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Block 6 - Week 2
Viruses and Bacteria
111
Biology
Graduate
08/14/2009

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Term
The chronic phase of hepatitis is responsible for most morbidity and mortality, can cause fibrosis and cirrhosis, with an increased risk for hepatocellular carcinoma. Which hep viruses have a chronic phase?
Definition
B, C, D, G, all enveloped
Term
Name the virus with the following features - released by exocytosis, shedding 10 days prior to symptoms, enters blood via GI, Fever, fatigue, nausea, loss of appetite and abdominal pain, self-limited, jaundice.
Definition
Hep a
Term
T or f: The hep a vaccine is an inactivated whole virus.
Definition
T
Term
In diagnosing HAV the IgM is positive for ________ months and the IgG is positive for ________.
Definition
4-6, decades
Term
How is HEV different from HAV?
Definition
Higher mortality, affects more women, no vaccine
Term
Which virus causes 90% of gastroenteritis in US?
Definition
Norwalk, +ssRNA; rotavirus also causes GE
Term
How are rotavirus and Norwalk different from each other since they both cause diarrhea?
Definition
Rota is a child disease passed person-2-person via fecal oral; Norwalk is adult passed fecal via food
Term
The the live pentavalent human-bovine virus reassortment rotavirus vaccine prevents what disease?
Definition
Gastroenteritis
Term
Which virus has these features - dsRNA, non-enveloped, 10-12 RNAs, double layered capsid, highly infectious and causes infantile diarrhea?
Definition
Reoviruses, rotavirus
Term
What is the research test for HAV?
Definition
Virus in feces by electron microscopy, PCR
Term
Which hep virus takes the longest to move out of the incubation period?
Definition
Hep b, with a range of 45-160 days; although most start at 15 days, hep c is second place
Term
What is the difference between pre-icteric and icteric phase of acute infection of hep virus?
Definition
Pre = prodrome symptoms of malaise, fatigue, fever, weight loss; icteric - jaundice with elevated bilirubin, decrease in clotting factors, rise in ALT>AST
Term
Which virus has these features - circular, partly dsDNA, has surface/core/preprotein antigens, heat stable, parenteral transmission by prevalence, exocytosis of virions.
Definition
Hep b
Term
If a person only has a mild acute hep b infection what is likely to occur in regards to their hep b status?
Definition
Likely become chronically infected
Term
The phases of chronic HPV include a replicative and non-replicative phase, but what is significant about the HBeAg/Ab as the phases progress?
Definition
The Ag becomes negative and the Ab becomes positive due to viral clearance
Term
What is the Hep B vaccination consist of?
Definition
3 shots of HBsAg
Term
What virus has these features - ssRNA circular, needs HBV for life cycle, parenteral (mostly drug), additive to inflammatory response, increase fulminant hepatitis, detected via Ag/Ab, no vaccine.
Definition
Hep d
Term
Name the virus with these features - +ssRNA, parenteral, majority of infections are asymptomatic, high rate of chronic infections, no vaccination.
Definition
Hep c
Term
What is the difference in Hep C Ab serology in acute and chronic infection?
Definition
Acute- Ab negative; Chronic - Ab positive
Term
Name the virus with these features - 30% homology to HCV, flavivirus, parenteral, high rate with HCV infection, does not cause hepatitis, protective against HIV while replicating in CD4 cells.
Definition
Hep g
Term
The influenza antivirals are called what and what is their method of delivery?
Definition
Oral - Amantidine, rimantidine; inhaled - zanamivir, oral - oseltamivir
Term
What is the mechanism for influenza a only antivirals and why do they only work for flu A?
Definition
they inhibit the M2 protein from acidifying endosomes and allowing viruses to uncoat; other flu viruses don’t use M2
Term
What is the mechanism for the influenza A/B antivirals?
Definition
both drugs are structural analogs of neuraminic acid. Inhibition of the viral neuraminidase of influenza A and B prevents the release of viral particles from infected cells, thus interfering with the spread of viral infection
Term
Define ribavirin’s mechanism of action and bioavailability.
