-
What bacterial enzyme does the positive indole test detect the presence of
tryptophanase
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Catalase positive, Coagulase positive
Staphylococcus aureus
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Catalase positive, Coagulase negative
Staphylococcus epidermidis
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If catalase negative, what test do you do next
Hemolysis on blood agar plate
-
What are the two possible bacterial genera that are Gram positive, Catalase negative
Streptococcus and enterococcus
-
Catalase negative, alpha hemolysis, optochin sensitive, positive bile solubility test
Streptococcus pneumoniae
-
Catalase negative, alpha hemolysis, all other tests negative
Viridans groupd streptococcus
-
Catalase negative, Beta hemolysis, Bacitracin sensitive
Group A Streptococcus pyrogenes
-
Catalase negative, +CAMP test
Group B streptococcus agalactiae
-
Catalase negative, gamma hemolysis, Positive Bile esculin test, + Growth in 6.5% NaCl
Group D enterococcus
-
Catalase negative, gamma hemolysis, Positive bile esculin test, NO growth in 6.5% NaCl
Group D streptococcus (Non-enterococcus)
-
After bacteria has been shown to be Gram Negative, what is the next test to use?
Oxidase test
-
Gram negative, Oxidase positive
Pseudomonas aeuruginosa
-
Oxidase negative, grow on Mac Conkey agar-->turns media red, indole positive
Escherichia Coli
-
Oxidase negative, grown on Mac Conkey agar-->turns media red, indole negative, urea positive
Kiebsella pneumoniae
-
Oxidase negative, grow on Mac Conkey agar-->turns media red, indole negative, urease negative
Enterobacter aerogenes
-
3 organisms that are oxidase negative, grown on Mac Conkey again-->turn media red
Escherichia Coli, Kiebsella pneumoniae, Enterobacter aerogenes
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Oxidase negative, grown on Mac Conkey agar--> no color change, Black color for H2S production, Positive Indole test
Proteus vulgaris
-
Oxidase negative, grown on Mac Conkey agar--> no color change, Black color for H2S production, Negative Indole test
Proteus Mirabeles
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Oxidase negative, grown on Mac Conkey agar--> no color change, No Black color because no H2S production, Positive citrate test
Serratia Marcescens
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What two bacterium can transition between a metabolicaaly active and inactive form?
Bacillus and Clostridium
- What is the Vegetative form of Clostridium and Bacillus?
- metabollically active
-
What is the dormant form of Clostridium and Bacillus?
metabolically inactive
-
What is the process of transition from vegetative to spore?
Sporulation
-
What is the process of transition from spore to vegetative?
Germination
-
What compound binds the high concentration of Ca in a Bacillus or Clostridium spore?
dipicolinic acid
-
What type of reistance do spores exhibit?
heat resistant, radiation resistant, resist starvation for hundreds of years and still germinate
-
What are Petechiae, splinter hemorrhages and Osler nodes symptoms of?
infectious endocarditis
-
What are the criteria for diagnosing infective endocarditis?
new murmur, positive Echocardiogram, Positive blood culture
-
Most common cause of acute, native valve community acquired infectious endocarditis
Staphylococcus aureus
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Most common cause of subacute, native valve community acquired infectious endocarditis
Streptococci viridans
-
Most common cause of infectious endocarditis in IV drug users
Staphylococcus aureus
-
Most common cause of prosthetic valve acquired infectious endocarditis
S. epidermidis
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Why is S. epidermidis good at colonizinf articifical surface (prosthetic valve, catheters, etc)?
Biolfim (slime layer), polysaccharide matrix protects them from defense mechanisms that would normally eliminate them
-
What are opportunistic pathogens?
patheogens that are normally part of the natural flora, can cause infection when immunocompromised or when they get somewhere they aren't supposed to be
-
What are strict pathogens?
microbes with relatively potent or multiple virulense factors, almost always cause disease
-
What is the function of Protein A and where do you find it?
On bacteria, binds to antibody, prevents the antibody from binding to the cell and completing phagocytosis
-
What are the 3 pathways of complement activation?
Alternative pathway, Lecin-mediated, Classical Pathway
-
What is the function of Properdin
Protein in the system that stabilizes the C3bBb membrane convertase complex
-
What inactivates membrane bound C3b?
Factor H and I, convert C3b to iC3b
-
What symptoms would you have if you had deficiency in Factor I?
cant inhibit C3b from forming, you'd run out of it, Prone to infection of the upper respiratory, urinary systems, ear
-
What protects the self's own cells from immune system?
DAF and MCP inactivated C3bBb (membrane convertase) quickly
-
What are the consequences of DAF or MCP deficiency?
Paroxysmal noctrunal hemoglobinuria (self lyses own blood cells)
-
What are the consequences of C1INH deficiency?
Hereditary Angioneurotic Edema, classical pathway of complement is overactive, produce large amountf of C2a, vasoactive peptide and bradykinin
-
What are the consequences of C3 deficiency?
susceptibiltiy to encapsulated bacteria
-
What are the consequences of C5-C9 deficiency?
can't form MAC's susceptibility to Neisseria
-
What are the consequences of C1,2,4 deficiency?
immune complex disease
-
What Gram Positive Cocci are strrictly anaerobic?
