Granulobacter bethesdensis
Loraine Johnson

Chronic granulomatous disease (CGD) is a rare and inheritable disease that weakens the immune system due to a defect in the phagocyte NADPH oxidase, an enzyme used by neutrophils to generate hydrogen peroxide that kills fungi and bacteria. Approximately one person in 250,000 is affected with this immunosuppressant disease. This disease leaves patients highly susceptible to recurring infections. These patients will arrive at hospitals with a number of syndromes such as pneumonia or inflamed lymph nodes and typically they are treated with a broad spectrum anti-bacterial and anti-fungal therapy. Dr. Steven M. Holland of the National Institute of Allergy and Infectious Disease (NIAID) said that about 50% of the infections found in patients with CGD could not be diagnosed. These patients were treated surgically and or with broad spectrum drugs and many of the infections were never treated successfully.

In July, 2003, a 39 year old man with CGD was referred to the National Institute of Health after three months of recurring fever, night sweats, chills and significant weight loss. Initially he was treated with the usual broad spectrum antimicrobials to which there was little relief but, soon thereafter his lymph nodes became enlarged and his signs and symptoms persisted. Dr. David E. Greenberg of NIAID biopsied and removed several lymph nodes which, revealed widespread infection. A few of the tests that were performed confirmed the presence of a bacterium but they did not know what type. Greenberg and his colleagues utilized genetic sequencing to determine what kind of bacterium they were dealing with. The question at hand was whether it was a common microbe that had simply evaded detection or whether they had found an entirely new human pathogen.

The sequencing revealed that the bacterium was a member of the Acetobacteraceae family. This family of bacterium is actually quite common in the environment and is found in fruits, fermented food, plants, soil, water and some members of this family are used industrially to make vinegar. What is unusual is that no members of this family have ever been known to cause human disease. NIH Director Elias A. Zerhouni says “The discovery of new bacteria is not uncommon, but discovering an organism that causes human illness is certainly unique.” It was believed that most disease causing agents had been found but this finding suggests otherwise.

The bacterium was isolated in a charcoal-yeast extract medium from the lymph nodes of the 39 year old man with CGD. The 16S rRNA gene was sequenced and compared to sequences in GenBank revealing that Granulobacter bethesdensis is a new genus and species in the Acetobacteraceae family. G. bethesdensis is a mesophilic nonmotile coccobacillus that is catalase-positive. This new bacterium is named for where it was discovered, NIH, Bethesda, Md. It is important to note that this organism may be responsible for infections in patients with other immunosuppressant diseases and so, it is a great concern for people with CGD and for those that may have any of the 80 primary immune deficiencies.

References

Fredricks, David and Lalita Ramakrishnan. “The Acetobacteraceae: Extending the Spectrum of Human Pathogens”. April 2006. <http://www.plospathogens.org>.

Genome Project: Granulobacter bethesdensis. National Center for Biotechnology Information. 16 Jan 2007. <http://www.ncbi.nlm.nih.gov/>.

Granulobacter bethesdensis. Kyoto Encyclopedia of Genes and Genomes. 20 Feb 2007.
<http://www.genome.jp/>.

Maugh, Thomas H. “New Bacteria Discovery Clears Up Mystery”. 15 Apr 2006.
<http://www.rense.com/>.

Novel Gram-negative Bacillus. June 2006. Medscape. <http://www.medscape.com/>.

United States. Department of Health and Human Services. National Institute of Health. Researchers Discover New Disease-Causing Bacterium in Patients with Rare Immune Disorder. 13 April 2006. <http://www.nih.gov/>.

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.

 

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