Microbiology

SPIROCHETES I: TREPONEMA
December 04, 2020 | Topic 19
0
Overview Ø In whole blood or plasma stored at 4 C à
remain viable for at least 24 hours
I. Treponema species Ø Non-pathogenic or saprophytic strains (Reiter
II. Treponema pallidum strain)
III. Treponema pallidum endemicum • Anaerobic culture in vitro à 30 hours
IV. Treponema pallidum pertenue doubling time
V. Treponema carateum • Defined medium containing amino acids,
vitamins, minerals, salts, and serum
albumin
TREPONEMA SPECIES
GROWTH
Ø Treponema pallidum
• T. pallidum subspecies pallidum Ø Slow replication à 30-33 hours doubling time
(Syphilis) Ø In presence of reducing substances à remain
0
• T. pallidum subspecies endemicum motile for 3-6 days at 25 C
(Bejel)
OTHER CHARACTERISTICS
• T. pallidum subspecies pertenue (Yaws)
Ø Treponema carateum (Pinta)
Ø Rapidly killed or immobilized by
GENERAL CHARACTERISTICS • Drying
0
• High temperature (42 C)
Ø Gram-negative, actively motile • Trivalent arsenical, mercury and bismuth
• Slender spirals regularly spaced at a Ø Metabolic inactivity and slow multiplication rate
distance of 1 um from one another à of organism à slow rate of killing using penicillin
seen only with immunofluorescent or
darkfield microscope VIRULENCE FACTORS
Ø With pointed tapering ends
Ø Stain with difficulty except with Giemsa’s or
silver stain Ø Outer membrane proteins covalently bound
Ø No tricarboxylic acid cycle in the bacteria à to lipids
failure to grow in vitro • Lipids: keep the proteins inaccessible to
• No dependent on host cells for all antibodies
purines, pyrimidines, and amino acids • Proteins: promote adherence to host
cell
Ø Hyaluronidase: facilitates perivascular
STRUCTURE
infiltration; enhance invasiveness
Ø Coating of fibronectin: protect against
Ø Outer sheath: glycosaminoglycan coating phagocytosis
(mucoid layer) Ø Species-specific antigen on cell surface:
Ø Outer membrane: inside the sheath; contains evasion of immune system
peptidoglycan; maintain structural integrity
Ø Endoflagella or axial filaments: within PATHOGENESIS
periplasmic space; encased by outer membrane
Ø Inner or cytoplasmic membrane: within endo- 1) Adherence to skin or mucosal membranes à
flagella; osmotic stability; cover protoplasmic produce hyaluronidase à promote tissue
cylinder invasion
Ø Cytoplasmic tubules (body fibrils): near inner 2) Organism becomes coated with host fibronectin
membrane à protect against phagocytosis and immune
recognition
CULTURE
• Treponemes spread to other skin tests
and to other organs hematogenously
Ø Pathogenic T. pallidum never been cultured soon after infection
continuously on artificial • Skin lesions of primary syphilis à
• Usually cultured in testes of rabbits represent the primary site of initial
Ø Microaerophilic (1-4% oxygen) replication

Irelia: The Blade Dancer 1

 Microbiology
SPIROCHETES I: TREPONEMA
December 04, 2020 | Topic 19

PHASES OF DISEASE ACQUIRED SYPHILIS

1) Primary phase PRIMARY STAGE

• Chancres at the site of penetration à Ø Chancre: painless, ulcerated skin lesion at the
primary site of initial replication site of inoculation; 10-90 days after initial
• Endarteritis and periarteritis; infection
polymorphonuclears and macrophages Ø Painless LAD 1-2 weeks after appearance of
2) Secondary phase chancre
• (+) clinical signs of disseminated Ø Spontaneous healing of the chancre within 3-6
disease weeks à does not indicate a cure
• skin lesions Ø Highly infectious
3) Late phase Ø Initial infection :10-90 days à papule à
• Systemic spread à virtually all tissues painless ulcer with raised border (chancre) à
involved spontaneous healing within 2 months
• Abundant spirochetes present in the
chancre à disseminate via lymphatics
or blood stream
• Secondary lesions appear 2-10 weeks
after resolution of primary lesion

SECONDARY STAGE
Ø Clinical evidence of disseminated disease
Ø “Flu-like” syndrome + lymphadenopathy
Ø Some with alopecia areata
Ø Lesions: highly infectious
1) Generalized mucocutaneous rash
• Red maculopapular rash anywhere in
the body including the hands and feet
2) Condylomata lata
• Moist pale papules in anogenital region,
axillas, and mouth
IMMUNITY Ø Other manifestations
• Syphilic meningitis
Ø Tissue destruction primarily due to host’s • Chorioenteritis
immune response to infection • Hepatitis
• Nephritis (immune complex type)
MODE OF TRANSMISSION • Periotitis
Ø Lesions also rich in spirochetes à highly
1) Sexual contact during primary stage infectious
2) Skin contact with disseminated rash during Ø Rash and symptoms gradually resolve
secondary stage spontaneously within 6-8 months of infection
3) Transfusion or contaminated blood • 30% complete cure without treatment
4) In utero from infected mother • Others become dormant in liver and
spleen
Ø Local multiplication at initial site of entry
a) Infectious lesions on the skin mucous LATENT STAGE
membranes of genitalia Ø Clinically inactive stage but with (+) serologic
b) 10-20%: initial lesion intra-rectal, perianal, or tests
oral Ø 30% of untreated infection

TERTIARY (LATE) STAGE

Ø 1/3 of untreated patients
Ø Activation of dormant treponemes 3-30 years
later in untreated cases

