INVESTIGATION OF ANTIBACTERIAL ACTIVITY OF FIVE HETEROCYCLIC COMPOUNDS AGAINST SOME ORAL STREPTOCOCCAL STRAINS

The oral streptococci are commensal bacteria, but sometimes may be involved in infections which need antimicrobial treatment. In the general context of an increasing incidence of antibiotic resistant isolates, the investigation of the potential antimicrobial activity of different classes of heterocyclic compounds is considered of great interest. The aim of the study was to investigate the antimicrobial activity against 64 clinical isolates of oral streptococci belonging to different species of 5 compounds (Ca, Cb, Cc, Cd and Ce) belonging to the class of: 1,2,4-triazole, 1,3,4-thiadiazole or 1,3,4-oxadiazole, which have been recently reported as newly-synthesized compounds and characterized by spectral and elemental analysis. In the present study, the broth microdilution method was performed to determine the minimum inhibitory concentrations (MIC) of these compounds against the oral streptococci isolates, and afterwards, to determine their minimum bactericidal concentrations (MBC). The values of the MIC ranged between: 32-256 µg/mL for Ca and Cc, 8-256 µg/mL for Cb, 128-256 µg/mL for Cd and 64-256 µg/mL for Ce. The MBC/MIC ratios were less or equal to 4 in all cases. In conclusion, compared to the other 4 compounds, Cb exhibited the highest degree of growth inhibition against the tested strains and might be subjected to further chemical reactions in order to improve its antimicrobial activity. Rezumat Streptococii orali sunt bacterii comensale, insă uneori pot fi implicaţi in infecţii ce ar necesita tratament antimicrobian. In contextul general al cresterii incidenţei izolatelor rezistente la antibiotice, investigarea activităţii antimicrobiene a compusilor heterociclici