Aeromonas hydrophila infection

　　1. Etiology

　　Aeromonas hydrophila belongs to the family Vibrionaceae, is Gram-negative, has a single flagellum and motility, no capsule, and does not form spores. This bacterium is pathogenic to cold-blooded animals such as fish and frogs, as well as warm-blooded animals such as mice, guinea pigs, and rabbits. The virulence factors of this bacterium are mainly enterotoxins, including cholera toxin-like (CT) and heat-resistant enterotoxin-like Escherichia coli (LT). Some strains have invasive properties.

　　2. Pathogenesis

　　This bacterium is pathogenic to cold-blooded animals such as frogs and fish, as well as warm-blooded animals such as mice, guinea pigs, and rabbits. It can produce adhesins that are adhesive to intestinal epithelial cells, and can produce both heat-resistant and non-heat-resistant enterotoxins, as well as alpha and beta hemolysins, cytotoxicity, and other virulence factors. This bacterium can also produce some proteases that cause disease. Animal experiments show that mice infected with it can cause tissue damage, sepsis, endotoxin shock, and death.

　　1. Severe dehydration:It presents with fatigue, exhaustion, dizziness and blurred vision upon standing, even fainting, confusion of consciousness, some patients may have symptoms of insufficient blood supply to organ arteries such as chest pain, abdominal pain, common signs include poor skin elasticity, dry skin and mucous membranes, rapid and weak pulse, superficial veins collapse, cold extremities, and reduced urine output.

　　2. Pulmonary edema:It presents with severe dyspnea, sitting breathing, cyanosis, profuse sweating, paroxysmal cough with large amounts of white or pink frothy sputum, both lungs are filled with symmetrical wet rales, X-ray chest film shows butterfly-shaped blurred shadows in both lungs, and in the late stage, shock and even death may occur.

　　1. Acute gastroenteritis:The incubation period is about 1-2 days, symptoms are usually mild, with low fever or no fever, diarrhea presents as watery loose stools, abdominal pain without tenesmus, some patients may have severe diarrhea similar to cholera, children under 2 years old may show dysentery-like symptoms, most cases recover spontaneously within 2-5 days, and severe cases may last for 1-2 weeks.

　　2. Trauma infection:Infection occurs due to contact with river water and sludge through skin wounds, with mild cases only showing local ulcers and severe cases developing cellulitis.

　　3. Sepsis:When patients have serious chronic diseases, the bacterium can enter the blood from the wound or intestines, and Aeromonas hydrophila sepsis can be complicated with infectious endocarditis, necrotizing myositis, intraocular lesions, and migratory abscesses, etc.

　　4. Other infections:This bacterium can occasionally cause postoperative infection, urinary tract infection, bedsores, cholecystitis, peritonitis, pneumonia, meningitis, necrotizing myositis, and osteomyelitis, etc.

　　Aeromonas is mainly transmitted through water, so avoid contact with wastewater and drinking unboiled or disinfected water; wounds contaminated by natural water should be cleaned and disinfected in a timely manner; do not cough while swimming; since the bacteria also exist in fruits and vegetables, wash them before eating; if an epidemic occurs, change the water and toilets immediately to prevent the further spread of the pathogen. Avoid uncooked vegetables, meats, seafood, and unclean beverages. Drinking acidic beverages such as cola and orange juice can help in the recovery of health.

　　Routine stool examination can show a small number of white blood cells and red blood cells, and a few can show white blood cells throughout the field. The stool culture is positive for Aeromonas hydrophila.

　　In patients with pneumonia, an abnormal chest X-ray can be seen.

　　For patients with Aeromonas hydrophila infection, it is recommended to have a light and hygienic diet. For healthy adults, the daily fat intake should not be less than 40g, equivalent to 20g of oil, or half a pound of lean meat. Avoid spicy foods such as cigarettes, alcohol, coffee, strong tea, and various spicy seasonings such as scallions, ginger, garlic, chili, pepper, curry, etc. Reasonably match the diet.

　　1. Treatment

　　Gastroenteritis caused by Aeromonas hydrophila is usually self-limiting and generally does not require antibiotics. For severe diarrhea or patients with underlying diseases, or extraintestinal infections, gentamicin, or tobramycin, sulfamethoxazole/trimethoprim (sulfamethoxazole-trimethoprim), norfloxacin, and other drugs can be used. For focal infections, pus should be aspirated or incised and drained.

　　2. Prognosis

　　The prognosis is generally good, but it is more serious for those with serious chronic diseases that occur with extraintestinal lesions.