Diphtheria is a toxicosis caused by infection with Corynebacterium diphtheriae. The genus and species names are derived from Greek roots: korynee (“club”) after the microscopic appearance of the organisms and diphtheria (“leather hide”) for the pseudomembrane that is the hallmark…
Bacillus species, ubiquitous in the environment, are found in soil, water, dust, and air. With the exception of B. anthracis, which causes anthrax, Bacillus spp. previously have been considered nonpathogenic when isolated from clinical specimens. However, nonanthrax species are increasingly…
Arcanobacterium haemolyticum was first identified as Corynebacterium haemolyticum in 1946 in pharyngeal cultures of World War II soldiers and Pacific Islanders with pharyngitis that was indistinguishable clinically from infection caused by group A Streptococcus . Epidemiology Humans are the primary…
Neisseria gonorrhoeae and N. meningitidis are the 2 most pathogenic Neisseria species. Other Neisseria species are common commensal inhabitants of the upper respiratory tract and oral cavity of humans and other animals, but they have been implicated in clinical disease…
Neisseria gonorrhoeae is a pathogen only of humans. Gonorrhea, one of the oldest known human illnesses, continues to result in significant morbidity; an estimated 87 million cases occur worldwide each year. In the US, gonorrhea is the second most frequently…
Neisseria meningitidis (meningococcus) is an important cause of serious bacterial infections in children, most commonly manifesting as purulent meningitis or septicemia. Asymptomatic pharyngeal colonization is more common than invasive disease, and humans are the only reservoir. Gaspard Vieusseux provided the…
Characteristics Of Pathogens Among the gram-positive catalase-negative cocci, streptococci and enterococci cause most human infections. The remaining organisms belong to 5 genera that can be identified according to the criteria proposed by Facklam and colleagues ( Table 124.1 ), and…
Acknowledgments We acknowledge the contributions of Carrie Byington, MD, Georges Peter, MD and Jerome O. Klein, MD, for their work on this chapter in the previous editions. All references are available online at Elsevier eBooks for Practicing Clinicians . In…
The β-hemolytic streptococci can be subdivided on the basis of whether they form large colonies or minute colonies on solid agar. Most notable among those β-hemolytic streptococci that form large colonies are Streptococcus pyogenes (group A) and Streptococcus agalactiae (group…
The viridans streptococci are genetically diverse organisms that share the propensity to colonize humans and occasionally penetrate local barriers to cause life-threatening disease. Their importance as the predominant cause of endocarditis in children and adults has been known for decades.…