4.3 Spirochaetes

Background..

Gram negative Motile organismTightly coiled bacteria typically slender and

flexouas shape.The cell made up of protoplasmic cylinder

located in periplasm of cell, endoflagella and outer sheath.

Move by bending and rotating body according to the viscosity of the medium

Motility of spirochetes

Unusual mode of motility Endoflagellum located at one end and

extends about two-third of the cell. Its rotate.

Protoplasmic cylinder is rigid, whereas the outer sheath is flexible, therefore when both endoflagella rotates in the same direction while protoplasmic cylinder in opposite direction causing torsion of cell.

Medical important

3 genera:

1.Treponema2.Leptospira 3.Borrelia

Treponema

•Treponema pallidum pallidum, which causes syphilis •T. pallidum endemicum, which causes bejel or endemic syphilis •T. pallidum carateum, which causes pinta •T. pallidum pertenue, which causes yaws

YAWS PINTA

SYPHILIS

Normal habitat

Host associated spirochetes are parasites of humans or animals.

Found in lesion of treponematosesCan also found in mucous membranes in the

mouth and genital tract, also in skin ulcers

Pathogenicity (T.pallidum)

1. Acquired syphilis transmitted congenitally or sexual intercourse - Known as sexually acquired syphilis and congenitally acquired syphilis

2. Non-venereal syphilis – endemic syphilis, bejel, njovera, siti and dichuchwa

Microscopy

Small 6-15µm size, 0.2µm diameter.Motile spirochaetes.Use metallic silver techniques or known as

impregnation techniques. Metallic silver precipitates on the wall of the spirochete, enlarging its outline and making it opaque, features that make it visible in tissue sections.

Best seen by dark-field illumination or phase contrast

Culture

Microaerophilic Hardly to grow in routine cultureAble to survive in some fluid including citrated

whole bloodMaintained by intratesticular inoculation in

rabbit.

Serology tests

Cardiolipin antigens testVDRL test – Venereal Diseases Reference

LaboratoryRPR test – Rapid Plasma ReaginTreponemal antigen test TPHA test (Treponema pallidum

haemagglutination test)

Leptospira

Leptospira interrogans

Scanning electron micrograph of a number of Leptospira sp. bacteria atop a 0.1 µm polycarbonate filter

Normal Habitat

Gram negative, obligate aerobe spirochete.

Variety in domestic and wild animals such as rats, rodents, cattle, pigs and dogs. Humans are accidental host.

Largely secreted in urineSurvive many weeks in soil and water, in

alkaline and 28 – 32oC

Transmission

Direct or indirect contact with urine of infected animal

Enter damaged skin which has immersed for a long time in water or mud contaminated with infected urine

m/o penetrate the lining of the mouth, nose and eyes

Person to person transmission rarely occurs

Risk factors

Person most at risk of infection include workers in rice fields and sugar-cane fields, livestock farmers, irrigation canal workers, meat and animal handlers, fresh water fish pond workers, veterinarians, pest control officers, forest workers and those involved in road building

High cases in rainy seasons and times of flooding

Pathogenicity

Mild form usually misdiagnosed as viral illness and influenza

More serious infection causing a high continuous fever, severe headaches and body pain especially in the muscles of legs, redness of the eye and weakness.

Can also causing jaundice and renal failure

Microscopy

Small 6-20µm in size 0.1 µm diameterActively motile spirochetes Screw-tight coils and hooked endsEasily stain only by impregnation techniquesBest seen by dark-field illumination or phase

contrast

Culture

Leptospires are strictly aerobesCan be cultured in a serum or albumin-Tween

mediumLate grow so resulting less efficient diagnosticPreferable serology test to identify several

serogroups

Other tests

Haematological and biochemical tests in leptospirosis

Antimicrobial sensitivity – high doses of penicilin will be effective against L. interrogans

ELISA test, Polymerase Chain Reaction (PCR)

Borrelia

Borrelia burgdoferiBorrelia recurrentis

Borrelia duttoni

Normal habitat

B.burgdorferi – deer tick,Ixodes scapularis.B.recurrentis – parasite of Pediculus liceB.duttoni – parasite of Ornithodorus soft ticks

Pathogenicity

B.burgdorferi– causing Lyme Disease.B.recurrentis – louse-bourne relapsing fever in

poverty, overcrowding, and during time of drought and famine.

B.duttoni – tick-bourne relapsing fever infecting CSF causing lyphocytic meningitis

Microscopy

Large 10-20µm in size,0.5µm diameterActively motile spirochaetes wt coils of varying

sizeAgglutinate togetherEasily stain in Giemsa, Field’s or other

Romanowsky stain; prolonged Gram staining (Gram negative)

Well seen by dark-field illumination

Culture

Borreliae are aerobesCan be cultured in Kelly’s medium

Serology test

Used to diagnose relapsing fever, usually cross reaction with Treponema

Antimicrobial sensitivitySensitive to penicillin and tetracycline

THE END