micro test for review - fall 2011

8/2/2019 Micro Test for Review - Fall 2011

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Terms Definitions

What do we call antibioticsthat kill gram negative andgram positive bacteria?

Broad spectrum drugs (antibiotics) are effectiveagainst both gram negative and gram positivebacteria.

What do we call it when we

give the patient 2 or 3 differentantibiotics a once? Why wouldwe do that?

Combination chemotherapy. Pathogens are capable

of becoming resistant to a single agent, butcombination chemotherapy (using more than onedrug) makes it more difficult for the pathogen todevelop resistance.

What is chemotherapeuticindex?

The relationship between toxicity of a compound forthe body and the toxicity for parasites.

If a drug has a lowchemotherapeutic index, what

does that mean? Is that goodor bad?

Drugs that have a low chemotherapeutic index ofteninhibit pathways or attack structures found in the

host cells. For example, cancer cells closelyresemble normal body cells, therefore, it is difficultto poison the cancer cells without poisoning thebody. A low chemotherapeutic is bad. The larger thetherapeutic index, the better the chemotherapeuticagent, and the less toxic it is to the host. Drugsoften have high therapeutic indexes if the target ofthe drug is a structure or pathway not found in thehost organism.

A drug has a low selectivetoxicity. Is that a good or badthing?

Selective toxicity is the ability of a chemical or drugto kill a microorganism without harming its host,therefore, a low selective toxicity is a bad thing.

Name four major methods bywhich antibiotics work:

1) inhibit cell wall synthesis2) inhibit protein synthesis3) inhibitor of nucleic acid synthesis4) inhibit folic acid synthesis

Penicillin is made by a

______?

fungus (mold/penicillium)

Who discovered penicillin? Fleming

How does penicillin harmbacteria?

Penicillin is in a group of "beta-lactam" drugs thatwork by inhibiting the cross-linkages between theNAM-NAG layers of the peptidoglycan cell wall.Results in faulty cell wall and lysis of bacteria:bacteriocidal.


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What are three problems withpenicillin?

1) overuse has led to resistance. Many bacteriahave beta-lactamase (penicillinase), an enzymewhich inactivates the penicillin.2) narrow spectrum3) anaphylactic reaction: many people allergic

What types of microorganisms

are affected by pencillin?

primarily for staph and strep infections- also syphilis

What do we mean bysemisynthetic penicillin? Arethey only good for grampositive microorganisms?

Altered natural beta-lactams create semisyntheticderivatives of penicillin. These are synthetic andmore expensive. They have a broader spectrumthan penicillin due to their modified chemicalstructures.

Why do they add clavulinicacid to penicillin?

The clavulinic acid inactivates the penicillinasemade by bacteria.

What is beta-lactamase? A bacterial enzyme that catalyzes the hydrolysis ofthe lactam ring in some penicillin antibiotics,rendering them ineffective. Beta-lactamase is alsoknown as penicillinase.

Cephalosporins are describedas first generation, secondgeneration, and thirdgeneration. What is thedifference?

first generation are generally used for grampositives. They are narrow spectrum. secondgeneration are more broad. They kill enterics (gram- and some gram +). Third generation killspseudomonas and is broad spectrum killing gram -and even more gram +.

How do these work? They work like penicillin by inhibiting cell wallsynthesis. They do this by inhibiting the crosslinkages between the NAM and NAG layers of thepeptidoglycan cell wall. The cephalosporins areresistant to beta lactamase enzyme.

Why are these drugs betterfor some people thanpenicillin?

They are active against more organisms and do notcause as many allergic reactions as penicillin.

Name four other drugs thatinhibit the synthesis of the cellwall:

1. Augmentin2. Bacitracin3. Vancomycin4. Isonizid

Which of these drugs is used vancomycin


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to treat MRSA?

Which of these drugs is fortopical application?

bacitracin

Name a drug that inhibits thecell wall synthesis in

Mycobacteria:

isoniazid and ethambutol

Why can we give drugs thatdisrupt ribosomes? Wouldn'tthat also affect humanribosomes?

The drugs only affect the 30s ribosomes inprokaryotic cells. Human cells are not affectedbecause they have 40s ribosomes since they areeukaryotic.

Aminoglycosides are effectiveagainst gram _____ bacteria

negative

What are some side effects ofaminoglycosides?

