For a patient presenting with symptoms of pharyngitis, which investigation is appropriate if strep throat is suspected?

In the case of a patient with symptoms of pharyngitis where strep throat is suspected, performing a throat culture is the appropriate investigation. A throat culture is considered the gold standard for diagnosing streptococcal pharyngitis (strep throat). It involves taking a swab from the back of the throat and culturing it in a lab to check for the presence of Group A Streptococcus bacteria.

This method is particularly effective because it can accurately identify the organism responsible for the infection, which is essential for guiding appropriate treatment. Quick and reliable results are critical in managing the patient effectively and preventing complications associated with untreated strep throat, such as rheumatic fever and post-streptococcal glomerulonephritis.

Other options, such as a complete blood count, are not specific to strep throat and would not confirm the diagnosis. A chest x-ray is typically utilized for evaluating respiratory or thoracic conditions rather than throat infections, while allergy testing is unrelated to the diagnosis of strep throat and is not indicated in cases of pharyngitis unless allergies are suspected to be the underlying cause of the symptoms.