leptospira sp

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Leptospira sp.Defnition

Leptospira are spiral bacteria (spirochaete) in the amily o Leptospiraceae.

There are eight pathogenic, seven non-pathogenic Leptospira species, and

fve intermediate species with unnown ability or causing disease.

!orphology " #dentifcation

TYPICAL ORGANISM

• Tightly coiled, thin, $e%ible spirochetes &'& m long, with very fne

spirals *.'*.+ m wide one end is oten bent, orming a hoo

• nncased in a -& layer outer membrane or envelope. /eneath are

the $e%ible, helical peptidoglycan layer and the cytoplasmic

membrane these encompass the cytoplasmic contents o the cell.

The structures surrounded by the outer membrane are collectively

called the protoplasmic cylinder

• 0ctively motile, which is best seen using a dar-feld microscope

•

1as + Periplasmic fagella, one originating at each end o the cell. The ree ends o the $agella e%tend toward the center o the cell

• The basal bodies o Leptospira periplasmic $agella resemble those o

2ram 've bacteria

• lectron micrographs show a thin a%ial flament and a delicate

membrane

• The spirochete is so delicate that in the dar-feld view it may appear

only as a chain o minute cocci. #t does not stain readily but can be

impregnated with silver

CULTURE

• 2row best under aerobic conditions at +3'*45 in semisolid medium

(!61, others) in * mL test tubes with *.7 agar and &-$uorouracil• 0ter '+ wees, the leptospires produce a di8use 9one o growth

near the top o the tube and later a ring o growth at a level in the

tube corresponding to the level o the optimal o%ygen tension or the

organisms

GROWTH REQUIREMENTS

• Derive energy rom o%idation o long-chain atty acids and vitamins

/ and /+

• 5annot use amino acids or carbohydrates as ma:or energy source

• 0mmonium salts are a main source o nitrogen

• Leptospirae can survive or wees in water, particularly at alaline

p1

Ta%onomy

Leptospira interrogans and L. borgpetersenii are the two most common

species causing diseases in human and animals. The traditional

classifcation system is based on biochemical and serologic specifcity to

di8erentiate between the pathogenic species, Leptospira interrogans, and

the ree-living nonpathogenic species, Leptospira bifexa. The species are

urther broen down to more than +** serovars o L interrogans and more

than ;* serovars o L bifexa. The serovars are urther organi9ed into

serogroups o L interrogans and serogroups o L bifexa. 0 second

classifcation system is based on D<0-D<0 hybridi9ation studies, which have

demonstrated a high degree o heterogeneity within the two species o thetraditional classifcation.



0ntigenic structure

• The main strains (=serovars=) o L interrogans are all serologically

related and e%hibit cross-reactivity in serologic tests

• #ndicates considerable overlapping in antigenic structure, and

>uantitative tests and antibody absorption studies are necessary or

a specifc serologic diagnosis

• The outer envelope contains large amounts o lipopolysaccharide o

antigenic structure that is variable rom one strain to another

Leptospira serovar and serogroups can be seen in the ne%t page

Lie cycle " transmission

• The ma:or reservoirs and carriers? mammalian species, including

rodents, cattle, pigs, domestic and wild animals

• 1umans are mostly accidental and dead end hosts

• The inecting organism is sustained naturally by chronic inection o

the renal tubules o maintenance hosts ater primary inection

• @rganisms are usually transerred rom animal to animal by direct

contact. The maintenance hosts or carriers can e%crete Leptospira in

their urine or long periods o time or or their entire lives

• Leptospires survive wees or months in moist and warm soil,

stagnant water at neutral or slightly alaline p1.

• 1umans are inected via direct contact with inected animal urine,

animal abortion products or most commonly through indirect contact

with inected urine-contaminated water. @ral route has been

reported. /reast mil transmission may occur. Ae%ual and vertical

transmission in humans occurs rarely.• 1umans at ris or leptospirosis are those with occupational

e%posure. These include armers, fshermen, miners, animal

slaughterers, veterinarians, sewage and canal worers, sugar cane

worers, soldiers, etc.