Definition
Ribavirin is broad spectrum antiviral that is a guanosine analogue and thus interrupts viral mRNA formation and protein synthesis. It is available oral or IV and in all tissues except CNS
Term
The following drugs are good IV antivirals, identify their good oral counterparts - acyclovir, penciclovir, ganciclovir.
Definition
Val, fam, valgan
Term
What is the mechanism of action of acyclovir and at what stage is resistance developing?
Definition
Acyclovir becomes phosphor’d 3 times and enters a viral dna strand since it is a deoxguanosine analogue causing chain termination and the bad mRNAs inhibit viral DNA polymerases; resistance is developing through mutated thymidine kinase
Term
What two drugs are used for suppressive therapy for HSV outbreaks and shingles?
Definition
Valacyclovir, famciclovir
Term
What drug is a topical treatment for herpes labialis?
Definition
Penciclovir
Term
Which drug is used for the prophylaxis and treatment of CMV with toxicities related to bone marrow suppression?
Definition
Val/Ganciclovir
Term
Foscarnet is an IV drug that is used for resistant HSV and CMV strains, but what is its mechanism of action?
Definition
It is an inorganic phosphate analogue that binds to dna polymerases so that they cannot cleave pyrophosphates
Term
Trifluridiine, fomivirsen, cidofovir are antivirals that treat what disease caused by CMV?
Definition
Retinitis
Term
IFN-a, Lamivudine, telbivudine, adefovir, entacavir are all Hep B drugs that work through what mechanism?
Definition
They are nucleoside analogues that inhibit DNA polymerases and reverse transcriptases; lamivudine is used first, and the others are used against resistant strains
Term
T or F: Ribavirin is FDA approved for RNA infections like measeles and hantavirus; Cidofir is FDA approved for DNA infections like papovavirus and variola.
Definition
False, neither is approved, but they are still used
Term
Imiquimod and Podofilox are both used for what virus and disease?
Definition
Papillomavirus and anogenital and common warts
Term
Name the virulence factor with these features (Gm-)- toxins are directly translocated from the cytoplasm of the bacterial cell to the cytoplasm of the target mammalian cell like a needle, and are not subject to antibody-mediated neutralization.
Definition
Type 3
Term
Name the virulence factor with these features (Gm-)- the polypeptide chains that comprise the toxin are secreted across the cytoplasmic and then outer membranes in separate steps to have the toxin enter via endosomes.
Definition
Type 2
Term
What are the two functions of pili?
Definition
Sex pili, and adhesive functions
Term
____________ ________ are extracellular, usually consist of polysaccharides, and frequently function to inhibit phagocytosis. Capsular polysaccharides are often important components of vaccines against bacterial pathogens.
Definition
Bacterial capsules that can be Gm+/-
Term
_________ ___________ are metabolically inert and are resistant to environmental insults and can survive desiccation, freezing, radiation, etc.
Definition
bacterial spores
Term
What is the difference between the envelope of Gram - and + bacteria?
Definition
Gm+ has a thick cell wall on the outside and has covalently attached teichoic acids, Gm- has thin cell wall and an outer lipid bilayer
Term
What are the 3 major targets for antibiotics?
Definition
Cell wall, supercoiling enzymes, and ribosomes
Term
What type of antibiotics inhibit cross-linking of the peptidoglycan cell wall structure of bacteria?
Definition
Beta-lactams
Term
The LPS or lipopolysaccharide proteins on the outer leaflet of the outer lipid bilyer of Gm- bacteria is known as _________ that can cause septic shock.
Definition
Endotoxin
Term
Which of these molecules are PAMPs - Lipid A, TA, LTA, CW?
Definition
All
Term
What is the difference between horizontal and vertical gene transfers?
Definition
Horizontal is DNA transfer from one bacteria to another, vertical is mother to daughter cell
Term
T or F: pathogenicity islands are DNA acquired by bacteria via horizontal gene transfer.
Definition
True
Term
In bacteria what does competence refer to?
Definition
The ability to take up DNA, either naturally thru molecular mechanisms on the surface of the membrane or a bacteria’s membrane can be destabilized to allow it to happen, either way can allow for homologous recombination
Term
T or F: At a low frequency during lytic growth, bacteriophage can package large segments of the host cell chromosome instead of phage DNA. Subsequent infection delivers the DNA to a new bacterial cell.
