Detection of Carbapenem Resistance of Proteus mirabilis Strains Isolated from Foxes, Raccoons and Minks in China

SIMPLE SUMMARY: Proteus is found abundantly in soil and water, and it has been known to cause human urinary tract infections and food poisoning. Currently, the opportunistic pathogen Proteus mirabilis (P. mirabilis) is also found to be an emerging threat to animals, such as birds, fish, dogs, etc. In this study, we examined the antibiotic resistance genes and virulence genes of P. mirabilis isolates from raccoons, foxes and minks. Among a total of 53 P. mirabilis isolates, the proportion of bacteria resistant to three or more antibiotic classes was up to 73.58%, and the detection rate of carbapenem-resistant P. mirabilis isolates was up to 71.7%, putting human health at risk. The close evolutionary relationship between P. mirabilis isolates from animals and the farm environment suggested that multidrug-resistant P. mirabilis from animals could pose a great environmental threat. In addition, the carriage rate of virulence-associated genes was not positively correlated with P. mirabilis pathogenicity in a Galleria mellonella model, highlighting the importance of further understanding the virulence of P. mirabilis in future studies. ABSTRACT: Proteus mirabilis, an opportunistic pathogen, is found to be an emerging threat to both animals and humans for a variety of infections. However, the characteristics of P. mirabilis infections from foxes, raccoons and minks remain unclear. In this context, we identified the antibiotic resistance genes and virulence genes of P. mirabilis isolates from foxes, raccoons and minks in China. Most isolates showed resistance to florfenicol (90.57%), trimethoprim-sulfamethoxazole (73.58%), and imipenem (71.70%). A total of 73.58% of isolates were resistant to antibiotics from at least three or more classes, and were categorized as multi-drug resistant. A total of 33.33% of the isolates were resistant to antibiotics from seven classes. The most prevalent resistant were sul1 (94.34%), followed by floR, bla(TEM), aac(6′)Ib-cr and bla(OXA-1) with the detection rate of 88.68%, 83.02%, 71.70% and 60.38%, respectively. Among the 51 P. mirabilis isolates that were resistant to beta-lactam antibiotics, all isolates carried at least one beta-lactam gene. In addition, bla(NDM) and bla(OXA-24) genes were firstly reported in carbapenem-resistant P. mirabilis isolates from foxes, raccoons and minks. All isolates exhibited the virulence genes ureC, zapA, pmfA, atfA and mrpA. P. mirabilis isolates carrying all detected 10 virulence genes from different animal species showed different lethal abilities in a G. mellonella larvae model. More importantly, the profiles of antibiotic resistance genes of isolates from fur animals and the environment were generally similar, and phylogenetic analysis showed that the P. mirabilis isolates from farm environment samples may have close relatedness with that from animals.