Genome-wide analysis of in vivo-evolved Candida auris reveals multidrug-resistance mechanisms.

Candida auris, an emerging and multidrug-resistant fungal pathogen, has led to numerous outbreaks in China. While the resistance mechanisms against azole and amphotericin B have been studied, the development of drug resistance in this pathogen remains poorly understood, particularly in in vivo-generated drug-resistant strains. This study employed pathogen whole-genome sequencing to investigate the epidemiology and drug-resistance mutations of C. auris using 16 strains isolated from two patients. Identification was conducted through Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibilities were assessed using broth microdilution and Sensititre YeastOne YO10. Whole-genome sequencing revealed that all isolates belonged to the South Asian lineage, displaying genetic heterogeneity. Despite low genetic variability among patient isolates, notable mutations were identified, including Y132F in ERG11 and A585S in TAC1b, likely linked to increased fluconazole resistance. Strains from patient B also carried F214L in TAC1b, resulting in a consistent voriconazole minimum inhibitory concentration of 4 µg/mL across all isolates. Furthermore, a novel frameshift mutation in the SNG1 gene was observed in amphotericin B-resistant isolates compared to susceptible ones. Our findings suggest the potential transmission of C. auris and emphasize the need to explore variations related to antifungal resistance. This involves analyzing genomic mutations and karyotypes, especially in vivo, to compare sensitive and resistant strains. Further monitoring and validation efforts are crucial for a comprehensive understanding of the mechanisms of drug resistance in C. auris.

Causative Microorganisms Isolated from Patients with Intra-Abdominal Infections and Their Drug Resistance Profiles: An 11-Year (2011-2021) Single-Center Retrospective Study.

Objective: To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections (IAIs). Methods: A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021. Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the VITEK 2 compact system and the Kirby-Bauer method. AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute. Results: Of the 2,926 strains identified, 49.2%, 40.8%, and 9.5% were gram-negative bacteria, gram-positive bacteria, and fungi, respectively. Escherichia coli was the most prevalent pathogen in intensive care unit (ICU) and non-ICU patients; however, a significant decrease was observed in the isolation of E. coli between 2011 and 2021. Specifically, significant decreases were observed between 2011 and 2021 in the levels of extended-spectrum ß-lactamase (ESBL)-producing E. coli (from 76.9% to 14.3%) and Klebsiella pneumoniae (from 45.8% to 4.8%). Polymicrobial infections, particularly those involving co-infection with gram-positive and gram-negative bacteria, were commonly observed in IAI patients. Moreover, Candida albicans was more commonly isolated from hospital-associated IAI samples, while Staphylococcus epidermidis had a higher ratio in community-associated IAIs. Additionally, AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers, while the overall resistance rates (56.9%-76.8%) of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria. Indeed, Enterococcus faecium, Enterococcus faecalis, S. epidermidis, and S. aureus were consistently found to be susceptible to vancomycin, teicoplanin, and linezolid. Similarly, C. albicans exhibited high susceptibility to all the tested antifungal drugs. Conclusion: The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAIs were altered between 2011 and 2021. This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections.

Analysis of 50 cases of bloodstream infection with Listeria monocytogenes / 中国热带医学

@#Abstract: Objective　To analyze the characteristics of bloodstream infection of Listeria monocytogenes and provide basis for the diagnosis and treatment of the disease. Methods　We retrospectively analyzed the cases of Listeria monomyrhosi bloodstream infection in Peking Union Medical College Hospital (PUMCH) from April 2012 to April 2022. The age, sex, onset time, underlying disease, symptoms, diagnosis, treatment and prognosis of the patients were analyzed, as well as the changes of white blood cells (WBC), neutrophils, lymphocytes, and C-reactive protein (CRP) before and after anti-infection treatment. Results　Fifty cases of Listeria monocytogenes bloodstream infection confirmed by blood culture were involved. The age of patients ranged from 0 to 82 (43.7±20.0) years old, among whom 20.0% were over 60 years old. The onset time of patients was the highest in spring (44.0%), followed by winter (24.0%), and relatively fewer in summer and autumn (14.0%-18.0%). The median diagnosis time was 3 days (1-60 days). After the etiological diagnosis, 45 patients (90.0%) had underlying diseases or pregnancy status, and 45 patients were adjusted to the target antibacterial treatment mainly with carbapenems (48.9%) and penicillins (44.4%). The level of WBC, neutrophils, lymphocytes, monocytes, and CRP after treatment were significantly lower than those pre-treatments (P<0.05). Among all patients, 36 cases (72.0%) were treated according to the Antimicrobial Treatment Guidelines for Fever Sanford, of which 26 cases (72.2%) were discharged from the hospital, two cases died, one case was transferred to other hospitals, and 7 cases had a poor prognosis. Conclusions　Autoimmune diseases, tumor diseases, pregnant patients are susceptible to Listeria monocytogenes infection. Penicillins are the first choice for effective empiric therapy. For the patients allergic to penicillins, trimethoprim/sulfamethoxazole or meropenem could be used.