Molecular Characteristics And Infection Preventions Of VanM-carrving Vancomycin-resistant Enterococci

Objectives:In this study,we investigate the clinical features of vanM-carrying vancomycin resistant enterococci(VRE)induced bloodstream infection and the molecular characteristics of 45 vanM-carrying VRE isolated from clinical and environmental samples,and provide the basis for development of vanM-carrying VRE infection control measures.Methods:We summarize the managements of a vanM-carrying VRE induced bloodstream infection patient,and collect the environmental samples according to the Hygienic standard for disinfection in hospitals(2012 edition).Enterococcus feacium is identified by MALDI-TOF MS.Antimicrobial susceptibility are determined by E-test.Pulsed-field gel electrophoresis(PFGE)and multilocus sequence typing(MLST)are performed to analyze the molecular epidemiology of isolates.PCR is used to determine the vancomycin resistance genes and the virulence genes.Conjugation experiments are performed to study the transferability of vancomycin-resistant gene.We compare the molecular characteristics of clinical and environmental vanM-carrying VRE.Additionally,contact isolation and environmental cleaning are performed to prevent the outbreak of vanM-carrying VRE.Results:A 51-year-old man was admitted to our hospital due to recurrent headache and limbs activity disorder.He was diagnosed as cerebral abscess by brain MRI and transferred to intensive care unit(ICU)after stereotactic puncture drainage.The empirical broad-spectrum antibiotics including imipenem-cilastatin(0.5 g,q6h)and vancomycin(1.0 g,ql2h)was immediately initiated.He had a high fever and a blood culture was taken on the 4th day after ICU admission.Three days later,his blood culture yielded vanM-carrying VRE,and the vancomycin was replaced by linezolid according to the susceptibility result.Although a clinical statue had improved,he had a diarrhea with a positive stool culture of vanM-carrying VRE,and treated with montmorillonite powder on the 10th day.Strict contact isolation and microbiological surveillance were performed.Forty-three representative environmental and two clinical vanM-carrying VRE isolates from blood and stool of the patient were classified into 4 PFGE patterns and 2 sequence types(ST78 and ST564),but no VRE was found from environmental surfaces of the neighboring patient of the same ICU.On the 12th day after ICU admission,the patient was transferred to neurosurgery department and showed good recovery and discharged successfully three days later.Conclusions:Although with high resistance and positive for virulence genes,the vanM-carrying VRE induced infection could be effectively controlled by comprehensive managements including microbiological surveillance cultures,strict contact isolation and timely antibiotic treatment.