 656–63.

2. Sobel JD, Kaye D. Urinary tract infections. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia: Churchill Livingstone, 2000; 772–805.

3. Bayer AS, Scheld WM. Endocarditis and intravascular infections. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia: Churchill Livingstone, 2000; 857–902.

4. Tunkel AR, Wispelwey B, Scheld WM. Brain abscess. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia: Churchill Livingstone, 2000; 1016–28.

5. Mader JT, Calhoun J. Osteomyelitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia: Churchill Livingstone, 2000; 1182–96.





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