Begüm Nalça Erdin

Background: Candidozyma auris (C. auris) is an emerging multidrug-resistant yeast associated with healthcare-related transmission, difficult laboratory identification, antifungal resistance, and high mortality in critically ill patients. This study aimed to describe the clinical and microbiological characteristics of early institutional C. auris cases detected in a tertiary hospital in Istanbul, Türkiye. Methods: Adult patients hospitalized between January 2021 and December 2022 with C. auris isolation were retrospectively reviewed. Demographic data, underlying conditions, intensive care unit (ICU) exposure, invasive procedures, antimicrobial and antifungal use, culture sources, antifungal susceptibility testing (AFST) results, and clinical outcomes were evaluated. C. auris isolates were identified using VITEK MS v.3.2, and AFST was performed using C. auris isolates were identified using VITEK MS v.3.2, and AFST was performed using Sensititre YeastOne YO10 (Thermo Fisher Scientific, Waltham, MA, USA) panels. Results were interpreted according to CDC interim breakpoints. Multiple isolates from an individual patient were retained when they represented different specimen types or sampling events. Results: Thirty-three adult patients and 62 clinical isolates were included. The mean age was 67.8 years, and 20 patients (60.6%) were aged 65 years or older. Most patients had prior ICU admission (93.9%), urinary catheterization (97.0%), central venous catheterization (90.9%), mechanical ventilation (81.8%), and broad-spectrum antimicrobial exposure. Blood cultures represented the most frequent source of isolation (56.5%), followed by urine cultures (27.4%). Resistance rates were 98.4% for amphotericin B, 88.7% for fluconazole, 6.6% for micafungin, and 6.5% for caspofungin. Overall mortality was 72.7%. While mortality was numerically higher among patients aged 65 years or older and those requiring inotropic support, only the need for mechanical ventilation was statistically significantly associated with mortality. The cohort-level APACHE II-based expected mortality was 48.0%, whereas observed mortality was 72.7%; this comparison was descriptive and no formal calibration analysis was performed. Conclusions: Early institutional C. auris cases in this tertiary hospital occurred predominantly among elderly, critically ill patients with prolonged healthcare exposure, invasive devices, and extensive antimicrobial use. The findings support the need for early laboratory recognition, cautious interpretation of commercial AFST results, particularly given the propensity of Sensititre YeastOne to overestimate amphotericin B resistance, strengthened infection control practices, and multicenter studies incorporating molecular typing to clarify transmission dynamics and antifungal resistance patterns.

Background: Candida auris has emerged globally as a multidrug-resistant fungal pathogen responsible for healthcare-associated outbreaks and invasive infections. Whole-genome sequencing studies have demonstrated the existence of genetically distinct clades that differ in geographical distribution, antifungal resistance patterns, virulence traits, and outbreak potential. Objectives: This study aimed to evaluate the performance of the ClaID clade identification PCR system among clinical Candida auris isolates collected in İstanbul, Türkiye, and to investigate the clade-associated molecular profiles of circulating isolates. Methods: Forty-four clinical C. auris isolates were analysed using the auris universal sequence (AUS) assay and clade-specific sequence assays (CSS1–CSS5). PCR amplification results were interpreted according to the ClaID framework. Results: AUS amplification was detected in 41/44 isolates (93.2%). CSS1 amplification was observed in 39/44 isolates (88.6%), indicating a predominance of Clade I-associated molecular profiles within this regional İstanbul isolate collection. No amplification was detected using CSS2, CSS3, CSS4, or CSS5 assays. Three isolates were AUS-negative and five isolates did not yield CSS1 amplification despite repeated testing. Conclusions: The findings suggest that the majority of analyzed clinical isolates from İstanbul exhibited Clade I-associated molecular profiles rather than definitive WGS-confirmed clade assignments. This study provides one of the first field evaluations of the ClaID system in a Turkish clinical isolate collection and contributes regional molecular epidemiological data regarding PCR-based clade-associated profiles of C. auris in Türkiye.

