Person: DOYMAZ, MEHMET ZIYA
9 results
Search Results
Now showing 1 - 9 of 9
Publication Open Access Discordance between Serum Neutralizing Antibody Titers and the Recovery from COVID-19(2020-09-25T00:00:00Z) Koç, Mm; Kalkan, Yazıcı; Çetin, Nesibe Selma; Doymaz, Mz; Sümbül, B; Durdu, B; YAZICI, MERVE; MERİÇ KOÇ, MELİHA; ÇETİN, NESİBE SELMA; KARAASLAN, ELİF; OKAY, GÜLAY; DURDU, BÜLENT; SÜMBÜL, BİLGE; DOYMAZ, MEHMET ZIYAThe recent pandemic of COVID-19 has caused a tremendous alarm around the world. Details of the infection process in the host have significant bearings on both recovery from the disease and on the correlates of the protection from the future exposures. One of these factors is the presence and titers of neutralizing Abs (NAbs) in infected people. In the current study, we set out to investigate NAbs in the recovered subjects discharged from the hospital in full health. Serum samples from a total of 49 documented consecutive COVID-19 subjects were included in the study. All the subjects were adults, and serum samples collected during the discharge were tested in viral neutralization, enzyme immunoassay (EIA), and Western immunoblot tests against viral Ags. Even though a majority of the recovered subjects had raised significant NAb titers, there is a substantial number of recovered patients (10 out of 49) with no or low titers of NAbs against the virus. In these cohorts as well as in patients with high NAb titers, viral Ag binding Abs were detectable in EIA tests. Both NAb titers and EIA detectable Abs are increased in patients experiencing a severe form of the disease, and in older patients the Ab titers were heightened. The main conclusion is that the recovery from SARS-CoV-2 infection is not solely dependent on high NAb titers in affected subjects, and this recovery process is probably produced by a complex interplay between many factors, including immune response, age of the subjects, and viral pathology.Publication Open Access Screening of mecC Gene in Methicillin Resistant Staphylococcus aureus Isolates(2022-04-01T00:00:00Z) Ceylan, Ayse Nur; SÜMBÜL, BİLGE; DOYMAZ, Mehmet Ziya; SÜMBÜL, BİLGE; DOYMAZ, MEHMET ZIYAObjective: The diagnosis and treatment of mecC positive methicillin resistant Staphylococcus aureus (MRSA) isolates pose a significant problem in clinical microbiology and infectious disease practices. The studies on the frequency of mecC positive isolates in Turkey is rather scarce. In the present study, we aimed to investigate the presence of mecA, mecC, spa and pvu genes in MRSA strains isolated from various clinical specimens submitted to Clinical Microbiology Laboratories of Bezmialem Vakıf Hospital. Methods: We performed nucleic acid extraction and multiplex polymerase chain reaction (PCR) to 126 MRSA strains to detect mecC, mecA, spa and pvl genes. Results: According to the multiplex PCR results of 126 MRSA strains studied, 126 (100%) had mecA, 107 (85%) had spa, and 3 (2%) had pvl genes. We performed another polymerase chain reaction protocol and spa genes were identified in 19 of specimens, which were found negative priorly. Conclusion: Considering the factors that a university medical center where the study was conducted provided a tertiary healthcare service to a large metropolitan area in Istanbul and none of the isolates carried mecC gene might indicate that mecC gene carrying MRSA isolates did not pose a significant public health threat in Turkey.Publication Open Access Immune responses in multiple hosts to Nucleocapsid Protein (NP) of Crimean-Congo Hemorrhagic Fever Virus (CCHFV)(2021-12-01T00:00:00Z) Karaaslan, Elif; Kalkan-Yazıcı, Merve; Hasanoğlu, Sevde; Karakeçili, Faruk; Özdarendeli, Aykut; Kalkan, Ahmet; Kılıç, Ali Osman; Doymaz, Mehmet Ziya; ÇETİN, NESİBE SELMA; DOYMAZ, MEHMET ZIYAIn 2019, the World Health Organization declared 3 billion to be at risk of developing Crimean Congo Hemorrhagic Fever (CCHF). The causative agent of this deadly infection is CCHFV. The data related to the biology and immunology of CCHFV are rather scarce. Due to its indispensable roles in the viral life cycle, NP becomes a logical target for detailed viral immunology studies. In this study, humoral immunity to NP was investigated in CCHF survivors, as well as in immunized mice and rabbits. Abundant antibody response against NP was demonstrated both during natural infection in humans and following experimental immunizations in mice and rabbits. Also, cellular immune responses to recombinant NP (rNP) was detected in multispecies. This study represents the most comprehensive investigation on NP as an inducer of both humoral and cellular immunity in multiple hosts and proves that rNP is an excellent candidate warranting further immunological studies specifically on vaccine investigations.Publication Open Access Hand, Foot, and Mouth Disease Caused by Coxsackievirus A6: A Preliminary Report from Istanbul.