Biological Evaluation of Selected 1,2,3-triazole Derivatives as Antibacterial and Antibiofilm Agents

BACKGROUND

Resistance to antimicrobial agents is a major public health problem, being Staphylococcus aureus prevalent in infections in hospital and community environments and, admittedly, related to biofilm formation in biotic and abiotic surfaces. Biofilms form a complex and structured community of microorganisms surrounded by an extracellular matrix adhering to each other and to a surface that gives them even more protection from and resistance against the action of antimicrobial agents, as well as against host defenses.

METHODS

Aiming to control and solve these problems, our study sought to evaluate the action of 1,2,3- triazoles against a Staphylococcus aureus isolate in planktonic and in the biofilm form, evaluating the activity of this triazole through Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. We have also performed cytotoxic evaluation and Scanning Electron Microscopy (SEM) of the biofilms under the treatment of the compound. The 1,2,3-triazole DAN 49 showed bacteriostatic and bactericidal activity (MIC and MBC 128 μg/mL). In addition, its presence interfered with the biofilm formation stage (1/2 MIC, p <0.000001) and demonstrated an effect on young preformed biofilm (2 MICs, p <0.05).

RESULTS

Scanning Electron Microscopy images showed a reduction in the cell population and the appearance of deformations on the surface of some bacteria in the biofilm under treatment with the compound.

CONCLUSION

Therefore, it was possible to conclude the promising anti-biofilm potential of 1,2,3-triazole, demonstrating the importance of the synthesis of new compounds with biological activity.

Synthesis of benzoylthiourea derivatives and analysis of their antibacterial performance against planktonic Staphylococcus aureus and its biofilms

Following the appearance of several antimicrobial agents to control the spread of infections, two major challenges have emerged: (i) the occurrence and blowout of multiresistant bacteria and the increase of chronic diseases and (ii) difficult-to-eradicate infections. In this study, we tested five benzoylthiourea derivatives for their ability to inhibit and stop bacterial growth and evaluated the possible influence of 1,2,4-triazolyl-benzoylthiourea derivative 4 on the formation and eradication of Staphylococcus aureus biofilms. Benzoylthiourea derivatives 4, 6, 10, 11 and 13 were obtained in one or two steps with low cost and subjected to tests to identify their minimum inhibitory concentration (MIC) and minimum bactericidal concentration. In vitro tests were also performed to assess their effects on biofilm formation and in preformed biofilms and scanning electron microscopy was used to visualize the effects on biofilm formation. The 1,2,4-triazolyl-benzoylthiourea derivative 4 showed bacteriostatic activity against the S. aureus HU25 clinical strain with an MIC of 16 µg ml^-1 , which is below the toxic concentration (at 2500 µg ml^-1 , 62·25% of the cells remained viable). Compound 4 also effectively prevented biofilm formation at the three subinhibitory concentrations tested (1/2 MIC, 1/4 MIC and 1/8 MIC) as confirmed by scanning electron microscopy. For breakdown of formed biofilms, the main influence was at a subinhibitory concentration (1/2 MIC). These findings make compound 4 a strong candidate for studies on the development of new antimicrobial and antibiofilm agents.

Emergence of methicillin-resistant Staphylococcus aureus from clonal complex 398 with no livestock association in Brazil

CC398 is a livestock-associated Staphylococcus aureus. However, it has also been isolated from humans with no previous contact with livestock. A surveillance of methicillin-resistant S. aureus colonisation among children attending public day care centres and hospitals in Niterói and Rio de Janeiro, Brazil, between 2011 and 2013, resulted in the isolation of six cases of CC398 from individuals with no previous exposure to livestock. These isolates showed a high frequency of the erm(C) gene (4/6, 66.7%) with induced resistance to clindamycin, and a relatively high frequency of SEs and lukS/lukF genes. These results suggest the emergence of a non-LA-CC398 in Brazil.