Term
2 serious bacterial pathogens of URI |
|
Definition
Bordetella spp
Haemophilus influenzae |
|
|
Term
5 pathogenic species of Bordetella |
|
Definition
B.avium
B.bronchiseptica
B parapertussis
B. homesii
Bordetella pertussis |
|
|
Term
|
Definition
|
|
Term
Bordetella bronchiseptica
|
|
Definition
kennel cough-dogs
necrotic rhinitis-pigs
URT-humans |
|
|
Term
|
Definition
mild whooping cough
human |
|
|
Term
|
Definition
pneumonia, bacteremia (newly emerging) |
|
|
Term
|
Definition
extremely small gran neg coccobacilli
strictly aerobic
obligate human pathogen-NO animal reservoir (unlike Salmonella enteridits)
Fastidious, slow growing-3 to 6 days for colonies of Border-Gengou agar
infects the URT-cilliated respiratory epithelium
elaborates powerful toxins which elicit most of the sx of the dx
pertussis means violent cough-assoc w/ whooping cough
DPT vaccine |
|
|
Term
DX Bordetella pertussis (4 ways) |
|
Definition
1.culture bacteria from respiratory secretions (not always successful)-viable, but non culturable bacteria (VBNC) ex-can't use cotton swabs for sampling the throat b/c fatty acids in cotton kill the B pertussis bacteria
2. immunofluorescense assay on secretions-antibodies that recognize pertussis proteins
3. agglutination reaction on secretions-antibodies that recognize pertussis proteins
4.dx based on clinical dx-whoop-type coughing and lymphocytosis
|
|
|
Term
|
Definition
worldwide problem-60 million cases, 600,000 deaths/yr
developed countries-dreamatic increase in cases with decreased vaccine use, rise of strains resistant to the vaccine |
|
|
Term
transmission/infection patterns B. pertussis
(4 things) |
|
Definition
**Highly contagious-attack rates of 50-100%
transmission-aerosol droplets from coughing
females-higher attack rate, morbidity, mortality, don't know reason for this
age distrubution-recent shifts in age groups |
|
|
Term
shift in age distribution of infection |
|
Definition
prevaccine-predominately infected young children (1-3 years of age)
post vaccine-inc rate of infection in 2 groups (older children 5 to 14; young adults 18-25)
vaccines exert strong selective pressures on pathogens
selects for outgrowth of variants for which the vaccine doesn't evoke immune protection
vaccination has "pushed" bacterium into other age groups-fewer maternal antibodies remaining in older children, protection by vaccination in young children is not lifelong |
|
|
Term
virulence factors of bordetella pertussis |
|
Definition
binds to ciliated epithelium of URT
multiple adhesions
multiple toxins |
|
|
Term
name the four adhesins of B pertussis |
|
Definition
pili-attachement to host cells
filamentous hemagglutinin-adherance to glycolipids-predominat in eukaryotic cells
capsule-antiphagocytic, adherence
pertacin-binds to host cells
|
|
|
Term
name the 6 toxins of B pertussis |
|
Definition
pertussis toxin
adenylate cyclase toxin
lymphocytosis-promoting toxin
tracheal cytotoxin
dermonectrotic toxin
LPS (enterotoxin) |
|
|
Term
Pertussis toxin of B Pertussis |
|
Definition
A1-B5 class of toxin (similar to CT)
B pentamer-binding to receptors on cells
A polypeptide-enzyme which increases cAMP |
|
|
Term
adenylate cyclase toxin of B pertussis |
|
Definition
increases cAMP in infected URT cells |
|
|
Term
lymphocytosis promoting toxin of B pertussis |
|
Definition
increases lymphocyte numbers in URT |
|
|
Term
tracheal cytotoxin of B pertussis |
|
Definition
may be the actual major virulence factor (as opposed to the pertussis toxin)
fragment of peptioglycan cell wall
destroys ciliated epithelial cell walls
diff from other toxins-struc component on cell wall-cleaves and destroys the cell wall |
|
|
Term
dermonecrotic toxin of B pertussis |
|
Definition
causes skin lesions and fatality in mice but not known to have effect in humans |
|
|
Term
