Antimicrobial activity and time kill curve study of newly synthesized dialkyl carboxylate cyclohexane derivative; A novel anti-Pseudomonas aeruginosa compound

Abstract

Pseudomonas aeruginosa causes nosocomial infections, ventilator-associated pneumonia and high morbidity and mortality in immunocompromised and cystic fibrosis patients. Development of the high level of resistance to multiple antibiotics and lack of new drugs accentuate the need of new antimicrobial substances against this opportunistic pathogen. A novel dimethyl carboxylate cyclohexane derivative was synthesized and initially screened against four Gram-positive bacteria and four Gram-negative bacteria by agar well diffusion method. Minimum inhibitory concentration (MIC) was determined against all test pathogens using resazurin dye by broth microdilution method. Effect of test compound on growth curve of Pseudomonas aeruginosa BDU-49 was evaluated by turbidimetric method. Time kill assay was performed to assess bacteriostatic or bactericidal nature and relationship between the concentration of the test compound and the net growth rate of Pseudomonas aeruginosa BDU-49. Test compound exhibited better antimicrobial activity against Gram-negative bacteria. Pseudomonas aeruginosa BDU-49 was the most susceptible test culture with MIC 62.5 μg mL^-1. The growth curves of Pseudomonas aeruginosa BDU-49 demonstrated that test compound could inhibit the growth and reproduction of bacteria. Time kill assay showed that test compound is bactericidal at 2× MIC and bacteriostatic at MIC. Overall, these data indicate that test substance could act as probable novel anti-Pseudomonas aeruginosa compound in future.