(2019-01-01) Ceylan, AN; Turkmen, AV; Turel, O; Gultepe, BİLGE; Inan, E; Doymaz, MEHMET ZİYA; TÜREL, ÖZDEN; SÜMBÜL, BİLGE; VEHAPOĞLU TÜRKMEN, AYSEL; DOYMAZ, MEHMET ZIYAHand, foot, and mouth disease (HFMD) is caused by various serotypes of Enterovirus genus. Coxsackievirus A16 (CV-A16) and enterovirus A71 (EV-A71) were known to be the only responsible agents for these epidemics; however, this opinion was challenged after the detection that coxsackievirus A6 (CV-A6) was the responsible species for the outbreak in Finland in 2008. HFMD is frequently seen in Turkey, and no detailed study on its clinical and microbiological epidemiology has previously been reported. The present study addresses this question. Twenty-seven patient samples collected between 2015 and 2017 were included in the study. Typing was conducted by RT-PCR and the sequencing applied directly to patient's samples and as well as to the viral cultures with pan-enterovirus and serotype-specific primers. The presence of Enterovirus in 12 of 27 HFMD samples was shown with RT-PCR. The causative agent for three of these 12 samples was CV-A16, one of the most frequent two serotypes around the world, and the remaining nine samples was CV-A6. The findings of the study are relevant since it pertains to the molecular epidemiology of HFMD in Turkey, a gateway country where different serotypes might be circulating and transmitted. The findings also support the notion that CV-A6 cases are rising in number, which has caused more severe clinical features and widespread rashes in recent outbreaks. Hand, foot, and mouth disease (HFMD) is caused by various serotypes of Enterovirus genus. Coxsackievirus A16 (CV-A16) and enterovirus A71 (EV-A71) were known to be the only responsible agents for these epidemics; however, this opinion was challenged after the detection that coxsackievirus A6 (CV-A6) was the responsible species for the outbreak in Finland in 2008. HFMD is frequently seen in Turkey, and no detailed study on its clinical and microbiological epidemiology has previously been reported. The present study addresses this question. Twenty-seven patient samples collected between 2015 and 2017 were included in the study. Typing was conducted by RT-PCR and the sequencing applied directly to patient’s samples and as well as to the viral cultures with pan-enterovirus and serotype-specific primers. The presence of Enterovirus in 12 of 27 HFMD samples was shown with RT-PCR. The causative agent for three of these 12 samples was CV-A16, one of the most frequent two serotypes around the world, and the remaining nine samples was CV-A6. The findings of the study are relevant since it pertains to the molecular epidemiology of HFMD in Turkey, a gateway country where different serotypes might be circulating and transmitted. The findings also support the notion that CV-A6 cases are rising in number, which has caused more severe clinical features and widespread rashes in recent outbreaks.Publication Open Access A Current Microbiological Picture of Mycobacterium Isolates from Istanbul, Turkey(2020-01-01T00:00:00Z) Doymaz, MZ; Sumbul, BİLGE; SÜMBÜL, BİLGE; DOYMAZ, MEHMET ZIYADespite advances in diagnosis and treatment, tuberculosis (TB) continues to be one of the essential health problems throughout the world. Turkey is considered to be endemic for TB. In this study, we analyzed the distribution of Mycobacterium species, compare the diagnostic methods, and susceptibilities to anti-tuberculosis drugs of TB isolates. The aim was to document the current status and to provide a frame of reference for future studies. In this study, 278 Mycobacterium species isolated from 7,480 patients between September 2015 and June 2019 were included. Löwenstein-Jensen medium (LJ) and MGIT 960 were used for the isolation of strains. Susceptibility to 1st-line anti-tuberculosis drugs was determined. Positivity rates in clinical samples were as follows: 1.4% for direct microscopic acid-fast bacilli (AFB) detection, 3.4% for growth on the LJ, and 3.7% for growth on MGIT-960. Two hundred thirty-three isolates were identified as Mycobacterium tuberculosis complex (MTBC) and 45 were non-tuberculous mycobacteria (NTMs). Eleven of the NTMs (24.4%) were Mycobacterium fortuitum group isolates, and eight NTMs (17.7%) were Mycobacterium abscessus complex isolates. A number of patients diagnosed with tuberculosis peaked twice between the ages of 20–31 and 60–71. A hundred and eighty-two MTBC isolates (78.1%) were susceptible to all 1st-line anti-tuberculosis drugs, while 51 isolates (21.9%) were resistant to at least one drug tested. The multidrug-resistant tuberculosis rate was 13.7% among resistant strains and 3% in all strains. The liquid cultures were better for detection of both MTBC and NTMs isolates. The data demonstrate that MTBC continues to be challenge for this country and indicates the need for continued surveillance and full-spectrum services of mycobacteriology laboratory and infectious diseases.Publication Open Access Microbiological Diagnosis of COVID-19(2021-02-01T00:00:00Z) SÜMBÜL, BİLGE; DOYMAZ, Mehmet Ziya; SÜMBÜL, BİLGE; DOYMAZ, MEHMET ZIYAVarious tests are used to detect the severe acute respiratory syndrome-coronirus-2 (SARS-CoV-2) virus causing Coronavirus disease-19 (COVID-19) disease. Today, the realtime (RT) -PCR test combined with the reverse-transcription reaction is the gold standard method used to diagnose SARS-CoV-2. This method is referred to as quantitative realtime PCR (RT-qPCR) because it determines not only the presence of SARS-CoV-2 but also the amount of virus in the specimen. Due to the use of virus-specific primers, the specificity of the tests is considered to be 100%. For this test, swab samples taken from the upper respiratory tract such as nasopharyngeal and throat, samples from the lower respiratory tract areas such as sputum and bronchoalveolar lavage fluid, rectal swab, feces, serum and urine samples are preferred. Correct use of personal protective equipment (PPE) by healthcare professionals during sampling and testing is important. Rapid antigen tests used in addition to RT-qPCR test for the diagnosis of SARS-CoV-2 are advantageous due to the theoretical rapid result time and low cost, but the sensitivity of this method is known to be very low. Virus detection in cell cultures can be used to detect SARS-CoV-2, but it is not for routine diagnostic because the results take a long time, require labor, and expertise. Serological tests are frequently used in the diagnosis and follow-up of this disease. These are mainly ELISA, CLIA, immunofluorescence test (IFA), western blot (WB), protein microarray (microarray) and neutralization. ELISA based immunoglobulin (Ig)M and IgG antibody tests have more than 95% specificity in the diagnosis of COVID-19.Publication Open Access Cross-Reactive anti-Nucleocapsid Protein Immunity against Crimean-Congo Hemorrhagic Fever Virus and Hazara Virus in Multiple Species.(2021-01-13T00:00:00Z) Kalkan-Yazıcı, Merve; Karaaslan, Elif; Çetin, Nesibe Selma; Hasanoğlu, Sevde; Güney, Filiz; Zeybek, Ümit; Doymaz, Mehmet Ziya; YAZICI, MERVE; ÇETİN, NESİBE SELMA; DOYMAZ, MEHMET ZIYAThe World Health Organization estimates that there may be three billion people at risk of infection by Crimean-Congo Hemorrhagic Fever Virus (CCHFV), a highly lethal, emerging orthonairovirus carried by ticks. On the other hand, the closely related Hazara virus (HAZV), a member of the same serogroup, has not been reported as a pathogen for humans. Given the structural and phylogenetic similarities between these two viruses, we evaluated the immunological similarities of the nucleocapsid protein (NP) of these two viruses in multiple species. Strong antigenic similarities were demonstrated in anti-NP humoral immune responses against HAZV and CCHFV in multiple species using convalescent human CCHF sera, rabbit and mouse polyclonal antiserum raised against CCHFV, and mouse polyclonal antiserum against CCHFV-NP in enzyme immunoassays. We also report a convincing cross-reactivity between NPs in Western blots using HAZV-infected cell lysate as antigen and inactivated CCHFV and CCHFV-NP-immunized mice sera. These results suggest that NPs of HAZV and CCHFV share significant similarities in humoral responses across species and underline the potential utility of HAZV as a surrogate model for CCHFV.IMPORTANCE CCHFV and HAZV, members of the Nairoviridae family, are transmitted to mammals by tick bites. CCHFV is considered to be a severe threat to public health and causes hemorrhagic diseases with a high mortality rate, and there are neither preventative nor therapeutic medications against CCHFV disease. HAZV, on the other hand, is not a pathogen to humans and can be studied under BSL-2 