Test 3

What is microbiology?

The study of very small living organisms (microorganisms or microbes) that are usually too small to be seen with the unaided eye.

What does the word "microbiology" literally mean?

Micro = very small (viewed with a microscope), bios = living organisms, logy = the study of.

How far back does microbiology date as a science?

Only about 200 years.

What was the belief about disease before the microscope was invented?

Disease was believed to be a punishment for crimes; villages became ill from "demons" appearing as foul odors from sewage/swamps (miasma theory).

What was the Black Death (The Plague)?

A pandemic caused by the bacterium Yersinia pestis, transmitted from rats to humans by fleas.

How many people died in the first Black Death pandemic?

(mid-500s A.D.): 40 million.

How many people died in the second Black Death pandemic?

(14th century): 25 million.

Where did the third Black Death pandemic spread?

(1860s): spread from China across Asia, Africa, Europe, and the Americas.

What happens to a flea infected with Yersinia pestis?

The bacteria multiply in the flea, blocking its digestive tract, causing the starving flea to jump to a new host (e.g., a human).

What are the symptoms of untreated plague?

Within a week: high fever, swollen lymph nodes (buboes), leading to intravascular coagulation and subcutaneous hemorrhaging (tissue death).

What is the mortality rate of untreated plague?

50-75%; death can occur less than one week after onset of symptoms.

What antibiotics are available to treat plague?

Streptomycin, gentamycin, tetracycline, and chloramphenicol.

How many cases of plague occur worldwide per year?

1,000-3,000 cases.

List three environmental impacts of microbes.

Maintain balance of life in oceans/lakes/rivers; convert nitrogen gas into organic compounds; break down wastes returning CO2; produce methane and ethanol; play a role in photosynthesis.

List four food products produced by microbes in the food industry.

Cheese, yoghurt, bread, alcoholic beverages.

What vitamins do microbes in human intestines produce?

Vitamin K (for blood clotting) and B vitamins (for metabolism).

What is a pathogenic microorganism?

A disease-producing microbe.

How many Hospital Acquired Infections (HAIs) occur each year in Canada, and how many deaths result?

220,000 HAIs result in 8,500-12,000 deaths annually.

What is the rate of hospital patients who get an HAI?

1 in 9 hospital patients.

Between 1995-2006, how much did the incidence of MRSA increase?

Increased 17-fold.

Between 1991-2003, how much did the number of patients contracting C. difficile increase?

Increased 5-fold.

What does MRSA stand for?

Methicillin-Resistant Staphylococcus aureus.

What infections can Staphylococcus aureus cause?

Pimples, pneumonia, food poisoning, wound infections.

How is MRSA spread?

By skin-to-skin contact.

What are the signs of a MRSA infection on the skin?

Red, swollen, painful; pus or fluid may drain.

Who is credited with discovering "cells" in 1665?

Robert Hooke.

What did Anton van Leeuwenhoek discover in 1673?

"Animalcules" (now known as bacteria and protozoa), found in rainwater, his own feces, and material scraped from his teeth.

What are the six categories of microorganisms?

Bacteria, Archaea, Fungi, Protozoa, Multicellular animal parasites (helminths), and Viruses.

What are the characteristics of bacteria?

Unicellular, prokaryotic (no nucleus), enclosed in cell walls composed of peptidoglycan, reproduce by binary fission, use organic chemicals for nutrition, some have flagella for swimming.

What are the three main groups of Archaea based on their environment?

Methanogens (produce methane), extreme halophiles (salty environments), and extreme thermophiles (hot sulfurous water).

Do Archaea cause disease in humans?

No, Archaea are not known to cause disease.

What are the characteristics of fungi?

Eukaryotic (have a nucleus), cell walls composed of chitin, absorb nutrients from environment, reproduce sexually or asexually; includes multicellular (mushrooms, molds) and unicellular (yeast) forms.

What are the characteristics of protozoa?

Unicellular eukaryotes, most are capable of locomotion (pseudopods, flagella, cilia), live as free entities or inside hosts where they can cause disease, reproduce sexually or asexually.

What are the characteristics of algae?

Unicellular or multicellular eukaryotes, cell walls contain cellulose, perform photosynthesis (produce oxygen and carbohydrates), reproduce sexually or asexually.

What are the two major classes of multicellular animal parasites (helminths)?

Flatworms and roundworms.

Are helminths strictly microorganisms?

