Investigating the ALGD gene expression under antibiotics stress in Pseudomonas aeruginosa

Obviously, P. aeruginosa is a multi-drug pathogen equipped with wide range of virulence factors. Alginate represented one of important virulence factors of P. aeruginosa being acts as an extracellular matrix material of biofilm; a matter complicates and increase the therapeutic challenge. Consequently, the present study aimed to detecting the amount of algD gene expressed under the stress of antibiotics. Thus, controlling algD gene expression may reduce the capacity of P. aeruginosa to establish biofilm; thereby reduce the therapeutic challenge. A total of 175 clinical specimens were collected, only 50 isolates were identified as P. aeruginosa. However, the highest percentage of isolation were 56% and 44% from burn and wound specimens, respectively. A Disk Diffusion method showed that the resistance to Amikacin was the most frequent (36%), followed by Ceftazidime (24%), Gentamicin (22%), Cefepime (18%), and finally Imipenem (2%). What's more, all isolates were sensitive to Ciprofloxacin and Meropenem. Most isolates developed MIC of 128 µg /mL. of interest, all isolates of P. aeruginosa in this study formed biofilm; where, 38, 9, and 3 isolates developed weak, moderate, and strong biofilms, respectively. PCR study revealed that out of 15 P. aeruginosa isolates, algD was detected in 10 isolates. Albeit all these ten isolates presented a reduced biofilms when treated with Amikacin at sub-MIC, the results of qPCR demonstrated that the algD was upregulated in six isolates (PA8, PA35, PA47, PA49, PA39, PA44) and in the other four isolates (PA1, PA19, PA27, PA36) showed a downregulation in the expression of algD.