Aeromonas infection: causes, symptoms, diagnosis, and treatment

Aeromonas can cause mainly diarrhea, wound infection, and bacteremia, merely ocular infections, osteomyelitis, meningitis, respiratory infections, pelvic abscesses, otitis, cystitis, endocarditis, peritonitis, cholecystitis, joint infections, necrotizing fasciitis, and folliculitis.


Causes

Aeromonas is a Gram-negative anaerobic bacterium widely distributed in freshwater, estuarine, and marine environments, is an important pathogen of fishes, and can cause sporadic infections in humans and animals.

Aeromonas has now expanded to 14 phenetic species, including aeromonas hydrophila, aeromonas caviae, aeromonas sobria, aeromonas salmonicida, aeromonas media, aeromonas veronii, and aeromonas jandaei, and 16 genospecies. The type species are aeromonas hydrophila, and aeromonas caviae is the mostly common aeromonas. Aeromonas is widely distributed in water, soil, and air.

Aeromonas hydrophila can produce highly toxic exotoxins such as hemolysin, textilotoxin, necrotoxins, enterotoxins, and proteases.

After aeromonas hydrophila invades the human body, the bacterium reproduces in the intestine, and then enters the liver, kidneys, and other tissues, causing lesions in the liver, kidney, and other organs, as well as sepsis, followed by multiple organ lesions. In severe cases, multiple organ failure may occur. Aeromonas hydrophila infects humans mainly through intestines, whether infection depends on the adhesion of the bacteria to the intestinal tissue, and the adhesion is related to the immune function and basic diseases in humans.

Common clinical species of aeromonas include aeromonas hydrophila, aeromonas caviae, aeromonas veronii, and aeromonas sobria.


Signs and Symptoms

Aeromonas can cause extraintestinal infections and intestinal infections in humans. The former includes sepsis, wounds, cholecystitis, ocular infection, articular infection, pulmonary infection, intraperitoneal infection, and systemic infection, mostly in immunocompromised patients, and the latter is mainly gastroenteritis.

Cutaneous manifestations are cellulitis, pustules, furuncles, gaseous gangrene, and gangrenous ecthyma.


Diagnosis

In immunocompromised patients with Liver cirrhosis, multiple myeloma, or rectal cancer, after ingestion of aquatic products, if diarrhea, fever, hemorrhage, vesicles, shock, and significant prolongation of both aPTT and PT are present, aeromonas infection should be considered. The definitive diagnosis is mainly based on the results of blood and blister fluid culture and histopathological findings.


Treatment

For extraintestinal infection, the third and fourth generation of cephalosporin, levofloxacin, amikacin, aztreonam, and imipenem can be used. For intestinal infection, chloramphenicol, fosfomycin, and levofloxacin are preferred.