A new species of bacterium that causes leprosy has been identified through intensive genetic analysis of a pair of lethal infections, a research team reports in the December issue of the American Journal of Clinical Pathology.
Investigations by researchers at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences and the University of Texas M. D. Anderson Cancer Center Laboratory Medicine confirm a new, second species of leprosy mycobacterium that causes a rare, severe form of the disease called diffuse lepromatous leprosy (DLL). Cases of DLL occur mainly in Mexico, the Caribbean and countries in South America.
Dr. John Spencer became involved in the discovery in 2007 when a man showed up in a Phoenix health clinic covered with lesions and experiencing sensory loss in his feet. His doctors were mystified as to whether his condition might be caused by a bacterial infection, an autoimmune disease, or a type of cancer. His tissues began to break down, his organs began to fail and, after two weeks in the intensive care unit, the man died. His doctors suspected the man, who was originally from Mexico, died of complications from an aggressive, and often fatal, rare form of leprosy called diffuse lepromatous leprosy with Lucio's phenomenon.
"We received serum and biopsy specimens from a clinician at the clinic who wanted confirmation of their suspicions of leprosy," said Dr. Spencer, an Assistant Professor in the Department of Microbiology, Immunology and Pathology and researcher with the Mycobacteria Research Laboratories in the College of Veterinary Medicine and Biomedical Sciences. "Through serologic antigen recognition profiling and sequencing analysis of the DNA from this isolate at CSU and by Dr. Xiang Han, head of the Diagnostic Laboratory at the M. D. Anderson Cancer Center in Houston, it was determined that this mycobacterium was different. It showed a 2.1 percent difference in the 16S ribosomal gene from the bacterium known to cause leprosy, indicating a possible difference in species. It was a mycobacterium, but it wasn't M. leprae - the bacterium previously believed to cause this disease."
Funding for the project came from private philanthropy at M. D. Anderson Cancer Center, a National Cancer Institute grant to M. D. Anderson's DNA Core Facility, a National Institute of Allergy and Infectious Disease grant to Colorado State University and a College Research Council Award from Colorado State University.
Dr. Han and Dr. R. Geetha Nair, a physician with Maricopa Integrated Health System in Phoenix, are co-authors of the research along with Drs. Spencer and Wei Li of the Mycobacterial Research Laboratories; and Drs. Yiel-Hea Seo, Kurt Sizer, Taylor Schoberle and Gregory May of M. D. Anderson's Department of Laboratory Medicine.