spiros.pptx presentation with treponemas

spirochaetes

1. SPIROCHETES

2. CHARACTERISTICS AND MORPHOLOGY Spirochaetes (also spelled spirochetes) belong to a phylum of distinctive diderm ( doublemembrane ) bacteria, most of which have long, helically coiled (corkscrew-shaped) cells. Spirochaetes are chemoheterotrophic in nature, with lengths between 5 and 250 µm and diameters around 0.1–0.6 µm.

3. Spirochaetes are distinguished from other bacterial phyla by the location of their flagella, sometimes called axial filaments, which run lengthwise between the bacterial inner membrane and outer membrane in periplasmic space These cause a twisting motion which allows the spirochaete to move about.

4. When reproducing, a spirochaete will undergo asexual transverse binary fission. In addition, the spirochetes are microaerophilic or anaerobic and are extremely sensitive to oxygen toxicity. The complete genome sequence has revealed there are no genes for catalase or superoxide dismutase. The order of Spirochaetales is divided into two families: 1. Spirochaetaceae 2. Leptospiraceae

5. Two of the four genera of Spirochaetaceae , Treponema and Borrelia , include species that are pathogenic to man. Among Leptospiraceae , only one genus, Leptospira , has pathogenic species. Disease-causing members are Leptospira species, Borrelia burgdorferi , B. garinii , B. afzelii , Borrelia recurrentis , Treponema pallidum subspecies, Brachyspira pilosicoli and Brachyspira aalborgi

6. Cultural Characteristics of Spirochetes Spirochetes are typically fastidious organisms that require specialized culture media for growth. Commonly used media for culturing spirochetes include Kelly- Pettenkoffer agar, Barbour- Stoenner -Kelly medium, and BSK-H medium. Spirochetes are often slow-growing bacteria, with generation times ranging from several hours to days. This slow growth rate necessitates prolonged incubation times for visible growth to occur in culture.

7. Spirochetes are microaerophilic organisms, meaning they require low levels of oxygen for optimal growth. Therefore, culture media for spirochetes should be incubated in an environment with reduced oxygen tension. Spirochetes can be sensitive to changes in pH, temperature, and osmotic pressure. It is important to maintain optimal conditions for growth, as variations in these factors can affect the viability and growth of spirochetes in culture.

8. Some spirochetes require specific nutrients for growth, such as fatty acids, amino acids, vitamins, and trace minerals. Culture media should be supplemented with these nutrients to support the growth of spirochetes Spirochetes are highly motile organisms and exhibit characteristic corkscrew-like motility. This motility can be observed microscopically in wet mounts of cultured spirochetes.

9. Spirochetes may form distinctive colony morphologies on solid agar media, such as flat, spreading colonies with irregular edges. These colony characteristics can aid in the identification of spirochetes in culture.

10. Biochemical characteristics of spirochetes Catalase Test:Treponema pallidum typically exhibits a negative catalase test, indicating the absence of catalase enzyme production. Oxidase Test:Most spirochetes, including Leptospira interrogans and Borrelia burgdorferi , are oxidase-positive, producing cytochrome c oxidase. Indole Production:Some spirochetes like Leptospira interrogans are capable of producing indole from tryptophan.

11. Carbohydrate Fermentation:Leptospira interrogans ferments carbohydrates like glucose and maltose, producing acids and gases.Treponema pallidum and Borrelia burgdorferi are generally non-fermenters. Sensitivity to Antibiotics:Treponema pallidum is sensitive to antibiotics like penicillin and doxycycline.Borrelia burgdorferi is commonly treated with antibiotics such as doxycycline, amoxicillin, or cefuroxime.

12. VIRULENCE FACTORS Flagella: Spirochetes use flagella for motility, allowing them to move through various environments, including host tissues. Adhesins : These are surface proteins that enable spirochetes to adhere to host cells and tissues, facilitating colonization and invasion. Endoflagella : Also known as axial filaments, these are unique to spirochetes and are involved in their motility within host tissues.