No, only certain stages of their life cycle are microscopic.

What is the basic structure of a virus?

Very small (visible only with electron microscope), acellular, core made of either DNA or RNA (not both), core surrounded by a protein coat.

Are viruses considered living organisms?

Only when they multiply within a living host; they are inert (non-living) outside a living host.

What are the three domains of classification for microorganisms?

Bacteria, Archaea, and Eukarya (which includes protists, fungi, plants, and animals).

What is the correct format for writing a microorganism's scientific name?

First name (genus) capitalized, second name (species) not capitalized, both underlined or italicized. After first use, genus may be abbreviated (e.g., Staphylococcus aureus → S. aureus).

What did Francesco Redi demonstrate in 1668?

He challenged spontaneous generation by showing that maggots arise from flies, not from decaying corpses.

What did John Needham's experiment show in 1745?

Nutrient broth heated and then placed in a sealed flask still showed microbial growth (supporting spontaneous generation).

What did Rudolf Virchow claim in 1858?

Living cells can arise only from pre-existing living cells (biogenesis), challenging spontaneous generation.

What did Louis Pasteur's S-shaped flask experiment demonstrate in 1861?

Microorganisms can be present in nonliving matter, microbial life can be destroyed by heat, and methods can be devised to block access of airborne microorganisms.

What process did Pasteur discover that converts sugars to alcohol in the absence of air?

Fermentation (carried out by yeasts).

What is pasteurization?

Heating beer and wine just enough to kill bacteria, preventing spoilage.

What was the "miasma theory"?

The belief that disease was caused by "bad air" or foul odors from sewage and swamps, not by invisible microbes.

What observations did Ignaz Semmelweis make in the 1840s?

Childbed fever deaths were much higher in the division with doctors and medical students (600-800 deaths) than the division with midwives (60 deaths), because physicians didn't disinfect their hands.

What did Joseph Lister do in the 1860s?

Applied the Germ Theory to medical procedures, treating surgical wounds with phenol solution, greatly reducing infections and deaths.

What did Robert Koch discover in 1876?

The rod-shaped bacterium Bacillus anthracis, the cause of anthrax.

What did Edward Jenner discover in 1796?

Vaccination: infecting an 8-year-old boy with cowpox protected him from smallpox.

What is vaccination?

A process to protect from disease; protection from disease by vaccination or recovery is called immunity.

What is chemotherapy?

Treatment of disease by use of chemical substances; success depends on chemicals being more poisonous to microbes than to humans.

What are antibiotics?

Chemicals produced naturally by bacteria and fungi that act against other microorganisms.

What are synthetic drugs?

Chemotherapeutic agents prepared from chemicals in the laboratory.

What "magic bullet" did Paul Ehrlich discover in 1910?

Salvarsan, an effective treatment against syphilis.

How is syphilis treated today?

With the antibiotic penicillin.

What did Alexander Fleming discover in 1928?

Penicillin, by accident, when he noticed a clear area around mold (Penicillium) on a bacterial culture plate where bacteria did not grow.

In which domain does mold belong?

Eukarya.

List four problems with antibiotics and chemotherapeutic drugs.

1. Antimicrobial chemicals too harmful for host, 2. Toxicity in developing drugs for viral diseases, 3. Emergence of new strains, 4. Resistance.

What are the five branches of microbiology that emerged during the Golden Age (1857-1914)?

Bacteriology (bacteria), Mycology (fungi), Parasitology (parasites and protozoa), Virology (viruses), Immunology (immunity).

What is recombinant DNA technology?

Genetic modification of microorganisms to manufacture products they do not normally synthesize; involves inserting foreign DNA into bacteria.

What is gene therapy?

Inserting a missing gene or replacing a defective one in human cells, often using a harmless virus as a carrier.

What are the three examples of diseases treated with gene therapy?

Adenosine deaminase deficiency (ADA), Duchenne's Muscular Dystrophy, Cystic Fibrosis.

What is normal microbiota?

Microbes normally present in and on the human body that do no harm and can help prevent disease.

What is a biofilm?

A complex aggregation of microorganisms attached to a solid surface; can be beneficial (protect mucous membranes) or harmful (form on medical implants, often antibiotic-resistant).

What is an infectious disease?

A disease caused by an organism.

What is a communicable disease?

An infectious disease passed from one person to another.

What is a contagious disease?