Irelia: The Blade Dancer 2

 Microbiology
SPIROCHETES I: TREPONEMA
December 04, 2020 | Topic 19
Ø Diffuse, chronic inflammation Table 1. Types of diagnostic test
Ø Characteristics Diagnostic Method of Examination
1) Granulomatous lesions (gummas) in skin, Test
bones, and liver Microscopy o Darkfield
2) Degenerative CNS changes o Direct fluorescent antibody
(neurosyphilis): meningovascular syphilis, staining
paresis, tabesis dorsalis Culture Not available
3) CV lesions: aortitis, aortic aneurysm, aortic serology o Nontreponemal tests
valve insufficiency ü Venereal Disease Research
Laboratory (VDRL)
ü Rapid Plasma Regin Test
(RPR)
ü Unheated Serum Reagin
(USR) Test
ü Toluidine Red Unheated
Serum Test (TRUST)
o Treponemal Tests
ü Fluorescent Treponemal
Antibody
ü Treponema pallidum Particle
ARGYLL ROBERTSON PUPIL (LIGHT-NEAR Agglutination (TP-PA)
DISSOCIATION) ü Enzyme immunoassay
Ø Bilateral small pupils
Ø (+) constriction on accommodation SPECIMEN
Ø (+) constriction when exposed to bright light Ø Tissue fluid from early surface lesions; blood
serum for serology

DARK FIELD EXAMINATION

Ø Typical motile spirochetes
Ø Exudates from skin lesion; primary, secondary
and congenital syphilis

IMMUNOFLUORESCENCE
Ø Fluorescent spirochetes: more useful

NUCLEIC ACID-BASED TESTS (PCR)

Ø For detecting T. pallidum in:
a) Genital lesions
b) Infant blood
c) CSF
CONGENITAL SYPHILIS
Ø Screening tests; not sensitive in early syphilis
th th Ø Antigens: measured amounts of cardiolipin (from
Ø Transmission: beginning in the 10 – 15
beef heart), cholesterol & purified lecithin
weeks AOG
Ø Antibodies: syphilitic IgG and IgM reaginic
Ø Early congenital: rhinitis + desquamating
antibodies
maculopapular rash
Ø VDRL ((Venereal Dse. Research Lab.):
Ø Late congenital: interstitial keratitis,
standardized for use on CSF
Hutchinson’s teeth, saddle nose, mulberry
Ø USR (Unheated Serum Reagin) test
molars, periostitis, CNS anomalies, saber shins,
Ø RPR (Rapid Plasma Reagin)
symmetrical swelling (Clutton’s joints)
Ø Only the VDRL test should be used to test
CSF from patients with neurosyphilis
Ø Sensitivity
• 70% - 85% for primary disease
• 100% for secondary disease

Irelia: The Blade Dancer 3

 Microbiology
SPIROCHETES I: TREPONEMA
December 04, 2020 | Topic 19
• 70-75% for late syphilis • Remain elevated in infants with
Ø Specificity: 98-99% congenital syphilis
Ø (+) after 2-3 weeks of untreated syphilis à revert
to negative in 6-18 months and by 3 years after
effective treatment
Ø (+) in high titer in secondary syphilis
Ø if (+) late after treatment à ineffective treatment

SEROLOGIC TESTS: TREPONEMAL TESTS

Ø Measure antibodies vs. T. pallidum antigens
Ø Used to confirm if a (+) result from
nontreponemal test is truly (+) or falsely (+)
Ø Serial dilution of serum not done
Ø Report as reactive or non-reactive
Ø T. pallidum Particle Agglutination (TP-PA) –
most widely used in U.S.
Ø T. pallidum Hemagglutination (TPHA) & micro-
hemagglutination (MHA-TP)
Ø Fluorescent Treponemal Antibody Absorbed
(FTA-ABS): most commonly used
Ø If (+) IgM FTA in blood of newborn à (+) in utero
infection
Ø Not helpful in diagnosis of neurosyphilis but if (-),
exclude neurosyphilis

Conditions with false (+) Conditions with false (+)

nontreponemal tests treponemal tests
o Viral infection o Pyoderma
o Rheumatoid arthritis o Rheumatoid arthritis
o SLE o SLE TREATMENT
o Acute or chronic illness o Psoriasis
o Pregnancy o Crural ulceration
o Recent immunization o Skin neoplasm PENICILLIN
Ø Drug of choice
o Drug addiction o Drug addiction
Ø Long-acting benzathine PEN for early stages
o Leprosy o Mycoses
Ø Penicillin G for congenital and late syphilis (only
o Malaria o Lyme disease
penicillin for neurosyphilis and pregnant patients)
o Multiple blood o Acne vulgaris
Ø Alternatives: tetracycline and doxycycline
transfusions
Ø No available vaccine
Ø Diagnosis of neurosyphilis and congenital
syphilis on clinical symptoms and laboratory TREPONEMA PALLIDUM ENDEMICUM (BEJEL)
findings
• VDRL test on CSF is highly specific but Ø Endemic syphilis or Bejel
not sensitive à (+) test does not rule Ø Distribution: Chiefly Africa; also Middle East,
out Southeast Asia, and elsewhere; usually children
• (+) FTA-ABS CSF test consistent with Ø Mode of transmission: person-to-person
neurosyphilis but not diagnostic (contaminated eating utensils)
Ø (+) Serologic test results in infants may Ø Lesions
represent passive transfer of antibodies from • Secondary: papules and mucosal
mothers patches
• measure antibody titers in sera for 6 • Late: gummas of skin, bones, and
months à antibody titers in non- nasopharynx
infected decrease to undetectable Ø Treatment
levels within 3 months of birth • Benzathine penicillin

