Background/Objectives: Escherichia coli is one of the leading causes of surgical site infections (SSIs) and poses a growing public health concern due to its increasing antimicrobial resistance. High rates of extended-spectrum beta-lactamase (ESBL) production among E. coli strains complicate treatment outcomes and emphasize the need for effective surveillance and control strategies. Methods: A total of 691 E. coli isolates from general surgery clinics (2020–2025) were identified using MALDI-TOF MS. Antibiotic susceptibility data and patient variables were cleaned, encoded, and used to predict resistance using the Random Forest, CatBoost, and Naive Bayes algorithms. SMOTE addressed class imbalance, and model performance was assessed through various validation methods. Results: Among the three machine learning models tested, Random Forest (RF) showed the best performance in predicting antibiotic resistance of E. coli, achieving median accuracy, precision, recall, and F1-scores of 0.90 and AUC values up to 0.99 for key antibiotics. CatBoost performed similarly but was less stable with imbalanced data, while Naive Bayes showed lower accuracy. Feature importance analysis highlighted strong inter-antibiotic resistance links, especially among β-lactams, and some influence of demographic factors. Conclusions: This study highlights the potential of simple, high-performing models using structured clinical data to predict antimicrobial resistance, especially in resource-limited clinical settings. By incorporating machine learning into antimicrobial resistance (AMR) surveillance systems, our goal is to support the advancement of rapid diagnostics and targeted antimicrobial stewardship approaches, which are essential in addressing the growing challenge of multidrug resistance.

BACKGROUND: Candida (Candidozyma) auris is a high priority fungal pathogen due to its antifungal resistance and its association with increased morbidity and mortality in infected patients. OBJECTIVES: The aim of this study was to identify Candida species in clinical samples and to determine the clades and in vitro antifungal resistance of C. auris . DESIGN: Retrospective cohort SETTINGS: Single-center tertiary hospital in Türkiye MATERIAL AND METHODS: The study was conducted in the Medical Microbiology Laboratory of Ümraniye Training and Research Hospital between December 2023 and October 2024. Fungal samples were identified using bio-Mérieux VITEK MS v.3.2 (bio-Mérieux, France) and RT-PCR. Antifungal susceptibility testing of C. auris was performed by VITEK 2 Compact AST YS08 and SYO. MAIN OUTCOME MEASURES: Identification of Candida species, in-vitro antifungal resistance of C. auris SAMPLE SIZE: 846 fungal isolates obtained from 746 patients were included. RESULTS: A total of 846 fungal isolates were identified, with C. albicans being the most common (n=440, 52%), followed by Nakaseomyces glabratus (n=124, 14.7%), C. parapsilosis (n=85, 10.1%), C. tropicalis (n=69, 8.2%) and C. auris (n=57, 6.7%). All C. auris isolates were susceptible to anidulafungin. Of these isolates, 47 (82%) were resistant to fluconazole, 34 (60%) to amphotericin B, four (7%) to caspofungin and three (5%) to micafungin. One isolate was resistant to amphotericin B, fluconazole, caspofungin and micafungin. A total of 31 (54%) isolates were resistant to amphotericin B and fluconazole. In accordance with the manufacturer's recommendations, 57 isolates were evaluated as Clade-1. CONCLUSION: C. auris infections are becoming increasingly common. In order to better understand antifungal-resistance of this pathogen, advanced methods should be used for rapid detection of clades and mutations in the FKS gene should be revealed. LIMITATIONS: Single center, whole genome sequence analysis were not performed.

BACKGROUND: The increase in carbapenem-resistant K. pneumoniae (CR-Kp) in intensive care units (ICUs) causes treatment difficulties and increases risk in mortality. OBJECTIVES: The aim of this study was to investigate the susceptibility rates of CR-Kp isolates obtained from ICUs to ceftazidime-avibactam (CAZ-AVI) and colistin, carbapenem resistance genes, clonal relationships and clinical characteristics of the patients. DESIGN: Retrospective cohort SETTING: Single-center, University of Health Sciences, Ümraniye Training and Research Hospital MATERIALS AND METHODS: This study was conducted between June 2023 and December 2024. Isolates were identified using VITEK MS v.3.2, and antibiotic susceptibility testing was performed using the VITEK 2 Compact system. CAZ-AVI susceptibility was determined using disk diffusion, and colistin susceptibility was determined using broth microdilution to determine minimum inhibitory concentration (MIC) values. Carbapenem resistance genes were determined using multiplex real-time polymerase chain reaction (RT-PCR) and clonal relationship arbitrarily primed-polymerase chain reaction (AP-PCR). MAIN OUTCOME MEASURES: Resistance genes of CR-Kp isolates, clonal relationships, CAZ-AVI and colistin resistance, and clinical characteristics of patients SAMPLE SIZE: Ninety-seven isolates from 76 patients RESULTS: Among patients with CR-Kp isolates, central venous catheter use was detected in 59 cases (78%), ventilator-associated pneumonia in 44 cases (58%), and bacteremia in 39 cases (51%), respectively. It was determined that 53 of the patients (70%) died. Using the AP-PCR method, 60 different genotypes were identified among 97 isolates, and clustering was determined in 42 of the isolates (46%). It was determined that 36 (37%) of the isolates were resistant to colistin and 42 (45%) were resistant to CAZ-AVI. NDM+OXA-48, OXA-48, KPC, KPC+NDM, and NDM genes were detected in 40 (43%), 32 (35%), 10 (11%), 2 (2%), and 3 (3%) isolates, respectively. It was determined that 30 (75%) of the isolates with NDM+OXA-48 and only 4 (12%) of the isolates with OXA-48 were resistant to CAZ-AVI. CONCLUSION: In addition to OXA-48, an increase in the frequency of CR-Kp isolates containing the NDM, NDM+OXA-48, KPC+NDM, and OXA-48+KPC genes were also detected. It was also determined that resistance to colistin and CAZ-AVI is increasing. The AP-PCR method can also be used to investigate infections. LIMITATIONS: Single center, Pulsed Field Gel Electrophoresis (PFGE) could not be performed together with AP-PCR

