Exam2Lec5ICBacteria Flashcards
How do intracellular pathogens get inside the cell?
Taken up by cell and create a endosome or phagosome
1. can escape endosome
2. prevent fusion with lysosomes so they cannot be broken down
3. fuse with lysosomes to form phagolysosome but survive in the phagolysosome
How do the intracellular bacteria get around?
ACTIN ROCKET
The bacteria hack the cytoskeleton and begin an actin tail assembly to be motile. Once motile with actin tail they can push to other cells
What are the facultative intracellular bacteria talked about in class?
Mycobacterium tuberculosis
Bartonella henselae
What are the general characteristics of the genus mycobacterium?
aerobic, gram + rods
Acid fast:
—- bind phenol-based dyes in presence of heat
—–retain dye when treated with acidified alcohol
How does acid fast work?
-bind phenol-based dyes in presence of heat
-retain dye when treated with acidified alcohol
why do we have to do an acid fast stain on Mycobacterium?
Complex cell wall lipids
-include mycolic acids–>waxy envelope so it is hard to penetrate
What is the growth speed of Genus mycobacterium?
VERY SLOW ~3 weeks to grow from small inoculate
Extra:
- Generation time:
—–15 - 20 min for E. coli
—– 60 min for C. diphtheriae
—— 300 min for M. tuberculosis
What is included in the complex cell wall lips of genus mycobacterium?
mycolic acids
The waxy layer or complex cell wall lipid of genus mycobacterium does what?
protects vs. phagolysosomal components, probably basis for survival in macrophages
What are the components of the mycobacterium cell envelope? List them
A = cell memebrane
B = peptidoglycan
C =arabinogalactan
D = lipoarabinomannan–> like LPS but not LPS
E = proteins
F = mycolic acids
G = surface glycolipid
Who has an increase susceptibility of TB?
Substance abusers, AIDS patients
What is the fatality rate in untreated TB?
50%
What is the transmission of tuberculosis?
Airborne droplets
Where do the TB pathogens usually reside in human body to cause infection first?
Macrophages in alveoli
what do TB x-rays look like?
patches of white lesions
Talk out the procession of tuberculosis
If you have little or no hypersensitivity, are you tuberculin negative or positive?
Negative
If you are tuberculin negative, what happens?
progressive systemic disease and death
If you have little to no hypersensitivity to TB, what happens?
progressive systemic disease and death
If your patient has a delayed type hypersensitivity and cell mediated immunity to TB, are they tuberculin negative or positive?
Positive
If a patient is tuberculin positive, what happens?
Disease is contained, bacteria live but fail to replicated
What T cells response to TB in tuberculin positive patients?
Th1
what occurs in 25% of cases in tuberculin positive cases five years later ?
Ghon complex–> lung damage
What is the end result when a patient is tuberculin positive?
91% no disease
6% clinical TB
2% Pulmonary
1% both
3% progressive systemic disease and death
Is M.tuberculosis a single or multiple body site infectious disease? Name it or them
MULTIPLE BODY SITES
- lungs, bones, joints, liver, spleen, GI tract, brain
Where is M.tuberculosis always?
always within cells of reticuloendothelial system–> macrophages
What is the main defense of the lung again M. Tuberculosis ? Explain
pulmonary alveolar macrophages (PAM)
Ability to mount rapid, effective activated macrophage response determines outcome
M. tuberculosis can survive/grow where? Activated or nonactivated PAM?
NON-activated PAM
What do T cells do to layer of macrophages with M. tuberculosis?
T-cells forms around damaged tissue, this walls off lesion with thick fibrin coat
—-granuloma, specifically called tubercle
—-Calcification ==> lesions in chest X-rays
What causes lesions in chest X-ray ?
Calcification
Granuloma can also be called what?
tubercle
Granuloma can also be called what?
tubercle
what is the response in healthy adult exposed to low numbers of M.tuberculosis?
TH1 response and activated macrophages appear early enough to stop infection
—>no appreciable damage to lung
—>skin test positive, but no symptomatic TB
—>viable bacteria may remain with potential for future reactivation TB – this applies regardless of presence of primary disease
What are the symptoms of M.tuberculosis ?
—fever, coughing, bloody sputum
—Weight loss, loss of energy
—Progressive lung damage
—Bacteria may escape lungs ==> systemic disease
How do we diagnosis TB? even the not so effective ones
Stain of sputum —> acid fast bacteria
—> problem: not specific for TB
Culture
—-> problem: 1-2 months to grow
TB skintest: key to rapid easy surveillance
How does the TB skin test work?