LPS endotoxin of B pertussis |
|
Definition
activates alternative complement pathway
fever |
|
|
Term
3 stages of B Pertussis infection |
|
Definition
1. incubation stage
2. catarrhal or prodomal stage
3. paroxysmal stage |
|
|
Term
Incubations Stage Bordetella Pertussis |
|
Definition
no overt symptoms
lasts 7 to 10 days
infected indiv is already infectious |
|
|
Term
catarrhal or prodomal stage bordetalla pertussis |
|
Definition
lasts from 7 to 14 days
non specific sx-makes it east to mis dx
malaise, rhinorrhea, lacrimation, low grade fever, (cold of flu like)
dry cough develops, worse at night |
|
|
Term
paraoxsymal stage B pertussis
|
|
Definition
paroxysmal coughing-tenacious mucus, series of repetitive coughs followed by a charac inspiratory "whoop" (cyanosis, convulsions, seizures)
px looks normal b/w paraoxysms w/ minimal fever
cillistatis-death of URT cilliated epithelial cells (tracheal cytotoxin), failure of respiratory escalator to move mucus from lungs to throat
lymphocytosis-neutrophil count in the tissues to 200,000 cells/ml
persistance-sx last 1-2 weeks, until ciliated cells redifferntiate from basal cells
erythromicin-doesn't alleviate sx bc cells are already dead
convalescene (3-4 weeks); lymphocytes dec gradually, cough subsides
|
|
|
Term
3 locations of haemophilis influenzae |
|
Definition
upper respiratory tract
lower respiratory tract
middle ear |
|
|
Term
haemophilis influenzae features |
|
Definition
aerobic gram neg bacterium
coccobacillus or pleomorphic rods
obligate human pathogen
may be encapsulated or non encapsulated
required for growth-fastidious bacterium to culture, hemin, nicotinamide adenine dinucleotide (NAD)
chocolate agar-contains heat treated lysed erythrocytes |
|
|
Term
virulence factors of H influenzae |
|
Definition
capsule-secreted polysacch "coat", antiphagocytic activity, resisits killin macrophages and polymorphonuclear neutrophils
pilus-rod like appendage, promotes attachment to target cells of URT or middle ear
HAP protein-surface protein-promotes more intimate adhearance of baceterium to cells
endotoxins-LPS inflammatory, pyrogenic (fever), impairs cilliary func or URT cells
IgA1 proteases, destroys IgA, facillitates colonization of the mucosal surfaces |
|
|
Term
How do we differentiate b/w strains of haemophilis influenzae? |
|
Definition
6 serotypes based on antigenic differnces in capsular polysaccharides
Serotype A, B, C... |
|
|
Term
Serotype B Haemophilis influenzae |
|
Definition
most prominent disease causing strain in US in prior decades
VERY effective vaccine-worked well for a while
based on Sero B capsular polysacch |
|
|
Term
2 commonly identified serotypes that cause diease of H. influenzae |
|
Definition
|
|
Term
|
Definition
after widespread use of vaccine-most infections caused by unencapsulated strains
emerged as prominent cause of otitis media since the advent of the Hib vaccine
colonized the nasopharynx-many healthy children and adults
approx 8-10 mill cases/year in US
colonized LRT-adults with COPD
colonization early in life assoc w/ recurrent otitis media-middle ear infections |
|
|
Term
NTHI associated Otitis Media |
|
Definition
NTHI attaches to mucosa of throat using various adhesions
bacteria replicate in throat causing localized URT infections
throat-eutacian tube-nasopharynx-middle ear
replicated in middle ear-pure cultures of bacteria can be obtained from otic fluid
release of bacterial factors cause severe inflammatory response-acute pain, fever, potenial loss of hearing, usually not a lethal infection (meningitis) |
|
|
Term
|
Definition
another spp of haemophilus is correlated a higher probability of contacting a lethal disease
causitive agent for chancroid genital ulcer disease-breaks in skin
risk factor for aquisition of HIV, requires breaks in the skin to enter the body, infection was widespread in parts of Africa
