SHM Converge Scientific Abstract ePoster Gallery-When Negative Tests Mislead: Mycoplasma Pneumonia Uncovered Through Cold Agglutinin Hemolysis

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This case report describes a 28-year-old man with fever, cough, worsening shortness of breath, and hypoxemia whose chest CT showed multifocal ground-glass opacities. He was treated for community-acquired pneumonia with ceftriaxone and azithromycin, but initial atypical infectious testing was negative, so azithromycin was stopped. His condition then deteriorated, requiring intubation.<br /><br />On hospital day 7, he developed a sudden hemoglobin drop, elevated LDH, red blood cell agglutination with spherocytes on smear, a positive direct antiglobulin test, low C3, and a high cold agglutinin titer, all suggesting cold agglutinin hemolytic anemia (CAHA). Although early microbiologic tests had been negative, bronchoalveolar lavage later returned positive for Mycoplasma pneumoniae. Treatment was changed by stopping ceftriaxone and restarting doxycycline, after which he rapidly improved, defervesced, and was successfully extubated.<br /><br />The report emphasizes that Mycoplasma pneumoniae can cause extrapulmonary complications such as CAHA, which may worsen hypoxia and mimic progression of pneumonia. It also highlights that respiratory pathogen testing, while generally highly sensitive, can be falsely negative early in infection. In patients with pneumonia plus unexplained anemia or hemolysis, elevated cold agglutinin titers should prompt renewed suspicion for Mycoplasma pneumoniae, even when initial testing and imaging are not classic.

Asset Subtitle

Gauri Pikale

Meta Tag

Author List Ahmad Abdelkhalek, Angeliqua Grange, Gauri Pikale, Joaquim Noguer, Maryana Yaremko, Oishi Barua, Prashant Sura, Preksha Shah

Category Clinical Vignettes

Concept Cold Agglutinin Disease

Concept Mycoplasma pneumoniae

Concept Hemolytic Anemia

Concept Pleural Fluid Lactate Dehydrogenase

Concept Red Blood Cell Agglutination

Distinguished Non-Finalist

Presenter Organization Northwestern Medicine McHenry Hospital/Rosalind Franklin University of Medicine and Science

Presenting Author Gauri Pikale

Track Adult

Keywords

Mycoplasma pneumoniae

cold agglutinin hemolytic anemia

community-acquired pneumonia

ground-glass opacities

hypoxemia

hemolysis

direct antiglobulin test

bronchoalveolar lavage

doxycycline

respiratory pathogen testing

Cold Agglutinin Disease

Mycoplasma pneumoniae

Hemolytic Anemia

Pleural Fluid Lactate Dehydrogenase

Red Blood Cell Agglutination