Comparative Analysis of Phenotypic and Genetic Resistance of Pseudomonas aeruginosa Clinical Isolates to Antimicrobial Drugs

Background. The World Health Organization has included Pseudomonas aeruginosa in the list of multidrug-resistant bacteria which urgently requires the development of new antibiotics and regulation of the use of existing ones. The aim of the study was to identify and evaluate the correlation of phenotypic and genetic resistance of clinical isolates of P. aeruginosa isolated from patients in the Republic of Tatarstan. Methods . 40 clinical isolates of P. aeruginosa from patients in the Republic of Tatarstan were studied. Susceptibility to antimicrobial drugs was assessed using the disk diffusion method. The presence of resistance genes was tested using polymerase chain reaction. Results. Phenotypic resistance to beta-lactam antibiotics was detected in 85–100% of clinical isolates of P. aeruginosa out of 40 studied. Moreover, 38% of isolates carried the mexB gene for resistance to beta-lactam antibiotics. Resistance to fluoroquinolones was shown by 80% of isolates, and resistance to aminoglycosides was detected in 45–55%. The mexD gene associated with resistance to fluoroquinolones was identified in 20% of isolates. The aminoglycoside resistance genes ( mexY, aac(3)-IIa, aphA1, rpsL) were detected in 3–50% of P. aeruginosa isolates , respectively. Conclusion. The presented results indicate a discrepancy between the phenotypic manifestation of resistance and the presence of antibiotic resistance genes. This indicates the presence of many mechanisms of resistance to the same groups of antibiotics, which should be taken into account when developing complex drugs to overcome bacterial resistance to the drug. At the same time, isolates with a low level of expression of genetic resistance determinants are susceptible to the antibiotic and pose a threat of spreading resistance genes.