[Aerobic bacteria from skin lesions in reptiles and their antimicrobial susceptibility]

Bacterial skin infections are common in reptiles. Although many such infections are influenced by multifactorial problems, specific treatment of bacterial infections is an important consideration. The objective of this study was to evaluate the range of aerobic bacteria in skin lesions of reptiles and to determine their antimicrobial susceptibility.

Swabs of skin lesions from 219 reptiles were cultured for aerobic bacteria between January 2017 and June 2018. Isolates were identified based on growth on selective agar plates, biochemical parameters, as well as MALDI-TOF MS. Antibiotic susceptibility testing was carried out using the microdilution method.

A total of 306 isolates were identified, mostly gram-negative, including Pseudomonas spp. (n = 48), Citrobacter spp. (n = 31, only in chelonians), aerobic spore-forming bacteria (n = 30), Aeromonas spp. (n = 20), Acinetobacter spp. (n = 20), Proteus spp. (n = 15), Staphylococcus spp. (n = 15), Klebsiella spp. (n = 13), Enterococcus spp. (n = 13), Morganella spp. (n = 11) as well as 78 other gram-negative and 12 other gram-positive bacteria. Colonization with 2 (n = 80) or more (n = 16) bacterial isolates was seen in 96 animals. Antibiotic susceptibility testing was carried out with 208 of the 306 isolated bacteria. Many isolates were sensitive (minimal inhibitory concentration [MIC] in µg/ml ≤ breakpoint) to enro- (E) and marbofloxacin (M): 86.4 % MIC ≤ 0.5 (E) and 95.5 % MIC ≤ 1 (M) for Pseudomonas spp., 86.4 % MIC ≤ 0.5 (E) and 90.9 % MIC ≤ 1 (M) for Citrobacter spp., 75.0 % MIC ≤ 0.5 (E) and 100 % MIC ≤ 1 (M) for Aeromonas spp. Trimethoprim/sulfamethoxazol proved to be effective against most of the Citrobacter spp. (90.9 % MIC ≤ 2/38) and Aeromonas spp. (75.0 % MIC ≤ 2/38). Amikacin was effective against nearly all Pseudomonas spp. (97.7 % MIC ≤ 16), Citrobacter spp. (95.5 % MIC ≤ 16) and Aeromonas spp. (93.8 % MIC ≤ 16).

The majority of isolates were gram-negative; the clinical relevance of individual isolates must, however, be evaluated on a case by case basis. Many of the isolated bacteria were sensitive to fluoroquinolones as well as aminoglycosides. Susceptibility testing is recommended since use of these antibiotics should be limited and for every tested group of antibiotics resistant isolates were found.