MLT 140 UNIT I: Intro to Microbiology

Vocabulary based flashcards covering the introductory concepts of microbiology, including branches of the field, terminology, equipment, microscopy, taxonomy, morphology, and growth requirements.

Bacteriology

The study of bacteria, which are prokaryotes that lack a nuclear membrane and a nucleus.

Mycology

The study of fungi, such as yeasts, which gain nutrients through absorption.

Parasitology

The study of parasites that gain nutrients from a host.

Virology

The study of viruses, which are the smallest infectious particles and require a host.

Epidemiology

The study of disease distribution.

Normal flora

Normal bacteria in the body that do not cause harm; common sites include the upper respiratory tract/mouth, GU tract/vagina, skin, and GI tract/intestine.

Pathogen

Microorganisms that cause disease, which can be categorized as true or opportunistic.

Opportunistic

Normally non-pathogenic organisms that cause disease if they are given the opportunity, such as in immunocompromised patients (infants and elderly). Ex. influenza

Commensal

A neutral relationship where the organism benefits but the host is not harmed. ex. proteus mirabillis.

Nosocomial

Infections that are acquired in a hospital setting. 5-6% hospital patients develop this. UTI most common. (caused by e. coli). Infection has to occur within 72 hours of hospital stay.

Iatrogenic

An infection that occurs as a direct result of a medical procedure. Ex. UTI from an indwelling catheter or infection from an incision during surgery.

Virulence

The ability of an organism to cause disease, also known as pathogenicity. Ex. shigella.

Aseptic techniques

Methods meaning "without sickness," including hand washing, avoiding aerosols, and using Biological Safety Cabinets.

Disinfectants

Chemical and physical methods used for the inactivation or inhibition of organisms, including some spores.

Sterilization

A process that removes or destroys all microorganisms.

Medium

Nutrients used for growing organisms; the plural form is media.

Incubator

An instrument used for cultivating media inoculated with organisms, most commonly set at $36^\circ \text{C}$.

Incinerator

A device used to "clean" metal loops before they are reused.

Ocular lens

The eyepiece of a microscope, typically providing $10\times$ magnification.

Rheostat

A brightness adjustment component that regulates light intensity in a microscope.

Condenser

A microscope component that focuses light onto the specimen.

Resolution

The detail maintained in a microscopic image.

Resolving power

The ability to delineate between two separate objects.

Parfocal

The ability to maintain focus when switching between different objective lenses.

Total Magnification

The product of the ocular lens magnification and the objective lens magnification ($\text{Ocular} \times \text{Objective}$).

Bright-field microscopy

The most common type of microscopy, characterized by a light background and dark objects.

Dark-field microscopy

Microscopy where the background is dark and the object is light.

Phase-Contrast microscopy

Microscopy where the background is gray and the object is light; used for observing clear objects in liquid, such as in urinalysis.

Taxonomy

The classification of organisms based on their relatedness.

A. Classification by Nomenclature: Taxa: Domain, kingdom, phylum, class, order, family, tribe, genus (organisms’ first name capitalized and italicized, e.g., Staphylococcus), species (last name, e.g., aureus), serological groups, strain.

B. Classification by Cellular Type: Eukaryotic (fungi), Prokaryotic (bacteria), Archaeobacteria (halophiles)

C. Classification by Cell Wall Characteristics: Gram-positive (purple), Gram-negative (pink)

D. Classification by DNA/RNA Relatedness

Gram-positive

Classification of bacteria that stain purple and have a cell wall containing peptidoglycan and techoic acid cross-links.

Gram-negative

Classification of bacteria that stain pink and have a cell wall containing peptidoglycan and lipopolysaccharides.

Cocci

Bacteria that have a round microscopic shape.

Bacilli

Bacteria that have a rod microscopic shape.

Vibrio (curved rod organism)

Spirillium (spiral shape, corkscrew)

Spirochetes (spirals like spring, more flexible)

Pleomorphic

Bacteria that exhibit variable microscopic shapes.

Crystal Violet

The primary stain used in the Gram's technique procedure.

Iodine

The mordant used in the Gram's technique to fix the primary stain.

Decolorizer

10 secs and rinse. will remove the crystal violet from the gram neg organisms because they have much thinner cell wall that will not hold the primary stain. gram pos are not as thin and will not be penetrated by the decolorizer.

Safranin

The secondary stain or counterstain used in the Gram's technique procedure. 30 secs. gram neg organisms take up the stain because their cell walls have high lipid content and a thinner peptidoglycan layer.

Capsule

A protective covering made of polysaccharides that acts as a virulence factor and appears as a "halo" on a Gram stain.

