History & Bacterial Classification - WordPress.com · BACTERIAL CLASSIFICATION ... characteristics used to define sections are ... Gracilicutes (thin skin)-Gram-negative Class Firmicutes

PHARMACEUTICAL MICROBIOLOGYPHARMACEUTICAL MICROBIOLOGY

JIGAR SHAHJIGAR SHAH

INSTITUTE OF PHARMACYINSTITUTE OF PHARMACYNIRMA UNIVERSITYNIRMA UNIVERSITY

History & Scope of MicrobiologyHistory & Scope of Microbiology

��WhatWhat isis Microbiology?Microbiology?

��StudyStudy ofof livingliving organismsorganisms ofof microscopicmicroscopic size,size, includeincludeBACTERIA,BACTERIA, FUNGI,FUNGI, ALGAE,ALGAE, PROTOZOAPROTOZOA && thetheinfectiousinfectious agentsagents calledcalled VIRUSESVIRUSES..

��StudyStudy ofof theirtheir form,form, structure,structure, generation,generation, reproduction,reproduction,physiology,physiology,metabolismmetabolism&& classificationclassification..physiology,physiology,metabolismmetabolism&& classificationclassification..

��StudyStudy ofof theirtheir distributiondistribution inin nature,nature, theirtheir relationshiprelationship toto eacheachotherother && toto otherother livingliving organisms,organisms, theirtheir effecteffect onon humanhumanbeingsbeings && onon otherother animalsanimals && plantsplants..

��TheirTheir abilitiesabilities toto makemake physicalphysical && chemicalchemical changeschanges inin ourourenvironmentenvironment..

��MicroorganismsMicroorganisms areare associatedassociated withwith healthhealth && welfarewelfare ofofhumanhuman beingsbeings

HISTORYHISTORY

•• BeforeBefore microorganismsmicroorganisms werewere discovered,discovered, somesomeinvestigatorsinvestigators likelike Bacon,Bacon, FracstoroFracstoro,, LucretiusLucretius suggestedsuggestedthatthat diseasedisease waswas causedcaused byby invisibleinvisible livingliving creaturescreatures..ButBut therethere waswas nono proofproof..

•• InIn 16581658,, KircherKircher waswas firstfirst personperson toto recognizerecognizesignificancesignificance ofof thesethese livingliving creaturescreaturesinin diseasediseasebybysignificancesignificance ofof thesethese livingliving creaturescreaturesinin diseasediseasebybyreferringreferring themthem inin decayingdecaying bodies,bodies, meat,meat, milkmilk &&diarrhoealdiarrhoeal reactionsreactions..

•• However,However, thethe firstfirst personperson toto observeobserve && describedescribemicroorganismsmicroorganisms accuratelyaccurately waswas VanVan LeeuwenhoekLeeuwenhoek inin16731673.. HeHe sentsent detaileddetailed lettersletters describingdescribing hishis discoveriesdiscoveriestoto thethe RoyalRoyal SocietySociety ofof LondonLondon.. ItIt waswas clearclear thatthat hehe sawsawbothboth bacteriabacteria && protozoaprotozoa..

HISTORY…HISTORY…

o After van leeuwenhoek discovered thepreviously “invisible” world of microorganisms,the scientific community of the time becameinterested in origins of these tiny living things.

o Upto the second half of the nineteenth century, manyscientists and philosophers believed that some forms oflife could arise spontaneously from nonliving matter.

o They called this hypothetical processSpontaneousGeneration.

HISTORY…HISTORY…

o The issue of spontaneous generation was resolved by French Scientist Louis Pasteur in 1861.

o With a series of ingenious and persuasive experiments, Pasteur demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but air itself the air and can contaminate sterile solutions, but air itself does not create microbes.

o Pasteur’s views are 1) m.orgs can be present in non living matter, 2) microbial life can be destroyed by heat, 3) methods can be devised to block the access of airborne m.orgs. To nutrient environments.

