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)
