A clinical microbiology laboratory is implementing a new multiplex nucleic acid amplification test (NAAT) for the detection of respiratory viral pathogens. To ensure the quantitative accuracy of the assay, it is essential to include:

Which biosafety level (BSL) is required for clinical laboratory work involving the propagation (culture) of Coccidioides immitis/posadasii? 

A microbiology laboratory is processing a stool sample for ova and parasites. A large (approximately 100 µm), thick-shelled, oval egg with a flattened side is observed. This egg MOST likely belongs to:

A Gram-positive rod is isolated from the blood culture of a neonate with sepsis. The organism exhibits weak beta-hemolysis on sheep blood agar, is catalase-positive, hydrolyzes esculin in the presence of bile, and demonstrates characteristic "tumbling" motility in a wet mount prepared from a broth culture incubated at 25° C. Which organism is most likely? 

A clinical microbiology laboratory is using flow cytometry to analyze lymphocyte subsets in a patient with suspected immunodeficiency. Which of the following cell surface markers is typically used to identify helper T cells?