Tropheryma

Tropheryma is a genus of bacteria in the family Tropherymataceae, phylum Actinobacteria. It comprises the species Tropheryma whipplei, the etiologic agent of Whipple disease in humans. The organisms are small, intracellular, Gram-positive‑like bacteria that are notoriously difficult to grow in routine culture.

Biology and ecology: Tropheryma whipplei is an obligate intracellular bacterium with a reduced genome. It resides primarily in macrophages of the intestinal lamina propria and other tissues. Cultivation in the laboratory is rare; detection relies on molecular methods such as PCR. The natural reservoir and transmission route are not fully established.

Clinical relevance: Whipple disease is a chronic, multisystem infection that can affect the small intestine, joints, heart, and central nervous system. Symptoms include weight loss, diarrhea, malabsorption, abdominal pain, and arthritis. If untreated, the disease can progress to severe malabsorption and organ involvement.

Diagnosis: Confirmation uses PCR detection of T. whipplei DNA in tissue or body fluids and histology showing PAS-positive macrophages in intestinal lamina propria. Culture is rarely successful; histology and molecular testing are primary diagnostic tools.

Treatment and prognosis: Therapy requires antibiotics with good intracellular penetration for a prolonged period. Common regimens begin with an intravenous antibiotic (for example ceftriaxone) followed by long-term oral therapy (such as trimethoprim-sulfamethoxazole or doxycycline) for about one year. Most patients improve with treatment, but relapse can occur.

Epidemiology and history: Whipple disease is rare and most often diagnosed in middle-aged men, particularly of European descent. The bacterium was identified in the 1990s and named Tropheryma whipplei; it is considered an obligate intracellular actinobacterium.