Introduction to Microbiology

Introduction to Microbiology

• Microbiology is the study of microbes, both living and nonliving entities too small to see
• Microscopes are required to study microbes, which are virtually everywhere (ubiquitous)

Diseases Caused by Microbes

• Infectious diseases arise when a pathogen colonizes and causes disease, typically over 24 hours
• Microbial intoxication happens when someone ingests a toxin produced by a microbe, with effects appearing in less than 24 hours

Major Categories of Microbes

• Acellular microbes ("infectious particles") include viruses and prions
• Cellular microbes include bacteria, archaea, protozoa, algae, and fungi
• Non-pathogens are microbes that don't cause disease
• Only 3% of microbes are pathogenic, meaning most microbes are harmless

Opportunistic Pathogens

• Opportunistic pathogens colonize the body
• They await the opportunity to cause illness when the host is weakened or immunosuppressed

Indigenous Microbiota

• Indigenous microbiota (resident microbes) live on and within a person
• Indigenous microbiota are usually absent in:
  • Fetus (can acquire microbes during/after delivery)
  • Blood and lymph
  • Spinal fluid
  • Most internal tissues and organs

Transient Microbes

• Transient microbes are temporary residents in humans

Reasons for Transient Residency

• These microbes are washed away
• These microbes are unable to compete against resident microbes
• The microbes fail to survive the pH or acidic/alkaline levels
• The microbes are killed by substances produced by the resident microbiota
• The microbes are flushed away by bodily functions

Dysbiosis

• Dysbiosis is an imbalance between a host and its microorganisms due to destruction of resident flora
  • Example: Prolonged antibiotic therapy can destroy gut flora, leading to dysbiosis and increased susceptibility to infection

Skin Microbiota

• Skin has a diverse microbiome, that is primarily bacteria and fungi
• Most skin microbes are anaerobes, thriving in deeper layers, follicles, and glands
  • Common bacteria includes Staphylococcus and Propionibacterium (causes acne)
• Moisture, warmth, and hair stimulates growth

Ear and Eye Microbiota

• Middle and inner ear should be sterile
• Outer ear and auditory canal have similar microbes to the skin
• External eye is protected by tears, lysozyme, and antimicrobials

Respiratory Tract Microbiota

• Upper respiratory tract (URT) has a warm, moist environment with abundant, varied population
• Opportunistic pathogens commonly live in the URT
• Healthy carriers can harbor virulent pathogens
• Lower respiratory tract should be sterile

Oral Cavity Microbiota

• The oral cavity has numerous anaerobic and aerobic bacteria
• Bacteria can be isolated from the gumline, crevices in the teeth and crypts on the tonsils
• The bacteria found thrive in food particles with dead cells
• A-hemolytic streptococci are most commonly seen
  • Streptococcus mutans contributes to dental plaque

GIT Microbiota

• Stomach acidity and gastric enzymes prevent growth, except for H. pylori
  • H. pylori can cause ulcers and enter from unsanitary food
• Few microbes survive in the Duodenum because they are destroyed by bile
• Numerous microbes are in the jejunum and ileum

Colon Microbiota

• Colon is the dirtiest body part
• It holds maximum microorganisms in body that are opportunistic and anaerobic
  • Example: E. coli causes diarrheia and affects microbiota
• Many are removed through excrement

GUT Microbiota

• Kidneys, ureters and the urinary bladder are sterile
• Distal urethra and urethal opening harbors microbes (viruses, yeasts and bacteria)
• Reproductive systems are sterile, except for the Vagina. Which has microbiota based on the development of the vagina:
  • At puberty/post-menopause - it has alkaline secretion where coliform grows
  • In child bearing years it is acidic with a 4-5 ph level
    • Lactobacilli prevents bacterial vaginosis by producing lactic acid

Why Indigenous Microbiota are Beneficial

• They inhibit pathogens by using space, depleting nutrients, or secreting inhibitory materials
• Constant source of irritants and antigens stimulate the immune system
• Indigenous Microbiota helps synthesizing vitamin
• indigenous Microbiota becomes biotherapeutic agents (medicine(
  • Example: Bacillus clausilli

Importance of Microbes

• Microbes produces oxygen via photosynthesis
• Decomposes dead plants and animals
  • Srophytes helps decompose organisms/matter
• Bioremediation decomposed Industrial waste
• Microbial ecology converts toxic nitrogen
• Important link in the food chain
• Aids in digestion of high life forms
• Uses for industry for food and beverages
  • Example: bread etc
• Antibiotic production
  • Example: penicillin kills bacteria
• Genetic Engineering
• Cell models

Eukaryotes

• Most organism are multicellular
  • Eu means true & Kayro means Nucleus
• 10x lager then porkaryotes
• They have nucleus which is encolsed with DNA
  • Like Fungi, parasitic, plant etc

Parts of Eukaryotes

• Centric command of the Nucleus includes genetic substance

Cell membrane

• Separates cell from its surrounding, and regulates the passage in and out
  • A selectively permanent cell

Cytoplasm

• The area surrounding where the organells are with the liquid portion
  • Nucleus, membrane, and cytoplasm are present in any cell

ER Endoplasmic Reticulum

• Transport via convoluted membranes

Golgi Apparatus

• Packages protien from ER to export

Ribosomes

• Protien fromed by peptide bonds

Proxisomes

• Vesicles where h202 is broken by 'Catalase'
• Abundant in live and removes dangerous substance like alcohol

Mitochondia

• Powerhouse that product ATP (energy)

Plastids

• Only in plats, are chroplasts

Cytoskeleton

• Suprtthe frame and strengthens
  • Microctubles or flamemts

Cellwall

• gives rigid shape and protections
• Is less complicated
• Not in humans
  • Exmaple- Chitin in fungus and celulose in plant

