Molecular Identification and Genotyping of Pseudomonas aeruginosa Isolates Using Double-Locus Sequence Typing (DLST) Analysis

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Hemin Esmael Othman


Pseudomonas aeruginosa, antibiotic sensitivity, PCR, DLST, Phylogenetic analysis.


     The opportunistic pathogen Pseudomonas aeruginosa is responsible for many life-threatening nosocomial and environmental acquired infections. In this study, the antibiotic susceptibility, molecular identification and genotyping of P. aeruginosa were performed. A total of 100 isolates of P. aeruginosa out of 523 specimens (19.12%) from clinical and environmental sources were analyzed. The results of antibiotic sensitivity profile grouped these isolates into non-multidrug resistant (non-MDR), multidrug resistant (MDR), and extensively drug resistant (XDR) by the ratios of 23.7%, 40.5% and 35.6%, respectively. The double-locus sequence typing (DLST) scheme was employed for genotyping a collection of 36 isolates of P. aeruginosa recovered from different clinical and environmental sources. Isolates were successfully typed into 19 different DLST genotypes with high discriminatory power (0.9206). In addition, three new alleles were recognized for the locus ms172 namely; ms172-128, ms172-129 and ms172-130. Thus, three novel DLST genotypes of this pathogen have been identified, which were previously not reported, with the combinations of DLST128-60, DLST129-79 and DLST130-17, respectively. All new genotypes, which were exclusively belonged to the clinical sources, were exhibited XDR pattern. The phylogenetic analysis differentiated these genotypes into seven different genetic clusters supported by strong bootstrap values. However, there were indications of distinct evolutionary origins for some of the un-clustered genotypes (5/8). The DLST type 32-39 was the predominant cluster in this region with a majority of XDR pattern. Hereby, it can be concluded that DLST was capable of discriminating the phenotypically and genetically related isolates of P. aeruginosa and offered a reliable phylogenetic analysis.

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