Snake Bite and Bacterial Infection

Most cat and dogs will cause Pasteurella multocida infection. I was curious however these few days because I found that a culture from a patient with snake bites grew Morganella morganii and to my surprise, I am the only one who were actually surprise about this. Google does not. This is because there were a few study (however scarce) regarding snake oral flora and they found out that Snake do have Morganella spp inside their mouth. 

Bacterial infection in snake bite commonly cause by Gram Positive bacteria, mainly Staphylococcus aureus, followed by Coagulase Negative Staphylococci, and Streptococci.

Gram Negative that commonly cause bacterial wound infection in snake bite includes Enterobactericiae; E.coli the most common, Klebsiella Pneumoniae, Morganella morganii and Pseudomonas aeruginosa.

Culture from the snakes fangs, fangs sheaths, venom of various snakes has shown heavy colonisation with many bacteria including: E.coli, Morganella spp, Group D Streptococci, Aeromonas spp, and anaerobes such as Clostridium spp. (Goldstein, 1979). This maybe due to snakes diet which most of his prey defecate when the snake swallow them.

The snake oral flora then can be vary from region to region depending on their diet, species and oral health. 

Retrospective study done In Taiwan for 10 years (2001-2010) has found out that Morganella Morganii was the most common bacteria isolated from Wound infection after snake bite followed by Gram positive Enterococcus species. (Chen CM et al, 2010)

Snake bite interestingly rarely cause bacterial wound infection due to antibacterial properties of the venom itself. A few study has been done and antibacterial properties of the venom was possibly due to the activity of LAAO and PLA(2) enzymes (Perumal SR , 2007)

Thus, antibiotic are not recommended as a prophylaxis for venomous snake bite. Would culture and sensitivity need to be taken before starting antibiotic therapy (White J, UptoDate 2016).

If antibiotic however, need to be prescribed,  it should covered both gram positive and also gram negative particularly the Enterobactericiae family. Augmentin + Ciprofloxacin for minor wound infection and Tasozin for severe wound infection can be used ( Chen CM et al, 2010). 

Salmonella has been also associated with snakes usually acquired by exotic pet owner. Some study found that Salmonella spp can be found in snakes feces thus exposing those who own a snake to salmonella.

So now I know it. Something new to learn everyday.