A 2-year-old boy is brought to the clinic due to a "painful swelling" on his right arm. Medical history includes 2 previous skin infections. The patient had a perianal abscess incised and drained at age 2 months after no improvement following a course of oral antibiotics; cultures grew Staphylococcus aureus. At age 7 months, he had an episode of left inguinal lymphadenitis. Temperature is 37.3 C (99.1 F). Physical examination shows an indurated, fluctuant mass on the lateral aspect of the patient's right arm. The remainder of the physical examination is unremarkable. The mass is drained, and the cultures grow Serratia marcescens; the patient is appropriately treated. Additional laboratory studies show normal leukocyte, platelet, and B- and T-cell concentrations. Dihydrorhodamine flow cytometry is abnormal. In addition to trimethoprim-sulfamethoxazole, which of the following additional prophylactic therapies is recommended in this patient?

Question

A 2-year-old boy is brought to the clinic due to a "painful swelling" on his right arm.  Medical history includes 2 previous skin infections.  The patient had a perianal abscess incised and drained at age 2 months after no improvement following a course of oral antibiotics; cultures grew Staphylococcus aureus.  At age 7 months, he had an episode of left inguinal lymphadenitis.  Temperature is 37.3 C (99.1 F).  Physical examination shows an indurated, fluctuant mass on the lateral aspect of the patient's right arm.  The remainder of the physical examination is unremarkable.  The mass is drained, and the cultures grow Serratia marcescens; the patient is appropriately treated.  Additional laboratory studies show normal leukocyte, platelet, and B- and T-cell concentrations.  Dihydrorhodamine flow cytometry is abnormal.  In addition to trimethoprim-sulfamethoxazole, which of the following additional prophylactic therapies is recommended in this patient?

Quizplus · Accepted Answer

11ec25c8_d621_f85a_bc81_8de089b32db2_MD0003_00 This patient with recurrent skin abscesses has an abnormal dihydrorhodamine (DHR) test consistent with chronic granulomatous disease (CGD). CGD is caused by a gene defect in the NADPH oxidase enzyme complex, which results in an inability to form superoxide radicals and impaired intracellular killing in phagocytes. Patients with CGD classically have recurrent, severe cutaneous and pulmonary infections with catalase-positive bacterial and fungal organisms (eg, Staphylococcus aureus, Serratia, Aspergillus). Other common infections include suppurative adenitis and osteomyelitis. Platelet and B- and T-cell concentrations are normal in CGD; leukocyte count may be normal or elevated (eg, during acute infection). Initial evaluation of patients with suspected CGD includes oxidative burst testing such as DHR flow cytometry or nitroblue tetrazolium. DHR is usually taken up by phagocytes and fluoresces green when oxidized (via NADPH oxidase) to rhodamine; negative fluorescence after stimulation is consistent with CGD, and the diagnosis is confirmed by gene testing. Patients with CGD should receive antibiotic prophylaxis with trimethoprim-sulfamethoxazole and antifungal prophylaxis with itraconazole. Severe phenotypes also benefit from immunomodulation with interferon gamma injections. (Choice A) Live bacterial vaccines such as the bacillus Calmette-Guérin vaccine should be avoided in CGD because they can induce severe infection. Live viral vaccines, as well as inactivated vaccines, are safe because patients with CGD do not have a defective immune response to viruses. (Choice B) Granulocyte colony-stimulating factor is used to increase neutrophil counts in patients with a low absolute neutrophil count (eg, chemotherapy-induced neutropenia, cyclic neutropenia). Neutrophil counts are typically normal in CGD. (Choice C) Intravenous immunoglobulin repletes immunoglobulins in patients with low levels (eg, X-linked agammaglobulinemia), a finding that is not present in CGD. Moreover, patients with low immunoglobulin levels typically have recurrent sinopulmonary, not cutaneous, infections. (Choice E) Valacyclovir is an antiviral drug used as prophylaxis against certain viruses (eg, herpes simplex virus, cytomegalovirus) in some immunocompromised patients with T-cell defects (eg, severe combined immunodeficiency). In contrast, T cells are normal in CGD, and antiviral prophylaxis is not indicated. Educational objective: Chronic granulomatous disease presents with recurrent cutaneous and pulmonary infections with catalase-positive organisms (eg, Staphylococcus aureus, Serratia). Abnormal oxidative burst (eg, dihydrorhodamine testing) is consistent with the diagnosis, and antimicrobial prophylaxis with trimethoprim-sulfamethoxazole and itraconazole is required. References: Chronic granulomatous disease: clinical, molecular, and therapeutic aspects. (http://www.ncbi.nlm.nih.gov/pubmed/26680691)

A 2-Year-Old Boy Is Brought to the Clinic Due to a "Painful