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Chapter 16: Gram-Negative Cocci

NEISSERIA

Diseases

The genus Neisseria contains two important human pathogens: Neisseria meningitidis and Neisseria gonorrhoeae. N. meningitidis mainly causes meningitis and meningococcemia (Figure 16–1). In the United States, it is the leading cause of death from infection in children. N. 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).

Figure 16–1

Meningococcemia. Note purpuric lesions on leg caused by endotoxin-mediated disseminated intravascular coagulation (DIC). (Reproduced with permission from Wolff K, Johnson R. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 6th ed. New York, NY: McGraw-Hill Education; 2009.)

A photo shows the leg of a patient with Meningococcemia. There are several purple, large, rashes on the knee and the area around it.
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Figure 16–2

Gonorrhea. Note purulent urethral discharge caused by Neisseria gonorrhoeae. (Reproduced with permission from Wolff K, Johnson R. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 6th ed. New York, NY: McGraw-Hill Education; 2009.)

A photo shows the penis of a patient with Gonorrhea. There is a whitish, purulent discharge coming out of the top of the urethra.
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Figure 16–3

Neonatal conjunctivitis (ophthalmia neonatorum) caused by Neisseria gonorrhoeae. Note purulent exudate at the corner of the medial side of child’s left eye. The other common cause of neonatal conjunctivitis is Chlamydia trachomatis. Photo contributor: David Effron, M.D. (Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, et al. The Atlas of Emergency Medicine, 4th ed. New York, NY: McGraw-Hill Education; 2016.)

A photo shows a child with Neonatal conjunctivitis. The left eye of the child is swollen with white and yellow pus visible at each corner of the eye.
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Table 16–1Neisseriae of Medical Importance1
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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 –

1All Neisseriae are oxidase-positive.

Table 16–2Important Clinical Features of Neisseriae
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Table 16–2 Important Clinical Features of Neisseriae
Organism Type of Pathogenesis Typical Disease Treatment
Neisseria meningitidis Pyogenic Meningitis, meningococcemia Penicillin G
Neisseria gonorrhoeae Pyogenic    

1. Local

2. Ascending

3. Disseminated

4. Neonatal

Gonorrhea (e.g., urethritis, cervicitis)

Pelvic inflammatory disease

Disseminated gonococcal infection

Conjunctivitis (ophthalmia neonatorum)

Ceftriaxone1 plus doxycycline2

Cefoxitin plus doxycycline1,2

Ceftriaxone1

Ceftriaxone3

1Other drugs can also be used. See treatment guidelines published by the Centers for Disease Control and Prevention.

2Add doxycycline for possible coinfection with Chlamydia trachomatis.

3For prevention, use erythromycin ointment or silver nitrate drops.

Additional information regarding the clinical aspects of infections caused by the organisms in this chapter is provided in Part IX entitled Infectious Diseases beginning ...

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