HISTORY…HISTORY…

�� Important events in Development of Microbiology.Important events in Development of Microbiology.•• 1786 1786 –– Muller produces first classification of bacteriaMuller produces first classification of bacteria•• 1798 1798 –– Jenner introduces cowpox vaccination for Jenner introduces cowpox vaccination for

smallpoxsmallpox•• 1857 1857 –– Pasteur shows that lactic acid fermentation is due Pasteur shows that lactic acid fermentation is due

to a microorganismto a microorganismto a microorganismto a microorganism•• 1869 1869 –– Miescher discovers nucleic acidsMiescher discovers nucleic acids•• 1876 1876 –– Koch demonstrates that anthrax is caused by Koch demonstrates that anthrax is caused by

Bacillus anthracisBacillus anthracis•• 1880 1880 –– Laveran discovers plasmodium, the cause of Laveran discovers plasmodium, the cause of

malaria.malaria.and so on………till the date…………in future…………and so on………till the date…………in future…………

SCOPESCOPE•• We live in age of Bacteria We live in age of Bacteria –– firstfirst livingliving organismsorganisms onon ourour planetplanet-- livelive virtuallyvirtually everywhereeverywhere lifelife isis possiblepossible-- moremore numerous,numerous,-- ConstituteConstitute largestlargest componentcomponent ofof earth’searth’s biomassbiomass-- WholeWholeecosystemecosystemdependsdependsonontheirtheiractivitiesactivities-- WholeWholeecosystemecosystemdependsdependsonontheirtheiractivitiesactivities-- InfluenceInfluence humanhuman societysociety inin countlesscountless waysways-- MicrobiologyMicrobiology hashas aa greatgreat impactimpact onon fieldsfields suchsuch asas

medicine,medicine, agriculturalagricultural && foodfood sciences,sciences, ecology,ecology,genetics,genetics, biochemistrybiochemistry && MolecularMolecular biologybiology..

So MODERN MICROBIOLOGY is large discipline with So MODERN MICROBIOLOGY is large discipline with many different specialities.many different specialities.

SCOPE…SCOPE…��MicrobiologyMicrobiology hashas beenbeen contributorcontributor toto thethe riserise ofof

MolecularMolecular BiologyBiology –– BranchBranch ofof BiologyBiology dealingdealing withwithphysicalphysical chemicalchemical aspectsaspects ofof livingliving mattermatter && itsitsfunctionfunction..

��MicrobiologistsMicrobiologists involvedinvolved inin studystudy ofof geneticgenetic codecode &&mechanismmechanism ofof DNA,DNA, RNARNA && proteinprotein synthesis,synthesis,recombinantrecombinantDNADNA technologytechnology&& geneticgeneticengineeringengineering..recombinantrecombinantDNADNA technologytechnology&& geneticgeneticengineeringengineering..

��SomeSome microbiologistsmicrobiologists focusfocus onon specificspecific groupgroup ofofmicroorganismsmicroorganisms::

VirologistsVirologists onon virusesviruses;; mycologistsmycologists onon fungifungi;;bacteriologistsbacteriologists onon bacteriabacteria;; protozoologistsprotozoologists onon protozoaprotozoa;;algologistsalgologists onon algaealgae..

SCOPE…SCOPE…��SomeSome workwork onon microbialmicrobial cytology,cytology, microbialmicrobial physiology,physiology,

microbialmicrobial ecology,ecology, microbialmicrobial genetics,genetics, microbialmicrobialtaxonomy,taxonomy, molecularmolecular biologybiology..

��SomeSome workwork onon medicalmedical microbiologymicrobiology (human(human && animalanimaldiseasedisease study),study), foodfood && dairydairy microbiology,microbiology, publicpublic healthhealthmicrobiologymicrobiology (communicable(communicable diseases)diseases)..

��ImmunologyImmunology –– ImmuneImmune systemsystem againstagainst pathogenspathogens-- FastestFastestgrowinggrowingareaareainin sciencescience-- FastestFastestgrowinggrowingareaareainin sciencescience-- EE..gg.. productionproduction andand useuse ofof monoclonalmonoclonal antibodiesantibodies��AgriculturalAgricultural MicrobiologyMicrobiology –– ImpactImpact ofof organismsorganisms onon

agriculture,agriculture, combatcombat plantplant diseases,diseases, toto increaseincrease soilsoilfertility,fertility, cropcrop yieldsyields

��Microbial ecology Microbial ecology –– Relationship between organisms & Relationship between organisms & their living/nonliving habitats. Their contribution to C,N their living/nonliving habitats. Their contribution to C,N & S cycles in soil & freshwater. Study of pollution& S cycles in soil & freshwater. Study of pollution

FUTUREFUTURE��MicrobiologistsMicrobiologists havehave toto workwork againstagainst widespreadwidespread &&

destructivedestructive newnew && oldold infectiousinfectious diseasedisease likelike AIDS,AIDS,SARS,SARS, TuberculosisTuberculosis..

