بسم الله الرحمن الرحيم LEPTOSPIRA Prof. Khalifa Sifaw Ghenghesh
Actively motile spiral bacteria, appear straight and rigid with one or both ends hooked Obligate aerobes, Optimum temp. > o C 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 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 2 nd 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 1 st 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 ( g) > daily for 7 days Alternatives: – –Erythromycin, Streptomycin Control: