9. Gram Negative Spirochetes.pptx

7/25/2019 9. Gram Negative Spirochetes.pptx

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Spirochetes

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Spirochetes

The name spirochete is derived from theGreek words for "coiled hair.

Large heterogonous group, motile organisms

Most are free living and non pathogenic but

some pathogenic Have unique helical structure

ell wall similar to gram negative bacteria

Have a!ial agellafor motilit#

$re refractive

%orrelia, Leptospira and Treponema areamong the important once


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Genus Treponema

Gram&negative, thin,motile, spiral shaped

pathogenic and '( t#pes

non stained

non cultivablein vitro

Human pathogens cause

treponematoses ) are T. pallidum-

venereal syphilis


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Syphilis

Syphilis, a chronic s#stemic infection

caused b# Treponema pallidum

subspeciespallidum

usuall# se!uall# transmitted

pass through the placenta to infect the

fetus*congenital Syphilis)+ $ppro!imatel# - percent of fetuses are

aborted or stillborn. the rest e!hibit

diverse s hilitic sti mata


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Clinical Manifestations rimary syphilis

multiplication of treponemes at the site of entr#

produces erythematous and induration+

a hard chancre formation * painless / +

H. ducreyicauses soft chancre*painful+/

'umerous treponemes are present highl#

contagious, open lesion+ $fter 0 to weeks of s#mptoms, this primar# lesion

heals, leaving onl# remnants of scar tissue+


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2econdar# s#philis

$fter an as#mptomatic 0 to 03 weeks,

4rganisms multipl# in many di!erent

tissues+ +

$ll of these lesions be loaded with

treponemes and are highl# contagious+

"oth primary and secondary syphilisare contagious


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Tertiar# s#philis 2mall proportion of cases progress to

tertiar# stage of s#philis after a latentperiod+

can a5ect almost an# tissue+

'earl# 6- percent of fatalities are

caused b# cardio vascular

involvement

0- percent are from neurologic

involvement


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#enereal syphilis

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(rimar# s#philis with

a 8rm, nontenderchancre

2econdar#

s#philisdemonstratingthepapulosquamoustruncal eruption+

2econdar#s#philiscommonl#a5ects the

palms andsoleswithscaling, 8rm, red&brown papules+


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#enereal syphilis

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Mucous patches on

the tongue of apatient withsecondar# s#philis+

ond#lomata lata aremoist, somewhatverrucous intertriginousplaques seen insecondar# s#philis+


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La$oratory diagnosis

T. pallidumcannot be grown in vitro,

laborator# diagnosis hinges on

microscop# and serolog#+


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Serologic

are mostly used that include: Non specific ( nonTreponemal ) tests

measure antibodies directed against lipid

antigens (cardiolipin)---derived from hosttissues

Ex. VDRLand RPRtests

More sensitive, rapid, simple but non specific,malaria, leprosy, auto immune ds, measles

infection may give false positive results


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Treponemal tests

which detect antibodies directed against

protein constituents of T.pallidum

+e!ample

9luorescent T pallidum$ntibod#&

$bsorption *9T$&$%2/

Micro hemagglutinationT.pallidum

*MH$&Tp/

T+( immobili:ation test


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#enereal syphilisTreatment

(enicillin

tetrac#cline or do!#c#cline if allergic for penicillin

(atients with other 2T;s should be screened for

s#philis Congenital syphilis is completel# preventa$le if

women are

Screened serologically earl# in pregnancy *% &

months/

Those who are positiveare treated withpenicillin+

Methods to $loc' direct mucosal contact *condoms/13


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Genus (ic'ettsiaGeneral characterstics

2mall, structurall# similar to Gram&

negative bacilli

o$ligate intracellular parasites of

eu'aryotic cells

found in ticks, lice, eas, mites,chiggers, and mammals

Grow readil# in yol' sacs of

em$ryonated eggs or cell culture1


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1


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Rickettsiae

Most


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pidemic Typhus louse-$orne)

;ue to infection with R. prowazekii Transmitted b# the human $ody louse *Pediculus

humanus corporis/ Lives on clothes found in poor h#gienic conditions usuall# in cold areas

Lice acquire R. prowazekiiwhen the# ingest a bloodmeal from a rickettsemic patient

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multipl# in the mid gutepithelial cells of thelouse

spill over into thelouse feces

patient auto inoculates theorganisms b# scratching

louse defecates

during its bloodmeal

The louse does not pass R. prowazekii


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iagnosis

cult to diagnose bothclinicall# and in the laborator#

ultivation requires viable eukar#otic hostcells, such as antibiotic&free cell cultures,embr#onated eggs, and susceptible

animals+

Rickettsia


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Treatment and revention

broad&spectrum antibiotics, doycycline,tetracycline, and chloramphenicol

(revention of e!posure to infected

arthropods o5ers some protection+

revention is $ased on reducing

eposure to the vector e.g. louses)

