Nocardia is a genus of aerobic actinomycetes responsible for localized or disseminated infections in animals and humans. The genus is named after Edmond Nocard, who in 1888 described the isolation of an aerobic actinomycete from cattle with bovine farcy. The…
Revised March 30, 2021 Overview The recent advances in mycobacterial culture techniques and the increasing utility of modern molecular techniques for identification of previously unidentified organisms have produced a major resurgence of interest in disease caused by the nontuberculous mycobacteria…
Mycobacterium avium complex (MAC) is the most common of all the nontuberculous mycobacteria (NTM) to cause human infection and pulmonary infection. MAC contains genetically diverse strains with different reservoirs and pathogenicity for humans. The three most common are M. avium,…
Leprosy, or Hansen disease, is a curable infectious disease caused by Mycobacterium leprae. Widespread implementation of multidrug antibiotic therapy for leprosy in the 1980s dramatically decreased the burden of leprosy worldwide. There is no indication for physical or social isolation…
Revised March 31, 2020 Revised March 29, 2021 and June 6, 2021 The term tuberculosis describes a broad range of clinical illnesses caused by Mycobacterium tuberculosis (or, less commonly, Mycobacterium bovis ). Tuberculosis (TB) is the leading cause of death…
Both anaerobic cocci and anaerobic gram-positive nonsporulating bacilli belong to the commensal microbiota of the digestive tract, and some are members of the microbiota of the urogenital tract and skin. When the environment changes due to trauma, immunosuppression, or antimicrobial…
Overview The genera Bacteroides, Porphyromonas, Prevotella, and Fusobacterium account for most infections caused by gram-negative anaerobic rods (GNARs). Bilophila and Sutterella also cause human infections, although they are less frequently encountered in clinical practice. These obligately anaerobic gram-negative bacteria colonize…
The genus Clostridium includes over 200 described species. Members of this genus participate in a variety of invasive and toxigenic infections. They can cause disease that is strictly toxin mediated, such as antibiotic-associated colitis (AAC) and foodborne botulism, or contribute…
Botulism and tetanus result from intoxication with the protein neurotoxins elaborated by two related species of Clostridium. The toxins are very similar in structure and function but differ dramatically in their clinical effects because they target different cells in the…
History Tetanus was well known to the ancients; descriptions by Egyptian and Greek physicians survive to the present. They recognized the frequent relationship between injuries and the subsequent development of fatal spasms. Gowers provided the quintessential description of tetanus in…