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Research spotlight

September 2019

Alexander Fleming’s discovery of penicillin in the 1920s paved the way to new and widely used therapeutic drugs to treat infections — antibiotics. A century later, we are now facing one of the biggest battles in global health: multi-drug resistant superbugs and limited antibiotics to control them.

Antibiotic resistance is one of the world’s most urgent public health problems, threatening not only human health but also animals and our food supply. In the United States alone, at least 2 million people are infected with antimicrobial resistant bacteria each year and more than 23,000 of them die from these infections, according to the Centers for Disease Control and Prevention.

Mohamed Seleem, professor of microbiology and head of the Microbiology, Immunology and Molecular Genetics Section in the Purdue University College of Veterinary Medicine, is seeking practical solutions to the global threat of antimicrobial resistance. In partnership with researchers around the world, he is developing quicker diagnostic methods to identify superbugs, new and repurposed antibiotics to treat them, and alternative therapeutics.

Improved diagnosis

One critical area of superbug research is bloodstream infections (BSIs), which are widespread and fatal. “In the U.S. alone, BSI affects more than one million people every year, causing significant mortality ranging from 28 to 50%,” Seleem says. Many bacteria and fungi, once entering the bloodstream, can multiply rapidly throughout the entire body.

“In current clinical practice, patients suspected of having a bloodstream infection are initially treated with broad-spectrum antimicrobials that, in many instances, are not necessary, and can harm the patient and contribute to the emergence of antimicrobial-resistant pathogens,” he says. Meanwhile, cultures of blood specimens can take from one to five days. “For every hour of delay in starting correct antimicrobial therapy, the risk of death for a given patient with sepsis increases by six to 10%,” he explains.

Seleem and Ji-Xin Cheng at Boston University are developing a microsecond-scale stimulated Raman spectroscopic imaging platform to enable the quick identification of a single bacterium or fungus directly from a blood sample. By measuring the unique vibrational footprints of molecules, their technology detects microbes and analyzes their response to antimicrobial drugs in minutes instead of days (Hong et al, 2018; Karanja et al, 2017). If further research bears out, the new imaging platform could save time and lives.

New and repurposed drugs

To help ensure a steady supply of defenses against constantly evolving superbugs, Seleem is partnering with researchers around the world on new drug development. Among his most successful projects to date has been a collaboration with Abdelrahman Mayhoub of Zewail University, Egypt, which led to the discovery of phenylthiazoles (Mohammad et al, 2014; Mohammad et al, 2017). This new class of antibiotics is effective against multidrug resistant strains of Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant S. aureus (VRSA), Vancomycin-intermediate S. aureus (VISA) and Vancomycin-resistant Enterococcus (VRE). Seleem has secured a patent and obtained research funding from the National Academy of Sciences and Showalter Research Trust to further pursue this line of research.

In another project, Seleem is working with research faculty in Purdue’s Department of Veterinary Clinical Sciences to repurpose two existing medications for controlling chronic eye and ear infections. The drugs are currently undergoing clinical trials. “Developing a new antibiotic is time-consuming, with an average time of 15 years from the time of inception,” Seleem explains. “Repurposing saves time and money, as these drugs have already gone through safety trails.”

Alternative therapeutics

Public health advocates are increasingly encouraging the prudent use of antibiotics to combat antibiotic resistance, but viable alternatives are still needed. Seleem’s team has developed a new tool to treat MRSA infections that is reminiscent of a light saber from “Star Wars.” In laboratory studies, they discovered that bacteria exposed to blue light were rendered weak enough to be killed by mild antiseptics — and unlike ultraviolet light, the light appears to be safe on human skin.

Seleem is now collaborating on development of a portable device, similar to a small flashlight, which shines blue light on areas of the skin infected with MRSA. The technology has been patented through Purdue’s Office of Technology Commercialization. His collaborator at Boston University, Cheng, is working to arrange clinical trials through BU.

Writers: Aparna Desai Nemali,; Angela Roberts,

Source: Dr. Mohamed Seleem,

Spotlight archives: August 2019


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