OVERVIEW OF MICROBIOLOGY AND INTRODUCTION TO BACTERIOLOGYMICROBIOLOGY
Derived from 3 Greek words:MICROS small, minute or tiny
BIOS Life, livingLOGOS Science/ study
BASIC MICROBIOLOGY | BRANCHESBacteriology (bacteria)
Virology (virus)Parasitology (parasites)
Mycology (fungi)Protozoology (protozoan)
Phycology (algae)
APPLIED MICROBIOLOGYAgricultural Microbiology - Relationship of microbe to crops, and how to
increase crop productionFood and Dairy Microbiology - Studying the detrimental effects/ beneficial
effects of microbes in foods & drinksMicrobial Ecology - Study of microbes and its relationship to the
environmentImmunology
Molecular BiologyEARLY DEVELOPMENT - CONTRIBUTORS
Anton Van Leeuwenhoek - “animalcules”- Bacteria, Algae, Protozoans & yeast- Discovered the 3 forms of bacteria (rod,
spherical, spiral shape)
Robert Hooke - Confined Leeuwenhoek’s discovery using a compound microscope
Francisco Redi - Spontaneous theory did not apply to animals- Flies did not develop spontaneously from
putrefied meat (Putrefaction- decomposition of organic matter)
Lazaro Spallanzani - Contaminating air- Microorganisms in heated infusions in sealed
flasks showed no evidence of growth of microorganisms once the seal was broken, microbial growth was evident.
- Microorganisms did not spontaneously but came from CONTAMINATING AIR
Franz Schultze - Boiled infusions and admitted air passed through strong sulfuric acid. No growth of microorganism seen.
Theodore Schwann - Heated flasks containing infusions and allowed reheated air to enter the flasks.
- Unsealed flask showed no evidence of growth in the infusion no matter how long the allowed heated air to enter the flask.
- Microorganisms in the air were killed by heating and therefore no growth of microbes observed
Shroeder and Van Dusch - Cotton plugs can filter air thus preventing growth of microbes and boiled solutions
Loius Pasteur - Constructed a swan-neck flask demonstrating that air free of microbes could not create life in organic infusions.
- Conclusion: Microorganisms and not spontaneous generation were responsible for the growth in the flask.
- Pasteurization technique – killing of microorganisms by heat
RUZZO | Russcriptions
Robert Koch - 1 disease, 1 agent- Relationship between disease agent and a
specific disease conditionExamples:- Whooping cough is caused only by Pertussis- Etiologic agents of anthrax and tuberculosis
through his KOCH’S POSTULATEMODERN DEVELOPMENTS
Genetic EngineeringProduction of New Vaccines
Gene TherapyStem Cell Therapy
Continuous Discoveries of New Strains of OrganismsKOCH’S POSTULATE
1. A specific microbe can ALWAYS be found associated with a given DISEASE.2. The microbe can be ISOLATED and GROWN in pure culture in the laboratory.3. The pure culture of the microbe will produce the disease when injected into a susceptible HOST.4. It is possible to RECOVER the injected microbe from the experimentally infected animal.
MICROORGANISMS EXAMPLE GIVENACELLULAR VIRUSES
- Small infectious particles- Lack many attributes of cells- Replicates ONLY when it infects cells- Consists of NUCLEIC ACID molecule, either DNA/ RNA,
enclosed in a protein coat or capsid
Small poxVaricella
PRIONS- Proteinaceous and infectious particle, which may have
the same amino acid sequence of a normal but differs physically (due to FOLDING/ REFOLDING)
Creutzfeldt-Jacob diseaseKuru
CELLULARProkaryotes
BACTERIAARCHAEABACTERIA
Microbial EukaryotesPROTISTS
ALGAE- Organisms that
produce OXYGEN as a product of photosynthesis
- Contain chlorophyll- Unicellular/
multicellular organisms
Dinoflagellates – red tide- Gonyaulax sp.
