Browsing by Author "Yayla, Buket"

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    AMINOGLYCOSIDE RESISTANCE DETERMINANTS IN MULTIRESISTANT ESCHERICHIA COLI AND KLEBSIELLA PNEUMONIAE CLINICAL ISOLATES FROM TURKISH AND SYRIAN PATIENTS
    (2019) Cirit, Osman Sezer; Fernandez-Martinez, Marta; Yayla, Buket; Martinez-Martinez, Luis; 30803254
    Escherichia coli and Klebsiella pneumoniae are frequently found resistance to aminoglycosides in Turkey. The aim of this study was to investigate aminoglycoside resistance in clinical isolates of E. coli and K. pneumoniae from Turkey using both phenotypic and genotypic methods and screening for the prevalence of gene coding for common aminoglycoside-modifying enzymes (AMEs) and 16S rRNA methylase genes. A total of 88 consecutive, non-duplicated E. coli (n = 65) and K. pneumoniae (n = 23) isolates showing resistance or intermediate resistance to amikacin and/or gentamicin were collected between October 2013 and May 2015 from clinical samples received at Gaziantep Dr. Ersin Arslan Training and Research Hospital. Seventeen isolates were obtained from Syrian patients. Isolates resistant to any of the two aminoglycosides were tested by PCR for seven AME genes, and 22 isolates with amikacin MIC >= 16 mg/L were also tested for 16S rRNA methylase genes. In E. coli isolates, the most frequent genes were aac(6')-Ib (50 strains; 76.9%) and aae(3)-Ha (40 strains; 70.7%), followed by aph(3)-Ia (5 strains; 7.6%) and ant(2 '''')-Ia (2 strains; 3.1%). Among the 23 resistant K. pneumoniae isolates, the most prevalent gene was aae(3)-Ha (87.0%) followed by aac(6')-Ib (73.9%) and aph(3')-Ia (8.6%). The rmtC gene was detected in one K. pneumoniae isolate. Resistance to aminoglycosides in clinical isolates of E. coli and K. pneumoniae from our center is predominantly caused by AAC(6')-Ib and AAC(3)-II enzymes, while the occurrence of 16S rRNA methylases is so far limited.
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    In vitro activity of ceftolozane-tazobactam and ceftazidime-avibactam against clinical isolates of meropenem-non-susceptible Pseudomonas aeruginosa: A two-centre study
    (2020) Mirza, Hasan Cenk; Hortac, Elvan; Kocak, Aylin Altay; Demirkaya, M. Hamiyet; Yayla, Buket; Guclu, Aylin Uskudar; Bustaoglu, Ahmet; 0000-0002-1872-028X; 0000-0002-8853-3893; 0000-0002-0451-0142; 0000-0002-4335-6897; 31568882; AAU-6196-2020; F-1232-2015; AAI-8012-2021
    Objectives: This study aimed to compare the activity of ceftazidime-avibactam (C/A), ceftolozane-tazobactam (C/T) and three anti-pseudomonal beta-lactams (piperacillin-tazobactam, ceftazidime and cefepime) against a collection of meropenem-non-susceptible Pseudomonas aeruginosa (P. aeruginosa) clinical isolates recovered from two centres in Turkey. Methods: A total of 102 unique patient isolates of meropenem-non-susceptible P. aeruginosa were included in the study. MICs of antimicrobials were determined by the gradient diffusion method. Results: Overall susceptibility rates for C/A and C/T were 83.3% and 82.4%, respectively. Both C/A and C/T had better activity than any one of the three anti-pseudomonal beta-lactams. According to the MIC50 values, C/T was the most potent agent against isolates. Although the susceptibility rates of isolates to C/T and C/A were similar, C/T (MIC50, 1 mg/mL) was four-fold more potent than C/A (MIC50, 4 mg/mL). The MIC50 values of C/A and C/T for the isolates that were non-susceptible to three beta-lactams were significantly higher than those for isolates that were non-susceptible to zero, one or two beta-lactams. Also, the C/A MIC50 value for the isolates that were non-susceptible to two beta-lactams was higher than that for isolates which were non-susceptible to one beta-lactam. Conclusions: C/A and C/T showed good activity against meropenem-non-susceptible P. aeruginosa isolates. However, resistance to these agents was not uncommon among these isolates. The overall beta-lactam susceptibility profile of isolates seems to have an effect on the probability of susceptibility to C/A and C/T. Antimicrobial susceptibility testing should be performed for C/A and C/T if these agents are considered for treatment of infections caused by meropenem-non-susceptible P. aeruginosa. (C) 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd.