NEW ORLEANS – As antimicrobial-resistant infections continue to inspire the search for modern cures, microbiologists are also looking to some ancient and unexpected corners of the world for progress. Alligator blood, cockroach brains and even commercial yogurt may harbor bug-beating elements, recent research presented at ASM Microbe 2017 suggests. All explorations were early in their progress. But each offers tantalizing invitations to further research.
A study from Purdue University, Northwest (PNW) showcased alligator serum's power to inhibit the growth of several human pathogens, including Escherichia coli, Salmonella, and Staphylococcus. Though alligator blood was already known to be a potent antimicrobial, the mechanism for making it that way has been largely unknown. To begin to uncover that secret, PNW professor Lindsay Gielda supervised a study led by then-undergraduate Nate Poling, who exposed 28 species of bacteria to sera from alligator, cat, dog, duck, boa constrictor, turtle, lobster and opossum.
Out of all bacterial strains tested, the alligator serum showed the most antimicrobial potential – except when it came to one pathogen: Serratia marcescens, a pathogen known for causing septicemia in alligators. The reason for that, the scientists hypothesized, is a special nitrogen regulation system in S. marcescens that is able to escape a mechanism alligators have evolved over millions of years to limit nitrogen availability in their blood, thus inhibiting most bacterial growth, since all organisms need nitrogen to survive.
"A lot of antimicrobials take a 'target-and-kill' approach" Gielda told BioWorld Today. "What if we can have some kind of factor that steals nutrients away?" Determining that could eventually help lead to the discovery of either new antimicrobials or synergistic combination therapies, she said.
BRAWNY BRAINS
Though research into sourcing powerful therapies from the natural world has tended to focus on plants and animals, another study presented during the meeting noted that insects also represent a plentiful and untapped potential source of new antimicrobials.
Research conducted by scientists in Malaysia and Pakistan took that idea to its logical end, putting cockroaches to the test – or at least cockroach parts. Reasoning that the insects have a deserved reputation as one of the hardiest creatures on earth and are routinely exposed to all kinds of wastes and pathogenic microbes, they dissected and extracted cockroach body parts to test against both S. aureus and neuropathogenic E. coli K1. Cockroach brain lysates, they found, exhibited both high antibacterial activity and were nontoxic to human cells. Out of hundreds of compounds present in the brain extracts, only 20 different compounds were identified, 18 of which appeared to possess broad-spectrum antimicrobial, anticancer and analgesic properties, they said.
The research was conducted by Salwa Mansur Ali, of Sunway University in Malaysia, and Ruqaiyyah Siddiqui, an assistant professor at the University of Karachi in Pakistan.
TASTIER THAN BUGS?
For those averse to bugs fighting bugs, researchers at Howard University offered a potentially more palatable set of results. They found that a Lactobacillus isolate from commercial yogurt, identified as Lactobacillus parafarraginis, inhibited growth of several multidrug-resistant and extended spectrum beta-lactamase bacteria from patients in a Washington hospital.
In light of the current rise of antibiotic resistance in hospitals, said Rachelle Allen-McFarlane, a doctoral candidate in the biology department at Howard, findings from the yogurt study may hold promise for therapeutic applications.
No studies regarding how sick a patient might need to be to imbibe alligator blood or eat cockroach brains were reported during the meeting. U.S. yogurt sales, also not featured in any studies at ASM, topped $7.7 billion in 2015.
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