chapter 11,12,14

1. Explain mucociliary clearance as defense in the respiratory system.

Mucociliary clearance is a vital defense mechanism in the respiratory system that protects the lungs by trapping and removing inhaled particles, pathogens, and debris. (with mucus and cilia)

2. Streptococcal pharyngitis a. Causative agent: b. Transmission: c. Symptoms: d. What is its hemolytic reaction? e. Lancefield classification: f. Significance of pili and capsule g. M protein: h. Scarlet fever: i. Erythrogenic toxins: j. What is rheumatic fever and rheumatic heart disease?

Caused by Streptococcus pyogenes

Group A (Lancefield classification)

Beta-hemolytic

spreads through respiratory droplets

Virulence factors

Capsule

Pili

Symptoms include high fever, inflamed pharynx, coughing, swollen lymph nodes in neck, and swollen tonsils.

The organism secretes toxin that damages pharyngeal cells.

Recovery is hastened by antibiotics.

• Scarlet fever is strep throat with a rash.

Rash caused by erythrogenic toxins.

Toxins cause bleeding in the skin.

• Rheumatic fever is a serious complication.

Fever and pain

Heart tissue inflammation

Heart valve damage

A hemolytic reaction especially beta is a complete break down of red blood cells.

3. Diphtheria a. Causative agent: b. Transmission: c. What is the action of the exotoxin? d. Symptoms: e. What is the pseudomembrane? f. Treatment: g. Prevention:

Caused by Corynebacterium diphtheriae

Symptoms due to exotoxin

Exotoxin inhibits protein synthesis in epithelial cells by inactivating 80 S ribosomes.

Combination of dead tissue, WBCs, and scar tissue form pseudomembrane

Pseudomembrane can cause airway blockages.

Air passageway may swell shut.

Treated with antibiotics and antitoxin

Prevented by DTaP vaccine

4. How do bacteria of the URT reach the middle ear to cause otitis media?

Acute otitis media—middle ear infection

Bacteria from URT can gain entry to middle ear by Eustachian

(auditory) tube.

Bacteria from the upper respiratory tract reach the middle ear by traveling through the Eustachian tube, which connects the nasopharynx to the middle ear. When this tube becomes blocked or inflamed, pathogens can move upward and cause otitis media.

5. Common cold: a. Causative agent: b. Transmission: c. Symptoms:

Rhinoviruses cause the commoncold.

Virus transmitted by respiratory droplets or fomites

Symptoms:

Sneezing

Sore throat

Runny or stuffy nose

Mild aches and pains

Hacking cough

Illness lasts between 7 to 10 days.

Virus transmitted by respiratory

droplets or fomites.

More common in fall and spring

6. Whooping cough a. Causative agent: b. Transmission: c. What is the physiological action of the major exotoxin? i. Stages of disease 1. Catarrhal stage 2. Paroxysmal stage 3. Convalescent stage ii. Treatment: iii. Prevention:

Caused by Bordetella pertussis

Whooping cough (pertussis) is transmitted through respiratory droplets.

Most important exotoxin immobilizes cilia

More severe in small children

• Catarrhal stage:

Buildup of excessive discharge in respiratory tract

Most contagious stage

• Paroxysmal stage:

Dead cells and mucus accumulation over 2–4-week period

Labored breathing

Spasmodic coughing due to paralyzed cilia; can’t eliminate mucus

Rapid-firing coughs in one exhalation followed by high-pitched whoop.

This is due to forced inhalation over a partially closed glottis.

• Convalescent stage:

Persistent coughing decreases

Treated with antibiotics

Prevented by DTaP

Increasing due to:

Not getting vaccinated

Immunity declines of time

Evolution of resistant strains

7. Influenza a. Causative agent: b. Transmission: c. Symptoms: d. Role of hemagglutinin (H) spike: e. Role of neuraminidase (N) spike: g. How does integrated pig-duck farming contribute to pandemic strains. h. What are the characteristics of influenza A virus? i. What causes most of the deaths due to influenza? Who is the most vulnerable?: k. Prevention: l. Treatment:

Influenza is caused by the influenza viruses, primarily Influenza A and Influenza B, which are responsible for seasonal flu epidemics.

