Virulence Factors and Antimicrobial Resistance Pattern of Citrobacter freundii Isolated from Healthy Pet Turtles and their Environment

摘要

Background: Zoonotic Citrobacter freundii infection can occur if pet turtle owners fail to hygienically handle the turtle or the turtle?s environment. Therefore, the virulence characteristics and resistance patterns of C. freundii to commonly used antimicrobials should be understood. Methodology: Citrobacter freundii isolates were characterized by conventional pathogenicity tests, such as proteolysis, biofilm formation and hemolysis, PCR assays of virulence genes and antimicrobial disk diffusion tests. Results: Forty seven presumptive C. freundii isolates obtained from 41 fecal and 18 environmental samples including water and soil samples were confirmed as C. freundii by biochemical tests and 16S rRNA gene sequencing. Proteolysis and biofilm formation were shown in 17 and 6 isolates, respectively. No isolates showed hemolysis. The PCR assay for the presence of slt-II or slt-II related genes and via B genes were successful in 2 and 4 isolates, respectively. In the antimicrobial susceptibility test, most isolates were susceptible to all tested antibiotics except ampicillin, amoxicillin, cephalothin, cefoxitin and nalidixic acid. Non-susceptible isolates to penicillins (piperacillin and ticarcillin), fluoroquinolones (ciprofloxacin and norfloxacin), aminoglycosides (gentamicin) and other antibiotics (trimethoprim/sulfamethoxazole) were frequently observed among the isolates. A few isolates were resistant to imipenem, aztreonam, ceftriaxone and cefotaxime. Conclusion: In conclusion, it can be said that pet turtles are a potential public health risk due to the virulence and antimicrobial resistance of C. freundii .