Definition
True, it is called gene transduction
Term
What is the difference between the lytic and lysogenic cycle in temperate bacteriophages?
Definition
Lytic is the normal viral reproduction cycle, but lysogenic is when the viral dna is incorporated into the bacterial DNA and then daughter generations have those genes.
Term
What is the bacterial element with these features - Extrachromosomal elements capable of autonomous replication, circular, The rate of the initiation of DNA replication is subject to self control, contain loci that encode sex pili and proteins required for DNA transfer from donor to recipient cells.
Definition
Plasmid
Term
______________ are mobile genetic elements that are able to move from one genome to another and are completely dependent on the host replicon for replication.
Definition
transposons
Term
Which of the following are pathways for antibiotics resistance development - enzymatic inactivation/modification, active efflux, decreased permeability, mutated target gene.
Definition
All of them.
Term
What is superinfection?
Definition
Where the destruction of one microbe allows another to flourish
Term
T or F: a drug may be bactericidal against one bacteria and bacterstatic against another.
Definition
True
Term
T or F: all strains of s. aureus are pathogenic.
Definition
True
Term
Describe the morphology and metabolism of staph aureus and the two biochem tests that it return a positive result.
Definition
Gram positive, yellow round clusters, anaerobe that ferments glucose, both catalase and coagulase positive
Term
What is the hallmark of staph infection?
Definition
The abcess
Term
What are the common sites of colonization of s. aureus and how can it be spread?
Definition
Nasopharynx, skin, perineal area; contact with skin, fomites, aerosols
Term
Explain why each of the structures of s. aureus are virulence factors - capsule, peptidoglycan, teichoic acid, protein A, cytoplasmic membrane.
Definition
Inhibits chemotaxis and phago and facilitates adherence to synthetic material, endotoxin that stims pyrogens and complement, mediates attachment to mucosal surfaces and creates immune response, binds Fc receptor of IgG preventing clearance.
Term
Why is it that the following enzymes are considered virulence determinants of staph a - penicillinase, hyaluronidase, catalse, coagulase, fibrinolysin?
Definition
They promote bacterial spread or destroy antibiotic effectiveness
Term
S. aureus can cause which of the following diseases - cutaneous, endocarditis, bacteremia, pneumonia, septic arthritis, osteomyelitis, vascular device infection.
Definition
All
Term
Staph Scalded Skin Syndrome and localized bullous impetigo are cutaneous disease caused by what staph a. exotoxin?
Definition
Exfoliative exotoxin A and B which targets desmoglein-1 which hold together keratinocytes, resolved by antibody development
Term
T or F: staph food poisoning is the result of a heat stable, digestion resistant, exotoxin that is preformed and not from a direct effect of the bacteria.
Definition
False, enterotoxin. Foods include ham, pork, potato salad, cream pies, ice cream
Term
Toxic shock syndrome is caused by s. aureus and s. pyogenes due to the TSST-1 toxin, what are the 4 key features of TSS?
Definition
Fever (38.9C), hypotension, diffuse rash and desquamation
Term
TSST-1 is an exotoxin and a superantigen, what is a superantigen?
Definition
A toxin that causes stimulation of up to 20% of t-cells via the TCR without the need of an antigen in the MHC
Term
S. epidermis is a coagulase negative, less virulent version of S. aureus, what types of infections does it cause?
Definition
Infectects artificial heart valves, prosthetic joints, catheders, other prosthetic devices.
Term
Penicillin binding protein PBP produces the peptidogylcan cross-linking in bacterial cell walls, how is MRSA different?
Definition
It has a mec-A gene that produces a PBP-2a that only weakly binds methicillin.
Term
T or F: CA-MRSA and nosocomial MRSA are the same bacteria.
Definition
False; CA-MRSA is different and it is PVL-gene positive and TMP-SMX sensitive
Term
What is the mechanism of action for MRSA drugs daptomycin and linezolid?
Definition
Daptomycin depolarizes the bacteria via a K+ channel insertion, Linezolid inhibits protein synthesis
Term
90% of strep diseases are due to which group?
Definition
Group A Strep Pyogenes
Term
Identify the bacteria with these features - Gm+, non-spore forming, non-motile, fastidious anaerobe, encapsulated, complete hemolysis on blood agar, catalase negative.
