I’ve been digging around in the scientific literature all about appendicitis and I’ve ended up here. Long gone are the days when medicine foolishly considered the appendix without purpose – a dispensable ‘extra’ of the GIT and now, thanks to genetic PCR bacterial identification, gone also is its more recent portrayal as something sinister – a potential harbourer of ‘bad bugs’. The current consensus about this apparently complex little sac is that it constitutes a ‘safe house’ for the microbiota within the GIT, making one of its key roles the healthy recolonisation of the gut following diarrhoeal episodes and even oral antibiotics. Amazingly, antibiotics that can quickly sterilise the rest of the digestive tract, fail to clean out the appendix, due in part to its specialised and exaggerated biofilm as well as its more diverse and environmentally tough species. Wouldn’t you know it, the strange little sac has a critical role in keeping us well?!
Given this radical rethink of the healthy appendix I wondered whether medicine’s understanding of appendicitis and in particular what causes it, had also undergone a revolution. This condition, which was first described over 100 years ago has confounded scientists and clinicians ever since – I love this quote from a 1972 paper in the Medical Journal of Australia (Williams):
“It is interesting and humiliating that a small organ which in man performs no useful function can so frequently give rise to problems which, if not treated, may have fatal complications, and of which we
still do not fully know the cause.”
There’s been the fibre theory, hygiene hypothesis, obstruction theory and infection, with worms, viruses and bacteria all being implicated at times (the latter include both commensals turned nasty and outright pathogens), all with equivocal evidence, but at last we seem to be making some headway! The progress again seems to pivot on the findings of newly available PCR testing, as previous culture based mapping of the microbiome specific to the inflamed appendix found nothing of real note. PCR testing of sick appendices have now revealed diverse microbiota but most strikingly, the presence and large proportion of Fusobacterium.
Who are these Fusobacterium guys and where do they come from?
Yup. You guessed it. Your gob! These gram negative anaerobic oral commensals, which are one of the most abundant species in both healthy and diseased gobs are getting themselves a bad name all around town. Implicated in far-reaching things from adverse pregnancy outcomes to cardiovascular disease. the growing evidence for their role in both appendicitis and colorectal cancer, and perhaps (?) a connection between the two, is quite striking. Trick is…nobody knows how the Fusobacterium travel beyond the oral cavity and under what conditions. Cue…creepy sci-fi soundtrack.
At this stage no one is saying this is the only cause of appendicitis and certainly other species have been implicated. Much more research is needed but there is likely to be a lot more published following on from this important discovery. One of the key puzzles for scientists has been why appendicitis incidence is on the rise again in developed countries in spite of better hygiene, following an initial decline between the 70s-80s. Also, if Fusobacterium are one of key the culprits, why are boys, typically aged 10-19yrs, more likely to be the victims? There’s still so much to piece together but at least for now it’s useful to view the much maligned appendix in a new light.
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