The answer is c. (Chandrasoma, pp 799–806. Cotran, pp 361–364.)
Granuloma inguinale is a rare, sexually transmitted disease that is caused by Calymmatobacterium donovani, a small, encapsulated gram-negative bacillus. Infection results in a chronic disease that is characterized by superficial ulcers of the genital region. Regional lymph node involvement produces large nodular masses that develop extensive scarring. Specialized culture medium is available, but its use is not practical. Serologic tests are also not useful. Instead, histologic examination is used to demonstrate Donovan bodies, which are organisms within the cytoplasm of macro- phages. They are seen best with silver stains or Giemsa’s stain. Chancroid is an acute venereal disease that is characterized by painful genital ulcers with lymphadenopathy. It is caused by Haemophilus ducreyi, a small, gram- negative bacillus. Gram stains of the suppurative lesions or cultures on specialized media may be used to make the diagnosis. Serologic tests are not useful. Neisseria gonorrheae, a gram-negative diplococcus, causes gonorrhea, an acute suppurative infection of the genital tract. In males it pro- duces a purulent discharge (urethritis) and dysuria. In women, it may be asymptomatic (50%), or it may produce infection of the cervix with accompanying vaginal discharge, dysuria, and abdominal pain. Ascending infections in women can lead to salpingitis, tuboovarian abscess, and pelvic inflammatory disease (PID). Fitz-Hugh–Curtis syndrome refers to peri- hepatitis infection. In newborns, infection acquired during birth can produce a purulent conjunctivitis (ophthalmia neonatorum). This disease has been prevented due to prophylactic therapy to newborn infants. A Gram stain of the urethral or cervical exudate may reveal the intracytoplasmic gram-negative diplococci, or the exudate can be cultured on special media. Serologic tests are not useful. Characteristically, N. gonorrheae produces acid from glucose, but not from maltose or lactose. The spirochete T. pallidum, the causative agent of syphilis, has not been grown on any culture media; therefore, other means are available to aid in the diagnosis of syphilis. Dark-field or immunofluorescence examination may be used to detect organisms in the genital ulcers of primary syphilis. Antibodies to cardiolipin, a substance in beef heart that is similar to a lipoid released by T. pallidum, are used to screen for syphilis. This is the basis of both the VDRL and the rapid plasma reagin (RPR) tests; however, these screening tests are not totally specific. Chlamydia species are obligate intracellular parasites that form elementary bodies and reticulate bodies. The former are small, extracellular, and infectious, while the latter are intracellular and noninfectious. Three Chlamydia species are C. psittaci, C. pneumoniae, and C. trachomatis. The last causes several human diseases including trachoma, inclusion conjunctivitis, nongonococcal urethritis, and lymphogranuloma venereum (LGV). Specialized culture media and direct examination procedures are available to aid in the diagnosis of these diseases. The regional lymph nodes in patients with lymphogranuloma venereum have a charac- teristic histologic appearance typified by necrotizing granulomas forming stellate areas of necrosis. Trachoma is the leading cause of blindness in underdeveloped countries. It is a chronic infection of the conjunctiva that eventually scars the conjunctiva and cornea. Lymphogranuloma venereum is a sexually transmitted disease that is characterized by the formation of a genital ulcer with local necrotizing lymphadenitis. The skin test for LGV is the Frei test, which consists of intradermal injection of LGV antigen. C. psittaci is the causative agent of psittacosis (parrot fever). It produces a severe pulmonary disease and should be suspected in patients with a his- tory of bird contact, such as pet shop workers or parrot owners.