Microbiology Exam III

Chapters 9-12

Sepsis

refers to microbial contamination

Asepsis

is the absence of significant contamination

Aseptic Surgery

techniques prevent microbial contamination of wounds: (Boric acid, isopropyl alcohol, hydrogen peroxide, iodine)

Sterilization

Removing all microbial life: (Pressurized steam autoclave, chemicals, radiation)

Commercial Sterilization

Killing Clostridium Botulinum endospores

Disinfection

Removing pathogens: (Chlorine bleach, phenols, glutaraldehyde)

Anti-spesis

disinfection of living tissue

Degerming

Removing microbes from a limited area like the skin through hand washing: (Soap, alcohol swab)

Sanitazation

Lowering microbial counts on eating utensils and objects used in restaurants: (Detergents containing phosphates, industrial strength cleaners)

Biocide/Germicide

Kills microbes

Bacteriostasis

Inhibiting, not killing

Effectiveness of Treatment

Depends on

• Number of microbes

• Environment

• Time of exposure

• Microbial characteristics

Actions of Microbial Control Agents

• Alteration of membrane permeability

• Damage to proteins

• Damage to nucleic acids

Targets Cell Wall

Chemical, Detergents, Alcohol

Targets Cell Membrane

Detergents

Targets Cellular Synthesis

Formaldehyde, Radiation, Ethylene oxide

Targets Proteins

Moist heat, Alcohol, Phenolics

What is the most common physical control methods? What is destroyed?

Heat; Proteins and nucleic acids are destroyed. Water is removed

Thermal Death Point (TDP)

Lowest temperature at which all cells in a culture are killed in 10 mins

Thermal Death Time (TDT)

Time during which all cells in a culture are killed at a particular temperature

What does moist heat do to proteins?

Dentures proteins

What is Autoclave?

Steam under pressure

What does pasteurization do? What is NOT affected by pasteurization?

Reduces spoilage organisms and pathogens.

Bacterial Spores are NOT affected by pasteurization

High-Temperature Short Time (HTST)

72 C for 15 secs then bottled and refigerated

Ultra-High Temperature (UHT)

140 C for <1sec then sealed in airtight containers for up to 90 days without refrigeration

Dry Heat Sterilization

Kills by oxidation

• Dry Heat

• Flaming

• Incineration

• Hot-air sterilization

Other Physical Methods of Control

Low temperature lower microbial metabolic and growth rates, retarding spoilage

• Refrigeration

• Deep-freezing

• Lyophilization

What is Desiccation?

Prevents metabolism- Drying removes the water necessary for microbes to live

What does Osmotic Pressure cause?

Plasmolysis- Salting causes water to diffuse out of organisms, causing dehydration and death

What is radiation used for?

Is used to control microbes in food. This affects metabolism and physiology

Factors Affecting the Germicidal Activity of Chemicals

• Nature of the microorganisms being treated

• Nature of the material being treated

• Degree of contamination

• Time of exposure

• Strength of chemical action of the germicide

What is does the Disk-Diffusion Method measure?

Concentration and Chemical

• Lowest concentration- minimizes resistance dangerous to inhale respiratory damage

What does Chlorine do?

Keeps bacterial populations low in municipal water supplies and swimming pools

What does Iodine used for?

Is used to disinfect wounds, water, and restaurant equipment

What does Phenol and Phenolic Compounds do?

Denature proteins

Mercury, copper, and silver does what?

React with proteins

What is Silver sulfadiazine used for?

Topical cream on burns

What is Copper Sulfate?

An Algicide

What is ethanol effective against?

Vegetative cells but NOT endospores

Membrane disruption is caused by what?

Lipid Dissolution

How does soap remove microbes?

By emulsifying and solubilizing particles on the skin

Detergents are classified as…

Surfactants

What do detergents cause?

Cause cytoplasm leakage from microbial membranes

Organic Acids

• Inhibit metabolism

• Sorbic acid, benzoic acid, and calcium phosphate

• Control molds and bacteria in foods and cosmetics

What does Nitrate do?

Endospore germination

What antibiotics prevent spoilage of cheese?

Nisin and Natamycin

Chemotherapeutic Drug

Any chemical used in the treatment, relief or prophylaxis of a disease

Prophylaxis

Use of a drug to prevent imminent infection of a person at risk

Antibiotics

Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms

Synthetic Drugs

Drugs produced entirely by chemical reactions

Prontosil

Was a red dye found to inhibit some gram-positive bacterial species

Who originated the concept of selective toxicity?

