Introduction

Candida overgrowth causing diarrhea is rare. There are only a few reported cases of individuals with underlying malignancy, severe immunocompromise, on immunosuppressive therapy or on recent antibiotic therapy who have had Candida-induced diarrhea. It is unclear if individuals without these recognized conditions can have an overgrowth of Candida species in the small bowel resulting in diarrhea. This report is a rare case of an immunocompetent individual with noninvasive small-bowel candidiasis presenting with diarrhea. We also offer a review of the literature.

Case report

A 61-year-old man with a past medical history significant for hepatitis C, hypertension, insulin-dependent diabetes, and chronic diarrhea presented to George Washington University Hospital complaining of one week of worsening diarrhea and severe bilateral lower-extremity pain. The patient reported that he had a one-year history of chronic diarrhea. During the week before admission, the diarrhea worsened in frequency and severity. The diarrhea was associated with crampy abdominal pain, was watery in nature, and was without blood or mucous. The patient denied any recent antibiotic or steroid use, hospitalizations, travel, or sick contacts. Previous evaluation for chronic diarrhea included stool culture with evaluation for ova/parasites, C. difficile analysis, and sudan stain. Prior celiac serologic assessment was negative, and a previous colonoscopy was normal.

Upon admission, a CBC and blood chemistry panel were both normal. Additional stool studies were performed and were negative for leukocytes, culture, ova/parasites, and C. difficile toxin. Quantitative fecal fat analysis was within normal limits. Serologic markers for celiac disease, including IgA antibodies, TTG, and serum trypsin, were also within normal limits. A CT scan of the abdomen, performed for evaluation of persistent abdominal pain, was normal. A colonoscopy with biopsy was performed to evaluate for any new inflammatory process, but there were no significant findings. An upper endoscopy revealed normal mucosa, however, the small bowel aspirates were positive for>100,000 colonies of Candida albicans. The patient was started on nystatin 1 million units three times a day. After four days the patient reported that he was having only one to two bowel movements per day and that the stool was less watery. The patient also reported a significant decrease in the quantity of lower abdominal pain. Following a full week of antifungal therapy, the patient had complete resolution of his diarrhea and abdominal pain.

Discussion

It is not uncommon to isolate Candida from stool cultures of asymptomatic individuals without underlying disease, and its presence in feces is usually considered insignificant. We present an unusual case of an immunocompetent individual having diarrhea and abdominal cramping because of intestinal overgrowth of Candida. A search of the literature revealed only six similarly reported cases. These cases, reported in 1976 by Kane et al. [1], described six otherwise healthy people who had at least three months of watery diarrhea and abdominal cramping. All of the cases had stool specimens containing Candida, and all of the patients had resolution of diarrhea following a four-day course of nystatin [1].

Most reported cases of Candida-induced diarrhea describe either malnourished patients with a disorder of the secretory IgA immune system or patients who are critically ill [2]. Joshi et al. [3] reported a case in 1981 of esophageal, duodenal, and jejunal candidiasis in a patient who received a renal transplant. The patient had received immunosuppressive therapy of prednisone and azathioprine, which is a well-known favorable factor for fungal infections. In 1976 Strober et al. [4] reported on a patient with a disorder of the secretory IgA immune system who had recurrent bouts of Candida-associated diarrhea.

Other factors leading to the transition of Candida from a saprophytic organism to a pathogenic one are likely related to conditions favoring the proliferation and invasion of yeast. For example, alterations of normal flora by antibiotics can induce Candida overgrowth. Organisms such as enterobacteriaceae and lactobacilli are inhibitory to the growth of Candida, and alteration of the normal gut flora by antibiotics can often promote Candida proliferation [5]. Use of tetracycline antibiotics not only changes the intestinal environment but also promotes Candida growth by directly inhibiting the phagocytosis of yeast by intestinal neutrophils [6]. Other conditions favoring Candida proliferation include steroid use, decreased mucosal resistance, leukopenia and prolonged hospitalization [2]. Gupta et al. [2] reported ten cases of severe diarrhea associated with intestinal Candida overgrowth. All ten had prolonged hospital stays and were being treated with multiple antibiotics or chemotherapeutic agents. The use of oral contraceptives, which alter the glycogen storage content of epithelial cells and can lead to a weakened mucosal barrier, has also been implicated as a cause of Candida-associated diarrhea [3].

The mechanism by which Candida overgrowth causes diarrhea is unknown. One theory is that Candida species can depress lactase activity and thus may lead to lactose intolerance [7]. Another theory is that Candidal colonization inhibits jejunal absorption and stimulates a net secretion of water, sodium, and potassium into the lumen [8, 9]. A final theory is that Candida produces an endotoxin-like substance, causing a toxin-mediated secretory diarrhea [3].

The clinical presentation of Candida-induced diarrhea is similar to the presentation of other types of intestinal infection. In all of the reported cases, the patient has several soft to watery bowel movements daily. Physical exam is normal except for the presence of diffuse, crampy abdominal pain. Fever, nausea, and vomiting usually do not occur, and blood counts and chemistry values are often normal. The diarrhea may be distinguished from a viral etiology by its protracted course, the presence of yeast in the small-bowel aspirate or stool, and the response to oral antifungals.

We have presented a patient with chronic diarrhea and associated lower abdominal pain with a small bowel aspirate positive for Candida albicans. It is possible that the patient may have had an underlying immunodeficiency or normal immunosenescence because of his age. However, it would have been unusual for the patient to have no other symptoms, history, or signs of infection. The positive response and resolution of symptoms soon after the initiation of antifungal treatment suggests a mycologic etiology. Additional research is needed to understand the pathophysiology of Candida-induced diarrhea. While most cases involve patients who are immunocompromised, our case demonstrates that Candida overgrowth can occur in immunocompetent individuals.