Case ReportAeromonas hydrophila Infection

Chih-Kang Chou, MD

Chief Complain

• A 45 y/o male came to the ER with erythematous swelling of the right leg and multiple large hemorrhagic bullae.

Past & Personal History

• No job, smoking, drinking everyday• Hypertension• Type 2 diabetes mellitus• Liver cirrhosis with ascites• Atrial fibrillation• Admission to GI due to fever, chillness & diarrhea

on 100.8.19~8.21 • Bladder cancer - TUR-BT on 85.5.25• Anal fistulectomy on 92.9.8 and anal fistectomy on

92.11.24

Present Illness

• Right leg erythematous swelling and multiple bullae since one day ago.

• Fever, chillness and pain over right leg, so he came to our ER on 100.10.24.

• No known history of any sea food contact, trauma, or insect bites.

• Under the impression of right leg necrotizing fasciitis, he was admitted to our ward.

Course & Treatment

10/24 10/25

Course & Treatment

10/26 10/28

Course & Treatment

11/0111/07

Laboratory Data datadate

WBC Hb Platelet Neutrophil Lymphocyte Bun Cr Na K CRP NH3 Alb GOT GPT Bil(T/D) Osm Digoxin

10/24 4500 14.5 39000 88.2 10.8 18 2.3 139 2.6 29.5 101 50

10/25 5900 11.5 11000 83.8 7.4 99.4 88 1.8

10/26 8200 11.9 29000 91.4 4.8 45 2.8 139 3.4 83

10/27 8200 10.6 33000 91.3 7.3 67

10/28 8500 9.6 38000 86.9 9.3 43 2.3

10/31 9600 12.1 13000 81.8 15.2 55 1.9 162 3.4 24 2.2 123 85

11/01 10200 11.2 43000 165 3.6

11/02 10400 11.0 25000 162 25.13/18 373

11/04 8400 9.1 59000 41 1.8 162 3.3 37 2.1 0.61

11/07 6200 7.2 25000 73.4 23.0 156 3.6 57.5 2.0 94

Bacterial Culture

• Wound culture: Aeromonas hydrophila

• Blood culture: Aeromonas hydrophila/ caviae

Aeromonas hydrophila (親水性產氣單胞桿菌 )

• Found in all freshwater environments as well as brackish, chlorinated, and unchlorinated water.

• Both a gram-negative rod and a facultative anaerobe.• Can grow in temperatures as low as 4oC. These bacteria are motile

by a polar flagella.• Very toxic to many organisms. When it enters the body of its victim,

it travels through the bloodstream to the first available organ. • Produces Aerolysin Cytotoxic Enterotoxin (ACT), a toxin that can

cause tissue damage.• Considered to be opportunistic pathogens, meaning they rarely

infect healthy individuals.• Considered a major fish and amphibian pathogen, and its

pathogenicity in humans has been recognized for decades.

Fish and Amphibians

• Associated with diseases mainly found in fish and amphibians, because these organisms live in aquatic environments.

• It is linked to a disease found in frogs called red leg, which causes internal, sometimes fatal hemorrhage.

• When infected, fish develop ulcers, tail rot, fin rot, and hemorrhagic septicemia.

• Hemorrhagic septicemia causes lesions that lead to scale shedding, hemorrhages in the gills and anal area, ulcers, exophthalmia, and abdominal swelling.

Fish and Amphibians

Sites of infection in humans

• GI: gastroenteritis/dysentery (children may be severe, adults less so or chronic), peritonitis (rare).

• Skin/soft tissue infection: – Cellulitis (may be fulminant with necrotizing features).

– Necrotizing fascitiis and mynoecrosis also may occur.

• Sepsis: bacteremia often associated with malignancy, hepatobiliary disease such as cirrhosis, less commonly with diabetes.

• Bone: osteomyelitis, septic arthritis

• CNS: meningitis (rare)

• Cardiac: endocarditis (rare)

Gastroenteritis

• Through oral contact with contaminated water, food, soil, feces, and/or ingestion of contaminated fish or reptiles.

• Two types of gastroenteritis. 1. Similar to cholera, which causes rice-water diarrhea.

2. Dysenteric gastroenteritis, which causes loose stools filled with blood and mucus. Dysenteric gastroenteritis is the most severe out of the two types, and can last for multiple weeks.

Soft tissue infection

• Commonly acquired through an open wound that is exposed to contaminated water.

• Can cause severe skin/soft tissue infection and sepsis, often in the immunocompromised.

• Risk factors for severe infection: immunocompromise, diabetes, hepatobiliary disease (cirrhosis). 

• Cellulitis can be severe and spread rapidly, often within hours following exposure.

• Infection into deeper tissues may cause necrotizing fasciitis or myonecrosis. Bullae and ecythma gangrenosum may be observed.

Antibiotics treatment

• Resistant to penicillin, ampicillin, carbenicillin, and ticarcillin.

• Susceptible to broad-spectrum cephalosporins, aminoglycosides, carbapenems, chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, and quinolones.

Necrotizing Fasciitis (NF)• An insidiously advancing soft tissue infection characterized by

widespread fascial necrosis.• Increased risk in diabetics, elderly, infants, those with liver disease, or

those taking immunosuppressive drugs such as chemotherapy for cancer.• 初期與蜂窩組織炎不易區別，皮膚顯現

– 紅腫有大水泡，血色水泡– 血水分泌物，然後化膿– 皮膚由紅轉為灰白，然後壞死

• Classification– Type I, or polymicrobial, after trauma or surgery.

• A variant of NF type I is saltwater NF, a Vibrio species.

– Type II, or group A Streptococcal.– Type III gas gangrene, or clostridial myonecrosis.

Fournier’s Gangrene

Vibrio Vulnificus

Vibrio Vulnificus

Streptococcal Necrotizing Fasciitis

Necrotizing Fasciitis with Mycotic Aneurysm Infected with Salmonella

Treatment of NF

• Aggressive resuscitation to maintain hemodynamic stability.

• Broad-spectrum antibiotics to cover aerobic gram-positive & gram-negative organisms and anaerobes.

• Surgical debridement, early and aggressive, multiple and extensive.

• Following fluid resuscitation and nutritional support.

• Wound care, & wound reconstruction.

• Hyperbaric oxygen (HBO)

Conclusion

• Aeromonas hydrophila infection is frequently the cause of necrotizing fasciitis in patients with suppressed immune systems, diabetes, burns, and trauma in an aquatic setting.

• These patients require aggressive antimicrobial therapy and debridement and the mortality rate is high.

• Individuals that fail to respond to these treatment measures may require amputation.