Gram – Sputum: <25/lpf (1-9/lpf) squamous epithelial cells, <25/lpf (none) neutrophils; gram positive cocci (viridans group streptococci), gram negative diplococci (Moraxella catarrhalis). Specimen suitable for culture – Companion to M162-3 – Shipped August 15, 2016


A simulated sputum smear collected from a 72 year old patient with suspected community acquired pneumonia (CAP) was sent to category A, B, C, and C1 laboratories for Gram staining.

Participants were expected to report the presence of few epithelial cells and a mix of gram positive and negative cocci. Based on the Gram stain the sputum should have been considered SUITABLE FOR CULTURE.



  1. This challenge demonstrated multiple approaches to screen for suitability for culture of sputum samples; dependent upon the criteria and the reader, samples can be accepted or rejected with equal possibility.  This resulted in potentially inconsistent information being provided to clinicians.  This should be a concern for medical laboratories.


Full critique (PDF)

Posted in Clinical Bacteriology Results, critiques, Gram Tagged with: ,