RUZZO | Russcriptions
PROTOZOA- Unicellular non-
photosynthetic protists
Flagellates – flagella- Giardia lamblia- Trichomonas
vaginalisCiliates – cilia
- Balantidium coliAmoeba – pseudopodia
- Entamoeba histolytica
Sporozoa – immobile strictParasites
- Cryptosporidium sp.- Isospora beli
FUNGI- Non- photosynthetic
protists growing as a mass of branching interlacing filaments (hyphae) known as MYCELIUM
Major subdivision:
- Chytridiomycota- Zygomycota- Ascomycota- Basidiomycota- Deuteromycetes
SLIME MOLDS- Organisms that
contains PLASMODIUM (amoeboid multinucleate mass) as a stage in their life cycle
- Their growth depends on the nutrients provided by bacteria or plant cells
PROKARYOTES vs. EUKARYOTESCharacteristics Prokaryotes Eukaryotes
NucleusAbsent (NUCLEOID)
EXCEPT planctomycetesPresent
DNA structure
Present(Most with a SINGLE circular naked
strand with NO PROTEIN)EXCEPT:
- Vibrio cholera (2 circular)- Borrelia burgdoferi (linear)- Streptomyces coelicolor (linear)
Present(MULTIPLE chromosomes; protein
associated with DNA)
Organelles Absent Present(lysosomes, mitochondria, golgi body, ER)
RibosomesPresent
(Smaller, free in cytoplasm)
70s
Present(Larger bound to membrane)
80sCell Wall
Generally PresentComplex chemical composition
Present in some typesAbsent in others
Reproduction Binary Fission MitosisExample Bacteria Fungi, protozoa, algae, slime molds
RUZZO | Russcriptions
BACTERIAL SHAPE AND ARRANGEMENT
BACTERIAL STRUCTURE
GLYCOCALYX
- Synthesized substances surrounding cellCOMPOSITION
- Polysaccharide EXCEPT in Bacillus anthracis & Bacilus licheniformis (polymerized D- glutamic acid)
Polysaccharide layers:- CAPSULE – firmly attached, well defined layer- SLIME LAYER – loose
FUNCTION- Antiphagocytic increase invasiveness- Adherance (e.g. Streptococcus mutans – cause dental caries)
CELL MEMBRANE
- Multilayered structure external to cell membraneFUNCTION
- Provide structure, support, maintains shape- Osmotic protection- Anchors flagella- Serves as primer in cell division- Contributes to pathogenicity- Site of action of some antibiotics
RUZZO | Russcriptions
COMPOSITION- PEPTIDOGLYCAN (MUREIN, MUCOPEPTIDE)3 parts:- Has alternating N-ACETYLGLUCOSAMINE and N-ACETYLMURAMIC ACID (backbone)
- same in all species- Set of identical TETRAPEPTIDES side chains consisting of D- and L- amino acids
attached to NAM – vary in different species- Set of identical PEPTIDE CROSS BRIDGES – vary in different species- PENICILLIN: inhibit synthesis- LYSOZYME: can hydrolyze it
Tetrapeptide side chains:- L- alanine position 1 (attached to N-acetylmuramic acid)- D- glutamate position 2- D- alanine position 4- Position 3: most variable
- Gram (-): diaminopimelic acid - Gram (+): L- lysine
BACTERIA - GRAM STAINING- Classified as Gram (+)= PURPLE/BLUE or Gram (-)= RED/PINK- Gram staining procedure developed by HANS CHRISTIAN GRAM- Depends on ability of bacteria to retain the CRYSTAL VIOLET-IODINE COMPLEX
RUZZO | Russcriptions
GRAM POSITIVE GRAM NEGATIVE- Thicker peptidoglycan (40 sheets) - Thinner peptidoglycan (1-2 sheets)
TEICHOIC ACID and TECHURONIC ACIDS2 types:
1. Wall teichoic acid2. Membrane teichoic acid (or Lipoteichoic acid)
LIPOPROTEIN- Stabilize outer membrane & anchors it to
peptidoglycan
FUNCTION- Bears antigenic determinants- -Streptococcus pneumoeae (Forssman
antigen) -M. tuberculosis (tuberculin) -S. aureus (A protein) -S. pyrogenes (M protein)
OUTER MEMBRANE- Bilayered structure- Excludes hydrophilic & hydrophobic molecules
thereby protecting the cell from harmful substances
- Contains special channels: PORINS – passive diffusion of LMW hydrophilic compounds like sugar, ions
LIPOPOLYSACCHARIDE (LPS)- Endotoxin
Consists:1. Lipid A – toxic;2. O polysaccharide (O Antigen) – highly
