Erythromycin for prokinesis: imprudent prescribing?

There are increasing problems with antimicrobial resistant bacteria in intensive care. Some examples include Clostridium difficile, methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum beta-lactamase producing Gram-negative bacilli and Acinetobacter baumanii. There is overwhelming evidence that the use of antibiotics is a driving factor for the emergence of resistance [1]. This problem is particularly severe in intensive care areas where antibiotic use is high. Does the current practice of prescribing of erythromycin for prokinesis constitute prudent use of antimicrobials [2]?The mechanisms by which antibiotic use can increase antibiotic resistance have been reviewed by Lipsitch and Samore [3] and include: selecting in favour of resistant strains; creating colonization opportunities for resistant strains (assuming competition between resistant and susceptible strains); and encouraging an increased colonisation 'load'. In addition, antibiotic use can more rarely select in favour of the emergence of de novo resistance.The predominant MRSA strains in the UK are resistant to erythromycin. We recently conducted an observational carriage study that supported the view that MRSA and methicillin-susceptible S. aureus strains compete for colonisation space in the anterior nares [4]. Thus, exposure to macrolides has the potential to alter the composition of the resident bacterial microbiota in the anterior nares, leading to selection of MRSA. In support of this, treatment with slow release clarithromycin has been shown to eliminate nasal carriage of S. aureus [5]. This would leave patients more susceptible to colonisation and infection with MRSA.Berg and co-workers [5] also showed that treatment with a macrolide increased macrolide resistance in the oropharyngeal flora. This effect was still present at an eight weeks follow up.Erythromycin as a prokinetic agent is used at sub-therapeutic doses, which particularly promotes selection of mutational resistance [1,