Question

A 35-year-old man has a painful skin abscess. Some of the purulent fluid drained is sent to the lab for identification of the organism. Rapid identification of these organisms is done by evaluation of the clumping of coated latex beads. With what must the beads have been coated?

Properdin and platelet factor 3
Interleukin-1 (IL-1) and factor VIII (antihemophilic factor)
Prothrombin and C3b
Transferrin and plasminogen
IgG and fibrinogen

Answer 1

The coated latex beads must be covered with IgG and fibrinogen to rapidly identify organisms such as Staphylococcus aureus through the agglutination assay.

Step-by-step explanation:

Rapid identification of certain pathogenic organisms, such as Staphylococcus aureus, in a clinical setting can be accomplished through the use of agglutination assays.

One such method is the indirect agglutination assay using latex beads. When purulent fluid from an abscess is tested, and the latex beads used in the assay are coated with IgG and fibrinogen, this indicates the presence of organisms capable of clumping factor and protein A, typically associated with S. aureus.

In the presence of coagulase-positive staphylococci, such as S. aureus, the coated beads will rapidly clump together, forming visible aggregates.

The reason why the beads must be coated with IgG and fibrinogen is due to S. aureus's production of clumping factor and protein A—a result of their ability to exploit the normal blood clotting mechanism to protect themselves from the immune system.

Latex beads coated with IgG and fibrinogen interact with the bacteria's clumping factor and protein A, leading to the agglutination that signifies a positive identification of the bacteria.

Answer 2

The beads must have been coated with IgG and fibrinogen for the rapid identification of organisms through the evaluation of clumping.

Step-by-step explanation:

The use of coated latex beads in the identification of organisms through clumping is a technique known as latex agglutination. In this case, the appropriate coating for the latex beads is IgG and fibrinogen. IgG (Immunoglobulin G) is an antibody that plays a crucial role in the immune response by binding to pathogens, while fibrinogen is a plasma protein involved in blood clotting. Coating the beads with IgG and fibrinogen allows for the detection of specific antigens on the surface of the organisms, leading to the clumping (agglutination) of the latex beads.

The other options provided (Properdin and platelet factor 3, Interleukin-1 and factor VIII, Prothrombin and C3b, Transferrin and plasminogen) do not align with the typical components used for latex agglutination in the identification of organisms.

In summary, the choice of IgG and fibrinogen as coating agents for the latex beads is logical in the context of identifying organisms in a skin abscess. This method provides a rapid and specific means of detecting the presence of pathogens in the purulent fluid drained from the abscess, aiding in the timely diagnosis and treatment of the infection.