��ToTo findfind waysways toto stopstop spreadspread ofof establishedestablished infectiousinfectiousdiseases,diseases, DiscoverDiscover ofof newnew drugs,drugs, newnew vaccines,vaccines, useuse ofofrecombinantrecombinant DNADNA technology,technology, molecularmolecular biologybiology

��MM..organismsorganisms importantimportant inin industryindustry && environmentalenvironmentalcontrolcontrol likelike sometimessometimesserveserveasassourcessourcesofof highhigh qualityqualitycontrolcontrol likelike sometimessometimesserveserveasassourcessourcesofof highhigh qualityqualityfood,food, theirtheir enzymesenzymes forfor industrialindustrial applicationsapplications andandincreaseincrease agriculturalagricultural productivityproductivity..

��ToTo studystudy ofof genomegenome sequence,sequence, genomegenome relationrelation toto cellcellstructure,structure, analysisanalysis ofof genomegenome forfor advancesadvances ininbioinformaticsbioinformatics..

��UnderstandingUnderstanding ofof microorganismsmicroorganisms helphelp moremore effectivelyeffectivelyinin controlcontrol ofof pollutionpollution

BACTERIABACTERIA

��“Bacteria”“Bacteria” isis aa pluralplural wordword.. TheThe singularsingular forfor thisthis wordword isis

“bacterium”“bacterium” ((bacterbacter == rod,rod, staff)staff)..

��BacteriaBacteria areare prokaryotesprokaryotes (Kingdom(Kingdom Monera),Monera), whichwhich meansmeans thatthattheythey havehave nono truetrue nucleusnucleus..

��TheyThey dodo havehave oneone chromosomechromosome ofof doubledouble--strandedstranded DNADNA inin aa ringring..

TheyTheyreproducereproducebybybinarybinaryfissionfission..TheyTheyreproducereproducebybybinarybinaryfissionfission..

��MostMost bacteriabacteria lacklack oror havehave veryvery fewfew internalinternal membranes,membranes, whichwhichmeansmeans thatthat theythey don’tdon’t havehave somesome kindskinds ofof organellesorganelles (like(like

mitochondriamitochondria oror chloroplasts)chloroplasts)..

��MostMost bacteriabacteria arearebenignbenign ((benignbenign == good,good, friendly,friendly, kind)kind) oror

beneficial,beneficial, andand onlyonly aa fewfew areare “bad“bad guys”guys” ororpathogenspathogens..

Difference between procaryotes and eucaryotesDifference between procaryotes and eucaryotes

PropertyProperty ProcaryotesProcaryotes EucaryotesEucaryotes

SizeSize Small cells 1Small cells 1--10mm10mm Large cells 10Large cells 10--100mm100mm

OrganismsOrganisms BacteriaBacteria Fungi, protozoa, algae, Fungi, protozoa, algae, virusvirusvirusvirus

Oxygen tolearationOxygen tolearation Anaerobic, aerobicAnaerobic, aerobic aerobicaerobic

Cell divisionCell division No mitosis, by No mitosis, by binary fissionbinary fission

Variuos forms of Variuos forms of mitosis, mitosis,

BACTERIA…BACTERIA…��There are two different ways of grouping bacteria. They can be There are two different ways of grouping bacteria. They can be

divided into three types based on their response to gaseous divided into three types based on their response to gaseous oxygen. oxygen. Aerobic bacteriaAerobic bacteriarequire oxygen for their health and require oxygen for their health and existence and will die without it. existence and will die without it. Anerobic bacteriaAnerobic bacteriacan't tolerate can't tolerate gaseous oxygen at all and die when exposed to it. gaseous oxygen at all and die when exposed to it. Facultative Facultative aneraobesaneraobesprefer oxygen, but can live without it.prefer oxygen, but can live without it.

��The second way of grouping them is by how they obtain their The second way of grouping them is by how they obtain their ��The second way of grouping them is by how they obtain their The second way of grouping them is by how they obtain their energy. Bacteria that have to consume and break down complex energy. Bacteria that have to consume and break down complex organic compounds are organic compounds are heterotrophsheterotrophs. This includes species that . This includes species that are found in decaying material as well as those that utilize are found in decaying material as well as those that utilize fermentation or respiration. Bacteria that create their own fermentation or respiration. Bacteria that create their own energy, fueled by light or through chemical reactions, are energy, fueled by light or through chemical reactions, are autotrophs.autotrophs.

