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1、LaboratoryMethodsForIdentificationOfBacteria Bacteriaareeitheridentifiedin Apathologicalspecimenobtainedfromthepatient e g pus sputum urine blood stools etc dependingonthesiteofinfection Afterbeengrownonartificialnutrientmedia Bacteriaarethenidentifiedby MicroscopicExamination Examinationoffreshsamp
2、lesusedfordemonstrationofbacterialmotility usinghangingdropmethod Morphologyandstainingreactionsofbacteria Commonlyusedstainsare Simplestains e g methylenebluestain Differentialstains e g Gramstain Primarystain Methylviolet Iodinemixture DecolourizationwithAlcohol Counterstain Dilutedcarbolfuchin Re
3、sults Gram PurpleGram RedDifference duetostructureofcellwallGram ThickcellwallGram Thincellwall a Acidfaststain Ziehl Neelsenstain DifferentialStain dividesbacteriainto2groupsAcid FastNonAcid FastUsedtoidentifyorganismsintheGeneraMycobacterium highlipidandwaxcontentincellwall 1 Carbolfuchsin Red 2 D
4、ecolourizationbysulphuricacid20 3 CounterstainwithMethyleneblue Acid Fastorganism RedasMycobacteriumtuberculosisNonAcid Fastorganism BlueSpecialstains e g Capsulestain flagellastain II CulturalCharacters Bacterianeednutritiveculturemediatomultiplyinvitro Anundefinedmedium alsoknownasabasalorcomplexm
5、edium Itisamediumthatcontains 1 Acarbonsourcesuchasglucoseforbacterialgrowth2 Water3 Varioussaltsneededforbacterialgrowth Definedmedia alsoknownaschemicallydefinedmediaorsyntheticmedia ClassificationofMedia Mediacanbeclassifiedinto 1 Minimalmedia simplemedium Itcontainsthebasicnutritiverequirements
6、e g nutrientbrothsandagarmedia 2 Selectivemedia Selectivemediaareusedforthegrowthofonlyselectivemicrobes Itcontainsantibiotics dye orspecificchemicalsthatinhibitsthegrowthofmosttypesofmicrobeandstimulatetheisolationofonetype Mannitolsaltagar MSA whichisselectiveforGram vebacteria Blood free charcoal
7、 basedselectivemediumagar CSM forisolationofCampylobacter Lowenstein Jensenmedium enrichedselectivemediaforT B T C B S Thiosulphate Citrate Bile Sucroseagar selctiveforVibriocholeraduetoalk pH 3 Differentialmedia Differentialmediaorindicatormediadistinguishonemicroorganismtypefromanothergrowingonthe
8、samemedia Indicators suchasneutralred phenolred eosiny ormethyleneblue Examplesofdifferentialmediainclude Eosinmethyleneblue EMB whichisdifferentialforlactoseandsucrosefermentation MacConkey MCK whichisdifferentialforlactosefermentation 4 Enrichedmedia Enrichedmediacontainthenutrientsrequiredtosuppo
9、rtthegrowthofawidevarietyoforganisms includingsomeofthemorefastidiousones Bloodagar Isanenrichedmediuminwhichnutritionallyrichwholebloodsupplementsthebasicnutrients Itcontains5 10 humanoranimalblood Itshowsthetypeofhaemolyticactivityofbacteria complete partialornon haemolytic CompletePartialHaemolys
10、isofHaemolysisRBCsofRBCs Beta AlphaHaemolyticHaemolyticStreptococci Streptococci Chocolateagar heatedbloodagar isenrichedwithheat treatedblood 40 45 C Lofflersserummedia Horseserum glucoseinaratio3 1ItisusedforcultivationofCorynbacteriumdiphtheria 5 Transportmedia Transportmediumisasimpleorganicmedi
11、umthatMaintaintheviabilityofallorganismsinthespecimenwithoutalteringtheirconcentration ThistypeofmediummainlyusedforTemporarystorageofspecimensbeingtransportedtothelaboratoryforcultivation Examplesoftransportmediainclude Thioglycolatebrothforstrictanaerobes Thecolonialappearanceonculturemedia Shape
12、Thecoloniesmaybesmall pin point fimbriate flatorconvex Colour Thecoloniesmaybecolourlessorbacteriaproduceendopigmentswhichgivethecoloniesacharacteresticcolour e g Staph aureusproducegoldenyellowcolonies Staph albusproducewhiteendopigment Staph Citreusproducealemonyellowendopigment Thebacteriamayprod
13、uceexopigments e g Pseudomonasaeruginosaproduceagreenexopigmentinthesurroundingmedia AntimicrobialChemotherapy Anantibacterialagentisacompoundorsubstancethatkillsorslowsdownthegrowthofbacteria Antibiotic s hascometoincludeabroaderrangeofantimicrobialcompounds includinganti fungalandothercompounds It
14、isproducedbymicrobesandisharmfultoothermicrobes exceptviruses Theseinclude forexample thebeta lactamantibacterials whichincludethepenicillins producedbyfungiinthegenusPenicilliumnotatum andthecephalosporins Compoundsthatarestillisolatedfromlivingorganismsaretheaminoglycosides whereasotherchemotherap
15、euticagents forexample thesulfonamides andthequinolones areproducedbychemicalsynthesis ClassificationofAntibiotics Accordingtoagentaction Inthisclassificationantibacterialagentsaredividedintotwobroadgroupsaccordingtotheirbiologicaleffectonmicroorganisms bactericidalagentskillbacteria andbacteriostat
16、icagentsslowdownorstallbacterialgrowth Bactericidalantibiotics Antibioticsthatinhibitcellwallsynthesis theBeta lactamantibiotics penicillinderivatives andcephalosporins Aminoglycosidicantibioticsareusuallyconsideredbactericidal althoughtheymaybebacteriostaticwithsomeorganisms Bacteriostaticantibioticslimitthegrowthofbacteriabyinterferingwithbacterialproteinproduction DNAreplication orotheraspectsofbacterialcellularmetabolism Thisgroupincludes Tetracyclines sulphonamides trimethoprim chlorampheni
