FUNCTIONAL PARAMETERS OF NEUTROPHILS RELATED TO INITIAL STEPS OF NEUTROPHIL-PROVIDENCIA SPP. RECOGNITION

CASTRO, J; BIRNBERG-WEISS F; PITTALUGA VILLARREAL JR; SERAFINO A; GOMEZ S.A.; LANDONI V.I; FERNÁNDEZ G.C

San Luis

Congreso; LXXI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2023

Antimicrobial resistance is a significant problem for the treatment of infectious diseases worldwide. Providencia spp. are Gram-negative bacteria that belong to the Enterobacteriaceae family. Infections caused by species of Providencia stuartii (Ps) and Providencia rettgeri (Pr) are mainly of the urinary tract, followed by pneumonia, meningitis, endocarditis, wound infections and septicemias. In recent years, the relevance of Providencia spp. infections is growing since they have intrinsic antimicrobial resistance, which makes treatment of these multidrug-resistant (MDR) strains challenging. The innate immune response against these pathogens has not been previously studied. In our first study we reported some striking differences in human neutrophils (PMN) responses against Providencia spp. compared to E. coli ATCC (Eco, positive control). In this sense, we observed that Pr poorly induces the respiratory burst in PMN compared to Ps and Eco. Additionally none of the strains, Ps or Pr, were able to induce Neutrophil extracellular traps (NETs) compared to Eco. In concordance with these results, we found that bacterial killing by PMN resulted less effective for Pr.In this work, our aim was to deepen the study of the interaction between human PMN and multi-resistant strains of Ps and Pr, focusing on early events of PMN activation upon bacterial challenge. For this purpose, we exposed isolated human PMN (n=6) to a clinical isolate of Ps and Pr and used Eco as a positive control in a PMN:bacteria 1:10 ratio. First, we evaluated PMN chemotaxis for 30 min towards bacteria using a Boyden chamber, and found that all strains were chemotactic for PMN compared to basal (p