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.…
Historically enterococci, Streptococcus bovis, and S. equinus were grouped together as Lancefield group D streptococci. However, genomic analysis resulted in the reclassification of these organisms, and enterococci now are considered a separate genus ( Table 120.1 ). This chapter focuses…
The Pathogen and Pathogenicity Streptococcus agalactiae is the species designation for Lancefield group B Streptococcus (GBS). Colonies appear on sheep blood agar as 3- to 4-mm, grey-white colonies typically with a narrow zone of β-hemolysis; organisms are gram-positive cocci. The…
Acknowledgment The authors acknowledge use of substantial material from this chapter in the previous edition. Group A Streptococcus (GAS) is synonymous with Streptococcus pyogenes, the only species in this group of β-hemolytic streptococci. GAS is a leading pathogenic bacterium affecting…
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