Presentation on theme: "Spirochaetales The Spirochetes. Spirochaetales Classification Spirochetes are members of the order Spirochaetales which contains 2 families Spirochaetaceae."— Presentation transcript:
Spirochaetales The Spirochetes
Spirochaetales Classification Spirochetes are members of the order Spirochaetales which contains 2 families Spirochaetaceae – contains 2 medically important genera Treponema Borrelia Leptospiraceae – 1 medically important genus Leptospira Morphology and general characteristics Is composed of: A helical protplasmic cylinder with a peptidoglycan layer similar to G-B, cytoplasmic membrane, and cytoplasm
Spirochaetales A multilayered outer membrane that surrounds the cylinder Periplasmic flagella which are attached to each end of the protoplasmic cylinder and extend toward the opposite end. Are not typical flagella and are often called axial filaments
Spirochaetales None of the pathogenic Treponemes have been successfully cultured on artificial media T. pallidum is usually cultured in the testes of rabbits, although it has been grown in tissue culture for short periods of time. T. pallidum does not survive for long outside the host. Visualized by darkfield microscopy or iron staining
Spirochaetales Borrelia may be grown on a complex media called Kelly’s media, but this is not usually done in diagnostic labs. Borrelia may be observed with darkfield microscopy or be stained in a blood sample with a Giemsa stain or Wright stain.
Borrelia sp. in blood smear
Spirochaetales Leptospira can be grown on semi-solid media containing peptone, beef extract supplemented with rabbit serum or bovine serum albumin and tween 80. Incubation may be for as long as 28 days. Visualize using darkfield microscopy Identification Treponema Observation of organisms in lesions Detection of antibodies made in the host. Two types of tests may be used:
Spirochaetales Nonspecific, nontreponemal tests – used for screening purposes Very sensitive, but not specific Many diseases give positive results Is inexpensive and easy to do Detects non-treponemal antibodies, called reagenic or Wasserman antibodies, that react with a phospholipid (cardiolipin-lecithin) that is a normal tissue constituent Tests include: VDRL test, rapid plasma reagin card tests (RPR), and automated reagin test (ART)
Spirochaetales Specific, treponemal tests – used to confirm positive nontreponemal results Very specific, expensive, and more difficult to perform Include T. pallidum immobilization tests, Fluorescent Treponemal antibody absorption test, indirect Treponemal hemagglutination test Borrelia Demonstration of Spirochetes in the blood Leptospira Isolate and culture Specific agglutination test or C’ fixation test – look for 4- fold rise in titer in patient’s antibodies against the organism
Spirochaetales Virulence factors Treponema Molecular mimicry – the outer sheath contains molecules that resemble the molecules commonly found on the surface of human cells. This allows the organism to resist host defenses. Hyaluronidase Borrelia Antigenic variation
Spirochaetales Leptospira Unknown Clinical significance Treponema T. pallidum causes venereal (transmitted by sexual contact) and non-venereal (transmitted by directly by non- sexual contact, and indirectly by common usage of eating and drinking utensils) syphilis. In venereal syphilis the primary lesion is on the genitals In non-venereal syphilis it is on oral mucous membranes. The normal untreated course of the disease occurs in several stages:
Spirochaetales Primary stage – following penetration of the skin or mucous membranes, a characteristic, painless hard chancre develops at the site of entry within 3 weeks. The chancre is highly contagious and filled with Treponemes. Simultaneously the organism enters the lymphatics and becomes disseminated. The chancre heals without treatment in a few weeks due to local immunity, but by that time the organism has already disseminated.
Spirochaetales Secondary stage – 4-8 weeks after the primary stage, the secondary stage develops. Typically there are lesions (filled with treponemes) throughout the body including the skin, mucous membranes, organs, and eyes. Most lesions are on the skin and mucous membranes. The patient may also have a loss of hair, a mild fever, and the development of malaise. This also heals without treatment and the patient may either spontaneously get well or develop a latent infection
Spirochaetales Latent infection – during this stage there are no symptoms, but specific anti-treponemal antibodies are found. This stage may last 3-10 years. During this time these is a biological balance between the organism and the host. 1/3 to ½ may eventually progress to the next stage. Tertiary syphilis – this stage is characterized by granulomatous lesions, called gummas, of the skin, internal organs, CNS, bones, eyes, and cardiovascular system. They are cause by the body’s hyperimmune reaction to remaining spirochetes. When lesions develop in the CNS it is called neurosyphilis and it can lead to paralysis. In the eyes it can lead to blindness In the heart it can lead to aortic damage or aneurisms.
Tertiary syphilis - gummas
Spirochaetales Congenital syphilis – occurs when the treponemes cross the placenta during the fifth month to infect the unborn fetus (occurs usually when mom is in the latent stage). This can result in damage to mental development or other neurological symptoms or the child may be born with generalized syphilis. In a pregnant woman who has a primary or secondary stage of the disease, this usually results in stillbirth. T. pertenue - causes Yaws or tropical syphilis which transmitted by non-venereal direct contact. T. carateum – causes Pinta, a skin disease with hyperpigmentation in patches.
Spirochaetales Borrelia – are arthropod transmitted Spirochetes and they cause: Relapsing fever – two types: Epidemic – is caused by B. recurrentis and is transmitted by human lice. This is a more severe form of the disease than the endemic form. Endemic – is caused by many Borrelia species and is transmitted by ticks Both types of relapsing fever follow the same clinical pattern days after infection there is an abrupt onset of fever, headache, and myalgia for 4-10 days. Antibodies are formed and the number of organisms decrease. This leads to an afebrile period for a few days to several weeks
Spirochaetales The fever then relapses because the organism has undergone antigenic variation. The antibodies are no longer effective and the organism numbers increase. Several relapses may occur with each one being less severe than the previous one. Lyme disease – caused by Borrelia burgdorferi and transmitted by ticks. This is a systemic illness that may begin with the appearance of a red skin lesion called erythema chronicum migrans (ECM) because the lesion expands in a circular manner. The patient may also have a fever, headache, nausea, vomiting, myalgia, and fatigue. If untreated, the patient may develop arthritis (acute or chronic), and cardiac or neurologic complications weeks or months later due to immune complexes.
ECM – from Lyme disease
Spirochaetales Leptospira – L. interrogans causes Weil’s disease or leptospirosis This disease is acquired by contact with the urine of an infected animal or ingestion of contaminated food or water. It is more a disease of animals other than man. Infection can vary from asymptomatic to fulminant. The CNS, liver, and kidneys are most commonly infected.
Spirochaetales In most cases the incubation is 2-20 days followed by fever, chills, severe headache, myalgia, malaise, nausea and vomiting. Jaundice occurs in severe cases Death may occur due to renal failure. Antibiotic therapy/treatment Treponema – penicillin, tetracycline, or erythromycin Borrelia - for relapsing fever use tetracycline or erythromycin; for Lyme disease use amoxicillin or doxycycline Use protective clothing and repellents to prevent infection Leptospirosis provide supportive care; antibiotics (penicillin or erythromycin) are only effective if given during the first 2-4 days of illness