• Influenza is transmitted mainly through respiratory droplets

Two spike proteins are found in envelope:

Hemagglutinin: for attachment & penetration

Neuraminidase: for release from host cell Virus attacks epithelial cells of nasopharynx and tracheo-bronchial tree.

Most pandemic strains arise in southern Asia due to integrated pig-duck farming. Pigs are a reassortment vessel since they can be infected with avian, human and swine strains.

Influenza virus characteristics:

Orthomyxoviridae

ssRNA, helical, enveloped

Each strand is surrounded by a nucleocapsid protein.

Matrix protein surrounds core RNA segments

Symptoms of influenza:

Incubation period 1-4 days

Chills

Fatigue

Headache

Fever can rise to 40 degrees C

Pain most pronounced in chest, back, and legs

Sore throat

Nasal congestion

Sneezing

Tight chest

* Most flu deaths are caused by spread to the lungs or secondary bacterial pneumonia.

*Most susceptible groups include infants, small children, elderly, and immunocompromised.

• Influenza is prevented with vaccines (People that are allergic to chickens or eggs are not recommended to take this vaccine)

Treatment:

Several antiviral agents can lessen the course of infection:

Zanamivir (Relenza)

Oseltamivir (Tamiflu)

Both drugs target N spikes and block viral release.

8. Covid-19 a. Causative agent: b. Transmission: c. Symptoms: d. Complications: e. Prevention: f. treatment

Caused by SARS-CoV-2 virus

Spread by respiratory route or fomites.

Symptoms:

Temporary loss of taste and smell

included fever, dry cough, and difficulty breathing

Virus multiplies in the pneumocytes of the alveoli

Alveolar infection triggers cytokine release, causing fluid buildup

Complications:

can cause complications affecting nearly every organ system, including the lungs, heart, brain, kidneys, blood vessels, and long‑term post‑viral syndromes such as Long COVID.

Prevention:

Three vaccines are used in the United States

Treatment:

Treatment includes remdesivir, dexamethasone, and antibody treatments

9. Tuberculosis a. Causative agent: b. Acid fast c. Transmission: d. Symptoms: e. Distinguish between latent tuberculosis and active tuberculosis. f. How is the tubercle formed? g. What is miliary tuberculosis? h. What is the Mantoux or tuberculin test? What is induration? What does a positive tuberculin test indicate? What is the next step after a positive tuberculin test? i. What has made tuberculosis treatment precarious? j. Why are simultaneous infections of tuberculosis and HIV dangerous? k. What is BCG?

Caused by Mycobacterium

tuberculosis

Acid-fast bacillus

Waxy cell wall resistant to drying and

disinfectants

18 hour generation time

Tuberculosis was formerly known as

consumption.

Disease is a worldwide threat.

Factors that facilitate spread

Poor ventilation

Overcrowding

Malnutrition

AIDS

Infection is arrested in 90% who

become infected. This is called

latent tuberculosis.

This is due to the action of the immune

system and host defenses.

Infection progresses in remaining

10% of people.

This is called primary active

tuberculosis.

Secondary active tuberculosis occurs

when someone with latent TB has a

change in immune status.

85% of infections are respiratory.

Respiratory symptoms:

Fatigue

Chronic cough

Difficulty breathing

Chest pain

Spitting up bloody sputum

Fever

Night sweats

Weight loss

Miliary tuberculosis occurs when

infection spreads from the primary site

into secondary sites

10. What are common causes of nosocomial pneumonia?

11. Pneumococcal pneumonia a. Causative agent: b. Transmission: c. Symptoms: d. What is a typical pneumonia? e. Who is at risk? f. Treatment: g. Prevention:

Caused by Streptococcus

pneumoniae

Gram-positive

Diplococci

Encapsulated

Over 90 capsular serotypes

Causes 80% of serious pneumonia

Organism resides in upper respiratory

tract

May invade lower respiratory tract

Risk groups include infants, elderly,

alcoholics, malnourished, &

immunologically compromised

Typical pneumonia

Symptoms include high fever, sharp

chest pains, difficulty breathing, and

rusty sputum

Pneumonia involves the alveoli of the

lungs. The infection can impair

respiratory gas exchange.

