The Shield Down the Drain
Clinical Vignette
A 58-year-old man with biopsy-proven membranous nephropathy is managed in the nephrology clinic for a persistently nephrotic state. Despite treatment with tacrolimus and prednisone, his most recent studies show proteinuria of 8.5 g/day, serum albumin 1.9 g/dL, total cholesterol 324 mg/dL, and serum IgG 312 mg/dL (reference 700–1600). He has 2+ lower-extremity edema but has otherwise been stable.
He presents to the emergency department after two days of fever to 39.1 °C, rigors, purulent cough, right-sided pleuritic chest pain, and progressive dyspnea. On examination his respiratory rate is 26/min, oxygen saturation 90% on room air, and he has focal crackles over the right lower lobe. The white blood cell count is 14.8 x 103/µL with a left shift. Chest radiography reveals a dense right lower lobe consolidation, and blood cultures are obtained before antibiotics are administered.
Within twenty-four hours the blood culture bottles flag positive, and the Gram stain is shown below.
Gram stain prepared from the positive blood culture bottle.
Question 1
Which organism is most likely responsible for this patient's pneumonia and bacteremia?
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Question 2
Which mechanism best accounts for this patient's increased susceptibility to this organism?
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Question 3
After appropriate empiric and definitive antibiotics, which measure is most important for reducing the risk of recurrent invasive pneumococcal disease in this patient?
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References
Ponticelli C, Moroni G. Nephrotic syndrome: pathophysiology and consequences. Journal of Nephrology. 2023;36(8):2179-2190.
Ogi M, Yokoyama H, Tomosugi N, et al. Risk factors for infection and immunoglobulin replacement therapy in adult nephrotic syndrome. American Journal of Kidney Diseases. 1994;24(3):427-436.
Kidney Disease: Improving Global Outcomes (KDIGO) Glomerular Diseases Work Group. KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases. Kidney International. 2021;100(4S):S1-S276.
Kobayashi M, Pilishvili T, Farrar JL, et al. Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023. MMWR Recommendations and Reports. 2023;72(3):1-39.