Detection of oqxA and oqxB efflux pump genes among nosocomial coliform bacilli:An observational cross-sectional study

Objectives:To identify and test the antibiotic susceptibility of nosocomial coliform bacilli and investigate the presence of oqxA and oqxB genes among the multidrug-resistant(MDR)phenotypes.Methods:One hundred and twenty different healthcare-associated infection samples were collected.Coliform bacilli were isolated,identified by conventional methods,and then antibiotic susceptibility tests were done using the VITEK2 system and disk diffusion methods.OqxAB operon was identified using a conventional PCR-based technique.oqxA and oqxB genes were compared between MDR Klebsiella pneumonia(K.pneumonia)phenotypes and MDR Escherichia coli(E.coli)phenotypes.Besides,oqxAB operons were compared between phenotypes of K.pneumonia and E.coli isolates.Results:Seventy coliform bacilli were isolated with the predominance of K.pneumonia and E.coli.Besides,82.1%of K.pneumonia strains and 53.3%of E.coli isolates were MDR phenotypes.Significant more oqxB genes alone were found in MDR E.coli than that in MDR K.pneumoniae phenotypes(χ^(2)=10.160,P=0.003).OqxAB operon was significantly more in MDR phenotypes of E.coli than that in the susceptible phenotypes(P<0.001).There was significantly less of this operon in susceptible E.coli isolates than that in susceptible K.pneumoniae isolates(P<0.001).OqxAB positive isolates that were also resistant to fluoroquinolones,tetracycline,trimethoprim,and chloramphenicol,most probably suggested functional pumps.Conclusions:MDR coliform bacilli are strongly implicated in healthcare-associated infection.Attention should be paid to the presence of oqxAB pump,as an important mechanism in the development of resistance against many antimicrobials because it contributes to co-resistance with other categories;therefore,this pump could be a good target for efflux pump inhibitors.

Comparison of inhibitory effect between DL-tryptophan and lactoferrin on Pseudomonas aeruginosa biofilm formation in wound dressing

Objective: To compare the inhibitory effect between DL-tryptophan and bovine lactoferrin on biofilm formed by isolated Pseudomonas aeruginosa strains. Methods: The study was carried out on 40 patients suffering from surgical site infection. Wound pus was collected using sterile swabs after isolation, and identified by common bacteriological methods. Isolated Pseudomonas aeruginosa strains were grown on biofilm enhancing materials, and then the inhibitory effects of different concentrations of DL-tryptophan and lactoferrin were tested using scanning electron microscopy and microtitre plate methods. Results: There was no significant difference in the inhibitory effect between DL-tryptophan and lactoferrin at 0.5 mg/mL. While in concentration of 1 mg/mL and 2 mg/mL, tryptophan showed more significant inhibitory effect than lactoferrin. Conclusions: Both DL-tryptophan and bovine lactoferrin have inhibitory effect on Pseudomonas aeruginosa biofilm formation in a dose dependent manner, and the inhibitory effect of DL-tryptophan is stronger.