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MMG Respiratory Bacterium


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What are the signs and symptoms of Streptococcal Disease?
-sore throat
-difficulty swallowing
*may progress to scarlet or rheumatic fever
What is the Etiological agent for Strep and how does it enter the body?
-Group A streptococi (S. pyogenes, pneumoniae, and faecalis)
-upper respiratory tract via respiratory droplets
How do you treat strep?
-penicillin or other antibiotics
What are the different types of hemolysis seen from the three types of strep infections?
-Alpha= S. pneumoniae
-Beta= S. pyogenes
-Gamma= S. faecalis
What is the suppurative form of strep?
-pus forming, strep throat
-scarlet fever
What is the M protein?
-pili/fimbrae-like structures
-used for attachment (has specificity)
-major virulence antigen (80 different types; superantigen)
-anti-phaocytic; important for suppurative form
*antibody agains M protein is protective against infection!
Describe Erythrogenic toxin.
-produces by a lysogenic bacteriophage (superantigen)
-responsible for scarlet fever rash
-"Dick Test"
-predisposes tissue to damage by other toxins such as endotoxins so one becomes more sensitive
What is the Dick Test?
-indicates exposure to Erythrogenic toxin
-detects circulating antibody to toxin
What are hemolysins?
-Streptolysin S and O
-responsible for strep throat
What does Streptolysin S do?
-oxygen stable hemolysin
-responsible for blood agar reaction
-toxic to tissue, leukocytes, red blood cells
What do Streptolysin O do?
-oxygen labile hemolysin
-binds cholesterol, cardiotoxic and other tissues
What is streptokinase used for?
-spreadin factor
-dissolves fibrin blood clots
What is impetigo?
-skin form of strep infection
What are "flesh eating" bacteria known as?
-necrotizing fasciitis
What is Scarlet fever?
-produces erythrogenic toxin (encoded by phage) that causes red rash, can be very severe
What is a sequela disease?
-a disease that is cuased by a preceding disease or inury in the same infividual
-a follow up disease
*Rheumatic fever and Acute Glomerulonephritis
Why is S. pyogenes such a huge problem in terms of sequela diseases?
-antigenic similarities to human tissues so if introduction occurs again, the body is also attacked!
Describe Rheumatic fever.
-M protein antibodies cause pharyngitis, joint inflammation, reddened skin, heart valve damage (cross-react with myosin protein in heart)
How do you treat Rheumatic fever?
-antibiotics (penicillin, erythromycin) if diagnosed early
Describe Acute Glomerulonephritis.
-from pharyngitis or skin infection
-blood in uring, edema, hypertension, severe pain
-S. pyogenes antigen-antibody complexes lodge in glomeruli of kidney
How do you treat Acute Gomerulonephritis?
-antibiotics liek penicillin and erythromycin
Describe Necrotizing fasciitis.
-extensive destruction of subcutaneous tissue
-due to massive immune (T cell) response to M protein and exotoxins
-treatable with antibiotics but can cause death in ~30% of cases due to rapid effects
What are the three types of tuberculosis?
-primary; initial case
-secondary; reestablished
-disseminated; tuberculosis involving many systems
What are the signs of initial TB?
-minor cough and mild fever
-difficulty breathing, chest pain, wheezing, and coughing up blood
What is the Etiological agent of TB?
-Mycobacterium tuberculosis
-Gram +, acid-fast bacillus
-slow growing (6W to colony)
-Cord factor
-mycolic acid in cell wall
What is special about mycolic acid in TB?
-protects cell allowing them to remain viable for long periods in aerosol drops
What is a cord factor in TB?
-protein attached to daughter cells in parallel alignment
-in cell wall
-required to cause disease
Describe pathogenesis of TB
-lodges in lungs
-surviveswithin un-activated alveolar macrophages
-elicits massive ummuve response and host cell damage
-forms aggregates of macrophages called tubercles
How do you diagnose TB?
