Figure A shows an abscess over the metacarpophalangeal joint of the thumb. Infections with these characteristics in IV drug abusers are most commonly caused by MRSA, and can affect any portion of the hand.
Imahara et al retrospectively reviewed 159 hand infections treated in the operating room over an 11-year period. The examined data included known risk factors for MRSA, including human immunodeficiency virus infection, diabetes mellitus, intravenous drug use, incarceration, and homelessness. Intravenous drug use was the only independent risk factor for CA-MRSA infections.
Boucher et al examined the trends in both nosocomial and community-associated MRSA infections and explored recent studies of the mechanisms that allow S. aureus to become resistant to currently available drugs.
1-Herpes simplex virus can cause Herpetic whitlow, as shown in Illustration A, typically presents on the fingers health care workers exposed to a carriers mouth. Usually, this infection appears as small ulcers or vesicles, and operative debridement is contraindicated.
2-Candida albicans is a more rare hand infection typically associated with chronic paronychia, as shown in Illustration B.
3-Escherichia coli is a less common cause of abscess formation in the hand.
4-Eikenella is usually associated with "fight-bite" infections on the dorsal aspect of the MCP joint, and does not commonly occur after superficial lacerations. It can also rarely occur in IV drug users who clean their needles with saliva, as Eikenlla is part of the normal oral flora. An example of a Eikenella infection is shown in Illustration C.
Imahara SD, Friedrich JB. Community-acquired methicillin-resistant Staphylococcus aureus in surgically treated hand infections. J Hand Surg Am. 2010 Jan;35(1):97-103. Epub 2009 Dec 4.
PMID:19962836 (Link to Abstract)
Boucher HW, Corey GR. Epidemiology of methicillin-resistant Staphylococcus aureus. Clin Infect Dis. 2008 Jun 1;46 Suppl 5:S344-9. Review.
PMID:18462089 (Link to Abstract)