Skin and Soft Tissue Infections due to Aeromonas spp.: An Emerging Pathogen

Introduction: Aeromonas spp., the emerging human pathogens, can cause various diseases like gastrointestinal infections, Skin and Soft-Tissue Infections (SSTIs), respiratory tract infections, urinary tract infection, hepatobiliary tract infection, blood stream infections etc. Aeromonas consists of important pathogenic species like Aeromonas hydrophila being the most common one followed by A.sobria, A.veroni, A.caviae and A.salmonicida. SSTIs due to Aeromonads are most often associated with pre-existing ulcer, traumatic wound and exposure to water.

Aim: The present study was carried out to analyse socio-epidemiological factors, clinical features, risk factors and antibiotic resistance potential of Aeromonas spp., SSTIs.

Materials and Methods: In this prospective study, all Gram-negative fermenting motile isolates which are positive for oxidase, H2S production, indole reaction, lysine decarboxylase were further identified by Vitek 2 compact system (Biomerieux, France). The study period was 2 years.

Results: A total of 39 patients with Aeromonas spp., SSTIs were identified during the period from 2020 to 2022. Majority of patients hailed from urban areas, were in middle age group and were farmers. A.hydrophila (n=24, 62%) was the predominant isolate. Majority of the infections were superinfection of wound (n=16, 41%) and chronic non healing ulcer (n=13, 33.3%). A total of 33.3% of infections were polymicrobial, common concomitant pathogens being, Pseudomonas aeruginosa and Methicillin Resistant Staphylococcus aureus (MRSA). Trauma and water exposure were main risk factors with co-morbidities like diabetes, hypertension and liver cirrhosis. A 20.5% of patients were immunocompromised. There was one case of Necrotising Fasciitis (NF) which resulted in patient’s death. Co-trimoxazole, 3rd and 4th generation cephalosporins. Aztreonam and Tigecycline were the most effective antibiotics while eight of the isolates were Multidrug Resistant (MDR). Thirty-three patients recovered completely and three patients died of complications.

Conclusion: Aeromonas hydrophila must be regarded as an emerging pathogen of SSTIs mainly in patients with pre-existing ulcers and can be MDR. Such infections have a good prognosis if prompt medical, surgical and supportive treatment is given.