Damage to respiratory membrane can

allow fluids to leak in alveoli, displacing

space for air or causing collapse.

Treated with antibiotics

Vaccines are available

12. Mycoplasma pneumonia a. Causative agent: b. Transmission: c. Symptoms: d. What is atypical pneumonia? e. What is unique about Mycoplasma? f. Why isn’t penicillin effective? g. Treatment:

Caused by Mycoplasma

pneumoniae

No Gram reaction

No cell wall

No sensitivity to penicillin

Tiny bacterium about 0.2 micrometers

Pleomorphic cells

Fried egg-like colonies

Atypical pneumonia

Symptoms include chronic cough,

low-grade fever, fatigue, and

headache

Common in institutional settings

Very contagious disease

Patients recover spontaneously

Recovery can be hastened by

antibiotics

13. Legionaire’s disease a. Causative agent: b. Transmission: c. Symptoms: d. What are the common sources of the organism? e. Treatment:

Caused by Legionella pneumophila

Gram-negative rod

Silver stain is best because of weak Gram-

reaction

Aquatic bacterium

Multiplies in amoebae

Biofilm-former

Name was given after outbreak at

American Legion convention in

Philadelphia in 1976. 221 affected, 34

died.

8000-12,000 hospitalizations each year

2-10 day incubation period

Person-to-person transmission does

not occur.

Common sources of bacteria: air

conditioning cooling towers, air

conditioners, humidifiers, hot-tubs,

and showers

Bacteria resistant to heat and

chlorine

Symptoms include coughing, fever,

chills, breathing difficulties

Necrotic pneumonia with

inflammation

Infects alveolar macrophages

Treated with antibiotics

14. Respiratory syncytial virus a. Causative agent: b. Transmission: c. Symptoms: d. Age class at risk: e. Cytopathic effect seen in infected cells: f. Treatment:

Causative agent is Respiratory

Syncytial Virus (RSV).

Paramyxoviridae, SS RNA, helical,

enveloped.

Common serious LRT infection of

infants and toddlers.

Virus causes pneumonia.

Infection is localized in bronchioles

and alveoli.

Virally-infected cells fuse to form a

giant multinucleate cell called a

syncytium.

95% of children under five have

been exposed to the virus.

Disease causes 75,000-125,000

hospitalizations each year.

4500 die

Treated with ribavirin

15. Fungal respiratory diseases, causative agent, symptoms, treatment a. Histoplasmosis b. Pneumocystis pneumonia c. Aspergillosis

HISTOPLASMOSIS

Causative agent is

Histoplasma capsulatum

Ascomycota

Common in Ohio River valley

80-90 % of people in this area react

positively to the histoplasmin

hypersensitivity test.

Thermal dimorphic fungus

Is a mold in the soil

Becomes a yeast in the body

PNEUMOCYSTIS PNEUMONIA

Causative agent is Pneumocystis

jiroveci

Formerly thought to be a protozoan

Has complex life cycle in the alveoli

of lungs

Transmitted by person-to-person

transmission by respiratory droplets

Commonly found in the alveoli of

humans and animals

Causative agents are Aspergillus

species, particularly A. fumigatus.

Mitosporic

Ascocomycota

Common mold in environment

May cause highly invasive

pulmonary and systemic infections in

immunocompromised individuals

Invades blood vessels

Causes endocarditis

Aspergillus fumigatus

ASPERGILLOSIS, CONT.

Another risk factor for aspergillosis

is inhaling an overwhelming number

of spores.

Aspergilloma is a round mass of

mycelium growing in the lungs.

