Bloodstream infections and herpesvirus activation following intensive chemother­apy of adult oncohematological patients

Abstract

Intensive cytostatic chemotherapy is a standard strategy for leukemia treatment. Meanwhile, such treatment causes negative effects, i.e., including lymphopenia, granulocytopenia and damage to tissue barriers associated with significant risks of infectious complications, especially, bacterial sepsis and viremia. Our study was aimed for identification of bacteremia and fungemia in oncohematological patients following intensive chemotherapy, and assessment of potential modifying role of herpesvirus infections. We assessed frequency of infectious complications and their etiological agents in two groups of oncohematological patients treated at the Russian Institute of Hematology and Transfusion, especially focusing on mixed infections. Throat smears, venous blood, as well as urine and sputum specimens were taken for routine bacteriological cultures. Whole blood leukocytes were virologically tested by PCR, using standard examination protocol. Our first virological study was performed for respiratory infections and included 85 randomly chosen patients. Influenza and parainfluenza viruses, respiratory syncytial virus, rhinovirus, adenovirus were detected in blood of single patients. Meanwhile, herpesviruses were detectable in 42% proportion of cases, i.e., HSV, EBV, and CMV DNA in blood cells were revealed in 5.2%, 26.3%, and 10.5%, respectively. Viral infections were not associated with positive bacteriological findings in this group. Our group of 33 clinical cases with proven sepsis observed among 64 patients. Generally, Gram-positive species prevailed over Gram-negative bacteria (69.2% versus 30.8%). However, the ratio of detectable Gram-negative flora was found to be increased from 23.1% to 40.2% between 2002 and 2013 (p<0.05). Coagulase-negative staphylococci (CoNS) prevailed among Gram-positive microorganisms, in particular, S. epidermidis and S. aureus), whereas Enterobacteriaceae, especially, E.coli, dominated among the Gram-negative bacteria. Interestingly, 4 of 11 patients with coagulase-negative bacteremia had a concomitant herpesvirus infection: 2 cases were associated with EBV; 1, with CMV, and 1, with HHV6/EBV coinfection. Therefore, a high ratio of viral and bacterial co-infections may be revealed in a number of patients with proven sepsis. Moreover, common reactivation of herpesviruses may cause immunosuppression, or represent additional immunodeficiency markers predictive for bacterial infections at later terms. Therefore, one should take into account their predisposal for severe infectious complications when planning he­matopoietic stem cell transplantation (HSCT) for these patients.