Aeromonas

Background

Microbiology

• Gram-negative bacillus
• Motile, oxidase positive, catalase positive, nitrate positive, urease negative, glucose fermenting
• Four species of greatest importance to human health include Aeromonas caviae, Aeromonas dhakensis, Aeromonas veronii, and Aeromonas hydrophila
• Aeromonas salmonicida causes disease in fish, with case reports in humans

Epidemiology

• Live in water environments worldwide (including freshwater, saltwater, and wastewater), but also soil, plants, food, animals
• Generally consider opportunistic pathogens

Clinical Manifestations

• Classically, causes skin and soft tissue infections following freshwater exposure or injury
• Also, gastroenteritis and/or colitis, with nausea, vomiting, diarrhea, abdominal pain, and fever
• Bacteremia, with a mortality of about 30%, more common in malignancy, hepatobiliary disease, and diabetes mellitus
• Also reports of respiratory infections, urinary tract infections, and SBP

Management

• Generally susceptible to aminoglycosides, piperacillin, third-generation cephalosporins, carbapenems, azithromycin, nitrofurantoin, quinolones, tetracyclines
• Often susceptible to cotrimoxazole
• Not reliably susceptible to penicillins (except piperacillin), clarithromycin, or first- and second-generation cephalosporins
• Increasingly resistant to beta-lactam antibiotics, with inducible chromosomal beta-lactamases

Further Reading

• The genus Aeromonas: taxonomy, pathogenicity, and infection. Clin Microbiol Rev. 2010 Jan;23(1):35-73. doi: 10.1128/CMR.00039-09. PMID: 20065325; PMCID: PMC2806660.