ADVERTISEMENT
Identifying And Treating Soft Tissue Infections Following Water Exposure
With the arrival of warmer weather, individuals spend an increased amount of time outdoors, often in water environments engaged in recreational activity. Trauma secondary to encounters with aquatic animals or environmental injury can predispose people to secondary soft tissue infections. Both freshwater and saltwater environments can harbor unique bacteria, leading to soft tissue infections with pathogens that are quite different from those in dry environments.
With wading and walking in water environments where it is often difficult to see the ground surface, trauma leading to soft tissue infection is commonly localized to the foot and ankle and can result from puncture wounds, lacerations, abrasions and animal bites. Injury in many different water types, including fresh water, salt water, brackish water and swimming pools, can lead to secondary bacterial infection. A wide array of bacteria can cause infection after water exposure. Some of the most common bacteria causing soft tissue infection after water exposure include Aeromonas species, Edwardsiella tarda, Erysipelothrix spp., Vibrio vulnificus and Mycobacterium marinum.
An increased predilection for male gender is a curious feature of both Aeromonas and Vibrio spp. infections. A Mayo Clinic series examining Aeromonas soft tissue infections found that 90 percent of the cases occur in males.1 Currently, no research has found increased participation of males in outdoor activity to explain this association and to date, there is no explanation of the male predominance in Aeromonas infections.1 A similar male predominance occurs in Vibrio species infections with approximately 75 percent of these infections occurring in males.2,3 Animal studies have shown that high serum iron is associated with increased mortality from Vibrio infections and researchers hypothesize that reduced iron stores in females may confer a protective effect against Vibrio infection.4,5
Infections secondary to bacteria in water environments can produce a variety of soft tissue infections of variable severity. Underlying systemic illnesses can increase the risk of developing a soft tissue infection and also increase the severity of infection when it does occur. Both hepatic disease and cancer increase the risk of infection due to Aeromonas spp., Vibrio and E. tarda.6-8
Several waterborne bacteria produce characteristic soft tissue infections, including cellulitis, abscess formation, ecthyma gangrenosum, necrotizing myositis and necrotizing fasciitis.8 Both Aeromonas and Vibrio infections have been associated with rapidly progressive soft tissue infections leading to disseminated systemic disease. Aeromonas most commonly causes localized cellulitis but can also cause severe wound infections including myonecrosis, rhabdomyolysis and ecthyma gangrenosum-like skin lesions.9-11 Vibrio infections are frequently characterized by aggressive soft tissue infection with bulla formation and soft tissue necrosis.12
Erysipelothrix spp. and Mycobacterium marinum are associated with indolent cutaneous infections without systemic manifestations. Erysipelothrix spp. infections commonly produce erysipeloid, a localized cutaneous infection characterized by well-demarcated tender, warm, purple plaques that leave brown discoloration while they are resolving.13 Mycobacterium marinum infections typically present as papules on an extremity, frequently the dorsal foot, and progress to shallow ulcerations that heal with scarring.14 Edwardsiella tarda shows an intermediate course causing cellulitis with occasional systemic infection in immuno-compromised hosts. Edwardsiella tarda infections have a variable presentation ranging from simple cellulitis to bacteremia and sepsis.6
One should obtain a Gram stain and culture from wound drainage or a soft tissue biopsy to identify causative organisms. In cases in which microbiologic data is not available, recent exposure history (travel, occupational exposure, etc.) can provide clues regarding causative agents and guide empiric antibiotic selection. In immunocompromised individuals and patients presenting with systemic symptoms, one should obtain blood cultures and laboratory data including a complete blood cell count with differential, chemistry panel, erythrocyte sedimentation rate and C-reactive protein. Laboratory values can be helpful in determining inpatient versus outpatient management as well as monitoring disease response to therapy.
What You Should Know About Treating Specific Pathogens
Treatment of waterborne infections should begin with the assessment of systemic involvement and host factors, namely immune compromise, and determining whether patients require outpatient treatment or hospitalization for intravenous antibiotics and possible surgical intervention.
Clinicians should start patients on empiric antibiotics pending culture results. Exposure history can also be helpful in guiding empiric antibiotic selection. I recommend that empiric antibiotics include coverage for streptococci and Staph aureus as these are the most common bacteria causing soft tissue infection. Additionally, I recommend broad-spectrum antibiotics for water-related infections as these are frequently polymicrobial.15 Following the identification of causative organisms, one may use narrow broad-spectrum antibiotics to cover the specific infecting bacteria. Base antibiotic therapy upon susceptibility testing of the specific bacterial isolates.
