Leptospira interrogans
المؤلف:
Cornelissen, C. N., Harvey, R. A., & Fisher, B. D
المصدر:
Lippincott Illustrated Reviews Microbiology
الجزء والصفحة:
3rd edition , p168-169
2025-07-20
563
L. interrogans infection causes the disease leptospirosis. The organism is a slender (lepto = slender), tightly coiled, culturable spirochete with a single, thin, axial filament and hooked ends (Figure 1). L. interrogans is an obligate aerobe. Many serovars have been characterized based upon polysaccharide differences in the LPS component in the outer membrane, and these serovars are specific to distinct geographic locales. L. interrogans is sensitive to drying and a broad range of disinfectants. It can, however, survive for weeks in slightly alkaline water.
Fig1. A. Dark-field micrograph of Leptospira interrogans. B. Electron micrograph of one end of a negatively stained Leptospira interrogans showing the axial fibril.
A. Epidemiology and pathogenesis
Leptospirosis is essentially an animal disease that is coincidentally transmitted to humans, primarily by water or food contaminated with animal urine. Entrance to the body can also occur via small skin abrasions or the conjunctiva. Although leptospirosis occurs worldwide (under various local names, such as infectious jaundice, marsh fever, Weil disease, and swineherd’s disease), the incidence of the disease today in developed countries is very low. Less than 100 cases of clinically significant L. interrogans infections are reported annually in the United States.
B. Clinical significance
Fever occurs 1 to 2 weeks after infection, at which time spirochetes appear in the blood. These symptoms decrease after about 1 week. However, in cases of biphasic disease (that is, the disease having two stages), spirochetes reappear, accompanied by invasion of the liver, kidneys, and CNS. This results in jaundice, hemorrhage, tissue necrosis, and/or aseptic meningitis. This second stage of the disease, which lasts 3 or more weeks, involves a rise in circulating immunoglobulin M antibodies. Protective immunity develops following disease, but it is serovar specific. In severe cases of the disease, mortality can be as high as 10 percent.
C. Diagnosis and treatment
Although L. interrogans can be cultured, diagnosis is usually based on serologic agglutination tests and visual demonstration of the spirochetes in urine, blood, or cerebrospinal fluid. Penicillin or doxycycline is useful if administered during the first stage of the dis ease, but both are ineffective later (Figure 2). No vaccine is currently available. Prevention of exposure to potentially contaminated water and food helps control the transmission of L. interrogans.
Fig2. Summary of Leptospira species. 1 Indicates first-line drugs.
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