What constitutes an adequate sputum sample for microbiological examination?

An adequate sputum sample for microbiological examination is characterized by having a low number of squamous epithelial cells and a higher count of leukocytes. The rationale is that the presence of squamous cells indicates contamination from the oropharynx, while leukocytes, particularly neutrophils, suggest the existence of an inflammatory response, which is often indicative of an infection in the lower respiratory tract.

In this case, having less than 10 squamous cells allows us to ascertain that the specimen is derived from the lower respiratory tract rather than being contaminated by saliva. Conversely, having over 25 leukocytes per low power field (LPF) demonstrates a robust inflammatory response, which strengthens the likelihood that the specimen contains relevant microbial pathogens that require evaluation.

By adhering to these criteria, clinicians can ensure that the sputum sample is representative of the lung secretions where infection may be present, ultimately leading to more accurate diagnoses and appropriate management of respiratory conditions.