Essentials of Anatomy and Physiology

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Table 22–3 DISEASES CAUSED BY BACTERIA (Continued)

Bacterial Species Discussion/Disease(s) Caused

Mycobacteriumspecies

acid-fast bacillus

Mycobacterium leprae

acid-fast bacillus

Treponema pallidum

spirochete

Leptospira interrogans

spirochete

Borrelia burgdorferi

spirochete

Borrelia vincentii

spirochete

Rickettsia prowazekii

rickettsia

Rickettsia typhi

rickettsia

Rickettsia rickettsii

rickettsia

Chlamydia trachomatis

(serogroups D–K)

chlamydia

Chlamydia trachomatis

(serogroups A–C)

chlamydia

Chlamydia pneumoniae

chlamydia

Chlamydia psittaci

chlamydia

Atypical mycobacterial infections: clinically similar to TB; usually in the lungs. These bacteria

are pathogenic for people with AIDS or other forms of immunosuppression, and for those

with chronic pulmonary diseases.

Leprosy (Hansen’s disease): chronic disease characterized by disfiguring skin lesions and

nerve damage that may cause paralysis or loss of sensation. The bacteria are acquired by

cutaneous contact or respiratory droplets. The incubation period may be several years;

children develop clinical disease more rapidly than do adults. A vaccine is in the testing

stage.

Syphilis: a sexually transmitted disease that progresses in three stages. Primary syphilis: a

painless, hard chancre at the site of entry on skin or mucous membrane. Secondary

syphilis: a rash on the skin and mucous membranes (indicates systemic infection). Tertiary

syphilis (5–40 years later): necrotic lesions (gummas) in the brain, heart valves, aorta,

spinal cord, skin, or other organs. Congenital syphilis (the bacteria can cross the placenta)

may cause bone and teeth defects, and mental retardation. The WHO estimates that

more than 12 million new cases occur worldwide every year, a serious public health prob-

lem. No vaccine.

Leptospirosis: a disease of wild or domestic animals that excrete the bacteria in urine. People

acquire the bacteria by contact with contaminated water. Disease is usually mild, resem-

bling intestinal virus infection. Weil’s disease is the serious form, with hemorrhages in the

liver and kidneys, and jaundice always present, indicating severe liver damage. A vaccine

is available for dogs.

Lyme disease: begins as a flu-like illness, often with a bull’s-eye rash at the site of the tick

bite. May be followed by cardiac arrhythmias, self-limiting meningitis, or arthritis. Animal

reservoirs are deer and field mice; the vector is the deer tick (genus Ixodes). The vaccine

was taken off the market because of poor sales.

Trench mouth (Vincent’s gingivitis): an ulcerative infection of the gums and pharynx caused

by overgrowth of Borreliaand other normal oral flora. Triggered by poor oral hygiene or

oral infection, which must be corrected to make antibiotic therapy effective.

Epidemic typhus: high fever and delirium, hemorrhagic rash; 40% fatality rate. Vector is the

human body louse. Very rare in the U.S. but still endemic in other parts of the world.

Endemic typhus: similar to epidemic typhus but milder; 2% fatality rate. Reservoirs are rats

and wild rodents; vectors are fleas. The few cases in the U.S. each year usually occur in

the Southeast.

Rocky Mountain spotted fever (RMSF): high fever, hemorrhagic rash, and pneumonia; 20%

fatality rate. Reservoirs are wild rodents and dogs; vectors are ticks. Despite its name,

RMSF in the U.S. is most prevalent in the Southeast coastal states (North Carolina, South

Carolina) and in Oklahoma.

Genitourinary infection (nongonococcal urethritis): in men, urethritis or epididymitis; in

women, cervicitis, although many women are asymptomatic. Complications in women

include pelvic inflammatory disease, ectopic pregnancy, and miscarriage. Newborns of

infected women may develop conjunctivitis or pneumonia. This is one of the most preva-

lent sexually transmitted diseases in the U.S. No vaccine.

Trachoma: conjunctivitis involving growth of papillae; vascular invasion of the cornea leading

to scarring and blindness. Spread by direct contact and fomites. The leading cause of

blindness throughout the world, especially in dry, dusty environments.

Pneumonia, usually community-acquired and mild enough to be called “walking pneumo-

nia,” with fever, cough, and hoarseness. No vaccine. C.pneumoniaeas a factor in coro-

nary artery disease has not yet been demonstrated conclusively.

Psittacosis, also called ornithosis or parrot fever. Reservoirs are wild and domestic birds,

which shed the pathogen in feces. Acquired by people by inhalation of fecal dust. Disease

ranges from mild upper respiratory infection to a more serious pneumonia. No vaccine.