Since its initial identification in 2009, Candidozyma auris demonstrates high virulence and multidrug resistance, posing a significant challenge to health management due to its association with nosocomial infections and difficulties in laboratory identification. While Candidozyma auris infections have been reported in Turkey since 2019, data regarding the pediatric population remain exceedingly rare. We present the first two pediatric cases of Candidozyma auris infection at our tertiary care center, with microbiological characteristics and phylogenetic features of the isolates. We documented two cases of a Candidozyma auris infection (urinary tract and bloodstream) in pediatric patients between August 2022 and September 2023. Microbiological features and antifungal susceptibility profiles of the isolates were analyzed. Phylogenetic analysis of the ITS1–5.8S–ITS2 rDNA region was conducted to confirm species‐level identification and evaluate the phylogenetic relationship of the isolates with global reference sequences. The isolates were closely related to Clade I reference sequences and isolates were resistant to amphotericin B but susceptible to fluconazole and echinocandins. This is the first report presenting Candidozyma auris infections in pediatric patients with phylogenetic analysis and underscores the urgent need for heightened vigilance and strict infection control measures.

Background and Objective: Currently, there is a need for alternative antimicrobial and anti-biofilm strategies owing to the combined challenges of multidrug resistance and biofilm formation by Stenotrophomonas maltophilia. Thus, this study aimed to investigate the antibacterial and antibiofilm effects of extracts from Thymus serpyllum, Mentha piperita, Rosmarinus officinalis, Tilia cordata, Salvia officinalis, and Thymbra spicata against S. maltophilia, as well as the interactions of carnosic acid, luteolin, and carnosol compounds in these extracts with potential target molecules. Materials and Methods: Plant extracts were obtained using a Soxhlet device. Antimicrobial activity against 16 clinical S. maltophilia isolates was evaluated using the disk diffusion method, and the antibiofilm effect was assessed using the microtiter plate method. Carnosic acid, luteolin, and carnosol compounds in the extracts were selected as ligands, and a binding analysis was performed with proteins. Results: The T. serpyllum extract showed the highest inhibition zone (20.5 ± 2.8 mm; p < 0.005), with dose-dependent antimicrobial activity (1024 μg/mL > 512 μg/mL; p < 0.05). Among the assessed 15 biofilm-producing strains, T. serpyllum inhibited 10, S. officinalis inhibited six, and R. officinalis inhibited five strains. Molecular docking indicated strong binding energies (carnosic acid: –8.51 kcal/mol, luteolin: –7.62 kcal/mol, carnosol: –9.23 kcal/mol) and multiple interactions with the MlaC protein. Conclusion: These findings suggest that extracts from T. serpyllum, S. officinalis, and R. officinalis may target the Mla pathway and exhibit promising antimicrobial and antibiofilm effects against multidrug-resistant S. maltophilia, likely through the associated active compounds. The molecular docking analyses further supported the potential of these extracts to disrupt membrane integrity by interfering with the Mla system, thereby enhancing bacterial susceptibility to antimicrobial agents. However, additional studies are required to validate these mechanisms and investigate their broader biological implications.

İmmünoloji, vücudumuzdaki bağışıklık olayları ve vücudumuzun çeşitli yabancı maddelere karşı savunma mekanizmalarını, bağışıklık sisteminin yapısını, normal ve normal dışı fonksiyonlarını da inceler. İnsanlar yaşamları boyunca birçok enfeksiyon etkeni ile karşılaşma riskine sahiptirler. İmmün sistemin en önemli işlevi bu enfeksiyonları engellemek ve gelişen enfeksiyonları ortadan kaldırmaktadır. İmmün sistemi doğuştan ya da sonradan bozulmuş hastalarda gördüğümüz ciddi, uzun süren ve ölüme kadar götürebilen enfeksiyonlar immün sistemin vücudumuz için yaşamsal olan fonksiyonlarını anlamamız açısından oldukça önemlidir. İmmün sistemin antijenlere verdiği cevap temel olarak iki mekanizma ile oluşturulur: enfeksiyonlara karşı ilk engeli oluşturan ‘doğal (nativ, innate, özgül olmayan) immünite’ ve bunun sonrasında daha yavaş olarak devreye girerek, daha etkin bir savunma sağlayan ‘edinsel (adaptif, edinsel, özgül) immünite’. Doğal immünitenin mekanizmaları mikroorganizmaların taşıdığı ortak yapıları tanır. Edinsel immünite hücreleri ise mikroorganizmaların ürettiği çok sayıda değişik antijeni tanır. Antijenler tüm bağışıklık sisteminde kilit rol oynamaktadır. Bu bölümde immünolojiye kısa bir giriş yapılarak antijenler ve özelliklerinden bahsedilecektir.