immunogenic; function as antigen3. core polysaccharides – ketodeoxyoctanoic acid
(KDO) and heptosePERIPLASMIC SPACE
- space bet. The inner & outer membranes- contains peptidoglycan layer, binding proteins,
hydrolytic enzymes, detoxifying enzymes that neutrolyze/ inactivate certain antibiotics
ACID FAST CELL WALLS - contains mycolic acids- Mycobacterium tuberculosis
MYCOPLASMA
- Lack cell walls/ peptidoglycan- Wall less Archaea- Resistant to many drugs such as Penicillin and
Cephalosposporins- Mycoplasma pneumoniae
CELL MEMBRANE- “CYTOPLASMIC MEMBRANE”
COMPOSITION- Phospholipid bilayer and proteins- No sterols (EXCEPT for Mycoplasma)
FUNCTIONS- Selective barrier and active transport of solutes- Electron transport and oxidative phosphorylation in aerobic species- Excretion of hydrolytic co-enzymes- Bears enzymes and carrier molecules for biosynthesis of DNA, cell wall polymers & membrane lipids- Bears receptors and carrier molecules & other proteins of the chemotactic & other sensory transduction
system
FLAGELLA- Long filamentous thread- like appendages (12-30nm) composed of entirely protein- Made up several thousand molecules of a protein subunit called FLAGELLIN
FUNCTION- Motility- Bears H-antigen
THREE TYPES OF ARRANGEMENT
MONOTRICHOUS - Single polar flagellum
LOPHOTRICHOUS- Multiple polar flagella
PERITRICHOUS - Flagella distributed to the
RUZZO | Russcriptions
entire cell
FIMBRIAE/ PILI- Hair like filament- Shorter, straighter, thinner than flagella- Composed of structural protein subunits termed PILINS
FUNCTION- Attachment (ordinary pilus) role in the adherence of symbiotic & pathogenic bacteria to host cells- Reproduction (sex pilus) responsible for attachment of donor and recipient cells in bacterial
conjugation
CYTOPLASM- Composed of amorphous matrix
NUCLEOID - No true nucleus- COMPOSITION: DNA- FUNCTION: directs activity of cell
RIBOSOMES - 70s- FUNCTION: protein synthesis
INCLUSIONS/ GRANULES - Glycogen, lipids, phosphate- FUNCTION: storage for nutrients
-Metachromatic granues -Polysaccharide granules -Lipid inclusions -Sulfur granules
TAXONOMY- Science of classification- Naming of different forms of life according to the International code of principles, rules and
recommendations and the identification of unknown organismsTaxonomic Ranking
Kingdom Share 1 or few general characteristics (E. coli: Procaryotae)
Phylum ProteobacteriaClass GammaproteobacteriaOrder EnterobacterialesFamily EnterobacteriaceaGenus Escherichia
Species Organisms share majority of characteristics (Escherichia coli)
BERGY’s MANUAL OF SYSTEMATIC BACTERIOLOGYPHYLUM
CLASS ORDER IMPORTANT GENERA
PROTEOBACTERIAAlpha Proteobacteria
RickettsialesEhrlichiaRickettsia
Rhizobiales BartonellaBrucella
Beta proteobacteria Burkholderiales BordatellaNeisseriales Neisseria
Gamma Proteobacteria Thiotrichales FrancicellaLegionellales LegionellaPseudomonadales MoraxellaVibrionales Vibrio
RUZZO | Russcriptions
Enterobacteriales Citrobacter SalmonellaEnterobacter SerratiaEschirichia ShigellaKlebsiella YersiniaProteus
Pasteurellales Pasteurella HaemophillusEpsilon proteobacteria Camphylobacterales Campylobacter HelicobacterFirmicutes (Low G+C G(+) bacteria Clostridialles Clostridium
Mycoplasmatales Mycoplasma UreaplasmaBacillales Bacillus
ListeriaStaphylococcus
Lactobacillales Enterococcus StreptococcusLactobacillus
Actinobacteria (highG+C G(+) bacteria
Actinomycetalles ActinomycesCornebacteriumGardnerellaMycobacteriumNocardiaPropionobacteriumStreptomyces
BACTERIAL CLASSIFICATION
Gram (+) cocciStaphylococcus sp.Streptococcus sp.Enterocoocus sp.
Gram (-) cocci Neiserria sp.Veilonella
Gram (-) Facultative Anaerobic Bacteria
Escherichia sp.Klebsiella sp.
Salmonella sp.Shigella sp.Proteus sp.Yersinia sp.
Gram (-) Non-enteric bacilliVibrio sp.
Haemophilus sp.Pasteurella sp.
