Leptospira is the causative agent of leptospirosis .This video try to describe brief description of leptospira

1. CHINNU SUDHEESH
ASST.PROFESSOR(MICROBIOLOGY)
AL-AMEEN COLLEGE OF MEDICAL SCIENCES

2. INTRODUCTION
 Members of the genus leptospira are actively
motile
 Delicate
 Numerous closely wound spirals
 Characteristic hooked ends
 Cannot be seen under light microscpe due to its
thinness
 Leptos means ‘thin or fine’
 Do not stain readily
 Observed under dark ground microscopy

3. CLASSIFICATION
 Genus leptospira classified into 2 species
 (a) leptospira interrogans
 (b) leptospira biflexa
 (1) Leptospira interrogans
 includes pathogenic leptospires of man and
animals
 species L.interrogans is classified into 22
serogroups
 Each serogroups has one or more serovarsss

4. (b) Leptospira biflexa
 It contains saprophytic leptospires found in
surface waters
LEPTOSPIRA INTERROGANS
MORPHOLOGY

5.  Spiral bacteria
 Numerous closely set coils and hooked ends
 Actively motile
 stain poorly with aniline dyes
 Can be observed by fluorescent antibody and
silver impregnation techniques
 Because of narrow diameter, they are best
observed by dark ground, phase contrast or
electron microscopy
 leptospires rotate rapidly about their long axis
and bending or flexing sharply

7. CULTURAL CHARACTERISTICS
 Aerobic and microaerophilic
 Optimum temp:28-32 degree celcius
 Can be grown in media enriched with rabbit
serum
 Media such as Korthof’s,stuart’s,and fletcher ‘s
medium have been described
 Semisynthetic medium ,such as, EMJH
(Ellinghausen ,McCullough ,Johnson ,Harris )
now commonly used

8.  In semisolid media, growth occurs a few
millimeters below the surface
 Growth is detected after 6-14 days of incubation
 Generation time in laboratory media – 12-16 hrs
 4-8 hours in inoculated animals
 Grown on chorio allantoic membrane of chick
embryo(CAM)
 Also grown in guinea pigs

9. PATHOGENESIS

10.  Leptospira interrogans causes ‘Leptospirosis’
 It is a zoonotic disease
 Also known as canicola fever, mud fever, swamp
fever, caver’s flu
 Leptospira present in water bodies
 Enter through break in the skin(cut and
abrasions)
 Enters through mouth-nose-conjunctiva
 Rarely enters through ingestion

11.  After an incubation period of 6-8 days , there is onset
of febrile illness with presence of leptospires in blood(
septicaemic phase)
 Which lasts for 3-7 days
 Then organisms disappear from the blood but enter
into the liver, kidney , spleen, and meninges then
produce ‘meningeal irritation’(head ache ,vomiting)
 They persist in the internal organs
 Most abundantly in kidney and therefore may be
demonstrated in urine in the later stages of the
disease
 Severe leptospirosis (Weil’s disease) associated with
fever, conjunctivitis , albuminuria , jaundice &
haemorrhage

12.  It is a fatal disease with hepatorenal damage
 Three important serogroups of L.interrogans –
leptospira canicola, leptospira hebdomadis
,&leptospira icterohaemorrhagiae are responsible
for most of human cases of leptospirosis

13. LABORATORY DIAGNOSIS
 Laboratory diagnosis depends on microscpical
demonstration of leptospires
SPECIMEN
 Blood
 Urine
 Csf
(a) Demonstration of leptospires in blood/urine
 By dark ground microscopy
 Blood examination is useful in first week
 As leptospires disappear from blood after 8 days
 Leptospires present in urine in the second week

14.  centrifuged deposit of urine may be
examined by dark ground microscopy

15. CULTURE
 Specimen of blood
During first week and
Urine in second week
( upto 6 weeks) can be
Cultured in modified
Korthof’s medium, or
Fletcher ‘s semi-solid
Medium
 Centrifuged deposit
Of urine is cultured
 Media then incubated at 28-32 degree celcius aerobically
 Examined by dark ground microscopy every third upto 6
weeks before regarding as negative

16. ANIMAL INOCULATION
 Blood or urine
↓intraperitoneally
Guinea pig(young)
↓
3rd day after inoculation
↓
peritoneal fluid collected
↓
daily examined under
dark ground illumination
↓
Heart blood of animal is
inoculated into culture media

17. SEROLOGICALTESTS
 Very useful method
 At the end of 1st week
antibodies begin to appear
 Continue to rise till the
Fourth week and then begin
to decline
 2 types of serological tests are
In uses

18. (a) Screening tests
 These are genus- specific
 using a broadly reactive genus specific antigen
 Usually non-Pathogenic L. biflexa Patoc -1 strain
 Tests include CFT , Haemagglutination test ,ELIZA
,Sensitized erythrocyte lysis (SEL) ,Agglutination
tests and indirect immunofluorescence
 These tests are capable of detecting IgM and IgG
antibodies
 Rapid dip –stick assay – detection of leptospira
specific IgM antibodys

19. (b) Serotype specific tests
 Microscopic and macroscopic agglutination tests
 Commercially available formalin –killed suspensions
of a number of reference strains are tested with
serial dilutions of test serum
↓
‘ MACROSCOPIC AGGLUTINATION TEST’
 Microscopic agglutination test – uses formalised or
living suspensions of well grown cultures
 Then observed under dark field microscopy

20. TREATMENT
 Penicillin
 Tetracycline
 Erythromycin

21. PROPHYLAXIS