Spirochetes

File Name:            Spirochetes.pdf

File Size:               108 kb

Download              Spirochetes.pdf.zip

File summary:

           Three genera of spirochetes cause human infection: (1) Treponema, which causes syphilis and the nonvenereal treponematoses; (2) Borrelia, which causes relapsing fever and Lyrne disease; and (3) Leptospira, which causes leptospirosis (Table 24-1).

Penicillin G. Tetracycline or amoxicillin for acute; penicillin G for chronic.

The antigens of T pallidum induce specific antibodies, which can be detected by immunofluorescence or hemagglutination tests in the clinical laboratory.

Transmission & Epidemiology T pallidum is transmitted from spirochete-containing lesions of skin or mucous membranes (eg, genitalia, mouth, and rectum) of an infected person to other persons by intimate contact.

Another third remain latent; ie, no lesions appear, but positive serologic tests indicate continuing infection.

In the early latent period, which can last for a year or two after the secondary stage, the symptoms of secondary syphilis can reappear and patients can infect others.

An infected woman can transmit Tpallidum to her fetus after the third month of pregnancy.

The liter of these nonspecific antibodies decreases with effective treatment, in contrast to the specific antibodies, which are positive for life (see below).

Patients should be alerted to this possibility, advised that it may last for up to 24 hours, and told that symptomatic relief can be obtained with aspirin.

The Jarisch-Herxheimer reaction also occurs after treatment of other spirochetal diseases such as Lyme disease, leptospirosis, and relapsing fever.

It can be grown in certain bacteriologic media, but routine cultures obtained from patients (eg, blood, spinal fluid) are typically negative.

In contrast, culture of the organism from the tick vector is usually positive.

2. Borrelia recurrentis & Borrelia hermsii Borrelia recurrentis, Borrelia hermsii, and several other borreliae cause relapsing fever.

During infection, the arthropod bite introduces spirochetes, which then multiply in many tissues, producing fever, chills, headaches, and multiple-organ dysfunction.

Diagnosis is usually made by seeing the large spirochetes in stained smears of peripheral blood.

Leptospiras are tightly coiled, fine spirochetes that are not stained with dyes but are seen by darkfield microscopy.

It is divided into serogroups that occur in different animals and geographic locations.

In the United*States, dogs are the most important reservoir.

Animals excrete leptospiras in urine, which contaminates water and soil.

The illness is typically "biphasic," with fever, chills, and intense headache appearing early in the disease followed by a short period of resolution of these symptoms as the organisms are cleared from the blood.

The second, "immune," phase is most often characterized by the findings of aseptic meningitis and, in severe cases, liver damage (jaundice) and impaired kidney function.

Diagnosis is based on history of possible exposure, suggestive clinical signs, and a marked rise in agglutinating-antibody liters.

Prevention primarily involves avoiding contact with the contaminated environment.

Such spirochetes participate in mixed anaerobic infections, infected human bites', stasis ulcers, etc. Spirillum minor causes one type of rat bite fever in humans.