Polymicrobial infections involving fungal and bacterial pathogens are increasingly common among hospitalized patients. However, there is a paucity of research focused on studying polymicrobial infections. The fungal pathogen Candida albicans is the most common cause of invasive fungal infection and the third most common cause of nosocomial bloodstream infections in the US. Invasive fungal infections with C. albicans have devastatingly high mortality rates compared with bacterial infections. Bloodstream fungal infections, which are mostly monomicrobial, result in a 40% mortality rate. In contrast, intra-abdominal fungal infections (IAI), which are often polymicrobial involving both fungal and bacterial species, result in a 50-75% mortality rate, which far exceeds bacterial mono- or polymicrobial IAI mortality rates (20%). Fungal involvement also leads to increased rates of relapse and more severe disease scores. The mechanisms associated with this exacerbated mortality are currently unknown. The objective of this application is to characterize the host and microbial mechanism/s contributing to synergistic lethality during polymicrobial fungal-bacterial intra-abdominal infections (IAI). Our central hypothesis is that polymicrobial Candida-bacterial intra-abdominal infections promote synergistic effects on mortality by inducing a pathological inflammatory response locally and systemically (sepsis). Mechanistically, the response is induced by both microbe-microbe interactions and cross-kingdom stimulation of innate immune receptors. The first specific aim of this project is to test the hypothesis that specific eicosanoi signaling pathways (COX-1; PGE2; EP3) are required for pathological inflammation and lethality observed during polymicrobial fungal-bacterial IAI. The second specific aim is to test the hypothesis that PRR signaling from both fungal and bacterial pathogens is required for enhanced eicosanoid production, inflammation, and lethality observed during polymicrobial IAI. The third specific aim is to test the hypothesis that C. albicans promotion of bacterial toxin production augments inflammation and mortality during fungal-bacterial polymicrobial IAI.

Public Health Relevance

This application seeks to characterize novel host and microbial mechanisms promoting synergistic mortality observed during lethal polymicrobial IAI with Candida albicans and Staphylococcus aureus using a well-developed murine model of polymicrobial IAI. A goal of this work is to challenge current clinical paradigms related to this devastating disease and identify potential points during the host response that can be targeted pharmacologically following infection that would provide new information that could be used clinically to reduce mortality in IAI patients. These studies also have the potential for broad impact, as Candida albicans also exerts synergistic mortality during intraperitoneal infections with other enteric pathogens.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Duncan, Rory A
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Louisiana State Univ Hsc New Orleans
Schools of Dentistry/Oral Hygn
New Orleans
United States
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Ikeh, Mélanie A C; Fidel Jr, Paul L; Noverr, Mairi C (2018) Identification of Specific Components of the Eicosanoid Biosynthetic and Signaling Pathway Involved in pathological inflammation during Intra-abdominal Infection with Candida albicans and Staphylococcus aureus. Infect Immun :
Ikeh, Mélanie A C; Fidel Jr, Paul L; Noverr, Mairi C (2018) Prostaglandin E2 Receptor Antagonist with Antimicrobial Activity against Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 62:
Lilly, Elizabeth A; Ikeh, Melanie; Nash, Evelyn E et al. (2018) Immune Protection against Lethal Fungal-Bacterial Intra-Abdominal Infections. MBio 9:
Hall, Rebecca A; Noverr, Mairi C (2017) Fungal interactions with the human host: exploring the spectrum of symbiosis. Curr Opin Microbiol 40:58-64
Jabra-Rizk, Mary Ann; Kong, Eric F; Tsui, Christina et al. (2016) Candida albicans Pathogenesis: Fitting within the Host-Microbe Damage Response Framework. Infect Immun 84:2724-39
Lown, Livia; Peters, Brian M; Walraven, Carla J et al. (2016) An Optimized Lock Solution Containing Micafungin, Ethanol and Doxycycline Inhibits Candida albicans and Mixed C. albicans - Staphyloccoccus aureus Biofilms. PLoS One 11:e0159225
Nash, Evelyn E; Peters, Brian M; Fidel, Paul L et al. (2016) Morphology-Independent Virulence of Candida Species during Polymicrobial Intra-abdominal Infections with Staphylococcus aureus. Infect Immun 84:90-8
Bruno, Vincent M; Shetty, Amol C; Yano, Junko et al. (2015) Transcriptomic analysis of vulvovaginal candidiasis identifies a role for the NLRP3 inflammasome. MBio 6:
Nash, Evelyn E; Peters, Brian M; Palmer, Glen E et al. (2014) Morphogenesis is not required for Candida albicans-Staphylococcus aureus intra-abdominal infection-mediated dissemination and lethal sepsis. Infect Immun 82:3426-35
Peters, Brian M; Palmer, Glen E; Nash, Andrea K et al. (2014) Fungal morphogenetic pathways are required for the hallmark inflammatory response during Candida albicans vaginitis. Infect Immun 82:532-43

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