Irelia: The Blade Dancer 4

 Microbiology
SPIROCHETES I: TREPONEMA
December 04, 2020 | Topic 19
• Children <10 year old: 600,000
benzathine penicillin IM
• >10 year old: 1.2 million IM
• Single dose azithromycin 30 mg/kg not
to exceed 2 grams (WHO
recommendation)

TREPONEMA PALLIDUM PERTENUE (YAWS)

Ø Endemic among children (<15 y/o) in humid, hot

tropical countries
Ø MOT: direct contact with infected skin lesions
Ø Primary lesion: ulcerating papule, usu. on arms
or legs
Ø Late destructive lesions of the skin, LN, and
bones à scar formation common
Ø (+) cross-immunity with syphilis
Ø Diagnosis & treatment same as syphilis
Ø Dramatic improvement with PEN

TREPONEMA CARATEUM (PINTA)

Ø Endemic in all age groups in Mexico, Central &

South America, the Philippines, and some areas
of the Pacific
Ø Restricted to dark-skinned races
Ø MOT: direct contact OR through flies or gnats
Ø Primary lesion: non-ulcerating, small pruritic
papule on exposed areas
• Months later à flat, hyperpigmented
lesions on skin à depigmentation and
hyperkeratosis years after

REFERENCE
th
• Jawetz’ Medical Microbiology 28
Edition
• Proctor’s PowerPoint presentation
• 2021 Transcript
• Beshywap Transcript

Irelia: The Blade Dancer 5

 MICROBIOLOGY
SPIROCHETES I (TREPONEMA)
Doc Bartolome | December 4, 2020

→ generation time: 30-33 hours doubling time

TREPONEMA
● In presence of reducing substances
Family: Spirochaetaceae → remain motile for 3 – 6 days at 25°C
Genus: Treponema → incubation period:10-90 days

Treponema pallidum
● T. pallidum subspecies pallidum (Syphilis)/ Great Pox From Jawetz:
● T. pallidum subspecies endemicum (Bejel)
● T. pallidum subspecies pertenue (Yaws) In proper suspending fluids and in the presence of reducing
Treponema carateum (Pinta) substances, T. pallidum may remain motile for 3-6 days at
25C. In whole blood or plasma stored at 4C, organisms
TREPONEMA PALLIDUM remain viable for at least 24 hours, which is of potential
importance in blood transfusions.
GENERAL CHARACTERISTICS
● Gram negative, actively motile
● Slender spirals regularly spaced at a distance of 1 μm from OTHER CHARACTERISTICS
one another
● Rapidly killed or immobilized by
▪ Seen only with immunofluorescent stain or darkfield
o Drying
microscope
o High temperature (42°C)
● With pointed tapering ends with regular intervals
o Trivalent arsenical, mercury & bismuth
● Stain with difficulty except with Giemsa’s or silver stain
● Metabolic inactivity + slow multiplication rate of organism 
● No tricarboxylic acid cycle in the bacteria  failure to grow
slow rate of killing using penicillin
in vitro
▪ Dependent on host cells for all purines, pyrimidines and
VIRULENCE FACTORS:
most amino acids

STRUCTURE
● Outer sheath: glycosaminoglycan coating (mucoid layer),
encloses with axial fibrils (originates from insertion pores at
both poles of cell)
● Outer membrane – inside the sheath; contains
peptidoglycan; maintain structural integrity
● Endoflagella or axial filaments – within periplasmic space;
encased by outer membrane, for rotation and flexion
● Inner or cytoplasmic membrane – within endo-flagella;
PATHOGENESIS
provide osmotic stability; cover protoplasmic cylinder
● Cytoplasmic tubules (body fibrils) – near inner membrane 1. Adherence to skin or mucosal membranes  produce
● Absence of TCA hyaluronidase  promote tissue invasion
2. Organism becomes coated with host fibronectin  protect
CULTURE: against phagocytosis and immune recognition
● Pathogenic T. pallidum never been cultured continuously ● Treponemes spread to other skin sites & to other organs
on artificial media hematogenously soon after infection
▪ Usually cultured in testes of rabbits ● Skin lesions of primary syphilis  represent the primary
▪ inoculation in anterior chamber of the eye site of initial replication
● Microaerophilic (1% - 4% oxygen) ● Most frequent inoculation body site: external genitalia
● In whole blood or plasma stored at 40°C ● Most prominent histopathologic findings: Arteritis and
→ remain viable for at least 24 hours periarteritis
● Non-pathogenic or saprophytic strains (Reiter strain)
▪ Anaerobic culture in vitro PHASES OF DISEASE
→ 30 hours doubling time 1. Primary phase (Acquired syphilis)
▪ Defined medium containing amino acids, vitamins, ● Chancres at site of penetration  primary site of initial
minerals, salts and serum albumin replication, painless
● Endarteritis and periarteritis; PMNs & macrophages
GROWTH 2. Secondary Phase
● Slow replication ● (+) clinical signs of disseminated disease

1 TRANSCRIBERS: AAmul, MD, AmaraMD, Alpha17

 MICROBIOLOGY
SPIROCHETES I (TREPONEMA)
Doc Bartolome | December 4, 2020

● Skin lesions ● Heals spontaneously

3. Late Phase ● Initial infection – 10-90 days  papule  painless ulcer
● Systemic spread  virtually all tissues involved with raised border (chancre)  spontaneous healing within
2 months
o Abundant spirochetes present in the chancre 
disseminate via lymphatics or blood stream
o Secondary lesions appear 2 – 10 weeks after resolution
of primary lesion

