If you follow zoonotic diseases, you might look at the title of this post and think “What is he rehashing now? We already know Salmonella is common in reptiles, and contact with reptiles is a major risk factor for salmonellosis in people.”
In large part, you’d be right. Not a lot has changed on the Salmonella-in-reptiles front, but since it’s an important issue (and there are still those who haven’t gotten the message), it doesn’t hurt to provide some updates.
A recent study in the journal Biology (Merkevičiene et al. 2022) fits in the “unsurprising but worth a mention” category.
Researchers collected samples from 75 captive reptiles in Lithuania, from private homes and a zoo. All of the reptiles were healthy and none had been treated with antibiotics in the past 6 months. They also collected samples from 22 wild reptiles at three locations in Lithuania. Samples were cultured for Salmonella.
- Overall, Salmonella was isolated from 50 (52%) reptiles; 46 (61%) pets and 4 (18%) wild reptiles.
- 25 different reptile species were tested. One or more positive samples were detected from 68% of species.
- A wide range of different serovars (strains) were detected.
- Antimicrobial resistance was variable, but 24 (48%) of isolates tested were resistant to 1 or more of the antibiotics on the testing panel.
- 10 (20%) isolates were multidrug-resistant (i.e. resistant to 3 or more antimicrobial classes). This includes three wild reptiles that harboured Salmonella resistant to 5 or more of the tested antibiotics (including cefoxitin, tetracycline, chloramphenicol, ampicillin, streptomycin, ciprofloxacin, pradofloxacin, ofloxacin and potentiated sulfonamides). Yikes!
Does this change anything? No, but it highlights (yet again) a few important messages:
- Reptiles commonly harbour Salmonella. These results showed over 61% of pet reptiles were carrying Salmonella based on testing just a single sample. If serial sampling was performed, I suspect the number would be even higher.
- Reptiles should be handled with the assumption they are carrying Salmonella, with careful attention to basic infection control practices such as hand hygiene and preventing cross contamination of objects, surfaces, clothing, etc..
- People at higher risk of serious disease (e.g. very young, elderly, pregnant, immunocompromised) should not have contact with reptiles, and should not live in the same house as a reptile, whether or not they are allowed to have direct contact with them.
- Antimicrobial resistance rates highlight ecological complexities inherent in this silent pandemic of resistance.
I’m not saying to get rid of all captive reptiles. However, it’s important that only lower-risk people are exposed to reptiles and that we do a good job of using basic infection control practices to reduce the risks of transmitting Salmonella to people.