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Permanent URI for this collectionhttps://hdl.handle.net/11443/932

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Author: search.filters.author.Karatuna, Onur

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    Six-year distribution pattern of hepatitis C virus in Turkey: a multicentre study
    (TAYLOR \& FRANCIS LTD, 2016-01-01) Altindis, Mustafa; Dal, Tuba; Akyar, Isin; Karatuna, Onur; Gokahmetoglu, Selma; Ulger, Seda Tezcan; Kulah, Canan; Uzun, Berrin; Sener, Asli Gamze; Ozdemir, Mehmet; Aydogan, Sibel; Kuskucu, Mert Ahmet; Midilli, Kenan; Otlu, Baris; Celen, Mustafa Kemal; Buruk, Kurtulus; Guducuoglu, Huseyin
    Hepatitis C infection is a public health problem. The aim of this retrospective study was to determine the distribution of hepatitis C virus (HCV) genotypes in seven regions of Turkey, by evaluating 7002 patients with chronic HCV in a six-year period. During the 2009-2014 period, serum/plasma samples from 7002 new consecutive HCV RNA positive patients were collected. The female patients were 3867 (55.2\%). The genotype distribution of HCV patiens was evaluated by ages and years. Statistical analysis was performed by using the Mann-Whitney test and the chi(2) analysis. During the six-year period, genotype 1b was the most common genotype (67.7\%) followed by untypeable genotype 1 (7.7\%), genotype 4 (7.3\%) and genotype 3 (6.7\%). In 2014, genotype 3 was the second most common one (11.3\%) and genotype 4 was the third most common one (9.8\%). In the group with <25 years old patients, genotype 1b was most common (78.48\%, 62/79) between the years of 2009 and 2011, whereas genotype 3 (34.8\%, 86/247), between the years of 2012 and 2014. Genotype 1b was the most common in the groups between 26 and 35 years, 36 and 45 years, 46 and 55 years, 56 and 65 years. The rate of genotype 3 was increased from 4.78\% to 10.06\% and the rate of genotype 4 was increased from 1.3\% to 3.84\%, from 2009-2011 to 2012-2014. In recent years, genotypes 3 and 4 have gained importance. New therapeutic strategies and survey studies may be required for the modified HCV genotype pattern.
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    Antimicrobial Susceptibility Test for the Determination of Resistant and Susceptible S. aureus and Enterococcus spp. Using a Multi-Channel Surface Plasmon Resonance Device
    (MDPI, 2019-01-01) Ucak Ozkaya, Gulsum; Durak, Muhammed Zeki; Akyar, Isin; Karatuna, Onur
    The objective of this study was to investigate the development of a surface plasmon resonance (SPR) sensor platform equipped with multiple channels for the simultaneous determination of methicillin-resistant S. aureus (MRSA), methicillin-susceptible S. aureus (MSSA) and vancomycin-resistant Enterococcus (VRE), and vancomycin-susceptible Enterococcus (VSE). Drug resistance of S. aureus strains against cefoxitin and Enterococcus strains against vancomycin were investigated both using the minimum inhibitory concentration method (MIC) assay and the SPR system equipped with single and multiple channels. The MIC values of MRSA and MSSA ranged from 32 mu g/mL to >128 mu g/mL and from 1 mu g/mL to 4 mu g/mL, respectively. The MIC values of VRE and VSE were between 64 to >128 mu g/mL and 2-4 mu g/mL, respectively. With the multiple-channel system, the angle shifts of MRSA, MSSA, VRE and VSE were found to be -0.030 degrees and -0.260 degrees, -0.010 degrees and -0.090 degrees respectively. The antibiotic-resistant and susceptible strains were distinguished within 3 h for S. aureus strains and within 6 h for Enterococcus strains.