SECONDARY STAGE
● Clinical evidence of disseminated disease
● “Flu-like” syndrome + lymphadenopathy
● Some with alopecia areata
● Lesions: highly infectious
1. Generalized mucocutaneous rash
o Red maculopapular rash anywhere in the body
including the hands & feet
2. Condylomata lata
o Moist, pale papules in anogenital region, axillas, and
mouth
IMMUNITY ● Other manifestations:
o Syphilitic meningitis
● Tissue destruction primarily due to host’s immune
o Chorioretinitis
response to infection
o Hepatitis
o Nephritis (immune complex type)
From Jawetz: o Periostitis
● Lesions also rich in spirochetes  highly infectious
A person with active or latent syphilis appears to be resistant ● Rash & symptoms gradually resolve spontaneously within 6
to superinfection with T. pallidum. However, if early syphilis to 8 months of infection
is treated adequately and the infection is eradicated, the o 30% complete cure without Tx
individual again becomes fully susceptible. The various o Others become dormant in liver and spleen
immune responses usually fail to eradicate the infection or o resolve spontaneously but still highly infectious
arrest its progression.
LATENT STAGE
● Clinically inactive stage but with (+) serologic tests
CLINICAL MANIFESTATIONS ● 30% of untreated infection
● MOT: ● Patient is asymptomatic but in serologic test they are
1. Sexual contact during primary stage positive this occurs when the patient is untreated
2. Skin contact with disseminated rash during secondary ● There is activation of the dormancy: 2 consequences
stage o reverse back to secondary stager or
3. Transfusion of contaminated blood o progress to tertiary stage
4. In utero from infected mother
● Local multiplication at initial site of entry TERTIARY (LATE) STAGE
1. Infectious lesions on the skin or mucous membranes of ● 1/3 of untreated patients
genitalia ● Activation of dormant treponemes 3 – 30 years later in
2. 10% - 20%; initial lesion intra-rectal, perianal, or oral untreated cases
● Some spread to nearby LN  blood ● Diffuse, chronic inflammation
● Characteristics:
ACQUIRED SYPHILIS 1. Granulomatous lesions (gummas) in skin, bones, and
PRIMARY STAGE liver
● Hard Chancre: painless, ulcerated skin lesion at the site of 2. Degenerative CNS changes (neurosyphilis) –
inoculation; 10-90 days after initial infection meningovascular SY, paresis, tabes dorsalis
● Painless LAD 1 – 2 weeks after appearance of chancre 3. CV lesions – aortitis, aortic aneurysm, aortic valve
● Spontaneous healing of the chancre within 3 to 6 weeks  insufficiency
does not indicate a cure
● Highly infectious

2 TRANSCRIBERS: AAmul, MD, AmaraMD, Alpha17

 MICROBIOLOGY
SPIROCHETES I (TREPONEMA)
Doc Bartolome | December 4, 2020

● Late congenital: interstitial keratitis, Hutchinson’s teeth,

saddle nose, mulberry molars, periostitis, CNS anomalies,
saber shins, symmetrical joint swelling (Clutton’s joints)
● Most distressing and dangerous form of syphilis
● Results from transplacental infection (in utero infection)

DIAGNOSIS

Argyll Robertson Pupil (Light-Near Dissociation)

Bilateral small pupils
(+) constriction on accommodation
(-) constriction when exposed to bright light

❖ Specimen: tissue fluid from early surface lesions; blood

serum for serology
❖ Dark-Field Examination
● Typical motile spirochetes
● Exudates from skin lesion; primary, secondary and
congenital syphilis
❖ Immunofluorescence
● Fluorescent spirochetes; more useful
❖ Nucleic Acid-Based Tests (PCR):
● For detecting T. pallidum in:
1. Genital lesions
2. Infant blood
3. CSF

From Jawetz: SEROLOGIC TESTS

NONTREPONEMAL TESTS
An infected person may remain contagious for 3-5 years
● Screening tests; not sensitive in early syphilis
during “early” syphilis. “Late” syphilis, of more than 5 years
● Antigens: measured amounts of cardiolipin (from beef
duration, is usually not contagious. Consequently, control
heart), cholesterol & purified lecithin
measures depend on:
● Antibodies: syphilitic IgG and IgM reaginic antibodies
1. prompt and adequate treatment of all discovered
● VDRL ((Venereal Dse. Research Lab.) – standardized for
cases
use on CSF
2. follow-up on sources of infection and contacts so
● USR (Unheated Serum Reagin) test
that they can be treated
● RPR (Rapid Plasma Reagin)
3. safe sex with condoms
● Only the VDRL test should be used to test CSF from
patients with neurosyphilis
CONGENITAL SYPHILIS ● Sensitivity: 70% - 85% for primary disease
100% for secondary disease
● Transmission: beginning in the 10th – 15th weeks AOG
70% - 75% for late syphilis
● Early congenital:fetal death, miscarriage or stillbirth, rhinitis
● Specificity: 98% - 99%
+ desquamating maculopapular rash

3 TRANSCRIBERS: AAmul, MD, AmaraMD, Alpha17

 MICROBIOLOGY
SPIROCHETES I (TREPONEMA)
Doc Bartolome | December 4, 2020

● (+) after 2-3 weeks of untreated syphilis  revert to

negative in 6-18 months and by 3 years after effective
treatment
● (+) in high titer in secondary syphilis
● If (+) late after treatment  ineffective Tx