• Apecial events and activities clearly related to the diseases are

recreational water sports, including triathlon, canoeing and white-

water rating, and natural disasters, such as hurricanes, $oods, etc.

• Laboratory-ac>uired inection may occur when dealing with high

concentrations o organisms in culture



Bathogenesis

• 1uman inection usually results rom leptospires, oten in bodies o

water, entering the body through breas in the sin (cuts and

abrasions) and mucus membranes (mouth, nose, con:unctivae)

• 0ter an incubation period o '+ wees, variable ebrile onset during

which spirochetes are present in the bloodstream. The host responds

by producing antibodies that, in combination with complement, are

leptospiricidal. The leptospires are rapidly eliminated rom all host

tissues e%cept the brain, eyes, liver and idneys. They producing

hemorrhage and necrosis o tissue and resulting in dysunction o

those organs (:aundice, hemorrhage, nitrogen retention)• The illness is oten biphasic. 0ter initial improvement, the second

phase develops when the #g! antibody titer rises. #t maniests itsel

oten as =aseptic meningitis= with intense headache, sti8 nec, and

pleocytosis o the 5AC

• <ephritis and hepatitis may also recur, and there may be sin,

muscle, and eye lesions. The degree and distribution o organ

involvement vary in the di8erent diseases produced by di8erent

leptospira)

• 1epatitis is re>uent in patients with leptospirosis. idney

involvement in many animal species is chronic and results in the

shedding o large numbers o leptospirae in the urine this is

probably the main source o environmental contamination resulting

in inection o humans. 1uman urine also may contain spirochetes in

the second and third wees o disease.

• 0gglutinating, complement-f%ing, and lytic antibodies develop

during the inection. Aerum rom convalescent patients protects

e%perimental animals against an otherwise atal inection. The

immunity resulting rom inection in humans and animals appears to

be serovar-specifc

Diagnosistic Laboratory Test

SPECIMENS

• 0septically collected blood in a heparin tube, 5AC, or tissues or

microscopic e%amination and culture

• Erine should be collected using great care to avoid contamination

• Aerum is collected or agglutination tests

MICROSCOPIC EXAMINATIONS

• Dar-feld e%amination or thic smears stained by the 2iemsa show

leptospirae in resh blood rom early inections

• Dar-feld e%amination o centriuged urine

• Cluorescein-con:ugated antibodies or other immunohistochemical

techni>ues

CULTURE

• Fhole resh blood or urine can be cultured in a semisolid medium.

/ecause o inhibitory substances in blood, only or + drops should

be placed in each o fve tubes containing & or * mL o medium

• Ep to *.& mL o 5AC can be used

• @ne drop o undiluted urine can be used ollowed by one drop each

o *-old serially diluted urineGor a total o our tubes

• Tissue appro%imately & mm in diameter should be crushed and used

as the inoculum. 2rowth is slow, and cultures should be ept or at

least 3 wees

Aerology

• 0gglutinating antibodies frst appear &'H days ater inection and

develop slowly reaching a pea at &'3 wees

• Iery high titers may be attained (J?*,***). The test is highly

sensitive, but it is diKcult to standardi9e the end point is &*7

agglutination, which is diKcult to determine

• 0gglutination o the live suspensions is most specifc or the serovar

o the inecting leptospires

#mmunity

Aerovar-specifc immunity ollows inection, but reinection with di8erent

serovars may occur.

eerences?

!ansonMs Tropical Disease +

rd

dition 6awet9, !elnic, " 0delbergMs !edical !icrobiology +&th dition

http?NNwww.ncbi.nlm.nih.govNboosN</3O&N

http://www.ncbi.nlm.nih.gov/books/NBK8451/



leptospira sp

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