Tıp Fakültesi / Faculty of Medicine
Permanent URI for this collectionhttps://hdl.handle.net/11727/1403
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Item In Vitro Efficacy of Ceftazidime-avibactam Against blaOXA-48-producing Klebsiella pneumoniae Isolates(2023) Cag, Yasemin; Kocoglu, Mucahide Esra; Caskurlu, Hulya; Haciseyitoglu, Demet; Mirza, Hasan Cenk; Guclu, Aylin Uskudar; Cetinkaya, Riza Aytac; Vahaboglu, Haluk; 0000-0002-8853-3893; F-1232-2015Introduction: The healthcare burden of carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) infections is growing. The newly developed beta-lactam/beta-lactamase inhibitor combination, ceftazidime-avibactam, shows promise in the treatment of such infections. We aimed to explore the in vitro efficacy of ceftazidime-avibactam against carbapenem-resistant K. pneumoniae isolates carrying the blaOXA-48 gene.Materials and Methods: The isolates were identified using MALDI-TOF MS (Brucker, USA). The isolates that were non-susceptible to imipenem, meropenem, or ertapenem by the disk diffusion method using the European Committee of Antimicrobial Susceptibility Testing (EUCAST) breakpoints were screenes. Minimum inhibitory concentration (MIC) values were determined via broth microdilution according to the EUCAST criteria. A time-kill study was performed according to Clinical and Laboratory Standards Institute guidelines. Beta-lactamase genes were screened for using polymerase chain reaction with previously published primers.Results: A total of 129 K. pneumoniae isolated between April 2011 and February 2021 were studied. Of these, 98, 23, and eight isolates carried the blaOXA-48, blaNDM, and blaOXA-48 with blaNDM genes, respectively. All isolates carrying the blaNDM gene were resistant to ceftazidime-avibactam. Approximately 79.6% of the blaOXA-48-positiveisolates were susceptible to ceftazidime-avibactam. The time-kill study for ceftazidime-avibactam was performed with one blaOXA-48-positive isolate (MIC, 4 mg/l). Ceftazidime-avibactam time-kill kinetics were evaluated in multiples of MIC. There was a decrease of >= 3-log10 in CFU/ml count at a concentration of 8, 16, and 32 MIC at 6 hours. The minimum bactericidal concentration was 8 mg/l.Conclusion: Ceftazidime-avibactam is an important treatment alternative alternative for blaOXA-48 positive carbapenem-resistant K. pneumoniae infections. The most rational approach to the treatment of carbapenem-resistant K. pneumoniae infections appears to be the initiatiion of targeted therapy according to culture antibiogram results or revision of the empirically initiated combination or monotherapy as early as possible according to culture antibiogram results.Item Antibacterial Resistance in Lower Respiratory Tract Bacterial Pathogens: A Multicenter Analysis from Turkey(2021) Guclu, Aylin Uskudar; Kocak, Aylin Altay; Ok, Mehtap Akcil; Tutluoglu, Bulent; Basustaoglu, Ahmet; 0000-0002-1872-028X; 0000-0002-0451-0142; 33690209; AAU-6196-2020; AAI-8012-2021Introduction: This study aimed to evaluate the etiology of lower respiratory tract infections (LRTIs) and their antibiotic resistance. Methodology: Bacterial culture results of LRT samples from 17 hospitals between 2016-2019 were included in the study. All isolates were identified and AST were performed by automated microbiology systems. AST was performed according to EUCAST. Results: Non-duplicate 30,051 (26,890 HA and 3156 CA) isolates detected as causative pathogen. LRTIs are caused by 85.1% Gram-negative bacterial pathogens and 14.9% Gram-positive. The most common isolates among HA pathogens were Acinetobacter spp. (27.4%), P. aeruginosa (22.2%), K. pneumoniae (17.9%); among CA pathogen S. pneumoniae (19.9%), P. aeruginosa (18.9%), H. influenzae (14.6%). ESBL rate was 62.5% in K. penumoniae; 53.1% in E.coli; 19.1% in Klebsiella spp; 13.9% in Enterobacter spp.; 8.6% in Proteus spp.; 6.3% in Citrobacter spp.; and 4.3% in Serratia spp. Resistance rates to carbapenems and colistin were 92.8% and 12.8% in A baumannii, 39.8% and 7.5% in P. aeruginosa, 47.3% and 18.5% in K. penumoniae. Among staphylococci, 27.3% of S. aureus and 82.4% of CoNS were methicillin resistant. 7.6% of E.faecium and 0.9% of E. faecalis were vancomycin resistant. Linezolid resistant S. aureus, CoNS, E. faecalis and E. faecium rates were 0.3%, 2.9%, 0.0% and 4.6%. Inducible clindamycin resistant rate was 17.2% in S. aureus 38.2% in CoNS. Non-susceptible S. pneumoniae isolate rate to penicillin was 37.0%. 6.5% of S. maltophilia and 4.4% of B. cepacia isolates were resistant to trimethoprim/sulfamethoxazole. Conclusions: Antibiotic resistance was mainly observed among A. baumannii and K. pneumoniae and continuous surveillance of antimicrobial resistance patterns in the management of LRTIs is important.Item 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-8012-2021Objectives: 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.