lecture 28 leptospira

بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

LEPTOSPIRAProf. Khalifa Sifaw Ghenghesh

Actively motile spiral bacteria, appear straight and rigid with one or both ends hooked

Obligate aerobes, Optimum temp. > 28-32oC Many types are harmless, others cause

disease in warm-blooded animals (including domestic) and man (leptospirosis)

Pathogenic leptospires found in kidneys of rodents and other small mammals– Excreted in their urine

2 species– L. interrogans >> Parasitic strains– L. biflexa >> Free-saprophytic strains

Leptospira species

Leptospira species

Leptospira interrogans Require addition of serum for growth Slow growth requires 2-3 weeks

incubation in liquid media Can cause

– Benign leptospirosis with mild influenza-like illness (Canicola fever)

– Severe form of illness characterized by jaundice and haemorrhages in the eyes, skin and mucous membranes (Weil’s disease) Sometimes fatal Usually due to serovar icterohaemorrhagiae

LABORATORY DIAGNOSIS

Specimen– Blood > after 5-12 days incubation >

leptospiraemia for 7 days– Urine deposit > leptospires after 2nd week of

illness for 4-6 weeks (intermittently) Microscopy

– Dark-ground microscopy Culture:

– Blood > Liquid medium– Urine sediment > Semisolid medium

Serological Examination– Specific Abs in patients serum > end of 1st

week– Continue to rise for several weeks and then

decline– Serum examined early day of illness and at

intervals of 4-5 days thereafter– Rise in Ab titre is indication of current

infection– Tests used

Complement fixation and Haemagglutination tests, ELISA and Microscopic agglutination test

Leptospira bacteria in liver impression smear (FA stain) of a Patient died of

leptospirosis.

Histopathology of leptospirosis, kidney (Dieterle silver stain)

Photomicrograph of leptospiral microscopic agglutination test with live antigen using

darkfield microscopy technique.

TREATMENT AND CONTROL

Benzylpenicillin (IV) in large doses (3.6-4.8g) > daily for 7 days

Alternatives:– Erythromycin, Streptomycin

Control: