Orthopedics

Case Report 

Enterobacter asburiae and Aeromonas hydrophila: Soft Tissue Infection Requiring Debridement

Kevin Koth, DO; James Boniface, MD; Elisha A. Chance, BSAS; Marina C. Hanes, BA

Abstract

Enterobacter asburiae and Aeromonas hydrophila are gram-negative bacilli that have been isolated in soil and water. Enterobacter asburiae can cause an array of diseases, and exposure to A hydrophila can cause soft tissue infections, including necrotizing faciitis.

A healthy-appearing 22-year-old man presented with an innocuous soft tissue injury to his leg due to an all-terrain vehicle crash. He received intravenous antibiotics and was discharged with prophylactic oral antibiotics. After the rapid onset of high fevers (102°F–103°F) <24 hours postinjury, he returned to the emergency department. Emergent surgical debridement was performed, and broad-spectrum intravenous antibiotics were started. Fevers persisted, and the patient underwent repeat extensive surgical debridement and antibiotic bead placement <30 hours after the initial surgical debridement and broad-spectrum antibiotics. Intraoperative cultures found E asburiae and A hydrophila in the wound. Following a long course of antibiotics and a skin graft, he fully recovered and had no functional deficits 1 year postoperatively.

Extensive research revealed that these organisms are rare in soft tissue infections. E asburiae is opportunistic but has not been reported as a primary wound organism, and A hydrophila infections have been reported following motor vehicle crashes involving wound contamination. At presentation, it is challenging to determine rare organisms in a timely fashion; however, emergent extensive surgical intervention of an accelerated aberrant disease process should be considered to avoid catastrophic outcomes.

Abstract

Enterobacter asburiae and Aeromonas hydrophila are gram-negative bacilli that have been isolated in soil and water. Enterobacter asburiae can cause an array of diseases, and exposure to A hydrophila can cause soft tissue infections, including necrotizing faciitis.

A healthy-appearing 22-year-old man presented with an innocuous soft tissue injury to his leg due to an all-terrain vehicle crash. He received intravenous antibiotics and was discharged with prophylactic oral antibiotics. After the rapid onset of high fevers (102°F–103°F) <24 hours postinjury, he returned to the emergency department. Emergent surgical debridement was performed, and broad-spectrum intravenous antibiotics were started. Fevers persisted, and the patient underwent repeat extensive surgical debridement and antibiotic bead placement <30 hours after the initial surgical debridement and broad-spectrum antibiotics. Intraoperative cultures found E asburiae and A hydrophila in the wound. Following a long course of antibiotics and a skin graft, he fully recovered and had no functional deficits 1 year postoperatively.

Extensive research revealed that these organisms are rare in soft tissue infections. E asburiae is opportunistic but has not been reported as a primary wound organism, and A hydrophila infections have been reported following motor vehicle crashes involving wound contamination. At presentation, it is challenging to determine rare organisms in a timely fashion; however, emergent extensive surgical intervention of an accelerated aberrant disease process should be considered to avoid catastrophic outcomes.

Drs Koth and Boniface and Ms Hanes are from the Department of Orthopedics, and Ms Chance is from the Trauma Services Department, St Elizabeth Health Center, Youngstown, Ohio.

Drs Koth and Boniface and Mss Chance and Hanes have no relevant financial relationships to disclose.

The authors thank Barbara Hileman, BA, from the Trauma Research Department at St Elizabeth Health Center for her assistance with editing, and Aurelia Buzulencia, MT, in the Microbiology Department at St Elizabeth Health Center for providing microbiology incidence numbers.

Correspondence should be addressed to: Kevin Koth, DO, Department of Orthopedics, St Elizabeth Health Center, 1044 Belmont Ave, Youngstown, OH 44501 (kothkg@gmail.com).

Enterobacter asburiae belongs to the Enterobacteriaceae family and is normal flora in the gastrointestinal tract but has also been isolated in water and soil.1–3Enterobacter asburiae is most commonly found in immunocompromised patients and is associated with antibiotic use, debilitated states, and chronic respiratory conditions.1,4 Due to the organism’s resistance to ampicillin and cephalosporins, it is usually difficult treat.1,4

Until recently, Aeromonas hydrophila was believed to be mainly a marine and amphibian pathogenic organism.5–8 However, these organisms can act as primary pathogens in human hosts. Few reports have been published of A hydrophila infections resulting from nonaquatic injuries in healthy patients.7–12 Typically, patients who contract A hydrophila are immunocompromised or have sustained burns or trauma in an aquatic environment.7,9,11,13,14

This article describes an injury that initially appeared innocuous. However, over the course of 36 hours after presentation, rapid surgical management was necessary to prevent severe complications. The accelerated progression of this disease process and the unusual organisms—E asburiae and A hydrophila—warrant discussion.

