Staphylococcus Aureus α-toxin Effect On Acinetobacter Baumannii?S Behavior

FERNANDEZ, JENNIFER S.; DANG, EMILY; TUTTOBENE, MARISEL ROMINA; CHANG, STEVE; MARTINEZ, JASMINE; NAKANOUCHI, JUN; CANTERA, VIRGINIA; IRIARTE, ANDRES; TUCHSCHERR, LORENA; RAMÍREZ, MARÍA SOLEDAD

Congreso; ASM Microbe 2020 American Society for Microbiology; 2020

Polymicrobial infections are 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 ofStaphylococcus 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. aureusrecovered from soft tissues samples from a 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, eitherbeneficially 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) anthe 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 antibioticsusceptibility 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 offunctions, such as biofilm formation, virulence, antibiotic susceptibility, among others, were identified. Moreover, we observed decreased motility of A. baumannii with the addition of S. aureus USA300 CFCM or S. aureus LS1 CFCM,and an increase 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 inbiofilm formation in the presence of S. aureus USA300 CFCM. An increase in antibiotic resistance to tetracycline in the presence of S. aureus USA300 CFCM was observed.The present results showed that A. baumannii can respond to soluble molecules secreted S. aureus and agreed with other studies showing strain specific effects and responses. This versatility of A. baumannii to sense and respond toaureus molecules adds evidence of the ability to adapt to different conditions.