Has to be surgically removed.

Aspergillosis is treated with

voriconazole.

Aspergilloma in lung

1. What are the differences among the following? a. Synthetic b. Antibiotic c. Semisynthetic

Synthetics are antimicrobial agents synthesized by chemists.

• Antibiotics are antimicrobial agents synthesized by microorganisms.

Most “antibiotics” are really semisynthetics. Base molecules,

synthesized by microorganisms, are modified by chemists.

• To increase effectiveness

• To target certain bacteria

2. What is selective toxicity? What is the toxic dose, therapeutic dose, and therapeutic window?

Selective toxicity states that the antimicrobial drug harms the pathogen, but not the patient.

• Therapeutic dose refers to the concentration of the antimicrobial drug that effectively destroys the pathogen.

• Toxic dose refers to the concentration of the antimicrobial drug that harms the patient.

• Therapeutic window is the concentration range of the antimicrobial drug that is tolerated by the patient but will eliminate the pathogen

3. What is the difference between a narrow-spectrum drug and a broad-spectrum drug?

Broad-spectrum drugs affect a large range of bacteria.

Narrow-spectrum drugs affect a small range of bacteria.

4. What are the common sources of antibiotics?

Bacteria

• Streptomyces and closely-related Actinobacteria

• Bacillus

Fungi

• Penicillium chrysogenum

• Cephalosporium acremonium

5. List the roles of antibiotics in microbial communities?

Functions of antibiotic production is

multidimensional, beyond microbial

weapons.

• Other functions include:

• Chemical cues

• Synergistic signals to induce

cooperation

• Competitive manipulators to allow

some species to flee to avoid

competition

6. What is an antimetabolite? What is the mode of action of sulfa drugs? What kind of enzyme inhibitor are sulfa drugs?

Antimetabolites are synthetic drugs that

Sulfonamide drugs act as competitive inhibitors of a bacterial enzyme involved in folic acid synthesis.

• target key microbial enzymes.

7. What is the mode of action of quinolone drugs? Name some examples.

Quinolone drugs are synthetic.

They interfere with DNA gyrase that is needed to unravel the double helix during replication.

• Examples are levofloxacin and ciprofloxaci

8. What is the primary physiological target of penicillin and cephalosporin drugs? What are the advantages of cephalosporin drugs over penicillin drugs?

Penicillins target cell wall synthesis.

Cephalosporin drugs target cell wall synthesis.

Drugs are largely beta-lactamase resistant.

• They can target Gram-negatives because

they penetrate the outer membranes via

porin proteins.

9. What is beta-lactamase?

BETA-LACTAMASE DEGRADES PENICILLIN BY BREAKING BETA-

Beta-lactamase is a bacterial enzyme that breaks down penicillins.

10. What are carbapenems? What is the mode of action? What are they used for? What is CRE?

• Common Gram-negative organisms with this new enzyme are called carbapenem-resistant Enterobacteraceae or CRE.

• Carbapenems are very effective β‑lactam antibiotics used to treat severe or multidrug‑resistant bacterial infections

• Carbapenems kill bacteria by binding to penicillin‑binding proteins (PBPs) and blocking cell‑wall synthesis, leading to bacterial death.

11. What is vancomycin? What is the mode of action? What is vancomycin used for?

Vancomycin is a glycopeptide antibiotic

Targets cell wall synthesis

• Used to treat MRSA

12. What are the cyclic polypeptide drugs? What is the mode of action of bacitracin? What is the mode of action of polymyxin? What is bacitracin and polymyxin used for?

• Bacitracin, a topical antibiotic, affects peptidoglycan synthesis.

• Cyclic polypeptide antibiotics are toxic for internal use.

• Polymyxin B, a topical antibiotic, targets the outer membrane of Gram-negative organisms.

13. What is the primary physiological target of tetracyclines on bacteria? What are tetracyclines used for?

Tetracyclines targets translation.

• Tetracyclines are antibiotics and semi-

synthetics.

