Moraxella catarrhalis is an unencapsulated gram-negative diplococcus and is a human-specific pathogen that colonizes the respiratory tract beginning in infancy. Patterns of colonization and infection with M. catarrhalis are changing in countries where pneumococcal conjugate vaccines are used widely. The…
Chancroid is a sexually transmitted disease characterized by painful genital ulceration and inguinal lymphadenopathy. Etiology and Epidemiology Chancroid is caused by Haemophilus ducreyi, a fastidious gram-negative bacillus. It is prevalent in many developing countries but occurs sporadically in the developed…
Effective vaccines to prevent Haemophilus influenzae type b (Hib) disease, introduced in the United States and most other countries, have resulted in a dramatic decrease in the incidence of infections caused by this organism. However, mortality and morbidity from Hib…
Kingella kingae is being increasingly recognized as the most common etiology of septic arthritis, osteomyelitis, and spondylodiscitis in young children. Etiology Kingella kingae is a fastidious, facultative anaerobic, β-hemolytic member of the Neisseriaceae family that appears as pairs or short…
Neisseria gonorrhoeae is the causative agent of gonorrhea , an infection of the genitourinary tract mucous membranes and of the mucosa of the rectum, oropharynx, and conjunctiva. Gonorrhea transmitted by sexual contact or perinatally is second only to chlamydial infections…
Neisseria meningitidis (the meningococcus) is a commensal of the human nasopharynx in approximately 10% of the population and rarely enters the bloodstream to cause devastating invasive disease such as meningitis and meningococcal septicemia (meningococcemia). Although a rare endemic disease in…
A number of Nocardia species have been identified as the source of both local and disseminated disease in children and adults. These organisms are primarily opportunistic pathogens infecting immunocompromised persons. Infection caused by these bacteria is termed nocardiosis , which…
Actinomyces species are anaerobic or microaerophilic, nonsporulating, nonmotile gram-positive bacteria that have a filamentous and branching structure. Infection caused by these bacteria is termed actinomycosis, which often presents as an indolent granulomatous, suppurative process with potential for direct extension to…
Listeriosis in humans is caused principally by Listeria monocytogenes, 1 of 6 species of the genus Listeria that are widely distributed in the environment and throughout the food chain. Human infections can usually be traced to an animal reservoir. Infection…
Diphtheria is an acute toxic infection caused by Corynebacterium species, typically Corynebacterium diphtheriae and, less often, toxigenic strains of Corynebacterium ulcerans. Although diphtheria was reduced from a major cause of childhood death to a medical rarity in the Western hemisphere…