The genus Neisseria contains two important human pathogens: Neisseria meningitidis and Neisseria gonorrhoeae. Neisseria meningitidis mainly causes meningitis and meningococcemia (Figure 16–1). In the United States, it is the leading cause of death from infection in children. Neisseria gonorrhoeae causes gonorrhea (Figure 16–2), the second most common notifiable bacterial disease in the United States (Tables 16–1 and 16–2). It also causes neonatal conjunctivitis (ophthalmia neonatorum) (Figure 16–3) and pelvic inflammatory disease (PID). Note that N. meningitidis is also known as the meningococcus (plural, meningococci), and N. gonorrhoeae is also known as the gonococcus (plural, gonococci).
Additional information regarding the clinical aspects of infections caused by the organisms in this chapter is provided in Part IX entitled Infectious Diseases beginning on page 593.
Meningococcemia. Note purpuric lesions on leg caused by endotoxin-mediated disseminated intravascular coagulation (DIC). (Reproduced with permission from Wolff K, Johnson R (eds): Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology. 6th ed. New York: McGraw-Hill, 2009. Copyright © 2009 by The McGraw-Hill Companies, Inc.)
Gonorrhea. Note purulent urethral discharge caused by Neisseria gonorrhoeae. (Reproduced with permission from Wolff K, Johnson R (eds): Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology. 6th ed. New York: McGraw-Hill, 2009. Copyright © 2009 by The McGraw-Hill Companies, Inc.)
Neonatal conjunctivitis (ophthalmia neonatorum) caused by Neisseria gonorrhoeae. Note purulent exudate, especially on lower right eyelid. The other common cause of neonatal conjunctivitis is Chlamydia trachomatis.
TABLE 16–1Neisseriae of Medical Importance1 |Favorite Table|Download (.pdf) TABLE 16–1 Neisseriae of Medical Importance1
|Species ||Portal of Entry ||Polysaccharide Capsule ||Maltose Fermentation ||β-Lactamase Production ||Available Vaccine |
|N. meningitidis (meningococcus) ||Respiratory tract ||+ ||+ ||None ||+ |
|N. gonorrhoeae (gonococcus) ||Genital tract ||– ||– ||Some ||– |
TABLE 16–2Important Clinical Features of Neisseriae |Favorite Table|Download (.pdf) TABLE 16–2 Important Clinical Features of Neisseriae
|Organism ||Type of Pathogenesis ||Typical Disease ||Treatment |
|N. meningitidis ||Pyogenic ||Meningitis, meningococcemia ||Penicillin G |
|N. gonorrhoeae ||Pyogenic || || |
| ||1. Local ||Gonorrhea (e.g., urethritis, cervicitis) ||Ceftriaxone1 plus doxycycline2 |
| ||2. Ascending ||Pelvic inflammatory disease ||Cefoxitin plus doxycycline1,2 |
| ||3. Disseminated ||Disseminated gonococcal infection ||Ceftriaxone1 |
| ||4. Neonatal ||Conjunctivitis (ophthalmia neonatorum) ||Ceftriaxone3 |