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    The carbapenem-resistant Enterobacteriaceae threat is growing: NDM-1 epidemic at a training hospital in Turkey
    (BMC, 2016-01-01) Karabay, Oguz; Altindis, Mustafa; Koroglu, Mehmet; Karatuna, Onur; Aydemir, Ozlem Akkaya; Erdem, Ali Fuat
    Background: Recently, new carbapenemases in Enterobacteriaceae strains and non-fermentative gram-negative bacilli have been reported. The New Delhi metallo-beta-lactamase-1 (NDM-1) is a major problem around the world. The purpose of this article is to address the NDM-1 Klebsiella pneumoniae epidemic detected in eight cases in our hospital. Methods: Bacteria identified in this epidemic were from patients already admitted to the intensive care unit of the Sakarya University Training and Research Hospital during efforts toward establishment of infection surveillance and control program. Antimicrobial susceptibility testing of strains was performed using the VITEK 2 system (bioMerieux, France), E-test gradient strips (bioMerieux, France), and the disc diffusion test. For the metallo-beta-lactamase activity, the combined disc diffusion test and modified Hodge test as phenotypic tests were performed. To identify the resistance gene, the Xpert Carba-R kit (Cepheid Inc., USA) and an in-house multiplex polymerase chain reaction (PCR) method designed for five common carbapenemase genes (IMP, VIM, KPC, NDM-1, and OXA-48) were employed. The clonal relationship of these strains was explored by the repetitive PCR (rep-PCR, DiversiLab System, bioMerieux, France) method. Results: During the December 2014 to March 2015 period, NDM-1 positive K. pneumoniae strains were detected in eight patients. All of these strains were found to produce NDM-1, while two of them also revealed the presence of OXA-48. The rep-PCR results reveal a clonal proximity of 95 \% for six of the eight strains. Conclusions: Our findings suggest the tendency of NDM-1-producing strains to spread in our country as well. A carbapenem-resistant K. pneumoniae threat may pose a great risk to our country. It is clear that more comprehensive infection control precautions should be implemented in our hospitals.
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    The use of matrix-assisted laser desorption ionization-time of flight mass spectrometry in the identification of Francisella tularensis
    (ASSOC BASIC MEDICAL SCI FEDERATION BOSNIA \& HERZEGOVINA SARAJEVO, 2016-01-01) Karatuna, Onur; Celebi, Bekir; Can, Simge; Akyar, Isin; Kilic, Selcuk
    Francisella tularensis is the cause of the zoonotic disease tularemia and is classified among highly pathogenic bacteria (HPB) due to its low infection dose and potential for airborne transmission. In the case of HBP, there is a pressing need for rapid, accurate and reliable identification. Phenotypic identification of Francisella species is inappropriate for clinical microbiology laboratories because it is time-consuming, hazardous and subject to variable interpretation. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was recently evaluated as a useful tool for the rapid identification of a variety of microorganisms. In this study, we evaluated the use of MALDI-TOF MS for the rapid identification of Francisella tularensis and differentiation of its subspecies. Using national collection of Francisella isolates from the National Tularemia Reference Laboratory (Public Health Institution of Turkey, Ankara), a total of 75 clinical isolates were investigated by species and subspecies-specific polymerase chain reaction (PCR) test and MALDI-TOF MS. All isolates were originally identified as F. tularensis subsp. holarctica according to region of difference 1 (RD1) subspecies-specific PCR results. For all isolates MALDI-TOF MS provided results in concordance with subspecies-specific PCR analysis. Although PCR-based methods are effective in identifying Francisella species, they are labor-intensive and take longer periods of time to obtain the results when compared with MALDI-TOF MS. MALDI-TOF MS appeared to be a rapid, reliable and cost-effective identification technique for Francisella spp. Shorter analysis time and low cost make this an appealing new option in microbiology laboratories.
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    Evaluation of the Carba NP Test for the Detection of Carbapenemase Activity in Bacteroides Species
    (POLSKIE TOWARZYSTWO MIKROBIOLOGOW-POLISH SOCIETY OF MICROBIOLOGISTS, 2018-01-01) Akyar, Isin; Ayas, Meltem; Karatuna, Onur; Besli, Yesim
    We evaluated the usefulness of the Carba NP test for rapid detection of carbapenemase activity in Bacteroides spp. The minimum inhibitory concentration (MIC) for imipenem was determined with gradient test strips, and cfiA gene was investigated by polymerase chain reaction for 27 clinical Bacteroides spp. isolates. Carba NP test was performed according to recommendations of the Clinical and Laboratory Standards Institute. Among three cfiA gene harboring clinical isolates, two imipenem resistant isolates were Carba NP test positive, while the imipenem intermediate isolate was negative. Our preliminary results suggest that the Carba NP test can be useful as a rapid test to detect carbapenemases in Bacteroides species.