Gordonia and Tsukamurella
Genera Gordonia and Tsukamurella are usually present in soil. They were earlier classified with Rhodococcus, because of their morphological similarities to it. These bacteria contain mycolic acid in their cell wall and are acid fast. Genus Gordonia organisms are rare opportunistic pathogens, which cause infec-tion in humans. They have been associated with pulmonary and cutaneous infections. Tsukamurella has been associated with catheter infections.
They are a group of bacteria that are commonly found in decaying vegetations. Thermoactinomyces, Saccharopolyspora, and Saccharomonospora are some important genera that have beenassociated with occasional human infections.
Tropheryma whippelii is an actinomycete known to causeWhipple’s disease. The bacterium is yet to be cultured. It is usually identified by molecular techniques. Whipple’s disease manifests as abdominal pain, diarrhea, fever, lymphadenopa-thy, pigmentation of the skin, and arthralgia. The condition is diagnosed by demonstration of the periodic acid–Schiff (PAS)-positive inclusion bodies found inside macrophages of the lamina propria of the small intestine. Detection of bacte-rial genome by PCR in intestinal tissue confirms the diagnosis.
Dermatophilus is an actinomycete that causes an exudative derma-titis affecting skin of the hands and feet. The condition is com-monly seen in individuals who are in close contact with infected animals or contaminated animal products. These pathogens are susceptible to commonly used antibiotics, such as penicillins and aminoglycosides. Dermatophilus is commonly found in the soil.
Oerskovia is an actinomycete that causes opportunistic infectionin humans. The bacterium is associated with cervicofacial infec-tions, catheter-associated bacteremia, traumatic endophthalmitis, CNS shunt infections, and infection in patients undergoing long-term peritoneal dialysis. They are usually resistant to antibiotics.