Mycobacteria that have been involved:
(1) M abscessus
(2) M. chelonae
(3) M fortuitum
(4) M. smegmatis
Risk factors:
(1) using tap water as the source for "sterilized" water used to wash the prosthetic device
(2) immunosuppression (although it occurs in immunocompetent patients)
Clinical features:
(1) joint pain
(2) fever
(3) joint swelling
(4) loosening of the prosthesis
(5) fistula with drainage
Laboratory findings:
(1) elevated erythrocyte sedimentation rate (ESR)
(2) elevated C-reactive protein (CRP)
(3) inflammation in joint fluid
Criteria for diagnosis:
(1) isolation of an atypical mycobacteria on culture of joint aspirate or periprosthetic tissue
(2) evidence of inflammation or other clinical findings of joint infection
The diagnosis may be missed if mycobacterial cultures are not ordered or if insufficient diagnostic material has been collected.
The diagnosis should be considered in a patient with a clinical prosthetic joint infection yet who has negative bacterial cultures or if beaded gram-positive rods are seen on Gram stain.
A false positive diagnosis may be obtained if the specimen or cultures are contaminated with atypical mycobacteria in the hospital water supply. The presence of AFB in tissue samples can help resolve an uncertainty in the diagnosis.
