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Case Report, Global Climate Change and Wound Care: Case Study of an Off-season Vibrio alginolyticus Infection in a Healthy Man
Abstract
Vibrio alginolyticus is a halophilic Gram-negative bacterium normally present in seawater. Vibrios are not capable of cutaneous invasion through intact skin and their isolation from extraintestinal sites is uncommon. However, interruptions in skin integrity (cuts or abrasions) can allow these bacteria to cause complicated skin and soft tissues infections.
This case study describes the clinical assessment and management of a nonhealing traumatic wound, sustained in a coastal area during the winter months, in a healthy 70-year-old man. Culture results were positive for V. alginolyticus. Appropriate antibiotic treatment and topical wound care successfully resolved the infection. V. alginolyticus infections are usually benign; respond well to treatment, even with local therapy only; and tend to result from contact with warm ocean water. The clinical characteristics of the wound prompted a suspicion of a Vibrio infection even though the wound was sustained in the winter time and the patient did not have direct contact with ocean water. Although other case studies of Vibrio infections in the absence of direct contact with ocean water have been published, increased ocean temperatures due to global climate changes may explain the out-of-season infection in this patient. Clinicians should monitor the progression of wound healing and be prepared to modify treatment based on individual circumstances, especially in the case of unusual wound presentation, nonhealing, or a progressing wound infection.
Vibrio alginolyticus is a halophilic Gram-negative, motile, curved bacterium and one of the 12 Vibrio species responsible for human infections.1-4 It is present in seawater with a worldwide distribution.1 Global warming has resulted in increased marine temperatures with an expected diffusion of these pathogens to northern global regions.5-7 Among Vibrio species, the most commonly related to skin and soft tissues infection are V. vulnificus, V. parahaemolyticus, V. alginolyticus, and V. damsela.8–12
Patient history of persons infected with Vibrios usually shows a recent exposure to seawater,12-18 although cases without specific exposure have been reported.19-23 Normally, Vibrios are not capable of cutaneous invasion through intact skin; however, the presence of cuts (wounds) or abrasions provides a portal of entry and explains the high incidence of Vibrio-related wound infections in bathers and persons involved in other marine 
activities.12,14,19,21,24,25 The majority of V. alginolyticus isolates have been found in patients with skin and soft tissues infections,7,12,19,22,24,26-31 including ulcers and abscesses, necrotizing fasciitis,13,15,32,33 cellulitis,12,18,34 and infections of the ear (otitis media and otitis externa).7,12,19,20,22,25,27,35 A case of V. alginolyticus peritonitis associated with peritoneal dialysis also has been reported.36 Other rare complications are gastroenteritis (in immunocompromised patients),37,38 intracranial infection following an injury in saltwater,17 pleural empyema (in an immunocompromised patient),39 and bacteremia.26,39-41 Infections due to V. alginolyticus are usually benign and respond well to local therapy.
Case Study
Mr. S. presented at the authors’ outpatient service with a post-traumatic wound infection. The 70-year-old healthy Caucasian man had no history of diabetes or smoking and was not taking any prescription medications. He had sustained a limited penetrating trauma of the medial surface of the right leg (distal third) with a lacerated contused wound after a fall from his bicycle during a ride by the Adriatic Sea in the winter. His wound initially was treated by his family physician with surgical debridement, conventional dressings, and no antibiotic therapy (a tetanus booster had been administered within 5 years of the injury) and cleaned daily with an antiseptic solution (povidone iodine). Despite this daily attention, after 10 days the wound developed a central area of necrosis and progressively worsened, developing a wider central necrotic area with hyperemic irregular edges and serosanguinous exudation.
After more than 2 months with no improvement, Mr. S presented at the authors’ surgical outpatient service. At the time of observation, the wound had a central excavated necrotic area in the shape of a crater with irregular edges and a wide surrounding hyperemic area. It was exuding pus. The leg was functionally impaired and painful both at rest and on walking. No signs of systemic inflammation were present: body temperature was normal and the leukocyte count was within the normal values, with normal proportions of polymorphonuclear cells.
Color Doppler ultrasonography of the right lower limb was performed to evaluate possible venous insufficiency. An x-ray of the right leg was obtained to exclude osteomyelitis.