|
|
|
Term
pathogens and increased risk of other pathogens
|
|
Definition
contracting one pathogen may make you much more suseptible to infection by another pathogen or disease
hemophilus ducreyi-HIV
H. pylori-gastric carcinoma
Viral influenza (flu)-N. meningitis
pathogens evolve or adapt to take advantage of newly opened ecological niches w/in body |
|
|
Term
|
Definition
genus: mycobacterium
species: mycobacterium tuberculosis
mycobacterium avium-intracellulare (MAI complex)
mycobacterium leprae |
|
|
Term
three mycobacterium diseases |
|
Definition
1. tubercule bacilli-TB (M. tuberculosis)
2. MOTT of Atypicals-M avium-intracellulare
3. Leprae-leprosy or Hansen's disease (m. leprae) |
|
|
Term
mycobacterium and high lipid count |
|
Definition
have high lipid count
cell wall is a complex layered complex
peptidoglycan skeleton overlayed with layers of lipid
primary lipid-mycolic acid
lipid accounts for about 40% of dry weight of the cell |
|
|
Term
5 traits of cell wall comp responsible for distinguishing traits of bacteria |
|
Definition
acid fastness
slow growth
resistance to disinfectant and strains
resistance to common antibacterial antibiotics
antigenicity-surface glycolipids |
|
|
Term
mycobacteria as acid fast bacilli |
|
Definition
ziehl neelsen procedure-acid fast stain (carbol-fuchsin) is forced by heat or detergent into cell
Bacterium resists acid alcohol decolorization and retains red color of acid fast stain
not able to be stained by gram stain raegents |
|
|
Term
3 general characterisitcs of mycobacteriym |
|
Definition
1. high lipid content
2. acid fast bacilli
3. slow growth rate |
|
|
Term
slow growth rate of mycobacterium |
|
Definition
generation time-12-20 hours; 30 minute gen time for E. Coli
slow growth rate due to complex lipid-rich cell wall |
|
|
Term
microscopic morphological appearance of mycobacterium |
|
Definition
acid fast bacilli (AFB)
non spore former
non motile
no capsule |
|
|
Term
growth conditions mycobacterium
colony appearance |
|
Definition
obligate aerobe
simple growth medium-inorganic salts, asparagine, and glycerol
selective media, lowenstein 7H-10 or Middlebrook 7-11
colony appearance is extremely rough/dry colonies |
|
|
Term
magnitude of infection Tubercle Bacilli (M. tuberculosis-human strain) |
|
Definition
1.immunity host
2. hypersensitivity host
3. infecting dose bacilli |
|
|
Term
brief vs. chronic tb infections |
|
Definition
brief-asymptomatic incident
chronic-progressive lung dx resulting in loss of almost all func lung tissue |
|
|
Term
|
Definition
close person to person contact
inhalation of infectious aerosols |
|
|
Term
3 types of clincial TB dx |
|
Definition
1. primary TB-direct course (recent infection)
2. secondary TB (reactivation or reinfection)-activation of a latent infection, "new" direct course
3.disseminated TB-extrapulmonary TB-non pulmonary infections |
|
|
Term
|
Definition
respiratory dx
infections restricted to lung or lower RT |
|
|
Term
8 steps of TB primary infection |
|
Definition
1. inhalation bacilli
2. phagocytosis by avelor macrophages
3. growth of bacilli intraceullarly w/in macrophages (prescense of sulfatides)
4.exudative lesions or primary lesions
5.productive lesions
6.productive lesion expansion
7. caseous lesion
8. entry bacilli into bloodstream |
|
|
Term
growth of bacilli intracellarly w/in macrophages in primary TB infection |
|
Definition
prescnce of sulfatides
sulfatides func w/ inhibition of phagsome lysosome fusion; increases bacterial survival when phagocytosed
infected phagocytic cells burst releasing bacilli allowing further cycles of phagocytosis-lysosome mycobacterial replication and cell lysis |
|
|
Term
exudative lesions or primary lesions in primary TB |
|
Definition
early part of infection
