# Combating resistant superbugs by understanding the molecular determinants of target site penetration and binding

> **NIH NIH R01** · UNIVERSITY OF FLORIDA · 2022 · $1,068,186

## Abstract

Project Summary/Abstract
A severe lack of effective antibiotic treatment options against multidrug-resistant (MDR) Gram-negative
bacteria (i.e., “superbugs”) is causing one of the world’s three most serious human health threats. Exacerbating
this is a dramatic decline in the number of new antibiotics effective against MDR Acinetobacter baumannii,
Klebsiella pneumoniae and Pseudomonas aeruginosa. These “superbugs” cause serious bloodstream, respira-
tory and urinary tract, wound, and other infections with very high morbidity and up to 80% mortality. Many
antibiotics have extremely poor penetration to their target site, especially in A. baumannii and P. aeruginosa.
For these antibiotics, the combination of poor target site penetration and extensive efflux causes the antibiotic
concentration at the target site to be over 1,000-fold lower than that of the extracellular antibiotic concentration.
Unsurprisingly, many antibiotic candidates fail because of poor penetration to and/or extensive efflux from their
bacterial target site. Importantly, there are very substantial gaps in the current understanding of how to
maximize the antibiotic target site penetration, avoid efflux from bacterial cells, and thereby maximize receptor
binding. This multi-disciplinary project, however, will identify the molecular determinants of how to maximize
antibiotic target site concentrations and receptor binding to combat resistant “superbugs”. Our preliminary data
and models demonstrate that molecular descriptors can predict the antibiotic target site penetration and effect
of multiple efflux pumps in P. aeruginosa. We have developed a series of assays that characterize the
penetration of key selected antibiotics to their periplasmic or cytosolic target sites and antibiotic binding to their
receptors in intact bacteria. In Aim 1, these new molecular and phenotypic assays will be greatly extended and
applied to all three “superbugs”; additionally, a series of isogenic efflux pump knockout strains will be created.
The resulting data will uniquely inform novel quantitative models (Aim 2) that can predict penetration, efflux,
and thus receptor binding at the bacterial target sites based on molecular antibiotic properties. These models
will enable the targeted synthesis of key selected antibiotic probes (Aim 3) that are used to prospectively
validate these predictive models. These new probes will serve as the backbone of innovative antibiotic combi-
nation dosing strategies that will be rationally optimized via Quantitative and Systems Pharmacology models in
Aim 4. Dynamic in vitro and murine infection models with an intact or compromised immune system will then
prospectively evaluate these combination regimens. These models can simulate antibiotic concentration-time
profiles that mirror those in patients. Overall, this project will provide the molecular insights that enable drug
developers to design new antibiotics that achieve high concentrations at their bacterial target si...

## Key facts

- **NIH application ID:** 10449341
- **Project number:** 5R01AI136803-05
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Jurgen Bernd Bulitta
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $1,068,186
- **Award type:** 5
- **Project period:** 2018-08-10 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10449341

## Citation

> US National Institutes of Health, RePORTER application 10449341, Combating resistant superbugs by understanding the molecular determinants of target site penetration and binding (5R01AI136803-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10449341. Licensed CC0.

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