Biofilm formation by blood stream staphylococcal isolates from febrile neutropenic cancer patients

Abstract

Objectives: The aim of this study was to define the main causative organisms of bacteremia in febrile neutropenic patients and to study the prevalence of biofilm forming capability of staphylococci in blood isolates of these patients. Background: Blood stream infections remain the main cause of morbidity and death in patients undergoing treatment for cancer. Researchers showed that the first step of staphylococcal infection is the attachment to surfaces of various materials and biofilm formation. Biofilms render the cells less accessible to the defense system of the host, thus impairing the action of antibiotics. Therefore, methods identifying strains with a capacity for biofilm formation are necessary to develop effective strategies for biofilm control and improve patient care. Patients and methods: The study included 185 participants divided into two groups; group I included 155 cancer patients and group II included 30 healthy participants as control. The participants were subjected to the following: medical history, blood cultures, antimicrobial susceptibilities of the staphylococcal isolates, Congo red agar (CRA) test, and microtiter plate (MTP) test. Results: Positive blood culture represented 33% of cases; of them, gram-positive bacteria represented 78.5% (40 cases staphylococci): 17 cases were of Staphylococcus aureus and 23 cases were of Staphylococcus epidermidis . Biofilm-positive strains of S. aureus were 4/17 (23.6%) when assessed with CRA and 6/17 (35.3%) when assessed with MTP. Biofilm-positive strains of S. epidermidis were 7/23 (30.4%) when assessed with CRA and 10/23 (43.5%) when assessed with MTP. Most strains that form biofilm were more resistant to most antibiotics compared with other strains. Conclusion: There is an association between biofilm production with persistent infection and antibiotic therapy failure. The MTP is the test of choice in detecting biofilm formation among staphylococci.