TREPONEMAL TESTS
● Measure Ab’s vs. T. pallidum antigens
● Used to confirm if a (+) result from nontreponemal test is
truly (+) or falsely (+)
● Serial dilution of serum not done
● Report as reactive or non-reactive
● T. pallidum Particle Agglutination (TP-PA) – most widely
used in U.S.
● T. pallidum Hemagglutination (TPHA) & micro-
hemagglutination (MHA-TP) - based on the same
principles as the TP-PA but use sheep erythrocytes rather
than gelatin particles and may be more prone to
nonspecific agglutination.
● Fluorescent Treponemal Antibody Absorbed (FTA-ABS) –
most commonly used
● If (+) IgM FTA in blood of newborn  (+) in utero infection
● Not helpful in diagnosis of neurosyphilis but if (-), exclude
neurosyphilis

TREATMENT
DOC: Penicillin
● Long-acting benzathine PEN for early stages
● Penicillin G for congenital and late syphilis (only PEN for
neurosyphilis & pregnant patients)
● Alternatives: tetracycline & doxycycline
● No available vaccine

TREPONEMA PALLIDUM SUBSPECIES ENDEMICUM

(BEJEL)
● Endemic syphilis or bejel
● common in young children
● Distribution: Chiefly Africa; also Middle East, SE Asia, and
● Diagnosis of neurosyphilis and congenital syphilis based elsewhere; usually children
on clinical symptoms and laboratory findings ● MOT: person-to-person (contaminated eating utensils)
o VDRL test on CSF highly specific but not sensitive  (- ● Lesions:
) test does not rule out o Initial: Nondescript oral lesions
o (+) FTA-ABS CSF test consistent with neurosyphilis but o Secondary: oral papules & mucosal patches
not diagnostic o Late: gummas of skin, bones, and nasopharynx
● (+) serologic test results in infants may represent passive ● Treatment:
transfer of Ab’s from mothers o Benzathine penicillin
o Measure antibody titers in sera for 6 months  Ab titers o Children < 10 y/o: 600,000 U benzathine penicillin IM
in non-infected infants decrease to undetectable levels o > 10 y/o: 1.2 million U IM
within 3 months of birth; remain elevated in infants with o Single dose azithromycin 30 mg/kg not to exceed 2
congenital syphilis grams (WHO recommendation)

TREPONEMA PALLIDUM SUBSPECIES PERTENUE

(YAWS)
● Yaws: Frambesia (Granolamatous disease)

4 TRANSCRIBERS: AAmul, MD, AmaraMD, Alpha17

 MICROBIOLOGY
SPIROCHETES I (TREPONEMA)
Doc Bartolome | December 4, 2020

● Endemic among children (<15 y/o) in humid, hot tropical

countries
● MOT: direct contact with infected skin lesions containing
abundant spirochetes
● Primary lesion: ulcerating papule, usu. on arms or legs,skin
lesions
● Late destructive lesions of the skin, LN, and bones  scar
formation common
● Papillomatous lesions- painless nodules, widely distributed
over body with abundant contagious spirochetes
● (+) cross-immunity with syphilis
● Diagnosis & treatment same as syphilis
● Dramatic improvement with PEN
● Primitive tropical areas: South America, Central africa and
SouthEast Asia

TREPONEMA CARATEUM (PINTA)

● Endemic in all age groups in Mexico, Central & South
America, the Philippines, and some areas of the Pacific
● Primarily Restricted to dark-skinned races (Incubation 1-
3weeks)
● MOT: direct contact on skin lesions OR through flies or
gnats
● Primary lesion: non-ulcerating, small pruritic papule on
exposed areas
o Months later  flat, hyperpigmented lesions on skin 
depigmentation & hyperkeratosis years after
● Secondary lesion: enlarge plaques, persist for months to
years

REFERENCES
1. Lecture Notes
2. Recordings
3. Powerpoint
4. Medical Microbiology 28th Edition – Jawetz

**USE AT YOUR OWN RISK!!!**

5 TRANSCRIBERS: AAmul, MD, AmaraMD, Alpha17

MICROBIOLOGY

FAB, MD | 12/03/2021 MD 2024

GENERAL CHARACTERISTICS
SPIROCHETES I - TREPONEMA
• Gram negative, actively motile
• Slender; corkscrew-shaped; regularly spaced at
GENERAL CHARACTERISTICS OF SPIROCHETES a distance of 1 μm from one another
• Spirochete – Greek for “coiled hair” o Seen only with immunofluorescent
• Gram negative stain or darkfield microscope
• Divide by transverse fission • With pointed tapering ends
• Thin, helical, tightly coil (corkscrew) spirals with • Stain with difficulty except with Giemsa’s or
regular intervals and tapered or pointed ends silver stain
• Motile – rotational, forward movement STRUCTURE
• Outer sheath: glycosaminoglycan coating
TREPONEMAL SPECIES (mucoid layer) – enclose axial fibrils (responsible
1. Treponema pallidum for the movement located in the periplasmic
o T. pallidum subspecies pallidum (Syphilis) space)
o T. pallidum subspecies endemicum (Bejel) • Outer membrane/cell wall – inside the sheath;
o T. pallidum subspecies pertenue (Yaws) contains peptidoglycan; maintain structural
2. Treponema carateum (Pinta) integrity
• Endoflagella/axial filaments/periplasmic fibrils –
CLASSIFICATION OF HUMAN TREPONEMA within periplasmic space; encased by outer
membrane → rotation and flexion movements
• Inner or cytoplasmic membrane – within endo-
flagella; osmotic stability; cover protoplasmic
cylinder
• Cytoplasmic tubules (body fibrils) – near inner
membrane

