Defining the complex role of the microbiome in colorectal cancer and the discovery of novel, protumorigenic microbes are areas of active investigation. In the present study, culturing and reassociation experiments revealed that toxigenic strains of Clostridioides difficile drove the tumorigenic phenotype of a subset of colorectal cancer patient–derived mucosal slurries in germ-free ApcMin/+ mice. Tumorigenesis was dependent on the C. difficile toxin TcdB and was associated with induction of Wnt signaling, reactive oxygen species, and protumorigenic mucosal immune responses marked by the infiltration of activated myeloid cells and IL17-producing lymphoid and innate lymphoid cell subsets. These findings suggest that chronic colonization with toxigenic C. difficile is a potential driver of colorectal cancer in patients. Significance: Colorectal cancer is a leading cause of cancer and cancer-related deaths worldwide, with a multifactorial etiology that likely includes procarcinogenic bacteria. Using human colon cancer specimens, culturing, and murine models, we demonstrate that chronic infection with the enteric pathogen C. difficile is a previously unrecognized contributor to colonic tumorigenesis. See related commentary by Jain and Dudeja, p. 1838. This article is highlighted in the In This Issue feature, p. 1825

Using next-generation sequencing (NGS), we developed and validated a whole-genome sequencing (WGS)-based clinical test for fungal species identification on clinical isolates. The identification is mainly based on the fungal ribosomal internal transcribed spacer (ITS) region as the primary marker, and additional marker and genomic analysis applied for species within the Mucorales family (using the 28S rRNA gene) and Aspergillus genus (using the beta-tubulin gene and k-mer tree-based phylogenetic clustering). The validation study involving 74 unique fungal isolates (22 yeasts, 51 molds, and 1 mushroom-forming fungus) showed high accuracy, with 100% (74/74) concordance on the genus-level identifications and 89.2% (66/74) concordance on the species level. The 8 discrepant results were due to either the limitation of conventional morphology-based methodology or taxonomic changes. After one year of implementation in our clinical laboratory, this fungal NGS test was utilized in 29 cases; the majority of them were transplant and cancer patients. We demonstrated the utility of this test by detailing five case studies, in which accurate fungal species identification led to correct diagnosis, treatment adjustment or was ruled out for hospital acquired infection. This study provides a model for validation and implementation of WGS for fungal identification in a complex health system that serves a large immunocompromised patient population.

A 39-year-old man presented with a history of fatigue, malaise, and rash with varied morphology on his perianal region. Polymerase chain reaction testing of the lesions confirmed coinfection with monkeypox and herpes simplex virus type 2. We emphasize the difficulty in distinguishing between monkeypox virus and herpes simplex virus type 2 based on history and examination alone.

Bacterial commensals of the human genitourinary tract, Mycoplasma hominis and Ureaplasma species (parvum and urealyticum) can be sexually transmitted, with the potential to cause nongonococcal urethritis, pelvic inflammatory disease, and infertility. Mycoplasma hominis and Ureaplasma species may also cause severe invasive infections in immunocompromised patients. Current culture-based methods for Mycoplasma/Ureaplasma identification are costly and laborious, with a turnaround time between 1 and 2 weeks. We developed a high-throughput, real-time multiplex PCR assay for the rapid detection of M. hominis and Ureaplasma species in urine, genital swab, body fluid, and tissue. In total, 282 specimens were tested by PCR and compared with historic culture results; a molecular reference method was used to moderate discrepancies. Overall result agreement was 99% for M. hominis (97% positive percentage agreement and 100% negative percentage agreement) and 96% for Ureaplasma species (96% positive percentage agreement and 97% negative percentage agreement). Specimen stability was validated for up to 7 days at room temperature. This multiplex molecular assay was designed for implementation in a high-complexity clinical microbiology laboratory. With this method, >90 samples can be tested in one run, with a turnaround time of 4 to 5 hours from specimen extraction to reporting of results. This PCR test is also more labor effective and cost-effective than the conventional culture-based test, thus improving laboratory efficiency and alleviating strains because of labor shortages.

Background: Urinary tract infections are prone to overdiagnosis, and reflex urine culture protocols offer a valuable opportunity for diagnostic stewardship in this arena. However, there is no recommended standard testing approach. Patients with cancer are often excluded from reflex urine culture protocols, especially if they are severely immunosuppressed or neutropenic. The aim of this study was to evaluate the performance characteristics of urine screening studies, including dipstick urinalysis for nitrite and leukocyte esterase and urine microscopy for white blood cell count, to detect significant pathogen growth. Methods: A retrospective study of 58 098 urine cultures with a paired dipstick urinalysis with or without urine microscopy was performed at Memorial Sloan Kettering Cancer Center in New York City, evaluating data from 1 January 2018 to 31 December 2020. A dipstick urinalysis was considered negative only if leukocyte esterase and nitrite were undetected. Results: A negative dipstick urinalysis had a negative predictive value of 98% for clinically significant bacteriuria in voided urine and 95% for catheterized urine. Notably, a negative urine dipstick test screen maintained a high negative predictive value among patients with neutropenia and in those with antibiotic exposure before testing. Finally, the presence of pyuria ≥10 white blood cells per high-power field on urine microscopy offered negligible incremental diagnostic benefit in samples with a negative dipstick urinalysis. Conclusions: Reflex urine culture protocols contingent upon a screening dipstick urinalysis are a safe and effective platform for diagnostic stewardship in patients with cancer including those with neutropenia.