conditions. The antigenic relationship between these viruses is of interest for vaccines and for preventative investigations. Here, we demonstrate cross-reactivity in anti-NP humoral immune response between NPs of HAZV and CCHFV in multiple species. These results underline the utility of HAZV as a surrogate model to study CCHFV infection.Publication Open Access Distribution of beta-Lactamase Genes Among Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated From Patients in Turkey(2015-11-01) IRAZ, Meryem; Duzgun, Azer Ozad; SANDALLI, Cemal; Doymaz, MEHMET ZİYA; Akkoyunlu, YASEMİN; Saral, Aysegul; PELEG, Anton Y.; OZGUMUS, Osman Birol; BERIS, Fatih Saban; KARAOGLU, Hakan; CICEK, Aysegul Copur; DOYMAZ, MEHMET ZIYA; AKKOYUNLU, YASEMİNBackground: The emergence of carbapenem-resistant Klebsiella pneumoniae poses a serious problem to antibiotic management. We investigated the β-lactamases in a group of carbapenem-resistant K. pneumoniae clinical isolates from Turkey. Methods: Thirty-seven strains of K. pneumoniae isolated from various clinical specimens were analyzed by antimicrobial susceptibility testing, PCR for the detection of β-lactamase genes, DNA sequencing, and repetitive extragenic palindronic (REP)-PCR analysis. Results: All 37 isolates were resistant to ampicillin, ampicillin/sulbactam, piperacillin, piperacillin/tazobactam, ceftazidime, cefoperazone/sulbactam, cefepime, imipenem, and meropenem. The lowest resistance rates were observed for colistin (2.7%), tigecycline (11%), and amikacin (19%). According to PCR and sequencing results, 98% (36/37) of strains carried at least one carbapenemase gene, with 32 (86%) carrying OXA-48 and 7 (19%) carrying NDM-1. No other carbapenemase genes were identified. All strains carried a CTX-M-2-like β-lactamase, and some carried SHV- (97%), TEM- (9%), and CTX-M-1-like (62%) β-lactamases. Sequence analysis of bla(TEM) genes identified a bla(TEM-166) with an amino acid change at position 53 (Arg53Gly) from bla(TEM-1b), the first report of a mutation in this region. REP-PCR analysis revealed that there were seven different clonal groups, and temporo-spatial links were identified within these groups. Conclusions: Combinations of β-lactamases were found in all strains, with the most common being OXA-48, SHV, TEM, and CTX-M-type (76% of strains). We have reported, for the first time, a high prevalence of the NDM-1 (19%) carbapenemase in carbapenem-resistant K. pneumoniae from Turkey. These enzymes often co-exist with other β-lactamases, such as TEM, SHV, and CTX-M β-lactamases.Publication Open Access Actinomyces neuii subsp. neuii Isolated from Perineal Abscess; Case Report(2019-04-01T00:00:00Z) AKBAŞ, EMEL; Sumbul Gultepe, Bilge; ERSÖZ, CEVPER; CEYLAN, AYŞE NUR; DOYMAZ, Mehmet Ziya; AKBAŞ, EMEL; SÜMBÜL, BİLGE; ERSÖZ, CEVPER; CEYLAN, AYŞE NUR; DOYMAZ, MEHMET ZIYAActinomyces are gram positive bacilli which generally colonize in mouth, colon and vagina. The members of genus Actinomyces are facultative anaerobic or microaerophilic organisms and have a branching flamentous structure. They cause classical actinomycosis. Among the Actinomyces species; A. israelii, A. viscosus, A. naeslundii, A. odontolyticus, A. bovis and A. neuii are the mostly isolated organisms from clinical cases. A rarely encountered member of this group, Actinomyces neuii does not show branching and is catalase and CAMP positive and is a coryneform shaped bacillus. Although Actinomyces is mostly found as contaminating organism, in some cases it is reported as a pathogen. Actinomyces neuii has been reported in chorioamnionitis, neonatal sepsis, vertebral osteomyelitis, cervical lymphadenitis, breast abscess, fatal bacteremia and postoperative endophthalmitis. In our case, A. neuii was isolated from a perineal abcess and it was not previously reported. In our case, Actinomyces neuii was identified by commercial identification systems. For this purpose; VITEK MS and VITEK (R) 2 Compact (both by bioMerieux, France) were used in the clinical microbiology laboratory and then this identification was confirmed as the Actinomyces neuii subsp. neuii by the 16S rRNA sequencing. Also, the positivity of CAMP was demonstrated in the laboratory. As in the cases of other actinomycosis, the treatment of the abcess caused by the Actinomyces neuii is through the surgical debridement. The antimicrobial susceptibility testing is not performed since the organism is reported to be susceptibile to common antibiotics. Beta lactam antibiotics are acknowledged as the proper selection for antibiotic treatment.