13. Antigenic variation: Spirochetes can undergo rapid changes in surface antigens, evading the host immune response and establishing chronic infections. Toxins: Some spirochetes produce toxins that damage host tissues and contribute to disease progression. For example, the neurotoxin produced by Treponema pallidum contributes to the neurological manifestations of syphilis.

14. PATHOGENICITY Treponema pallidum: This bacterium causes syphilis, a sexually transmitted infection that progresses through distinct stages if left untreated. Syphilis can affect multiple organ systems, including the skin, cardiovascular system, central nervous system, and bones. Borrelia burgdorferi : Transmitted by the bite of infected ticks, this spirochete is responsible for Lyme disease. Lyme disease can affect the skin, joints, nervous system, and heart, leading to a range of symptoms such as rash, arthritis, neurological issues, and cardiac abnormalities.

15. Leptospira spp.: These spirochetes cause leptospirosis, a zoonotic disease transmitted through contact with water or soil contaminated with the urine of infected animals. Leptospirosis can lead to systemic symptoms such as fever, headache, muscle aches, and can progress to involve multiple organ systems, including the liver, kidneys, lungs, and central nervous system.

16. Borrelia recurrentis : This spirochete causes relapsing fever, a febrile illness characterized by recurring episodes of fever interspersed with asymptomatic periods. It can lead to systemic complications if not treated promptly.

17. LABORATORY DIAGNOSIS OF SPIROCHETES. Samples : Tissue fluids or lesions, serum. Microscopy: Dark-field or phase-contrast microscopy can visualize spirochetes in clinical samples like blood, cerebrospinal fluid, tissue biopsy specimens, and exudates from body lesions. Culture: Spirochetes can be cultured using specialized media under appropriate conditions, but requires specialized expertise. Optimal conditions include temperature between 33°C-35°C, atmospheric oxygen concentration in the 1,5% - 5% range, 20% foetal bovine serum in the culture medium, and the testes extract.

18. Serological Tests: Serological tests like ELISA or FTA-ABS test detect antibodies produced by the host against spirochaetal antigens. Direct fluorescent antibody test is more useful for detecting T. pallidum. Polymerase Chain Reaction (PCR): PCR can detect spirochaetal DNA in clinical samples with high sensitivity and specificity. Immunohistochemistry: Technique involves using specific antibodies to detect spirochetes in tissue biopsy specimens.

19. Antigen Detection: Tests are available for some spirochetal diseases, such as urine antigen test for leptospirosis. Tissue Biopsy: Treponema pallidum can be demonstrated in tissues by silver staining or immunofluorescence.

20. Treatment of spirochetes Borrelia burgdorferi (Lyme disease): Early stage: Doxycycline, amoxicillin, cefuroxime. Late stage: Ceftriaxone, doxycycline, or penicillin. Borrelia garinii and B. afzelii (Lyme disease, different species): Early stage: Doxycycline, amoxicillin, cefuroxime. Late stage: Ceftriaxone, doxycycline, or penicillin.

21. Treponema pallidum subspecies (Syphilis): Early stage: Penicillin. Late stage: Penicillin, typically in higher doses. Brachyspira pilosicoli (intestinal spirochetosis ): Treatment options: tetracycline or metronidazole. Specific guidance required.

22. Control measures for spirochetes Borrelia burgdorferi (Lyme disease) - Avoidance of tick-infested areas. - Wearing protective clothing, such as long sleeves and pants. - Using insect repellents. - Conducting thorough tick checks after outdoor activities. Borrelia garinii and B. afzelii (Lyme disease, different species) - Similar control measures as for B. burgdorferi . Borrelia recurrentis (Relapsing fever) - Reducing exposure to lice by maintaining personal hygiene. - Proper management of louse infestations.

23. Treponema pallidum subspecies (Syphilis) - Safe sexual practices, including condom use. - Routine testing and early treatment for infected individuals. - Partner notification and testing. Brachyspira pilosicoli (intestinal spirochetosis ) - Improved sanitation and hygiene practices. - Prevention of fecal-oral transmission through safe water and food handling. Brachyspira aalborgi (intestinal spirochetosis ) - Similar control measures as for B. pilosicoli .