Recognition of Pneumocystis carinii by gram stain in impression smears of lung tissue
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Abstract:
In 12 of 20 (60%) biopsy-proven cases of Pneumocystis carinii pneumonia, the diagnosis was first suggested by examination of routine Gram stains of impression smears made from infected lung tissue and later confirmed by methenamine-silver staining. The cysts appeared as 5- to 7-microns unstained spheres, each containing six to eight intracystic gram-negative bodies (sporozoites). Although the Gram stain does not appear to be as sensitive as more traditional staining techniques for the detection of P. carinii, clinical microbiologists should be aware of the morphology of this organism in gram-stained specimens because this relatively simple procedure gives quick results.
Insights
Routine Gram stains can suggest Pneumocystis carinii pneumonia diagnoses. This quick method identifies the organism
Area of Science:
- Medical Microbiology
- Pulmonary Medicine
- Diagnostic Pathology
Background:
- Pneumocystis carinii pneumonia (PCP) is a significant opportunistic infection.
- Accurate and timely diagnosis of PCP is crucial for patient management.
Purpose of the Study:
- To evaluate the utility of Gram stains for the initial detection of Pneumocystis carinii in lung tissue.
- To describe the morphological characteristics of P. carinii on Gram-stained smears.
Main Methods:
- Analysis of routine Gram stains from 20 biopsy-proven cases of PCP.
- Comparison of Gram stain findings with methenamine-silver staining confirmation.
- Microscopic examination of P. carinii cyst morphology.
Main Results:
- Gram stains suggested PCP in 12 of 20 (60%) cases.
- P. carinii cysts appeared as 5- to 7-micron unstained spheres with 6-8 intracystic gram-negative sporozoites.
- Gram stain sensitivity was lower than methenamine-silver staining but provided rapid preliminary results.
Conclusions:
- Gram staining of lung tissue impression smears can offer a rapid, preliminary method for suggesting Pneumocystis carinii pneumonia.
- Awareness of P. carinii morphology on Gram stains is valuable for clinical microbiologists.
- While not as sensitive as specialized stains, Gram stain's speed is advantageous in initial diagnostic workflows.