Paul Ehrlich

What does selective toxicity mean?

That a drug should harm the pathogen but not the host

Chemotherapeutic index Equation

Toxic dose / Therapeutic dose

What does the Kirby Bauer measure (works best on bacterium)?

It tests if bacteria is susceptible to antibiotics (If it does, the antibiotic works). Depending on the diameter is big, the antibiotic works.

What is the E test?

A way to determine antimicrobial sensitivity by placing a stripe impregnated with antimicrobials onto the agar plate

What is MIC?

Minimum inhibitory concentration: the smallest concentration (highest dilution) of drug that visible inhibits growth

Modes of Action for Antibacterial Drugs

1. Inhibition of cell wall synthesis: Penicillin, Cephalosporins, Bacitracin, Vancomycin

2. Inhibition of protein synthesis: Chloramphenicol, erythromycin, tetracyclines, streptomycin

3. Inhibition of nucleic acid replication and transcription: Quinolones, Rifampin

4. Injury to plasma membrane: Polymyxin B

5. Inhibition of synthesis of essential metabolites: Sulfanilamide, Trimethoprim

What does Ampicillin inhibit?

Peptidoglycan

What antibiotic kills by halting translation?

Tetracyclines

• Selectively and action based on ribosomal differences between prokaryotes and eukaryotes

• Some toxicity

What antibiotic interferes with RNA synthesis?

Rifampin

• Effective against TB, leprosy, meningitis

• Cause liver damage

What is the order of antibiotic resistance?

1. Mutation

2. Exposure

3. Antibiotic Resistance

Unnecessarily large antibiotic doses allow resistant strains to ______ susceptible ones

overgrow

If resistant strains spread to other patients, a ________ occurs

Superinfection

Antibiotic use is widespread in ______ feeds

livestock

Bacterial cells can pass _______ genes to other bacterial cells

resistance

Mechanisms of resistance

1. Antibiotic inactivation

2. Active export of antibiotic (spits it out)

3. Altered metabolic pathway

Several classes of anti-fungal drugs cause ______ damage, causing contents to leak out

membrane

What is Nystatin (topical cream) used against?

Candida albicans infections in the intestines or vagina

What is Amphotericin (oral) used against?

Is used against serious systemic fungal infections

What is the goal of anti-protozoal agents?

Eradicate the parasite

What is Aminoquinolines (Quinine) used for?

Are anti-malarial drugs that accumulate in parasitized red blood cells

• They interfere with the parasite’s ability to break down and digest hemoglobin

Nitroimidazoles interfere with ___ ______

DNA Synthesis

• They are used to treat amoebiasis, giardiasis, trichomoniasis

A derivative of ______ is used against African trypanosomiasis

Arsenic

Anti-helminthic Agents are…

Praziqyantel

It changes membrane permeability in cestodes and trematodes

Ivermectins: causes contraction and paralysis in the parasite

Pathology

Study of disease

Etiology

The study of the cause of a disease

Pathogenesis

The development of disease

Infection

The successful colonization of the body by pathogens

Disease

Any condition in which the normal structure or functions of the body are damaged or impaired

Transient microbiota

may be present for days, weeks, or months

Normal microbiota

permanently colonize the host

Symbiosis

is the relationship between normal microbiota and the host

Microbial antagonism

is a competition between microbes

Normal microbiota

protect the host by

• Occupying niches that pathogens might occupy

• Producing acids

• Producing bacteriocins

Symptom

A subjective change in body function that is felt by a patient as a result of disease

Sign

An objective and measurable change in body function as the result of a disease

Syndrome

A specific group of signs and symptoms that accompany a disease

Communicable disease

A disease that is spread from one host to another

Contagious disease

A disease that is easily spread from one host to another

Latrogenic Disease

contracted as the result of a medical procedure

Non-communicable disease

A disease that is not transmitted from one host to another

Virulence factors

• Mycolic acid; fast-acid

• Filaments

• Spikes

True pathogens

Capable of causing disease in healthy persons with normal immune defense

Opportunistic pathogens

Cause disease when the host’s defenses are compromised

Endemic Disease

Disease constantly present in a population

Epidemic Disease

Disease acquired by many hosts in a given area in a short time. Ex: Flu epidemic in Florida

Pandemic

World-wide epidemic

Herd Immunity

Immunity in most of a population