❖ Can be classified into pathogenic and non-

pathogenic
❖ Non-pathogenic treponema can be found in
the normal commensals in the mouth
TREPONEMA PALLIDUM
❖ Tremos - turn
❖ Nema - thread PHYSIOLOGIC PROPERTIES
❖ Pallid – pale 1. Majority is Microaerophilic (1% - 4% oxygen),
❖ Difficult to visualize after gram staining some aerobic or anaerobic – extremely
sensitive to oxygen toxicity

PAGE 1 | 7 WEEB MD
MICROBIOLOGY

FAB, MD | 12/03/2021 MD 2024

2. Do not grow on cell-free media EPIDEMIOLOGY
a. Inoculate in: testes of rabbits OR • Syphillis is NOT highly contagious!
anterior eye chamber o 30% chance of acquiring after single
3. Slow growing exposure to infected partner
a. Has a doubling time of 30-33 days o Transmission rate dependent on stage
4. No TCA cycle – depend on host cells for purines, of disease (primary and secondary
pyrimidines and most amino acids stage only- treponema seen in the
5. In the presence of reducing substances → lesion)
remain motile for 3-6 days at 25C IMMUNITY
6. In whole blood or olasma stored at 4C → • INITIAL RESPONSE: production of
remain viable for at least 24 hours antiphospholipid antibodies
7. Some are free-living, part of normal flora of • Temporary depression of CMI
humans, or animals • IgG anti-treponemal antibodies – immobilize
8. Same serologic response in humans and kill organisms
9. Susceptible to penicillin ❖ Syphilis has a long duration per stage; rare to
CULTURE see IgM antibodies
Non-pathogenic or saprophytic strains (Reiter strain) • Factors contributing to persistent infection:
• Anaerobic culture in vitro → 30 hours 1. Delayed synthesis of protective IgG
doubling time antibodies → allow infection of tissues
• Defined medium containing amino acids, inaccesible to immune system
vitamins, minerals, salts, and serum albumin 2. CMI is not portective
3. Organisms covered by fibronectin →
OTHER CHARACTERISTICS enhance attachment to endothelium &
• Rapidly killed or immobilized by protective barrier against the immune
o Drying system
o High temperature (42C) PATHOGENESIS
o Trivalent arsenical, mercury & bismuth 1. Adherence to skin or mucosal membranes →
• Metabolic inactivity (NO TCA cycle) + slow produce hyaluronidase → promote tissue
multiplication rate of organism → slow rate of invasion
killing using penicillin 2. Organism becomes coated with host
fibronectin → protect against phagocytosis and
VIRULENCE FACTORS
immune recognition
• Soon after infection → hematogenous spread
VIRULENCE FACTOR FUNCTION → other skin sites & to other organs
• Skin lesions of primary syphillis → represent the
Outer membrane Lipids: keep the proteins primary site of initial replication
proteins covalently inaccessible to antibodies • Tissue destruction primarily due to host’s
bound to lipids Proteins: promote adherence immune response to infection
to host cell PATHOLOGY
• Main lesion: endarteritis (blood vessels and
perivascular areas)
• Lead to:
o Extensive tissue necrosis and scarring
Hyaluronidase Facilitate perivascular
• Spirochetes appear in lesions and blood during
infiltration; enhance
first 2 stages → highly communicable
invasiveness
INFECTIOUS DOSE
• Estimated average inoculum: 500-1000 in
Coating of Protect against phagocytosis humans
fibronectin • 60 treponemes – infect 50%
Species-specific Ag Evasion of immune system • Inoculation occurs at any body site
on cell surface o External genitalia – most common
o Mouth, anus, cervix, other sites
Hemolysin Hemolysis of RBC Phases of Disease
1. Primary phase
• Chancres at site of penetration → primary site
❖ Immunnopathology: tissue destruction and lesions of initial replication
primarily due to host’s immune response • Endarteritis and periarteritis; PMNs &
MODE OF TRANSMISSION macrophages
1. Sexual contact (90-96%) during primary stage • Lesion will resolve on its own even without
2. Skin contact with disseminated rash during treatment
secondary stage – may be accidental conatc 2. Secondary Phase
(ex. Medical personnel) • (+) clinical signs of disseminated disease
3. Congenital or placental • Skin lesions
4. Transfusion of contaminated blood

