Spirochetes Flashcards
Spirochetes shape, location , differences, how to view
long, slender, spiral- shaped bacteria
can be free living or host associated
sound in human oral cavity, GI tracts of humans, mammals, insects & in marine environments
motile
differ by their number & tightness of their spirals
typically require special stains
may be viewed in wet-mounts with dark-field or phase contract microscops
Spirochetes Borrelia spp.
spirochetes that are transmitted by arthropods ( ex. ticks& lice)
- all pathogenic Borrelia are arthropod-bourne
Lyme Borrelia infection state ( 3 stages)
includes B.burgdorferi, B.garinii, B.afzelii
Lyme disease ( lyme borreliosis)
stage 1: fever, headache, malaise & muscle pain
- 60% of patients present with a target lesion
stage 2: disease spreads throughout the body
- may cause arthritis, meningitis or myocarditis ( can last weeks-months)
Stage 3: chronic arthritis, neurologic defects or skin lesions
Lyme disease transmission
bacteria infects rodent & dear
bacteria is transmitted to ticks
infection spreads to humans after bite from infected tick
Lyme disease Identification
serological tests
- detects antibodies
- prone to false + & -
direct macroscopic
- lyme spirochetes may be stained with Giemsa & special silver stains
- insensitive test due to hoe low number of bacteria are present in specimen
cultures
- preformed by reference lab
- cultivated using kelly medium
Lyme disease treatment
macrolides, doxycycline & amoxicillin - effective for early stage of disease
ceftriaxone- effective for late stage of disease
** early diagnosis & antimicrobial treatment are important for preventing neurologic, cardiac & joint abnormalities that may occur late in the disease
Relapsing fever Borrelia ( B. recurrentis) infection state
relapsing fever : repeated episode of spirochetemia ( spirochetes in the blood) which causes acute febrile episodes that subside spontaneously but tend to recur
- fever, headache & muscle pain
- hosts immune system responds to end episode
- spirochete is capable of chamging surface antigens
- new variants cause a new febrile episode & the hosts immune system responds once again
- cycle can be repeated up to 10 times
B.recurrentis transmission
Louse-borne
- epidemic relapsining fever
- only in humans
- transmitted by body lice
- louse is infected with B. recurrentis
Tick-bourne
- epidemic relapsing fever
- Transmooted by ticks
- tick is infected by a number of Borrelia spp.
B.recurrentis Identification
microscopic
- blood samples collected during febrile episode
- blood smear stained with Giemsa or Wright stain
- Only spirochete which is visible in blood smear with a bright field microscope
- wet preps can be examined with dark field or phase contrast
cultures
-bacteria may be cultured on special media however rarely done
B.recurrentis treatment
borreliae are susceptible to many antimicrobial agents
tetracyclines are the drugs of choice
- Reduce the relapse rate
- ride the CNS of spirochetes
Treponema Pallidium disease & how its contracted
causes venereal syphillis
bacteria transmitted through
- sexual contact ( most common) - with someone who has an active primary or
secondary syphilitic lesion
-Transplacental ( through the placenta)
- Contact with non-genital syphilitic lesions ( mouth, skin)
- Blood transfusions ( blood donors are screened)
Treponema Pallidium general facts
can infect almost ant organ system
can co-exist with HIV & result in variation of the natural course of the disease
ulcers caused by syphilis may contribute to the efficiency of HIV transmission in populations with high rates of both infections
syphilis is named “ great imitatior “ due to the wide variety of clinical manifestations
primary syphilis
inflammatory reaction creates an ulcerated ulcer (chancre) at inoculation site
Chancre - firm painless lesion that contains many spirochetes
highly infectious
this stage lasts from 3 to 6 weeks
** note: Chancre is T.pallidium subsp.Pallidium
Chancroid is caused by Haemophilus ducreyi
Secondary syphilis
Organism spreads throughout body
characterized by widespread body rash , lymphadenopathy, fever & malaise
skin & mucus membrane lesions contain numerous spirochetes & are highly infectious
lasts for period up to 2-3 months
latent syphilis
asymptomatic stage
described as either early ( less than 1 year after secondary syphilis ) or late ( more than 1 yr after secondary syphilis )
diagnosed through serological test
may last indefinitely 1/3 of untreated cases)
may develop into tertiary syphilis ( 1/3 of untreated cases)
may exhibit biological cure ( 1/3 of untreated cases)
Tertiary ( late) syphilis
subclinical stage where the disease remains dormant & cause complications of the CNS & cardiovascular system
may also affect skin, liver & bones
occurs later in life ( 5-25 yrs after initial infection)
patients not usually infectious at this stage
Gummas
Syphilis can casue Gummas
- localized areas of granulomatous inflammation on bones, skin & subcutaneous tissue
cutaneous gummas may be singel or multiple
generally asymmetric & grouped together
visceral lesions often cause local destruction of the affected organ
Congenital Syphilis
occurs when the bacteria cross the placenta & infect the fetus
may cause fetal death
mau cause birth defects
late onset can occur ( after 2 yrs of age) casuing interstitial keratisis, bone & tooth deformities, cranial nerve deafness, neurosyphilis & other tertiary manifestations
may be prevented if pregnant women are screened & treated
T.pallidium Nontreponemal tests
detect antibodies against lipids released during a syphilitic infection
sensitive but non-specific testing
test is often positive in primary syphilis & almost in secondary syphilis
detect the anti-lipid antibodies though a clumping reaction ( suspended)
ex. Venereal disease research laboratory(VDRL)
T.pallidium Treponemal tests
Used to confirm nontreponemaal tests
detetcts treponemal antibodies
test is often positive in primary syphilis & almost always positive in secondary syphilis
ex. fluorescent treponemal antibody absorption (FTA-ABS) tests Microhemagglutination Assay for Treponema pallidium Antibodies (MHA-TP)
T. Pallidium microscopy
fluid collected from primary & secondary lesions & exaamined under darkfield or phase contrast
tightly coiled spirochetes exhibiting corkscrew motility
measure 0.1 µm in diameter nu 6-20 µm in length
specimen should be examined within 20 mins of collection
oral lesion material not recommended due to the “nonpathogenic” treponemes that may be present
T. pallidium DFA tests
may be done on skin lesions, tissues , body fluids & mucosal lesions of the mouth , nose & intestines
T.pallidium ( syphilis) treatment
penicillin
- drug of choice
- long acting benzathine penicillin is preferred
- no known resistance
doxycycline & tetracycline can be used for penicillin allergies
