ADHERENCE CHARACTERISTICS OF PATHOGENIC Proteus Mirabilis ISOLATES IN HEP-2 CELLS

Proteus mirabilis is one of the most commonly found Gram-negative opportunistic pathogens in clinical human samples. This microorganism is frequently related to urinary tract infections, facilitated by its ability to degrade urea and express several fimbriae simultaneously. It can also be found in wounds, blood and tracheal secretion. There are several virulence factors that favor this microorganism in infectious processes such as urease, hemolysins, toxins, capsule, siderophore, protease, mobility, biofilm and cell adherence. The mechanisms by which P. mirabilis adheres to epithelial cells in vivo are not completely understood. Some pathogens, such as diarrheogenic Escherichia coli (DEC) pathotypes, the ability to adhere to HEp-2 cells is expressed in specific patterns known as localized adherence (LA), where bacteria adhere to the cell surface as firm agglomerates; aggregative adherence (AA), where the bacteria adhere in a pattern of stacked bricks, forming aggregates of bacteria on the cell surface and in the coverslip; diffuse adherence (AD), where the bacteria adhere diffusely to the cell surface. Among these adherence patterns, the most studied is AA. Some studies have shown that bacteria adhering to this pattern often express intense biofilm, promoting the persistence of infection and making treatment difficult. Adherence to host cells is considered as the main mechanism of pathogenicity of P. mirabilis, and can express a diverse range of fimbriae responsible for adherence to epithelial cells. Therefore, in this work the interaction test with HEp-2 cells with 3h of bacterial-cell interaction was carried out and confirmed with repetitions after 6h of bacterial-cell interaction. The criteria for classification of adherence patterns were the same as those used for DEC. We studied sixty-eight P. mirabilis strains isolated from urine, blood, secretion, tissue and wound samples. All urinary strains showed an AA pattern. In non-urinary strains 85.3% presented AA pattern and 14.7% were non-adherent (NA). Thus, it is possible to conclude that the AA pattern in P. mirabilis is a common feature in urinary strains and strains isolated from blood, secretion, tissues and wounds. This type o adherence pattern is common in bacterial forming biofilm. This biofilm can promote the persistence of infection and making treatment difficult.