Helicobacter pylori

About the Microbe

Helicobacter pylori (H. pylori) is a pathogenic bacteria typically found within the upper gastrointestinal tract of humans, particularly the stomach
It is one of the most successful pathogens in humans – it occupies the gut of over half of the world’s population
Geographically, it is found around the globe, but is more prevalent in developing countries
H. pylori can cause a variety of diseases from gastritis to cancer. It was even the first formally recognized bacterial carcinogen!

Taxonomy

Domain: Bacteria
Kingdom: Eubacteria
Phylum: Proteobacteria
Class: Epsilonproteobacteria
Order: Campylobacterales
Family: Helicobacteraceae
Genus: Helicobacter
Species: Helicobacter pylori

Visualizing the Microbe

Gram Stain

This gram stain indicates that H. pylori is gram-negative.

H. pylori has two morphological shapes, spiral and coccoid. As seen in the figure above, Section A shows the mobile spiral shape and Section C shows the immobile coccoid form. They also tend to have 4-8 unipolar flagella.

SEM

A high-resolution Scanning Electron Microscope (SEM) called the Field Emission Gun Scanning Electron Microscope (FEG-SEM) was used.

TEM

TEM of H. pylori within cells

Confocal

Confocal microscopic study. Stained red are H. pylori

TEM

TEM of H. pylori

Diagnostic Tests

Blood Agar

The results should be negative for beta hemolysis, meaning that there should be no clearing of the medium shown by a strong yellow discoloration. However, Gideon did not specify whether H. pylori exhibited alpha hemolysis or gamma hemolysis.

MacConkey Agar

The results should show that H. pylori does not grow on MAC - seen as colorless colonies on the yellow plate. MAC includes bile salts to inhibit growth of gram-positive bacteria, and although H. Pylori is gram-negative, it is bile sensitive. So this may why the it tests negative.

Anaerobic Chamber

(Thioglycollate broth)

The results should show that H. pylori is microaerophilic, meaning that it requires oxygen but in low amounts. This oxygen requirement is characterized by growth in a thin layer just below the top oxygen-rich layer.

Phenol Red Broth

The results should show that H. pylori does not ferment glucose. This result is characterized by a red color in the tube.

Mannitol

The results should show that H. pylori has a negative result, indicated by a lack of yellow color on the plate. This means that H. pylori does not ferment mannitol sugar.

DNAse

On Gideon, no DNAse test result was found for H. pylori.

Generally, the test determines whether or not there is deoxyribonuclease activity. A positive result is shown by the formation of colorless-yellow zones, while a negative test is characterized by the absence of a colorless zone (stays green).

Gram Stain

The results should show that H. pylori is gram-negative, indicating that it has a thin peptidoglycan layer. A negative gram stain is characterized by its pink color.

SIM medium deep agar

The Sulfur-Indole-Motility (SIM) Agar Deeps test for indole production, sulfur reduction, and motility.

The results should show that H. pylori is motile. A positive motility test is characterized by the growth of bacteria away from the stab line as shown here.

The results should show that H. pylori does not produce indole. A negative indole test is characterized by the yellow color of the medium inside the tube as seen here.

The results should show that H. pylori does not reduce sulfur. A negative sulfur reduction test is characterized by its yellow color.

Oxidase

The results should show that H. pylori is positive for this test meaning that it produces oxidases. This positive test is characterized by its purple color on a disk or sheet.

Catalase

The results should show that H. pylori has a positive catalase test, indicating that it does have the catalase enzyme. This positive result is characterized by the formation of oxygen bubbles when hydrogen peroxide is added.

Disease & Treatment

Disease

H. pylori is a pathogen. Although the infection itself is not a disease, H. pylori is a key player in various gastrointestinal diseases such as chronic active gastritis, peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma.

Prevention

The primary method of infection is still yet to be determined, but it is thought to be through direct human-to-human transmission during childhood via either an oral-oral or fecal-oral route. And so, infection can be prevented through improving hygiene and sanitation, as well as antimicrobial treatment of those who carry it

Treatment

Antibiotics

Clarithromycin
Metronidazole
Secnidazole

Other treatments

The only other treatment would be different combinations of antibiotics along with PPIs or bismuth compounds. Of the many treatments studied, none have consistently reached eradication levels of 90-95%

References

Ahmed, Niyaz. “23 Years of the Discovery of Helicobacter Pylori: Is the Debate Over?” Annals of Clinical Microbiology and Antimicrobials 4 (October 31, 2005): 17. https://doi.org/10.1186/1476-0711-4-17.

Faghri, Jamshid, Farkhondeh Poursina, Sharareh Moghim, Hamid Zarkesh Esfahani, Bahram Nasr Esfahani, Hossein Fazeli, Nasrin Mirzaei, Azam Jamshidian, and Hajieh Ghasemian Safaei. “Morphological and Bactericidal Effects of Different Antibiotics on Helicobacter Pylori.” Jundishapur Journal of Microbiology 7, no. 1 (January 2014): e8704. https://doi.org/10.5812/jjm.8704.

Gu, Haiying. “Role of Flagella in the Pathogenesis of Helicobacter Pylori.” Current Microbiology 74, no. 7 (2017): 863–69. https://doi.org/10.1007/s00284-017-1256-4.

Haley, Kathryn Patricia, Eric Joshua Blanz, and Jennifer Angeline Gaddy. “High Resolution Electron Microscopy of the Helicobacter Pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability.” Journal of Visualized Experiments : JoVE, no. 93 (November 21, 2014). https://doi.org/10.3791/52122.

Kusters, Johannes G., Arnoud H. M. van Vliet, and Ernst J. Kuipers. “Pathogenesis of Helicobacter Pylori Infection.” Clinical Microbiology Reviews 19, no. 3 (July 1, 2006): 449–90. https://doi.org/10.1128/CMR.00054-05.

Marshall, B. J., and C. S. Goodwin. “Notes: Revised Nomenclature of Campylobacter Pyloridis.” International Journal of Systematic Bacteriology 37, no. 1 (January 1, 1987): 68–68. https://doi.org/10.1099/00207713-37-1-68.

Marshall, B. J., and J. R. Warren. “Unidentified Curved Bacilli in the Stomach of Patients with Gastritis and Peptic Ulceration.” Lancet (London, England) 1, no. 8390 (June 16, 1984): 1311–15. https://doi.org/10.1016/s0140-6736(84)91816-6.

Oh, Jung D., Sherif M. Karam, and Jeffrey I. Gordon. “Intracellular Helicobacter Pylori in Gastric Epithelial Progenitors.” Proceedings of the National Academy of Sciences 102, no. 14 (April 5, 2005): 5186–91. https://doi.org/10.1073/pnas.0407657102.

Shahamat, M., M. Alavi, J. E. M. Watts, J. M. Gonzalez, K. R. Sowers, D. W. Maeder, and F. T. Robb. “Development of Two PCR-Based Techniques for Detecting Helical and Coccoid Forms of Helicobacter Pylori.” Journal of Clinical Microbiology 42, no. 8 (August 2004): 3613–19. https://doi.org/10.1128/JCM.42.8.3613-3619.2004.

Tominaga, K., T. Watanabe, Y. Fujiwara, K. Higuchi, and T. Arakawa. “[Morphological investigation of H. pylori and its culture method].” Nihon Rinsho. Japanese Journal of Clinical Medicine 59, no. 2 (February 2001): 296–300.

About the Researcher

Hello! My name is Michelle Villate and I am a sophomore Microbiology and Cell Sciences major who plans to minor in Spanish and pathogenesis. Some of my hobbies include reading webcomics, singing, and learning Korean.

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