Spriochaetes, acid fast bascilli, parasitic bacteria quiz 5

General features of spirochetes

Long sledner helically curved gram neg

Unusual features spirochetes

Axial filaments or fibrilis - flagella liek organelles tahat wrap around cell wall

outer sheath - encloses the protoplasmic cylinder

insertion disks - plate like strucutres that anchor the spirochete to its environment.

Treponema pallidum subsp. pallidum disease

syphillis

treponema palladium susp. pertenue disease

Yaws

treponema palladium susp. endemicum disease

Endemic syphillis

treponema non pathogenic species disease

possible associated with Vincent’s disease - acute necrotizing ulcerative ginigivitis —> destructive lesion of gums

Treponema morphology

3 periplasmic flagella at each end

long thin spiral rods

best observed in phase contrast or dark field

Trepenoma cultivation

infect only humans

have been cultivated in vitro ( unlike other abcteria, difficult to culture in vitro (outside the body)

Trepenoma epidemiology and pathogenesis

Enter host by penetrating intact mucous membranes or skin breaks

spread via bloodstream

Mechanism is unclear : t.palladium has an affinity for arterioles —> tissue destruction

transmission of each trepenoma

T. palladium disease and transmission

Veneral syphillis

transmitted : sexual , direct contact with lesion, transplacental

3 stages of disease

3 stages of syphillis

Primary, Secondary, Tertiary

Primary syphillis sympotms

Formation of chancre (ulcer) - painless lesion, raised border and forms 21 days after infection

Chancroid- painFUL lesion (haemophilis ducreyi)

Painless ulcer can appear at gentials

Teeming with tropenemes

Secondary syphilius symptoms

2-12 weeks after chancre : sore throat, fever, gernalized lymphadenopathy, rash, and mucous membrane lesions

characteristic skin rash - lesion forms on mucous membranes, all highly infectious

Condylomata lata - may appear on moist body region, mucioid wart like growths

Latent syphillis

Disease becoems subclinical

diease is NOT inactive → detected by serological test

1/3 patietns exhibit biologic cure

1/3 pateients develop tertieary syphillis

1/3 patients remain latent for life with reactive serology

Tertiary syphillis

May appear 10-25 years after initial infection

formation gummas-granulomatous lesions

Neurosyphillis - degenerative changes in Centra nervous system

Syphilitic cardiovascular lesions - abnormalites of aurta and aortic valves

Ocular syphillis- intestinal keratitisand vision loss.

Congentital syphilis early

Trepenmes cross placenta - infected mother transmits the infection to the fetus, leading to a variety of health issues such as developmental delays, bone deformities, and potentially stillbirth.

Early : symptoms devleop 2-10 weeks post delivery

UNTREATED children develop late congential syphilis

Congentital syphilis late

Asymtomatic at birth

symptoms can appear during puberty

Intestional keratitis

hutchisons teeth or mulberry molars

eighth nerve deafness

= hutchinson’s traid = diagnostic criteria

Labraotory diagnosis syphillis

Direct detection : dark field microscorpy (most common) or fluroscent antobody exam of skin lesions (allows visualization of spirochetes, highly specific)

PCR can be used of rcongential syphillis, not widely avail tho

Serodiagnosis

Measure presence of treponal and on treponemal antibodies

treponemal AB - antibody against antigens of organsisms, specific to tset to sphyillis

Non treponal Ab - no specific reagin tests : Venereal Disease resarch lab (VDRL) and Rapid Plasma Reagin (RPR), used as a screen test, shows antibodies exist but not what kind

measures reagain (Ab to cardiopin, produced against components of mammallian cells)

Challenges in serodiagnosis

Cross reactivity

False pos results in conditions / other diseases

VDRL principle

Patient’s seruum is heat activated and mixed with biffered salin suspestion of VDRL antigen

Presence of reagin results in micro cluimping = flocculation

VDRL specimen

Blood serum or CSF

VDRL specficity / secondary test

Venereal disease reseach laboratory

good screening test : detects 78% primary syph, 99% secondary syph, 96% latent syph, 71% tertiary cases

Negative resullts with POSTIVE sympotms muist have a SECONDARY CONFIMATION test, with Treponema sensitive test

RPR test

More specific than VDRL and easier to perform

A Nontreponemal test, measuring antbodies that are not specific to bacteria, used to screen

Fluorescent trep AB absorbtion test

Serologic test for specific treponemal antobody

Confirmatory test for a pos scrern test (VDRL or RPR)

one pos = pos for life

confimatory test , detescts specific treponema ab

FTA-ABS specific step

Serum is first exposed to non T.pallidum treponemal antigens to remove nonspecific Abs from serum

T.pallidum particle aggultination

Uses gelatin particles sensitized with T.pallidum antigens

If specific antibody is present, gelatin particles will aggultinate and form a flat mat across the bottom of the test well

Quantitiative serum titers of antibody can be used to monitor response to therapy

TPPA readings

2+ = most reactive

— = non reactive

Treatments for treponemal infections (syph)

Antibiotics:

• penicillin G for all tropenemal infections

• Doxycycline prescirbed if penicillin allergy

• caries on disease and age of host

Yaws

Endemeic in africa, south merica : primary stage lesion s- elevated, granulomatus nodules

