The main purpose of a throat swab culture is to identify the presence of Streptococcus pyogenes, the bacterium responsible for group A streptococcal pharyngitis (strep throat). This test is crucial for confirming bacterial infection, guiding appropriate antibiotic treatment, and preventing complications such as rheumatic fever. Throat swab cultures are highly sensitive and specific for detecting this pathogen, making them the gold standard in diagnosis. Other pathogens like viruses or fungi are not reliably diagnosed with this method. Hence, its primary clinical utility is to detect Streptococcus pyogenes.

Reference: Principles and Practice of Infectious Diseases, Mandell, Douglas, and Bennett, 9th Edition.