Helicobacter pylori Lactose intolerance Bacterial overgrowth Exocrine Pancreatic Insufficiency




what is it?

It is the clinical manifestation occurring when there is an abnormal proliferation in the small intestine of normal bacterial flora of the lower digestive tract.

Usually there is normal bacterial flora which colonizes the colon in particular and helps to absorb nutrients and aids in the synthesis of some proteins

Overgrowth occurs when the bacteria in the colon invade determined parts of the small intestine.


Causes of bacterial overgrowth

Several etiological processes may alter the mechanisms which keep the number of these bacteria low:

  • Structural anomalies (congenital or surgical)
  • Disorders causing reduced gastric acidity
  • Reduction of the intestinal motility
  • Damaged or atrophic intestinal mucous



The clinical manifestations of the bacterial overgrowth syndrome are based on the increasing bacterial load which jeopardizes the normal functions of the upper gastrointestinal system.

The following symptoms, among others, stand out:

  • Abdominal distension
  • Weight loss
  • Steatorrhea (foul-smelling feces)
  • Watery diarrhea
  • Megaloblastic anemia
  • Neurological signs due to vitamin B12 deficiency


The early recognition and treatment of bacterial overgrowth syndrome must be targeted at preventing and reverting malabsorption processes.


Recommended treatment

The treatment frequently used in cases of bacterial overgrowth is usually broad-spectrum antibiotic therapy.

Treatment must always be that indicated by the prescribing physician.


Diagnosis and available tests

There are different types of diagnostic tests:


  • Breath Test to Diagnose Bacterial Overgrowth: is a non-invasive test and easy to perform breath. Measure is based on H2 and CH4 production in the breath after ingestion of lactose, for a certain time. The measurement of CH4 is done because about 30-40% of the population is not producing H2 (H2 in CH4 transform by methanogenic bacteria)
  • Collecting stools to check for the presence of steatorrhea
  • X-rays of the small intestine
  • Small intestine biopsy
  • Aspiration and culture of proximal jejunum secretion




  • Utilidad de la cuantificación del metano en aire espirado en la intolerancia a la lactosa y en el sobrecrecimiento bacteriano. Conchello Monleon R, Rodríguez Sanz ML, Ros Arnal I, Ros Mara L. Unidad de Gastroenterología y Nutrición Pediátrica. Hospital Miguel Servet. Zaragoza.
  • Bases físicas del test de hidrógeno. M. Fernández Bermejo. Médico Residente. Servicio de Medicina Digestiva. Hospital de la Princesa. Madrid.


Consenso Internacional

Upcoming Congress and Events

July 2020
29 30 1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31 1 2
No events

Latest news