• From Streptomyces species

• Tetracyclines block the attachment of

tRNAs to the small subunit.

14. Name some aminoglycosides? What is the mode of action? What are they used for?

Aminoglycosides include streptomycin,

gentamycin, tobramycin, and neomycin.

• Streptomycin was first drug to treat TB.

• From various Actinobacteria

15. What is chloramphenicol? What is the mode of action? What is it used for?

Chloramphenicol is drug of choice for

epidemic typhus.

• Can cause chemically-induced aplastic

anemia

• One of the few antibiotics that can be

autoclaved for microbiological media

• From Streptomyces venezuelae

16. What is the mode of action of macrolides, such as erythromycin? What is the use of erythromycin?

Macrolides are bacteriostatic in action;

from Actinobacteria

• Erythromycin is example:

• Treat Gram-positive infections in

people with penicillin allergies

• Eye drops to prevent Neisseria

gonorrhoeae and Chlamydia

trachomatis conjunctivitis in neonates

• Produces by Saccharopolyspora

erythraea

17. What is the mode of action of rifampin on bacteria? What is it used for?

Rifampin targets transcription.

• Rifampin is a semisynthetic.

• Rifampin inhibits the bacterial form of

RNA polymerase.

• Used to treat TB

18. How do these antibiotic sensitivity tests work?

a. Tube dilution method, minimum inhibitory concentration b. Etest c. Kirby-Bauer test, disc diffusion method

Tube dilution method determines the lowest concentration of drug that will prevent bacterial growth—minimum inhibitory concentration (MIC).

• Method is used to determine therapeutic window.

ETEST uses a strip, impregnated with antibiotic.

• Strip is placed on an agar plate, inoculated with a lawn of bacteria.

Kirby-Bauer test uses small paper disks, impregnated with antibiotics.

19. What is an antibiogram?

An antibiogram is a report that summarizes how well different antibiotics work against bacteria isolated in a specific hospital, clinic, or region.

20. What are antiviral agents? How do they work? What are base analogs?

Antiviral agents interfere with specific steps of the viral replication cycle.

Antiviral agents are drugs that block different steps of the viral life cycle, and base analogs are a major class that mimic natural nucleotides to disrupt viral genome replication.

21. Why are many antifungal drugs toxic to the human body? What are the modes of action of polyenes (nystatin and amphotericin B), azoles, echinocandins, and flucytosines? What is each used for?

Antifungal drugs are often more toxic because they target aspects of eukaryotic metabolism.

Polyenes

• Alter membrane permeability

• Nystatin treats yeast infections.

• Amphotericin B treats severe systemic fungal infections.

• Azoles

• Target sterol synthesis

• Treat dermatophyte pathogens and yeast infections

Echinocandins

• Target cell wall synthesis

• For Candida and Aspergillus infections

Flucytosine

• Inhibits nucleic acid synthesis

• Used for severe systemic fungal infections

• Often combined with amphotericin B

22. What antimalarial substance comes from the chinchona tree? Name some common anti-malarial drugs used today.

Native South Americans recognized that the bark of the cinchona tree could treat malaria.

• Bark contained quinine.

• Most antimalarial drugs are aminoquinolines.

• Chloroquine

• Mefloquine

• Primaquine

• Another antimalarial drug is artemisinin from sweet wormwood.

23. Name some anti-protozoal drugs?

Sulfamethoxazole and trimethoprim

are used to treat some protozoal

infections.

• Inhibits folic acid synthesis

• Metronidazole is a common

antiprotozoal drug.

• Inhibits DNA synthesis

24. What are antihelminthic drugs? Name some examples.

These drugs treat infestations of

parasitic worms.

• Praziquantel

• Mebendazole

• Ivermectin

25. Differentiate among multidrug-resistant strains, extensively drug resistant strains, and totally drug resistant strains.

Multidrug-resistant strains (MDR) are

resistant to several drugs.

Extensively drug-resistant strains

(XDR) are resistant to all but one or two

classes of drugs.

