Saturday, July 16, 2011

Nasty MDR Aeromonas from a leech bite. It was only a matter of time.

A 56 yr old man who had leeches applied following facial reconstructive surgery picked up from leeches that were applied an Aeromonas infection that proved to be multi-drug resistant. Ampicillin was used as the initial prophylaxis and later even cipro couldn’t beat the nasty bug back. The flap tissue graft went fully necrotic and failed requiring repeat of the surgery 8 months later.

Given the severity of the outcome for this patient, it is unfortunate that the report, no doubt, continues the insufferable errors regarding the identity of the leech and the diagnosis of the bacterium. The leeches came from a leech supplier. It's already been shown that the leeches universally supplied by commercial outfits are Hirudo verbana, not Hirudo medicinalis. And it's also recently been clear that while the resident crop bacteria in Hirudo medicinalis, is in fact Aeromonas hydrophila, those in in Hirudo verbana most certainly are not; they are Aeromonas veronii.

The implications of these taxonomic identity errors are not trivial. Anyone looking for MDR Aeromonas hydrophila and not finding it in the natural environment could end up scratching their heads – because they’re looking at the wrong bug – the causative agent in this nosocomial leech case was assuredly Aeromonas veronii.

Widespread global use of fluoroquinolones means these antibiotics have been put out there in natural water areas just through flushing. Aeromonas species in leeches are also found living freely in those habitats where they are being exposed to dribbling, but selection-effective quantities of the antibiotics. Since every commercial leech operation needs to replenish its supply of Hirudo verbana from Turkey (as implied in the report), they are all going to bring this nasty bug with them.

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