1. hearing loss2. kidney damage

Tetracycline is considered a___________________________ antibiotic.

broad spectrum

Tetracycline is effectiveagainst intracellular bacteriasuch as:

chlamydia and rickettsia

Tetracycline is effectiveagainst bacteria without a cellwall such as:

mycoplasma

What is the problem withtetracycline and children?

discolors teeth and affects bone.

What is special aboutchloramphenicol?

it gets through the blood brain barrier and is greatfor treating meningitis. (also treats rickettsia and

chlamydia)

What about the problemassociated with it? Howserious is that?

toxicity in children--> aplastic anemia. This is veryserious as it causes supression of bone marrow andloss of production of WBC and RBC

Which patients geterythromycin?

patients who are allergic to penicillin or theorganism is resistant to penicillin. Erythromycin hasa low toxicity.


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Name the 2 diseases that areoften treated with this drug:

Legionella and Mycoplasma

Clindamycin is a broadspectrum antibiotic. Suchantibiotics have beenassociated with

pseudomembranous colitis.What is that?

Pseudomembranous colitis is an increase in thenumber of Clostridium difficile which produces atoxin in the GI tract. This is a serious complication.

Name a drug given to combatVRSA:

oxazolidinones and streptogramins

How do rifampin andquinolones work?

they inhibit nucleic acid synthesis

When is rifampicin given? for TB and meningitis (also against Rickettsia and

Chlamydia)

What is one of it's disturbingside effects?

"red man syndrome" --> occurs when rifampicin isgiven all at once. This causes the mast cells andbasophils to degranulate thus causing a "red" effecton the skin. This can be prevented by giving smallerdoses over a period of time.

What is a side effect ofquinolones?

not given to pregnant women because it can causecartilage development in the newborn to be

affected.

How do sulfa drugs work? inhibit folic acid synthesis. They act asantimetabolites by mimicking a compound (PABA)needed by bacteria to make folic acid.

What is the advantage ofgiving sulfa drugs togetherwith trimethoprim?

in combination, they block two steps in theformation of folic acid. This ensures not othersynthesis of folic acid occurs.

When are sulfa drugsprescribed?

urinary tract infections, pneumocystis, andpneumonia

Name an antifungal agentgiven for systemic fungalinfections:

anphotericin B

Name an antifungal agentgiven topically for skin fungus:

imidazoles


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How does acyclovir work? blocks nucleic acid synthesis by incorporating a"wrong base" into the DNA of a virus so there is noprotein synthesis and therefore no viral replication.

Why is it so difficult to comeup with antiviral agents?

because viruses lack organelles and have no cellwall.

Why would interferon seemlike a good drug to give forviral infections?

because it blocks the formation of viral proteins atthe ribosome (hep. C)

How does AZT work? it changes base analogs- incorporates the wrongbase into the viruses DNA so there is no proteinsynthesis and thus no viral replication.

Some antiviral drugs areneuraminidase inhibitors.

Which virus did we discussthat has neuramindase as oneof it's spikes?

influenza

What would a patient with aTrichomonas vaginalisinfection likely be treatedwith?

metronidazole- it prevents replication andtranscription of anaerobic protzoan (and anaerobicbacterial) infections.

Name an antimalaria drug: chloroquine--> mechanism not well understood but

it's believed that it blocks the metabolism since itaccumulates in RBC's which affects the plasmodia

Explain how the disk diffusionmethod can be used to testbacteria against antibiotics:

A disc containing a certain antibiotic is placed on aspread plate of a certain bacteria. If a clear ring isseen around the disc, then the antibiotic isconsidered a good treatment for that bacteria. If noclearing is seen around the ring, then obviously thatantibiotic cannot kill that bacteria.

Is laryngitis considered to bean upper respiratory or lowerrespiratory infection?

upper respiratory

Are there normallymicroorganisms in therespiratory tract?

in the upper respiratory system- yes.

For Streptococcus pyogenes, 1. M. protein 2. hyaluronidase 3. streptokinase 4.


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Name three virulence factors: C5 peptidase

Name a type IIIhypersensitivity that candevelop after strep infections:

glomerulonephritis

Name the exotoxin made that

turns the skin red:

erythrogenic toxin- causes scarlet fever

Name the type of hemolysiscaused by Streptococcuspyogenes:

beta hemolytic- causes a complete lysis of RBC

What microorganism causesacute epiglottitis?

