Staphylococcal or Streptococcal Infection: This is the most common cause of suppurative lymphadenitis, often resulting from a bacterial infection of the skin or soft tissues that spreads to the lymph nodes.

Cat Scratch Disease: Caused by Bartonella henselae, this condition typically presents with lymphadenopathy, often suppurative, following a cat scratch or bite.
Tuberculous Lymphadenitis: Although less common in some regions, tuberculosis can cause suppurative lymphadenitis, especially in areas with high TB prevalence.
Atypical Mycobacterial Infection: Similar to TB, atypical mycobacteria can cause lymphadenitis, which may become suppurative.

Lymphoma: Although lymphoma is not typically suppurative, certain types can present with necrotic or infected nodes, mimicking suppurative lymphadenitis. Missing this diagnosis could be catastrophic.
Kikuchi-Fujimoto Disease: A rare, self-limiting condition that can mimic lymphoma or tuberculosis and may present with suppurative lymphadenitis.
Brucellosis: A zoonotic infection that can cause lymphadenitis among other symptoms, and is critical to diagnose due to its potential for severe complications and person-to-person transmission in rare cases.

Actinomycosis: A chronic bacterial infection that can cause suppurative lymphadenitis, although it is relatively rare and often associated with specific risk factors like poor dental hygiene or immunocompromised states.
Nocardiosis: An infection caused by Nocardia species, which can lead to suppurative lymphadenitis, particularly in immunocompromised individuals.
Toxoplasmosis: While primarily known for causing a non-suppurative lymphadenitis, toxoplasmosis can very rarely present with suppurative nodes, especially in immunocompromised patients.