Leptospira Interrogans

Question 1

Classification

Answer 1

Family: spirochaetaceae

Genus: Leptospira

Species: interrogans

Question 2

Morphology

Answer 2

Gram negative

Thin, tightly coiled and flexible

One end is often bent, forming a hook

Actively motile

Question 3

Growth characteristics

Answer 3

Grows best in 28 to 30oC in semisolid medium

Obligate aerobes

Letospirae derive energy from oxidation of long-chain fatty acids and cannot use amino acids or carbohydrates as major energy sources

Requires several B vitamins to survive

Ammonium salts are a main source of nitrogen

Leptospirae can survive for weeks in water, particularly alkaline pH

Question 4

Antigenic structure

Answer 4

Lipopolysaccharide

Perisplamic flagella

Question 5

Virulence factor

Answer 5

Highly motile

Endotoxin (LPS)

Pathogenicity not well understood

Question 6

Disease

Answer 6

Leptospirosis

Transmitted by: food or drink contaminated by urine of infected animals (rats, pigs, cows)

Febrile onset with symptoms due to dysfunction of the liver (jaundice, hemorrhage), kidneys (nephritis) and CNS (as aseptic meningitis)

Question 7

Microbiological diagnosis

Answer 7

DME:

Dark field microscopy:
Thin, tight spirals, with corkscrew-like motility and hooked ends

Giemsa stain

Culture:
Fletcher’s medium is used and culture should be kept for several weeks

Serologic tests:
Screening macroscopic agglutination test using killed leptospiras

Original microscopic agglutination test using live leptospiras

Question 8

Treatment and prevention

Answer 8

• tetracycline and penicillin are recommended

- no immunization