This document provides information on spirochetes, including their morphology, classification, pathogenic species, and details on specific diseases caused by them. It discusses the characteristics of Treponema pallidum and Borrelia burgdorferi, which cause syphilis and Lyme disease respectively. It also provides clinical manifestations, laboratory diagnosis, treatment and other relevant details about these diseases. Leptospira interrogans is described as the causative agent of Weil's disease or leptospirosis. The document contains detailed diagrams and explanations.

1. SPIROCHETES
DR. SUMESH KUMAR DASH
PG RESIDENT,
DEPARTMENT OF MICROBIOLOGY,
IMS & SUM HOSPITAL

2. BACKGROUND
◦ Gram negative, thin, flexible, elongated, motile,
spirally coiled helical bacilli.
◦ Speira, meaning coil
◦ Chaite, meaning hair
◦ However their cell wall differs from other GNB by
presence of endoflagella.
◦ Endoflagella do not protrude outside, but present
in the periplasmic space between peptidoglycan
layer and outer membrane
◦ These are responsible for various motility of
spirochetes such as:
◦ Flexion-extension type
◦ Corkscrew type rotatory movement
◦ Soft bending at right angle to mid point

3. CLASSIFICATION
◦ Most of the spirochetes are saprophytes.
◦ Only 3 of them are major human
pathogens
◦ Treponema
◦ Borrelia
◦ Leptospira
◦ The pathogenic spirochetes their mode of
transmission and spectrum of diseases
produced.
◦ They also differ in their morphological
properties.

4. MORPHOLOGY
◦ Treponema measure 6-14 um in length; posses 6-12 number of spirals. They
causes Syphilis, Endemic syphilis, Yaws, Pinta.
◦ Borrelia are larger in size (10-30 um in length), posses 3-10 number of spirals.
They cause various diseases such as relapsing fever, Lyme disease and Vincent's
angina.
◦ Leptospira measure 6-20 um in length. They posses numerous, tightly coiled
spirals and with hooked ends. They cause Weil's disease.

5. TREPONEMA
◦ Trepos means “To turn” ; Nema means “Thread”
◦ Thus these are the slender spirochetes with fine spirals and pointed end.
◦ Can’t grow in vitro (Culture media). [Exception of Koch’s Postulates].
◦ T.pallidum causes a sexually transmitted disease, called Syphilis
◦ Nonvenereal treponematoses are transmitted by nonsexual mode (direct
contact) and cause mainly cutaneous lesions.
◦ T.pertenue - Yaws
◦ T. endemicum – Endemic syphilis
◦ T.carateum - Pinta

6. SYPHILIS
◦ One of the oldest sexually transmitted disease (STD) known science 15th century.
◦ Caused by Treponema pallidum.
◦ Incubation period – 10 to 90days.
◦ Mode of transmission
◦ Sexual contact
◦ Direct contact
◦ Blood transfusion
◦ Transplacental – Congenital syphilis

7. CLINICAL MANIFESTATION
◦ Approximately 30% of people developed disease who sexually exposed to infective
partner.
◦ Patients suffer from this disease pass through 4 stages if left un treated:
 Primary
 Secondary
 Latent
 Tertiary (Late)

8. Primary Syphilis
◦ Primary (or hard) chancre: Singe painless hard
indurated ulcer; covered by thick exudate rich in
spirochetes. The most common sites are penis (Fig:
A), cervix or labia (Fig: F), and anal canal, rectum or
mouth (Fig: B,D,E).
◦ If acquired by non-venereal mode, then the primary
syphilis is presented as follows:
◦ Transmitted by direct contact, the primary chancre
is extragenital, usually on the fingers. (Fig: C)
◦ Transmitted by blood transfusion then chancre
does not occur

9. ◦ The chancre generally heals within 4-6 weeks (range 2-12 weeks), but lymphadenopathy
may persist for months.
◦ Regional (usually inguinal) lymphadenopathy appears within 1 week of onset of skin
lesions.
◦ Lymph nodes are painless firm, non-suppurative, and often bilateral