Peptostreptococcus
-
What is the way to classify streptococcus based on serologic data?
Lancefield groups A-->W
-
What are the types of hemolytic patterns you can get on blood agar Hemolysis test?
Alpha, Beta, Gamma
-
What does alpha hemolysis indicate
partial hemolysis, green on agar plate
-
What does Beta hemolysis indicate
total hemolysis, clear on agar plate
-
What is the serologic group and hemolysis group for S. pneumoniae
None, alpha hemolysis
-
How does S. pneumoniae usually cluster?
diplococci
-
How does S. pneumoniae colonize the oropharynx?
surface adhesion proteins
-
What does Gamma hemolysis indicate
No hemolysis
-
What is the main virulence factor for Strep pneumoniae that is responsible for the ability to avoid phagocytosis?
Polysaccharide capsule
-
How does pneumolysin in S. pneumoniae causes complement activation?
lyses ciliated epithelial cells and activates complement via the classical pathway producing C3a and C5a, teichoic and peptidoglycan fragments activate complement via alternative pathway
-
What soluble substances do macrophages secrete that promote further inflammation?
IL1 and TNF alpha
-
How does Strep pneumoniae defend against phagocytosis?
Polysaccharide capsule, Pneumolysin inhibits phagocytic oxidative burst, phosphocholine binds to recptors on leukocytes, platelets and ECs allowing bacteria to enter cells and bloodstream
-
How does the adaptive immune system override the resistance to phagocytosis of bacterium's polysaccharide capsule?
antibodies directed at capsular polysaccharide
-
Why does Pneumonia produce Low grade fever in older people
They do not have the high functioning immune system, decreased number of cytokines, lower immune response
-
What are the age related changes of Pneumonia in elderly?
Decreased mucociliary clearance, increased colonization of oropharynx with pathogen, proliferation of bacteria in gastric contents (less stomach acid), increased aspiration
-
What is the CURB-65 Criteria for prognosis in Pneumonia?
Confusion, Urea (BUN>20 mg/dL), Respiratory rate (>30 breaths/min), Blood pressure (systolic < 90, diastolic < 60), Age >65
-
What is the most cause of atypical community acquired pneumonia?
Mycoplasma pneumoniae
-
What is the mechanism that antibodies overcome the effects of S.pneumoiae capsule?
antibody has Fc portion that is usually coated on the outside, macrophages have receptors for Fc, complement mediated killing
-
Where does Pneumococcal pneumonia accumulate?
alveolar spaces, often localized in the lower lobe
-
What are the symptoms of pneumococcal pneumonia?
fever (102-103F), coughing, production of blood tinged sputum, chest pain
-
What is common treatment for S. pneumoniae infection
Lovofloxacin (FQN), broad spectrum, orally, long half life allows daily dosing, little resistance (1.1%)
-
What is common combination treatment for S. pneumoniae infection
B-lactam (Cefpodoxime, Cefuroxime, Ceftriaxone) + macrolide, broad spectrum, oral or IV, poor bioavailability
-
Which B-lactam has problems with discordant therapy?
Cefuroxime
-
What macrolide is used to treat S. pnuemoniae?
Azithromycin, Clarithromycin, broad spectrum, rapid absorption but poor bioavailability, hepatic excretion, side effect= QT prolongation
-
What is the most common cause of nosocomial pneumonia?
Gram negative rods (P. aeruginosa, E. coli, H. influenzae)
-
What is a double sickening pattern associated with upper respiratory disease usually indicative of?
sinusitis
-
What is the typical symptoms of upper respiratory infection?
headache, shore throat, rhinorrhea
-
What is the typical symptoms of lower respiratory infection?
persistent cough, purulent sputum, shortness of breath
-
What kind of cough is associated with atypical vs. acute pneumonia?
non-productive for atypical, productive for acute
-
What timeline is associated with atypical vs. acute pneumonia?
atypical is insidious onset (over a week) acute pneumonia is rapid onset (2-3 days)
-
What causative agent of atypical pneumonia produces a high cold agglutinin titer?
Mycoplasma pneumoniae
-
What is the most common cause of bacterial phayrngitis?
Streptococcal
-
What is the most common cause of pharyngitis, viral or bacterial?
viral
-
What is the serologic (Lancefield) group and type of hemolysis exhibited by Streptococcus pyogenes?
A, Beta hemolysis
-
Group A streptococcus (GAS) has what major type protein on its surface?
M protein, two polypeptide chains complexed in alpha helix, anchored to membrane and extend through cell wall
-
What are the main virulense factors for S. pyogenes?
Hyaluronic acid capsule (blocks phagocytosis), M protein (inhibits complement C3b), C5a peptidase (inactivated complement C5a), adhesins, streptolysins, streptokinases, DNAases
-
What is the function of DNAases as virulence factors?
depolymerizae free DNA in pus, reduce viscosity & facilitate spread of bacteria
-
What is the function of Streptolysins S & O as virulence factors?
lyse leukocytes, erythrocytes, and platels (streptolysin S= B hemolysis)
-
What is the function of Streptokinases A & B as virulence factors?
degrade blood clots and fibrin deposites--facilitates spread of bacterium
-
What is responsible for the progression of S. pyrogenes to Scarlet Fever?