See below for recommended treatment regimens for specific common waterborne bacteria that can cause soft tissue infection.
Aeromonas. Authors recommend antibiotic treatment for Aeromonas soft tissue infections and bacteremia.16 Most Aeromonas strains are susceptible to trimethoprim-sulfamethoxazole (Bactrim, Roche), fluoroquinolones, second- and third-generation cephalosporins, aminoglycosides, carbapenems, chloramphenicol and tetracyclines.17
Edwardsiella tarda. Antibiotic treatment is the recommended therapy for E. tarda infections. Most isolates are susceptible to ampicillin, cephalosporins, aminoglycosides and trimethoprim-sulfamethaoxazole.8,18
Erysipelothrix rhusiopathiae. Erysipeloid skin lesions can resolve spontaneously over the course of several weeks but antibiotic therapy can shorten the clinical course and prevent relapse.19 Penicillin is the drug of choice for Erysipelothrix rhusiopathiae infection with clindamycin or ciprofloxacin (Cipro, Bayer) recommended for patients with penicillin allergy.20
Vibrio vulnificus. When it comes to mild wound infection in patients without immune compromise, clinicians can perform local wound care and utilize oral antibiotics. Severe Vibrio wound infections require surgical debridement and intravenous antibiotic therapy. V. vulnificus can lead to septicemia with a high fatality rate.21 Patients with V. vulnificus septicemia should have aggressive management in an intensive care unit with antibiotic therapy and supportive care. Recommended antibiotic regimens for V. vulnificus infections include a third-generation cephalosporin and a tetracycline; third-generation cephalosporin and minocycline or ciprofloxacin; and fluoroquinolones.22-24
Mycobacterium marinum. Authors have reported numerous treatment modalities for cutaneous Mycobacterium marinum lesions including monitoring, surgical excision, anti-tuberculous agents and antibiotics.25 Most M. marinum isolates are susceptible to rifampin, ethambutol, clarithromycin, sulfonamides and trimethoprim-sulfamethoxazole.13 For infections with M. marinum, I recommend a combination of two susceptible antibiotic agents and continuing that treatment for three to four months, extending therapy one to two months following the resolution of symptoms.13,26,27 Surgical treatment is recommended for lesions that fail to respond to conservative treatment.28
In Conclusion
Traumatic injuries in water environments can lead to secondary soft tissue bacterial infections. The most common waterborne organisms leading to soft tissue infection include Aeromonas species, Edwardsiella tarda, Erysipelothrix spp., Vibrio vulnificus and Mycobacterium marinum. Initial broad-spectrum antibiotic treatment is the recommended treatment with subsequent narrowing based on culture and sensitivity results. Hospitalization, parental antibiotics and surgical debridement may be required for severe infections.
References
1. Baddour LM. Extraintestinal Aeromonas infections--looking for Mr. Sandbar. Mayo Clinic Proc. 1992;67(5):496-498.
2. Tacket CO, Brenner F, Blake PA. Clinical features and an epidemiological study of Vibrio vulnificus infections. J Infect Dis. 1984;149(4):558-561.
3. Levine WC, Griffin PM. Vibrio infections on the Gulf Coast: results of first year of regional surveillance. Gulf Coast Vibrio Working Group. J Infect Dis. 1993;167(2):479-483.
4. Oliver JD. Vibrio vulnificus: death on the half shell. A personal journey with the pathogen and its ecology. Microbial Ecol. 2013;65(4):793-799.
5. Oliver JD. Wound infections caused by Vibrio vulnificus and other marine bacteria. Epidemiol Infect. 2005;133(3):383-391.
6. Janda JM, Abbott SL. Infections associated with the genus Edwardsiella: the role of Edwardsiella tarda in human disease. Clin Infect Dis. 1993;17(4):742-748.
7. Baddour LM, Baselski VS. Pneumonia due to Aeromonas hydrophila-complex: epidemiologic, clinical, and microbiologic features. Southern Med J. 1988;81(4):461-463.
