SPIROCHETES: Reading Assignment

Spirochetes

MORPHOLOGY

• Long, slender, helically curved, gram (-) bacilli

Spirochetes

Morphologic features

• axial fibrils

• outer sheath

• insertion disks

Spirochetes

With at least 8 genera

• Brachyspira (Serpulina) pilosicoli

• Brachsypira aalborgi

Spirochetes

Differentiation of genera is based on:

• number of axial fibrils

• number of insertion disk present

• biochemical or metabolic features

Treponema

Number of Axial Fibrils 6-10

Number of Insertion Disks 1

Cell Wall Content Ornithine

Oxygen Requirement Anaerobic

Treponema

Catalase Test -

Seen on light microscopy +

Overlapping axial fibrils +

Cytoplasmic tubules +

Borrelia

Number of Axial Fibrils 30-40

Number of Insertion Disks 2

Cell Wall Content Ornithine

Oxygen Requirement Microaerophilic

Borrelia

Catalase Test -

Seen on light microscopy +

Overlapping axial fibrils +

Cytoplasmic tubules -

Leptospira

Number of Axial Fibrils 2

Number of Insertion Disks 3-5

Cell Wall Content Diaminopimelic

Oxygen Requirement Aerobic

Leptospira

Catalase Test +

Seen on light microscopy -

Overlapping axial fibrils -

Cytoplasmic tubules -

Treponema

slender with tight coils

Borrelia

thicker with fewer and looser coils

Leptospira

resembles Borrelia but with hooked ends

Treponema

GENERAL CHARACTERISTICS

• fine spiral organisms

• spirals are regular and angular (4 - 14)

T. pallidum subsp. pallidum

Disease

Syphilis

Differentiating characteristics Cutaneous lesions in

Rabbit +

Hamster -

Guinea pig -

T. pallidum subsp. endemicum

Disease

Endemic Syphilis

Differentiating characteristics Cutaneous lesions in

Rabbit +

Hamster -

Guinea pig -

T, pallidum subsp. pertenue

Disease

Yaws

Differentiating characteristics Cutaneous lesions in

Rabbit +

Hamster +

Guinea pig -

T. carateum

Disease

Pinta

Differentiating characteristics Cutaneous lesions in

Rabbit -

Hamster -

Guinea pig -

Treponema

They cannot be grown it vitro

→ animal inoculation

→ rabbit testes

Treponema

Observed with the use of:

→ Dark-field microscopy

→ Phase-contrast microscopy

→ animal inoculation

→ rabbit testes

Treponema

Microaerophilic

Treponema

EPIDEMIOLOGY

• enter the host in two (2) types

→ penetrating the intact mucus membranes

→ entering through breaks in the skin

• causes endarteritis and tissue destruction

Syphilis

• A sexually transmitted disease

• Characterized by three (3) stages

Primary

characterized by chancre formation

Secondary

presents fever, lymphadenopathy, weight loss, & rash

Tertiary

gumma formation is its hallmark - involves CNS and CVS

Congenital Syphilis

• Organism is transmitted from the mother to the fetus

• All pregnant women are required to undergo a serologic

examination early in the pregnancy

• Can cause:

→ intrauterine death

→ congenital abnormalities

Syphilis

DIRECT DETECTION

• Darkfield Mx Examination

→ sample is collected from suspicious lesion

→ exudate is aspirated and placed in a slide & examined

→ organism appear white against a dark background

Syphilis

SEROLOGIC METHODS

• Nontreponemal tests

→ VDRL

→ RPR

• Treponemal tests

→ FTA-ABS

px serum is 1st absorbed with non- pathogenic treponemes

application of fluorescein-labeled anti-human globulin

serum

→ MHA-TP

utilizes RBC from a turkey coated w/ treponemal antigen

Borrelia

GENERAL CHARACTERISTICS

• gram (-), highly flexible organisms

• has 3 -10 spirals

• stains well with Giemsa & can be examined under light

microscope

• microaerophilic and requires long-chain fatty acids for growth

Borrelia recurrentis

• Causes human relapsing fever

→ fever, headache and myalgia

• Transmitted by louse or tick bite

Borrelia recurrentis

DIRECT DETECTION METHOD

→ Peripheral blood

→ Wet preparation of PB under dark-field illumination

→ Staining thick & thin blood smears

Borrelia recurrentis

CULTURE

→ Kelly medium

→ animal inoculation

suckling Swiss mice or suckling rats

Borrelia recurrentis

SEROLOGIC METHODS

→ difficult

Borrelia burgdorferi

• Causative agent of Lyme's disease

→ characterized by three (3) stages

erythema migrans (EM)

arthritis

chronic arthritis

• Transmitted by a tick bite

Borrelia burgdorferi

DIRECT DETECTION METHOD

→ tissue sections stained w/ Warthin-Starry silver stain or

Dieterle silver stain

→ blood, skin lesion and CSF stained w/ acridine orange,

fluorescent stain or Giemsa

Borrelia burgdorferi

CULTURE

→ Modified Kelly's medium

Borrelia burgdorferi

SEROLOGIC METHODS

→ Indirect immunofluorescent assay

→ ELISA

Leptospira

• Obligate aerobe spirochete

• Tightly coiled, thin flexible organism and can be grown in

artificial media

• Has more than 180 serotypes

Leptospira interrogans

• Causes leptospirosis

→ zoonotic disease

→ dogs, rats and other rodents are principal reservoir

• disease characterized by:

→ fever, chills and myalgia with renal, hepatic & CNS

involvement

• conjunctival suffusion is the characteristic finding

Leptospira interrogans

CULTURE

→ acute stage

blood or CSF

→ urine

after 1 week

→ Culture media:

Fletcher's and Stewart's media

EMJH (Ellinghausen's McCollough-Johnson Harris

medium)

Tween 80 albumin media

Leptospira interrogans

DIRECT EXAMINATION

→ darkfield microscopy, fluorescent ab & silver impregnation

Leptospira interrogans

SEROLOGY

→ Macro & Microscopic slide agglutination test

Borrelia

Morphology

Coarse, irregular coils

Motility

Move in forward and backward waves with a corkscrew-like motion

Axial fibrils

15-20; may/may not overlap

Insertion discs

2

Treponema

Morphology

Tight, regular coils

Motility

Sluggish with drifting motion and flexous movements

Axial fibrils

1-8; may/may not overlap at the center of the cell

Insertion discs

1

Leptospira

Morphology

Tight, regular coils with hooked ends

Motility

Undulatory movement and by rapid spinning on long axis

Axial fibrils

1; does not overlap at the center of the cell

Insertion discs

3-5