Bacterial pneumonia laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Arooj Naz, M.B.B.S
Overview
Patients infected with bacterial pneumonia present with a high leukocyte count as well as elevated inflammatory biomarkers, including ESR and C-RP. Red blood cell and platelet count can also be affected presenting as anemia and thrombocytopenia. Arterial blood gasses will often show changes in pH leading to a respiratory acidosis. Other tests routinely done include electrolyte assessment, renal function tests, pulse oximetry, gram staining and sputum samples. Blood cultures and PCR tests are sensitive tests that can provide a definitive diagnosis and aid in the selection of antibiotics.
Laboratory Findings
CBC[1]
- RBC: Anemia
- WBC: Significant leukocytosis (with left shift), leukopenia may present in cases of atypical pneumonia
- Platelets: Thrombocytopenia
- Electrolytes are particularly helpful but hyponatremia may be present in cases of Legionella
Inflammatory biomarkers[1]
- Erythrocyte sedimentation rate: Elevated
- C-reactive protein: Elevated (> 100 mg/L)
- BUN: elevated
- Hypoxia
- Respiratory acidosis (pH <7.2, bicarbonate <22 mEq/L)
- < 92% indicates severe hypoxia
Blood Culture[1]
- Blood culture samples are necessary in diagnosing the bacterial agent responsible. Samples should be taken before administering antibiotics
- A common practice in hospitalized patients
- Gram staining can identify if an organism is gram positive, gram negative, or does not have a cell wall as in the case of Mycoplasma
- Sputum samples should be obtained when patient presents with a productive cough
- A common practice in hospitalized patients
- PCR results are very rapid and sensitive for detection of bacteria[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "StatPearls". 2021. PMID 30020693.
- ↑ Aydemir O, Aydemir Y, Ozdemir M (2014). "The role of multiplex PCR test in identification of bacterial pathogens in lower respiratory tract infections". Pak J Med Sci. 30 (5): 1011–6. doi:10.12669/pjms.305.5098. PMC 4163223. PMID 25225517.