exudative lesions-charac by presence of poly morphonuclear leukocytes, fluid and inflammation
most bacilli growing intracellularly in macrophages
lesion may heal-reabsorption of inflammatory derived exudates |
|
|
Term
productive lesions "tubercles" in primary TB |
|
Definition
3 to 4 weeks after infections, host develops cellular immunity or allergy to the bacilli
large influx of mononuclear cells into lungs-formation of specific infection sites or tubercles
tubercle appears oas a granular nodule (granuloma)-host's mech for inhibiting bacillary multiplication
housed w/in tubercles are bacilli which can be reactivated
tubercles may harbor bacteria indefinitely
formation of tubercles or granulomas walls off lesions from healthy tissue |
|
|
Term
|
Definition
solid mass or nodule
central core-TB bacilli and enlarged macrophages
outer wall-fibroblasts, lymphocytes and neutrophils |
|
|
Term
productive lesion expansion in primary TB |
|
Definition
neutrophils at lesion site release lysosomal enzymes that destroy tubercle (necrotic tissue), healthy tissue and some bacilli (allows lesion to expand)
caseation necrosis-semi solid coagulated mass (cheesy state) of host cells and bacilli
|
|
|
Term
caseous lesion of primary TB |
|
Definition
can heal-calcification; infiltration of fibrous tissue and Ca deposits
or expansion of caseous lesion-resulting in cavities in lung after clearance of necrotic tissue |
|
|
Term
entry of bacilli into bloodstream in primary TB |
|
Definition
lesion epxansion involves portal vein
infectivity of other organs and tissues; bone marros, spleen, kidneys, and CNS |
|
|
Term
2 possibilities with secondary TB |
|
Definition
reactivation of bacilli from an "earlier" infection
reinfection of "new" bacilli from the environment |
|
|
Term
reactivation of primary infection in secondary TB |
|
Definition
represents 2/3 of all "new" active cases of TB
residing w/in tubercle or "healed" primary lesions are dormant bacilli
bacilli reactive: dec immunological capabilities
1.elderly or young adults
2. immunosuppressive disease
3. chronic alcoholism
4. prolonged corticosteriod therapy |
|
|
Term
2 types of disseminated TB |
|
Definition
1. lung lesions-entry of bacilli into bloodstream
or
2. lymph sytem-possible infection of every organ |
|
|
Term
organs most commonly involved in a TB infection |
|
Definition
regional lymph nodes, kidneys, gential tract, CNS, long bones/weight bearing joints,
miliary TB-numerous small tubercles in body tissues-"millet seed" lesions |
|
|
Term
|
Definition
non specidic, malaise, weight loss, cough, night sweats |
|
|
Term
|
Definition
violent coughing, chest pain greenish or bloody sputum, extreme fatigue |
|
|
Term
|
Definition
infection by TB bacillis, delayed hypersensitivity reac
intensity of hypersensitivy response; amount of mycobacterial antigen in the host
tuberculin Ag (mycobacterial Ag) |
|
|
Term
|
Definition
ability of macrophages to kill bacilli or inhibit growth-activated macrophages, killing/inhibition
T cell sensitivity-not life long
nursing home studies
immunocompetent elderly-one time Tuberculin (+)
may become non reactive-risk of contracting a primary infec |
|
|
Term
|
Definition
1. tuberculin testing-pos skin test reactivity
2.roentgenography-chest x rays (checking for tubercle or destroyed skin)
3. lab detection, microscopy, culture |
|
|
Term
TB testing-skin sensitivity test |
|
Definition
tuberculin antigen-purified protein deriviative (PPD)-surface glycolipid from the myobacterium's cell wall |
|
|
Term
|
Definition
inject 5 tuberculin units of PPD intradermally in forearm
measure size of induration (hardness) after 48 and 72 hours, degree of induration at site of injection is an indication of indiv present or past assoc w/ TB |
|
|
Term
hypersensitive indiv and TB |
|
Definition
