Peculiarities of the temporal dynamics of biofilm formation of bacteria of the genus Staphylococcus

Justification. Bacteria of the genus Staphylococcus are conditionally pathogenic microorganisms capable of causing purulent-septic diseases. Testing for biofilm (BF) formation can be a useful marker of staphylococcal pathogenicity and have great clinical significance; especially in the chronic course of staphylococcal infections. The aim. To study the kinetics of growth and the dynamics of BF formation by bacterial strains of the genus Staphylococcus. Materials and methods. Ten Staphylococcus strains from the working collection of the Microbiome and Microecology Laboratory of the Scientific Сentre for Family Health and Human Reproduction Problems were used. The measurement of optical density (OD); growth rate; determination of the total microbial number; and assessment of the morphological structure of BFs were carried out for three clinically significant species: Staphylococcus aureus (three strains); S. epidermidis (two strains); and S. haemolyticus (five strains). Sampling was carried out after 2; 4; 8; 10; and 24 h of cultivation. Results. The OD of the starting culture for all tested strains was 0.08 optical units. All tested strains showed comparable growth and a general tendency toward biofilm formation. The stationary phase was achieved after 8 h of cultivation with a total microbial number of more than 8 lg CFU/mL and an OD of 0.216–0.329 units. Cell adhesion to the surface was recorded after 4–6 h of incubation; and after 8 h; the formation of an inhomogeneous BFs was observed. After 10 h; the biofilm structure was reorganized; and after 20 h of incubation; the BFs were completely destroyed; while the total microbial number decreased with a simultaneous increase in OD from 0.288 to 0.562 units due to the transition of the destroyed cells to a suspended state. Conclusion. The features identified in real time expand the understanding of the dynamics of the BF formation of gram-positive bacteria and can be applied in clinical microbiology to prevent recurrent infections caused by staphylococci.