Septicemia due to Aeromonas hydrophila in a Pregnant Woman: A Case Report and Review of the Literature

Background: In the late 1960s, the first isolates of Aeromonas were recovered from human specimens. Presently, there is sufficient evidence to suggest that the different isolates of the genus Aeromonas are human pathogens. The most frequent site of infection is the digestive tract, although extraintestinal infection also occurs. In those cases involving septicemia, most infections occur in individuals with underlying diseases. This report presents the case of a pregnant woman with no underlying disease or signs of immunodeficiency who developed A. hydrophila septicemia at 24 weeks gestation. Case: A 20-year-old pregnant woman was admitted with a history of 10 days of fever, chills, and diaphoresis. Three days before her hospitalization, she noted jaundice and choluria. Her liver was enlarged and her liver function tests were abnormal, with a moderate elevation of serum aminotransferases and direct serum bilirubin and a high serum alkaline phosphatase. Her blood and bone-marrow cultures revealed A. hydropkila. She was treated with parenteral ceftriaxone. She experienced a complete remission of her symptoms and laboratory abnormalities after therapy. The remainder of the pregnancy was normal. At 39.2 weeks gestation, she delivered a healthy male infant. Conclusion: An association was noted between pregnancy and A. hydrophila septicemia in a woman without immunodeficiency or underlying disease, possibly indicating another infectious complication in pregnancy.

embers of the genus Aeromonas are gram-negative rods that belong to the family Vibrionaceae. They are oxidase-positive, facultative anaerobes with large zones of hemolysis around colonies on blood agar that ferment carbohydrates. 'z Aeromonas was isolated in human feces for the first time in 1937. Not until 1980 was it recognized as a pathogenic bacteria causing gastrointestinal diseases in human beings. The spectrum of intestinal diseases caused by Aeromonas ranges from acute, self-limited gastroenteritis of moderate intensity to chronic diarrhea that can persist for weeks or months. With lesser frequency, aeromonads have been associated with extra-intestinal infections, resulting in peritonitis, osteomyelitis, skin and softtissue infections, meningitis, endocarditis, and septicemia.I, [4][5][6] It has been suggested that patients who have immunosuppression or malignant diseases are more easily infected with aeromonads, although normal, healthy individuals may become infected as well.
In cases ofAeromonas septicemia, many of the infec-tions occur in individuals with neoplastic diseases, while septicemia in patients without predisposing conditions is rare.
A case of a pregnant woman without previous or concomitant disease, who developed an A. hydrophila septicemia at 24 weeks gestation is presented. A brief review of the literature on the association and incidence of Aeromonas infections and pregnancy is also presented.

CASE REPORT
A 20-year-old primigravida at 24 weeks of gestation was admitted to the National Institute of Perinatology with a history of 10 days of fever, chills, diaphoresis, asthenia, and adynamia. Three days before her hospitalization, she noted choluria and jaundice and complained of a cough and pharyngeal pain. On her admission, she was agitated, and tachycardic with mental obtundation. She had dry oral mucosa, decreased skin turgor, and generalized jaundice.
Her temperature was 38.5C. Her examination revealed right upper-quandrant pain, an enlarged liver, and a pregnant uterus. A complete blood count revealed slight normochromic/normocytic anemia and a leukocyte count of 5,300/I,1 with 22% bands. Her liver function tests were abnormal, with a moderate elevation of serum aminotransferases (aspartate aminotransferase of 66 u/1 and alanine aminotransferase of 52 u/l), an increase in direct serum bilirubin to 3.8 mg/dl, and a high serum alkaline phosphatase of 1,628 u/1. An abdominal ultrasound showed a normal biliary tract and an enlarged liver.
A viable fetus with a gestational age of 18-20 weeks was observed. The discrepancy between the patient's reported gestational age and the ultrasound finding was attributable to her irrregular menstrual cycle, making the true gestational age of the fetus uncertain.
The clinical picture was compatible with a sepsis syndrome. She was treated with parenteral ceftriaxone. On the 4th day of hospitalization, she became less febrile, and her blood and bone-marrow cultures revealed A. hydrophila. The bone-marrow culture was initially done to rule out typhoid fever. A stool culture was not done because the patient had no gastrointestinal symptoms. She experienced a complete remission of the signs and symptoms of sepsis and a normalization of her laboratory tests after therapy.
The serologic studies against hepatitis virus A, B, and C as well as anti-HIV were negative. The A. hydrophila isolated was resistant to gentamycin.
The remainder of her pregnancy was normal. At 39.2 weeks, she reentered the hospital and delivered a healthy male. The histopathologic study of the placenta was normal.