Results:

Positive (purple) - retains the primary stain, S aureus is the organisms that is usd as the control gram (+) orgs have cell walls made of peptidoglycan and acid cross links

Negative (pink) - retains the secondary stain, E. coli is the organism that is used as the control, gram(-) orgs have cell walls made of lipopolysaccharides and peptidoglycan

Variable (purple and pink) - some orgs are known as gram variable and you will see pink and purple on the slide

Capsule

covering that provides protection made of polysaccharides or other materials, “halo” seen on gram stain as it does not stain, virulence factor.

polysaccharides or polypeptides

provides defense against phagocytosis (virulence factor)

facilitates and maintains bacterial colonization of biologic and inanimate surfaces

Flagella

Exterior protein filaments that provide motility and act as a virulence factor.

monotrichous - singular at one pole

lophotrichou - two or more at one end

petritrichous - uniform distribution all over the body

amphitrichous - one flagella at each end

atrichous - absense, non motile bacteria

Pili

Non-motile, hair-like protein structures that connect cells and mediate DNA exchange.

Fimbriae

Sticky, hair-like appendages used for adherence to surfaces and other organisms. made of protein/

Spores

Specialized cells formed for survival under harsh conditions; they appear as unstained areas in a cell.

Growth Requirements

All bacteria have 3 major nutritional needs for growth: source of carbon, source of nitrogen, source of energy. Classified into 2 groups based on how these needs are met: autotroph or heterotroph

Autotroph

An organism that is a "self-feeder," meeting its own nutritional needs. tale inorganic co2 and convert it to organic compounds, not dependent on other living things for nutrition.

Heterotroph

An organism that obtains its carbon from other sources. all bacteria that inhabit the human body. more complex growth requirements, must get carbon from preformed organic matter such as glucose for energy.

Additional factors considered when bacteria cultured in lab:

B.  Water/moisture – so organism doesn’t dry out

C.  Inorganic salts:  regulate osmotic pressure

D.  pH:  optimal range 6.5-7.5

E.  Atmosphere: how they respond to O2, all require carbon, obligate aerobes, obligate anaerobes, aerotolerant anaerobes, facultative anaerobes, microaerophilic, capnophilic

F.  Temperature: thermophilic (heat), mesophilic (body temp), psychrophilic (cold)

G. Effects of neighboring organisms: symbiosis, parasitism, commensalism, antagonism, synergism

Obligate aerobes

require regular air with oxygen for growth

Obligate anaerobes

cannot grow in regular oxygenated air, require special growth environment without O2

Aerotolerant anaerobes

do not utilize O2 but can survive and grow to a limited extent in its presence, they are not harmed by O2 but do not use O2 for metabolism

Facultative anaerobes

do not require O2, though if present will use it and grow faster and better

Microaerophillic bacteria

can tolerate only very small amounts of O2 less than 5%

Capnophillic bacteria

require 5-10% CO2 for optimal growth

Thermophilic

Bacteria that require very hot heat for optimal growth. 50-60C or 122-140F

Mesophilic

Bacteria that grow best at body temperature. 20-40C or 68-104F

Psychrophilic

Bacteria that prefer cold temperatures for growth. 10-20C or 50-68F

Colonization

growth of microbiota in or on a body site without the production of damage of notable symptoms - normal flora - can change over time

symbiosis/mutualism

both orgs help each other working together to survive. Ex. lactobacillus in the urogenital tract prevents commensalism of pathogenic bacteria and they obtain nutrients that they need so this is a beneficial relationship for the organism and the host.

Parasitism

organism benefits at the expense of the host

Commensalism

organism benefits from the host without causing the host harm or without providing benefit to the host (flora in humans, kinda neutral)

antagonism

organisms are competing for the same nutrients in an environment, try to fight one another off so that they can take over,

Synergism

groups of organisms cooperate to produce a result that neither of them could carry out alone but this relationship is not necessary for their survival - they work together for the greater good but they dont really need the end result

Lag phase

A. The initial growth phase where bacteria ground themselves in the media.

Log phase

B. The growth phase where bacteria actively multiply. Binary fission. Will continue as long as orgs have nutrients and environment is favorable.

Stationary phase

C. The growth phase where nutrients become limited and viability decreases. Pollutants excreted by the bacteria begin to outnumber the bacteria.

Death/Decline phase

D. The final growth phase where nutrients are depleted and bacteria die.

Involution forms

Unexpected test results caused by antibiotics, inadequate growth requirements, or genetic alterations like plasmids and conjugation.

