The residency program of infectious diseases and clinical microbiology (IDCM) in Türkiye was started in 1983 by adopting the name IDCM. The IDCM program in Türkiye is a five-year program, including related clinical rotations. Presenting a thesis at the end of this program is mandatory. The first specialty thesis in the field of IDCM was

Clostridioides difficile-associated pseudomembranous colitis (PMC) is a life-threatening inflammatory bowel disease. Here, we aimed to present a 40-year-old woman at 25 weeks of gestation whose pregnancy was terminated earlier than expected. Unfortunately, despite fidaxomicin and oral vancomycin, the patient’s diarrhea did not improve, and she had to undergo a subtotal colectomy. C. difficile infections developing in pregnant women can be catastrophic for both baby and maternal health. Also, antibiotic stewardship is crucial in the prevention of PMC. Therefore, unnecessary and prolonged use of antibiotics should be avoided. Keywords: Clostridioides difficile, pregnant, colectomy, colitis

Pneumocystis jirovecii is a major cause of morbidity and mortality in HIV. It also poses a significant risk to non-HIV immunocompromised patients, especially those with cancer or recent chemotherapy. We evaluated risk factors, diagnostic markers-including lactate dehydrogenase (LDH)-and mortality predictors in PCR-confirmed pneumocystis pneumonia (PJP). We retrospectively analyzed patients with hypoxemia, pulmonary involvement and/or fever who underwent PJP PCR testing at Koç University Hospital between January 2020 and November 2023. Cases were defined as patients with a positive PCR result who fulfilled the EORTC/MSGERC criteria for PJP, whereas the non-PJP group included PCR-negative patients and PCR-positive patients without clinically compatible disease. Clinical, laboratory, and radiologic data-including LDH, fungal load, co-infections, and 4-week mortality-were collected. Of 235 patients, 59 had PCR-confirmed PJP. PJP patients were older (median 70 vs. 64.5, p < 0.001), more often had solid organ malignancies (67.8% vs. 41.5%, p < 0.001), recent chemotherapy (66.1% vs. 41.5%, p = 0.001), and higher fungal loads (median 10,892 vs. 0, p < 0.001). Bilateral lung lesions (81% vs. 66.5%, p = 0.037) and ground-glass opacities (82.8% vs. 67.7%, p = 0.041) were more frequent. Serum LDH increased by 81.6% in PJP vs. 20.7% in controls (p = 0.001), whereas no significant difference was observed among patients with elevated baseline LDH (29.7% vs. 16.3%, p = 0.397). Multivariate analysis identified older age (OR 1.042, p = 0.017), solid organ malignancy (OR 2.304, p = 0.048), and CMV co-infection (OR 3.786, p = 0.006) as independent factors associated with PJP, whereas ICU admission at diagnosis was inversely associated with PJP (OR 0.239, p = 0.005). The 4-week mortality was 37%, with bacterial co-infection as the strongest predictor (OR 5.854, p = 0.009). Older age, solid organ malignancy, and CMV co-infection increased PJP risk, while bacterial co-infection predicted mortality. LDH changes supported diagnosis, but not when baseline levels were already elevated, in this predominantly oncology cohort.

Background: Infectious complications remain a leading cause of mortality after hematopoietic stem cell transplantation (HSCT). We aimed to describe post-HSCT infections and their impact on survival in a center from a region with high antimicrobial resistance. Methods: We included 522 patients with hematological malignancies undergoing HSCT at Koç University Hospital between 2016 and 2024. Bloodstream and opportunistic infections within 100 days were analyzed. Infection-related mortality (IRM) was defined as death primarily attributable to infectious complications. Predictors of 30- and 100-day mortality were assessed using multivariate logistic regression, including demographic and hematologic features, bloodstream infections (BSIs), invasive aspergillosis (IA), and cytomegalovirus reactivation. Results: The most frequent diagnoses were non-Hodgkin lymphoma (36%), multiple myeloma (33%), and Hodgkin lymphoma (11%). Gram-negative bacteria (GNB) accounted for 73% of BSIs; Escherichia coli (31%) and Klebsiella pneumoniae (30%) were most frequent. Carbapenem resistance was highest in Klebsiella pneumoniae (67%), mainly due to OXA-48 carbapenemase (43%). Carbapenem-resistant Klebsiella pneumoniae (CRKP) bacteremia was associated with significantly reduced 100-day survival (log-rank p < 0.001). IA also significantly impaired survival in the overall cohort (log-rank p < 0.001). In the allogeneic subgroup ( n = 139), 100-day mortality reached 27%, with IA occurring in 19% and CRKP bacteremia in 17%. At 30 days, 25 patients (5%) had died; 24 of these deaths (96%) were attributed to infections. By day 100, 52 patients (10%) had died, and infections accounted for 42 deaths (80%). Conclusion: In a high antimicrobial resistance setting, CRKP bacteremia and invasive aspergillosis were major determinants of early post-HSCT mortality. These findings highlight the need for optimized empirical therapy, antimicrobial stewardship, and strengthened infection prevention strategies in this vulnerable population.

Aim: Antibiotic de-escalation (ADE) is essential, but appears to be underperformed although being possible, which we refer to as a ‘missed opportunity’. We aimed to analyze the ADE missed opportunities in Gram-negative bloodstream infections (BSIs) in a setting with a high antimicrobial resistance profile. Methods: A retrospective, two-centered cohort study was performed from 1 January 2018 to 30 June 2019, including adults with mono- or polymicrobial Gram-negative BSIs. All ADE episodes and 30-day mortality were noted. Results/Discussion: Out of 273 BSIs (43 ADE vs. 230 no-ADE episodes), 101 were considered a ‘missed’ opportunity of ADE (36.9%, 101/273). In multivariate analysis, ADE opportunities were missed 4.4 times more (OR = 4.4; 95% CI 1.24–15.9) in the presence of hematological malignancy and 6.2 times more (OR = 6.2; 95% CI 1.76–22.2) in ESBL. Contrary to this, ADE opportunities were missed 0.24 times less (OR = 0.24; 95% CI 0.09–0.61) among patients with E. coli BSIs, and 0.17 less (OR = 0.17; 95% CI 0.05–0.67) if ertapenem was used as an empirical agent. The ADE missed opportunity group had a higher mortality rate, which is statistically significant in univariate analysis, but not in multivariate analysis. Conclusion: The presence of ESBL and hematological malignancy were the significant barriers to appropriate ADE practice in our study. A good stewardship program must address physician hesitation in ADE practice.