DISCUSSION
In the last 2 decades, the genus Aeromonas has been increasingly recognized as a human pathogen. In the early 1980s, on the basis of biochemical characteristics, 4 phenotypes of Aeromonas were recognized: A. hydrophila, A. sobria, A. caviae, and A. vetonil Because of the marked differences in the polynucleotide sequences in each of these phenotypes, a new classification based on DNA-DNA reassociation kinetics was proposed: the hybridization group (HG). For most institutions, the identification of Aeromonas isolates within the HG is impractical because of the technical time required and the costs of reagents and equipment. A feasible alternative is to identify aeromonads within the phenotypes.
Initially, aeromonads were identified as pathogenic in cold-blooded animals. In 1968, von Graevenitz and Mensch 1 reported the first series of Aeromonas isolates from human specimens. Of the 30 cases reported, 14 were of gastrointestinal origin. In 19 patients, the isolates were mixed with other bacteria. In 2 of them, both with hepatic cirrhosis, the isolation was from a blood culture. 1 Presently, there appears to be a consensus that aeromonads cause gastrointestinal disease. In addition to their pathogenic role, aeromonads have been found in the feces of so-called asymptomatic carriers.
In 1988, the State of California established that an infection with Aeromonas was an obligatory reportable disease. 1 In California, the annual incidence of Aeromonas infection was 10.6 cases/million inhabitants. In 1 year, Aeromonas was isolated in the feces of 178 patients; in 19, from soft-tissue infections; in 11, from blood cultures; in 5, from bile; and in 12, from various other specimens including urine, sputum, eye, and placenta. Ninety percent of the patients with Aeromonas isolated from their feces also had gastrointestinal symptoms. 1 After the digestive tract, the most frequent sites of aeromonad infections are the skin and soft tissues. The majority of these cases are associated with trauma in aquatic environments and contami-nation of injuries, lz-1 The spectrum of these infections include cellulitis, gas gangrene, myonecrosis, fulminant necrotizing infections, and osteomyelitis. Voss et al. 15 recently reported a series of 28 patients with musculoskeletal and soft-tissue Aeromonas infections, 23 (82%) of whom had acute open or penetrating injuries. In 13 of these, the initial trauma occurred in lake or river water. In the pathogenesis of this type of infection, it has been suggested that aeromonads produce hemolysins and cytotoxins that serve as virulent factors. These intracellular products may facilitate the tissue damage as well as muscle lesions. 16 Septicemia due to Aeromonas is infrequent. Most cases are sporadic and community acquired, although nosocomial cases have been described. 4'7'8 A. hydrophila and A. sobria have been implicated as the species most frequently associated with septicemia. 8'7'8 Aeromoas septicemia is most likely to occur in patients who have immunocompromised or some underlying disease such as a malignancy, liver cirrhosis, or diabetes mellitus and perhaps in the elderly as a result of a decline in immune functions. 7,8,7,8 Few cases of septicemia caused by Aeromonas have been described in patients without immunodeficiency. In the patient presented here, there was no underlying disease or history of immunodeficiency. In a series of 24 patients with Aeromonas bacteremia, only I was reported as not having a neoplastic disease. In another study of 16 patients with septicemia, 8 had hematologic disorders and 6 had severe underlying illnesses, while only 2 were apparently healthy. Thirteen patients with Aeromonas septicemia were reported from Australia in the years between 1983 and 1987. Chronic illnesses were present in 10 of these. Of the 3 remaining patients, 2 presented with cholangitis and the third, an otherwise healthy 20-year-old male, developed fever 4 days after an umcomplicated tonsilectomy. 1 In all cases reported in the literature, the mortality was significanly associated with the severity of the underlying disease. In the epidemiologic studies of Aeromonas infection reported from the State In these patients, an infection of the intrahepatic biliary tract was the origin of the septicemia. The moderate alterations in the liver function tests presented by our patient and the correction of these laboratory abnormalities after therapy suggest that the liver function abnormalities resulted from cholestasis secondary to sepsis.
In a review of the medical literature using MED-LINE CD-ROMM and Index Medicus from 1970 to 1994, we found no report of an association between Aeromonas septicemia and pregnancy. However, there were reports of the isolation of Aeromonas in septic abortion material and placenta. 1 In an abstract of an infectious diseases conference just case was reported of a pregnant woman who died as a result of a septic abortion in whom A. hydrophila was isolated from a blood culture. 9 The vulnerability of pregnant women to infections depends on many host factors, including past and present immunologic status, hormonal and hematologic changes occurring during pregnancy, and perhaps dietary habits. Some altered immune responses during pregnancy involve a decrease in specific antibody titers, a decrease in total T-lymphocytes, and a decrease in helper-suppressor ratios, as well as a decrease in the chemotactic and phagocytic properties of granulocytes, z In the case reported here, the origin of the sepsis is still unknown. In the majority of the septicemia cases we reviewed, the origin was considered to be endogenous, principally from the patient's digestive tract.
Aeromonas species are usually susceptible in vitro to third-generation cephalosporins, quinolones, and aminoglycosides, as well to the new [3-1actam antibiotics such as aztreonam and imipenem, z