Case Report

A 22-year-old man was transported to a Level I trauma center after sustaining an innocuous-appearing injury to his right leg while riding an all-terrain vehicle in a remote wooded location. Emergency department evaluation found the patient to be afebrile, in mild distress due to pain, and suspicious for a right lower-extremity fracture. However, anteroposterior and lateral radiographs showed no evidence of fracture or radiopaque foreign bodies.

Initial assessment revealed visible debris, but the wound itself was free of gross contamination. Close inspection of the wound revealed an inverted L-shaped, complex laceration of the dermis and subcutaneous fat measuring 4 cm horizontally by 8 cm longitudinally. In the central portion of the wound, a small breach in the gastrocnemius muscle fascia approximately 2 cm in size existed, but the muscle belly was not damaged.

Initial management involved aggressive irrigation and debridement with 1.5 L of sterile saline and a Betadine scrub sponge (Becton Dickinson, Franklin Lakes, New Jersey). The muscle fascia was primarily closed. The patient tolerated the procedure well and was discharged with a prescription for 500 mg cephalexin every 6 hours for 7 days.

The patient returned to the emergency department 12 to 14 hours after initial presentation and reported increasing right leg pain, fever, chills, weakness, and nausea. The wound had mild erythema but no gross purulence, and the compartments were full but compressible. Physical examination revealed a temperature of 104°F, bradycardia, and an elevated white blood cell count of 18.7 E9/L. The patient underwent emergent surgical wound management.

Intraoperatively, exploration showed 3 cm of necrotic skin medial to the laceration; mesomorphic, red, bleeding muscle with contractility; and no evidence of necrotizing fasciitis. Cultures were collected. Due to moderate gram-negative rods reported on the gram stain, vancomycin, ciprofloxacin, and piperacillin/tazobactam were chosen for suspicion of methicillin-resistant Staphylococcus aureus while definitive identification was pending. Twenty-four hours postoperatively, the patient spiked fevers between 102°F and 104°F, and purulence was expressed from the wound.

The second debridement revealed purulence tracking down to the Achilles tendon insertion on the calcaneus. Small amounts of necrotic muscle existed but no frank necrotizing fasciitis. Tobramycin-impregnanted polymethylmethacrylate beads (Stryker, Kalamazoo, Michigan) were placed in the wound, which was provisionally closed with an Ioban occlusive dressing (3M, St Paul, Minnesota) and vacuum-assisted closure (Renasys; Smith & Nephew, St Petersburgh, Florida). These events occurred within 36 hours of initial presentation.

The cultures were positive for moderate E asburiae, resistant to cefazolin and cefoxitin. For A hydrophila, sensitivity studies were not performed because interpretive standards do not exist. When the infection resolved, a full-thickness skin graft was placed by a plastic surgeon. Over the next 8 months, healing occurred at the skin graft and donor sites. At 1 year follow-up, no residual deficits existed, and full function of the right lower extremity was regained.

Discussion

After a comprehensive literature review, no definitive number of specific cases per year could be identified, but the incidence of A hydrophila soft tissue infections are rare and are often reported in case studies.7,8,11,14–17 Gold and Salit15 reported the incidence of A hydrophila soft tissue infections in California between May 1988 and April 1989 to be 0.7 per 1 million people. The current authors examined the microbiology records of 3 sister facilities located in Northeast Ohio between 2000 and 2010. During that time, 284,904 microbiology samples were processed. Ten (0.004%) samples yielded Aeromonas hydrophila, and 16 (0.006%) samples yielded E asburiae (Tables 1, 2).