1.  Antibiotics - alter mechanisms for survival

  2.  Inadequate growth requirements - do not have all their growth requirements met, try to find ways to survive.

   3.  Genetic alterations: bacterial chromosomes mixed messages and cause mutations - plasmids (extra info on DNA which can be gained or lost, not essential for growth, antibiotic resistance genes), conjugation (transfer of genetic material from one bacteria to another, can pass on antibacterial resistance)

Collection of specimens

A. Before antimicrobials

B. Optimal site – affected area w/out surrounding site contamination

C. Optimal collection time - Obtain during stage of illness that the most organism would be present

D. Obtain sufficient quantity

E. Transport promptly and in container to maintain viability – culture should be setup w/in 2 hrs. if not properly preserved

F.  Obtain sufficient clinical information - site and time of collection, this will affects the type of organism you are looking for (normal flora vs pathogen) and what type of media you setup

G. Label properly – patient info & specimen site, time of collection

H. Sterile containers

Specimen Rejection

A. Wrong or no preservative/incorrect collection media used

B. Insufficient quantity

C. Not delivered to lab in timely manner

D. Contaminated specimen

E. Specimen not labeled properly

Anaerobic collection

must be in proper anaerobic collection/storage device and it must be from a site where anaerobes are not considered normal flora

Transporting specimens

Arrive at the lab within 30 mins of collection. If not then the specimen needs to be properly stored/preserved

Transport Containers – urine cup, sputum cup, stool container, blood cx bottle  

Cary-Blair

A type of holding or transport media used specifically for fecal specimens. for GI pathogens such sd salmonella

Stuart’s

gonococci, throat, vaginal wounds, skin swabs that contain fastidious organisms

Amies charcoal

modified from stuart’s original formula, charcoal helps eliminate metabolic products of bacterial growth

Pre-reduced media/anaerobic transport medium (ATM)

oxygen is removed from the media during processing to aid in the recovery of anaerobic organisms

Shipping

 Media  - classified by 3 properties

A. Physical state:

1.liquid (broth) – nutrients dissolved in water, bacterial growth indicated by change in appearance from clear to turbid

2.solid - most use agar as base (solidifying agent), derived from algae, is flexible & moldable, can add additional nutrients or inhibiting agents to grow/suppress particular orgs, heat agarose, adding supplements, pour into petri dish, allow to cool, becomes solid = agar plate

3. Chemical composition – we won’t get into this too much except when talking about specific orgs

Functional type: Non-selective/Supportive media

All-purpose media, such as BAP/SBA, that supports the growth of most non-fastidious microbes.

Selective media

Media containing chemicals, dyes, or antibiotics that inhibit certain organisms while supporting the growth of others, such as MAC or PEA or HEK or EMB. Helps with isolation and identification. EMB for gram neg. PEA and CNA used for gram pos.

Differential media

Media that allows the grouping of microbes based on visible characteristics, such as hemolysis on BAP/SBA or color changes as organisms utilize sugars. MAC, HEK, EMB, and XLD differentiate bacteria based on color changes in the media as the orgs utilize different sugars; XLD and HEK also differentiate H2S producers from non-producers by turning different colors.

Enriched media

Media with growth enhancers used for finicky (fastidious) bacteria, such as Chocolate Agar.

Enrichment broth

A broth that inhibits the growth of unwanted bacteria, often with antibiotics added to suppress normal flora.

Non-selective broth

supplement agar plates or when plating to plates is not possible

The oil immersion objective provides a total magnification of:

1000x when used with a 10x eyepiece.

The function of the ____ is to gather and focus light onto the specimen.

condenser lens.

List the four general sites of normal flora in the human body.

URT/Mouth, skin, GI tract, GU tract.

A(n) _________is a normally non-pathogenic organism that causes disease if

they are given the opportunity to do so, as in patients who are immuno-

compromise.

opportunistic pathogen

A(n) _______infection is acquired from a medical procedure or medication.

iatrogenic

A (n) ____is the apparatus in which media that have been inoculated with

microorganisms are cultivated at a constant temperature, typically at 36 degrees

Celsius.

incubator

The most common type of microscopy used in the clinical lab is:

bright field

Bacteria are classified as eukaryotic cells.

False; they are prokaryotic.

The cell walls of these organisms are made of a very thick protective

peptidoglycan (AA’S linked to sugars) layer with techoic acid cross-links:

Gram-positive organisms.

The organism’s first name, and it should be capitalized always and italicized

when in print:

Genus

List 4 types of sterilization.

incineration, moist heat, dry heat, filtration

Explain the difference between disinfection and sterilization.

Sterilization completely destroys all microbial life. Disinfection eliminates only a defined scope of microorganisms and does not destroy all of them.

What is the first test always performed to identify bacteria?

Gram stain:

a. Crystal Violet (primary stain)

   b. Iodine (mordant)

   c. Decolorizer

   d. Safranin (secondary stain)

What test distinguishes S. aureus from S. epidermidis?

What test distinguishes S. saprophyticus from S. epidermidis?

What reagent is used in the tube coagulase test?