Hemophilus influenzae

Name 3 common bacteria that

can cause sinusitis andbronchitis:

1. Streptococcus pneumoniae

2. Hemophilus influenzae3. Staphylococcus aureus

Name the causative agent fordiptheria:

Corynebacterium diphtheria

What is a pseudomembrane? grows again after scraping off. (bloody) Made ofdead epithelial cells and clotted blood. This"pseudomembrane" may obstruct air passageways.

Which exotoxin is made bythese bacteria? Which organsdoes it affect?

diphtheria toxin. It inhibits protein synthesis and canaffect heart and nerves.

Can this disease be treatedwell with antibiotics?

it's treated with an antitoxin, also penicillin anderythromycin to stop bacterial growth.

How are children vaccinatedagainst diphtheria?

yes- children are immunized with a toxoid.

How is diphtheria treated? patients are given antitoxin and also penicillin anderythromycin to stop bacterial growth.

Name two types of virusesthat cause the common cold:

Rhinovirus, Corona virus and Adenovirus

How many types ofrhinoviruses are there?

over 100

Name the causative agent for Bordetella pertusis


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whooping cough:

Name the three phases ofdisease:

1. catarrhal stage: long prodromal phase2. paroxysmal stage: cilia immobilized due toexotoxin- uncontrollable coughs with difficultybreathing. May last 6 weeks3. convalescent stage:

Which exotoxin is made andwhat does it do?

tracheal cytotoxin

What causes coughingattacks?

the cilia are immobilized due to the exotoxin anduncontrollable coughs ensue

How are children vaccinatedagainst this disease?

DTaP

Should antibiotics be given? Ifso, when?

erythromycin can be effective if given early

Name the causative agent forclassic lobar pneumonia:

Streptococcus pneumoniae

Does this agent display alphaor beta hemolysis?

alpha hemolytic

How can this type of

pneumonia be treated?

penicillin

Is there a vaccination? yes- it's called pneumovax which is a combinationof 23 capsule antigens to cover most 85 serotypes

Who is at risk? ...

Name a causitive agent ofhemorrhagic pneumonia:

Klebsiella pneumonia

How high is the mortality? high due to chronic ulceration and destruction ofalveoli

What is the causative agent inwalking pneumonia?

Mycoplasma pneumoniae

How is it treated? erythromycin

Where are Legionella bacteriafrequently found?

likes wet, moist environments (humidifiers, AC)


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What does it mean thatLegionella bacteria arefastidious?

they are picky eaters- they need specificenvironments to survive

What are symptoms and signsof this disease?

fever, fluid in lung, chest pain

Can this type of disease betreated?

yes with erythromycin

What is the agent that causestuberculosis?

Mycobacterium tuberculosis

Is the agent aerobic oranaerobic?

obligate aerobe

What is meant by a Ghon

complex?

primary tubercle with calcium deposits and

lymphode involvement seen on x-ray

What is a granuloma? chronic inflammation with wall created by immunecells to keep infection contained. Granulomas areseen in leprosy, TB adn later stages of syphilis

When is a patient contagious?(concerning TB)

A person with TB disease may remain contagiousuntil he/she has been on appropriate treatment forseveral weeks. However, a person with latent TBinfection, but not disease, cannot spread the

infection to others, since there are no TB germs inthe sputum

What is meant by thesecondary stage of TB?

reactivation. if tubercle breaks into bronchus-->highly infectious. if tubercle continues to grow-->consumption.

What is military TB? disseminated: in immunocompromised host. spreadwith high death rate to many tissues. Bacteria gainaccess to blood and spread

What is a Mantoux test? positive skin test through intradermal injection ofantigen (PPD- purified protein derivative)

If a patient has a positiveMantoux test, is that patientcontagious?

A positive skin test means that a person has beenexposed to TB germs sometime during his life. Itdoes not indicate that a person has TB or iscontagious


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How is a Mantoux testdifferent from a Tine test?

a tine test : times with antigens pressed into skinand wait 48 hours > 15mm positive.

What type of immune reactiondoes this test for?

type IV hypersensitivity

Name four drugs used to treat

Tbc. How long are they given?

