Reviewed by Lily Ramsey, LLM

In a recent review published in the Microorganisms Journal, researchers reviewed existing data on the use of probiotics and antimicrobial peptides (AMPs) against multi-drug-resistant (MDR) bacteria, emphasizing vancomycin-resistant Enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA).

Study: Probiotics and Their Bioproducts: A Promising Approach for Targeting Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus. Image Credit: Helena Nechaeva/Shutterstock.com

Background

Antibiotic resistance, notably against MRSA and vancomycin-resistant Enterococcus, is a major public health concern worldwide.

Conventional therapy for these illnesses is difficult and frequently necessitates alternate medications with poor effectiveness, greater costs, and negative side effects. As a result, new antibiotic-resistant bacteria-fighting tactics are urgently required.

About the review

In the review, researchers presented probiotics and AMPs as alternatives or adjuncts to conventional antimicrobials against MRSA and VRE infections.

Conventional treatment options and associated challenges

MDR bacterial infections provide major hurdles to traditional antibiotic treatment. Many antibiotics are toxic, resulting in altered pharmacokinetics in critically ill patients, a lack of standardized therapeutic medication monitoring, and an increase in the frequency of widely resistant and pan-drug-resistant strains due to inadequate antimicrobial stewardship measures.

Antibiotic susceptibility testing in microbiology laboratories is difficult for gram-negative and gram-positive species. MRSA and VRE are two of the most difficult Gram-positive bacteria to cure.

Treatment is determined by the patient's hospitalization status and the location of the infection. Oral antibiotics include Clindamycin, TMP-SMX, doxycycline, minocycline, and linezolid.

Intravenous (IV) vancomycin, daptomycin, telavancin, and oral or IV clindamycin or linezolid are appropriate alternatives for more severe SSTI in hospitalized patients.

Vancomycin or daptomycin are indicated for MRSA bacteremia and infective endocarditis, with linezolid and clindamycin replacing daptomycin for MRSA pneumonia.

Daptomycin, linezolid, tedizolid, teicoplanin, dalbavancin, telavancin, oritavancin, and various tetracycline derivatives are all effective against VRE.

The American Heart Association recommends linezolid or daptomycin for VRE-caused infective endocarditis. Daptomycin plus ampicillin or ceftaroline may be used for persistent bacteremia caused by VRE endocarditis.

Use of probiotics to combat antibiotic-resistant bacteria

Probiotics and antimicrobial peptides (AMPs) are potential treatments for acute infectious diarrhea, necrotizing enterocolitis, acute respiratory tract infections, infantile colic, and antibiotic-associated diarrhea.

Probiotics can affect the host immune system, limit pathogen growth and adhesion, break biofilms, and improve the function of the intestinal barrier. They are effective against Clostridioides difficile-associated, travelers, and viral diarrheas caused by antibiotics.

Probiotics may also be useful in combating developing resistant infections because they inhibit pathogen growth, disrupt biofilm formation, and interfere with quorum sensing. S. aureus growth was suppressed by Bifidobacterium strains derived from older persons, which improved host immune system activation.

Fungal biofilm development may promote resistance to antifungal medicines while protecting the fungus from immune cells. Lactobacillus strains such as L. acidophilus, L. casei, and L. plantarum were found to be antibacterial against several strains of S. aureus.

Lactic acid-producing bacteria create bioactive compounds that impair quorum sensing in bacteria, enhancing antibiotic sensitivity.

Bacteriocins, such as Micasin, have been shown to inhibit Gram-positive and Gram-negative bacteria, including MRSA. Lactis generated nisin, a bacteriocin that decreased fecal VRE levels by up to 2.5 times.

Probiotic lactobacilli were discovered to aid in the elimination of chronic MRSA carriage in people's noses and throats. Treatment with L. rhamnosus may diminish MRSA colonization in oropharyngeal, nasal, intestinal, and axillary locations.

Individuals who were provided yogurt containing L. rhamnosus cleared their VRE, while S. boulardii and E. coli Nissle therapy avoided VRE outbreaks in a facility for early rehabilitation.

Nisin inhibits cell wall formation, whereas mersacidin inhibits gram-positive bacteria and food-borne diseases by inducing the cell wall stress response.

Conclusions

Overall, the review findings highlighted the efficiency of probiotics against MDR bacteria such as MRSA and VRE and their potential as an alternative to conventional antibiotics or adjuvant treatment.

However, issues such as standardized TDM techniques and appropriate target antibiotic doses persist. The increasing prevalence of MDR and pan-drug-resistant microorganisms necessitates the development of novel and safer therapies.

Probiotics and their bioproducts can enhance mucus barrier integrity, inhibit MDR bacteria growth, prevent biofilm formation, disrupt quorum sensing, and regulate host immunological responses to pathogens.

Standardization of production techniques, appropriate regimens, and safety in immunocompromised and frail patients are the key challenges with probiotic usage in patients.

Since AMPs made with probiotic strains do not acquire tolerance to microorganisms, they may be a useful alternative to live probiotics for individuals with compromised immune systems.

Natural AMPs, on the other hand, are prone to proteolytic breakdown and have limited oral bioavailability, necessitating compositional changes to make them more resistant to degradation and acceptable for oral administration.

Journal reference:

• Jain, M.; Stitt, G.; Son, L.; Enioutina, E.Y. (2023) Probiotics and Their Bioproducts: A Promising Approach for Targeting Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus. Microorganisms. doi: 10.3390/ microorganisms11102393. https://www.mdpi.com/2076-2607/11/10/2393