Hepatitis C virus (HCV) is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide. HCV has 8 genotypes (GT) and 86 subtypes and distribution of GTs varies based on geographical regions, transmission routes and even in cultural groups. The determination of viral genotype is crucial in choosing antiviral treatment, determining the duration of therapy, and monitoring treatment respose. Since 2014, with the usage of direct-acting antiviral agents (DAAs) in the treatment of HCV infections, a cure rate over 95% could be possible. Epidemiological data are important to combat a chronic HCV infections. Due to its geographical location, Turkey is like a bridge connecting Asia and Europe. Istanbul is the biggest and most crowded city of Turkey and has received immigration from many different countries, especially from Syria, in recent years and immigration still goes on. In addition, the COVID-19 pandemic has had devastating effects in our country. In this study, we determined the HCV genotypes in Health Sciences University Ümraniye Training and Research Hospital, in Istanbul between 2016 and 2022. Of the 322 patients analyzed during this 7-year period, HCV GT1b was the most prevalent GT in 65.2%, followed by GT3 in 15.5%, GT1a in 10.6%. Our data serve as a great mirror for HCV epidemiology in Turkey and contribute to global data.

Objective: Toxoplasma gondii, rubella, and cytomegalovirus (CMV) are among the TORCH (Toxoplasma, Others, Rubella, Cytomegalovirus, Herpes simplex virus) group microorganisms. Knowing regional epidemiological data on TORCH group infections is important, especially when deciding whether to perform routine screening at the regional and national levels. Our study aimed to evaluate the frequency of T. gondii, rubella, and CMV IgM and/or IgG antibodies in female patients admitted to a state hospital in İstanbul. Method: T. gondii, rubella, and CMV IgG and IgM antibody results tested in patient sera between January 2017 and December 2020 were evaluated retrospectively. Results: The results of 33 636 samples were evaluated. The highest rate of seropositivity was detected in the 20-29 age group (n=4626, 26.72%). The highest of antibody positivity was reported in 2019 (33.29%). The IgG seropositivity rate was 24.1% for T. gondii, 93.5% for rubella, and 98.3% for CMV. Conclusion: Except for the differences in T. gondii seroprevalence, the results of our study seem to be similar to those of other studies both in our country and globally. The seronegativity rate (74.9%) for T. gondii was high in our research, which indicates that pregnant women should be carefully monitored for T. gondii infection in our region. We conclude that more comprehensive studies are needed to establish national screening programs for TORCH group agents. Keywords: CMV, rubella, TORCH, toxoplasma, seropositivity

Objective: We aimed to determine an appropriate anti-HCV test cut-off value for the HCV-RNA study and contribute to the development of correct algorithms by evaluating our hospital’s anti HCV and HCV-RNA test results between 2017-2019. Methods: Available HCV-RNA test results of patients who were found to have reactivity in anti-HCV were analyzed. Patients with anti-HCV reactivity were analyzed by dividing into age groups 0-20 years, 21-40 years, 41-60 years, and ≥61 years. HCV-RNA results were also evaluated within the same age groups. Patients with anti-HCV reactivity were divided into three groups according to their S/Co values as 1-5 mLU/mL, 5.1-10 mLU/mL, and ≥10.1 mLU/mL, and statistical analysis was performed. Results: Anti-HCV reactive results were divided into groups of 1.0-3.8 mLU/mL and ≥3.9 mLU/mL according to S/Co values, and HCV-RNA positivity was 2% and 44.4% respectively. When divided into three groups as 1-5 mLU/mL, 5.1-10 mLU/mL, and ≥10.1 mLU/mL according to S/Co values, the HCV RNA positivity rate was 1.8%, 25%, and 55.2%, respectively. The difference between the groups was statistically significant. Conclusion: Countries should carry out comprehensive studies to represent their populations to determine cut-off values for widely used kits and to make this applicable with algorithms.