SPECIES COMPOSITION OF ASSOCIATIONS AND RELATIONSHIPS BETWEEN MICROORGANISMS ISOLATED FROM OSTEOMYELITIS FOCUS

Abstract

Objective. To determine the species composition of the associations isolated from osteomyelitis foci and to study the character of associate relationships based on the biofilm-forming ability data. Methods. The microbiological study included clinical isolates (n=184) obtained from associations (n=88) during primary inoculations from wounds and fistulas of patients (n= 88) with chronic osteomyelitis of long tubular bones. In order to obtain an associative biofilm in vitro, the cultures of competing bacterial strains were daily mixed in 1:1 ratio. The biofilms were grown on the surface of polystyrene plates with subsequent determination of the level of biofilm formation in 24 and 48 hours. Thecoefficient of relationship (CR) was calculated to evaluate the synergistic, neutral and antagonistic relationships between bacteria in the biofilms. Results. The associations of staphylococcus with gram-negative bacteria were most frequently recovered from osteomyelitis foci. On the 1st day of the experiment, 38,6 % of associations had a moderate biofilm-forming ability, and besides, associations of gram-positive + gram-negative bacteria were observed in 36,4%; 42,1% of associations had a low biofilm-forming ability; 19,3% - had a high biofilm-forming ability. After 48 hours the percentage of mild adhesive strains remained at the same level - 38,6%, as for the low adhesive ones it decreased to 36,4%, high adhesive - increased up to 25%. Most bacterial associations manifested antagonistic relationships. Synergism in biofilm-formingby the association of S. aureus + P. aeruginosa was observed in 2 cases,while the level of film-forming was high as on the first and the second day of the study. In several associations it transformed from antagonistic to synergistic or neutral relationships. Conclusion. It has ben established that among the identified associations, the largest specific weight falls on the associations of gram-positive + gram-negative bacteria , while S. aureus is one of the most common components. These associations were noted to have high and mild activity of biofilm -forming on the surface of polystyrene plates. Relationships between the microorganisms isolated from osteomyelitis foci in associations, as a rule, are antagonistic. What this paper adds For the first time, the nature of the relationship between microorganisms in the composition of associations isolated from the osteomyelitis focus has been studied on the basis of biofilm-forming ability data. It has been established that in microbiocenosis of the osteomyelitis foci, the greatest specific weight falls on the associations of S. aureus with gram-negative bacteria. These associations have a high and moderate activity of biofilm formation on the surface of polystyrene plates. The relationships between microorganisms isolated from the osteomyelitis focus as part of associations are usually antagonistic.