Definition
Strep groups A and B
Term
Identify the bacteria with these features - Gm+, non-spore forming, non-motile, fastidious anaerobe, non-capsulated, partial or incomplete hemolysis on blood agar, catalase negative.
Definition
Strep viridans and enterococci
Term
T or F: Strep pyogenes can either cause asymptomatic colonization or pharyngitis/skin infection which are all self-clearing.
Definition
True
Term
Which of the following are true about the surface virulence factors of S. Pyogenes - non-immunogenic capsule of hyaluronic acid, protein f attaches to fibronectin in tissues, M protein exerts anti-phagocytic activity in the absence of type-specific antibody and stimulates type-specific protective immunity.
Definition
All of them
Term
What is the difference between streptolysin O and S, the secreted virulence factors from strep pyo?
Definition
O is heat and oxygen labile and lyses PMNs and hemolytic that is antigenic, S is oxygen stabile and lyses PMNs and hemolytic but not antigenic
Term
Which of the following enzymes are secreted virulence factors from Strep pyo - DNases which hydrolyze DNA in pus, streptokinase which dissolve clots via plasmin, or C5 peptidase which cleaves complement.
Definition
All of them are secreted
Term
What are the 3 groups of exotoxins from strep pyo that are superantigens responsible for the rash in scarlet fever and are responsible for septic shock?
Definition
Spe A and B which are phage encoded, and C which is chromosomal
Term
Strep throat + rash = ?
Definition
scarlet fever
Term
T or F: group a strep pharyngitis is mainly in children but complications can result in spread to sinus, ear, lungs, blood, or cause glomerular nephritis.
Definition
True
Term
Differentiate the depth of skin involvement in the following strep pyo skin infections - impetigo (pustules in exposed areas on kids), erysipelas (well-demarcated), cellulitis (indistinct demarcation), and necrotizing fasciitis.
Definition
Epidermis, epi and dermis, epi/dermis/subcu, epi/dermis/subcu
Term
What is the diagnosis and treatment choices for group a strep?
Definition
Diagnosis with culture and anti-strepolysin O with antigen detection that is highly sensitive; treatment is penicillin
Term
T or F: strep a pharyngitis can cause acute rheumatic fever, and both throat and skin infections can result in acute glomerular nephritis.
Definition
True
Term
Why is it important to screen pregnancies for Group B strep?
Definition
It is a common cause of newborn disease and via genitourinary carriage which can cause sepsis, pneumonia, or meningitis
Term
Which bacteria is notoriously antibiotic resistant, commonly infects in hospitals via contact or antimicrobial treatment or catheter placement causing UTI/septicemia/endocarditis, but is part of normal bowel flora?
Definition
Enterococci
Term
Both sulfonamides (PABA analogue) and trimethoprim (competitive DHFR inhib) block folate synthesis, but which is bacteriostatic and which is bactericidal?
Definition
Sulfonamides are bacteriostatic, and trimethoprim kills bacs
Term
T or F: sulfonamides are now used against MRSA, widely against gram+/-, but has limited activity against group a strep and enterococci.
Definition
True
Term
Which of the following are key properties of sulfonamides - highly protein bound, hepatic metab, and renal elimination.
Definition
All of them
Term
Which of the following are adverse affects of sulfonamides - kernicterus (bili in brain), crystalluria, hematopoietic disturbances, or hypersensitivity syndromes?
Definition
All
Term
Why do clinicians use combination drugs composed of both sulfonamides and trimethoprim (bactrim aka cotrimoxazole)?
Definition
Because they have a bactericidal action that blocks folate acid synthesis at two points in the enzymatic pathway creating a synergistic affect.
Term
Which of the following are b-lactam antibiotics which inhibit cell wall synthesis at the transpepidation stage - penicillin, cephalosporins, carbapenems, monobactams.
Definition
All
Term
What are the 3 causes of resistance to beta-lactam antibiotics?
Definition
Degradation by bacterial beta-lactamase (inhibitors exist though), decreased drug permeability, altered penicillin binding proteins
Term
T or F: Vancomycin and bacitracin are non ? lactam drugs that also inhibit cell wall synthesis.
