Definition Neisseria gonorrhoeae , which is predominantly a sexually transmitted infection, is a common cause of urethral discharge in men and cervical discharge in women. Because N. gonorrhoeae may infect mucosal epithelial cells, it also may cause pharyngeal and rectal…
Definition Neisseria meningitidis (the meningococcus) is the cause of epidemic bacterial meningitis, fulminant sepsis (meningococcemia), milder bacteremia, and, less commonly, focal infections (such as pneumonia, septic arthritis, purulent pericarditis, urethritis, and conjunctivitis). The Pathogen N. meningitidis is an aerobic, diplococcal…
Definition Anaerobic bacteria are the predominant members of the indigenous microbiota, including the skin and the oral, gastrointestinal, and vaginal mucosa ( Fig. 273-1 ; Table 273-1 ). However, the types of predominant anaerobes differ by location. TABLE 273-1 LOCATION…
Infections Caused by Bacillus Anthracis and Other Bacillus Species Definition The genus Bacillus includes several species that are closely related phylogenetically. The Bacillus cereus group includes Bacillus anthracis , which is the causative agent of anthrax; Bacillus cereus , which…
Diarrheal Syndromes Clostridioides Difficile Infection Definition The hallmark of C. difficile infection is diarrhea, most commonly during or after (up to 3 months) a course of antibiotics. Most cases are defined by the presence of clinically significant diarrhea (three or…
Definition Enterococci are endogenous human gut flora that are increasingly important health care–associated pathogens. Enterococci cause urinary tract infections, bacteremia, intra-abdominal infections, and, rarely, endocarditis and meningitis. Their emergence as major pathogens results from their inherent resistance to commonly used…
Classification and Identification of Streptococci Streptococci are gram-positive facultatively anaerobic, catalase-negative coccoid bacteria that grow in chains and colonize the skin and mucous membranes. When grown on blood agar plates, they may cause complete (β), incomplete (α), or no (γ)…
Definition Streptococcus pneumoniae ( S. pneumoniae ) is a significant human bacterial pathogen and a major cause of community-associated bacterial infections. It is the most common bacterial cause of community acquired pneumonia (pneumococcal pneumonia; Chapter 85 ), sinusitis ( Chapter…
Definition Staphylococci are well adapted as commensals and as pathogens. Coagulase-negative species constitute a significant proportion of the normal human cutaneous microbiome. Staphylococcus aureus , a coagulase-positive species, is a nasopharyngeal colonizer in a third of individuals, most of whom…
Antibiotics provide a backbone for modern interventional medicine, in which surgery, central venous catheters, urinary catheters, implantable devices, and mechanical ventilation have become commonplace. These interventions support seriously ill patients, but they also give bacteria access to normally sterile areas.…