Streptococcus pneumoniae is a common cause of community-acquired infections. Pneumococci are estimated to cause up to 40% of cases of community-acquired pneumonia and 40,000 deaths annually in the United States.1,2 Presenting complaints with pneumococcal pneumonia usually include fever and pulmonary symptoms; however, gastrointestinal symptoms, including diarrhea, may also be present.3,4 We recently treated a patient with pneumococcal pneumonia who presented with a chief complaint of diarrhea. We then reviewed cases of pneumococcal bacteremia at our institution to determine the association of diarrhea with pneumococcal pneumonia.
A 41-year-old man with a history of non-insulin-requiring diabetes mellitus presented to the emergency department with a 3-day history of nausea, emesis, fever, chills, and 5 to 7 watery stools daily. He denied abdominal pain, melena, or hematochezia. He had not received any antibiotic therapy in the preceding 12 months. His temperature was 102°F and he was orthostatic. The results of physical examination were normal. The abdomen was soft and nontender on palpation and revealed normally active bowel sounds. The white blood cell count was 11,200 cells/μL. He was admitted with suspected gastroenteritis. Administration of intravenous ciprofloxacin (dosage, 400 mg every 12 hours) and intravenous fluids was begun. Chest radiograph revealed a left perihilar infiltrate. Stool test results were negative for leukocytes, blood, pathological bacteria or parasites, or the presence of Clostridium difficile toxin A or B. After 24 hours, the blood cultures were reported yielding Streptococcus pneumoniae. The antibiotic therapy was changed to levofloxacin (dosage, 500 mg orally once a day). During the next 48 hours, he had defervescence and his diarrhea resolved. He was discharged 5 days after admission and completed a 14-day course of treatment with complete recovery.
Cases of pneumococcal bacteremia occurring in our institution in 2002 were identified by reviewing the microbiology records and the hospital charts. Demographic details, medical history, symptomatology, initial laboratory and radiological findings, clinical course in the hospital, and outcome were noted. Diarrhea as a presenting symptom was considered present if the patient complained of having 3 or more watery stools daily before admission, or if 3 or more bowel movements were recorded for the first 24 hours of admission. Patients with a history of antibiotic use immediately before admission were excluded from the study.
Statistical analysis was performed using STATA statistical software (StataCorp LP, College Station, Tex).
Fifty-seven patients with pneumococcal bacteremia during the study period were identified. Fifty charts were available for review. The results are summarized in Table 1.
Twelve (24%) of 50 patients admitted with pneumococcal bacteremia had diarrhea (10 patients had a presenting history consistent with the diagnosis of diarrhea, whereas 2 patients were observed to have 3 or more watery stools during the first 24 hours of hospitalization). Of these 12 patients, 10 had associated respiratory symptoms, 7 had fever, and 6 had abdominal pain. In 2 of these patients, fever and abdominal pain were the chief complaints, and an infiltrate was incidentally found on routine admission chest radiograph.
In all patients, diarrhea was described as watery with no blood or mucus. The frequency of bowel movements varied from 3 to 12 per day. Abdominal examination in all patients was benign, except for 3 patients who had mild generalized abdominal tenderness that resolved within 48 hours. No effect was noticed on the basis of whether diarrhea was reported historically or observationally.
The only factor that was significantly associated with the presence of diarrhea was age. The mean age of patients with diarrhea was 43.1 years as compared with a mean age of 64.6 years among those who did not have diarrhea (P < 0.001; 95% confidence interval, 53.7-65). Of the 20 patients older than 60 years, only 1 patient reported diarrhea.
Diarrhea has not been commonly described as accompanying pneumococcal disease. In 1909, Osler used the term croupous colitis when discussing severe diarrhea accompanying pneumococcal infection.5 More recent reports have described diarrhea as a symptom in pneumococcal bacteremia.6-10 Others have used the terms pneumococcal enteritis 11 or pneumococcal colitis 12 when discussing diarrhea accompanied by pneumococcal infection.
As suggested by Brown et al,12 there seems to be 2 distinct mechanisms of pathogenesis on the basis of the presence or the absence of blood in the stool. Bloody diarrhea, which is relatively infrequent, seems caused by the direct invasion of the mesenteric lymph nodes and intestines by the bacterium, and subsequent symptoms suggest enteritis or colitis. Stool examination may reveal the presence of leukocytes. Patients without evidence of direct invasion of the intestinal wall by pneumococci usually have nonbloody watery diarrhea, and this seems to be the more common gastrointestinal presentation of pneumococcal bacteremia.6,11
Gastrointestinal symptoms have been previously reported to occur in approximately 10% of patients with pneumococcal infections.3,4 In our study, the incidence rate of diarrhea was 24%. This may reflect the inclusion of all patients with diarrhea, not just the patients in whom it was a major complaint. Thus, it is possible that diarrhea with pneumococcal infections may be more common than previously reported, although diarrhea is still infrequently the major presenting complaint with invasive pneumococcal infection.
In our patients, diarrhea preceded or coincided with the development of other symptoms and subsided within 48 hours of admission and antibiotic therapy. In none of our cases had bloody diarrhea or findings been suggestive of peritonitis. The pathogenesis of diarrhea in our cases is not clear. On the basis of the description of stool studies performed by Rio and McGovern10 and of the clinical presentations of our patients, the diarrhea may be secretory in nature. Further studies to evaluate other mechanisms, such as enterotoxin production, might be illuminating.
The only statistically significant finding in our study was the association of diarrhea with a younger age group. This is consistent with earlier reports.4,11 The cause for this possible predilection for younger patients is unknown, and further investigation might be revealing. Possible explanations could include infection caused by different strains of bacteria13 or an increased susceptibility to toxigenic diarrhea due to age-related receptor binding or effector responses.14
Although deaths occurred only in the group without reported diarrhea in our study, this was not found statistically significant. The mortality rate in bacteremic pneumococcal pneumonia has been reported to be higher in older adults.4 This seems to correlate with our finding that older patients were less likely to have diarrhea as a symptom of bacteremic pneumococcal pneumonia.
Diarrhea may be an infrequently recognized and reported symptom associated with invasive pneumococcal disease, especially pneumonia. Given that Streptococcus pneumoniae is a common cause of community-acquired infection, the awareness that it is occasionally a pathogen that may initially present with fever and diarrhea could lead to earlier diagnosis and appropriate treatment of a potentially severe or fatal infection rather than to treatment with empirical antibiotic therapy that may ultimately be found less than optimal (as what occurred in our case).
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