1. REDUCED RATES OF VANCOMYCIN RESISTANT ENTEROCOCCI (VRE) COLONIZATION
AFTER IMPLEMENTATION OF INFECTION CONTROL MEASURES
L. Galani, V. Sakka, S. Tsiodras, M. Pantelaki, I. Galani, M. Souli, A. Antoniadou, S. Athanasia, FV. Kontopidou,
H. Nikolaou, H. Fytrou, N. Siafakas, L. Zerva, H. Giamarellou
University General Hospital ATTIKON, Athens, Greece
P1697
Objective: The aim of the study was to evaluate the effect of infection control measures that were applied during one year period after an outbreak of VRE colonization in our hospital.
Methods: A hospital wide prevalence study was performed during the 20 April-30 May 2005 period, recording fecal carriage and clinical VRE isolation. Presence of vancomycin resistance genes and species identification was assessed by multiplex PCR and clonality of isolates by PFGE. A case-control design, using two randomly selected VRE (-) controls for each positive case, was performed to identify cases with VRE colonization and to evaluate risk factors for such colonization. Control measures including patient cohorting, education efforts about hand hygiene and control of vancomycin use were instituted. An active surveillance problem was established for high risk patients identified through the case control study. A new survey was conducted in October 2006 in order to evaluate all control efforts.
Results: During the initial outbreak of colonization 460 samples were evaluated from 367 patients. Total mean VRE carriage was initially 19.7%. All isolates were identified as E. faecium, with vanA genotype. Multivariate analysis identified immunodeficiency (OR: % CI: ), any invasive device (OR: 5.5, 95% CI: ), and duration of antimicrobial treatment prior to VRE isolation (OR: 1.2, 95% CI: ) as the most important predictors for VRE positivity. During the 2nd screening 132 patients were screened and 11 were found to be positive for VRE colonization (8.3%, p=0.01). From these 4 (3%) were hospitalized in the orthopedics department, 4 (3%) in the hematology unit and the other 3 in internal medicine wards. VRE colonization was detected only in patients at high risk who had been already put in cohort for other multidrug resistanse pathogens.
Conclusions: The implementation of infection control measures and an active surveillance screening program targeting high risk patients resulted in a significant decrease of VRE isolation rates. High rates of VRE colonization can be controlled by timely and intensively applied infection control and antibiotic use measures, preventing the emergence of clinical infections.
ABSTRACT
Results (1)
Results (2)
Despite the fact that enterococci have been considered to have relatively low virulence, in the past few years these organisms have emerged as significant pathogens for urinary tract, surgical wound and bloodstream infections. Clinical infections are mainly caused by two species: Enterococcus faecalis 85-90% and Enterococcus faecium 5-10%.
Enterococci with acquired, plasmid-mediated, high-level resistance to glycopeptide antimicrobials have been increasingly implicated in nosocomial outbreaks of colonization and infections due to these pathogens and may result in high morbidity and mortality. Most vancomycin resistant enterococci (VRE) are E. faecium strains and it has been observed a favourable increase in the proportion of this strain. Clinically evident VRE infection is only the tip of an iceberg; times more patients are colonized than are infected.
In December 2003, 28.5% of the ICU enterococcal isolates reported to the National Nosocomial Infections Surveillance (NNIS) system in the United States were resistant to vancomycin. Published rates of colonization with VRE among hospitalized patients vary widely between studies 2% to 32%. Prevalence of VRE among nonhospitalized patients has been reported between 1% and 3.5%; usually belonged to nonepidemic isolates.
Introduction
MULTIVARIATE ANALYSIS
3 Surveys with 10-days interval: (20 April-30 May)
460 samples evaluated from 367 patients
MULTIPLEX PCR: 69 isolates with high resistance
to vancomycin (MIC>256) from 58 patients were analyzed:
* OR expressed per additional hospital day.
** in models adjusting for age, gender, an immunodeficiency state, duration of hospital stay prior to the positive culture result, presence of a hematological malignancy or an invasive device
E. faecium (1091bp)
VanC (815/827bp)
E. faecalis (475bp)
VanA (732bp)
Μ Μ
VanB (647bp)
Initial Screening
April – May 2005
All Strains identified as E.Faecium and all carried the vanA gene
A routine nosocomial infections survey done in February 2005 revealed 4 patients with VRE colonization (feces and sputum) and one with VRE bacteremia, all oncology-hematology patients.
A retrospective survey (April2005) revealed a cluster of VRE isolation in clinical specimens, from patients in different wards. A rectal swab specimen was collected from every hospitalized patient, in three subsequent surveys with 10-days intervals from April 20th to May 30th (Initial screening)
Control measures including a multidisciplinary team, patient cohorting, environmental cultures, fecal and hand cultures from all hospital personnel and from all renal hemodialysis patients, education efforts about hand hygiene and control of vancomycin use were performed.
Presence of vancomycin resistance genes and species identification were assessed by multiplex PCR.
Clonal relationship was assessed with pulse-field-gel-electrophoresis (PFGE).
For each patient colonized with VRE, two patients with no VRE isolated in their surveillance cultures were randomly selected as controls. Demographics, comorbitidies, use of invasive devices and antimicrobial exposure were recorded.
An active surveillance program for early detection for VRE-colonized patients was established for high risk patients identified through the case control study.
A new survey was conducted in October 2006 in order to evaluate all control efforts.
(Final screening)
Materials & Methods
Reduced Rates one year after the implementation of control measures
P = 0.01
Figure 1: Pulsed-field gel electrophoresis patterns of VRE isolates after digestion of genomic DNA with SmaI
clone
C A C C C C A A B B B D
Conlusions
Final Screening
October 2006
The implementation of infection control measures and an active surveillance screening program targeting high risk patients resulted in a significant decrease of VRE isolation rates.
High rates of VRE colonization can be controlled by timely and intensively applied infection control and antibiotic use measures, preventing the emergence of clinical infections.
8 unique restrictional profiles were identified. Two frequently presented clonal types (A and B) with 29 and 25 strains respectively were identified among these profiles.
PFGE