A microbiology laboratory receives a corneal scraping from a patient with keratitis. Microscopic examination with calcofluor white stain reveals the presence of septate hyphae and conidiophores with a foot cell and phialides. The MOST likely genus is:

A clinical microbiology laboratory is performing antimicrobial susceptibility testing using the broth microdilution method. The minimum bactericidal concentration (MBC) is determined by:

A patient with a history of diabetes mellitus develops a severe foot ulcer. Deep tissue cultures grow multiple anaerobic bacteria, including Clostridium perfringens. The MOST concerning virulence factor produced by this organism in this context is:

A patient with HIV infection and a low CD4+ T-cell count presents with fever, weight loss, and cough. Chest X-ray shows diffuse interstitial infiltrates. Sputum induction reveals oval yeast cells with narrow-based budding. The MOST likely diagnosis is:

A patient with a history of chronic obstructive pulmonary disease (COPD) experiences an acute exacerbation.
Sputum culture grows numerous Gram-negative coccobacilli that are oxidase-positive and grow on chocolate agar but not on sheep blood agar. The MOST likely organism is: