First description of wound infection with Vibrio harveyi in Spain

Vibrio harveyi (synonym V. carchariae), is a motile Gram-negative rod which is facultatively anaerobic, halophilic and bioluminescent [1]. It is found free-swimming in tropical marine waters and commensally in the gut microflora of marine animals. It is a pathogen of marine animals [2], [3], although it has been considered nonpathogenic to humans [4]. To our knowledge, only three previous cases of human infection caused by this bacterium have been reported. The first occurred after a shark bite [5], the second was an episode of catheter-related bacteraemia in a British oncologic paediatric patient with a central line after his return from holiday in Perpignan, France, where he had swum in the sea [6], and the third was a wound mixed infection of Photobacterium damselae and Vibrio harveyi in a German man who, on a trip to west Australia, had experienced a laceration injury to the right tibia after falling from a catamaran [7].

Our case occurred in a 49-year-old man referred from the emergency room for cleaning and debridement of an infected wound in the right pretibial region. One week ago, during a trip to the Dominican Republic, he had experienced trauma from striking a bus step. The wound was sutured, and he was given antibiotic treatment with cefadroxil. He subsequently swam in the sea without protecting the bandage from the seawater. At admission, the patient was afebrile and presented a wound on the front and another on the inside of the distal third of the right leg. He was receiving treatment for ankylosing spondylitis with steroids, infliximab and methotrexate. A wound swab was submitted for microbiologic examination. After overnight incubation, a Gram-negative rod, oxidase positive, was isolated and sent for routine identification and susceptibility testing (MicroScan; Beckman Coulter). The next day, no growth was observed, and tests were repeated, adding NaCl up to a 1% final concentration. MicroScan identified the isolate as Vibrio vulnificus (99.9% confidence level). Interestingly, Vibrio harveyi was not in the MicroScan database, but both species share a similar phenotypic pattern, what could account for the high identification confidence level found for Vibrio vulnificus. However, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identified the isolate as Vibrio harveyi (score, 2.021) as well as 16S rRNA sequencing (99.9% similarity with Vibrio harveyi). The susceptibility results are shown in Table 1. Initial treatment with oral ciprofloxacin (500 mg/12 hours) resulted in good response, but due to 0.3% substance loss, an autologous skin graft was also performed, with a favourable outcome. The case presented is the first described in Spain and the third in which Vibrio harveyi is the sole pathogen, despite the expected polymicrobial nature of these kind of infections. Interestingly, two of the four patients reported in the literature, including ours, had impaired immunity.

Table 1.

Susceptibility results of Vibrio harveyi

Antibiotic	MIC (μg/mL)
Amoxicillin/clavulanate	≤8/4
Imipenem	≤1
Piperacillin/tazobactam	≤8
Ertapenem	≤0.5
Cefalotin	16
Gentamicin	8
Cefazolin	16
Tobramycin	4
Cefuroxime	16
Amikacin	16
Cefotaxime	≤1
Nalidixic acid	≤16
Ceftazidime	≤1
Ciprofloxacin	≤0.5
Cefepime	≤1
TMP/SMX	≤2/38
Aztreonam	8
Tigecycline	≤1

MIC, minimum inhibitory concentration; TMP/SMX, trimethoprim/sulfamethoxazole.

Considering that phenotype-based commercial identification systems are problematic for Vibrio species identification [8] and that not all species are listed in their databases, we suggest the use of MALDI-TOF MS or molecular methods in order to establish the true role of species as Vibrio harveyi in these marine-related infections.

Conflict of Interest

None declared.