According to Howard University biologists at the annual American Society for Microbiology meeting held in New Orleans this week, Lactobacillus parafarraginis KU495926, extracted from yogurt, hindered the growth of 14 multidrug resistant and Extended Spectrum Beta Lactamase (ESBL) bacteria obtained from infected patients at a Washington D.C. hospital.
Beta-lactamase enzymes are synthesised by ESBL bacteria, which stimulates resistance to certain broad-spectrum antibiotics. The scientists found that L. parafarraginis, which is a gram-positive microbe, produced bacteriocin which is a type of antimicrobial protein that inhibited the growth of gram-negative ESBL and multidrug resistant bacteria.
Rachelle Allen-McFarlane, senior author and a graduate student in Broderick Eribo’s lab at Howard, is of the opinion that this might be one of the very few known examples of bacteriocins derived from gram-positive bacteria inhibiting the growth of gram-negative bacteria.
Allen-McFarlane told that most of the time the gram-positive kills gram-positive. Usually, bacteriocins from one particular strain are only capable of inhibiting closely related strains.
Allen’s area of interest is to identify bacteriocins from lactic acid bacteria that are capable of inhibiting multi-drug resistant and ESBL gram-negative bacteria. It might be uncommon but it is possible.
To observe whether the metabolic products produced by L. parafarraginis was able to inhibit ESBL and drug-resistant bacteria
, the researchers first demonstrated that metabolites derived from L. parafarraginis could barricade pathogenic growth in culture. Once they showed that this was possible, they confirmed their outcomes using flow cytometry and fluorescent microscopy. These investigations exposed that when certain pathogens, including wound-derived E. coli, were added to media containing L. parafarraginis metabolites, their growth was significantly inhibited.The researchers identified four bacteriocin structural genes in L. parafarragini, using PCR. As a conclusive step, they proved that this bacterium was undeniably capable of producing the proteins.
Allen-McFarlane says, in the future, she hopes to identify the specific bacteriocin produced by L.parafarraginis, and demonstrate how it can inhibit such a broad range of distantly-related pathogens.
