Aeromonas caviae and Aeromonas veronii Causing Acute Cholecystitis

To the Editor:

Aeromonas species are widely reported to cause infections, including biliary sepsis [1]. Aeromonas hydrophila causes most cases of biliary sepsis, commonly on a background of immunosuppression [2]. Aeromonas caviae is a rare cause of biliary sepsis. There are five reports of acute cholecystitis (AC) caused by Aeromonas caviae, only one of which in an immunocompetent patient [3]. We report an immunocompetent male patient with AC managed by percutaneous cholecystostomy in whom Aeromonas caviae was isolated from bile. At the time of interval cholecystectomy six weeks later, Aeromonas veronii was isolated from bile. This is the only report with bile fluid isolation of two different Aeromonas species at two separate time points in the same patient.

A 76-year-old male with hypertension, hyperlipidemia, and diabetes mellitus was admitted for generalized abdominal pain of one-day duration. He had tachycardia, altered mental state, and type 2 myocardial infarction. Abdominal computed tomography (CT) scan revealed an edematous gallbladder. Because of his elevated bilirubin, a magnetic resonance cholangiopancreatography scan was done that established a diagnosis of cholecystitis and normal bile duct. A percutaneous cholecystostomy was performed. Bile grew Streptococcus gallolyticus, Escherichia coli, and Aeromonas caviae. Microbial sensitivity results and antibiotic stewardship guided antibiotic therapy. Elective laparoscopic cholecystectomy performed six weeks later revealed an empyema and Aeromonas veronii was isolated from intra-operative bile specimen. A further course of antibiotic agents was prescribed for seven days. Post-operative recovery was uncomplicated.

The four major species of Aeromonas include Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Aeromonas sobria [1]. Aeromonas species are found in fresh water, sewage, and soil. A PubMed search on October 31, 2020 revealed five cases of AC caused by Aeromonas. Aeromonas infections are more common in immunocompromised hosts, and Aeromonas caviae is associated with extra-intestinal infections [1]. In immunocompetent patients, only one report of Aeromonas caviae causing AC has been reported [3]. Our patient was not immunocompromised. In our patient, Aeromonas caviae and Aeromonas veronii were isolated from bile and not all reports clarify whether the bacteria was isolated from blood or bile.

Acute cholecystitis is caused by gram-negative bacteria and is usually treated with antibiotic agents and early cholecystectomy [4]. Antibioitic stewardship guided by local antibiogram not only improves clinical outcomes, but also reduces risk of drug resistance. Drug resistance is less commonly noted in Aeromonas caviae (39.6%) and Aeromonas veronii (16.7%) compared with other Aeromonas species [1]. In our patient, Aeromonas caviae and Aeromonas veronii were resistant to ampicillin, amoxicillin-clavulanate, and cephalosporins. We performed percutaneous cholecystostomy because in patients with severe AC, the priority is to restore organ function. In a local study reporting 103 patients with AC treated by percutaneous cholecystostomy, Yeo et al. [5] reported that 41% of patients eventually underwent cholecystectomy. In our patient, empyema was noted at interval cholecystectomy and bile culture grew Aeromonas veronii, which is a dual infection not reported previously. Our patient did not report any injury leading to skin breach and we are unsure of the source and portal of infection. In conclusion, AC with Aeromonas cavaie and Aeromonas veronii is rare in immunocompetent adults, and standard management principles achieve good clinical outcomes.