Case Study

COVID-19 Positive Rule-out Bacterial Pneumonia

Critical Care Medicine Physician, New York, USA

Age, sex:

68-year-old male

Chief complaint:

Feeling unwell with cough and fatigue for one week. SARS-CoV-2 testing was positive.

Significant medical history:

Refractory diffuse large B-cell lymphoma, hypogammaglobulinemia, and recent treatment with Rituximab. Most recently developed progression on Rituximab-Gemcitabine- Oxaliplatin (R-GemOx) chemotherapy. He was in the process of CAR-T cell collection when a household member, developed COVID-19.

Physical exam:

Frail looking with increased work of breathing and poor air entry at the lung bases.

Admission labs:

Chest x-ray showed increased right greater than left patchy airspace opacities. Blood cultures sent, absolute lymphocyte count (ALC) < 1 109/L, absolute neutrophil count (ANC) 5.8 109/L, ferritin 2554 ng/mL, D-dimer 0.68 mg/L, c-reactive protein (CRP) 17.5 mg/L, PCT = 0.10 μg/L.

Admitting diagnosis:


Treatment, interventions:

Initially high flow nasal oxygen 40% FiO2, steroids, remdesivir, convalescent plasma as adjunctive therapy. Intubation and mechanical ventilation was required within 48 hours of hospital admission and was admitted to the ICU where he was proned for 16 hours a day over a 72-hour period with significant improvement in oxygen requirement, radiologic imaging, and laboratory parameters. Serial PCT levels remained below 0.1 ng/mL with negative blood cultures and antibacterial agents were discontinued. The patient steadily improved and was weaned from the ventilator over the ensuing seven days and transferred to the ward.

Key takeaways


Bacterial co-infection and secondary bacterial infections are relatively infrequent
(< 10%) in hospitalized patients with COVID-19, yet over 70% of patients receive antibiotics on hospital admission and often for several days.1 Majority of these patients may not require empiric IV antibiotics. Procalcitonin has a high negative-predictive value at ≤ 0.25 μg/L for determining need for antibiotics in patients with community-acquired pneumonia, including those who have underlying malignancy. PCT levels also have a high negative predictive value when compared to blood cultures.2,3 Serial PCTs can assist with confirming the initial negative result and indicate that antibiotics are no longer necessary.


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  1. Langford BJ, So M, Raybardhan S, Leung V, Westwood D, MacFadden DR, Soucy JR, Daneman N. Bacterial co-infection and secondary infection in patients with COVID-19: a living rapid review and meta-analysis. Clin Microbiol Infect. 2020 Dec;26(12):1622-1629. doi: 10.1016/j.cmi.2020.07.016. Epub 2020 Jul 22. PMID: 32711058.
  2. Riedel S, Melendez JH, An AT, Rosenbaum JE, Zenilman JM. Procalcitonin as a marker for the detection of bacteremia and sepsis in the emergency department. Am J Clin Pathol. 2011 Feb;135(2):182-9.
  3. Oussalah A, Ferrand J, Filhine-Tresarrieu P, Aissa N, Aimone-Gastin I, Namour F, et al. Diagnostic accuracy of procalcitonin for predicting blood culture results in patients with suspected bloodstream infection: an observational study of 35,343 consecutive patients (A STROBE-Compliant Article). Medicine (Baltimore). 2015 Nov;94(44):e1774.