Aeromonas hydrophila Cases (n=10) from Tri-facility Sample, 2000–2010

Table 1: Aeromonas hydrophila Cases (n=10) from Tri-facility Sample, 2000–2010

Enterobacter asburiae (n=16) Cases from Tri-Facility Sample, 2000–2010

Table 2: Enterobacter asburiae (n=16) Cases from Tri-Facility Sample, 2000–2010

Cases reported in the literature often include an injury in an aquatic environment8,9,13,18; however, water and soil are reported as common sites for Aeromonas and Enterobacter.1,10,14A hydrophila infections have been reported following motor vehicle crashes, farmyard injuries, puncture injuries, and mud football injuries involving wound contamination from aquatic and nonaquatic environments.5,10,14,19,20

Literature on E asburiae is equally anomalous. A literature search yielded 1 case report concerning a primary respiratory infection with E asburiae.4 In the report by Brenner et al,4 which declares E asburiae as its own species, most isolates studied were obtained from men, one-fourth of the isolates were from people aged 16 to 44 years, and approximately 10% of the isolates were obtained from wounds and exudates. No reports have been published of E asburiae being a primary organism in a wound infection. In the current patient, because wound cultures were not obtained on first presentation and the patient was discharged for 12 hours before he returned, it is unknown whether the organism was present in the wound on presentation or if it was community-acquired. The host environment for this organism is still unknown,4 but it has been isolated from water and soil samples1,3 and may have been present in the wooded area where the patient was injured. It is also plausible that E asburiae was opportunistic in this case due to the concomitant infection of A hydrophila. To the authors’ knowledge, this is the first reported incidence of A hydrophila and E asburiae as primary wound organisms appearing simultaneously in a healthy, young man who was not injured in an aquatic environment.

Literature reviews and case reports note fever as a primary clinical presentation, along with other nonspecific signs of infection that present within 8 to 48 hours after injury.6,14 After initial discharge, the current patient developed high fevers within 12 hours postinjury, even with thorough wound cleansing and routine antibiotic administration. Pyrexia and wound purulence persisted despite emergent surgical debridement and broad-spectrum antibiotic administration. The decision to explore the wound and provide an extensive debridement after the previous treatment and intravenous antibiotics was critical to the favorable outcome in this case.

Conclusion

Although it is impossible to know the exact organism at presentation and prophylactic treatment for a rare organism is impractical, rapid identification of an aberrant disease process is paramount. When presented with an innocuous-appearing injury and rapidly progressive symptoms, emergent extensive surgical intervention should be considered, especially in instances where high fevers persist despite appropriate antibiotic therapy.

