Pathogenesis

The infectious form of C. trachomatis, called an elementary body, attaches specifically to receptors on the surface of the host epithelial cell, thereby signaling the cell to take in the bacterium by endo-cytosis. In the endocytic vacuole, the bacterium enlarges and becomes a non-infectious form called a reticulate body. The reticulate body divides repeatedly by binary fission, resulting in numerous elementary bodies that are released from the host cell and infect nearby cells. The infected cells release cytokines that provoke an intense inflammatory reaction. Much of the tissue damage results

Nester-Anderson-Roberts: I IV. Infectious Diseases I 25. Genitourinary I I © The McGraw-Hill

Microbiology, A Human Infections Companies, 2003

Perspective, Fourth Edition

25.6 Bacterial STDs 647

Table 25.8 Gonorrhea

© Eyes of adults and children are susceptible to the gonococcus; serious infections leading to loss of vision are likely in newborns

(2 Organisms carried by the bloodstream infect the heart valves and joints

@ The outer covering of the liver is infected when gonococci enter the abdominal cavity from infected fallopian tubes

@ Prostatic gonococcal abscesses may be difficult to eliminate

© Infection of the fallopian tubes results in scarring, which can lead to sterility or ectopic pregnancy

© The cervix is the usual site of primary infection in women

@ Urethral scarring from gonococcal infection can predispose to urinary infections by other organisms

© Scarring of testicular tubules can cause sterility

Symptoms Men: no symptoms, pain on urination, discharge; with complication impaired urinary flow, sterility, or arthritis. Women: no symptoms or pain on urination, discharge, fever, pelvic pain, sterility, ectopic pregnancy, arthritis can occur

Incubation period 2 to 5 days

Causative agent Neisseria gonorrhoeae, a Gram-negative diplococcus

Pathogenesis Organisms attach to certain non-ciliated epithelial cells by pili; phase and antigenic variation in surface proteins allows attachment to different host cells and escape from immune mechanisms. Inflammation, scarring; can spread by bloodstream

Epidemiology Transmitted by sexual contact.

Asymptomatic carriers. No immunity

Prevention and Abstinence, monogamous relationships, treatment condoms, early treatment of sexual contacts.Treatment: intramuscular ceftriaxone; fluoroquinolones

male

from the cell-mediated immune response. The infection usually involves the urethra in both men and women. In men, it spreads to the tubules that collect sperm from the testicles, causing acute pain and swelling. In women, the infection commonly involves the cervix, making it bleed easily, often with sexual intercourse. The uterus is commonly involved, causing pain and bleeding. From the uterus, the infection spreads to the fallopian tubes (figure 25.10), causing PID, and like gonorrhea, it can exit the fallopian tubes and infect the surface of the liver. Subsequent scar tissue formation is responsible for many of the serious consequences of the disease such as sterility and ectopic pregnancy. ■ endocytosis, p. 72

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