Humoral immunodeficiency is suspected in a patient and he is under investigation. Which of the following infections would not be consistent with the diagnosis?
Giardiasis
Pneumocystis carinii pneumonia
Recurrent sinusitis
Recurrent subcutaneous abscesses
Answer is B (Pneumocystis carinii pneumonia) : Pneumocystis carinii infections are associated with deficient cell mediated immunity and not with humoral immunodeficiency. Humoral immunodeficiencies i.e. predominantly antibody deficiencies are associated with recurrent serious infections with pyogenic bacteria and giardiasis. Recurrent sinusitis and recurrent subcutaneous abscess result from infection with pyogenic bacteria and hence are consistent with diagnosis of humoral immunodeficiency.