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Abortion

Microorganisms causing abortion By Dr. Sahar Zakaria L ecturer of Microbiology and Medical Immunology. Abortion. It is the expulsion of a fetus from the uterus before it has reached the stage of viability (usually about the 20th week of gestation).

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Abortion

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  1. Microorganisms causing abortionByDr. Sahar ZakariaLecturer of Microbiology and Medical Immunology

  2. Abortion • It is the expulsion of a fetus from the uterus before it has reached the stage of viability (usually about the 20th week of gestation). • An abortion may occur spontaneously, in which case it is also called a miscarriage, or it may be brought on purposefully, in which case it is often called an induced abortion.

  3. Microorganisms causing abortion: (1) Treponema pallidum (Syphilis). (2) Listeria monocytogenes. (3) Rubella virus. (4) Cytomegalovirus. (5) Varicella-Zoster virus. (6) Parvovirus B19. (7) Toxoplasma.

  4. Syphilis • Causative agent: • It is caused by a spirochaete called Treponema pallidum. • It is a delicate spiral filaments with small regular coils and a characteristic motility. • Seen by dark-ground microscopy. • Stained by silver impregnation and immunofluorescence methods.

  5. Cultural characters: • Not cultivated on artificial media. • Grown anaerobically in digest broth enriched with serum. • Nichol’s strain of T. pallidum can be propagated in the testicles of rabbit.

  6. Serological characters: • Antigenic structure is unknown. • Stimulates the formation of two types of antibodies: (1) A treponemal antibody →reacts with treponema suspensions. (2) A second antibody (reagin)→ reacts with a non-specific antigen (cardiolipin).

  7. Virulence factors: (1) The outer membrane → associated with adherence to the surface of host cells. (2) Production of hyaluronidase → facilitates perivascular infiltration.

  8. Transmission: (1) Sexually. (2) Transplacentally →from mother to fetus. (3) By blood transfusion. (4) As a clinical hazard →in hands of doctors and nurses by contact with patients.

  9. Pathogenesis: • Three stages: (1)The primary stage: • A hard painless ulcer called chancre at the site of inoculation. • Begins as a papule that ulcerates. • Appears 2-10 weeks after exposure. • Appears mainly on genitalia. • Regional lymph nodes are enlarged. • Heals spontaneously within 4-6 weeks.

  10. (2)The secondary stage: • 6-12 weeks after the appearance of chancre. • Generalized manifestations → skin rash, condylomata of anus and vulva, and mucous patches in the mouth. • Systemic manifestations →fever, weight loss, joint pains, hair loss. • T. pallidum is present in large numbers in the lesions. • Symptoms disappear spontaneously in 3-6 months. • Followed by a latent stage which is characterized by: - Asymptomatic. - Lasts for few months or for lifetime. - The organism is still present in the blood.

  11. (3) The tertiary stage: • Occurs in 30% of untreated cases. • Granulomas (gumma) appear in the skin and bones. • CNS lesions → tabes, paresis. • Cardiovascular lesions → aortitis, aneurysm of aorta. • Treponema are rarely seen in the lesions.

  12. Congenital syphilis: • A syphilitic woman transmits the infection to the fetus transplacentally. • This leads to 1. abortion. 2. stillbirth. 3. congenital syphilis. • Congenital syphilis→ interstitial keratitis, Hutchinson’s teeth, saddle nose, CNS anomalies, IgM antitreponemal antibodies.

  13. Diagnosis: I. Detection of spirochaetes in the lesion: (1) Dark-ground microscopy. (2) Direct immunofluorescence. (3) PCR. II. Serological diagnosis: Two types according to the type of antigen used: (1) Non-specific → using nontreponemal antigens. (2) Specific → using treponemal antigens.

  14. (1)Non-treponemal antigen tests: • Detect the “reagin” antibody which react with a non-specific antigen “cardiolipin”. • 1. Venereal Disease Research Laboratory (VDRL). 2. Rapid Plasma Reagin (RPR). 3. Toluidine Red UnheatedSerum Test (TRUST). • Used in: 1. Screening. 2. Evaluation of treatment.

  15. (2)Treponemal antigen tests: • Detect antitreponemal antibodies. • 1. Fluorescent treponemal antibody absorption (FTA-ABS) tests. 2.T. pallidum haemagglutinin (TPHA) tests. 3.T. pallidum particle agglutination (TPPA) tests. 4. Enzyme-linked immunosorbent assay (ELISA). • Used as confirmatory tests. • Remains positive for life.

  16. Listeria monocytogenes • Morphology: • Gram-positive, non-spore forming bacilli. • Motile →tumbling movement at 22-28°C but not at 37ºC. • Produce β-hemolysis on blood agar.

  17. Transmission: • Found in animals, soil, and plants. • Transmitted by: (1) Contact with domestic farm animals or their faeces. (2) Ingestion of contaminated unpasteurized milk or cheese. (3) Contaminated vegetables. • Can grow at refrigerator temperature.

  18. Pathogenesis: • Listeria is an intracellular organism. • Listeria → phagocytosed by mononuclear phagocytic cells → phagosome → fused with the lysosome to form a phagolysosome → the listeria produces listeriolysin O which lyses the membrane of the phagolysosome → listeria escape destruction → move from one cell to another. • Host defense is by cell-mediated immunity.

  19. Listeriosis: (1)Transplacental infection→ granulomatosis infantiseptica → skin lesions and intrauterine sepsis → abortion, stillbirth, or premature labour. (2)Infection during delivery→ neonatal meningitis. (3)Infection in immunosuppressed adults→ meningoencephalitis and bacteremia. (4)Gastroenteritis→ watery diarrhea, fever, headache, myalgia, abdominal cramps, but little vomiting → outbreaks may occur.

