Cold agglutinins may develop after an infection induced by which of the following organisms?

Cold agglutinins are antibodies, specifically IgM antibodies, that agglutinate red blood cells at lower temperatures, typically around 4°C. Mycoplasma pneumoniae is known to elicit the production of these cold agglutinins, particularly in cases of atypical pneumonia. The mechanism is thought to involve the organism's surface antigens, which resemble those on red blood cells. This cross-reactivity prompts the immune system to produce antibodies that can agglutinate the red blood cells when the blood is cooled, leading to a characteristic hemolytic anemia in some patients.

In contrast, the other organisms listed are not typically associated with the production of cold agglutinins. Streptococcus pneumoniae is a common cause of bacterial pneumonia but is not primarily linked to cold agglutinin formation. Neisseria gonorrhoeae is associated with gonorrhea and does not provoke this immune response. Salmonella typhi is responsible for typhoid fever and does not lead to the development of cold agglutinins either. Understanding the connection between Mycoplasma pneumoniae and cold agglutinins helps reinforce the unique immunological responses associated with different pathogens.