CLS CLS Clinical Microbiology and Immunology 2

Question 1

Which antibody class is the FIRST produced during a primary immune response?

Accepted Answer

IgM

Answer

IgM is the first antibody class produced during a primary immune response; its pentameric structure makes it highly effective at agglutination and complement activation.

Question 2

Beta-lactamase-producing organisms are resistant to which antibiotic class?

Accepted Answer

Beta-lactams (penicillins/cephalosporins)

Answer

Beta-lactamase enzymes cleave the beta-lactam ring of penicillins and cephalosporins, inactivating the antibiotic before it can inhibit cell wall synthesis.

Question 3

Which test is used as the CONFIRMATORY test for HIV after a positive 4th-generation ELISA/immunoassay screen?

Accepted Answer

Western blot / HIV-1/2 differentiation immunoassay

Answer

An HIV-1/2 differentiation immunoassay (formerly Western blot) confirms HIV infection by detecting antibodies to specific HIV proteins after a reactive screen.

Question 4

The Quellung (capsular swelling) reaction uses type-specific antisera to identify which encapsulated organism?

Accepted Answer

Streptococcus pneumoniae

Answer

The Quellung reaction detects the polysaccharide capsule of Streptococcus pneumoniae; antibody binding causes the capsule to appear swollen and refractile under microscopy.

Question 5

Which type of hypersensitivity reaction is IgE-mediated and involves mast cell degranulation with histamine release?

Accepted Answer

Type I (immediate/anaphylactic)

Answer

Type I hypersensitivity is IgE-mediated; allergen cross-links IgE molecules on mast cells, triggering degranulation and release of histamine and other mediators.

CLS - Certified Laboratory Professional Practice Test

CLS - Certified Laboratory Professional Practice Test

CLS CLS Clinical Microbiology and Immunology 2