Person: KORTEN, VOLKAN
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KORTEN
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VOLKAN
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Publication Unknown Susceptibility of bacterial isolates from Turkey - A report from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program(TAYLOR & FRANCIS LTD, 2007) KORTEN, VOLKAN; Eraksoy, H.; Basustaoglu, A.; Korten, V.; Kurt, H.; Ozturk, R.; Ulusoy, S.; Yaman, A.; Yuce, A.; Zarakolu, P.The study monitored the susceptibility of nosocomial pathogens to meropenem and comparator antimicrobial agents isolated as part of the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program from Turkish university hospitals. In terms of minimum inhibitory concentration 90% (MIC90) values, meropenem was two- and eight-fold more active than imipenem against Escherichia coli and Klebsiella pneumoniae, respectively. 40.5% of K. pneumoniae, 23.1% of Klebsiella oxytoca and 15.3% of E. coli isolates were extended-spectrum P-lactamase (ESBL) producers. Piperacillin/tazobactam was the most active agent against isolates of Pseudomonas aeruginosa, followed by meropenem and imipenem. Against Acinetobacter baumannii isolates, meropenem and imipenem were the most active agents. Continued surveillance by the MYSTIC Program appears to be prudent to help focus on effective empiric treatment regimens.Publication Unknown Vancomycin and daptomycin minimum inhibitory concentration distribution and occurrence of heteroresistance among methicillin-resistant Staphylococcus aureus blood isolates in Turkey(BIOMED CENTRAL LTD, 2013-12) KORTEN, VOLKAN; Sancak, Banu; Yagci, Server; Gur, Deniz; Gulay, Zeynep; Ogunc, Dilara; Soyletir, Guner; Yalcin, Ata Nevzat; Dundar, Devrim Ozturk; Topcu, Ayse Willke; Aksit, Filiz; Usluer, Gaye; Ozakin, Cuneyt; Akalin, Halis; Hayran, Mutlu; Korten, VolkanBackground: The aim of this study was to determine the distribution of vancomycin and daptomycin MICs among methicillin-resistant Staphylococcus aureus (MRSA) blood isolates, the prevalence of heterogeneous vancomycin-intermediate S. aureus (hVISA) and the relationship between hVISA and vancomycin MIC values. Methods: A total of 175 MRSA blood isolates were collected from seven university hospitals in Turkey. All isolates were tested for susceptibility to vancomycin and daptomycin by reference broth microdilution (BMD) and by standard Etest method. BMD test was performed according to CLSI guidelines and Etest was performed according to the instructions of the manufacturer. All isolates were screened for the presence of the hVISA by using macro Etest (MET) and population analysis profile-area under the curve (PAP-AUC) methods. Results: The vancomycin MIC50, MIC90 and MIC ranges were 1, 2, and 0.5-2 mu g/ml, respectively, by both of BMD and Etest. The daptomycin MIC50, MIC90 and MIC ranges were 0.5, 1 and 0.125 -1 mu g/ml by BMD and 0.25, 0.5 and 0.06-1 mu g/ml by Etest, respectively. The vancomycin MIC for 40.6% (71/175) of the MRSA isolates tested was >1 mu g/ml by BMD. No vancomycin and daptomycin resistance was found among MRSA isolates. Percent agreement of Etest MICs with BMD MICs within +/- 1 doubling dilution was 100% and 73.1% for vancomycin and daptomycin, respectively. The prevalence of hVISA among MRSA blood isolates was 13.7% (24/175) by PAP-AUC method. MET identified only 14 of the hVISA strains (sensitivity, 58.3%), and there were 12 strains identified as hVISA that were not subsequently confirmed by PAP-AUC (specificity, 92.1%). Conclusions: Agreement between BMD and Etest MICs is high both for vancomycin and daptomycin. Daptomycin was found to be highly active against MRSA isolates including hVISA. A considerable number of isolates are determined as hVISA among blood isolates. As it is impractical to use the reference method (PAP-AUC) for large numbers of isolates, laboratory methods for rapid and accurate identification of hVISA need to be developed.Publication Unknown Colistin nephrotoxicity in critically ill patients after implementation of a new dosing strategy(J INFECTION DEVELOPING COUNTRIES, 2019-10-31) KORTEN, VOLKAN; Ozel, Ayse Serra; Ergonul, Onder; Korten, VolkanIntroduction: Intravenous colistin is increasingly used to treat multidrug-resistant Gram-negative infections. Highly variable nephrotoxicity rates have been reported. Recent PK/PD studies propose a loading dose and a maintenance dose for better efficacy, but data on the renal toxicity of such regimens are rare. This study aimed to evaluate the incidence and risk factors for nephrotoxicity related to colistin after implementation of a new dosing regimen including a loading dose. Methodology: This was a prospective observational study that was made between adult patients who received a minimum of 48 hours of intravenous colistin from December 2012 to January 2014 at the medical and surgical intensive care units (ICU) of a university hospital. The severity of acute kidney injury (AKI) was defined by the RIFLE criteria. Results: Fifty-nine patients met the inclusion criteria, and 31 (52.5%) developed nephrotoxicity. The APACHE-II score was > 15 in 81% of patients. The median time to nephrotoxicity was 7 days. Patients with AKI were in risk (10.2%), injury (16.9%), failure (25.4%), and none of the patients developed permanent renal insufficiency. A logistic regression model identified three predictors of colistin-associated nephrotoxicity: age; the number of days that estimated target plasma concentrations of colistin were >= 3.5 mg/L in the first week of therapy; and baseline creatinine level. Conclusion: In this cohort of severely ill ICU patients, colistin led to a relatively high rate of nephrotoxicity. Further studies are needed to identify the optimal dose for both efficacy and safety.Publication Unknown Risk factors, characteristics, and outcomes of candidemia in an adult intensive care unit in Turkey(MOSBY-ELSEVIER, 2017) ÖZBEN SADIÇ, BESTE; Tigen, Elif Tukenmez; Bilgin, Huseyin; Gurun, Hande Perk; Dogru, Arzu; Ozben, Beste; Cerikcioglu, Nilgun; Korten, VolkanThirty-six patients with candidemia and 37 control patients were included consecutively to determine the characteristics of candidemia episodes. The patients with candidemia had higher mortality with higher Sequential Organ Failure Assessment scores and frequency of use of a central venous catheter, total parenteral nutrition, and broad-spectrum antibiotics; chronic renal failure with replacement therapy; and longer stay in an intensive care unit. Candida albicans was the predominant species followed by Candida glabrata, Candida tropicalis, and Candida parapsilosis. All isolates of C glabrata were itraconazole-resistant. (C) 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.