Bollettino epidemiologico nazionaleThe national AR-ISS antibiotic resistance project: Preliminary data on vancomycin resistance in invasive strains of Enterococcus faecalis e Enterococcus faecium
Delia Boccia, Fortunato D’Ancona, Annalisa Pantosti for the AR-ISS Study Group*
*The AR-ISS Study Group : Stefania Salmaso, Stefania Giannitelli, Susanna Lana, Monica Monaco, and the participating laboratories
In 1999, the European Union Council included antibiotic resistance among the health priorities of the European Community and in 2001 released a resolution entitled “A strategy against the microbial threat”. In this, the first among the interventions deemed necessary to contain the problem was the creation or reinforcement of surveillance system at national or international level that permit the collection of reliable and comparable data and that also provide data on the prescription and use of antibiotics (1).
In response to this recommendation, the national surveillance project known as AR-ISS (Antibiotico-resistenza-Istituto Superiore di Sanità) was developed, the major objective of which was to collect data on antibiotic resistance for several pathogens of clinical and epidemiologic interest which would be nationally representative and comparable with international data. Details on the methods and goals of the study and on the participating laboratories are available at www.simi.iss.it/antibiotico_resistenza.htm
Between June 1, 2001 and January 21, 2002, 459 blood culture isolates of enterococci were notified to AR-ISS, of which 324 (70.6%) were E. faecalis and 120 (26.1%) E. fecium (in the remaining 15 isolates, the strain was not specified).
The median age of the patients from whom enterococci were isolate was 62 years (range 0-92, standard deviation 21.3), and 62.7% were male. A total of 69.3% of the isolates were from hospitals in Northern Italy, and 49% were from hospitals with more than 900 beds. The wards from which enterococci were most frequently isolated were medicine (41.3%), intensive care (12.7%), and surgery (16.7%)
The frequency of vancomycin resistance and overall multi-resistance for the two species are reported in Table 1. A total of 5.9% of the isolates were resistant to 3 or more antibiotics (of different classes) and it is of note that this percent increases to 80.0% if only those isolates that are vancomycin-resistant are taken into consideration.
Table 2 shows the frequency of vancomycin resistance further stratified by various potential risk factors. The frequency of vancomycin-resistant enterococci (VRE) did not vary by age or by sex. Resistance levels were 19.4% in the South, although the 7 resistant strains came from only 2 hospitals (one with 5 cases and the second with two). At present, it is not possible to determine whether these represent clustered cases. VRE was more common in surgical units compared with medical wards and intensive care units (9.8% compared with 6.6% and 6.0%, respectively).
These preliminary data from the first several months of the AR-ISS system have demonstrated that vancomycin resistance is already an important problem in Italy and that levels are higher than in other countries of Europe, where the mean frequency ranger from 0.06% for E. faecalis and 3.8% for E. faecium (5). It appears indeed that Italy along with Greece (where the levels of vancomycin resistance for E. faecium is 23.8%) have the highest levels in Europe (2).
Additional studies are needed to determine the comparability of the Italian data with international data and to evaluate the clinical and economic impact of VRE infections, their possible correlation with the use of glycopeptide antibiotics in Italy, and how many of these infections occur within an epidemic context. It would also be useful to institute quality control for the susceptibility testing, especially to determine if the techniques being routinely used are contributing to an underestimate of the extent of this phenomenon.
Even though the number of specimens reported here does not allow us to draw major conclusions about the possible risks associated with VRE infection, the available data do underline the importance of preventing this infection, especially in the hospital setting. The tools available to control this infection in hospital settings include the prudent use of vancomycin for both prophylactic and therapeutic purposes and implementation of measures designed to prevent person-to-person or environmental contamination. These measures can be achieved through isolation of patients infected or colonized with VRE such that health care workers are not taking care of both colonized and non-colonized patients at the same time, the use of personal protection measures such as the use of gloves and gowns which should be changed after contact with these patients, through careful management and cleaning of gowns, linens, and infected materials, and through scrupulous cleaning and disinfection of surfaces and medical instruments (5).
Bibliography
1. Commissione delle comunità europee. Raccomandazione del Consiglio del 15 Novembre 2001 sull’uso prudente degli agenti antimicrobici nella medicina umana. GU C del 5.2.2002 L34/13.
2. European Antimicrobial Resistance Surveillance System. www.earss.rivm.nl
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6. CDC. Recommendation for preventing the spread of Vancomycin resistance recommendations of the hospital infection control practices advisory committee (HICPAC). MMWR 1995; 44 (RR12): 1-13.