Microbiology Flashcards
Define “aerobe.”
Microorganism that uses an oxygen-dependent system to generate ATP
List 5 important examples of aerobes.
Nocardia, Neisseria Pseudomonas aeruginosa, Mycobacterium tuberculosis, Bordetella
“Nagging Pests Must Breathe”
Why are anaerobes susceptible to oxidative damage?
They lack catalase and/or superoxide dismutase.
List 4 important examples of anaerobes.
Clostridium, Bacteroides, Fusobacterium, Actinomyces
“anaerobes Can’t Breathe Fresh Air”
Define “facultative anaerobe.”
Use fermentation and other non-oxygen-dependent pathways to generate ATP, but are not killed by O2.
List 3 important categories of facultative anaerobes.
- Streptococci
- Staphyloccci
- Enteric gram positive bacteria
List the 3 obligate intracellular bugs.
Rickettsia, CHlamydia, COxiella
“Stay inside (cells) when it is Really CHilly and COld.”
List the 8 facultative intracellular bugs.
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
“Some Nasty Bugs May Live FacultativeLY”
List the 8 encapsulated bacteria.
Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus Influenza type B, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumonia, group B strep (+ S. pyogenes - hyaluronic acid capsule, B. anthracis - polypeptide capsule)
“Please SHINE my SKiS”
List the three encapsulated bacteria vaccines.
S. pneumoniae (PCV13 - conjugated, PPSV23 - not conjugated), H. influenzae type B (conjugated), N. meningitidis (conjugated)
What is the point of conjugated carrier proteins in vaccines containing polysaccharide capsule antigens?
A polysaccharide antigen alone cannot be presented to T cells. By conjugating a carrier protein, this promotes T-cell activation and subsequent class switching, enhancing immunogenicity.
List the 8 urease-positive organisms.
Proteus, Cryptococcus, H. pylori, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus
“Pee CHUNKSS”
List the 10 catalase-positive organisms.
Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staphylococci, Serratia, B. cepacia, H. pyloria
“Cats Need PLACESS to Belch their Hairballs”
Bacteria producing yellow pigment?
S. aureus
Bacteria producing yellow “sulfur” granules?
A. israelii
Bacteria producing red pigment?
Serratia marcescens
Bacteria producing blue-green pigment?
P. aeruginosa
List the 4 bugs producing in vivo biofilms.
S. epidermidis
Viridans streptococci (S. mutans, S. sanguinis)
P. aeruginosa
Nontypeable (unecapsulated) H. influenzae
List the 3 bugs with an IgA protease virulence factor.
S. pneumoniae, H. influenzae type B, Neisseria
SHiN
List the 4 bugs and associated exotoxins that inhibit protein synthesis.
- C. diphtheriae (diphtheria toxin)
- P. aeruginosa (exotoxin A)
- Shigella spp. (Shiga toxin)
- EHEC (Shiga-like toxin)
Which 2 bacteria produce a toxin that inactivates the 60S ribosome by removing adenine from rRNA?
Shigella spp. (Shiga toxin) and EHEC (Shiga-like toxin)
Which 2 bacteria produce a toxin that inactivates elongation factor (EF-2)?
C. diphtheriae (diphtheria toxin) and P. aeruginosa (exotoxin A)
List the 3 bugs and associated exotoxins that increase fluid secretion.
- ETEC (heat-labile toxin and heat-stable toxin)
- Bacillus anthracis (edema toxin)
- Vibrio cholerae (cholera toxin)
Compare the MOA of the toxins seen in ETEC, B. anthracis, and V. cholerae.
Heat-labile toxin (ETEC) and cholera toxin (V. cholerae) overactivate AC -> increased cAMP -> increased chloride secretion in the gut and H2O efflux.
Heat-stable toxin (ETEC) overactivate GC -> increased cGMP -> decreased resorption of NaCl and H2O in the gut
Edema toxin (B. anthracis) - mimics AC
“Labile in the Air - AC, Stable on the Ground - GC)
List the 1 bug and associated exotoxin that inhibit phagocytic ability.
- B. pertussis (pertussis toxin)
List the 2 bugs and associated exotoxins that inhibit release of NT.
- C. tetani (tetanospasmin)
2. C. botulinum (botulinum toxin)
What are AB toxins?
Two or three-component toxins - B enables binding and triggering uptake of the active A component; the A components are usually ADP ribosyltransferases.
List the 10 AB toxins.
- Diphtheria toxin
- Exotoxin A (P. aeruginosa)
- Shiga toxin
- Shiga-like toxin (EHEC)
- Heat-labile toxin (ETEC)
- Edema toxin (B. anthracis)
- Cholera toxin
- Pertussis toxin
- Tetanospasmin
- Botulinum toxin
List the 2 bugs and associated exotoxins that lyse cell membranes.
- Clostridium perfringens (alpha toxin)
2. Streptococcus pyogenes (streptolysin O)
List the 2 bugs and associated exotoxins that are superantigens causing shock. Describe the MOA.
- Staphylococcus aureus (TSST-1)
- Streptococcus pyogenes (exotoxin A)
Bind to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-gamma, and TNF-alpha (shock)
What are the 3 components of LPS?
- O antigen
- Core polysaccharide
- Lipid A (toxic component)
What are the three main effects of LPS? Discuss the pathogenesis.
- Macrophage activation (IL-1, IL-6 -> fever, TNF-alpha -> fever and hypotension, NO - hypotension)
- Complement activation (C5a -> neutrophil chemotaxis, C3a and C5a -> histamine release -> hypotension and edema)
- Tissue factor activation (coagulation cascade -> DIC)
List the # lactose fermenting bacteria.
Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia
“macConKEE’S agar)
Citrobacter and Serratia are weak fermenters
List the 1 single-stranded DNA virus (all other DNA viruses are double stranded).
Parvovirus
List the circular DNA viruses (all others are linear).
Papilloma, polyoma, and hepadnaviruses.
List the DNA virus familys.
- Herpesvirus
- Hepadnavirus
- Adenovirus
- Poxvirus
- Papillomavirus
- Polyomavirus
- Parvovirus
HHAPPPy
List the enveloped DNA viruses.
- Herpesvirus
2. Hepadnavirus
List the naked DNA viruses.
- Papillomavirus
- Polyomavirus
- Adenovirus
- Parvovirus
PAPP
List all of the naked viruses.
- Papillomavirus
- Polyomavirus
- Adenovirus
- Parvovirus
- Calcivirus
- Picornavirus
- Reovirus
- Hepevirus
“Give PAPP smear and CPR to a naked hippie (hepevirus)”
Generally, enveloped viruses acquire their envelopes from plasma membranes when they exit from a cell. What is the major exception and where does it acquire its envelope from?
Herpesviruses - from the nuclear membrae
All DNA viruses are double-stranded, except for ___.
Parvovirus (single-stranded)
All DNA viruses have linear genomes, except ___, ___, and ___.
Papillomavirus and polyomavirus (circular, supercoiled), hepadnavirus (circular, incomplete)
All DNA viruses are icosahedral, except ___.
Poxvirus (complex)
All DNA viruses replicate in the nucleus, except ___.
Poxvirus (carries its own DNA-dependent RNA polymerase)
Generally, where do DNA viruses replicate? RNA viruses?
DNA viruses replicate in the nucleus (except poxvirus, “pox is out of the box”)
RNA viruses replicate in the cytoplasm (except influenza virus and retrovirus)
All RNA viruses are single stranded, except for ___.
Reoviruses (double stranded)
List the positive single stranded RNA virus families.
- Retrovirus
- Togavirus
- Flavivirus
- Coronarvirus
- Hepevirus
- Calicivirus
- Picornavirus
“I went to a RETRO TOGA party, where I drank FLAVored CORONA and ate HIPPIE CALIFORNIA PICKLES.”
Which viruses require polymerases contained in the complete virion to be infectious?
Negative strand ssRNA and dsRNA viruses
List the negative single stranded viruses.
- Arenavirus
- Bunyavirus
- Parmyxovirus
- Orthomyxovirus
- Filvirus
- Rhabdovirus
“Always Bring Polymerase Or Fail Replication”
List the 4 segmented viruses.
- Bunyavirus
- Orthomyxovirus
- Arenavirus
- Reovirus
(All are RNA)
What are the 2 important Reoviruses?
- Rotavirus
2. Coltivurs
What are the Picornaviruses?
- Poliovirus
- Echovirus
- Rhinovirus
- Coxsackievirus
- HAV
“PERCH on a peak”
Which picornavirus is not an enterovirus?
Rhinovirus
List the circular RNA viruses.
Arenavirus
Bunyavirus
Hepatitis D virus
Where is HSV2 latent? ZVZ? CMV?
HSV2 - sacral ganglia
VZV - dorsal root or trigeminal ganglia
CMV - mononuclear cells
What is the largest DNA virus? The smallest DNA virus?
Poxvirus; Parvovirus
List the arboviruses.
- Coltivirus
- Yellow fever
- Dengue
- St. Louis encephalitis
- WNV
- Zika virus (Aedes mosquito)
- Western and Eastern equine encephalitis
- Chikungunya virus
- Bunyavirus
Discuss how herpesviruses are diagnosed.
Test of choice - PCR of skin lesions, CSF PCR for encephalitis
Other tests for skin/genital lesions: viral culture, Tzanck test
What is a Tzanck test?
Smear of an opened skin vesicle used to detect multinucleated giant cells (commonly seen in HSV1, HSV2, VZV)
What type of inclusion is seen in HSV1, HSV2, and VZV?
Intranuclear eosinophilic Cowdry type A inclusions
List the receptor used by the following viruses:
- EBV
- CMV
- Parvovirus
- Rhinovirus
- HIV
- Rabies virus
- EBV - CD21
- CMV - integrins
- P antigen (RBCs)
- ICAM-1
- HIV - CD4, CXCR4, CCR5
- Nicotinic AChR
What is the role of hemagglutinin and neuraminidase in influenza virus (and other orthomyxo and paramyxoviruses)?
HA - binds sialic acid, promotes viral ENTRY
NA - promotes virion RELEASE
What feature of HCV leads to variation in antigenic structure of its envelope proteins?
HCV lacks 3’ to 5’ exonuclease activity - thus, it has no proofreading ability; host antibody production lags behind production of new mutant strains
Which virus has a reverse transcriptase but is not a retrovirus?
HBV
Discuss HBV replication.
Upon entry into the nucleus, the HBV DNA polymerase completes the partial dsDNA. Host RNA polymerase transcribes mRNA from viral DNA to make viral proteins. The DNA polymerase then reverse transcribes viral RNA to DNA (genome of the progeny).
What HBV antigen indicates current infection?
HBsAg
What does anti-HBs indicate?
Immunity to HBV due to vaccination or recovery from infection
What does anti-HBc indicate?
If IgM, acute/recurrent infection with HBV.
If IgG, prior exposure or chronic infection
What may be the sole positive marker of HBV infection during the window period?
Anti-HBc
What does HBeAg indicate?
Active viral replication (high transmissibility, poorer prognosis)
What does anti-HBe indicate?
Low transmissibility
What does anti-HAV IgM indicate?
Acute hepatitis A
What does anti-HAV IgG indicate?
Prior HAV infection or prior vaccination protects against reinfection