Microbiology, Antibiotics and Public Health

Shorena Khetsuriani has completed her PhD at Tbilisi State Medical University (TSMU). She is an Associate Professor of Microbiology Department of TSMU. She has published more than 80 papers in different biomedical journals. She is a co-author of two textbooks and three methods recommendations (for students and young researchers in biomedical field). She was the Supervisor of doctoral dissertation in Microbiology and a Peer Reviewer in microbiology issues of articles for biomedical journals. She is the Vice-President of NGO “Biomedical Research Development Association” and the Member of American Society for Microbiology.

Staphylococcus aureus is one of the most prevalent causative agents of infections and linked to increasing mortality associated with multidrug resistance worldwide. This bacterium is an important cause of endovascular infections, pneumonia, osteomyelitis, septic arthritis, skin and soft tissue infections, endocarditis, foreign-body infections and sepsis. S. aureus is a common cause of infections in patients in intensive care units in many countries. One of the reasons for the success of this human pathogen is its variability, occurring at different times and countries. The aim of study was to identify frequency of multidrug-resistance S. aureus (MDRSA) strains isolated from different sites of patients with various infections, to determine prevalent body sites. The average age of patients was 40 years. Strains were examined according to morphological, microscopical, tinctorial parameters. Cultivation of S. aureus were performed on different media (meat-peptone agar, meat-peptone broth, 5% blood agar, egg yolk-salt agar, milk-salt agar); cultivation ability was also studied according to temperature, biochemical properties (carotenoid pigment formation, carbohydrate fermentation, enzyme activity) and antibiotic susceptibility tests. Study results showed that the most prevalent site was oral cavity-MDRSA cultured in 19.35±2.98% cases. By comparison, isolation was not significantly different for pharyngeal and soft tissue infections (the same number for both sites-14.44±2.93%). There were detected a few and equal number of isolation cases from peritoneal liquid and phlegmon samples (both- 2.15±1.42%). In other cases number of isolated strains varied between above mentioned data (skin and soft tissue infection-6.09±2.25%, nasal cavity-5.73±2.10%, eye-4.65±2.01%, ear-3.94±1.87%, trachea-3.94±1.87%, urine-3.58±1.79%).

Warren Chanda is a Young Researcher in the field of Microbiology and affiliated with Tropical Diseases Research Centre, Zambia. He is a holds an MSc in Microbiology from Dalian Medical University and BSc in Biomedical Sciences from the University of Zambia. He has much interest in bacteriology and focuses his researches in understanding the host-pathogen interaction, understanding biofilm formation with antimicrobial resistance, and novel drug discovery. He is currently working on understanding the prevalence of poverty-related infections such as tuberculosis and diarrheal diseases, and their drug resistant patterns. His research interests include bacterial biofilm formation, host-pathogen interaction, antimicrobial resistance and novel drug discovery.

Pseudomonas aeruginosa is a ubiquitous Gram negative opportunistic pathogen capable of causing severe nosocomial infections in humans, and tobramycin is currently used to treat P. aeruginosa associated lung infections. Quorum sensing regulates biofilm formation which allows the bacterium to result in fatal infections forcing clinicians to extensively use antibiotics to manage its infections leading to emerging multiple drug resistant strains. As a result, tobramycin is also becoming resistant. Despite extensive studies on drug discovery to alleviate microbial drug resistance, the continued microbial evolution has forced researchers to focus on screening various phytochemicals and dietary compounds for antimicrobial potential. Linolenic acid (LNA) is an essential fatty acid that possesses antimicrobial actions on various microorganisms. It was hypothesized that LNA may affect the formation of biofilm on P. aeruginosa and improve the potency of tobramycin. To prove this hypothesis, crystal violet staining assay for biofilm formation and alamarblue cell viability staining assay for biofilm metabolic activity were employed. Quorum sensing, biofilm and virulent factor gene expression levels were analysed with quantitative real time PCR. Phenotypic assays such swarming motility, pyocyanin production, LasA staphylolytic activity and azocasein protease production were also analysed. The present study demonstrated that LNA interfered with cell to cell communication and reduced virulence factor production. It further enhanced the potency of tobramycin and synergistically inhibited biofilm formation through P. aeruginosa quorum sensing systems. Therefore, LNA may be considered as a potential agent for adjunctive therapy and its utilization may decrease tobramycin concentration in combined treatment thereby reducing aminoglycoside adverse effects.