10. Secondary Syphilis
◦ Usually develops 6-12 weeks after the healing of primary lesion.
◦ Skin rashes (palms and soles)
◦ Condylomata lata: Mucocutaneous papules which coalesce to form large pink to grey
lesions in warm moist intertriginous areas such as perianal region, vulva, and scrotum.
◦ Mucous patches (superficial mucosal erosions)

11. Latent Syphilis
◦ Secondary lesions usually subside within 2-6 weeks, and the infection proceeds to latent
syphilis; which is characterized by absence of clinical manifestations of syphilis with
positive serological tests for syphilis.
◦ Latent syphilis may be early latent syphilis (occurs within first year after infection) and
late latent syphilis (occurs after the first year of infection)
◦ Patients are still infectious transmitting the infection either by bloodstream or in utero.
◦ Latent syphilis may have one of the following fates:
◦ Persistent lifelong infection (common)
◦ Development of late syphilis (rare)
◦ Spontaneous cure.

12. Late Syphilis
◦ Several decades after the initial infection, about one-third of untreated patients
develop tertiary syphilis.
◦ 5% develop gummatous lesions
◦ 10% develop cardiovascular lesions
◦ Remaining 10% develop neurosyphilis.

13. STAGE SYMPTOMS TIMELINE
Primary Painless sores called
chancre at the site of
inoculation or contact
of the pathogen
Begins from 3 or 4 weeks after
exposure
Secondary Rash and other systemic
symptoms
Begins from 4 to 8 weeks from
the onset of primary symptoms
Latent Asymptomatic Early and late latency period
varying about a year
Late Starting from benign
lesions, can damage the
cardiovascular and
central nervous system
Mostly after 8 to 10 years

14. LABORATORY DIAGNOSIS
◦ Microscopy
◦ Dark ground microscopy
◦ Direct IF staining for T. pallidum (DFA-TP)
◦ Silver impregnation method
◦ Culture: Not cultivable, maintained in rabbit testes
◦ Serology: (Antibody detection)
◦ Standard tests for syphilis: (Cardiolipin antigen)
◦ VDRL (Venereal disease research laboratory) test
◦ RPR (Rapid plasma reagin)
◦ TRUST (toluidine red unheated serum test)
◦ USR (Unheated serum reagin test)
◦ Specific test: (T.pallidum antigen)
◦ TPI (T.pallidum immobilization test)
◦ FTA-ABS (Fluorescent treponemal antibody absorption test)
◦ TPA (T.pallidum agglutination test)
◦ TPHA (T.pallidum hemagglutination test)
◦ TPPA (T pallidum particle agglutination test)
◦ Polymerase chain reaction (PCR)

15. VDRL
Principle: Precipitation (Slide flocculation test)
Procedure: 50 uL of patient's serum (heat inactivated) is
mixed with a drop of VDRL antigen on a concave slide,
which is then mixed by rotating the slide for 4 minutes
Result: Positive test (i.e. reactive) is indicated by formation
of medium to large clumps of antigen antibody
complexes; visualized by focusing the slide under
microscope (10x).
Uses:
◦ Cheaper
◦ Preferred as a screening test (e.g. antenatal screening)
◦ Detect antibody in CSF (Neurosyphilis)
◦ Monitor treatment response

16. RPR
◦ Rapid Plasma Reagin (RPR) RPR is another slide
flocculation test using disposable plastic cards
having clearly defined circles.
◦ It is similar to VDRL test with some differences
such as:
◦ RPR antigen has a prolonged shelf-life, therefore it
is preferred to test individual sample (less sample
load);
◦ Results can be read in naked eyes, without the need
of a microscope, as the clumps formed are bigger
in size
◦ It can only be used for detecting antibodies in blood
not in CSF
◦ It is more expensive than VDRL.

