Differential Diagnosis for Septic Arthritis of the Left Thumb
Single Most Likely Diagnosis
- Staphylococcal septic arthritis: This is the most likely diagnosis given the history of a laceration and the development of septic arthritis. Staphylococcus aureus is a common cause of skin infections and can lead to septic arthritis, especially if the laceration became infected.
Other Likely Diagnoses
- Streptococcal septic arthritis: Similar to Staphylococcus, Streptococcus species can cause septic arthritis, particularly in the context of a recent skin infection or laceration.
- Gonococcal septic arthritis: Although less common, Neisseria gonorrhoeae can cause septic arthritis, especially in sexually active individuals. The fact that the patient has been on doxycycline (which is used to treat gonorrhea) for a week might suggest this possibility, but it's less likely given the context of a laceration.
- Polymicrobial septic arthritis: Infections involving multiple bacteria can occur, especially if the laceration was contaminated with dirt or other foreign material.
Do Not Miss Diagnoses
- Osteomyelitis: Infection of the bone adjacent to the septic joint, which can occur simultaneously or as a complication of septic arthritis. Missing this diagnosis could lead to prolonged infection and bone damage.
- Tendon or ligament rupture: Infection can weaken tendons and ligaments, leading to rupture. Early recognition is crucial to prevent long-term disability.
- Necrotizing fasciitis: A severe infection of the fascia that can spread rapidly and is life-threatening if not promptly treated.
Rare Diagnoses
- Fungal septic arthritis: Fungal infections are rare causes of septic arthritis but should be considered in immunocompromised patients or those with a history of fungal infections.
- Mycobacterial septic arthritis: Infections caused by Mycobacteria, such as tuberculosis, can cause septic arthritis, especially in endemic areas or in immunocompromised individuals.
- Brucellar septic arthritis: Brucella species can cause septic arthritis, particularly in individuals who work with animals or consume unpasteurized dairy products.