Endemic syphillis or bejel

middle east arid

primary / secondary lesions - papules

progress to gummas of skin and bones and nasophaynx

Pinta

tropical central south america

person to person

scaling, painless papules —> erythematous rash becomes hyperpigmented over time

Borrelia properties

highly flexible spiralis : 3-10

actively motile : 15-20 flagella per cell

stains well with giemsa bright field

Borllia diseases

Relapsing fever

• lice B. recurrentis

• tick - b. duttonii

lyme disease

• tick b.burgdorferi

Endemic relapsing fever

b. recurrentis lice (louse)

episodic symptoms due to antigenic variability (changes surface markers) —> confuses immune system

Epidemiology boriella

ferbile period : 3-7 days

aferbile period : days - weeks

Borellia cultivation

culture on Barbour stoener kelly medium (rare)

perferred done on serum

Wet preps from periphereal blood of febrile patients

antigenic variation —> serology impractical , very challenging for a serological test diagnosis if it changes

Boreiella treatment

treated with tetracyclines which reduce rate of relapse and kill abcteria in CNS

side effect : Jarsich herxheimer reactions

• due to release of toxic or antigenic substances by the ifnecting microbe

Lyme disease

associated with B. burgdorferi

Transmitted to humans via bite of lxodes tick

most common disease in North american and europe

tick attatched > 24 hrs = disease transmitted

IgM antibodies are continually produced and can be detected months / years after infection bc of antigenic variation

Lyme disease stages

First stage: erythema migrans : red ring, headache, fever, muscle pain

Second stage: weels to months after infection : neurologic disorders , arthritis

third stage : characterized by chronic arthitiris may continue for years

Third stage chronic lyme disease

acute pahse symptoms : skin rash flu like synmptoms

can be resolved by immune response or abx tresament

resulting autoimmunity

molecular mimicry phenomenom

pathoen has a molecule taht reswmbles a host moleculte

chronic lyme disease definition

autoimmuni disease rxn that can cause persisitant arthritis and neurologic sympotms even after abx treatment

Molecular mimcry phenomenom

conditions that pathogen caontains a molecule that resmbnles host molcule

when immube cells attack the pathogen, the look aliek cells also get attacked, resultign in damage to hsot

B.burgdorferi diagnosis

organism visible in tissue sections, ususally very few number of organisms

PCR more effective than microscope to find in early and late phases

IFA, ELISA, Western Blot used

speci : urine, synovial fluid

Primary screening method to ddetect Borrelia

ELISA, to detect antibody against borellia

false positive are high from cross reactivity

2 step serologic approach

Screen with ELISA or IFA

Confirm result using imunoblotting

Borrelia treatment (lyme disease)

susceptiblity testing ususally not performed,

First stage treated with deoxycycline, amoxcillian, cerfuroxime

late stage treated with broad spectrum cephalsopsrins (ceftriaxone or cefotaxime)

Leptospira interrogans

chain of cocci

ends have hooks

Zoonotic disease, shed in water and mud in urine of infected animasl

Enter human host by small cuts of skin or swallowing water

Weil Disease

weil disease

Leptospira interrogans

heptatic, renal and intravasulcar disease

Doxycycline is druge of choice, vaccination for pets

Weil disease stages

first stage 4-7 days : conjuctival suffusion , leptospiremia

Second phase (unsure) neurological lesions

Leptospirma lab diagnosis

Blood and CSF plated on Fletcher, stuart, EMJH media, incubated at dark room temp.

Macroscopic aggulitantio test and gold standard microscopic aggultination test for anitbodies

Mycobacteria general cahracteristics

non spre forming

non motile

slwo growing

Acid fast cell wall

very high lipid content

Habitiat of mycobacteria in humans

Person to person

M.tuberculosis complex: one meber of complex infects animals

M.leprae : non cultureable

habitat of mycobacteria in enviroemental

NTM: Non tuberculosis mycobacteria

Water of soil

oppurtuistc

Mycobacterium 2 main groups

Mycobacterium tuberculosis complex

non tuberculosis myco bacteria

2 groups of non tuberculosis mycobacteria

slow growing

fast growing

Mycobacterium tuberculosis complex

capable of casuing tuberculosis

slwo growing , forms nonpigemnts colonies

tranmission from droplets

Mycobacterium tuberculosis complex pathogeneis

inhalation of a SINGLE organism can lead to infection

Quaniterfon tests for latent TB

Mycobacteria bovis

associated with milk form infected cows

BCG vaccine, used to immunize tb

individuals with HIV are more prone

Tb skin test

not reliable in countried with high cases, cross contamiation

Mantoux test (the skin test) : mesurement of delayed type hyper sensntivity to PPD antigen (purified protein derivative)

Tb skin test interptration

Pos : exposure to M. tuberculosis or BCG vaccine

Neg: no exposure, loss of reactivy with time or severe disease, immunosupporesion

quantiferon tubes

measures (interferon y) IFNy by enzyme linked immuno absorbant assay (ELISA) is used to identify in votro response

usues peptides to stimulate tb proteins to stimulate cells in whole blood

Tb pathogensis

Primary : droplet aiborne

tb is ingested by alveoli macrophages