In this study 86 isolates of Vibrio cholerae were analysed for their adhesive properties and the presence of pathogenicity island genes. With the exception of three isolates, all of the other clinical isolates (92.5 %) contained an intact TCP (toxin-co-regulated pilus) gene cluster. In contrast, 95 % of all environmental non-O1-non-O139 isolates were negative for the TCP gene cluster. The majority of clinical isolates (82.5 %) possessed the complete vibrio pathogenicity island (VPI) gene cluster and had a similar RFLP pattern, while only a single environmental strain possessed an almost complete VPI cluster (lacking 0.4 kb in the tcpA and toxT region). The result showed that the isolates with tcpA + /toxT + had a strong attachment for HT-29 and Vero cells, whereas isolates with tcpA + /toxT " or tcpA " /toxT " genomic characteristics showed no autoagglutination and weak attachment for the cell lines. Two environmental strains (tcpA " /toxT " ) showed strong adhesive properties to the cell lines, indicating that non-fimbrial adhesive factors are involved in the environmental V. cholerae strains in the absence of TCP.
The emergence of a single environmental isolate in our study containing the pathogenicity genes amongst the diverse non-pathogenic environmental isolates needs to be further studied in the context of V. cholerae pathogenicity sero-coversion.
Background and Objectives: The aim of this study was to evaluate the antibacterial and antibiofilm activity of recombinant
Azurin from Pseudomonas aeruginosa against different bacterial species.
Materials and Methods: The azurin gene was cloned in the pET21a vector. The pET21a-azurin construct was transformed into Escherichia coli BL21. The recombinant Azurin was expressed and purified using affinity chromatography and con- firmed by Western blotting. The cytotoxicity of rAzurin was assessed on peripheral blood mononuclear cells. Antibacterial and antibiofilm activity of rAzurin with different concentrations were determined by micro-broth dilution and crystal violet methods, respectively. The effect of rAzurin on bacterial species was statistically analyzed by t- test and spearman correla- tion.
Results: The identity of purified protein was confirmed by blotting and distinguished as a 14 kDa band on 15% SDS-PAGE. The IC50 of rAzurin on Peripheral Blood Mononuclear Cell (PBMC) was determined as 377.91±0.5 µg/mL in 24 h. Vibrio cholerae and Campilobacter jejuni displayed the most sensitivity to rAzurin (27.5 and 55 μg/mL, respectively) and the highest resistance (220 μg/mL) was displayed by P. aeruginosa and E. coli. The MIC for other species was 110 μg/mL. The Minimum Biofilm Inhibition Concentration (MBIC) was determined as 220 μg/mL for Salmonella enterica and V. cholerae,
300 μg/mL for Shigella sonnei, Shigella flexneri and P. aeruginosa and 440 μg/mL for the other species. The antimicrobial effect of rAzurin on bacterial species were significant (p value<0.05) and correlation coefficient was negative.
Conclusion: The rAzurin appears to be an appropriate choice and a new strategy for prevention of bacterial infection. It
inhibits bacterial growth and biofilm formation and candidates as antimicrobial peptides.
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