The most common drugs used to treat TB are:

IsoniazidRifampin (Rifadin, Rimactane), Ethambutol(Myambutol), and Pyrazinamide. With tuberculosis,you must take antibiotics for at least six to ninemonths

What is a BCG vaccination? a vaccine against tuberculosis that is prepared froma strain of the attenuated (weakened) live bovinetuberculosis bacillus, Mycobacterium bovis, that haslost its virulence in humans --> also prepared from

Mycobacterium tuberculosis. The bacilli haveretained enough strong antigenicity to become asomewhat effective vaccine for the prevention ofhuman tuberculosis. At best, the BCG vaccine is80% effective in preventing tuberculosis for aduration of 15 years; however, its protective effectappears to vary according to geography.

What is meant by MDR-

tuberculosis?

multi drug resistant strains

What causes influenza? the Influenza virus (Orthomyxoviridae ssRNA-)

What are the two spikes onthe influenza that help withtheir classification?

neuraminidase: penetrates the mucus;hemagglutinin: attaches to RBC

What is meant by antigenicdrift?

antigens change slightly so that immune systemsare less effective against them. (swine flu in 1918-

19 over 40 million people died)What is meant by antigenicshift?

more severe changes that can cause newpandemics

How long is the incubationtime?

1-3 days

How is this diseasetransmitted?

respiratory droplets


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Is there a vaccination? yes. the annual flu shot. CDC selects certain strainsthat are included.

Who is most susceptible tosevere RSV infections?

children under one year. older children and adultshave a less severe infection.

What CPE does RSV cause? syncytia- large multinucleated cells in the lung

How is Hantavirustransmitted?

inhalation of mouse feces carried by deer mouse

What are some complicationsof the disease?

begins with fatigue and lethargy, then coughing toshock as lungs fill with fluid. 50% mortality rate

Name the type of fungalrespiratory disease obtainedfrom chicken houses in the

Midwest:

histoplasmosis

Name the type of fungalrespiratory pneumonia that isseen in HIV patients:

pneumocystis pneumonia

Why is Bacillus anthracis aconcern in bioterrorism?

B. anthracis is the easiest to grow and is the mostenvironmentally stable. It's spores can remainairborne for up to a day- therefore infecting manypeople at once.

What type of anthrax is thebiggest concern?

inhalation since it is most severe causing coughing,fever, aches, nausea and lethargy caused byanthrax toxin which kills human cells.

Concerning Staphylococcusinfections, give examples ofenzymes that act as virulencefactors:

hemolysins, hyaluronidase and coagulase

What is exfoliatin? What doesit do?

exotoxin- causes scalded skin syndrome which is ared peeling rash and also a sign of toxic schocksyndrome. Occurs with high fever and danger ofsepticemia

What is the differencebetween folliculitis, anfuruncle, and a carbuncle?

folliculitis: infection of hair follicles (pimples),furuncle: abscess on skin, carbuncle: excessivelylarge furuncle, often accompanied by fever.


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Is Staphylococcus aureuscatalase positive or negative?

catalase positive- it bubbles when hydrogenperoxide is added.

Name two causative agents ofimpetigo:

Staphylococcus aureus and Streptococcuspyogenes

What do you call small fluid

filled blisters?

...

What do you call large fluidfilled blisters?

vesicle

What do you call large, flatred spots?

macule

What do you call small pusfilled lesions?

pustule

Which bacteria make M-protein? What does that helpwith?

Streptococcus pyogenes- M protein is strongly anti-phagocytic and is a major virulence factor. It bindsto serum factor H, destroying C3 convertase andpreventing opsonization by C3b

How are Streptococcus andStaphylococcus transmitted?

by direct contact or fomites

Concerning Streptococcus

infections, name the exotoxinthat causes a rash:

erythrogenic toxin: scarlet fever

Name three other skindiseases caused byStreptococcus:

erysipelas, pyoderma, necrotizing fascitis

How are rubella and rubeolatransmitted?

respiratory secretions

When is infection with rubellaespecially a concern?

it is teratogenic and can cause congential problems--> loss of hearing and heart problems. Especiallydangerous in first trimester of pregnancy

When are children vaccinatedagainst rubella?

vaccinated with the MMR around 1 year of age

Which infection is indicated byKoplik spots in the mouth?

measles


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Name some complications ofrubeola:

pneumonia, measles encephalitis, SSPE (subacutesclerosing panencephalitis)

How serious is SSPE? it is fatal and occurs 6- years after a rubeolainfection

The chicken pox virus belongs

to which family of viruses?

Herpesviridae

How is this transmitted? respiratory or through lesions

Describe the signs of thisdisease:

rash to pustules that usually begin on trunk andspread

Where does this virus residein latent infections?

ganglia

How does shingles develop? recurrent latent - dormant virus infection.Varicellovirus remains dormant in ganglia and thencan reactivate causing a one sided dermatoneoutbreak.