BACTERIA…BACTERIA…

BACTERIA…BACTERIA…Bacteria Cell structureBacteria Cell structure: : Surface StructureSurface Structure: Beginning from the outermost structure and : Beginning from the outermost structure and moving inward, bacteria have some or all of the following moving inward, bacteria have some or all of the following structures:structures:

1) Capsule: Protective covering, made up of polysaccharides,1) Capsule: Protective covering, made up of polysaccharides,-- Important role to keep the bacterium from drying out and to protect Important role to keep the bacterium from drying out and to protect it from phagocytosis (engulfing) by larger microorganisms.it from phagocytosis (engulfing) by larger microorganisms.

--The capsule is a major virulence factor in the major diseaseThe capsule is a major virulence factor in the major disease--causing causing bacteria, such as bacteria, such as Escherichia coliEscherichia coli and and Streptococcus pneumoniae.Streptococcus pneumoniae.bacteria, such as bacteria, such as Escherichia coliEscherichia coli and and Streptococcus pneumoniae.Streptococcus pneumoniae.

22)) CellCell WallWall:: ComposedComposed ofof peptidoglycanpeptidoglycan (polysaccharides(polysaccharides ++protein),protein), thethe cellcell wallwall maintainsmaintains thethe overalloverall shapeshape ofof aa bacterialbacterial cellcell..TheThe threethree primaryprimary shapesshapes inin bacteriabacteria areare coccuscoccus (spherical),(spherical), bacillusbacillus(rod(rod--shaped)shaped) andand spirillumspirillum (spiral)(spiral).. MycoplasmaMycoplasma areare bacteriabacteria thatthathavehave nono cellcell wallwall andand thereforetherefore havehave nono definitedefinite shapeshape..

--ProtectProtect cyctoplasmiccyctoplasmic membranemembrane fromfrom thethe environmentenvironment..--alsoalso helpshelps toto anchoranchor appendagesappendages likelike thethe pilipili andand flagellaflagella..

BACTERIA…BACTERIA…33)) CytoplasmicCytoplasmic membranemembrane:: AA layerlayer ofof PhospholipidsPhospholipids && proteinsproteins

--EnclosesEncloses interiorinterior ofof bacterium,bacterium, RegulatingRegulating flowflow ofof materialsmaterials inin && outout ofofcellcell..

InternalInternal structurestructure::BacteriaBacteria havehave aa veryvery simplesimple internalinternal structure,structure, andand nonomembranemembrane--boundbound organellesorganelles..

11)) NucleoidNucleoid:: TheThe nucleoidnucleoid isis aa regionregion ofof cytoplasmcytoplasm wherewhere thethechromosomalchromosomalDNADNA isis locatedlocated.. ItIt isis notnot aamembranemembraneboundboundnucleus,nucleus,butbutchromosomalchromosomalDNADNA isis locatedlocated.. ItIt isis notnot aamembranemembraneboundboundnucleus,nucleus,butbutsimplysimply anan areaarea ofof thethe cytoplasmcytoplasm wherewhere thethe strandsstrands ofof DNADNA areare foundfound..MostMost bacteriabacteria havehave aa single,single, circularcircular chromosomechromosome thatthat isis responsibleresponsible forforreplication,replication, althoughalthough aa fewfew speciesspecies dodo havehave twotwo oror moremore.. SmallerSmaller circularcircularauxiliaryauxiliary DNADNA strands,strands, calledcalled plasmids,plasmids, areare alsoalso foundfound inin thethe cytoplasmcytoplasm..

BACTERIA…BACTERIA…2) 2) RibosomesRibosomes: Ribosomes give the cytoplasm of bacteria a granular : Ribosomes give the cytoplasm of bacteria a granular

appearance in electron micrographs. Though smaller than the appearance in electron micrographs. Though smaller than the ribosomes in eukaryotic cells, these inclusions have a similar ribosomes in eukaryotic cells, these inclusions have a similar function in translating the genetic message in messenger RNA into function in translating the genetic message in messenger RNA into the production of peptide sequences (proteins).the production of peptide sequences (proteins).

