Final answer:
Streptococcus pneumoniae can be confirmed by a partial agglutination assay, a technique that distinguishes different strains of streptococcal bacteria through serotyping and their unique cell surface proteins.
Step-by-step explanation:
The bacteria that can be confirmed by a partial agglutination assay is Streptococcus pneumoniae. This is due to its unique cell morphology and serological characteristics that can be identified through serotyping and agglutination tests. Rebecca Lancefield's historical development of the technique specifically targeted streptococcal bacteria, and her work led to the classification of Group A strep, where variations of specific cell surface proteins known as M proteins can lead to the identification of different strains via agglutination assays. The quellung reaction is also used for definitive identification of S. pneumoniae.