The Worth of Surveillance for Vancomycin-Resistant Enterococci in the Hematology-Oncology Unit

Background: Vancomycin-resistant enterococcus (VRE) has become a nosocomial pathogen of increasing importance. First identified in Europe in 1988, it has since been identified in multiple sites in the United States and Canada, as well as in Latin America. A 20-fold increase in the percentage of enterococci associated with nosocomial infections that were resistant to vancomycin, from 0.4% in 1989 to 7.9% in 1993, has been reported by the Centers for Disease Control and Prevention. VRE outbreak has been identified on February 2012 in hematology-oncology unit. It has since implemented some outbreak measures in order to control this outbreak, and as part of the control program during this outbreak of VRE infection in oncology-hematology unit of our tertiary care hospital, swab anal cultures have been performed weekly for inpatients as well as at the moment of their hospitalization.

Objectives: To assess the incidence of colonization and infection by VRE of admitted patients in oncology-hematology unit and to evaluate the role of neutropenia and central line as well as their impact on blood stream infection (BSI) by VRE in previous colonized patients.

Methods: All patients admitted to hematology-oncology unit in Instituto do Câncer do Estado de São Paulo São Paulo (ICESP) were undertaken to surveillance for VRE by Hospital Infection Control Committee from March 1, 2012 to May 31, 2014. It is important to highlight that ICESP has not promoted bone marrow transplantation. Neutropenia was defined as a neutrophil count ≤0.5 x 10⁹/L. Feces (in patients with neutropenia) or rectal swab for those with a neutrophil count >0.5 x 10⁹/L were collected for research VRE on admission and weekly for those that persist with negative results. Enterococci were isolated by standard microbiological methods. It was considered patients with colonized VRE when a bacterium is present, without any signs or symptoms of infection. BSI by VRE was defined in patients with positive blood culture for VRE.

Results: A total of 1,666 patients had been screening for VRE colonization. One hundred sixty-one cases of VRE colonization were detected among them. The rate of VRE colonization during hospitalization was 9.7%. The incidence rate of VRE colonization was 9.4 cases per 1,000 inpatient-days. Twenty (12.4%) out of 161 VRE colonized patients developed BSI by VRE. The incidence of BSI by VRE was 1.2 cases per 1,000 inpatient-days. Eleven (55%) patients with BSI by VRE presented Acute Leukemia. A hundred percent of patients with BSI by VRE presented neutropenia and 14 (70%) out of 20 had central venous catheter inserted as well.

Conclusions: We conclude that it is important to perform surveillance for VRE due to our incidence of patients colonized by VRE such as BSI by VRE. We believe these data may justify surveillance attendance and contact precautions. It was observed the importance of neutropenia to BSI by VRE in patients previously colonized. Thus, this fact could suggest that others studies are necessary in order to evaluate the role of antibiotic as linezolid for febrile neutropenia treatment in patients colonized by VRE.