Micro - Basic Bacteriology (Misc. Categories) Flashcards
Pg. 121-122 Sections include: Obligate aerobes Intracellular bugs Encapsulated bacteria Catalase-positive organisms Vaccines Urease-positive bugs Pigment-producing bugs Bacterial virulence factors
What is the defining characteristic of obligate aerobes?
Use an O2-dependent system to generate ATP
What are 3 examples of obligate aerobes?
(1) Nocardia (2) Pseudomonas (3) MycoBacterium tuberculosis; Think: “Nagging Pests Must Breathe”
What kind of metabolism does M. tuberculosis have as it pertains to oxygen use (or lack thereof)? What implication does this have for reactivation tuberculosis? FYI - What are 2 things that can cause M. tuberculosis reactivation?
Obligate aerobe; Reactivation of M. tuberculosis (e.g., after immune compromise or TNF-alpha inhibitor use) has a predilection for the apices of the lung, which have the highest PO2
What kind of metabolism does P. aeruginosa have as it pertains to oxygen use (or lack thereof)? In what contexts is P. aeruginosa seen?
Aerobe; Seen in burn wounds, complications of diabetes, nosocomial pneumonia, & pneumonias in cystic fibrosis patients
What are 3 examples of obligate anaerobes?
(1) Clostridium (2) Bacteroides (3) Actinomyces; Think: “anaerobes Can’t Breathe Air”
What is/are the defining characteristic(s) of obligate anaerobes with regard to function, identification/detection, and production?
They lack catalase and/or superoxide dismutase and are thus susceptible to oxidative damage; Generally foul smelling (short-chain fatty acids), are difficult to culture, & produce gas in tissue (CO2 and H2)
Where in the body are anaerobes normal flora? Where are they considered pathogenic?
GI tract; Elsewhere
Which antibiotics are ineffective against anaerobes, and why?
Aminoglycosides are ineffective against anaerobes because these antibiotics require O2 to enter into bacterial cell; Think: “AminO2glycosides require O2”
What are the obligate intracellular bugs, and why are they obligate intracellular?
(1) Rickettsia (2) Chlamydia; Think: “stay in side (cells) when it is Really Cold”; Can’t make own ATP
What are the 8 facultative intracellular bugs?
(1) Salmonella (2) Neisseria (3) Brucella (4) Mycobacterium (5) Listeria (6) Francisella (7) Legionella (8) Yersinia pestis; Think: “Some Nasty Bugs May Live FacultativeLY”
What are 7 examples of encapsulated bacteria?
(1) Streptococcus pneumoniae (2) Haemophilus influenaze type B (3) Neisseria meningitidis (4) Escherichia coli (5) Salmonella (6) Klebsiella pneumoniae (7) Group B Strep; Think: “SHiNE SKiS”
What 2 purposes can bacterial capsules serve with regards to immunity?
(1) Their capsule serves as an antiphagocytic virulence factor (2) Capsule + protein conjugate serve as an antigen in vacicnes
What kind of patients are particularly at risk for encapsulated bacterial infections, and why? What precautionary measures should be taken in this patient population?
Asplenics; Encapsulated bacteria are opsonized, and then cleared by the spleen, so Asplenics have decreased opsonizing ability & are at risk for severe infections; Give S. pneumoniae, H. influenzae, N. meningitidis vaccines.
What is the function of Catalase? What are 7 examples of catalase-positive organisms?
Catalase degrades H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase; (1) Pseudomonas (2) Listeria (3) Aspergillus (4) Candida (5) E. coli (6) S. aureus (7) Serratia; Think: “you need PLACESS for your CATs”
Which disease is related to infection with catalase-positive organisms, and why?
People with chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with these microbes because they degrade the limited H2O2
What is important to know about polysaccharide antigens with regard to vaccines?
For vaccines containing polysaccharide capsule antigens, a protein is conjugated to the polysaccharide antigen to promote T-cell activation and subsequent class switching. A polysaccharide antigen alone cannot be present to T cells; therefore, only IgM antibodies would be produced.
What is the main difference between Pneumovax and Prevnar?
Pnuemovax = polysaccharide vaccine with no conjugated protein; Prevnar = conjugated vaccine
Give 3 examples of conjugated vaccines.
(1) Prevnar (for S. pneumoniae) (2) H. influenzae type B (3) Meningococcal vaccines
What are the 8 urease-positive bugs?
(1) Crytococcus (2) H. pylori (3) Proteus (4) Ureaplasma (5) Nocardia (6) Klebsiella (7) S. epidermidis (8) S. saprophyticus; Think: “CHunk norrise hates PUNKSS”
Which bacteria are associated with yellow “sulfur” granules versus yellow pigment?
Actinomyces israelii - yellow “sulfur” granules which are composed of filaments of bacteria; S. aureus - yellow pigment; Think: “Israel has yellow sand” & “ aureus (Latin) = gold”
Which bacteria is associated with a blue-green pigment?
Pseudomonas aeruginosa; Think: “Aerugula is green”
Which bacteria is associated with a red pigment?
Serratia marcescens; Think: “RED MARaschino cherries”
What is the general purpose of bacterial virulence factors? What are 3 examples of such factors?
They promote evasion of host immune response; (1) Protein A (2) IgA Protease (3) M Protein
What is the mechanism of Protein A, and what is the resulting outcome? Which bacteria expresses Protein A?
Binds Fc region of Ig; Prevents opsonization and phagocytosis; Expressed by S. aureus
What is the mechanism of IgA protease? Which bacteria secrete it, and why?
Enzyme that cleaves IgA; Secreted by S. pneumoniae, H. influenzae type B, and Neisseria (SHiN) in order to colonize respiratory mucosa
What function does M protein serve? Which bacteria expresses it?
Helps prevent phagocytosis; Expressed by group A steptococci
