A water inhabiting gram-negative bacillus, Aeromonas hydrophila has long been
considered to be a saprophytic organism, nothing to do with human infections. But there
is an increasing evidence that this organism does cause human infections, some of
which are quite serious ones. Most of the infections have some relationship with water
contaminations. Many of the patients have some underlying conditions such as
hepatobiliary disease and various malignancies. During a 16 month period of time from
May 1977 to August 1578, the authors isolated A. hydrophila from 15 different patients.
Out of these 15 cases, an analysis of both clinical and laboratory data was made on 13
patients.
The results are as follows:
1) Most of the patients were 17- to 29-year-old males, a group who are prone to
suffer injury due to their activity.
2) Most of the cultures were isolated from wounds of extremities which is the site
easily contamined with water or soil. Specimens also included blood, bile, and peritoneal
fluid.
3) The patients had underlying conditions such as open wound, burn, carcinoma,
leukemia or hepatitis.
4) From 8 of the 13 patients other species of bacteria were also isolated. All of them
were gram-negative bacilli except 1 culture of S. aureus.
5) All of the isolates were susceptible to chloramphenicol, and gentamicin, but most of
them were resistant to ampicillin and to cephalothin by kirby-Bauer method.
6) Five out of the 13 patients died. The causes of death were thought to be:
septicemia, 4 and hemothorax, 1. Etiologic agent of 2 out of the 4 septicemias were
proven to be A. hydrophila, bacterilogically.
From this study it is concluded that A. hydrophila infection is not rare and the
infection include severe ones. To select proper antibiotics for the treatment, correct
identification of the infection was considered necessary.
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