Definition
True
Term
T or F: Natural Penicillins: Pen G, Pen VK, Benzathine and Procaine forms are the Drug of choice for Streptococcal infection, syphilis, spirochetes but are Highly susceptible to beta lactamases.
Definition
true
Term
T or F: Antistaphylococcal Penicillins: Methicillin, oxacillin, dicloxacillin…are More stable to beta lactamases, due to modifications near beta lactam ring and have Poor entry into gram negative bacteria.
Definition
true
Term
T or F: Amino Penicillins: Ampicillin, amoxicillin, others… have Enhanced Gram negative coverage (due to amination) and Remain highly susceptible to beta lactamases.
Definition
true
Term
T or F: Antipseudomonal Penicillins: Carbenicillin, Ticarcillin, Piperacillin… have Enhanced Gram negative coverage (due to extensive side chain addition) and are Highly susceptible to beta lactamases.
Definition
True
Term
Which of the following are toxicities related to beta-lactams - hypersensitivity, NVD, neutropenia, GI: psuedomembranous enterocolitis or antibiotic diarrhea, neuro/cation toxicity.
Definition
All of them
Term
How are penecillins delivered to a patient?
Definition
Iv or IM, although amoxicillin is well-absorbed via GI
Term
T or F: Penicillins enter the CSF just as well as the serum.
Definition
False, it widely distributes in tissues but doesn’t enter the CNS unless there is inflammation
Term
How do cephalosporins work differently from penicillins?
Definition
They don’t, they both bind the PBP
Term
Beta-lactamase inhibitor drugs do not have intrinsic anti-bacterial activity unless combined with a beta-lactam drug, do those combo drugs have comparable activity against staph as methicillin?
Definition
Yes
Term
T or F: NONE of the cephalosporins are active against enterococci, coagulase negative staphylococci, or Listeria monocytogenes.
Definition
True
Term
What is the difference between spores and anaerobic bacteria?
Definition
Spores are DNA containing structures that are extremely tough that can create a cell, whereas anaerobes are already formed cells that cannot grow in the presence of oxygen and having varying levels of tolerance to it.
Term
Name the bacteria with these features - gram positive rod, anaerobe, creates H2S and CO2, cause gas gangrene due to alpha and beta toxin, food poisoning spores cause growth and release enterotoxin, alpha toxin is lecithinase (phospholipids), beta toxin is responsible for necrotizing enteritis.
Definition
Clostridium perfringens
Term
Name the bacteria with these features - gram + rod, forms terminal spores, found in soil, tetanolysin (hemolysis)toxin, causes lockjaw and muscle spasm, highly sensitive to oxygen, tentanospasmin cleaves to A and B which block inhib neurotrx that is irreversible.
Definition
C. tentanus
Term
Name the bacteria with these features - gram + rod, forms spores that are heat resistant, toxins are heat sensitive and due to vegetative growth, disease of Ach inhib is a result of toxin intoxication not bacterial destruction, growth in absence of normal flora (kids).
Definition
C. botulinum
Term
Name the bacteria with these features - gram + rod, forms spores, causes antibiotic resistant GI disease such as diarrhea and psuedomem colitis due to toxins A and B, treated by oral metronidazole or vancomycin, fecal-oral or nosocomial transmission.
Definition
C. difficile
Term
Name the bacteria with these features - gram + bacillus, no spores, aerobic, leathery skin pseudomembrane in pharynx, damage due to phage encoded A and B toxin that inhibits cell protein creation, treated with penicillin and prevented with vaccine.
Definition
Corynebacterium diphtheriae
Term
Name the bacteria with these features - gram +, aerobic, spores, two toxins that exist in rice one that is pre-formed and the other is a heat labile toxin due to bacterial growth, diseases caused are vomiting and diarrhea.
Definition
Bacillus sereus
Term
Name the bacteria with these features - Gram positive filamentous bacilli, spores, anaerobes, a chronic granulomatous lesion in the sinuses can form, Yellow “sulfer granules” sometimes appear in the abscesses, colonizes UR tract/GI/Female genital tract.
Definition
Actinomyces
Term
Know the Hep B serology for diagnosis.
Definition
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