A microbiology laboratory receives a CSF sample from a patient with suspected fungal meningitis. India ink staining reveals encapsulated yeast cells. Culture on Sabouraud dextrose agar grows creamy white colonies. The MOST likely organism is:
A microbiology laboratory is performing antimicrobial susceptibility testing using the Kirby-Bauer disk diffusion method. A bacterial isolate shows no zone of inhibition around a specific antibiotic disk. This result could be due to:
Which virus is recognized as the leading cause of sporadic, severe gastroenteritis in infants and young children globally, for which effective vaccines are now available?
A clinical microbiology laboratory is performing Gram staining on a sputum sample. After adding the crystal violet stain, a delay in the washing step with decolorizer (alcohol-acetone) would MOST likely result in:
A patient presents with a chronic, non-healing skin ulcer in a tropical region. Microscopic examination of a biopsy reveals amastigotes within macrophages. Culture of the biopsy on Novy-MacNeal-Nicolle (NNN) medium yields flagellated promastigotes. The MOST likely diagnosis is cutaneous leishmaniasis caused by:
A patient with a history of valvular heart disease undergoes a dental procedure and subsequently develops a bloodstream infection with Streptococcus mutans. This organism gains access to the bloodstream primarily due to:
A patient with a history of recurrent Clostridioides difficile infection (CDI) is being considered for fecal microbiota transplantation (FMT). Pre-FMT screening of the donor stool sample should include comprehensive testing to exclude potential transmission of enteric pathogens. Which of the following would be the MOST critical to rule out in the donor stool?
During a primary infection with Epstein-Barr virus (EBV), the virus establishes latency in B lymphocytes. The transition from lytic to latent infection is tightly regulated by viral gene expression. Which of the following viral proteins is crucial for the establishment and maintenance of EBV latency and is a key target in EBV-associated lymphomas?
A clinical microbiology laboratory is performing quality control on Gram stain reagents. A control slide containing Escherichia coli and Staphylococcus aureus shows both organisms staining purple after the complete staining procedure. The MOST likely cause of this error is:
A clinical microbiology laboratory encounters a Gram-negative bacillus isolated from a bloodstream infection. The isolate exhibits resistance to multiple antibiotics, including carbapenems. Further phenotypic testing reveals the production of a metallo-beta-lactamase (MBL). Which of the following antibiotic combinations might still retain activity against this isolate?