Flagetta

• Whip structure helps motility

Clila

• Shorter for coordinated movement

Prokaryotes

• Unicellular organism
  • Pro before, kayro nucleus
• Smallee is size
• NO TRUE Nucleus no DNA (opposite to Eukarotes) Example: bacteria & Archea

Parts of prokaryotes

• Cytoplasm does the same function as eukaryotes

Cell Membrane

• Thin more flexible with mesosome
• Invagination, for ATR purposes

Chromosome

• Directs control via the DNA molecules outside the chromosomal dna

Plasmin

• Outer small doubkle strand
• Also called extra dna

Ribosmes

• Smaller and do the dame functions

Cell wall

• made of peptigolcan (murein) for sugar amuno acid bacteria
• Also helps defined the shape and gives strength Example -Thin- is positive -Thick is negative

Giycocalyx

• Geltanous and slimy on the outside of the bacteria

2 glycoalyx types

• Capsule and slime They differ in the following -Capsiles are rigid and firmly attached

-Slimes slide/ detach and provide hydration

Fibrae & Pili

• Made of protien smaller then flagella
  • Are made of PILIN
• Help attachment

Spores

• Dormant bacterial srrutcure from certain bacteria for survival by protecting copies of DNA with protein
• clostiridum causes tetanus
  • Created by heat, toxins dehydration
• Also resistnt, dromant

H D M Host Defense System

Host Defeense System is devided into these

• Non-specific- you are born with it
• Specific- Aquired

non specific Host

• Skin
  • Intact and unbroken Mucus

Chemical/Cell Factrs

• Dryin inhibits Bacteria Fatty acides are Antibacterial
• Perspiration and lusozomes removes things

Interfons

small virual for cells to produce

• Stops virus replicas

Non-Specific & Specific Imunniity

• Non specific (born with) is the 1St/2nd Line defense, Specfic is 3rd Lind

Microbiata Antagoizin

indeginouse prevent pathogenc establishment by making bacteria -E-CILI destroys stuff which blocks pathogens

2nd line defnse, Tramferrin

glycoprotein removes pathogens

fever

• Slows growth/ killas. but asop as possible
• pYROGENS cause fever body or out
  • Disadvantage- Non selective will hurt everyone
  • advantage helps fast

interferns

• interfere by replication, makes protiens

complement systems

3O protiens help with inflammation

• Opsonizing the proteins that finds and destorys,
• Easier access is provided

Cytokine

chem mediators release

inflammation

promote the help

3 major events of inflamation

• Vasodiation capillary permiability
• Accumlation of leucukcytes

Phatyosis

• ingest materials macrothrophils are used

step in phagocosis

• chemotaxis -phag attracted to ste Attach-phag will attaach
• Inge- the particals in

Humoral Immnity

Produce of antibodies

• major role

Cell

multicelular with many cells

Immunity

Resistance of diseas- aquired

Active Immmunnity- long lasing

natural, infection like

Pasive Immunity- shorter

-natural transfusion is artification

Vacccine

Anficially induce immity .STIMYRecipriants, sytems for antibodies -stim Recyprinats, Abs Memory

Ldeal

Enough Strains Side ffecrtes Diseases

Type vacccines

atten- not for imm comprs Ex- bcg 2 act- easirer not ffecrt EX dpt

CHAIN

Infected
Resivo Exit Trans Entry Hoost

• break via hand wash

Classify via Morh Staning motule

morthoc Shpae Cocci Bac

Gram Stain

thick is po thin ne note in all

Gram stain steps

Vilet ioodien alcool sofrain

Most cocci are POSITIVE for gram stain:

• neissera Bacilli are negative = Baccuilua

Basic concepts of communicable dz

• Puth- is dis. stud is pathy

2 prodromal

• feel off- is shory

3

symps

4 couvulecent

pt recver

• range of non spesic

Loc Vs System

locale is one sit

Virulent face

Receotrs adhesin mols that recon attacht

obla inter sell

• micro that grow/lyse ricckets fac int sell
• micro i both cell nerssia

capsula

• much cap= resis flagella
• enbl the body caviry

exoensim

• protiens destroy coaguse converb the the throm/ fibro

camfloj forieng n nature of the protein

molc mim ptn antog are resemb

antioboy

28)5m Pathogenesis inf dz

• entry= pathogen. attaches to tissue multipl the s

entry -injure + dam avai def break thw chain

viurule degre og d

fact that escape

Pathogens may land

Factors at a site antibt fac indegene food helth stus vaccine phato

Gram Stain

Positive is thick peptidoglycan cell wall and negative is thin peptidoglycan and

extremely important “clue” when attempting to learn the identity of the species

Types of staining

Crystal Violetbacteria absorbs dye, Iodine looks like betadine brownish in color leads to purple-brown

Decolorizationethanol or alcohol is applied gram positive will remain Gram will become transparent

Safraninapply pink stainbacteria becomes purple if see-through,itis Gram stains are pink, not purple

Gram Stain Notes

Most COCCI are Gram POSITIVE

Most Gram Gram NEGATIVE, and SPirochetes are Gram NEg

Gram stain motility:

whether a bacteria is motile or nonmotile acteria are classified based on motility

• = flagella or axial, Nonmotile = flagella, cocci usually in spirochetes and Bacillus

Atoms requirements

. relationship of can only grow are fac= favor for pos= like grape MR: not Aerobic= areobe revor=human Transmited by secretion + food

Gram stain- Virulence factor

• Single fla toxi - des struxtu

Diseases -Strep

burn wound, ears, tu=b fol

Transmited by Rea and trea by antib.

43-bacillus

Opper, Micioti

• indg = aid digest in, e colis hklps syn vtm k Trans
  Rever- human, conlon