Elimination Of Antibiotic Resistance In Pseudomonas Aeruginosa UCP/WFCC 1567 Cadmium Treatment

Pseudomonas aeruginosa is an aerobic bacilli, gram-negative, that can cause nosocomial infections, especially in immune compromised patients. The virulence factors are capable to inactivating the immune system and their infections are particularly problematic as due to intrinsic resistance to multiple classes of antibiotics, or acquiring adaptive resistance during treatment in course. A variety of compounds such as acridine dyes, ethidium bromide, rifampicin, bis ammonium salt, metals such as silver, and more recently, thioridazine a phenothiazine inhibitors like antibiotics B subunit of DNA gyrase, novobiocin and coumermicine have been reported to eliminate plasmid resistant. Some reports described the plasmids by curing inhibitors of DNA gyrase subunit in strains P. aeruginosa . In this work was used clinical P. aeruginosa strain multiresistant (UCP/WFCC 1567) to evaluate the eliminating the antibiotic resistance using the treatment with heavy metal cadmium, until extreme saturation of metal by acclimated strain. The profile of susceptibility to antibiotics of the strain was carried out by Kirb Bauer diffusion method comparing with the wild type , and after the strain was acclimatized twice in Luria Bertani medium containing glucose and added cadmium (32μg/mL). Subsequently, acclimated process of P. aeruginosa was done using cadmium 52μg/mL. After acclimatization a new profile of susceptibility to antibiotics of the strain was carried out Kirb Bauer diffusion method. The first results indicated 84.61% of effective in eliminating plasmidial resistance with 32μg/mL of cadmium treatment. However, when was used acclimatization with for 52 μg/mL of cadmium the elimination was 92.30%, respectivelly. These results obtained suggest the potential of P. aeruginosa (UCP/WFCC 1567) to removal hazards heavy metals processes.

Determination of MIC for cadmium v Acclimation of P. aeruginosa

Determining the MIC was established twice before (for the wild strain) and after acclimatization. The minimum inhibitory concentration (MIC) for a (wild) strain of Pseudomonas aeruginosa was determined by the microdilution method in liquid media (nutrient broth) cadmium at concentrations ranging from 4 to 64 µg/ml, the absence of cadmium being the control. 10μl of the bacterial inoculum were added at a concentration of 10o UFC/ ml to the tubes containing culture medium that were then incubated at 37°C for 24 hours. The MIC was determined after the incubation period by turbidity at 600 nm. The MIC value obtained for the concentration of cadmium was utilized to acclimatize the strain in AN for 120 h at 37°C. After this period, the NIC for cadmium was again determined, the concentrations ranging from 32 to 64 mg/mL, while maintaining the previous conditions, with a new MIC being determined which was 1.625 greater than the MIC of the first acclimatization (Ledeberg and Ledeberg 1952; Pereira et al. (2004). The samples of wild, acclimatized P. aeruginosa with 32 and 52μg/mL of cadmium were subjected to new antibiograms to evaluate the elimination of resistance to drugs by cadmium.

3. Results and Discussion

The results obtained with the antiobiogram of the wild samples, after acclimatzation with 32 and 52μg/mL of cadmium are presented in Table 1.

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