ID injection of tuberculin–> purified protein derivative (PPD) which stimulates pre-primed CD4 -helper cells at injection site that leads to secretion of cytokines and delayed hypersensitivity reaction
how long do you have to wait after TB exposure?
about 4 weeks
What is the percentage of people that were positive skin test develop active TB?
3-5%
What is the percentage of people that were positive skin test develop active TB?
3-5%
What would cause a positive TB test if not exposed?
BCG vaccine
PPD skin test is considered what reaction?
delayed hypersensitivity
How does the PPD skin test work? more immunology explanation
-PPD injected and interacts with tissue macrophages or dendritic cells
-PPD is processed and the APC produce factors that attract lymphocytes
- The processed PPD is moved to cell surface and presented to PPD specific T cells at the injection sit
-Interaction of PPD T cell and PPD on APC cell surfaces causes chemotactic factors and gamma interferons
-Monocytes begain to migrate to injection site from the blood in 24-48 hours. This induration is the result of this late inflammatory reaction
- The IFN gamma activates the monocytes/macrophages to enhanced killing of M. tuberculosis
What activates the monocytes/macrophages to enhance killing of M.tuberculosis ?
IFN gamma
What is traditional therapy for TB?
combinations used (INH-rifampin)
streptomycin, isonicotinic acid hydrazide (isoniazid, INH) rifampin, ethionamide, pyrazinamide, ethambutol, PAS
When used medications singly instead of combo, what happens?
RESISTANCE
More specific: streptomycin, INH, ethionamide, and rifampin
What is treatment combo success rate for TB?
90%, even in AID patients!
What are the exceptions of the 90% treatment success rate?
MDR TB- multi drug resistant TB
XDR TB-extensively drug resistant TB
CDR TB-completely resistant to TB
What is the prevention for TB
Bacille calmette-guerin (BCG)
Bacille calmette-guerin (BCG) was made how?
M. bovis subcultured every 3 weeks for 13 years – became avirulent for calves
What country did not use BCG?
USA
How is BCG given? old and new
initially orally but now intradermally
What are the limits of BCG?
Initial deaths in children from contaminated vaccine
Different strains/vaccines–> 40 manufacturers
Adverse reactions–> localized to fatal disseminated BCG infection
Clinical trials show varied efficacy
COMPROMISES THE TB SKIN TEST
What are general details of Bartonella henelae (Bh)
Fastidious slow growing bacterium
Facultative intracellular
Gram (-) rod
Two forms in culture:
— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)
What is the morphology of Bh?
Gram negative rod
what are the forms in culture of Bh?
— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)
what are the forms in culture of Bh?
— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)
What are the two diseases caused by Bh?
Cat-scratch disease
Bacillary angiomatosis
What is cat scratch disease and what is bacteria caused by it?
Bh
Lymphadenopathy—> immunocompetent individuals
Cat scratch disease is found in what types of individuals ?
Immunocompetent
What is bacillary angiomatosis and what bacteria causes this?
Bh
Lesion of the skin or internal organs associated with systemic infection and characterized by proliferation of the vascular endothelium
In immunocompromised people
What type of individuals get bacillary angiomatosis
immunocompromised
what is the reservoir host for Bh?
feline
What is the vector for Bh?
Cat-flea
What are the virulence factors of Bh?
BadA-adhesin
Type IV secretion system (VirB)
Beps- effector proteins
What are the virulence factors of Bh?
BadA-adhesin
Type IV secretion system (VirB)
Beps- effector proteins
How does Bh cause angiogenesis?
Interaction with macrophages to produce proangiogenic factors (VEGF)—> BadA
Interaction with endothelial cells to inhibit apoptosis and to promote proliferation and table (capillary) formation (IL-8) and chemotaxis of macrophages (MCP-1)—>VirB and Beps
What is the type of secretion system in Bh?
type IV–> VirB
How do you diagnosis Bh?
Serology
PCR
How do you treat Bh?
Azithromycin or doxycycline for systemic infection
What is the prevention of Bh?
No vaccine
Limit exposure to cats for immunocompromised
What are the obligate intracellular bacteria ?
Rickettsia rickettsii –> RMSF
Ehrlichia chaffeensis–> ehrlichiosis
Chlamydia trachomatis
What does rickettsiae include?
Rickettsia, Coxiella, Ehrlichia, Anaplasma
What is the morphology of rickettsiae ?
