Microbiology Quiz 1

steps involving the diagnosis of infectious diseases

1. patient with symptoms of disease consults clinician 2. clinician makes a preliminary diagnosis and writes orders for lab tests 3. appropriate specimen(s) collected and transferred to lab 4. specimen is examined macroscopically and microscopically 5. preliminary report 6. specimen is cultured and plates incubated 7. cultures are examined and tested 8. definitive report 9. Clinician interprets report and prescribes tx 10. patients outcome is monitored for success or failure

5 properties that distinguish viruses from living cells

1. they posses either DNA or RNA- living cells posses both 2. They are unable to replicate on their own 3. unlike cells, they do not divide by binary fission, mitosis, or meiosis 4. they lack the genes and enzymes necessary for energy production 5. they depend on the host cell ribosomes, enzymes and metabolities

temperate phages

DNA can remain integrated into bacterial chromosome generation after generation, may eventually be used to treat bacterial diseases

unique bacteria

Rickettsias, chlamydias, mycoplasmas are bacteria, but do not possess all the typical bacterial cells Rickettsias and chlamydia have gram negative type of cell wall and are obligate intracellular pathogens- must live within a host cell, cannot grow on artificial culture media) Rickettsias transmitted by arthropods

glycocalyx

a slimy gelatinous material produced by the cell membrane and secreted outside the cell wall (same bacteria) 2 types: slime layer and capsule

procaryotic cells

about 10 times smaller than eucaryotic cells simple compared to eucaryotic cells reproduce by binary fission cytoplasm not filled with internal membranes, is surrounded by a cell membrane, usually a cell wall and sometimes a capsule or a slime layer consist of a single, long, supercoiled, circular DNA molecule-serves as the control center of the cell plasmids ribosomes smaller than eucaryotic ones bacteria and archaea

biochemical and metabolic activities

as bacteria grow, they produce many waste products, some of which are enzymes pathogenic strains of many bacteria can be tentatively identified by the enzymes they secrete

animal viruses

can also attach to and invade cells with appropriate receptors (explains why some viruses only infect certain animals or regions of the body)

nutritional requirements of bacteria

carbon, hydrogen, oxygen, sulfur, phosphorus, and nitrogen some require special elements (calcium, iron, zinc) fastidious- picky, especially demanding nutritional requirements nutritional needs give clues to its identity

oncogenic viruses

cause specific types of cancer

living microbes

cellular microbes or microorganisms bacteria, archaea, some algae, protozoa, some fungi

virulence

degree to which a pathogen can cause disease

cell

fundamental unit of any living organism because it exhibits the basic characteristics of life

species

genus and the specific epithet

capsule

highly organized and firmly connected

motility

if a bacterium is able to "swim" usually due to flagella, less often axial filaments most spiral shaped bacteria and about 50% of bacilli are motile; cocci are generally nonmotile can be demonstrated by stabbing the bacteria into a tube of semisolid medium or by using the hanging-drop technique

two categories of disease

infectious diseases and microbial intoxications

pathogenicity

many pathogens are able to cause disease because they possess capsules, pili, or endotoxins, or because they secrete exotoxins and exoenzymes that damage cells and tissues tested by injecting the organism into mice or cell cultures

pleomorphic

no cell wall, can take different shapes

germination

return to vegetative state by first subjecting spore to a tx that weakens the spore coat (heat, extreme pH) and then having a nutritious environment (if no autoclave (pressure chamber), one may have to do this to destroy)

bacterial cell wall

rigid exterior that defines the shape of bacterial cells- chmically complex main constituent- peptidoglycan (only found in bacteria)

bacillus

rod

methanol-fixation

standardized technique, the preferred technique

biology

study of living organisms

Gram stain

the first way that a microbiologist will attempt to i.d a strain of bacteria even if can't id, will narrow down the options developed in 1884 by the Danish Dr. Hans Christian Gram

ribosomes

the sites of protein synthesis

protozoa

unicellular protists, eukaryotes move by pseudopods, flagella, cilia

metric system

used to express the sizes of microbes

latent virus infections

virus is able to hide from a host's immune system by entering cells and remaining dormant herpes viral infections are examples once aquired never completely go away

oncogenic viruses/ oncoviruses

viruses that cause cancer Examples- epstein-barr virus, human papillomaviruses, HTLV-1

bacteriophages

viruses that infect bacteria (phages) 2 categories: virulent bacteriophages and temperate bacteriophages

acellular microbes/ infectious particles

viruses, viroids, prions

bacilli

rods may occur singly, in pairs (diplobacilli), in chains (streptobacilli), in long filaments, or branched extremely short bacilli- coccobacilli

viroids

short fragments of single stranded RNA, which can interfere with the metabolism of plant cells transmitted between plants in the same manner as viruses