  20. Diagnosis: • Isolation of listeria from: - Blood → by blood culture. - CSF → on blood agar. - Stool → on listeria selective media. • Cold enrichment for few days. • Identified by: 1. gram stain. 2. charateristic tumbling movement. 3.β-hemolysis on blood agar. 4. positive catalase test.

  21. Rubella • Causative agent: Rubella virus • Belongs to togavirus family. • Enveloped with surface spikes. • Icosahedral nucleocapsid. • Single-stranded RNA genome. • One antigenic type. • Man is the only host.

  22. Transmission: (1) Respiratory route → adults. (2) Transplacental route → from mother to fetus. • According to the route of transmission, two clinical forms exist: (1) Postnatal Rubella. (2) Congenital rubella syndrome.

  23. Pathogenesis: (1) Postnatal Rubella: • Incubation period is 2-3 weeks. • Enter through the respiratory route →replicate in the nasopharynx and regional lymph nodes → spread via blood → reach the internal organs and skin → fever, skin rash, and enlargement of posterior occipital lymph nodes.

  24. (2) Congenital Rubella Syndrome: • Early intrauterine infection in the first trimester may lead to (1) Abortion / intrauterine fetal death. (2)Congenital rubella syndrome→congenital heart defects, deafness, blindness, cataract, meningoencephalitis, mental retardation, and hepatosplenomegaly. The virus is shed in pharyngeal secretions and other body fluids for up to 18 months after birth.

  25. Diagnosis: • Pregnant woman → detection of rubella antibodies: . IgM in a single serum sample. . Rising IgG titre in paired sera. • Fetus → isolation of the virus from the amniotic fluid. • Newborn →1. detection of rubella IgM. 2. Isolation of the virus from the newborn secretions.

  26. Cytomegalovirus • Morphology & pathogenesis: • Belongs to Herpesviruses family. • Enveloped. • Double-stranded DNA genome. • Causes massive enlargement of infected cells. • Causes indefinite latent infection that can be reactivated occasionally.

  27. Transmission: • Fetus → transplacentally. • Newborn →1. during passage in the birth canal. 2. in the breast milk. • Adult →1. saliva. 2. sexually. 3. blood transfusion. 4. organ transplantation.

  28. Clinical forms • Normal host→ may cause: 1. latent infection. 2. infectious mononuleosis-like syndrome. 3. coronary heart disease. • Immunocompromised host→ pneumonia, retinitis, graft rejection or disseminated disease.

  29. Congenital infection→ may lead to: - abortion. - stillbirth. - cytomegalic inclusion disease → blindness, deafness, mental retardation, microencephaly, hepatosplenomegaly, jaundice, and purpura. • Newborn→ subclinical infection.

  30. Diagnosis: (1) Detection of intranuclear cytomegalic inclusions in tissues and desquamated cells in the urine. (2) PCR for detection of CMV-DNA. (3) Isolation of the virus from urine and throat washings. (4) Detection of IgM or rising titre of IgG in congenital infections.

  31. Varicella • Causative agent: • Varicella-Zoster virus (VZV). • Causes two distinct diseases: (1) Varicella → the primary disease. (2) Zoster → the recurrent form. • Belongs to the Herpesviruses family. • Enveloped, double-stranded DNA virus.

  32. Transmission: • In children and adults: (1) The respiratory route. (2) Contact with the lesions. • In neonates: (1) Transplacentally during pregnancy. (2) Through the birth canal during labor. (3) The respiratory route or contact with the lesions from the mother.

  33. Pathogenesis: • Incubation period is 14-21 days. • VZV multiplies in the mucosa of the respiratory tract → spreads via the blood to the skin causing the typical rash → evolves from papules to vesicles, pustules, and finally crusts → Rash starts on the trunk and spreads to he limbs and face →Recovery occurs without scar formation.

  34. The virus becomes latent in the dorsal root ganglia. • It is a highly contagious disease in children and can occur in epidemics. • The disease is mild in children but severe in adults

  35. Congenital varicella syndrome: • Maternal infection with VZV can lead to abortion, stillbirth, or congenital varicella syndrome. • Neonates may acquire the infection from the mother before or just after birth. • It is highly fatal. The main cause of death is pneumonia.

  36. Diagnosis: (1) Stained smears of scrapings or swabs of the base of vesicles shows multinucleated giant cells. (2) Detection of viral antigens or DNA in vesicular fluid, skin scrapings, or biopsy. (3) Detection of viral particles in the vesicular fluid by electron microscopy. (4) Isolation of the virus by cell culture. (5) Detection of virus-specific antibodies.

  37. Parvovirus B19 • The causative agent: • Parvovirus B19 is a small, nonenveloped virus. • The genome is single-stranded DNA. • Transmission: (1) The respiratory route. (2) Blood transfusion. (3) Transplacentally.

  38. Pathogenesis: • B19 virus attacks immature cells of the erythroid lineage causing their death. • The virus replicates in the bone marrow and fetal liver. • Red cell production is interrupted leading to chronic anemia. • B19 is found in the blood and respiratory secretions.

  39. Clinical forms: (1) Erythema infectiosum in children. (2) Aplastic crisis in patients with sickle cell anemia. (3) Severe anemia and persistent infection in immuncompromised patients. (4) Abortion, hydrops fetalis, and fetal death in the fetus.

  40. Diagnosis: (1) Detection of viral DNA by PCR. (2) Detection of virus-specific antibodies. (3) Detection of viral antigens in clinical samples. (4) Immunohistochemistry to detect viral antigens in the fetal tissues and bone marrow.

  41. Thank You

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