33)) StorageStorage granulesgranules:: (not(not shown)shown) NutrientsNutrients andand reservesreserves maymay bebestoredstored inin thethe cytoplasmcytoplasm inin thethe formform ofof glycogen,glycogen, lipids,lipids,storedstored inin thethe cytoplasmcytoplasm inin thethe formform ofof glycogen,glycogen, lipids,lipids,polyphosphate,polyphosphate, oror inin somesome cases,cases, sulfursulfur oror nitrogennitrogen..

44)) EndosporeEndospore:: (not(not shown)shown) SomeSome bacteria,bacteria, likelike ClostridiumClostridiumbotulinum,botulinum, formform sporesspores thatthat areare highlyhighly resistantresistant toto drought,drought, highhightemperaturetemperature andand otherother environmentalenvironmental hazardshazards.. OnceOnce thethe hazardhazard isis

removed,removed, thethe sporespore germinatesgerminates toto createcreate aa newnew populationpopulation..

BACTERIA…BACTERIA…

AppendagesAppendages: Bacteria may have the following appendages:: Bacteria may have the following appendages:

11)) PiliPili:: ManyMany speciesspecies ofof bacteriabacteria havehave pilipili (sing(sing.. pilus),pilus), smallsmall hairlikehairlikeprojectionsprojections emergingemerging fromfrom thethe outsideoutside cellcell surfacesurface.. AssistAssist thethe bacteriabacteriainin attachingattaching toto otherother cellscells andand surfaces,surfaces, suchsuch asas teeth,teeth, intestines,intestines, andandrocksrocks.. WithoutWithout pili,pili, manymany diseasedisease--causingcausing bacteriabacteria loselose theirtheir abilityability totoinfectinfect becausebecause they'rethey're unableunable toto attachattach toto hosthost tissuetissue.. SpecializedSpecialized pilipiliareare usedused forfor conjugation,conjugation, duringduring whichwhich twotwo bacteriabacteria exchangeexchangefragmentsfragmentsofof plasmidplasmidDNADNA..fragmentsfragmentsofof plasmidplasmidDNADNA..

22)) FlagellaFlagella:: FlagellaFlagella (singular,(singular, flagellum)flagellum) areare hairlikehairlike structuresstructures thatthatprovideprovide aa meansmeans ofof locomotionlocomotion forfor thosethose bacteriabacteria thatthat havehave themthem..TheyThey cancan bebe foundfound atat eithereither oror bothboth endsends ofof aa bacteriumbacterium oror allall overover itsitssurfacesurface.. TheThe flagellaflagella beatbeat inin aa propellerpropeller--likelike motionmotion toto helphelp thethebacteriumbacterium movemove towardtoward nutrientsnutrients;; awayaway fromfrom toxictoxic chemicalschemicals;; or,or, ininthethe casecase ofof thethe photosyntheticphotosynthetic cyanobacteriacyanobacteria;; towardtoward thethe lightlight..

BACTERIAL CLASSIFICATIONBACTERIAL CLASSIFICATION

��Classification means the ordering of groups into higher units.Classification means the ordering of groups into higher units.

��TheThe basicbasic unit,unit, ii..ee.. thethe purepure cultureculture ofof thethe isolatedisolated bacterium,bacterium, isis thetheSTRAINSTRAIN.. StrainsStrains areare collectedcollected intointo SPECIES,SPECIES, andand speciesspecies arearecollectedcollected intointo GENERA,GENERA, thesethese areare collectedcollected inin toto FAMILIES,FAMILIES, familiesfamiliescollectedcollected intointo ORDER,ORDER, orderorder collectedcollected intointo CLASS,CLASS, classclass collectedcollectedintointo PHYLUM,PHYLUM, phylumphylum collectedcollected intointo KINGDOMKINGDOM..

��Such classification required adequate description of strains and Such classification required adequate description of strains and proceeds by comparing the properties of various groups.proceeds by comparing the properties of various groups.

��Phyletic or Phylogenetic classification is based on evolutionary Phyletic or Phylogenetic classification is based on evolutionary relationships. Because of lack of a good fossil record, this relationships. Because of lack of a good fossil record, this classification has proven difficult for bacteria.classification has proven difficult for bacteria.

BACTERIAL CLASSIFICATION…BACTERIAL CLASSIFICATION…

��So to classify bacteria satisfactory, phenetic classification system was So to classify bacteria satisfactory, phenetic classification system was accepted, available in Bergey’s Manual of Systematic Bacteriology.accepted, available in Bergey’s Manual of Systematic Bacteriology.