BACKGROUND: Candidozyma auris is resistant to many antifungals, spreads rapidly and causes deaths in patient groups with comorbid factors. OBJECTIVES: The aim of this study was to determine the virulence of C. auris , antifungal resistance genes and clinical characteristics of the patients. DESIGN: Retrospective cohort SETTING: Single-center MATERIAL AND METHODS: This study was conducted between August 2022 and December 2023 at Ümraniye Training and Research Hospital. ITS1-5.8S-ITS2 and ITS1-ITS4 gene regions of the rDNA gene of C. auris isolates identified by VITEK MS v.3.2 were amplified by polymerase chain reaction (PCR) method. These regions were partially sequenced using the Sanger method. The presence of C. auris specific CDR1, ERG11, MDR1, ACT1, SAP5, HYR3, ALS5, IFF4, FUR1, PLB3, PGA26 and PGA52 gene regions were determined by PCR. Antifungal susceptibility testing of C. auris was performed with VITEK 2 Compact AST YS08 and SYO. MAIN OUTCOME MEASURES: Variations in C. auris isolates, antifungal resistance and clinical characteristics of patients SAMPLE SIZE: Forty-four isolates from 31 patients RESULTS: According to gene regions, nine different variations were identified in our hospital, with VAR-1 being the most common. Twenty-five (80.6%) of the patients died and isolation of the causative agent was between days 1–30 in 13 (41.9%) patients. Antibiotic use, ICU admission rate, and central venous catheter use in patients were 29 (93.6%), 28 (90.3%), and 21 (67.7%), respectively. Hypertension, diabetes mellitus (DM) and septic shock were found in 14 (45.2%), 13 (41.9%) and 10 (32.3%) patients, respectively. Antifungal resistance rates of the isolates were determined as 97.7% and 84.1% for amphotericin B and fluconazole, respectively. No resistance to micafungin and caspofungin was detected. The survival rate with echinocandin use was 22% (4 patients). CONCLUSION: Identification of gene regions is valuable in determining the pathogenicity of C. auris . Due to the presence of comorbidities in patients with C. auris , it is not possible to determine the exact proportion of deaths attributable to C. auris alone. LIMITATIONS: Single center setting; gene regions could not be expressed.

Backgrounds/Objectives: This study aimed to quantify biofilm production and characterize the distribution of the biofilm-associated ica genes (icaA, icaD, icaB, icaC, icaR) in coagulase-negative staphylococci (CoNS) isolates, and to assess the association between these genes and antibiotic resistance profiles. Methods: A total of 121 CoNS isolates collected at Ümraniye Training and Research Hospital between 1 January and 30 August 2024 were identified by VITEK 2 Compact and MALDI-TOF MS. Biofilm production was quantified using the microtiter plate assay, and the presence of ica genes was determined by quantitative real-time PCR (qPCR). Antimicrobial susceptibility testing (AST) was performed with the VITEK 2 Compact (bioMérieux), and minimum inhibitory concentrations (MICs) were interpreted according to EUCAST criteria. Results:S. epidermidis was found to have the highest biofilm production capacity among the CoNS isolates, followed by S. haemolyticus. The icaA gene was detected in 99.17% of isolates, followed by icaR (70.24%), icaD (55.37%), and both icaB and icaC (28.92% each). The highest resistance rates were observed for oxacillin (85.8%) and erythromycin (85.1%), while all isolates remained susceptible to linezolid, daptomycin, and vancomycin. Conclusions: The high prevalence of ica genes in CoNS isolates indicates that biofilm formation plays a critical role in the pathogenesis of these species. The findings reveal that CoNS have a strong biofilm production potential, which is a decisive factor in their pathogenicity. However, the high methicillin resistance rates emerge as one of the main factors limiting the effectiveness of current treatment options. Therefore, future studies need to focus on the development of anti-biofilm approaches and alternative therapeutic strategies.

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.