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RESISTANCE AND VIRULENCE GENE PROFILES IN KLEBSIELLA PNEUMONIAE AND ACINETOBACTER BAUMANNII STRAINS ISOLATED FROM HOSPITALIZED PATIENTS

D. MIHAI, M. C. CHIFIRIUC, I. GHEORGHE, L. DITU, G. MIHAESCU
Wednesday 19 December 2018 by Libadmin2018

ABSTRACT

Klebsiella pneumoniae and Acinetobacter spp. strains are opportunistic pathogens frequently involved in the etiology of nosocomial infections in immunocompromised patients. A major factor amplifying the risk of these infections is prolonged period of hospitalised patients, especially in intensive care units. Statistically, the strains belonging to the Enterobacteriaceae family and those of the Acinetobacter spp. are ranked the first and respectively, the second among Gram negative bacilli, whose incidence has increased significantly in last years. The impact of increasingly aggressive multidrug-resistant strains of K. pneumoniae and A. baumannii, due to their ability to acquire genes encoding resistance to antibiotics has raised interest in understanding the mechanisms which control the various stages of the infection, in order to achieve effective control and prevention of these infections. The purpose of this study was represented by the screening of resistance and virulence genes screening carried out on a total of 21 K. pneumoniae and 28 A. baumannii strains. The PCR reaction was performed on total DNA extracted by alkaline lysis from 24 h cultures in 20 ml NaOH (0.05M) + SDS (0.025%). The amplicons’ presence was checked by gel electrophoresis in agarose gel and staining with ethidium bromide 3.5 μg/ml.
Results. All K. pneumoniae strains were positive for blaCTX-M and TEM genes encoding for extended spectrum beta-lactamases (ESBL) and for blaNDM and blaOXA48 encoding for carbapenemases. The quinolone resistance gene QnrS was evidenced in 57.14% of the strains, while QnrA and QnrB in 14.28% of the analyzed strains. The mrkA and ecpRAB involved in biofilm development were evidenced in 42.85% and 14.28% of the strains, respectively. In A. baumannii strains there was revealed the presence of intrinsic OXA-51 β-lactamase in 21.42% and the acquired OXA-23 carbapenemase in 25% of the strains, respectively. Aminoglycoside resistance was demonstrated by the presence of AphA6 and AphA1 genes encoding for phosphotransferases (25%) and respectively, for acetyltransferases (14.28%). In terms of virulence and pathogenicity, the A. baumannii harboured genes involved in biofilms’ formation, respectively encoding for ompA porin, found in 32.14% and for EPSA in 25% of the tested strains.

Keywords: Klebsiella pneumoniae, Acinetobacter baumannii, resistance genes, biofilm.


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