oa Molecular Diagnosis and Vaccines - Molecular characterization of Vancomycin-resistant enterococci isolates from hematology-oncology patients
Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens in many countries with the genotype vanA and vanB being the most important is hospital environment. The objectives of this study is the Molecular characterization of VRE isolated from hematology-oncology patients. Fecal/rectal samples from 50 randomly selected patients together with blood samples from the 11 patients who developed bacteremia. Enterococcal isolates were identified and subjected to antimicrobial susceptibility testing to vancomycin by agar screen method. Vancomycin resistance was confirmed by determining its minimum inhibitory concentration by broth dilution method. Susceptibility of the VRE isolates to different antimicrobials was also determined using the disk diffusion method. Multiplex PCR was used to detect vanA and vanB genes among the isolated VRE strains. Fifty enterococcal strains were isolated from the fecal-rectal samples, of which six (12 %) were VRE (3 E. faecium, 2 E. faecalis and one E. gallinarum). On the other hand, blood cultures from patients with bacteremia were all negative for enterococci. The most significant risk factor for colonization with VRE was previous hospitalization. Other factors included prolonged hospitalization, previous ICU admission, febrile neutropenia, current and previous vancomycin administration. 83.3% of the VRE strains were sensitive to nitrofurontoin, while 83.3% were resistant to ampicillin and erythromycin. vanA gene was detected in two isolates while van B gene was detected in another three isolates. One isolate was found to be devoid of both vanA and vanB. It is concluded that Vancomycin resistance genes are present among the enterococci colonizing the gastrointestinal tract of hematology-oncology patients. This represents a critical risk factor for hospital aquired infection by these pathogens as well as a threat of spread to other pathogens. Surveillance for VRE in high-risk patients together with effective infection control measures and adapted antibiotic policies are important to control transmission of VRE among patients.
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