Pyrogenic Exotoxins (SpeA, SpeB, SpeC, SpeF), superantigens that stimulate macrophages and T helper cells
-
What heart condition can result from Rheumatic Fever?
Endocarditis (vegetations), myocarditis, pericarditis= PANCARDITIS
-
What is Molecular Mimicry and what disease is an example of it?
Host and invading microorganism share antigenic determinant, ex: Rheumatic Fever
-
What tests are most useful in confirming Rheumatic heart disease?
ASO (abs against streptolysin O), Anti-DNAse (abs agains streptococcal DNAse), Anti hyaluornidase (abs to hyaluronidase)
-
What are the virulence factors of B. pertussis
Adhesins, pertussis toxin, tracheal cytotoxin
-
What is a toxoid?
detoxififed toxin
-
What are the 3 stages of infection with Bordatella Pertussis
Incubation: 7-10 d, Catarrhal stage: 1-2 weeks, Paroxysmal stage 2-3 weeks, Convalescence stage: 3-4 weeks
-
What is the major virulence factor for C. diptheriae
Diphtheria toxin, A-B exotoxin actively excreted by bacterium stops protein synthesis
-
What are the symptoms of C. Diptheriae infection
Incubation: 2-4 days, sudden onset of malaise, low grade fever, exudative pharyngitis, sore throat, thick pseudomembrane, can progress to myocarditis and neuropathy
-
What are icosahedral capsids?
nearly spherical with 20 faces, 12 symmetrical pentamers
-
What are icosadeltahedral capsids
larger, more complex version of icosahedral capsids, 12 pentamers + hexamer subunits (soccerball)
-
What are helical capsids
cylindrical appearance, usually RNA genomes if helical virus infects human
-
What are the capsid properties of non-enveloped viruses?
very tough capsid, disease they cause do not require direct contact for transmission, virus can survive outside of host, harder to inactivate
-
What is the structure of viral envelope?
phospholipids, proteins and glycoproteins, membranous (lipid bilayer) derived from host cell membrane but modified by virus
-
What is the purpose of Glycoproteins in viral envelopes?
extend like spikes, serve as viral attachment proteins (VAPs), bind to receptor on surface of host cell
-
What is the transmission of enveloped viruses?
Not easily transmitted via fecal oral, fomites, air, usually transmitted in secreted body fluids or blood-blood transfer
-
Wht are the steps of viral infection?
attachment, penetration, uncoating, macromolecular synthesis, assembly, release
-
What is a host range?
range of species a virus can infect
-
What is tropism?
range of tissue types a virus can infect
-
How do most non-enveloped viruses penetrate host cell?
Endocytosis (viropexis= 3D conformational change of capsid, is less common)
-
How do most enveloped viruses penetrate host cell?
Fusion at cell surface (Fusion with endosome membrane= entire virion brought into cell viral envelope fuses with endosome)
-
Where does replication for all DNA viruses occur?
nucleus (exception= Pox virus)
-
Where does replication for all RNA viruses occur
cytoplasm (exception= retrovirus and orthomyxovirus)
-
Does DNA virus use its own DNA-dependent RNA polymerase to synthesize viral mRNAs?
No, it uses host cells, enzyme doesnt know the different between host cell and viral DNA
-
Does DNA virus use its own DNA binding proteins to synthesize viral mRNAs?
simple DNA viruses rely on host cell, complicated DNA viruses encode theis own DNA bps
-
What are the requirements for DNA replication of DNA viruses
Nuclear factor (host cell or virus provides), DNA-dependent DNA polymerase (host cell or virus provide), Primer (virus provides)
-
What does the RNA virus need early on for copying RNA?
RNA dependent RNA polymerase, virus must carry enzymes in virion or code for their production shortly after entry
-
How do (+) sense strand ss-RNA viruses replicate?
viral genome binds to host cell ribosomes and directs production of viral proteins, codes for RNA dependent RNA polymerase first, makes (-) sense strand to be template for multiple (+) strands
-
How do (-) sense strand ss-RNA viruses replicate?
bring RNA dependent RNA polymerase with them, makes (+) strand mRNAs to make protein using host cell ribosomes, makes multiple (-) strands with RNAdepRNApoly
-
How are nonenveloped viruses released from host cell?
lysis
-
How are enveloped viruses released from host cell?
lysis, budding or exocytosis
-
What is the most likely causative agent of Croup?
Parainfluenza viruses
-
What is the most likely causative agent of common cold?
Rhinovirus
-
What is the most likely causative agent of viral conjunctivitis?
Adenovirus (types 3 & 7)
-
What are the glycoproteins on the envelope of parainfluenza virus?
F (fusion) protien, and HN (hemagglutinin nuramidase) protein
-
Why does parainfluenza virus cause seal bark cough?
rapid replication results in giant cells and extensive cell lysis, inflammation of the airway and edema
-
What does tachypnea and wheezing indicate, upper or lower respiratory infection?
lower respiratory
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