Infection of Diabetes Foot Caused by Carbapenem-Resistant Proteus penneri Mediated by a Novel Plasmid Containing bla(NDM)

OBJECTIVE: A strain of Proteus penneri with carbapenem resistance was found in a patient with a diabetic foot infection. We studied drug resistance, genome, and homology of P. penneri to support clinical prevention and treatment of infection caused by carbapenem-resistant P. penneri (CR-PPE). METHODS: The strains were obtained through bacterial culture from purulence. VITEK 2 compact (GN13) and Kirby–Bauer (K-B) disk diffusion methods were used for antimicrobial susceptibility testing. Ceftriaxone, amikacin, gentamicin, ampicillin, aztreonam, ceftazidime, ciprofloxacin, levofloxacin, cefepime, trimethoprim-sulfamethoxazole, tobramycin, cefotetan, piperacillin-tazobactam, ampicillin-sulbactam, ertapenem, piperacillin, meropenem, cefuroxime, cefazolin, cefoperazone/sulbactam, cefoxitin, and imipenem were used for antimicrobial susceptibility testing. After bacterial genome extraction, sequencing, and sequence assembly, whole-genome sequencing (WGS) was performed to explore the CR-PPE genotype. RESULTS: CR-PPE was resistant to two carbapenems (imipenem and ertapenem), ceftriaxone, and cefazolin, and was sensitive to aztreonam, piperacillin-tazobactam, and cefotetan. WGS results depict that the resistant phenotype of CR-PPE is consistent with the genotype, without common virulence genes of Enterobacteriaceae bacteria detected (virulence factor database). The carbapenem resistance gene bla(NMD-1) is contained in a new plasmid, pWF127-NDM. The transposon Tn125 in pWF127-NDM carrying bla(NMD-1) has almost the same structure as Tn125 in the reference plasmid pHFK418-NDM (Accession: MH491967). In addition, through phylogenetic analysis, CR-PPE depicts the closest evolutionary relationship with GCF 024129515.1, which was found in Gallus gallus in the Czech Republic in 2019 (downloaded from National Center for Biotechnology Information database). According to the evolutionary tree, CR-PPE has high homology with the two P. penneri strains found in China. CONCLUSION: CR-PPE exhibits strong drug resistance owing to the presence of multiple resistance genes. CR-PPE infection should receive more attention, especially in patients with underlying diseases, such as diabetes and weak immunity.