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Investigating a novel contact-dependent killing system and its contribution to pathogen dominance in the urinary tract

Award Number: R21AI173594
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 12/16/2022
PERIOD OF PERFORMANCE END DATE: 11/30/2024

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Investigating a novel contact-dependent killing system and its contribution to pathogen dominance in the urinary tract - PROJECT SUMMARY Escherichia coli and Proteus mirabilis are important urinary tract pathogens and the most common causes of catheter-associated urinary tract infections (CAUTIs). CAUTIs are one of the most common health care- associated infections and contribute to nearly double the mortality rate of catheterized compared to non- catheterized patients. CAUTIs are frequently polymicrobial and inter-species interactions contribute to the development of catheter biofilms and increase the risk of sepsis. Polymicrobial environments are shaped by both cooperative and competitive interactions between species. However, specific interactions between different urinary tract colonizers currently remain poorly defined. Characterizations of competitive interactions is additionally hampered by the fact that a large number of competition systems remain undiscovered. Our overall goal is to study the role of competition systems for successful colonization of Enterobacteriaceae in the urinary tract. This proposal specifically aims to identify and further characterize a novel inter-species competition system employed by Proteus mirabilis to kill competitor species. We showed that clinical and commensal P. mirabilis strains quickly and drastically (2-million-fold) reduced viability of E. coli and other Enterobacteriaceae during co-culture. Cell-free P. mirabilis culture supernatant alone did not reduce viability of target cells. Killing instead required direct contact between cells. However, a heat-labile component in stationary phase P. mirabilis supernatant was sufficient to induce killing, suggesting that the system is likely regulated via quorum sensing. Killing also occurred on solid surfaces, where P. mirabilis was able to penetrate and kill all cells in established microcolonies of E. coli. This highlights a potential role of the killing system in mixed biofilms, which is an important component of urinary catheter colonization and persistence. The only known contact-dependent competition system in P. mirabilis is the Type 6 Secretion System (T6SS), but a mutant deficient in this system still killed E. coli. We thus hypothesize that P. mirabilis employs a novel contact-dependent system to kill E. coli cells. The objective of this study is to identify the killing system and its regulation, define the mechanism of action, and elucidate the role of the killing system for competition of P. mirabilis with E. coli during polymicrobial infections in vivo. In Aim 1, we will use a transposon library of P. mirabilis and a bioluminescence-based assay to screen for P. mirabilis mutants unable to kill E. coli and to identify genes coding for effector molecules, delivery system and regulatory molecules of the killing system. We will also test the hypothesis that quorum sensing molecules regulate the activity of the system and investigate the mechanism of how E. coli cells die after contact with P. mirabilis. In Aim 2 we will assess the role of the P. mirabilis killing system during polymicrobial infection. We will first test the ability of P. mirabilis to kill E. coli during biofilm formation on urinary catheters and then assess colonization of catheters and dissemination to peripheral organs for P. mirabilis and E. coli in single and polymicrobial infections using a CAUTI mouse model.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2024 ( Subtotal = $194,238 )
2024	2024	UNIVERSITY OF ILLINOIS	809 S MARSHFIELD AVE M/C 551	CHICAGO	IL	60612	COOK	USA	Allergy and Infectious Diseases Research	000	2	11/17/2023	NON-COMPETING CONTINUATION	$174,815
2024	2024	UNIVERSITY OF ILLINOIS	809 S MARSHFIELD AVE M/C 551	CHICAGO	IL	60612	COOK	USA	Allergy and Infectious Diseases Research	001	2	6/13/2024	NON-COMPETING CONTINUATION	$19,423
														Subtotal = $194,238

Issue Date FY: 2023 ( Subtotal = $244,446 )
2023	2023	UNIVERSITY OF ILLINOIS	809 S MARSHFIELD RM 520	CHICAGO	IL	60612	COOK	USA	Allergy and Infectious Diseases Research	000	1	12/16/2022	NEW	$244,446
														Subtotal = $244,446

Grand Total All Awards = $438,684

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Investigating a novel contact-dependent killing system and its contribution to pathogen dominance in the urinary tract

Award Number: R21AI173594

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 12/16/2022

PERIOD OF PERFORMANCE END DATE: 11/30/2024

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