17. ADVANTAGES & DISADVANTAGES OF STANDARD
TESTS
ADVANTAGES
◦ Monitor the to the response to treatment
◦ Detect Neurosyphilis
◦ Reagin antibody becomes detectable 7-10 days after the appearance of primary chancre (or 3-5 weeks
after acquiring the infection)
◦ The sensitivity of nontreponemal tests varies from 78 to 85% in primary stage, 100% in secondary
stage, 71-73% in late stage and the specificity is around 98-99%.
DISADVANTAGES
◦ Biological false-positive (BFP) reactions: The incidence of BFP is generally 1-2%. This is because
reagin antibodies may also be found in patients with unrelated diseases such as lepromatous leprosy,
relapsing fever, malaria, viral hepatitis, HIV, pregnancy and IV drug abusers
◦ Prozone phenomena: If antibody titer in patient's sera is high, it may lead to false negative result hence
it is essential to test sera in dilutions
◦ Sensitivity of non-treponemal tests is low in late stage of syphilis.

18. TREATMENT
◦ Penicillin is the drug of choice for all the stages of syphilis
◦ Alternative drug is used in patients with penicillin allergy: Tetracycline is recommended
EVALUATION AFTER TREATMENT
◦ Non-treponemal test, such as VDRIL and RPR are preferred.
◦ VDRL has to be done at 3 months' intervals for at least 1 year.
PREVENTION
◦ Treatment of cases and contacts (sexual partners)
◦ Education about safe sex practices
◦ Prophylactic use of barrier contraceptive methods.

19. CONGENITAL SYPHILIS
◦ May Occur at any stage of pregnancy, but fetal damage occurs only after fourth month of gestation.
◦ Untreated cases of early maternal syphilis are at higher risk.
◦ Antenatal screening and treatment of positive cases during pregnancy may prevent congenital syphilis.
◦ Earliest manifestations : Occur within 2 years of age and is infectious
◦ They suffer from rhinitis, mucocutaneous lesions, bone changes, hepatosplenomegaly and
lymphadenopathy.
◦ Late congenital syphilis: Occurs after 2 years and is non-infectious.
◦ It is characterized by interstitial keratitis, eighth- nerve deafness, bilateral knee effusions.
◦ Residual stigmata may remain for long time such as:
◦ Hutchinson's teeth (notched central incisors)
◦ Mulberry molars (molars with poorly developed cusps)
◦ Saddle nose
◦ Saber shins.

20. RHINITIS HUTCHINSON'S TEETH INTERSTITIAL KERATITIS
MULBERRY MOLARS
SADDLE NOSE SABER SHINS

21. BORRELIOSIS
◦ Borrelia are larger in size (10-30 um in length), posses 3-10 number of spirals.
◦ Most of the species are commensals on the buccal and genital mucosa.
◦ Few are pathogenic to human
◦ B. recurrentis - Relapsing fever
◦ B. burgdorferia - Lyme disease
◦ B. vincentii - Vincent's angina.

22. Relapsing Fever
CHARACTERISTIC EPIDEMIC RF ENDEMIC RF
CASETIVE AGENT B.recurrentis B.duttonii, B.hermsii, B.turicatae
MODE OF TERANSMITION Louse Ticks
ROUT OF ENTRY Crushing or Scratching Bite
C/F Recurrent febrile episode (Fever: 3-4days;Afebrile: 4-14days), Petechia,
Some neurological feature (Seizure, Paraplegia, Meningitis, Psychosis etc.
)
LAB DIAGONOSIS Microscopy, Smear (Giemsa stain), Culture, Serology (ELISA,IFA etc.)
TREATMENT Doxycycline or Erythromycin
RF characteristic by recurrent episodes of fever and nonspecific symptoms following
exposure to insect vector carrying Borrelia species.

23. Lyme Disease
CHARACTERISTIC SUMMERY
OTHER NAME Lyme borreliosis
AGENT Borrelia burgdorferi
RESERVOIRS Rodent & Deer
TRANSMITTED BY Tick
CLINICAL MANIFESTATIONS (3 Stages) • Early localized infection: After an incubation period of 3-32 days, an
annular maculopapular lesion develops at the site of the tick bite
called erythema migrans, commonly involving thigh and groin.
• Early disseminated infection: Spreads hematogenously, resulting in
secondary annular skin lesions, arthralgia, malaise and neurological
abnormalities.
• Late persistent infection (Lyme arthritis): About 60% patients
develop arthritis of large joints (e.g. knees), lasting for months.
LABORATORY DIAGNOSIS Culture, Molecular methods, Serology
TREATMENT Doxycycline (Adult), Amoxicillin (Children)

