Spirochetes Question And Answers

Spirochaetes Long Essays

Question 1. Laboratory diagnosis of syphilis
Serological tests for syphilis

1. Microscopy

  • It is useful in primary and secondary syphilis
  • Direct fluorescent antibody test is used for T. pal¬lidum
  • In this method acetone fixed smear is subjected to fluorescent tagged anti-T. pallidum antiserum

2. Serological tests

  • Tests for antibodies reacting with cardiolipin anti¬gen
    • Standard tests for syphilis
      • Wassermann test
  • It is a complement fixation test

Serological tests for syphilis Method:

  • Patient’s serum is inactivated by heating at 56s C for 30 minutes
  • Incubated with cardiolipin antigen and guinea pig antigen at 37° C for 1 hour
  • Indicator is added to detect presence or absence or complement
  • 0.15 ml of inactivated serum is taken in three test tubes containing 0.05, 0.025 and 0.0125 ml of freshly prepared antigen dilution
  • Tubes are shaken on Kahn’s shaken and examined

Serological tests for syphilis Interpretation:

    • If hemolysis does not occurs, it indicates that the complement is utilized
    • This is positive Wassmann’s reaction
    • It hemolysis takes place, it indicates the comple¬ment is not been utilized in tire primary reaction but utilized by the indicator system
    • Kahn test
    • It is tube flocculation test
    • Negative test shows uniform opalescence
    • Positive test shows floccules
    • VDRL test
    • In this test the inactivated serum is mixed with cardiolipin antigen on a special slide and rotated for 4 minutes
    • Uniform distribution of crystals in the drop indi¬cates tire serum is non reacting
    • Formation of clumps indicates it is reactive
  • Tests for antibodies reacting with group specific treponemal antigen
    • Reiter protein complement fixation test
      • In this method, lipopolysaccharide protein complex antigen derived from the cultivable Reiter’s stain is used
      • It is less sensitive
  • Tests for specific antibodies to pathogenic tre¬ponema
    • Treponema pallidum immobilization test
      • It employs live T. pallidum
      • The test serum is mixed with actively motile Nichol’s strain of T. pallidum and incubated anaerobically
      • If antibodies are present, the treponemas are immobilised

Read And Learn More: Microbiology Question and Answers

    • Fluorescent treponemal antibody absorption
      • Test serum is preabsorbed with an extract of non pathogenic treponemas to remove group specific antigens
      • It detects IgM and IgG
      • It is the earliest test to become positive
    • Microhaemagglutination test for treponema pallidum
      • T. pallidum antigen is coated onto the surface of red cells
      • Tanned sheep RBCs are sensitized with an extract of T. pallidum
      • When these sensitized erythrocytes are mixed with patient’s serum containing anti¬bodies, the erythrocytes clump together
    • Enzyme immunoassay
      • They have been developed using T. pallidum antigens and are available commercially

Spirochaetes Short Question And Answers

Question 1. VDRL test

  • Venereal Disease Research Laboratory test is the most widely used serological test for diagnosis of syphilis
  • It is simple and more rapid test which gives more quantitative results
  • It requires only small amount of serum and is sensitive

VDRL test Procedure:

  • In this test the inactivated serum is mixed with cardi- olipin antigen on a special slide and rotated for 4 min¬utes
  • Uniform distribution of crystals in the drop indicates the serum is non reacting
  • Formation of clumps indicates it is reactive
  • By testing serial dilutions, the antibody titre can be determined

Question 2. Vincent’s angina

  • Vincent’s angina is a painful condition of the throat characvterized by local ulceration of the tonsils, mouth and pharynx
  • Vincent’s bacilli is the causative organism
  • It may occur as an acute illness with diffuse involve¬ment of tissue or as chronic illness consisting of ulcera¬tion of tonsil
  • It is insidious in onset with less fever and less discom¬fort
  • Membrane which usually forms over the tonsil can be easily removed revealing irregular ulcer on the tonsil

Question 3. Borrelia vincentii

  • It is a motile spirochaete which is a normal mouth commensal but a potential pathogen.
  • Under predisposing conditions such as malnutrition (or) viral infections it gives rise to ulcerative gin¬givostomatitis or oropharyngitis (Vincent’s angina).
  • Borrelia vincenti in association with fusiform bacilli causes an infection known as fusospirochetosis.
  • Diagnosis may be made by demonstrating spirochaetes and fusiform bacilli in stained smears of exudates from the lesions.
  • Cultivation is difficult but can be done in enriched me¬dia anaerobically.
  • Penicillin and metronidazole are effective in treatment.

Question 4. Congenital syphilis

In congenital syphilis the infection is transmitted from mother to foetus transplacentally.

Congenital syphilis Clinical Features:

  • Hutchinson’s traid
    • Hyperplasia of the incisor and molar teeth
    • Interstitial keratitis
    • Eight nerve deafness.
  • Frontal bossing
  • Saddle nose
  • High palatal arch
  • Poorly developed maxillae
  • Irregular thicknening of clavicle
  • Enlarged liver and spleen
  • Diagnosis may be done by demonstrating spirochetes in lesions under dark ground microscope.
  • IgM FTA – ABS test, the modification of indirect im-mune fluorescence test is useful for diagnosis of con-genital syphilis and distinguishing from seropositivity due to passively transferred maternal antibodies

Spirochaetes Viva Voce

  1. Techoic acid of cell wall of staphylococci facilitates adhesion of cocci to host cell
  2. ASO test is used for diagnosis of rheumatic fever
  3. Pneumococci gives draughtsman or carom coin ap-pearance on blood agar
  4. Modified Thayer Martin, selective media is used for meningococci
  5. Corynbacterium diphtheria shows Chinese letter or cuneiform arrangement
  6. DTP vaccine consists of diphtheria toxoid, tetanus toxoid and pertussis vaccine
  7. Bacillus coreus causes food poisoning
  8. Clostridium contains peritrichate flagella for motility
  9. Widal test is used for diagnosis of typhoid fever
  10. Dreyer’s tube and Felix tube are used in widal test
  11. Food poisoning is caused by any salmonella except salmonella typhi
  12. Yersinia pestis is causative agent of plaque or black death
  13. Trepnema pallidum is causative agent for syphilis
  14. VDRL test is used for syphilis
  15. Actinomycetes gives sun ray appearance on culture
  16. H pyroli causes peptic ulcer

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