Nitrate- and nitrite-reducing bacteria in the achlorhydric stomach

Area of Science:

• Microbiology
• Gastroenterology
• Bacterial Metabolism

Background:

• Achlorhydria, a condition of reduced stomach acid, alters the gastric environment, potentially affecting microbial composition and function.
• The role of gastric bacteria in nitrate and nitrite metabolism within the unique pH of an achlorhydric stomach is not fully understood.

Purpose of the Study:

• To investigate the microbial composition of gastric juice in achlorhydric patients.
• To determine the nitrate and nitrite reducing capabilities of commonly isolated gastric bacteria.
• To predict the potential for nitrite accumulation in the achlorhydric stomach based on bacterial activity.

Main Methods:

• Aerobic and anaerobic culture techniques were used to analyze gastric juice from eight achlorhydric patients.
• Bacterial isolates were identified, and their nitrate and nitrite reduction potentials were measured.
• Mixed cultures were studied to observe transient nitrite accumulation dynamics.

Main Results:

• Sixteen bacterial genera were isolated, with Streptococci, Neisseriae, and Haemophili found in all patients.
• Veillonellae, Haemophili, Staphylococci, Corynebacteria, Lactobacilli, Flavobacteria, and Fusobacteria reduced both nitrate and nitrite.
• Haemophili and Veillonellae exhibited rapid nitrate reduction, potentially leading to nitrite accumulation, while Streptococci and Neisseriae primarily reduced nitrite.

Conclusions:

• Specific gastric bacteria, particularly Haemophili and Veillonellae, may contribute to nitrite accumulation in achlorhydric stomachs.
• The balance of bacterial nitrate and nitrite metabolism influences nitrite levels in the achlorhydric gastric environment.
• Understanding these microbial dynamics is crucial for assessing the health implications of altered gastric conditions.