Prognostic factors of mycobacterium marinum infection of the hand and wrist

Abstract

Introduction: Mycobacterium marinum infection is prevalent worldwide and is hazardous to people exposed to a marine environment. There is inadequate information on prognostic factors of this infection in the literature. The objective of this study is to identify factors that affect the functional outcome of this condition. Methods: 166 patients treated from 1981 to September of 2009 were included in this prospective study. All patients underwent a biopsy during admission and were followed-up in our special hand infection clinic for at least 2 years. Microbiologists and physiotherapists were part of the management team that assessed these patients during these one or two monthly clinics. Inclusion criteria include exposure to marine environment, history of trauma and positive histology of granulomata by biopsy or culture for mycobacterium marinum. Exclusion criteria include positive culture of organisms other than mycobacterium marinum. Statistical analysis was performed using SPSS version 16.0. Mann-Whitney U nonparametric test and X2 test were used. A P-value of <0.05 was considered significant. Results: A total of 156 patients (94%) completed the entire follow-up period. 131 patients (78.9%) had positive marine exposure. A positive marine exposure was associated with earlier presentation (median of 2 months versus 3.5 months, p=0.001) and less resulting deformity (no deformity versus residual stiffness, p=0.03). Incorrect diagnosis was seen in 100 (60.2%) patients, usually presented late (41 of 98 patients presented later than 3 months) and had intralesional steroids (P=0.000). Steroid injections was associated with longer antibiotic duration (7 months versus 6 months, p=0.017), more debridements (2 versus 1, p=0.026) and resulting deformity (residual stiffness versus no deformity, p=0.00). The antibiotic regime, antibiotic duration or number of postoperative days before mobilization was not associated with long term finger and hand deformity. Conclusion: Patients with risk factors such as positive marine exposure, documented preceding injury and positive histology was associated with earlier consultations and thus lead to less deformity. However, in patients with less obvious presentations, misdiagnosis can have drastic consequences. Misdiagnosis such as trigger finger will lead to intralesional steroid injections, ultimately prolonging antibiotic duration, leading to more debridements and deformities. Similar to other studies worldwide, the antibiotic regime and duration was not associated with long term prognosis for these patients.