Spirochetes

• Order

  • Spirochaetales
• Families

  • Leptospiraceae
  • Spirochetaceae
• 2 families under the order Spirochaetales have different genus
• Leptospiraceae


  1 genus of interest to humans because it causes wide infections in humans: leptospira
• Spirochetaceae


  borrelia, treponema which are also the genera/genus of interest under this family
• General Morphology of Spirochetes

  • Long, slender, helically curved or helically coiled, gram (-) negative bacilli

  
• Helically coiled


  Body or cell wall of the organism is coiled or curved and it is long and slender (cell wall) being a long organism with its shaped is curved or coiled that that's why it is called a spiral organism
• Gram Negative Bacilli


  Appear pink or red under gram staining procedure or the Hucker's Method
• Staining techniques for tissue specimens and urine samples

  1. Levaditi Method/Staining for tissue specimens

  2. Fontana-Tribondeau for urine samples
• Unique morphologic features of spirochetes

  • Axial Fibril - serves as locomotor organelle
  • Outer Sheath - or the outer membrane/periplast
  • Insertion Disk/s
• The number of axial fibrils is directly proportional to the number of insertion disks present
• Axial Fibril


  Equivalent to flagella, also known as axial filaments or periplasmic flagella
• Insertion Disks


  Point of insertion of the endoflagella that wraps or extend throughout the body of a spirochete organism, located near the terminal portion of the spirochete cell wall
• Endoflagella


  Arrangement of wrapping around the coiled body of the spirochete gives a corkscrew-like winding motility
• Differentiation of Genera


  • Number of Axial Fibrils
  • Number of Insertion Disks
  • Biochemical or metabolic features
• Characteristics of Genera

  • Treponema
  • Borrelia
  • Leptospira
• Treponema

  Slender with tighter coils; pointed ends
• Borrelia

  Thicker with fewer and looser coils; pointed ends
• Leptospira

  Resembles borrelia but with hooked ends; coils are numerous also slender and tighter in appearance
• Leptospira is unique from the two other genera because it has hooked ends
• Treponema

  • Tighter coils because its coils are numerous and slender and has pointed ends
  • Fine spiral organism
  • Spirals are regular and angular (4-14)
  • Cannot grow in vitro
  • Animal Inoculation: Rabbit Testis
  • Cannot be seen in light microscopy, best seen with dark-field or phase-contrast
• Treponema species that colonize humans

  • Treponema pallidum subspecies pallidum (causative agent of venereal syphilis)
  • Treponema pallidum subspecies pertenue (causes Yaws)
  • Treponema carateum (causes Pinta)
  • Treponema pallidum subspecies endemicum (causes endemic syphilis)
• Other Treponemes as normal flora

  • T. vincentii
  • T. socranskii
  • T. oralis
  • T. denticola
  • T. pectinovorum
  • T. refringens
  • T. macrodentum
• Epidemiology: Entry into host

  • Penetrating the intact mucus membranes (for venereal syphilis)
  • Entering through breaks in the skin
• When the organism enters the system, it has predilection to blood so it causes spirochete organisms to become systemic in terms of the infection and therefore can cause Endarteritis and tissue destruction
• Syphilis


  Sexually transmitted disease caused by Treponema pallidum, characterized by 3 different stages
• Primary Stage

  Characterized by chancre formation - small, painless ulcer or lesion that grows in the genital area
• Chancre in venereal syphilis

  Hard, indurated to the genital or to the vaginal tissues and grows dry areas
• Chancre in Haemophilus ducreyi

  Soft and non-indurated
• Secondary Stage

  • Manifested by different vague signs and symptoms like fever, sore throat, lymphadenopathy, weight loss and rash
  • Rash appears on palms of hands and soles of feet
  • Other features include alopecia and condylomata lata
• Infection can become inactive or latent for 3-30 years before reactivating and entering the tertiary stage
• Tertiary Stage

  Involvement of Central Nervous System and Cardiovascular system, manifested by gumma formation and pronounced immunologic reaction
• Affected Area

  Moist areas in the vaginal and anal area
• Condylomata lata

  Moist lesion
• Chancre

  Dry lesion
• Syphilis infection

  1. Can become inactive or latent for 3-30 years

  2. Infection becomes active again, leading to tertiary stage
• Tertiary Stage

  • Involvement of Central Nervous System and Cardiovascular system
  • Manifested by gumma formation and generalized lymphadenopathy
• Penicillin


  Drug of choice for syphilis treatment, with a very low Minimum Inhibitory Concentration (MIC)
• Jarisch-Herxheimer Reaction


  • Systemic reaction after 24 hours of syphilis treatment, including fever, myalgia, headache, tachycardia, and increased respiratory rate
  • Caused by the sudden release of endotoxins from the spirochete organism
• Congenital Syphilis


  Transmitted from an infected mother to the baby during delivery