AUSTRALIAN LIFE SCIENTIST (Australia) 20 August 07 Fangs for the memory: It’s not just venom or toxins that cause harm when an angry critter bites – many species have a habit of leaving behind nasty bacterial infections as well. (Graeme O'Neill)

It was once mandatory in Western movies for villains and the odd innocent cowpuncher to die after being punctured by a rattlesnake.

A bite from a big rattler, especially the eastern diamondback Crotalus adamanteus, which grows to 2.75 metres, was a fast ticket to Boot Hill in the days before anti-venom.

Compared to some Australian snakes, rattlesnake venom is not particularly toxic; predominantly it contains hemotoxins rather than paralysing neurotoxins. Nevertheless, rattlers rank among the world's most dangerous snakes because of the huge amounts of venom they can inject with their formidably long fangs.

Californian microbiologist Diane Citron and her colleague Dr Ellie Goldstein, an infectious diseases specialist at the University of California in Los Angeles, have studied the bacteriology of bite wounds - among other projects - at Citron's base, the R.M. Alden Research Laboratory in Santa Monica, for many years.

They have found that, in addition to the hemotoxins present in rattler venom, a bite can also deliver an impressive list of aerobic and anaerobic bacteria.

In subsequent studies they also found that rattler venom also contains a number of potent bactericidal compounds capable of rapidly killing antibiotic-resistant strains of species like Staphylococcus aureus, so anyone surviving a rattler bit might be lucky enough to avoid a nasty bacterial infection.

Several years ago Goldstein, who regularly co-authors research papers with Citron, rang her collaborator with an unusual offer.

A young man who had visited the emergency clinic several times for treatment for bites from his pet snake had finally concluded that life in close proximity to an ill-tempered rattlesnake was an unnecessary hazard. Smartly, he donated the reptile to Goldstein and to science.

Previous experience with snakebites had revealed an absence of infection, and Citron was intrigued by the opportunity to examine the late serpent's mouthparts for bacteria.

Citron and Goldstein carefully dissected the rattler's mouth, and aspirated or swabbed all parts, then cultured the samples on a variety of agar media. Curiously, the colonies that grew on their agar plates proved to be typical of the anaerobic gut flora of mammals, including Fusobacterium, Clostridium, Bacteroides, Salmonella, Enterobacter, Serratia, Klebsiella and the inevitable E. coli.

What on Earth were microbes from the distal end of a mammalian gut doing at the proximal end of a reptile?

The penny dropped. The snake ingests its mammalian prey head first, compressing its abdomen, thus ejecting a sample of the prey's enteric flora into the snake's mouth to be passed on to the next victim. Fangs for the memory...
It’s not just venom or toxins that cause harm

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• AUS Press: It’s not just venom or toxins - W von Papineäu, Tue Aug 28 12:12:17 2007