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In the megaesophagus of Chagas' disease, chronic esophagitis is caused by stasis of swallowed food and saliva. In this environment, the overgrowth of aerobic and anaerobic bacteria, including nitrate-reducing bacteria, is observed. The reduction of nitrate into nitrite by the action of these bacteria has been associated with the formation of volatile nitrosamines in different situations of gastric bacterial overgrowth. We have hypothesized that this phenomenon could occur in the esophageal lumen of patients with megaesophagus. To evaluate the concentration of nitrite, the presence of volatile nitrosamines and the concentration of nitrate-reducing bacteria in the esophageal lumen of patients with non-advanced megaesophagus of Chagas' disease and in a group of patients without esophageal disease. Fifteen patients with non-advanced megaesophagus [megaesophagus group (MG)] and 15 patients without any esophageal disease [control group (CG)] were studied. Saliva samples were taken for nitrate and nitrite quantitative determination and esophageal stasis liquid samples were taken for nitrate and nitrite quantitative determination, volatile nitrosamines qualitative determination and reductive bacteria quantitative determination. MG and CG were equivalent in nitrate and nitrite saliva concentration and in nitrate esophageal concentration. Significant difference was found in nitrite (p = 0.003) and reductive bacteria concentration (p < 0.0001), both higher in MG. Volatile nitrosamines were identified in three MG patients and in none of the CG patients, but this was not significant (p = 0.113). There is a higher concentration of reductive bacteria in MG, responsible for the rise in nitrite concentration at the esophageal lumen and, eventually, for the formation of volatile nitrosamines.

Bacterial overgrowth in the esophageal lumen in patients with megaesophagus can be the cause of recurring pulmonary infections, infectious complications due to surgical or endoscopic procedures, and the development of dysplasia of the esophageal mucosa and cancer. Despite this, esophageal microbiota in the megaesophagus have never been studied. The aim of this study was to analyze qualitatively and quantitatively the microbiota in chagasic megaesophagus in comparison to the normal esophagus. Twenty-five patients (10 men and 15 women), ranging in age from 24 to 74 years (mean years), were prospectively studied from March to September 2000. Fifteen patients with chagasic megaesophagus were divided into three subgroups (n = 5 patients in each) according to the grade of esophageal dilation: MG1 = megaesophagus grade I; MG2 = megaesophagus grade II; and MG3 = megaesophagus grade III. Another group of 10 patients without esophageal disease served as a control group. Samples were collected using a method especially developed to avoid contamination with microorganisms of the oral cavity and oropharynx. In the control group, 40% of the cultures were positive with the genus Streptococcus predominating and concentrations varying from 10(1) to 10(2) colony-forming units/ml. In the megaesophagus group, 93.3% of the cultures were positive, with great variability in the bacteria and a predominance of various aerobic gram-positive bacteria (Streptococcus was most common) and anaerobic bacteria (Veillonella was most frequent) in concentrations that ranged from 10(1) to 10(5) colony-forming units/ml. The bacterial concentrations were generally more elevated in MG3 patients in comparison to MG1 and MG2 patients and the control group (P < 0.05). It was concluded that patients with megaesophagus have a variety of microbiota consisting mostly of aerobic gram-positive and anaerobic bacteria, in concentrations that varied according to the degree of esophageal dilation., (Copyright 2002 The Society for Surgery of the Alimentary Tract, Inc.)