Two biopsy samples of the lesion were taken for microbiological investigation and empirical antibiotic treatment with levofloxacin (500 mg twice daily) was started, together with local medication with salicylic acid plus sodium iodide (Fertomcidina, Theriaca Srl, Italy). Both biopsy samples produced pure cultures of Gram-negative, oxidase-positive organisms that grew on thiosulfate-citrate-bile salts-sucrose agar. The isolates presumptively were identified as V. alginolyticus by the Vitek® 2 system (bioMérieux, Inc, Hazelwood, MO). Species-level identification was further confirmed with manual tests (growth at high concentration of NaCl [up to 8%] and reactions to urea, indole, arginine, ornithine, lysine, glucose, sucrose, lactose, threalose, arabinose, gelatine, acetate, and the Voges-Proskauer test). Bacterial DNA was extracted from culture isolates using a QIAmp® DNA Mini kit (Qiagen, Hilden, Germany). Sequence analysis of the PCR-amplified 16S rRNA genes revealed 99% homology with the prototype strain sequence of V. alginolyticus ATCC 177497. In vitro antimicrobial susceptibility testing using the Etest® (AB Biodisk, Solna, Sweden) confirmed susceptibility to levofloxacin (minimum inhibitory concentration [MIC], 0.38 mg/L 0.38 mg/L) and additionally yielded the following MICs: amoxycillin-clavulanic acid, 4 mg/L; cefotaxime, 0.19 mg/L; ceftazidime, 0.25 mg/L; ciprofloxacin, 0.38 mg/L; doxycycline, 0.38 mg/L; meropenem, 0.125 mg/L; tetracycline, 0.5 mg/L; and trimethoprim-sulphamethoxazole, 0.19 mg/L. Cultures for anaerobes and mycobacteria yielded no growth.
On the basis of these results, levofloxacin therapy was continued for a total of 20 days (500 mg twice daily for 7 days, followed by 750 mg once daily). After the first week, Mr. S’s condition improved (see Figure 1). The pain resolved, leg functionality returned, and purulent exudation lessened. After the second week, necrosis decreased slightly and local inflammation was responding favorably to treatment (see 
Figure 2). After 1 month, the slow healing process resulted in wound remargination with the complete disappearance of the hyperemic area (see Figure 3).
Discussion
The different micro-organisms in any wound are influenced by various wound (type, depth, location) and host (tissue perfusion, efficacy of the immune response) characteristics. Wound contaminants usually originate from three main sources: the environment (exogenous micro-organisms in the air or introduced by traumatic injury), the surrounding skin (involving members of the normal skin microflora such as Staphylococcus epidermidis, micrococci, skin diphtheroids), and endogenous factors involving mucous membranes (gastrointestinal, oropharyngeal, genitourinary mucosa). In Mr. S’s case, initial wound management reflected the family physician’s supposition that the wound contaminants were common micro-organisms belonging to the surrounding skin and to soil. Thus, the clinician applied standard wound management: normal and compressive dressing, disinfection with antiseptic solution, wound cleansing, and repeated surgical debridement.
V. alginolyticus was the only invasive pathogen isolated after 2 months. No other micro-organisms were identified. In this case study, the infection was directly related to neither previous swimming nor any direct contact with seawater, although the wound was incurred near the beach. Presentation was unusual because the injury/contamination occurred during the winter months, when water temperature and levels of Vibrio species are generally lower. The wound characteristics on presentation (emergence of a new area of hyperemia, with irregular edges, central necrosis, disability, and lack of sensation near the trauma site) were unusual and prompted an investigation to identify the pathogen, resulting in definitive therapy of a simple but prolonged and painful wound infection.
Conclusion
Infections due to V. alginolyticus are usually benign and respond well to local therapy. However, in any patient with a nonhealing wound infection associated with swimming or trauma occurring in coastal areas, V. alginolyticus should be considered among the possible suspected causative organisms, not only in warm seasons but throughout the year, considering the increased marine temperature due to global warming.
Dr. Sganga is Associate Professor of Surgery, Department of Surgery; Dr. Cozza is a General Surgery Resident, Department of Surgery; Dr. Spanu is a Research Fellow, Department of Microbiology; Dr, Spada is a Research Fellow, Department of Surgery; and Dr. Fadda is Professor and Chairman of Microbiology, Department of Microbiology, Catholic University of Sacred Heart, Rome, Italy. Please address correspondence to Gabriele Sganga, Catholic University of Sacred Heart, Department of Surgery, Policlinico “A. Gemmelli”, Largo A. Gemmelli 8, 00168 Roma, Italy; email: gsganga@tiscali.it.
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