Pathology and prevalence of antibiotic-resistant bacteria: a study of 398 pet reptiles

14 December 2022

November saw the veterinary sector join forces with the NHS to pilot an antibiotic amnesty in response to the ever-growing concern of antibiotic resistance in humans and domestic animals. Through adopting a One Health approach, the fields of human and animal medicine came together to support the welfare of people, pets and the planet and to champion the judicious use of antimicrobials. This quarter’s Featured Article reminds us that not only cats and dogs require prudent use of antibiotics, as the authors studying antibiotic resistance in 398 pet reptiles found.

The authors of the paper note that the study emerged from the necessity for more information on the subject, especially as numerous bacterial agents found in pet reptiles have zoonotic reverberance. The Romanian study focused on the analysis of pathologies responsible for diseases in pets kept in terrariums, aiming to better understand the features of antibiotic therapy, bacterial load and antibiotic resistance in the species. Taking place over a period of three years, the 398 cases were presented for consultation and treatment in a specialized reptile clinic.

Bacterial strains were isolated, processed in a Bacterial Diseases diagnostic laboratory, cultured and bacterial strains identified. An antibiogram was then performed on the isolated strains using VITEK®2 automated equipment. Gram-negative strains were tested against sixteen antimicrobials, whilst Gram-positive strains were tested against nineteen antimicrobials.  Isolates were then categorized as susceptible, intermediate or resistant. Isolates resistant to three or more classes of antimicrobials were classified as multi-drug resistant.

Commonly isolated bacterial strains included Enterococcus faecalis, Pseudomonas aeruginosa, Stenotrophomonas (Xanthomonas) maltophilia, E. coli, Klebsiella oxytoca spp., Beta-hemolytic streptococci, Staphylococcus aureus, Citrobacter spp., and Proteus spp. The bacteria exhibited diverse degrees of resistance against most of the antimicrobials, including cephalosporins (cefalexin, cefuroxime, and cefquinome), macrolides (erythromycin), lincosamides, penicillins, (ampicillin, amoxicillin/clavulanic acid, and amikacin), florfenicol, tetracyclines (tetracycline and doxycycline), and aminoglycosides (gentamycin). Resistance was less commonly reported for chloramphenicol, sulfonamides, and quinolones.

The authors stress that the importance of this study stems from the isolated bacteria representing important zoonotic risks to reptile owners, whereby pets become potential reservoirs for infection. Long-term antimicrobial treatments have undoubtedly influenced the evolution of resistant strains, with the majority of bacteria in this study exhibiting resistance against the majority of commonly used antibiotic combinations, including penicillins, cephalosporins, macrolides and tetracyclines. The study agreed to a large extent with other literature investigating the emergence of antimicrobial resistance in reptiles.

Published in Animals (, this study further highlights the importance of careful antibiotic therapy in all pet species, domestic and exotic, to counteract the evolution of resistance. Continued studies of this kind can evidence and monitor the situation as the efforts of veterinary professionals continue.