Hijacking of host cellular functions in Staphylococcus aureus pathogenesis

  • Bravo-Santano Natalia

Student thesis: Doctoral Thesis


Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of human cells. S. aureus has shown to rapidly overcome traditional antibiotherapy by developing multidrug antibiotic resistance. Furthermore, intracellular S. aureus is protected from the last resort antibiotics – vancomycin, daptomycin and linezolid – since they are unable to achieve intracellular killing. Therefore, there is an urgent need to develop novel anti-infective therapies against S. aureus. Here, I proposed the exploitation of host-directed approaches as a promising strategy. Specifically, I employed three different approaches to unravel those host molecular factors and/or pathways hijacked by MRSA during intracellular infection.By characterizing the host cell metabolism after MRSA infection, I observed several metabolic changes suggesting a starvation-induced autophagic flux and AMPK phosphorylation levels were also increased in MRSA-infected cells. It was hypothesized that intracellular S. aureus induces autophagy for energy generation and nutrient scavenging. Accordingly, host AMPK-inhibition halted S. aureus intracellular proliferation. I further screened 140 host-directed drugs and found three host-directed tyrosine kinase inhibitors – Ibrutinib, Dasatinib and Crizotinib – that substantially impaired intracellular bacterialsurvival. Particularly, Ibrutinib increased host cell viability after S. aureus infection via inhibition of intracellular bacterial invasion or proliferation and we confirmed the importance of the host receptor EPHA2 for staphylococcal infection. Lastly, I performed a genome-wide shRNA screen to test the importance of 16,000 host genes and identified several host genes important for intracellular MRSAinfection. Specifically, I found that silencing the human gene TRAM2 resulted in a significant reduction of intracellular MRSA. TRAM2 is associated with the endoplasmic reticulum SERCA pumps and accordingly, treatment with the SERCA-inhibitor Thapsigargin halted intracellular MRSA proliferation. In summary, I identified three different host-directed drugs – Dorsomorphin, Ibrutinib and Thapsigargin – that impaired intracellular MRSA infection. These findings serve as an important example of feasibility for identifying host-directed therapeutics to tackle S. aureus host cell infection.
Date of Award30 Apr 2019
Original languageEnglish
Awarding Institution
  • University of Roehampton
SupervisorYolanda Calle (Supervisor), Michal Letek (Supervisor) & Volker Behrends (Supervisor)


  • S. aureaus
  • MRSA
  • pathogenesis
  • antimicrobial resistance
  • host-pathogen interactions
  • host-directed therapies

Cite this