Surveillance for vancomycin resistant enterococci in a tertiary institution in south western Nigeria

Abstract

Background: Enterococci are responsible for up to 12% of cases of healthcare associated infections worldwide and cause life threatening infections among critically ill patients. They show intrinsic and acquired resistance to a wide range of antimicrobial agents. Glycopeptide resistance is due to vanA, vanB, vanC, vanD, vanE, vanG and vanL genes.

Objectives: To determine the carriage rate of VRE among patients on prolonged hospitalization in Lagos University Teaching Hospital, assess the antimicrobial resistance pattern of VRE, identify factors associated with VRE colonization and describe the genetic determinants of enterococcal resistance to Vancomycin.

Methods: VRE were isolated from rectal swabs collected from patients hospitalized for seven days or more in Lagos University Teaching Hospital and identified by Matrix Assisted Laser Desorption Ionization (MALDI) and Polymerase Chain Reaction (PCR). Antimicrobial susceptibility testing was performed by E-test. PCR assay for Vancomycin resistance genes was also performed. Data on demographic and risk factors collected by questionnaire was tested for significance using Chi square.

Results: Thirteen of 319 patients surveyed were colonized with VRE; one with vanA E. faecium, two with vanB E. faecium, ten with E. gallinarum and one with E. casseliflavus. Univariate analysis for risk factors associated with VRE colonization was only significant for the ward of admission. Only one VRE isolate showed full resistance to Vancomycin and Teicoplanin. Three were resistant to Ampicillin and nine to Ciprofloxacin but all were susceptible to Linezolid. High-level resistance to Gentamicin was found in four VRE isolates.

Conclusion: There is a low prevalence of VRE in Lagos University Teaching Hospital which may be spreading among patients in affected wards.

Keywords: Enterococcus, Vancomycin, Resistance, VRE