8. Czachor JS. Unusual aspects of bacterial water-borne illnesses. Am Fam Phys. 1992;46(3):797-804.
9. Tena D, Aspiroz C, Figueras MJ, et al. Surgical site infection due to Aeromonas species: report of nine cases and literature review. Scand J Infect Dis. 2009;41(3):164-170.
10. Tena D, Gonzalez-Praetorius A, Perez-Pomata MT, Bisquert J. [Rapidly progressive myonecrosis by Aeromonas veronii biotype sobria]. Anales de medicina interna. 2006;23(11):540-542.
11. Adamski J, Koivuranta M, Leppanen E. Fatal case of myonecrosis and septicaemia caused by Aeromonas hydrophila in Finland. Scand J Infect. 2006;38(11-12):1117-1119.
12. Blake PA, Merson MH, Weaver RE, Hollis DG, Heublein PC. Disease caused by a marine Vibrio. Clinical characteristics and epidemiology. N Engl J Med. 1979;300(1):1-5.
13. Wang Q, Chang BJ, Riley TV. Erysipelothrix rhusiopathiae. Vet Microbiol. 2010;140(3-4):405-417.
14. Aubry A, Chosidow O, Caumes E, Robert J, Cambau E. Sixty-three cases of Mycobacterium marinum infection: clinical features, treatment, and antibiotic susceptibility of causative isolates. Arch Intern Med. 2002;162(15):1746-1752.
15. Voss LM, Rhodes KH, Johnson KA. Musculoskeletal and soft tissue Aeromonas infection: an environmental disease. Mayo Clinic Proc. 1992;67(5):422-427.
16. Vila J, Marco F, Soler L, Chacon M, Figueras MJ. In vitro antimicrobial susceptibility of clinical isolates of Aeromonas caviae, Aeromonas hydrophila and Aeromonas veronii biotype sobria. J Antimicrob Chemother. 2002;49(4):701-702.
17. Aravena-Roman M, Inglis TJ, Henderson B, Riley TV, Chang BJ. Antimicrobial susceptibilities of Aeromonas strains isolated from clinical and environmental sources to 26 antimicrobial agents. Antimicrob Agents Chemother. 2012;56(2):1110-1112.
18. Wilson JP, Waterer RR, Wofford JD, Jr., Chapman SW. Serious infections with Edwardsiella tarda. A case report and review of the literature. Arch Intern Med. 1989;149(1):208-210.
19. Reboli AC, Farrar WE. Erysipelothrix rhusiopathiae: an occupational pathogen. Clin Microbiol Rev. 1989;2(4):354-359.
20. Veraldi S, Girgenti V, Dassoni F, Gianotti R. Erysipeloid: a review. Clin Exper Dermatol. 2009;34(8):859-862.
21. Klontz KC, Lieb S, Schreiber M, Janowski HT, Baldy LM, Gunn RA. Syndromes of Vibrio vulnificus infections. Clinical and epidemiologic features in Florida cases, 1981-1987. Ann Intern Med. 1988;109(4):318-323.
22. Liu JW, Lee IK, Tang HJ, et al. Prognostic factors and antibiotics in Vibrio vulnificus septicemia. Arch Intern Med. 2006;166(19):2117-2123.
23. Chen SC, Lee YT, Tsai SJ, et al. Antibiotic therapy for necrotizing fasciitis caused by Vibrio vulnificus: retrospective analysis of an 8 year period. J Antimicrob Chemother. 2012;67(2):488-493.
24. Tang HJ, Chang MC, Ko WC, Huang KY, Lee CL, Chuang YC. In vitro and in vivo activities of newer fluoroquinolones against Vibrio vulnificus. Antimicrob Agents Chemother. 2002;46(11):3580-3584.
25. Collins CH, Grange JM, Noble WC, Yates MD. Mycobacterium marinum infections in man. J Hygiene. 1985;94(2):135-149.
26. Griffith DE, Aksamit T, Brown-Elliott BA, et al. An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respirator Crit Care Med. 2007;175(4):367-416.
27. Lewis FM, Marsh BJ, von Reyn CF. Fish tank exposure and cutaneous infections due to Mycobacterium marinum: tuberculin skin testing, treatment, and prevention. Clin Infect Dis. 2003;37(3):390-397.
28. Chow SP, Ip FK, Lau JH, et al. Mycobacterium marinum infection of the hand and wrist. Results of conservative treatment in twenty-four cases. J Bone Joint Surg Am. 1987;69(8):1161-1168.