��In this classification system, characteristics used to define sections are In this classification system, characteristics used to define sections are normally features such as normally features such as –– general shape and morphology,general shape and morphology,

-- GramGram--staining properties, staining properties, -- oxygen relationship, oxygen relationship, -- motility, motility,

-- presence of endospores, presence of endospores, -- the mode of energy production,etc.the mode of energy production,etc.-- presence of endospores, presence of endospores, -- the mode of energy production,etc.the mode of energy production,etc.

�� The Bergey’s Manual of Systematic Bacteriology places all bacteria in The Bergey’s Manual of Systematic Bacteriology places all bacteria in the kingdom procaryotae which in turn is divided into 4 divisions as the kingdom procaryotae which in turn is divided into 4 divisions as follows:follows:

ProcaryotaeProcaryotae

Gracilicutes(thin skin)-Gram-negativeClass

Firmicutes(strong skin)-Gram-positiveClass

Tenericutes(Soft or tender skin)

-Lacking of

Mendosicutes(skin with faults)-Unusual cell wallsClass

I.ScotobacteriaNonphotosyn II.AnoxyphotobacteriaPhotosyn, no O2III.OxyphotobacteriaPhotosyn, evolve O2

ClassI.FirmibacteriaRods or cocciII. ThallobacteriaBranching cells(Actinomycetes)

-Lacking of cell wallClassI.Mollicutes(mycoplasmas)

ClassI Archaeobacteria

Morphological ClassificationMorphological Classification��Filamentous Bacteria:Filamentous Bacteria:

1) Actinomyces: Gram positive, non1) Actinomyces: Gram positive, non--acidacid--fast,fast,

-- Tend to fragment into short coccal and bacillary forms, anaerobic, e.g. Tend to fragment into short coccal and bacillary forms, anaerobic, e.g. A. israeliA. israeli

2) Nocardia: similar to actinomyces, but aerobic, acid2) Nocardia: similar to actinomyces, but aerobic, acid--fastfast

e.g. N. farcinicae.g. N. farcinica

3) streptomyces: Vegetative mycelium, not fragmenting into short forms, 3) streptomyces: Vegetative mycelium, not fragmenting into short forms, 3) streptomyces: Vegetative mycelium, not fragmenting into short forms, 3) streptomyces: Vegetative mycelium, not fragmenting into short forms, e.g. S. griseuse.g. S. griseus

��True Bacteria:True Bacteria:

(A) Cocci: (A) Cocci:

1) Staphylococcus & Micrococcus: 1) Staphylococcus & Micrococcus:

-- Arranged in irregular clusters, due to successive division occurring Arranged in irregular clusters, due to successive division occurring irregularly in different planes, gram positive, e.g. S. aureusirregularly in different planes, gram positive, e.g. S. aureus

2) Streptococcus: 2) Streptococcus:

-- Arranged in chains, due to successive cell divisions ocurring in same Arranged in chains, due to successive cell divisions ocurring in same axis, Gram positive, e.g., S. pyogenesaxis, Gram positive, e.g., S. pyogenes

3) sarcina:3) sarcina:

-- Arranged in cubical packets of eight, or multiple of 8, due to division Arranged in cubical packets of eight, or multiple of 8, due to division occurring in 3 planes at right angles, Gram positive, e.g. S. luteaoccurring in 3 planes at right angles, Gram positive, e.g. S. lutea

4) Neisseria:4) Neisseria:

-- Arranged in pairs and slightly elongated at right angles to axis of pair, Arranged in pairs and slightly elongated at right angles to axis of pair, Gram negative, e.g. N. meningiditis.Gram negative, e.g. N. meningiditis.Gram negative, e.g. N. meningiditis.Gram negative, e.g. N. meningiditis.

5) Veillonella:5) Veillonella:

-- Very small cocci arranged in clusters and pairs, Gram negative, e.g. Very small cocci arranged in clusters and pairs, Gram negative, e.g. V. parvula.V. parvula.