Totally drug-resistant strains (TDR)

are resistant to all drugs.

26. What does ESKAPE stand for? Why is Clostridioides difficile a concern?

MAJOR CULPRITS OF DRUG

RESISTANCE

Remember the acronym ESKAPE:

• E

• Enterococcus faecium

• S

• Staphylococcus aureus

• K

• Klebsiella pneumoniae

• A

• Acinetobacter baumanii

• P

• Pseudomonas aeruginosa

• E

• Enterobacter species

Additionally, Clostridioides difficile, is

another important bacterium that has

become largely resistant.

27. What are the two genetic causes of antibiotic resistance? What are the three types of horizontal transfer?

Mutation is a permanent change in the

DNA.

• Spontaneous mutations occur

• Can lead to antibiotic resistance

Horizontal transfer is passing DNA

among members of the same

generation of organisms.

• Conjugation

• Transformation

• Transduction

• Conjugation is the most common

mechanism of antibiotic resistance.

28. What is the role of persister cells in antibiotic tolerance? How do antibiotics act as a selective agent on populations of bacteria?

Persister cells are often responsible

for antibiotic tolerance.

• Remember that persister cells are non-

dividing cells with low metabolic rates.

Antibiotics act as a selective agent by killing or inhibiting susceptible bacteria while allowing naturally resistant bacteria to survive and multiply, leading to a population dominated by resistant strains.

29. What are the various mechanisms that cause antimicrobial drug resistance?

Bacteria become resistant to antimicrobial drugs through several well‑defined molecular mechanisms, all of which reduce the drug’s ability to reach its target, bind its target, or exert its effect.

30. What are the causes of the global rise of antimicrobial drug resistance?

Prescription abuse

• Prescribing the wrong antimicrobial drug without culturing the pathogen.

• Often the pathogen does not respond to the given antimicrobial drug.

• Prescription misuse by individuals

• Patient stops taking antimicrobial drug when feeling better.

• Patient takes leftover antimicrobial drugs when sick.

• Prescription misuse by health organizations

• Overuse of antimicrobial drugs

• Giving broad spectrum antimicrobial drugs

• Superbugs often develop in healthcare settings.

• Antibiotic abuse in livestock

• Animal feed mixed with low levels of antimicrobial drugs to prevent disease or to promote growth.

• 79% of antibiotic use is for this purpose!

• Animal feedlots are often environments that superbugs develop.

31. How does antibiotic misuse select for resistant strains?

Antibiotic misuse intensifies natural selection, giving resistant bacteria a survival advantage and allowing them to dominate the population. The key idea is simple: whenever antibiotics are used incorrectly, they kill the susceptible bacteria and leave behind the ones that can withstand the drug. Those survivors then multiply.

1. What is the difference between sterilization and sanitation?

• Sanitation reduces the number of pathogenic microbes to safe levels, so they are not harmful to public health.

• Sterilization involves destroying all microbes, spores, and viruses.

 Autoclaving

2. What is the difference -cidal and -static?

“-cidal” means killing, while “-static” means inhibiting (reducing) growth without killing.

3. Differentiate between dry heat and moist heat techniques. How does each kill microorganisms? What are the advantages and disadvantages of each?

• Dry heat methods are characterized by high temperatures and low humidity. Materials to be sterilized is placed in hot air oven at high heat and low humidity.

• Moist heat methods are characterized by low temperatures and high humidity. Require lower temperatures to sterilize and shorter exposure times. Good method for disinfecting water

 Bacterial endospores may survive boiling.

 Most water-borne pathogens do not form endospores. Good for emergencies, infrastructure incapacitation, camping, etc.

4. How long does it take to kill endospores in the dry air oven at 160 degrees C?

Bacterial endospores are killed at 160 degrees C for two hours.

5. Does boiling sterilize? What is the use of boiling for microbial control?

Good method for disinfecting water

 Bacterial endospores may survive boiling.

Good for emergencies, infrastructure incapacitation, camping, etc.