0-


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Genus Chlamydiae

hlam#diae are o$ligate intracellular

$acteria

lack several metabolic and bios#ntheticpathwa#s * depend on the host cell for

intermediates, including $T(/

Lack (eptidogl#can la#er

hlam#diae consist of three species,

C.trachomatis, C.psittaci, and01


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Medically important chlamydiaceae

00


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Chlamydia trachomatis + trachomatis is found onl# in humans+

causes the following diseases)

Trachoma, a chronic follicular keratocon?unctivitis+

@nclusion con?unctivitis in ne*$ornchildren

'onspeci8c urogenital infections in both men and

women *urethritis, cervicitis, salpingitis)

L#mphogranuloma venereum, a venerealdisease observed mainl# in countries with warm

climates+


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+ pneumoniae

responsible for infections of the upperrespirator# tract

mild form of pneumonia


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Trachoma

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9igure hlam#dial con?unctivitis is thecommonest form of neonatal con?unctivitis


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Trachoma

pidemiology

A 3-- million people throughout the worldhave trachoma * 0- million are blinded b#it /

Most prevalent in $frica

$sia

The Mediterranean basin

childhood infection ma# be universal,and severe blinding disease is common

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hygienicconditions arepoor and*ater is

scarce


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0=

9igure 3 L#mphogranuloma venereum+ %ilateralenlargement of inguinal glands

Genital /nfections


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Tetrac#cline, er#throm#cin, rifampin,

sulfonamides, chloramphenicol

$:ithrom#cin is e5ective and can be

given to pregnant women

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Treatment of chlamydial infections


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Bnd for

2#s+%acteriolog#

07


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C-


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C1

#/(0L/12CT/31S


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C0

0. e4nition

#iruses &are acellular, small obligate intracellular parasites

contain either


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CC

". Classi4cation

The following morphological and biochemical criteria are used forta!onomic classi8cation

Genome) ;'$ or


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C3

Diruses di5er widel# from other microorganismsin a number of characteristics)

have no cellular structure, consisting onl# ofproteins and nucleic acid *;'$ or


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C

i!erent virus species are sho*n here inside an E.

coli$acterium

General characteristics of #iruses


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C

General structure of #iruses


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C=


2ig #irus article Structure


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C6

Capsid

$ protein shell surrounding the genome

2erves to protect the viral genome*'ucleocapsid/ and introduce the viral genomeinto host cells

The shape of the capsid ma# be

@cosahedral s#mmetr#

Helical s#mmetr#

omple! s#mmetr#


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C7


/cosahedral 6elicalComple

*spherical/consists ofsubunitscalledcapsomer

s

*rod shapedor coiled/consists ofrepeatedunits called

protomers

@rregularshape*neitherhelical norpol#hedral/


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9unctions of capsid$+ (rotect the viral nucleic acid+

%+ (articipate in the viral infection+

+ 2hare the antigenicit#

3-


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nvelope

$ lipid&containing membrane that surrounds some viral

particles+

@t is acquired during viral maturation b# a budding process

through a cellular membrane,

Diruses&encoded gl#coproteins are e!posed on the surface of

the envelope+

1ot all viruses have the envelope, and viruses can be

divided into 0 kinds) enveloped virus andnaked virus+


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nvelope

( li ti f #i


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3C

7. 0dsorption) attachment of the virus to the

host cell surface

8. enetration) entr# of the virus into the host

cell

nveloped viruses) b# fusing with

plasma membrane or endoc#tosis

'on&enveloped) direct penetration

&. 9ncoating) ph#sical separation of viral '$

from the outer structural components

(eplication of #iruses

2teps in viral replication


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3

(eplication of #iruses5.

6o* #iruses cause diseases


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3=

There are several possible consequences ofinfection b# a virus

Lytic infections ersistent infections

Latent infections

Transformation

Lytic infections>result in the destruction of thehost cell

& caused b# virulent viruses, which inherentl#bring about the death of the cells that the# infect

ersistent infections)

infections occurring over relativel# long

periods of time

6o* #iruses cause diseases


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Latent infections> there is a dela# between the infection b#

the virus and the appearance ofs#mptoms

appear sporadicallyas the virusemerges from latenc#, usuall# triggeredb# some sort of stress in the host

Transformation> 2ome animal viruses have the potential

to change a cell from a normal cell into a

tumor cell *oncogenic viruses/

The vast ma?orit# of viral infections inhumans are inapparent or as#mptomatic

;iagnostic Methods in


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;iagnostic Methods inDirolog#

1+ ;irect B!amination

0+ 2erolog#

0+ @ndirect B!amination


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9. Gram Negative Spirochetes.pptx

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