Medical Sciences

Title :

Molecular characterization of clinical isolates of vancomycin and high-level gentamicin resistant Enterococcus faecium and Enterococcus faecalis

Area of research :

Medical Sciences

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Principal Investigator :

Dr. Benu Dhawan, Professor, All India Institute of Medical Sciences (AIIMS), New Delhi

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Executive Summary :

Antibiotic resistance patterns, virulence determinants and molecular characterization of E. faecium and E. faecalis causing Blood stream, skin and soft tissue and urinary tract infections in hospitalized patients. All enterococcal isolates were identified by conventional methods and confirmed by molecular methods and subjected to antibiotic resistance phenotype by disk diffusion. All isolates were screened for the presence of antibiotic resistance genes and virulence genes by polymerase chain reaction. A total of 500 patients with nosocomial E. faecium (73.2%) and E. faecalis (26.8%) infections were enrolled. E. faecium was the predominant blood (82.4% vs. 17.6%) and skin and soft tissue (73.8% vs. 26.2%) culture isolate, whereas in case of urine samples, E. faecium (51.6%) and E. faecalis (48.4%) were isolated in similar proportion. Overall case-fatality rate was 20.4% and infection due to E. faecium was significantly associated with 2.27-fold-higher inhospital mortality rate. In multivariate analysis, independent predictors for mortality due to E. faecium bacteraemia were rapidly fatal status according to McCabe score at the time of admission, endotracheal intubations, gastrointestinal diseases and pulmonary disease/asthma. Resistance rates to ampicillin, ciprofloxacin, rifampicin, erythromycin, teicoplanin and vancomycin in E. faecium isolates were statistically higher than E. faecalis. Vancomycin and teicoplanin resistance was reported in 32.8% of E. faecium isolates, all of which harboured vanA gene. None of the E. faecalis isolates were resistant to vancomycin or teicoplanin. All enterococcal isolates were susceptible to linezolid, tigecycline and fosfomycin. E. faecalis strains harboured significantly more virulence determinants than E. faecium strains. Persistent use of antimicrobial agents in hospitals, in the community and in animal husbandry will certainly further promote the selection and spread of MDR enterococcal clones. Therefore, ongoing surveillance and improved infection control procedures at hospitals are indispensable to curb further spread of these high risk clones.


Dr. Arti Kapil, Professor, All India Institute of Medical Sciences (AIIMS), New Delhi, Dr. Sreenivas Vishnubhatla, Professor, All India Institute of Medical Sciences (AIIMS), New Delhi

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