types of microscopes

simple compound electron atomic

staining procedures- 3 major catagories

simple stains structural staining procedures (capsule stains, spore stains, flagella stains) differential staining procedures (gram stain, acid-fast staining)

cocci

singly diplococci- pairs strepococci- chains staphylococci- clusters tetrads- packets of 4 octads- packets of 8

plasmids

small circular molecules of DNA that are not part of the chromosome (extra-chromosomal)

prions

small infectious proteins that causes fatal neurologic diseases in animals the most resistant to disinfectants the mechanism by which prions cause disease remains a mystery

viruses

small small (electron microscope) acellular particle containing either DNA or RNA can only reproduce by using the cellular machinery of other organisms, considered living when they infect infect humans, animals, plants, fungi, protozoa, algae, and bacterial cells

fluorescent microscopy

some organisms are able to absorb fluorescent dye and emit light when illuminated with uv rays also used to detect microbes by coupling a fluorescent dye to a specific antibody that will bind to the target (fluorescent antibody technique? immunofluorescence)

coccus

spherical or ovoid

Koch's postulates

steps that relate a specific microbe to a specific disease if an organism fulfills, it has been proven to be the cause of that particular infectious disease helped prove the germ theory of disease

microbiology

study of microbes, extremely small (microscopic) living organisms and certain non-living entities

classification

the arrangement of organisms into groups (known as taxa)

Phase-contrast microscopy

the best way to observe living matter- in its natural state and unstained since bacterua are almost transparent, they do not stand out under a normal light microscope

Human Immunodeficiency Virus (HIV)

the cause of acquired immunodeficiency syndrome (AIDS) enveloped, single-stranded RNA virus the primary targets= CD4 + cells (a type of T-Cell)

0.2mm

the resolving power of the unaided human eye is approximately

taxonomy

the science of classification of living organisms consists of classification, nomenclature, and identification based on the binomial system of nomenclature

pathogens

the scientific term for disease-causing microbes

generation time

time it takes for binary fission to occur varies from one species to another and depends on growth conditions

microbes

truly cellular (bacteria, archaea, algae, protozoa, fungi) + acellular (viruses, viroids, prions)

virus classification

type of genetic material (DNA or RNA) shape and size of capsid number of capsomeres presence or absence of an envelop type of host it infects disease it produces target cells immunologic/ antigenic properties

bacteria

unicellular procaryotes shape: bacillus, spiral, coccus enclosed in peptidoglycan cell wall many move using flagella

archaea

unicellular, prokaryotes, no peptidoglycan in cell wall found in extreme environments no pathogens

special structural stains

used to color and isolate specific parts of microorganisms negative staining for capsules- demonstrating the presence of a capsule is a means of determining the organisms virulence endospore (spore) staining flagella staining

colony morphology

a bacterial colony contains millions of organisms appearance of the colony varies from one species to another includes size, color, overall shape, elevation, ad the appearance of the edge or margin of the colony also includes the results of enzymatic activity on various types of media important clue to the identification of bacteria

spores (endospores)

a few genera (Bacillus and Clostridium) are capable of forming thick-walled spores as means of survival the process of formation is called sporulation been shown to survive for many years and are resistant to heat (survive boiling) cold, drying, and most chemicals

non-living microbes

acellular microbes or infectious particles viroids, prions, viruses

virulent bacteriophages

always cause what is known as the lytic cycle, which ends with the destruction of the bacterial cell

microscope

an optical instrument that is used to observe tiny objects, objects so small that they cannot be seen with the unaided eye

antiviral agents

antibiotics are not effective against viral infection antiviral agents are drugs that are used to treat virl infections interfere with virus-specific enzymes and virus production by disrupting critical phases in viral multiplication or inhibiting synthesis of viral DNA, RNA or proteins

atmospheric requirements

bacteria can be classified on the basis of their atmospheric requirements including their relationship to O2 and CO2 obligate aerobes microaerophilic aerobes facultative anaerobes aerotolerant anaerobes obligate anaerobes

fixation

bacterial smears must be fixed prior to staining the fixation process serves to kill organisms, preserve the morphology, and the anchors the smear to the slide two types of fixation- heat fixation, methanol-fixation

electron microscopes

better than compound microscopes, can magnify 2 million times enables us to see extremely small microbes like rabies and smallpox viruses living organisms cannot be observed using- the procedures kill the organism an electron beam is used as a source of illumination and magnets are used to focus the beam have a much higher resolving power than compound light microscopes 2 types- transmission and scanning (3D)

virions

complete virus particles, typically consists of a genome of either DNA or RNA surrounded by a capsid (protein coat) which is composed of protein units called capsomeres

eucaryotic cells

contain a "true" nucleus, possess membrane bound organelles, has a cell membrane some contain a cell wall some possess flagella or cilia algae, protozoa, fungi

compound microscope

contains more than one magnifying lens eyepiece/ ocular lens- X10 objective lens (X4,10,40,100) usually magnify objects about 1000X

