Organism in septic arthritis

Q: Septic arthritis is usually? (select one)

A) Monomicrobial
B) Polymicrobial



Answer: A

In non-immunocompromised and with no history of trauma septic arthritis is usually monomicrobial secondary to staphylococcus aureus. Septic arthritis due to streptococcus pneumoniae is also possible though less likely. Immunocompromised, older, and intravenous (IV) drug abusers may get gram-negative bacilli mono septic arthritis. 

Polymicrobial septic arthritis is seen in either penetrating trauma or polymicrobial bacteremia. Septic arthritis in smaller joints is more tend to be polymicrobial.

#infectious-diseases


References:

1. McBride S, Mowbray J, Caughey W, et al. Epidemiology, Management, and Outcomes of Large and Small Native Joint Septic Arthritis in Adults. Clin Infect Dis 2020; 70:271. 

2. Mathews CJ, Coakley G. Septic arthritis: current diagnostic and therapeutic algorithm. Curr Opin Rheumatol 2008; 20:457.

3. Frazee BW, Fee C, Lambert L. How common is MRSA in adult septic arthritis? Ann Emerg Med 2009; 54:695. 

4. Nelson GE, Pondo T, Toews KA, et al. Epidemiology of Invasive Group A Streptococcal Infections in the United States, 2005-2012. Clin Infect Dis 2016; 63:478. 

5. Ross JJ, Saltzman CL, Carling P, Shapiro DS. Pneumococcal septic arthritis: review of 190 cases. Clin Infect Dis 2003; 36:319. 

6. Allison DC, Holtom PD, Patzakis MJ, Zalavras CG. Microbiology of bone and joint infections in injecting drug abusers. Clin Orthop Relat Res 2010; 468:2107.