tuberculin evokes an intense inflammatory reaction (delayed hypersensitivity) at site of injection observed as an induration with erythema (redness) and edema, hypersensitity may exist throughout life |
|
|
Term
|
Definition
**inidicates prior contact with mycobacterial proteins but not neccesarily the active disease |
|
|
Term
roentgenography chest x rays and TB |
|
Definition
tubercular infections-abnormal radiopaque patch
looking for tubercle or lung caberation |
|
|
Term
|
Definition
microscopy-clincial source of infecting bacilli, TB-sputum or lung secretions, disseminated TB-CSF, urine, joint material, or feces
direct identification of AFB-1.ziehl Neelson stain; 2. fluorescent acid-fast stain (smear eval-#AFB/field, culure-accurate species ID)
selective media-lowenstein Jensen or Middlebrook 7H10 or 7H11-prob 3 to 4 weeks colony detection, biochem tests-production of niacin, catalase, and nitrate reductase |
|
|
Term
rapid means of species ID and TB |
|
Definition
nucleic acid probes-DNA probes
chromatographic analysis of cell wall lipids by HPLC (high performance liquid chromatography) |
|
|
Term
|
Definition
1. no hospitalization-past paitents were quarantied in sanatoriums
2.prolonged antibioitic therapy (6 to 24 months) chronic nature, tow months of isoniazid, rifampin, and pyrazinamide
four months daily or weekly doses of rifampin and isoniazid
combined anitbiotics to avoid drug resistance
inc period of therapy in px w/ HIV |
|
|
Term
long period of antibiotic therapy and TB |
|
Definition
many organisms are intracellular (hiding in macrophages)
rate of metab is slow
chemotherapeutic drug does not easily penetrate the fibrotic or caseous lesions |
|
|
Term
outbreaks multi drug resistant TB |
|
Definition
failure to follow prescribed drug regimens (1990 to present) primarily AIDS px, homeless in NYC and miami |
|
|
Term
higher rates of infection of TB |
|
Definition
homeless, recent immigrants, drug addicts, AIDS px
nosocomial transmissions, AIDS px, w/ muilti drug resistant TB
highest case rate-non white males over 30, nonwhite females over 60
NYC-highest case rate, reporting 10% of all cases in US |
|
|
Term
|
Definition
1. family members of recently dx cases receive isoniazid chemoprophylaxis for 1 year
2. tuberculin skin testing screening-hospital workers
3. vaccination-attenuated bacille calmet guerin BCG, isolated from M bovis, immunize neg tuberculin reactors, vaccination of young children in countries w/ high rates TB, offers 20-80% protection for several years, not used in US since it induces a pos TB test |
|
|
Term
|
Definition
difficult, slow chronic dx diff to isolate people until months or years after infection,
px non compliance w/ therapy, immigrants, homeless, substance abuse, mental illness, or socioeconomic probs
|
|
|
Term
|
Definition
mycobacteria other than tubercle bacilli
M avium-intracellulare complex (MAI)-two species diff to tell apart so its a "complex"
originally assoc w/ compromised pulmonary func (chronic bronchitis), clinically identical to pulmonary TB
|
|
|
Term
MOTT risk groups, transmission, pathogenesis
|
|
Definition
risk groups-1990's AIDS px, terminal stages
transmission-ingestion of contaminated food or water
pathogenesis-mycobacteria multiply in lymph nodes-spread systemically, disseminated mycobacterial infection |
|
|
Term
organ involvement, transmission, prognosis of MOTT |
|
Definition
organ involvement-die of mass organ failure from bacterial engorged organs, bacilli flood blood stream, bone marrow, bronchi, intestine, kidney, and liver
tx-antibiotic therapy-clarithrmycin, ethambutal, and rifabutin
prognosis-poor, mass bacilli impair organ func
**third most common cause of death in AIDS px |
|
|
Term
Leprae, leprosy or Hansen's disease (M. leprae) |
|
Definition
