Anxious to avoid returning to a situation similar to that existing before the discovery of penicillin, the scientific community has spent years searching for a solution to the problem of growing antibiotic resistance. Dr. Manuel J. Rodríguez, a microbiologist at the University of Córdoba, started to examine the effects of rhodomyrtone as an antibiotic for the treatment of infections caused by Streptococcus pneumoniae, a Gram-positive bacterium commonly known as pneumococcus.
Rhodomyrtone is a molecule extracted from the leaves of Rhodomyrtus tormentosa, a medicinal plant growing in south-east Asia whose activity against Gram-positive bacteria was reported by a Thai research group. In the light of its antimicrobial properties, Dr. Rodríguez decided to take the research one step further, by assessing its possible antibiotic effect against strains of pneumococcus, the bacterium responsible for pneumonia, meningitis, bronchitis and sinusitis.
His research focussed on confirming the efficacy of rhodomyrtone against pneumococcal strains and on determining the dose-rate necessary to kill the bacterium or inhibit its growth, in order to provide society with a new weapon in the fight against pneumococcal diseases at a time when growing resistance has impaired the efficacy of currently-used antibiotics.
With a view to confirming its antibiotic effect and pinpointing its potential future use, the research team sought to find out more about the molecular mechanism behind rhodomyrtone’s antibacterial action.
Proteomic and metabolomic analyses were performed to chart changes in the behaviour of enzymes and metabolites in pneumococcus strains exposed to rhodomyrtone. Findings revealed changed behaviour in some of the enzymes and metabolites involved in the synthesis of the pneumococcal capsule, a mucous layer enveloping the pathogen which is in itself a virulence factor.
The study concluded that rhodomyrtone is indeed effective against pneumococcus, and that its molecular mechanism of action involves the weakening or complete removal of the pathogen’s protective capsule.
This research highlights the fact that the fight against microbial disease is not a single battle but rather an ongoing war. Natural selection, the process by which pathogens acquire resistance to antibiotics, will also prompt the scientific community to keep up its guard, since antibiotics which are effective today may no longer be efficacious in 40 or 50 years’ time.
Mitsuwan, W; Olaya-Abril, A; Calderon-Santiago, M; Jimenez-Munguia, I; Gonzalez-Reyes, JA; Priego-Capote, F; Voravuthikunchai, SP; Rodriguez-Ortega, MJ. Integrated proteomic and metabolomic analysis reveals that rhodomyrtone reduces the capsule in Streptococcus pneumonia. SCIENTIFIC REPORTS.