6. What is autoclaving? What is it used for? What is the standard autoclaving pressure, temperature, and time to kill endospores?

Autoclaving uses steam under pressure to sterilize materials.

Bacterial endospores are killed at 15 psi, 121.5 degrees C for 30 minutes.

7. What is Pasteurization? What does it want to accomplish? What is the batchmethod?

Pasteurization is heating a beverage to a high temperature to accomplish the following:

 Kill all pathogens

 Reduce most spoilage microorganisms

 Not damage the product

Milk is pasteurized at 63 degrees C for 30 minutes in holding or batch method.

8. What are the two toughest milk-borne pathogens to kill by Pasteurization?

 Toughest milk-borne pathogens are Mycobacterium tuberculosis and Coxiella burnetii

9. How does refrigeration and freezing control microorganisms?

Cold temperature—inhibits growth

10. How does salting, desiccation, and canning preserve food?

Canning—sterilized food in sealed container

High osmotic pressure—removes water

11. What is lyophilization?

Freezing drying (lyophilization)—food is immersed in liquid nitrogen and vacuum removes water in the form of vapor

12. What are membrane filters? What are they used for?

Membrane filters are used to purify heat- sensitive liquids such as beverages, some microbiological media, pharmaceuticals, etc.

• Microbes are removed by a filter in filtration

13. What are HEPA filters? What are they used for? What are biological safety cabinets?

High-efficiency particulate air filters (HEPA) remove microbes, particulate pollutants, and spores from air; these filters are made of fibrous materials.

• Biological safety cabinets are used to safely handle higher level pathogens.

14. Distinguish between nonionizing radiation and ionizing radiation?

• Nonionizing radiation is electromagnetic energy that is not powerful enough to eject electrons. (UV light or germicidal lamp)

• Ionizing radiation is electromagnetic energy that is powerful enough to eject electrons, forming ions of various molecules in the cell. (x-rays and gamma rays)

15. How does ultraviolet light damage DNA? What is the use of this type of control?

Ultraviolet radiation causes disruptive pyrimidine dimers in the DNA, kinking the double helix and disrupting DNA replication. Commonly used in surgical rooms.

16. What is gamma irradiation? What is the use of this type of control?

Pasteurizing dose uses gamma irradiation to preserve, extend shelf life, and kill pathogens.

Gamma irradiation is a form of ionizing radiation

17. What is the difference between disinfectant and antiseptic?

 Disinfectant is a chemical substance that

reduces the number of microbes except

endospores. Disinfectants are used on

inanimate objects.

 Antiseptic is a chemical substance that

reduces the number of microbes on living

tissue like the skin or mucous membrane.

18. What factors affect the activity of an antimicrobial chemical substance?

The activity of an antimicrobial chemical substance is shaped by three major categories of factors: microbial characteristics, properties of the chemical agent, and environmental/host conditions.

19. What is the phenol coefficient?

Phenol coefficient is used to

measure the effectiveness of a

disinfectant or antiseptic.

20. What is the disc diffusion test?

Disk diffusion test

 Paper discs are impregnated with chemical

agent.

 Paper disc placed on plate, swabbed for a

lawn of bacteria.

 Plates incubated for 24 to 48 hours.

 Look for zones of inhibition.

21. What are these halogens used for? How do they kill microorganisms? a. Chlorine i. Gaseous ii. Sodium hypochlorite iii. Chloramines b. Iodine i. Tincture of iodine ii. Iodophores

 Halogens include fluorine, chlorine, bromine, and iodine.

 Halogen means “salt generating” when reacting with metals.

 Chlorine and iodine are the most important halogens for microbial control.

 Halogens are effective because they are oxidizing agents.

 Kill broad variety of microbes

Chlorine occurs in many forms:

 Gaseous

 Inorganic forms

 Organic forms

 Chlorine oxidizes and denatures proteins.

 Chlorine is used to treat drinking water to make it safe

Sodium hypochlorite in laundry bleach is used as a disinfectant.