distinguising charac: strict intracellular parasite, not cultivated in vitro; no growth artificial media
cultivated in vivo-mouse foot pads or armidillos
very slow growth; generation time-12 days |
|
|
Term
|
Definition
person to person spread by inhalation or direct contact of lesions
1. inhalation of bacilli onto nasal mucosa
2. direct skin to skin contact (intact skin or penetrating wound) with respiratory secretions or wound exudates |
|
|
Term
|
Definition
entry-inhalation or skin contact
phagocytosed by macrophages
(4-12%) of infected indiv have weak macrophages-intraceullar survival
incubation is 2-5 years
infection-chronic progressive diease of skin and peripheral nerves that often leads to disfigurement |
|
|
Term
|
Definition
1.indeterminate or borderline leprosy
2.tuberculoid leprosy
3.lepromatous leprosy |
|
|
Term
indeterminate or borderline leprosy |
|
Definition
intial sx-few hypopigmented areas of the skin plus a dermatitis
severe residual sx-damage to nerves that control muscles of hands and feet, subsequent wasting of muscles and loss of control-drop foot or claw hands |
|
|
Term
|
Definition
1.dependent on tx
2.dependent on immunological competence of indiv |
|
|
Term
|
Definition
most indiv recover spontaneosly
dev of either tuberculoid or lepromatous leprosy |
|
|
Term
2 major clinical forms of leprosy |
|
Definition
tuberculoid leprosy
lepromatous leprosy |
|
|
Term
|
Definition
sx-1 to 3 shallow skin lesions, lesions are blanced, appear flat, contain few bacilli, localized areas of anesthesia (nerve damage), nerve damage as a result of inflammation that occurs during a cellular immune response to bacilli in the nerves (numbness or anesthesia) happens from local inflammation reaction
recovery is frequently self limiting |
|
|
Term
|
Definition
accountable for dx assoc disfiguration
degrees of disfigure; max resistance-disease affects superficial nerve endings and related skin areas or minimal resistance w/ organ involvement in eyes, testicles, and bones |
|
|
Term
sx of lepromatous leprosy |
|
Definition
early sx-small hypopigmented spotty lesions, numbness-hands and feet, loss of heat and cold sensibility, muscle weakness, chronic stuffy nose, thickened earlobes
later sx-diffuse to nodular lesions or lepromas (granulomatous thickenings w/ folds) result of massive intracellular overgrowth
lesion location-cooler parts of body, nose, ears, eyebrows, anterior third of eye, peripheral nerves at speicific sites, elbow wrist, ankle (optimum growth 30 deg) irreversible peripheral nerve damage-loss of feeling and permanent paralysis
secondary sx-trauma and mutilation to self-sensory loss-can't feel pain
untreated-death by kidney or respiratory failure |
|
|
Term
increased susceptibility and leprosy |
|
Definition
health pre disposing risk factor-inherited or acquired defect in cell mediated immunity
living conditions-long term household contact w/ leprotics, poor nutrition, crowded conditons, inadequate hygeine |
|
|
Term
|
Definition
prescence of skin lesions and nodules consistent w/ clinical dx
non culturable AFB in lesions (nasal discharges, tissue samples, and nodules)
neurological eval of extemetities-occurance of anasthesia, feather test
lepronin skin test-no aid in diag, lepromatous px-impaired cullular immune response and will not react
most indiv test pos to lepronin |
|
|
Term
|
Definition
combined antibiotic therapy-dapsone, rifampin, clofazimine, or ethinamide for a min of 2 years
pilot vaccine study-antileprosy studies in india; ICRC bacillus-vaccine is a killed leprosy bacilli from a human leproma
prevention w/ surveillance of high risk populations to discover early cases, chemoprophylaxis of healthy persons in close contact w/ leprotics, isolation of leprosy px |
|
|
Term
points of interst w/ TB and leprosy |
|
Definition
1/3 of worlds pop infected w/ TB bacillis
