Not just simple cellulitis: a case report of polymicrobial Aeromonas infection from rural Queensland

Context: The gram-negative organism Aeromonas is found in freshwater and marine environments and can cause a range of diseases in humans, ranging from diarrhoea to cellulitis. Severity of wound infections can vary from mild to severe, ranging from cellulitis to myonecrosis and necrotising fasciitis. Prompt recognition of this pathogen is needed as appropriate treatment involves specific antibiotics to cover this organism. Additionally, consideration of surgical intervention may also be required.
Case report: A Caucasian 39-year-old male injured his right foot falling in a creek bed in the Darling Downs region of rural Queensland, sustaining a laceration in the webbing between his first and second toes. He was seen in two rural hospitals following this event, with oral antibiotics prescribed following his second presentation. Circumstances meant he did not take these, and he finally presented to a third hospital after noting erythema tracking up his leg and discharge emanating from the wound on his foot. He was admitted and commenced on empirical antibiotics; however, severity of the infection necessitated surgical team involvement and multiple debridements. Due to the extend of tissue removed, a skin graft was required. Intraoperative specimens revealed polymicrobial Aeromonas as the causative pathogen.
Lessons learned: This case report documents a polymicrobial soft tissue infection in a young male requiring prompt surgical intervention, even without systemic symptoms of illness. Lack of early recognition of risk factors for infection may have delayed appropriate antibiotic therapy. It highlights the importance of early recognition and appropriate antibiotic cover to prevent spreading infection in individuals in whom Aeromonas may be the suspected pathogen. Empirical antibiotics for cellulitis generally do not include the agents to which Aeromonas is susceptible, hence a regime of trimethoprim/sulfamethoxazole or ciprofloxacin in addition to either dicloxacillin/flucloxacillin is recommended. Initiation of appropriate antibiotics earlier in this case may have prevented the need for surgical intervention. This case also demonstrates that  early surgical referral and intervention may be warranted in suspected Aeromonas infections.