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• Already has evidence of bacteremia →
neurologic manifestations (early neurosyphilis)
❖ Latent syphilis can revert back to secondary or
go to tertiary syphillis
3. Late Phase (Tertiary)
• Systemic spread → virtually all tissues involved
• CNS and CVS involvement
• Has the late neurosyphilis manifestation
❖ All stages have skin lesions, but differ from each
other
o Primary: called hard chancre to
differentiate it from soft
chancre/chancroid caused by
hemophilus ducreyi ❖ Upper left: chancre on lips and palate
❖ Lower left: Multiple chancre
❖ Upper right: Solitary chancre
❖ Lower right: Labial chancre
Acquired Syphilis: Secondary Stage
• 3-8 weeks after disappearance of chancre
• Clinical evidence of disseminated disease
• “Flu-like” syndrome (myalgia, low grade fever) +
lymphadenopathy
• Some with alopecia areata
❖ Secondary stage - 2 lesions:
• Lesions - highly infectious
❖ In syphillis, everything is painless (painless ulcer 1. Generalized mucocutaneous rash
and lymphadenipathy) – distinguish it from o Red maculopapular rash anywhere in
other STI that have same lesion the body
o Ex. Chancroid has a painful ulcer and including
lymphadenopathy the hands
Acquired Syphilis: Primary Stage & feet
• Chancre: painless, ulcerated skin lesion at the
site of inoculation; 10-90 days after initial
infection
o 90% on genitalia; 5-10% extragenital
(lips)
• Painless Lymphadenopathy: 1 – 2 weeks after
appearance of chancre 2. Condylomata (wart-like) lata/latum
• Spontaneous healing of the chancre within 3 to o Moist, pale papules in anogenital
6 weeks → does not indicate a cure region,
• Primary histopathology: arteritis and periarteritis axillas,
• Highly infectious and
• Initial infection – 10-90 days → papule → mouth
painless ulcer with raised border (chancre) →
spontaneous healing within 2 months
o Abundant spirochetes present in the
chancre → disseminate via lymphatics
or blood stream
o Secondary lesions appear 2 – 10 • Other manifestations:
weeks after resolution of primary lesion o Syphilitic meningitis
• Abundant spirochetes present in the chancre o Chorioretinitis
→ disseminate via lymphatics or blood stream o Hepatitis
• Secondary lesions appear 2-10 weeks after o Nephritis (immune complex type) -
resolution of primary lesion Type III hypersensitivity
❖ Primary stage: only 1 lesion (chancre) o Periostitis
• Lesions also rich in spirochetes → highly
infectious
• Rash & symptoms gradually resolve
spontaneously within 6 to 8 months of infection
o 30% complete cure without Tx
o Others become dormant in liver and
spleen

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o 13%-15% of untreated cases progress
to latent syphilis (asymptomatic)
Acquired Syphilis: Latent Stage
• Eclipse/window period; usually 2 years
(depends on how much time has elapsed since
the chancre)
• Clinically inactive stage but with (+) serologic
tests
• 30% of untreated infection
• Early latent infection (infection <12 mos.) and
late latent (infection > 12 mos. ago)
Acquired Syphilis: Tertiary (Late) Stage
• 1/3 of untreated patients
• Activation of dormant treponemes 3 – 30 years
later in untreated cases
• Diffuse, chronic inflammation
Congenital Syphilis
• Degenerative, irreversible necrotic lesions; no
• Transmission: beginning in the 10th – 15th weeks
spirochetes on lesions
AOG
• Characteristics:
• Septicemia in developing fetus and widespread
1. Granulomatous lesions (gummas) in skin,
dissemination
bones, and
• Early congenital: rhinitis + desquamating
liver (hepar
maculopapular rash (same in secondary stage
lobatum)
in adults), mucocutaneous lesions,
hepatosplenomegaly, lymphadenopathy
• Late congenital: interstitial keratitis, Hutchinson’s
teeth, saddle nose, mulberry/Moon’s molars,
periostitis, CNS anomalies, saber shins (tibia),
symmetrical joint swelling (Clutton’s joints),
deafness
o Hutchinson’s Triad: 8th nerve deafness,
impaired vision, notched peg-shaped
2. Degenerative CNS changes (neurosyphilis)
teeth
– meningovascular, general paresis, tabes
dorsalis

❖ Argyll Robertson Pupil (Light-Near Dissociation)

o Bilateral small pupils
o (+) constriction on accommodation
o (-) constriction when exposed to bright
light
3. CV lesions – aortitis, aortic aneurysm, aortic
valve insufficiency/regurgitation
Late neurosyphilis
• Develops in 1/6 of cases, usually >5 years after
initial infection
• CNS and spinal cord involvement
o Cerebral atrophy most prominent in
frontal lobes (behavior changes and
memory loss)
• Dementia, seizures, wasting, etc.

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o Results positive in most patient with
primary syphilis → remain (+) for life
▪ Not used to determine
response to treatment

DIAGNOSIS • Nucleic Acid-Based Tests (PCR):

o For detecting T. pallidum in:
DIAGNOSTIC METHOD OF EXAMINATION 1. Genital lesions
TEST 2. Infant blood
Microscopy Darkfield 3. CSF
Direct fluorescent antibody staining • Serologic Tests (Antibody Tests): Nontreponemal
(DFTA) Tests
Culture Not available o Screening tests; not sensitive in early
Serology NONTREPONEMAL TESTS – detects syphilis
antibodies against non-specific o Antigens: measured amounts of
antigen cardiolipin (from beef heart),
• Venereal Disease Research cholesterol & purified lecithin
Laboratory (VDRL) – common o Antibodies: syphilitic IgG and IgM
• Rapid Plasma Reagin Test reaginic antibodies
(RPR)- common ▪ Antibodies vs. lipoprotein-like
• Unheated Serum Reagin (USR) material released from
Test damaged host cells and
• Toluidine Red Unheated Serum cardiolipin released from the
Test (TRUST) treponemes
TREPONEMAL TESTS – antibodies o VDRL & RPR – flocculation tests; detect
specific to treponemal antigens IgG and IgM early in infection
• Fluorescent Treponemal
Antibody Absorption (FTA-ABS)
• Treponema pallidum Particle
Agglutination (TP-PA)
• Enzyme Immunoassay

LABORATORY TESTS
• Specimen: tissue fluid from early surface lesions;
blood serum for serology
• Dark-Field Examination
o Typical motile spirochetes
o Exudates from skin lesion; primary,
secondary and congenital syphilis
• Immunofluorescence
o Fluorescent spirochetes; more useful