WHO declared TB global emergency
TB kills approx 2 mill people each year
each year there are 600,000 new cases of leprosy |
|
|
Term
|
Definition
organsims that lives on or in host org and gets its food from or at expense of host
often pathologcial but not always |
|
|
Term
common parasitic dx in the US |
|
Definition
toxoplasmosis
giardiasis
pinworms
crtosporidum diareha
trichomonas vaginitis
imported malaria |
|
|
Term
|
Definition
living together of organisms w/o harm to each other |
|
|
Term
|
Definition
coexisitence in which both organisms can benefit from the arrangement |
|
|
Term
|
Definition
coexistence in which one partner (the parasite) has the potential to harm the other (host) |
|
|
Term
|
Definition
speicies in which parasite undergoes sexual reporduction |
|
|
Term
|
Definition
species in which a part or whole of a an asexual reproduction occurs |
|
|
Term
|
Definition
unnatural host to which the parasite may not be adopted for replication
unusal pathology |
|
|
Term
|
Definition
insect to human transition |
|
|
Term
unicellular parasites (protazoa, protists) |
|
Definition
phylum sarcomastigophora
phylum apicomplexa |
|
|
Term
sub phylums under phylum sarcomastigophora |
|
Definition
subphylum sarcodina
subphylum mastiogphora |
|
|
Term
|
Definition
under subphylum sarcodina
agents of amebiasis
worldwide distribution, many infected, many more carriers
confusion w/ morphologically similar but non invasive species E dispair
E histolytica specific antigen and PCR tests avail to distinguish the cysts from E dispar |
|
|
Term
lifecycle of E histolytica |
|
Definition
2 stages
1.cyst stage passed out in fece, many parasites use this
2.trophozites stage passed in gut
fecal oral route of transmission |
|
|
Term
E histolytica trophozites |
|
Definition
replicative stage:heat labile
**Pathogenic stage
about 20-30 million micron motile forms (ameboid)
No mitochondria, have mitosomes
phagocytosis of bacteria and red cells
secretion of various cytocidal agents
"amebapore" small peptides (77aa) that form a pore in cell membranes |
|
|
Term
|
Definition
trophozites differentiate into cysts (encystation)-formation of cysts
differentiation happens during passage through gut (changes in pH, cholesterol etc)
infectious cyst stage of the parasite can tolerate 55deg C, cholride levels of city water supply and normal levels of the gastric acid |
|
|
Term
|
Definition
large number of people infected (1-10%) carriers estimated
about 10 percent of infected individuals go on to get invasive pathology
fecal-oral spread, veneral transmission also seen
incidence in US when up as AIDS epidemic started |
|
|
Term
E histolytica pathogenesis |
|
Definition
humans are main reservoir (millions of cysts can be passed in stools of infected indiv)
transmission by cysts
cyst wall disintegrates in distal small intestine and eight trophozoites are released per cyst
tropozites colonize large intestine
adhere to host cell through specific lectinss and secrete pore forming peptides that lyse cells
secrete various enzymes (proteases, collagenase)
induction of mucosal ulcers
acute inflammatory response, diareha, flatulence, and cramps,
chonic amebiassis can last for months for years (can have it for a while w/o even realizing what it is) |
|
|
Term
extraintestinal amebiasis |
|
Definition
hepatic (liver) absess seen in about 5% of the cases-more common in adult males
absesses can extend into surrounding tissues, pneumonia, periontitis, chornic pericardial infection
in rare cases go to lungs and brain |
|
|
Term
amebiasis dx and treatment |
|
Definition
stool examination of wet mouths to observe cysts and tropozites
enzyme linked immunoassays and PCR avail
tx diferent drugs avail to tx amebiassis depending on the stage and severity but generally good to tx |
|
|