-TB skin test identifies previous exposure to M. tuberculosis
-doesn't distinguish between active disease, chronic carriers, or those who have been vaccinated
How do you treat TB?
-nicotinamide derivative (Isoniazid) plus 3-4 other antibiotics daily for six months
How does isoniazid work?
-inhibits enzymes required for synthesis of mycolic acid
-growth factor analog
*M. tubercolulosis is highly mutable, leadin gto increases in antibiotic-resistant strains
What is pneumonia and what are the three types?
-inflammation of lungs with fluid-filled alveoli and bronchioles
-lobar, mycoplasmal, nosocomial
What are the signs of bacterial pneumonias?
-fever, chills, congestion, cough, chest, pain, and short, rapid breathing
What is the etiological agent for pneumonia?
What is its susceptibility?
-S. pneumoniae, Gr +
-Immunocompromised individuals, harmless normal flora for most people
What virulence factors does S. pneumoniae have?
-adhesins, capsule, pneumolysin (binds cholesterol and makes pores in cells)
What are some other etiological agents?
-Mycoplasma pneumoniae, K. pneumoniae, Haemophilus influenzae, S. aureus, Yersinia pestis, Chlamydia spp.
What are some systemic mycoses from fungus' that are involved in the respiratory system?
-Pneumocystis pneumonia (common fungal pneumonia of AIDS patients)
What is the most common environmental mold?
-Aspergillosis flavus
*primary and opportunistic pathogen
What are signs/symptoms of Aspergillosis infection?
-respiratroy distress
-allergic reaction
Describe Aspergillus flavus.
-inhalation of fungal microconidia into lungs
-fungus ball is non-invasive, encapsulated hyphal mass there
-found in soil and dexomposting organic matter and hay (Farmer's Lung)
How do you treat Aspergillosis?
-disseminated aspergillosis and ivasive pulmonary aspergillosis are both generally lethat
*anti-fungal treatment done but usually ineffective
What are signs and symptoms for Blastomycosis?
-flu like symptoms and chronic pneumonia
-systemic infections can produce painless lesions on the face and upper body or purulent lesions on various organs
Describe the Etiological agent of Blastomycosis.
-Blastomyces dermatitidis
-yeast like with braod based buds
-found in soil
-enters through inhalation of fungal spores in dust
-endemic to southeastern US and Canada
How do you treat Blastomycosis?
-usually progressive so treatment ALWAYS required
-amphotericin B is effective
What is Valley fever?
-caused from coccidioides immitis
What are the signs and symptoms of valley fever?
-resembles pneumonia or tuberculosis
-primary is asymptotic or resembles the flu (40%)
-produces coin lesion in lung
-progressive coccidioidomycosis can occur months or decades after primary infection! Meningitis
Describe Coccidioides immitis.
-dimorphic fungus
-hyphal form in soil
-arthroconidia are inhaled
What is the epidemiology of Valley fever and how is it diagnosed?
-endemic to SW US and Mexico; 10-50% are skin positive in endemic areas
-presence of spherules in clinical specimens
-Amphotericin B
What are the signs of Histoplasmosis?
-generally asymptomatic (95%) adn self-limiting
-some dry cough with blood tinged sputum and skin lesions (5%)
Describe the etiologlical agent of Histoplasmosis.
-Histoplasma capsulatum
-budding yeast
-enters by inhalation of conidia from soil contaminated with guano
-conidia engulfed by macro's and begin to grow intracellularly
What is the epidemiology of Histoplasmosis and how is it treated?
-endemic to eastern US but also found in parts of Africa and Central/South America
-Amphotericin B
-Defining opportunistic infection for AIDS with TX persisting for life
What are the signs for PCP?
-Pneumocystis Pneumonia
-difficulty breathing
-mild anemia
What is the etiological agent of PCP and how does it enter?
Pneumocystis jiroveci (previously P. carinii)
-inhalation of droplets conataining the fungus
What is the treatment of PCP?
-Timethoprim and sulfamehtaxazole (TMP-SMX)

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