Cell Wall Defective Bacteria

Spirochetes(Spiral bacteria)

Classification
Domain: Bacteria Family : Spirochetaceae (free living spirochetes) Treponemataceae (human pathogens) Genus: Treponema Borrelia leptospira

General Features

General Features
Axial filament runs between the bacterial inner and outer membranes in the periplasmic space Very actively motile Reproduce by traverse binary fission

Genus : Tryponema

4 spp (subspecies) T pallidum subspecies pallidum (T pallidum) Syphilis T pallidum subspecies pertenue (T pertenue) Yaws T pallidum subspecies endemicum (T endemicum) Endemic syphilis (bejel) T carateum Pinta

T pallidum subspecies pallidum

Microaerophilic organisms , survives best in 1-4 % O2 Never been cultured on artificial growth media or tissue culture. Obligate intracellular parasites and therefore cant be transmitted by public surfaces because of its narrow temperature and pH ranges (can not survive in temperature higher than 42 C and their optimal pH range is 7.2 - 7.4)

Growth and cultural characteristics

Growth and cultural characteristics
Exposure to air, antiseptic or sunlight kill it Invivo generation time very long about 30 hours All spp sensitive to penicillin

Antigenic structures

Not widely characterized more than 100 protein antigens Outer membrane lipoproteins Endoflagellar antigens

Pathogenesis, pathology and clinical findings

- T pallidum infection is limited to human host (animals can only be infected experimentally) - Infection with T pallidum cause a disease called Syphilis - Syphilis can be divided into two main types Acquired syphilis Congenital syphilis

Pathogenesis, pathology and clinical findings

Acquired syphilis - Transmitted by sexual intercourse - 3 stages Primary stage - Multiply locally at the site of entry - Painless chancre lesion (painless ulcer) on skin and mucous membrane of external genetalia

Pathogenesis, pathology and clinical findings

- 10-20% of cases the 1ry lesion is intra-rectal or peri-anal or oral - Lasts for 2-6 weeks and then recede even without treatment (you should treat it!!!!) - Highly infectious stage and lesion rich in spirochetes

Secondary stage - Develop 2-10 weeks after the infection - None specific symptoms maculo-papular rash, fatigue, fever sore throat headaches , loss of appetite and lymphadenopathy - Also subsides spontaneously - Like 1ry stage, 2ry lesions are rich in spirochetes and highly contagious

Pathogenesis, pathology and clinical findings

Pathogenesis, pathology and clinical findings
Tertiary stage - 30 % of patents with syphilis progress to complete cure even without treatment - Another 30% of patents , untreated infections remain latent (evident by positive serological reactions) - About 40 % of patients progress to tertiary syphilis


Pathogenesis, pathology and clinical findings
Tertiary stage - Granulmatous lesions (GUMMAS) in skin , bones, joints and liver - Degenerative changes in CNS including syphilitic meningitis, paralysis , difficulties in movements, stroke, numbness and gradual blindness - Cardiovascular syphilitic lesions (aortitis, aortic aneurysm an aortic valve insufficiencies - Not infectious stage, tryponema very rarely isolated and lesions are attributed to hypersensitivity to organism

Congenital syphilis- From pregnant woman to fetus through placenta- Usually begins in the 10th to 15th weeks of gestation- Consequences • Some of the infected fetuses die and abortion result • Some are stillbirth at delivery Pathogenesis, pathology and clinical findings


Congenital syphilis • Some fetuses born life but die soon after birth • Some fetuses born life but develop signs of congenital syphilis in childhood, these include - Varity of CNS anomalies - Deafness - Teeth deformities - Saddle nose Pathogenesis, pathology and clinical findings

Laboratory Diagnosis

• Specimen- Tissue fluid expressed from early surface lesions for identification of spirochetes- Blood or serum for serology• Direct testing - Dark - field examination (should be before the starting of antibiotic treatment) - IF

Laboratory Diagnosis

• Serology- Two types : - None treponemal serological tests (detect none trponemal antigens or antibodies) - Treponemal serological tests (detect treponemal antigens or antibodies)

None treponemal serological tests - None specific tests - Used for screening - Look for cardiolipins (Indirect indications of the infection with T pallidum - Cardiolipin shares some antigenic determinants with T pallidum - They indicate either active infection or healed but not treated infection

Laboratory Diagnosis

- Two types VDRL (Venereal Disease Research Laboratory) test RPR (Rapid Plasma Reagin) test - The only difference between the two the later does not need a microscope to read the result


Laboratory Diagnosis

- Positive test is indicated by the formation of clusters - If positive, go with treponemal serological tests

Laboratory Diagnosis

- Ve VDRL test
+ Ve VDRL test


Disadvantages of None treponemal serology - Not specific (false positive can occur with other conditions such us pregnancy , HIV, TB, and rheumatoid arthritis - Not very sensitive in early syphilis, specially in the first 2-3 weeks after the infection (false negative)
Laboratory Diagnosis


Disadvantages of None treponemal serology - Not specific (false positive can occur with other conditions such us pregnancy , HIV, TB, rheumatoid arthritis - Not very sensitive in early syphilis, specially in the first 2-3 weeks after the infection (false negative)

Treponemal serological tests - Indicated if non treponemal serological tests are positive - Detect treponemal antigens or antibodies - Remains positive for life (not useful for screening) - Many types: Fluorescent treponemal antibody (FTA) Treponema pallidum particle agglutination ELISA
Laboratory Diagnosis


Sensitive to penicillin ( treatment of choice) If patient is allergic, tetracycline and erythromycin can be substituted but they are generally less effective than penicillin No permanent immunity. If the disease is treated, the individual again becomes fully susceptible to re-infection
Treatment and Immunity



• T pallidum subspecies pertenue Yaws• T pallidum subspecies endimicum Bejel - Non sexually transmitted diseases - Affect children in hot tropical countries - 1ry lesion is an ulcerating macule or papule on arms and legs. Complications rare - Yaws is a variant of syphilis (????) - Sensitive to penicillin ( treatment of choice) Other Treponema subspecies

• T carateum Pinta - Non sexually transmitted disease - Affect all age groups in Mexico and South America (restricted to dark skinned people) - 1ry lesion is non ulcerating macule on exposed areas changes later on to hyperpigmented lesions. Complications rare - Diagnosis and treatment like syphilis Other Treponema subspecies