Staphylococcus aureus biofilm gene analysis: risks for patients with chronic lymphocytic leukemia (CLL)

Biofilms have a complex multicellular structure composed of bacteria and extracellular polymeric substances, which collectively display adhesive properties and allow bacterial cells to stick to each other and to given surfaces. Biofilms may be formed on the abiotic surfaces of medical instruments such as catheters or implants, as well as on biotic surfaces, e.g., living tissues. Biofilm structures are formed in order to increase bacteria’s chances of survival in unfavorable environmental conditions, prevent immune cells from eliminating bacterial cells, and to provide antibiotic resistance. Staphylococcus aureus is one of the most common sources of upper respiratory tract infections and is a procaryote with the ability to form biofilm structures. Biofilm is considered to be, among others, a virulence factorthat contributes to difficulties and therapeutic failures in treating antibiotic-resistant staphylococcal infections. This can pose a huge risk for individuals with an impaired function of the immune system, such as patients with CLL.

A total of 51 S. aureus strains were isolated from 34 patients with CLL treated in the Saint Jan of Dukla Oncology Centre of the Lublin Region (Poland). DNA from bacteria was extracted using the spin-column method and was later used to perform PCR reactions in order to detect the icaA, icaD, icaB, and icaC genes responsible for the formation of biofilm.

An analysis of the electrophoretic separation of amplification products in the studied S. aureus strains showed the presence of icaA genes in 49 (96.08%) isolates, while icaD, icaB, and icaC genes were detected in 45 (88.24%), 47 (92.16%), and 41 (80.4%) S. aureus isolates, respectively.

Our study found a very significant prevalence of all genes responsible for biofilm formation among isolated S. aureus strains, which, in turn, may contribute to chronic staphylococcal infections, difficulties in antibiotic therapies, and may also delay anticancer treatment, undermining its efficiency and even threatening the lives of patients.