(B) Bacilli:(B) Bacilli:

1. Acid1. Acid--fast bacilli: Z.N. positive, e.g. M.tuberculosisfast bacilli: Z.N. positive, e.g. M.tuberculosis

2. Gram positive 2. Gram positive –– spore forming bacilli:spore forming bacilli:

-- Either aerobic (Bacillus) or anaerobic (clostridia)Either aerobic (Bacillus) or anaerobic (clostridia)

3. Gram positive non sporing bacilli:3. Gram positive non sporing bacilli:

--Corynebacteria Corynebacteria –– club shaped, slightly curvedclub shaped, slightly curved

-- Erysipelothrix Erysipelothrix –– grow in chains or filamentsgrow in chains or filaments

-- Lectobacilli Lectobacilli –– grow in filaments but anaerobicgrow in filaments but anaerobic

-- Listeria Listeria –– flagella, motileflagella, motile

4. Gram negative bacilli: e.g. pseudomonadaceae, achromobacteriacae, 4. Gram negative bacilli: e.g. pseudomonadaceae, achromobacteriacae, 4. Gram negative bacilli: e.g. pseudomonadaceae, achromobacteriacae, 4. Gram negative bacilli: e.g. pseudomonadaceae, achromobacteriacae, enterobactericeae, Brucellaceae and bacteridaceae.enterobactericeae, Brucellaceae and bacteridaceae.

(C) Vibrios: Curved(C) Vibrios: Curved--rodrod--shaped cells, short, gram negative, motile, polar shaped cells, short, gram negative, motile, polar flagellum, e.g. V. Choleraeflagellum, e.g. V. Cholerae

(D) Spirilla : spirally twisted, gram negative, e.g. S. minus(D) Spirilla : spirally twisted, gram negative, e.g. S. minus

(E) Spirochaetes: Slender, spiral filaments, Gram negative, motile (E) Spirochaetes: Slender, spiral filaments, Gram negative, motile without flagellawithout flagella

1. Borrelia: 81. Borrelia: 8--12 fibrils, e.g. B. recurrentis12 fibrils, e.g. B. recurrentis

2. Treponema: Seen by dark2. Treponema: Seen by dark--ground microscopy, 4 fibrils, e.g. T. ground microscopy, 4 fibrils, e.g. T. pallidumpallidum

3. Leptospira: too many fibrils, e.g. L.interrogans3. Leptospira: too many fibrils, e.g. L.interrogans

Morphology of Bacteria:Morphology of Bacteria:

Size:Size: BacteriumBacterium LengthLength DiseaseDisease

StaphylococcusStaphylococcus 0.80.8µµ CarbunclesCarbunclesStaphylococcusStaphylococcus 0.80.8µµ CarbunclesCarbuncles

M. TuberculosisM. Tuberculosis 0.50.5--44µµ TuberculosisTuberculosis

S. typhiiS. typhii 0.50.5--44µµ TyphoidTyphoid

Vibrio commaVibrio comma 11--5.05.0µµ CholeraCholera

N.MeningitidisN.Meningitidis 1.01.0µµ MeningitisMeningitis

C.TetaniC.Tetani 2.02.0--5.05.0µµ TetanusTetanus

P. PestisP. Pestis 11--22µµ PlaguePlague

Shapes and arrangements of bacterial cellShapes and arrangements of bacterial cell•• 3 conventional shapes of the cells3 conventional shapes of the cells1) Ellipsoidal or Cocci: appears like a minute sphere. Classify1) Ellipsoidal or Cocci: appears like a minute sphere. Classifya)Micrococci a)Micrococci –– appears singlyappears singlyb)Diplococci b)Diplococci –– appear in pairsappear in pairsc)Streptococcic)Streptococci-- appear in rows of cells or in chainsappear in rows of cells or in chainsd)Tetrads d)Tetrads –– arrange in square of fourarrange in square of foure)Staphylococci e)Staphylococci –– arrange in bunches of grapesarrange in bunches of grapesf)Sarcinae f)Sarcinae ––arrange in cuboidal or packet arrangementarrange in cuboidal or packet arrangementf)Sarcinae f)Sarcinae ––arrange in cuboidal or packet arrangementarrange in cuboidal or packet arrangement

2) Cyllindrical or Rod 2) Cyllindrical or Rod ––Shaped: BacilliShaped: Bacilli-- Appear like stick or rod, some times curvedAppear like stick or rod, some times curveda) Diplobacilli: appear in pairsa) Diplobacilli: appear in pairsb) Streptobacilli: appear in chainsb) Streptobacilli: appear in chains

3) Spiral or helicoidal shaped: helical forms known as vibrio or spirilla. 3) Spiral or helicoidal shaped: helical forms known as vibrio or spirilla. Appear like corkAppear like cork--screw.screw.

Different shapes of bacteria and positions of flagella.