Microbiology exam 3

Control of microbial growth

1. physical agents
2. chemical agents
3. mechanical means

Types of physical agents in control of microbial growth

1. heat (dry and moist)
2. radiation

Types of dry heat

1. dry oven
2. incineration

Types of moist heat

1. Non-pressurized
2. Pressurized

Examples of non-pressurized moist heat

1. hot water
2. boiling water
3. pasteurization

What are the 2 methods of pasteurization?

1. Batch method (LTHT)
2. Flash method (HTLT)

Flash method pasteurization

\- 75 degrees Celsius for 15 seconds

Batch method pasteurization

65 degrees Celsius for 30 mins

Pasteurization MUST

1. maintain taste
2. maintain nutritional value

Example of pressurized moist heat

Autoclave

Units of autoclave

\- Psi 15

\- Temp of 121 degrees Celsius

\- Time 10-40 mins

Types of radiation

1. ionizing
2. non-ionizing

Examples of ionizing radiation

1. X-ray
2. Cathode ray
3. Gamma-ray

Example of Non-ionizing radiation

UV Ray (thymine dimers)

What part of the body is microbe free?

All bodily fluids, tissues, and organs

Example of mechanical means to control microbial growth

filtration

HEPA filter stands for

High Efficiency Particulate Air

Nosocomial infections

Healthcare-associated infections, infection(s) acquired during the process of receiving health care that was not present during the time of admission.

What do you understand by drug susceptibility testing?

Testing is essential in those groups of bacteria commonly showing resistance

How are antibiotics produced?

Antibiotics are produced industrially by a process of fermentation

When do we use filtration to control microbes?

Filtration is used to sterilize heat-sensitive materials, such as culture media, enzymes, vaccines, and antibiotic solutions.

Which portal of entry is most used?

Typically a cutaneous or membranous route

What is oligodynamic action?

Small amount of heavy metal dust is used to destroy a wide range of microbes

Drugs are…

ideal, NOT perfect

what are Beta-lactam composed of?

1. Beta (B) lactam ring
2. Thiazolidine ring
3. Variable “R”

What is chemotherapy?

The use of chemical substances or drugs to treat or prevent disease

What is pasteurization?

Heat treatments of perishable fluids such as milk, fruit juices, or wine to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of survivors or germination of spores. It prevents infections and spoilage.

What are macrolides?

Any of a class of antibiotics containing a lactone ring, of which the first and best known is erythromycin.

What are aminoglycosides?

Inhibits protein synthesis

What are polymyxins?

A mixture of antibiotic polypeptides from Bacillus polymyxa that are particularly effective against gram-negative bacteria

What is superinfection?

An infection occurring during antimicrobic therapy that is caused by an overgrowth of drug-resistant microorganisms

What is therapeutic index?

The ratio of the toxic dose to the effective therapeutic dose that is used to assess the safety and reliability of the drug

Broad spectrum drugs

a class of antibiotics that act against an extensive range of disease-causing bacteria by targeting both gram-positive and gram-negative bacterial groups

Narrow spectrum drugs

target a few types of bacteria

Properties of drugs

1. Effectiveness
2. Safety
3. Selectivity

Microbicide

Kills microbes

Microbistatic

Inhibits microbe growth

Food irradiation

A food safety process that uses radiation to kill germs that can cause food poisoning (foodborne illness).

Chlorhexidine

A broad-spectrum antimicrobial biguanide used as a topical antiseptic and in dental practice for the treatment of inflammatory dental conditions caused by microorganisms

Stages of clinical infection

1. The incubation period
2. The prodromal stage
3. The period of invasion
4. The convalescent period

The incubation period

The period of time from the initial contact with an infectious agent to the appearance of the first symptoms

The prodromal stage

The earliest notable symptoms of infection appear as a vague feeling of discomfort, lasts about 1-2 days

Period of invasion

The period during a clinical infection when the infectious agent multiplies at high levels, exhibits its greatest toxicity, and becomes well established in the target tissue

The convalescent period

Patient begins responding to the infection, the symptoms decline and the patient’s strength and health gradually return

Microbiota

The native types of bacteria, fungi, and viruses that normally reside on the body

What is infection?

The entry, establishment, and multiplication of pathogenic organisms within a host

Thermal death time (TDT)

The least time required to kill all cells of a culture at a specified temperature

Sterilization

Any process that COMPLETELY removes or destroys all viable microorganisms

Initial colonization of the newborn

Rupturing of the amniotic sac exposes the baby to microbes carried by the mother.

Paba

is synthesized and utilized as a substrate for the synthesis of folic acid in many bacterial species, yeasts and plants

Salvarsan

a drug that was introduced at the beginning of the 1910s as the first effective treatment for syphilis, relapsing fever, and African trypanosomiasis

Halogens

A group of related chemicals with antimicrobial applications. most often used are chlorine and iodine

Tincture of iodine

Used as an antiseptic that can be applied on cuts, wounds, scratches, etc. It is also used to disinfect water from viruses and bacteria. Wounds can also be cleaned and disinfected by using the tincture of Iodine.

What are the 8 properties of drugs?

1. inhibit/destroy a wide range of microbes (Broad-spectrum)
2. prevent the development of antibiotic resistance
3. prevent the development of superinfection
4. soluble
5. not easily excreted
6. high concentration
7. available
8. affordable