24. Vincent's Angina
CHARACTERISTIC SUMMERY
DEFINITION Acute necrotizing ulcerative gingivitis
OTHER NAME Trench mouth or Vincent's stomatitis
AGENT Borrelia vincentii
CLINICAL MANIFESTATIONS • Gingivitis with sudden onset of painful bleeding gums
• Foul breath
• Bad taste
• Gingival mucosa becomes ulcerated and may be covered by gray
"pseudomembrane" resembling diphtheria, but peels off easily
LABORATORY DIAGNOSIS Microscopic smear
TREATMENT Treatment consists of debridement and antibiotics(Metronidazole
plus Penicillin).
PROGNOSIS Mortality is high if not treated

25. LEPTOSPIRA
◦ Leptospira is antigenically complex; comprises of two species:
◦ L. interrogans: Pathogenic to man.
◦ L. biflexa: Saprophyte and not pathogenic to man.

26. Leptospirosis
◦ Leptospira interrogans causes leptospirosis or Weil's disease
◦ It is a zoonotic disease
MODE OF TRANSMISSION: Direct human-to-human transmission does not occur.
◦ Indirect contact with water, moist soil and wet surfaces contaminated with animal urine or
◦ Direct contact with urine and products of parturition, placenta of infected animals.
SOURCE: Rats, dogs, cattle and pigs.
SEASONALITY: Leptospirosis is more common in rainy and post monsoon period.

27. RISK FACTORS: Lower socioeconomic status
◦ Urban and rural slum areas
◦ Rainfall and floods
◦ Occupational exposure: Agricultural workers (e.g. rice field planters),
fishermen, sewer workers
3R’s: Rodents
Rainfall
Rice field Incidence

28. Pathogenesis
There are two distinct phases of pathogenesis following leptospiral infection:
First phase (septicemic phase):
◦ After entering through the mucosa (conjunctival or oral) or abraded skin, L. interrogans
spill over to the bloodstream and then disseminate hematogenously to various organs
including brain, liver, lung, heart and kidney.
◦ Vascular damage: Spirochetes can invasion of tissues ,walls of capillaries and vessels due
to active motility and release of hyaluronidase.
Second phase (immune phase):
◦ As antibodies develop, spirochetes disappear from the blood.
◦ Antigen antibody complexes are deposited in various organs
◦ Renal colonization: Bacilli become adherent to the proximal renal tubular brush border
and are excreted in urine.

29. Clinical Manifestations
The incubation period is around 10 (1 to 30) days. In general, the manifestations can be
divided into two distinct clinical syndromes
1. Mild anicteric febrile illness
2. Weil's disease (Hepato-renal-hemorrhagic syndrome)

30. Laboratory diagnosis
SPECIMENS: CSF, Blood and Urine
MICROSCOPY
Dark ground microscope or silver impregnation staining
ISOLATION:
◦ Culture condition: 30°C for 4-6 weeks
◦ Medium: EMJH medium, Korthof's and Fletcher's media.
SEROLOGY FOR ANTIBODY DETECTION
◦ Genus specific tests: Macroscopic slide agglutination test, Latex
agglutination test, ELISA, ICT
◦ Serovar specific test: Microscopic agglutination test
MOLECULAR METHODS: PCR
NONSPECIFIC FINDINGS: Altered LFT, RFT
◦

31. TREATMENT
◦ Mild leptospirosis should be treated with oral doxycycline (100 mg twice a day for 7 days).
◦ Amoxicillin can be given alternatively
◦ Severe leptospirosis: Penicillin is the drug of choice (1.5 million units IV, four times a day for 7 days)
◦ Alternatives being ceftriaxone or cefotaxime.
PREVENTION
Vaccine
◦ SPIROLEPT manufactured by Sanofi-Pasteur is available for subcutaneous injection as two doses at 15 days
interval, with the third dose 4-6 months after the first dose, followed by biannual revaccination.
General Measures
◦ Chemoprophylaxis with doxycycline is recommended for high risk individual
◦ Rodent control
◦ Avoidance of swimming in contaminated places
◦ Health education