Staphylococcus Aureus α-toxin Effect on Acinetobacter Baumannii Behavior

TUTTOBENE, MARISEL ROMINA; SUBILS, TOMAS; MARTINEZ, JASMINE; TUCHSCHERR, LORENA; RAMÍREZ, MARÍA SOLEDAD

Congreso; World Microbe Forum; 2021

Polymicrobial infections are more challenging to treat and are recognized as responsible for significant morbidity and mortality. It has been demonstrated that multiple Gram-negative organisms take advantage of the effects of Staphylococcus aureus α-toxin on mucosal host defense resulting in proliferation and dissemination of the co-infecting Gram-negative pathogens. Recently, we observed interactions between Acinetobacter baumannii and S. aureus recovered from soft tissues samples from diabetic patient, showing that these two pathogens can be causative agents of diabetic foot ulcer and can coexist in the site. We found that both strains are not affecting each other, either beneficially or detrimentally, showing a state of commensalism between them. In the present work, using three distinct A. baumannii strains, A118 (highly susceptible), A42 (intermediately susceptible) and AB5075 (high resistance) and the Cell-Free Conditional media (CFCM) of diverse S. aureus strains , such as USA300 (MRSA), USA300Δhla, LS1 (MSSA) and LS1ΔagrA, we aimed to further explore S. aureus effect on A. baumannii behavior. Transcriptomic analysis of A. baumannii A118 generated from cells incubated in LB with or without the addition of S. aureus USA300 CFCM was carried out. Phenotypic assays such as motility, hemolytic activity, biofilm, and antibiotic susceptibility were performed. The analysis of the RNA-seq data, using a fold-change cutoff of log2 > 1 (with adjusted P-value < 0.05), showed an extensive effect on expression. A total of 3689 differentially expressed genes associated with a wide variety of functions, such as biofilm formation, virulence, antibiotic susceptibility, among others, were identified. Besides, we observed a decreased of A. baumannii motility with the addition of S. aureus USA300 CFCM or S. aureus LS1 CFCM, and an increased with the addition of S. aureus USA300Δhla CFCM or S. aureus LSIΔagrA CFCM. Hemolytic activity was seen in A. baumannii in the presence of S. aureus LS1 CFCM. Additionally, A. baumannii showed an increased in biofilm formation in the presence of S. aureus USA300 CFCM. An increased in antibiotic resistance to tetracycline in the presence of S. aureus USA300 CFCM was observed.