4 categories of viruses, based on the type of nucleic acid that they possess

double-stranded DNA viruses single-stranded RNA viruses Single-stranded DNA viruses double-stranded RNA viruses

genetic engineering

gene or genes from one organism is/are inserted into a bacterial or yeast cell, the cell that receives the new genes is then capable of producing the gene products coded for by the new genes

Robert Koch

german physicist who made numerous contributions to microbiology made significant contributions to the germ theory of disease discovered that Bacillus anthracis produced spores developed methods of fixing and staining bacteria developed methods to cultivate bacteria discovered rod shaped bacteria in the blood of cattle boosted the development of microbiology by stressing laboratory culture and identification of microorganisms

bacteria divided into 3 major phenotypic categories

gram-negative and have a cell wall gram-positive and have a cell wall lack a cell wall (mycoplasma spp.)

pili (fimbriae)

hair like structures, most often observed on gram-negative bacteria composed of polymerized protein molecules called pilin are thinner than flagella, have a rigid structure and are not associated with motility enable bacteria to anchor themselves to surfaces some bacteria possess a sex pilus for conjugation

enveloped viruses

have an outer envelope composed of lipids and polysaccharides

Germ Theory of Disease

hypothesis that microorganisms cause disease- Pasteur

fungi

kingdom of unicellular or multicellular eukaryotes (unicellular yeasts, multicellular mold and mushrooms)

genetic composition

lab i.d of bacteria os moving toward analyzing the organisms DNA or RNA = molecular diagnostic procedures the composition os the genetic material (DNA) of an organism is unique to each species DNA probes make it possible to identify and isolate without relying on phenotypic characteristics

resolving power/ resolution

limit an optical instrument has to what can be seen using that instrument

slime layer

loosely connected to the cell wall

peptidoglycan

made up the cell wall of all types of bacteria some have a thick layer some have a thin layer and an outside layer of fats and sugars

dark microscopy

only the light that is reflected off the specimen enters the objective lens no background light very helpful to view microbes that are so thin and small that they approach the limit of L.M magnification

microbe uses

photosynthetic algae and bacteria (such as cyanobacteria) produce much of the oxygen in our atmosphere decomposition of dead organisms and waste various elemental cycles food for tiny animals- link in food chain live in intestinal tracts of animals, aid in digestion

algae

photosynthetic eukaryotes, unicellular or multicellular

gram negative

pink

Five kingdoms

procaryote (bacteria and archaea) Protista (algae and protozoa) fungi plants animals

cellular microbes (microorganisms)

procaryotic (bacteria and archaea) + eucaryotic (algae, protozoa, fungi)

gram positive

purple

sporulation

repackaging a copy of DNA in a new form that contains little water-not reproduction, process of spore formation

Anton van Leeuwenhoek

"Father of Microbiology" not a trained scientist, made many simple single-lens microscopes, observed "animalcules" (bacteria and protozoa)

morphology

3 basic categories of bacteria based on shape cocci (round) bacilli (rod shaped) curved and spiral-shaped bacteria

Louis Pasteur

French chemist made numerous contributions investigated different fermentation products showed yeasts fermented sugars to alcohol showed bacteria fermented sugars into vinegar (spoiled the wine) solution- heat the beer, wine, milk to kill most of bacteria= pasteurization germ theory of disease discovered life forms could exist without oxygen (anaerobes) developed several vaccines, including rabies and anthrax vaccines

simple staining

Step 1- prepare your specimen, usually the specimen will come in one of two format wither directly from the patient (urine, sputum, blood, CSF, joint fluid, etc.) or bacteria already grown on a special medium spread a thin film (smear) on a glass slide and then fix it to the slide Step 2- stain it Step 3- give time for stain to soak into the bacteria Step 4- wash it Step 5- dry it

binary fission

one cell splits in half to become two daughter cells- end with two identical cells before a procaryotic cell divides in half, the chromosome must be duplicated

opportunistic pathogens

microbes that can cause disease, but usually do not, can be thought of as microbes that are awaiting the opportunity to cause disease

germs

microbes that cause disease

nonpathogens

microbes that do not cause disease, the majority of microbes

indigenous microflora

microbes that live on and in our bodies

flagella

motile bacteria possesses, number and arrangement are characteristic of a particular species whiplike structure that allows the cell to move

heat-fixation

not a standardized technique, excess heat will distort bacterial morphology

multicellular animal parasites

not strictly microorganisms medically important eukaryotes microscopic during some stages of life cycle