In conclusion, H. pylori infection can be detected by a variety of methods. The simplest, least expensive noninvasive method is serologic testing. Unfortunately, positive serology can only presume current infection. Urea breath testing is also noninvasive and is positive only in the setting of current infection; it is more expensive than serology and results in low-level radiation exposure when 14C urea is used. Endoscopy with biopsy is invasive and relatively expensive; however, it is readily available and is frequently performed in the evaluation of the symptomatic individual. In such cases, rapid urease testing of biopsy material is simple and less expensive than histologic examination. Histology allows simultaneous evaluation of tissue injury and infection. Frequently, routine hematoxylin-and-eosin staining is sufficient to permit identification of the bacteria; when the results of this stain are inconclusive, special stains such as Giemsa or Warthin-Starry can be used. Finally, direct culture of the organism from gastric tissue is tedious and expensive; therefore, it should generally be reserved for protocol settings or for selected patients in whom antibiotic-resistant organisms are suspected.