❖ VDRL vs RPR
➢ VDRL form small aggregates – need a
microscope
➢ Antigen used in VDRL and RPR are the
same
• Indirect fluorescent antibody technique

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o Measure antibody titers in sera for 6
o Only the VDRL test should be used to months → Ab titers in non-infected
test CSF from patients with infants decrease to undetectable
neurosyphilis levels within 3 months of birth; remain
o (+) after 2-3 weeks of untreated syphilis elevated in infants with congenital
→ revert to negative in 6-18 months syphilis
and by 3 years after effective
treatment
o (+) in high titer in secondary syphilis
o If (+) late after treatment → ineffective
Tx or reinfection
Serologic Tests: Treponemal Tests
o Measure Ab’s vs. T. pallidum antigens
o Used to confirm if a (+) result from
nontreponemal test is truly (+) or falsely
(+)
o Serial dilution of serum not done
o Report as reactive or non-reactive
❖ T. pallidum Particle Agglutination
(TP-PA) – most widely used in U.S.
❖ T. pallidum Hemagglutination
(TPHA) & micro-hemagglutination
(MHA-TP)
❖ Fluorescent Treponemal Antibody
Absorbed (FTA-ABS) – most
commonly used
❖ If (+) IgM FTA in blood of newborn
→ (+) in utero infection
❖ Not helpful in diagnosis of
neurosyphilis but if (-), exclude
neurosyphilis TREATMENT, PREVENTION, & CONTROL
• DOC: Penicillin
• If <1 year of disease: Benzathine penicillin IM
single dose
CONDITIONS WITH CONDITIONS WITH FALSE • If > 1 year disease: Benzathine penicillin IM once
FALSE (+) (+) TREPONEMAL TEST a week x 3 weeks
NONTREPONEMAL TEST • Late stages: admitted, Penicillin IV x 10 days
1. Viral infection 1. Pyoderma
2. Rheumatoid 2. Rheumatoid arthritis Primary & Secondary Syphilis
arthritis 3. SLE • Benzathine penicillin (long acting) 2.4 M units IM
3. SLE 4. Psoriasis once a week x 3 weeks; if < 1 year duration,
4. Acute or chronic 5. Crural ulceration single dose only
illness 6. Skin neoplasm • Follow up at 3,6 and 12 months with VDRL or
5. Pregnancy 7. Drug addiction RPR
6. Recent 8. Mycoses
immunization 9. Lyme disease Tertiary Syphilis
7. Drug addiction 10. Acne vulgaris • Aqueous penicillin G
8. Leprosy o High doses given since poorly
9. Malaria penetrates the brain
10. Multiple blood o Allergic reaction
transfusions Alternative drugs (if with allergy to penicillin)
• Doxycycline 100 mg BID x 15 days
• Azithromycin or Erythromycin
• Diagnosis of neurosyphilis and congenital Complication of Treatment: JARISCH-HERXHEIMER
syphilis based on clinical symptoms and REACTION
laboratory findings • Attributed to lysis of treponemes and release of
o VDRL test on CSF highly specific but endotoxin-like substances
not sensitive → (-) test does not rule • Flu-like symptoms few hours after drug
out administration
o (+) FTA-ABS CSF test consistent with • Also occurs after treatment of other spirochetal
neurosyphilis but not diagnostic diseases (Lyme disease, Leptospirosis, Relapsing
• (+) serologic test results in infants may represent Fever)
passive transfer of Ab’s from mothers

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TREPONEMA PALLIDUM SUBSPECIES ENDEMICUM
(BEJEL)
• Endemic syphilis or bejel
• Distribution: Chiefly Africa; also Middle East, SE
Asia, and elsewhere; usually children
MOT: person-to-person (contaminated eating
utensils)
• Lesions:
o Primary: nondescript oral lesions
o Secondary: oral papules & mucosal • Primary lesion: scaly, painless, pruritic papule on
patches exposed areas → erythematous rash
o Late: gummas of skin, bones, and • Secondary: enlarged plaques (persist months –
nasopharynx years)
• Late: disseminated, recurrent hypopigmentation
or depigmentation of skin lesion, scarring and
disfigurement

• Treatment:
o Benzathine penicillin
▪ Children < 10 y/o: 600,000 U
benzathine penicillin IM
▪ > 10 y/o: 1.2 million U IM
o Single dose azithromycin 30 mg/kg not
to exceed 2 grams (WHO
recommendation)
Organisms Transmission
TREPONEMA PALLIDUM SUBSPECIES PERTENUE T. pallidum Sexually transmitted
(YAWS/FRAMBESIA/GRANULOMATOUS DISEASE) disease
• Endemic among children (<15 y/o) in humid, Vertical transmission from
hot tropical countries (like Philippines) mother to infant
• MOT: direct contact with infected skin lesions Blood transfusion (human
• Primary lesion: ulcerating papule, usu. on arms only)
or legs
T. pertenue Direct skin contact
• Late destructive lesions of the skin, LN, and
(human only)
bones → scar formation common → common in
T. carateum Direct skin contact
the legs
(human only)
• (+) cross-immunity with syphilis
T. endemicum Direct mucosal contact
o Diagnosis & treatment same as syphilis
(human contact)
o Dramatic improvement with PEN
Contaminated eating or
drinking vessels

TREPONEMA CARATEUM (PINTA /CARATE/MAL

DE PINTO)
• Endemic in all age groups in Mexico, Central &
South America, the Philippines, and some areas
of the Pacific
o Restricted to dark-skinned races
• MOT: direct contact OR through flies or gnats
• Incubation: 1-3 weeks

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