SCIENTIFIC NOMENCLATURE- All organisms have binomial names
Genus and Species- e.g. Escherichia coli E. coli
Escherichia coli E. coli
SPORULATIONSpore formation
Highly durable dehydrated resting cells
Survive extreme heat, lack of water, many toxic chemicals
Means of survival
1 spore from 1 vegetative cell
DIPICOLINIC ACID – in core
Location: central, terminal, subterminal
e.g. Bacillus; Clostridium
GERMINATIONEndospore can remain dormant for thousands of years
Favorable conditions
RUZZO | Russcriptions
Breakdown layers surrounding endosporeSTAGESACTIVATION
- agent that overcome its dormancy (heat, acidity)
INITIATION- water taken up & dipicolinic acid released
OUTGROWTH- emergence of new vegetative cell
NORMAL FLORA- microorganisms normally residing in a particularly body site- they do NOT cause infection in healthy humans
LOCATION IMPORTANT ORGANISM LESS IMPORTANT ORGANISMS
Skin
S. epidermidis S. aureusCorynebacterium diptheriaeVarious StreptococciPseudomonas aeruginosaYeast
NoseS. aureus S. epidermis
Corynebacterium diptheriaeVarious Streptococci
MouthS. viridans Various Streptococci
Eikenella corrodensDental Plaques Streptococci mutans Provetella intermedia
Throat
Streptococci viridans Various StreptococciNeisseriaH. influenzaS. epidermidis
Colon
Bacteroides fragilisE. coli
FusobacteriumLactobacillusEnterococcus faecalisEubacteriumClostridium
Vagina
LactobacillusE. coligroup B streptococci
Various StreptococciGram (-) rodsB. fragilisC. albicans
STERILE SITESBlood
Cerebrospinal fluid (CSF)Urinary BladderPericardial fluid
Synovial fluid
TRANSMISSION OF DISEASECONTACT TRANSMISSION
Direct transmission
- contact between the source and hostExample:
- hand-to-hand- STD- Bacterial & viral respiratory tract diseases- Kissing- congenital
Indirect Contact - from reservoir to susceptible host- by means of non-living objects
RUZZO | Russcriptions
Example- Fomites – inanimate objects
Droplet Transmission - Spread through droplet nuclei that travel through short distance
VEHICLE TRANSMISSION- Waterbourne, foodborne, airborne
VECTOR- Animal/ insects carry agents from host to another- Arthropods- Mechanical transmission (e.g. HOUSEFLY)- Biological transmission (e.g. MOSQUITO BITE)
DEFINITION OF TERMSNormal Flora - “normal microbiota”
- They are mixture of microorganisms usually found in body sites and DO NOT CAUSE ANY DISEASE
Nosocomial Infection - An infection that develops during a stay in the HOSPITAL and is usually unrelated to the primary condition
Community acquired infections
- An infection contracted outside of health care setting, usually community based, and are infection present on admission
Endogenous infection - Infection caused by a PATHOGEN from an individual’s OWN bodyExogenous infection - Infection caused by a PATHOGEN acquired acquired OUTSIDE of the body
that have gained access to the bodyColonization - The presence and multiplication of microorganisms without tissue invasion
or damageCarrier - Any person or animal that HARBORS a particular infectious agent without
discernable clinical disease and serves as a potential source of infectionParasitism - A symbiotic relationship where one organism, the parasite, lives in or on
another, depending on the latter for its survival and usually at the expense of the host.
- Ex. Entamoeba histolytica, which derives nutrition from the human host and causes amebic dysentery
Host - An organism infected by a pathogenMutualism - A symbiosis in which two organisms mutually BENEFIT from each other
- Ex. Termites and the flagellates, in their digestive system, which synthesize cellulose to aid in the breakdown of ingested woods
Commensalism - A symbiotic relationship in which two species live together and ONE species BENEFITS from the relationship without harming or benefiting the other
Virulence - The extent to which severe disease is produced in a population with clinically manifest disease
- Rabies= high virulentInvasiveness - The ability of microorganisms to ENTER the body and spread.Pathogenicity - The ability of microorganisms to produce clinically apparent illness in an
infected population- Measles= high pathogenicity
Toxigenicity - The ability the ability of microorganisms to produce TOXIN.Oppotunistic infection - An infection caused by normally nonpathogenic organisms in a host whose
resistance has been decreasedPathogen - A disease-causing microorganism.
MORPHOLOGIC DIFEERENCES AMONG THE BACTERIA
RUZZO | Russcriptions
Circular (Coccus) StreptococcusStaphylococcus
Neisseria
Rod (Bacillus)
CorynebacteriumListeriaBacillusClostridium
Mycobacterium (acid-fast)
ENTERICS: live in the GIT- Escherichia coli- Shigella- Salmonella- Yersinia- Klebsiella- Proteus- Enterobacter- Serratia- Vibrio- Camphylobacter- Helicobacter- Pseudomonas- Bacteroides (anaerobic)
HaemophilusBordetellaLegionellaYersiniaFrancisellaBrucellaPasteurellaGardnerella
Spiral
Spirochetes:- Treponema- Borrelia- Leptospira
Branching filamentous growth (like fungi)
Actinomycetes (anaerobic)Nocardia (partially acid-fast)
Pleomorphic ChlamydiaRickettsiae
No cell wall Mycoplasma
OXYGEN SPECTRUM
OBLIGATE AEROBES FACULTATIVE ANAEROBES
MICROAEROPHILIC OBLIGATE ANAEROBES
Gram (+)
NocardiaBacillus cereus
StaphylococcusBacillus anthracisCorynebacteriumListeriaActinomyces
Streptococcus Clostridium
Gram (-)
NeisseriaPseudomonasBordetellaLegionellaBrucella
Most other gram-negative rods
Spirochetes:- Treponema- Borrelia- Leptospira
Camphylobacter
Bacteroides
Acid-fastMycobacteriumNocardia
No cell wall Mycoplasma
RUZZO | Russcriptions
Top Related