Gram negative pleomorphic(all of bacteria make different size and shapes) rods
What is the vector of rickettsiae?
arthropod—> ticks
What is the reservoir for rickettsiae?
animal
What are the skin manifestation of bacterial zoonoses?
macule: small flat area with discoloration
papule: small, solid, raised skin lesion
erythema: redness or inflammation
petechiae: flush red or purple spots caused by minute hemorrhages
Nodule: small firm rounded mass or lesion
Rock mountain spotted fever is caused by what?
Rickettsia rickettsii
What is the reservoir or Rock mountain spotted fever ?
rodents, dogs, ticks
what is the vector of Rock mountain spotted fever
ticks
What is the presentation of Rock mountain spotted fever ?
Triad of fever, tick bite and rash (centripetal, maculopapular with petechiae)
Other symptoms: headache, confusion myalgia, vascular collapse (DIC, heart failure), renal failure
What is the diagnosis of Rock mountain spotted fever ?
Clinical triad
The importance of patient’s history
- possible tick bite
-outdoor activity
-travel to endemic areas
Lab: direct IFA or PCR, retrospective serology
What is the laboratory diagnosis of Rock mountain spotted fever ?
direct IFA or PCR
Retrospective serology
What is the treatment of Rock mountain spotted fever ?
Tetracyclines
What is the prevention of Rock mountain spotted fever ?
tick removal, DEET
What is similar to RMSF? what is the difference?
Ehrlichiosis but no rash
What is the reservoir of Ehrlichiosis ?
Deer–> deer mice
What is the vector of Ehrlichiosis ?
Amblyomma species (specific species of tick)
What is the diagnosis of Ehrlichiosis?
serology or blood smears stains with Giemsa
What is the treatment of Enrlichiosis
Tetracyclines
What are considered energy parasites?
Chlamydia
What is the morphology of chlamydia?
small pleomorphic, gram negative
What is unique about chlamydia ?
No peptidoglycan so no beta lactam antibiotics
What will not work on Chlamydia and why?
beta lactam antibiotics because chlamydia does not have peptidoglycan
Chlamydia has how many forms of life cycle? what are they?
Two
- Extracellular form: elementary body
-replicative form: reticular body
Explain the lifecycle of Chlamydia ?
What are the infections caused by Chlamydia trachoatis?
-Respiratory tract
- ocular —> conjunctivitis and trachoma
-genital tract—> nongonococcal urethritis, PID and lymphogranuloma venereum
What are the ocular infections caused by Chlamydia?
Conjunctivitis
Trachoma (Symptoms begin with mild itching and irritation of the eyes and eyelids. They may progress to blurred vision, eye pain, and even blindness)
What are the genital infections of Chlamydia?
nongonococcal urethritis
PID
lymphogranuloma venereum (know this this because it’s unique)
Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:
(A) After being stained with carbolfuchsin, M. tuberculosis resists decolorization with acid alcohol.
(B) Mycobacterium tuberculosis has a large amount of mycolic acid in its cell wall.
(C) Mycobacterium tuberculosis appears as a red rod in Gram- stained specimens.
(D) Mycobacterium tuberculosis appears as a red rod in acid-fast–
stained specimens.
c
Each of the following statements concerning chlamydiae is correct EXCEPT:
(A) Chlamydiae are strict intracellular parasites because they cannot synthesize sufficient adenosine triphosphate (ATP).
(B) Chlamydiae possess both DNA and RNA and are bounded by a cell wall.
(C) Chlamydia trachomatis has multiple serotypes that can cause different diseases.
(D) Most chlamydiae are transmitted by arthropods.
d
Each of the following statements concerning Rocky Mountain spotted fever is correct EXCEPT:
(A) The causative organism forms β-hemolytic colonies on blood agar.
(B) Headache, fever, and rash are characteristic features of the disease.
(C) The disease occurs primarily east of the Mississippi.
(D) The disease is caused by a Rickettsia.
a
Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:
(A) Some strains of M. tuberculosis isolated from patients exhibit multiple drug resistance (i.e., they are resistant to both isoniazid and rifampin).
(B) Mycobacterium tuberculosis contains a small amount of lipid in its cell wall and therefore stains poorly with the Gram stain.
(C) Mycobacterium tuberculosis grows slowly, often requiring 3 to 6 weeks before colonies appear.
(D) The antigen in the tuberculin skin test is a protein extracted from the organism.
b