Chloramines are organic chlorine- containing compounds used as microbicides and for making drinking water safe.

Iodine is larger and more reactive than chlorine.

Tincture of iodine is an antiseptic that is composed of 2% iodine in ethanol.

Iodophors are organic compounds that bear iodine, and release iodine slowly.

22. What is phenol? Who used it first as an antiseptic? How does it kill microorganisms? What are the disadvantages?

Phenol was first used by Joseph Lister in his antiseptic surgery.

 Hydroxylated aromatic ring

 Denature proteins

 Very toxic

 Caustic to skin in high concentrations

 Used more as a disinfectant today rather than antiseptic

Phenol denatures proteins and disrupts membranes.

23. What is chlorhexidine?

Chlorhexidine is used as surgical hand scrub, antiseptic, and mouth rinse for gum disease.

24. What is merbromin (mercurochrome) and thimersol (merthiolate)? What are they used for? How do they kill microorganism? Why were they banned?

Found in topical antiseptics like merbromin (Mercurochrome) and thimerosal (Merthiolate). These are

organic molecules that bear mercury.

Thimerosal was used as a vaccine preservative.

 Both were banned because of mercury content.

25. What is copper sulfate used for?

Copper sulfate used as algicide.

26. What was silver nitrate used for?

1% silver nitrate was used in the past to prevent acute hyperconjunctivitis caused by Neisseria gonorrhoeae

27. What are the two alcohols used as antiseptics? How do they kill microorganisms? Which is more effective in killing microorganisms, 70% or 95% alcohol?

Includes ethanol (ethyl alcohol) and isopropanol (isopropyl alcohol)

Used as antiseptics

 Popular in hand sanitizers

 70% alcohol is more effective than 95% alcohol in killing microbes.

 Alcohols coagulate proteins, disrupt membranes, and dehydrate cells.

28. What are soaps and how do they work?

Soaps are surfactants made from saponified lipids.

Since soaps have pH of 8.0, alkaline pH damages microbes.

29. What are surfactants?

Surfactants are substances that degerm by solubilizing particles clinging to surfaces by reducing surface tension

30. What are quaternary ammonium compounds? What are they used for? How do they kill microorganisms?

Quaternary ammonium compounds or quats contain nitrogen bound to four organic groups.

 Examples include benzakonium chloride in Zephiran and cetylpyridinium chloride in Cepacol.

 Used as antiseptics and disinfectant

31. What is hydrogen peroxide used for? What is benzoyl peroxide used for? How do they kill microorganisms?

Hydrogen peroxide (H2O2) is commonly used as an antiseptic and mouth rinse.

Benzoyl peroxide is found in over-the-counter acne medications.

32. What is formaldehyde used for? How does it kill microorganisms?

Formalin is aqueous formaldehyde solution. It is the most common aldehyde used.

 Disinfectant.

 Embalming fluid

 Inactivates viruses for vaccines

 Denatures microbial toxins to make toxoid vaccines

33. What is ethylene oxide used for? How does it kill microorganisms?

Ethylene oxide is a gas that denatures proteins and inactivates nucleic acids.

 Will kill vegetative cells and spores

 Toxic, carcinogenic, and explosive

 Mixed with Freon or carbon dioxide to make less explosive

 Used in “gas autoclaves”

 Sterilizes plastics that would melt in an autoclave, catheters, artificial heart valves, heart-lung machine components, and optical equipment

34. What is chlorine dioxide used for? How does it kill microorganisms?

What is the difference between genetic shift and a genetic drift.

• Genetic drift involves small point mutations in the viral genome due to replication errors.

• Genetic shift involves major changes in the influenza A virus due to genetic recombination.

What are the two rare complications you can get from influenza?

Two rare complications are associated with influenza infections:

Guillain-Barre syndrome causes damage to PNS, leading to muscle weakness and paralysis.

Reye syndrome is correlated with viral infection and aspirin use. Symptoms include nausea, vomiting, and progressive mental changes, leading to delirium. Syndrome affects brain and liver.