A communicable disease easily transmitted from person to person.

What is a zoonotic disease?

A disease related to animals that act as a vehicle or vector.

What are three factors contributing to Emerging Infectious Diseases (EIDs)?

Evolutionary changes, spread of known disease to new geographic regions, antimicrobial resistance.

What is H1N1 influenza (swine flu)?

A virus first detected in the USA in April 2009; declared a global pandemic.

What is Avian influenza A (H5N1) (bird flu)?

A virus that killed millions of poultry and 24 people in 8 countries; sustained human-to-human transmission has not yet occurred.

What is West Nile encephalitis (WNE)?

Inflammation of the brain caused by West Nile virus; transmitted between birds and to horses/humans by mosquitoes.

What is Bovine Spongiform Encephalopathy (mad cow disease)?

A disease caused by an infectious protein called a prion.

What is Escherichia coli O157:H7?

A strain of E. coli associated with undercooked meat and unpasteurized beverages; leading cause of diarrhea worldwide.

What is Ebola Hemorrhagic Fever?

A disease caused by Ebola virus; causes fever, hemorrhaging, and blood clotting; epidemic controlled by introducing personal protective equipment.

What is the difference between immunity/resistance and susceptibility?

Immunity (resistance) is the ability to ward off disease; susceptibility is vulnerability or lack of immunity.

What are the two main types of immunity?

Innate immunity (nonspecific defenses) and adaptive immunity (specific defenses).

What are the characteristics of innate immunity?

Defenses present at birth, always present with rapid response, does not involve specific recognition of a microbe, does not have a memory response, includes first and second line defenses.

What are the characteristics of adaptive immunity?

Based on a specific response to a specific microbe after it has breached innate defenses, slower to respond, can remember past exposures (memory response).

What are Toll-like receptors (TLRs) and what do they do?

Protein receptors in the plasma membrane of defensive cells that attach to pathogen-associated molecular patterns (PAMPs); their interaction releases cytokines that regulate the intensity and duration of the immune response.

What are the two distinct portions of the skin?

Epidermis (outer, thinner) and dermis (inner, thicker connective tissue).

How does the skin act as a physical barrier?

Closely packed cells act as a barrier, shedding of top layer removes microbes, dryness inhibits growth.

What microbe is most likely to cause infection when the skin barrier is broken?

Staphylococcus aureus.

What are mucous membranes?

Epithelial layers with underlying connective tissue lining the gastrointestinal, respiratory, and genitourinary tracts that secrete mucus.

What is the function of mucus?

Inhibits entrance of microbes, prevents tracts from drying out, traps microorganisms.

What is the ciliary escalator?

Cilia on the lower respiratory tract beat to propel trapped mucus toward the throat, where it is swallowed or expelled.

What effect does cigarette smoke have on ciliary action?

Impairs ciliary action.

What is the lacrimal apparatus?

The eye protection system that manufactures and drains away tears; tears wash away microbes and contain lysozyme.

What is the function of saliva in innate immunity?

Cleansing action dilutes and washes away microbes from teeth and oral membranes, preventing colonization.

What are five other physical factors that provide first-line defense?

Epiglottis (prevents microbes entering lower respiratory tract), earwax (prevents entry into ear), urine (cleanses urethra), peristalsis/defecation/vomiting/diarrhea (expel microbes).

What is sebum?

An oily substance from sebaceous glands that forms a protective film on skin; unsaturated fatty acids inhibit growth of some pathogenic bacteria and fungi; contributes to low skin pH (3-5).

What is the function of perspiration in innate immunity?

Maintains body temperature, eliminates wastes, flushes microorganisms from skin surface, contains lysozyme.

What is lysozyme and where is it found?

An enzyme that breaks down bacterial cell walls by destroying peptidoglycan bonds; found in tears, saliva, nasal secretions, tissue fluids, and urine.

What antibody is found in saliva that prevents attachment of microbes to mucous membranes?

IgA (immunoglobulin A).

How does gastric juice provide defense?

Hydrochloric acid destroys bacteria and most toxins.

What bacteria can survive gastric acidity?

Clostridium botulinum, Staphylococcus aureus, and Helicobacter pylori (which neutralizes acid).

What is microbial antagonism?

Competition between normal microbiota and pathogens for nutrients and space, preventing overgrowth of pathogens.

What are bacteriocins?

Substances released by normal microbiota that are harmful to pathogens.