Antibiotic prescribing

Editor, – In the article 'Antibiotic prescribing: how can emergence of antibiotic resistance be delayed?' (Aust Prescr 2004;27:39-42) I note the emphasis on using these drugs for the shortest time possible. Is it time to change our advice to patients to 'make sure you complete the course, even if you feel better after a few days'?

The reason for this advice appears to be twofold. Firstly, the infection will recur if incompletely treated. Secondly, the emergence of resistance is facilitated by shorter courses of antibiotics, presumably because relatively resistant strains of the pathogenic bacteria may still be viable at the end of such a course. However, is complete eradication of the pathogen desirable or necessary in the clinical world of bacterial tonsillitis, severe otitis media, bacterial sinusitis, bacterial gastroenteritis, urinary tract infection, impetigo and chest infection? Do we actually have any evidence relating duration of antibiotic courses, emergence of resistant pathogens, and clinical 'cure' in these conditions?

Nancy Sturman
General practitioner
Indooroopilly, Qld

Dr J. Ferguson, the author of the article, comments:

The situation is complex and varies according to the infected site. With infections such as otitis media, when antibiotics are used, the counsel is now to use 'short and sharp' - an adequate dose to eradicate the pneumococcus and short duration to avoid extended selective pressure. Generally, the longer the course, the greater the selective pressure. This is facilitated by the number of bacteria present - an undrained abscess with pseudomonas will see quick emergence of resistance whereas a patient with streptococcal endocarditis will not have resistance emerge despite several weeks of therapy (the bacterial count is much lower and the intrinsic character of the organism less liable to mutational or other resistance acquisition).