# Mechanisms of Klebsiella pneumoniae gastrointestinal colonization

> **NIH NIH R01** · WAKE FOREST UNIVERSITY HEALTH SCIENCES · 2024 · $612,025

## Abstract

Abstract
Hospital-acquired infections (HAI) resulting from the transmission of drug-resistant pathogens affect hundreds
of millions of patients worldwide. Klebsiella pneumoniae (Kpn), a gram-negative bacterium, is notorious for
causing HAI, with many of these infections difficult to treat as Kpn has become multi-drug resistant.
Epidemiological studies suggest that gastrointestinal (GI) colonization of Kpn is a major reservoir through
which Kpn can cause disease manifestations either in the colonized host or transmit from host to host. This site
of Kpn colonization has not been the focus of previous studies as a tractable model of Kpn GI colonization, and
host-to-host transmission did not exist. We have recently developed a murine model that allows for the study
of Kpn mucosal (oropharynx and GI) colonization, shedding within feces, and transmission through the fecal-oral
route. Using an oral route of inoculation and fecal shedding as a marker for GI colonization, we show
that Kpn can asymptomatically colonize the GI tract of immunocompetent mice and modifies the host GI
microbiota. We premise that specific Kpn genes contribute to its GI colonization, and the products of these genes
could serve as novel targets for the prevention of the establishment of GI colonization. More recently, we used
our murine model to screen a library of Kpn random transposon mutants (In-seq) to identify the complete set of
“GI colonization” genes from a single isolate. A metagenomics sequencing analysis further identified bacterial
species and the metabolic pathways affected by Kpn in the GI tract. Herein, we will focus on two sets of pathways
identified through In-seq whose products allow Kpn to overcome colonization resistance provided by the resident
gut microbiota. Thus, in Aim#1, we will focus on the ethanolamine utilization pathway genes (eut) of Kpn that
allow it to utilize ethanolamine (EA), a byproduct of cellular membranes and diet in the gut that can serve as an
alternative nutrient source. Unlike many other enteric pathogens that contain a single eut operon, Kpn has two
genetically distinct eut operons. We will identify the role of each eut locus in EA metabolism and determine the
underlying molecular mechanism through which EA metabolism provides Kpn with a fitness advantage against
members of the microbiome. Aim#2 will take a different approach by focusing on the contact-dependent killing
machinery of the Kpn (Type 6 secretion system [T6SS]) in overcoming colonization resistance provided by the
resident microbiota. We will focus on the unique regulatory mechanism that modulates the expression
of Kpn T6SS in the GI tract and provide it with a selective and competitive advantage against the resident gut
microbiota. Results from these studies would provide us with a fundamental understanding of the molecular
mechanisms involved in the establishment of GI colonization by an incoming pathogen. These studies will also
lay the groundwork for developing potential...

## Key facts

- **NIH application ID:** 10867402
- **Project number:** 5R01AI173244-02
- **Recipient organization:** WAKE FOREST UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** Muhammad Ammar Zafar
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $612,025
- **Award type:** 5
- **Project period:** 2023-06-14 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10867402

## Citation

> US National Institutes of Health, RePORTER application 10867402, Mechanisms of Klebsiella pneumoniae gastrointestinal colonization (5R01AI173244-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10867402. Licensed CC0.

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