Lactobacillus Isolate Found in Yogurt & Cheese Proves to Have Powerful Antimicrobial Activity

At the recent American Society for Microbiology (ASM) Microbe conference, a team of researchers from Howard University in Washington, DC, presented promising findings on the use of a probiotic isolate from yogurt to fight antibiotic-resistant bacteria.

The escalating public health problem of antibiotic resistance in an era of little drug innovation, was highlighted in a report published last year by the Pew Charitable Trust as part of their Antibiotic Resistance Project. According to the report, no new classes of antibiotics have been discovered since 1984, and all the while bacterial pathogens are gaining new resistance mechanisms against the drugs currently on the market. As a result, the Centers for Disease Control and Prevention (CDC) notes that nearly 2 million people in the United States become infected with drug-resistant bacteria each year, and about 23,000 individuals die as a result of those infections. Although researchers have developed new antibiotics in existing classes, pathogens can develop resistance to multiple drugs within a class, creating an imperative for effective alternatives.

To this end, scientists from Howard University performed research on a potential weapon to fight multidrug-resistant bacteria. In the course of their research, the team analyzed 68 lactic acid bacteria, or Lactobacillus, isolates from cheese and yogurt samples and screened the isolates for antibiotic activity against Staphylococcus aureus, Listeria monocytogenes and Escherichia coli.

Although 93% of the Lactobacillus isolates displayed antimicrobial activity in initial screenings, upon further testing the researchers found that one isolate, Lactobacillus parafarraginis, inhibited 14 multidrug-resistant extended-spectrum beta-lactamase bacteria. These included strains of Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumonia and Enterobacter aerogenes. The team’s initial research indicated that the Lactobacillus isolate inhibits pathogens by producing and releasing an antimicrobial peptide similar to bacteriocin.

“Although the data from our study strongly suggest that the inhibitory agent is a class of bacteriocin, which has been reported to disrupt bacterial cell by targeting lipid II to form pores, further effort is underway in our laboratory to confirm the mechanism of action of the Lactobacillus parafarraginis KU495926 inhibitory agent,” researchers Broderick Eribo, PhD, and Rachelle Allen-McFarlane, a doctoral candidate at Howard, told Contagion^®.

The researchers have not focused their studies on the possible antimicrobial benefits of eating cheese and yogurt; however, they do note that several studies indicate that there are health benefits to consuming lactic acid bacterial species, specifically in cases of diarrheagenic diseases and those of Helicobacter pylori infection. In the scope of the fight against antibiotic-resistant pathogens, the team is continuing their research to help stem the growing public health problem of drug-resistant infections.

“The discovery of novel antimicrobial agents is an exigent matter as many procedures executed by clinicians could become obsolete as they involve administration of antibiotics to which there is an upsurge of resistance,” said Dr. Eribo and Allen-McFarlane. “It is therefore imperative that we accelerate the effort to find novel antimicrobial agents in order to be ahead of the game, otherwise, it is foreseeable that the strides we have made so far to control microbial infections might be negated by the accelerated evolution of the so-called superbugs.”