INTRODUCTION: Febrile neutropenia (FN) is the evolution of fever in a patient 
with neutropenia over 38.0°C. Neutropenia is diagnosed when absolute neutrophil 
count (ANC) <1500 cells/µL. FN represents a common complication of cancer 
treatment. Hence, it is featured to be a major cause of morbidity and mortality 
in cancer patients. Staphylococcus aureus is one of the most important 
microorganisms isolated from the blood of febrile neutropenic patients. 
Infections caused by S. aureus range from mild to life-threatening diseases. 
Biofilm production by S. aureus is one of the most significant virulence factors 
of the bacterium as it prevents the penetration of antibiotics. Recently, it has 
been shown that S. aureus carries the ica operon responsible for biofilm 
production. The aim of the work is to determine a genotypic characterization 
that includes not only the detection of icaA and icaD genes in S. aureus but 
also the determination of their relation to clinical and microbiological 
features. Empiric antibacterial treatment was recommended for cancer patients 
receiving chemotherapy.
MATERIALS AND METHODS: The relation between the presence of icaA and icaD and 
biofilm production was determined in a collection of 66 S. aureus samples from 
febrile neutropenic patients. Biofilm-forming ability was tested on Congo Red 
agar plates. Also, the effect of the most sensitive antibiotics on the bacterial 
cells was determined by an electron microscope.
RESULTS: Of the bacterial samples, 48 were biofilm-productive and 18 were 
non-biofilm productive. For the biofilm productive bacteria, 37.5% were positive 
for icaA, 22.9% were positive for icaD and 10.4% were positive for both. 
Linezolid was the most effective antibiotic and it is highly recommended for the 
treatment of febrile neutropenia caused by biofilm-productive S. aureus. Severe 
changes were found on the bacterial cell after being treated with Linezolid. The 
icaA and icaD genes were present in only 50% of biofilm-productive bacteria.
CONCLUSION: The ica operon is present in only 50% of biofilm-productive S. 
aureus and Linezolid is the best antibiotic against these bacteria.