Is there a vaccination? yes

What is Reye syndrome? neurological damange in children following chickenpox who also received aspirin

What is the cause of warts? Papilloma virus

What is the cause of fifth'sdisease?

Parvovirus B19

Where do Herpes simplex Iand II reside in latentinfections?

I- commonly in the trigeminal nerve ganglion; II-commonly in the sacral nerve ganglion

What is the cause of

ringworm?

Tinea

How is ringworm treated? topical drugs (clotrimazole) or griseofulvin (orally)

What is the name given to aCandidia infection in themouth?

thrush

Who gets this type ofdisease?

babies or immunocompromised


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A skin wound fills with pus.Which bacteria are commonconcerns?

Staph and Strep

Name two types of Clostridiainfections in wounds:

Clostridium perfringens and Clostridium tetani

How is gas gangrene treated? treatment is usually amputation and antibiotics.Inaddition to surgery and antibiotics, hyperbaricoxygen therapy (HBOT) is used and acts to inhibitthe growth of and kill the anaerobic C. perfringens

Name the primary cause ofinfectious blindness:

Chlamydia trachomitis

How is it transmitted? vector by flies but also by direct transmission

Why do newborns receiveantibiotic salve in their eyes?Which two infections areespecially of concern?

to prevent Chlamydia trachomitis conjuctivitis frompassing through the birth canal and also Neisseriagonorrheae

Which agent is a concern inanimal bites?

Pasteurella

Name the type of meningitisthat would most like affect

newborns:

1. Streptococcus agalactiae2. Escherichia coli

Name the type of meningitisthat would most likely affectpreschool children:

Hemophilus influenzae

Name the type of meningitisthat would most likely affectschool age children:

Neisseria meningitidis

Name the type of meningitisthat would most likely affectadults:

Streptococcus pneumoniae

What is the gram reactionseen in meningococcemia?

gram negative

What are petechiae? is a small (1-2mm) red or purple spot on the body,caused by a minor hemorrhage (broken capillary


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blood vessels)

Why are siblings treated withrifampin?

...

How is Listeriamonocytogenes transmitted?

foodborne

What is another name forleprosy?

Hansen's disease

Name the causative agent ofleprosy:

Mycobacterium leprae

What is the generation time ofthis microorganism?

12 days

Why are the fingers, toes andnose most affected? it causes a loss of the sensation of the skin andthen a progressive loss of appendages, facialfeatures

Which type is moreaggressive?

lepromatous type

Does this disease affect thePNS or CNS?

PNS

Name a nervous systemdisease that is caused by apicorna virus:

poliomyelitis

What signs develop when theanterior gray horn of thepatient is affected?

that is the paralytic type - this affects the motorneurons. Only affects 2 % of people. Most just haveno symptoms or minor ones such as a sore throat,nausea, and headache

How are children vaccinated

against this disease?

since some people actually developed polio from

the attenuated polio oral vaccine (or from avaccinated infant because the virus is excreted withthe feces), they now use the injected kind which isinactivated.

What is post polio syndrome? 20 years after polio as nerve cells are exhaused.

Which bites are mostdangerous as far as rabies is

wildlife since most dogs are immunized againstrabies. Many animals act as reservoirs (bats)


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concerned?

What type of treatment wouldthere be?

after a bite, antibodies are given against rabies. Ifdisease manifests itself, there is no treatment.

What are the signs of rabies? headache, fever and once it reaches the CNS-hydrophobia (swallowing is very painful) and

seizures.

Name a fungal encephalitisthat is caused by inhalingspores in soil and birddroppings:

cryptococcal meningoencephalitis

Which group of people is mostsusceptible?

healthy people but AIDS patients have a hard timefighting it due to lack of thelper cells

How would this be treated? amphotericin B

How is African sleepingsickness transmitted?

carried by Tsetse fly

How does Trypansoma avoidthe immune system?

by changing it's antigens- antigenic shift

How successful is treatmentwhen the CNS has been

involved?

now very good if CNS has been involved.Pentamidine is available for treatment.

Name a disease caused by aprion:

Creutzfeld Jakob disease (Mad cow)

Is there effective treatment? No- death is imminent. There is no treatment for thisdisease.

micro test for review - fall 2011

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