Cinnamaldehyde: a compound with antimicrobial and synergistic activity against ESBL-producing quinolone-resistant pathogenic Enterobacteriaceae

AbstractUsage of cephalosporin and quinolone antibiotics has aggravated the development of extended-spectrum beta-lactamase (ESBL) –producing quinolone-resistant (QR) pathogenicEnterobacteriaceae. The present study aims to determine antimicrobial activity of cinnamaldehyde alone or in combination with cefotaxime/ciprofloxacin to reverse the drug resistance and evaluations of efficacy, and possible molecular mechanism of action of the combination was also evaluated using in vitro assays. Broth microdilution assay was used to determine minimum inhibitory concentrations (MICs) of cinnamaldehyde and antibiotics against ESBL-QREnterobacteriaceae. Synergistic effect and dynamic interaction with antibiotics were further examined by checkerboard assay, isobologram analysis, and time-kill assay, respectively. Cellular morphology of bacteria was viewed with scanning electron microscopy (SEM). Effects of cinnamaldehyde and its combination on the expression of gene encoding —porins (ompC,ompF,ompK35, andompK36), efflux pump genes (acrB –E. coli,acrB –K. pneumoniae), and antibiotic-resistant genes (blaTEM,blaSHV,blaCTXM, andQnrB) were evaluated using real-time quantitative PCR (RT-qPCR). Majority of theE. coli (32.1%) andK. pneumoniae (24.2%) isolates demonstrated MIC of cinnamaldehyde at 7.34  μg/mL and 0.91 g/mL, respectively. Synergism between cinnamaldehyde and cefotaxime was noted among 75%E. coli and 60.6%K. pneumoniae. Similarly, synergism with ciprofloxacin was observed...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research