References

  1. Angoules AG, Lindner T, Vrentzos G, Papakostidis C, Giannoudis PV. Prevalence and current concepts of management of farmyard injuries. Injury. 2007; 38:S26–S33. doi:10.1016/j.injury.2007.10.031 [CrossRef]
  2. Archer BJ, Holm RP. Treatment of Aeromonas hydrophila infection in a deep tissue wound. S D J Med. 1995; 48:405–407.
  3. Borger van der Burg BLS, Bronkhorst MWGA, Pahlplatz PVM. Aeromonas hydrophila necrotizing fasciitis. J Bone Joint Surg Am. 2006; 88:1357–1360. doi:10.2106/JBJS.C.00923 [CrossRef]
  4. Brenner DJ, McWhorter AC, Kai A, Steigerwalt AG, Farmer JJ III, . Enterobacter asburiae sp. nov., a new species found in clinical specimens, and reassignment of Erwinia dissolvens and Erwinia nimipressuralis to the genus Enterobacter as Enterobacter dissolvens comb. nov. and Enterobacter nimipressuralis comb. nov. J Clin Microbiol. 1986; 23:1114–1120.
  5. DeGascun CF, Rajan L, O’neill E, Downey P, Smyth EG. Pancreatic abscess due to Aeromonas hydrophila. J Infection. 2007; 54:E59–E60. doi:10.1016/j.jinf.2006.03.037 [CrossRef]
  6. Hazen TC, Fliermans CB, Hirsch RP, Esch GW. Prevalence and distribution of Aeromonas hydrophila in the United States. Appl Environ Microbiol. 1978; 36:731–738.
  7. Heckerling PS, Stine TM, Pottage JC Jr, Levin S, Harris AA. Aeromonas hydrophila myonecrosis and gas gangrene in a nonimmunocompromised host. Arch Intern Med. 1983; 143:2005–2007. doi:10.1001/archinte.1983.00350100189036 [CrossRef]
  8. Joseph SW, Daily OP, Hunt WS, Seidler RJ, Allen DA, Colwell RR. Aeromonas primary wound infection of a diver in polluted waters. J Clin Microbiol. 1979; 10:46–49.
  9. Minnaganti VR, Patel PJ, Iancu D, Schoch PE, Cunha BA. Necrotizing fasciitis caused by Aeromonas hydrophila. Heart Lung. 2000; 29:306–308. doi:10.1067/mhl.2000.106723 [CrossRef]
  10. Ogle JW, Anderson MS. Infections: bacterial & spirochetal. In: Hay WW, Levin MJ, Sondheimer JM, Deterding RR, eds. Current Diagnosis & Treatment: Pediatrics. 20th ed. New York, NY: McGraw Hill; 2011. http://www.accessmedicine.com/content.aspx?aID=6590638. Accessed April 13, 2011.
  11. Purdy CW, Clark RN, Straus DC. Determination of water quality variables, endotoxin concentration, and Enterobacteriaceae concentration and identification in southern High Plains dairy lagoons. J Dairy Sci. 2010; 93:1511–1522. doi:10.3168/jds.2009-2497 [CrossRef]
  12. Sanger JR, Yousif NJ, Matloub HS. Aeromonas hydrophila upper extremity infection. J Hand Surg Am. 1989; 14:719–721. doi:10.1016/0363-5023(89)90198-6 [CrossRef]
  13. Semel JD, Trenholme G. Aeromonas hydrophila water-associated traumatic wound infections: A review. J Trauma. 1990; 30:324–327. doi:10.1097/00005373-199003000-00011 [CrossRef]
  14. Stewart JM, Quirk JR. Community-acquired pneumonia caused by Enterobacter asburiae. Am J Med. 2001; 111:82–83. doi:10.1016/S0002-9343(01)00791-4 [CrossRef]
  15. Gold WL, Salit IE. Aeromonas hydrophila infections of skin and soft tissue: report of 11 cases and review. Clin Infect Dis. 1993; 16:69–74. doi:10.1093/clinids/16.1.69 [CrossRef]
  16. Tsai YH, Wen-Wei Hsu R, Huang TJ, et al. Necrotizing soft-tissue infections and sepsis caused by Vibrio vulnificus compared with those caused by Aeromonas species. J Bone Joint Surg Am. 2007; 89:631–636. doi:10.2106/JBJS.F.00580 [CrossRef]
  17. Ulla-Britt L, Ulett D, Garrison T, Rockett MS. Aeromonas hydrophila infections after penetrating foot trauma. J Foot Ank Surg. 2003; 42:305–308. doi:10.1016/S1067-2516(03)00305-3 [CrossRef]
  18. Vally H, Whittle A, Cameron S, Dowse GK, Watson T. Outbreak of Aeromonus hydrophila wound infections associated with mud football. Clin Infect Dis. 2004; 38:1084–1089. doi:10.1086/382876 [CrossRef]
  19. Vukmir RB. Aeromonas hydrophila: myofascial necrosis and sepsis. Intensive Care Med. 1992; 18:172–174. doi:10.1007/BF01709242 [CrossRef]
  20. Young DF, Barr RJ. Aeromonas hydrophila infection of the skin. Arch Dermatol. 1981; 117:244. doi:10.1001/archderm.1981.01650040060025 [CrossRef]

Aeromonas hydrophila Cases (n=10) from Tri-facility Sample, 2000–2010

Year Source Sex Age
2001 Stool F 42
2001 Stool F 35
2003 Wound F 12
2005 Sputum M 29
2006 Stool M 75
2008 Wound F 44
2009 Wound M 22
2010 Wound M 18
2010 Wound F 37
2010 Wound M 64

Enterobacter asburiae (n=16) Cases from Tri-Facility Sample, 2000–2010

Year Source Sex Age
2007 Sputum M 26
2007 Sputum F 84
2008 Sputum M 53
2008 Urine M 56
2008 Sputum F 90
2009 Wound F 54
2009 Wound M 22
2009 Urine M 66
2009 Wound F 48
2009 Wound F 85
2009 Urine M 66
2010 Blood M 50
2010 Wound M 9
2010 Sputum F 81
2010 Urine F 49
2010 Wound F 84
Authors

Drs Koth and Boniface and Ms Hanes are from the Department of Orthopedics, and Ms Chance is from the Trauma Services Department, St Elizabeth Health Center, Youngstown, Ohio.

Drs Koth and Boniface and Mss Chance and Hanes have no relevant financial relationships to disclose.

Correspondence should be addressed to: Kevin Koth, DO, Department of Orthopedics, St Elizabeth Health Center, 1044 Belmont Ave, Youngstown, OH 44501 (kothkg@gmail.com).

10.3928/01477447-20120525-52

Sign up to receive

Journal E-contents