conventional methods for bacterial identification
TRANSCRIPT
CONVENTIONAL METHODS CONVENTIONAL METHODS FOR FOR
BACTERIAL IDENTIFICATIONBACTERIAL IDENTIFICATION
Dr Mostafa Mahmoud Ahmed, Ph DDr Mostafa Mahmoud Ahmed, Ph DConsultant Microbiologist, GDHA, Riyadh, KSA.Consultant Microbiologist, GDHA, Riyadh, KSA.Associate Prof. of Microbiology & Immunology.Associate Prof. of Microbiology & Immunology.
Faculty of Medicine – Ain Shams UniversityFaculty of Medicine – Ain Shams University
Methods for IdentificationMethods for IdentificationA- Phenotypic Characteristics:
1- AppearanceColonial morphologyMicroscopic appearance
2- Biological activityEnzyme production, Sugar fermentation
3- Immunophenotyping (serotyping): presence of specific antigens (O, H, K,….)
B- Genotyping and Molecular identification
Macroscopic AppearanceMacroscopic Appearance
Growth on Growth on Culture MediaCulture Media
Growth in Fluid MediaGrowth in Fluid Media
Uniform
FlocculentSediment
Colonial MorphologyColonial Morphology
Colonial MorphologyColonial Morphology• Size• Shape• Surface• Pigment production People• Consistency Come• Edge (margin)• Elevation• Opacity Other• Effect on Blood agar are Badly• Lactose fermentation Late
Some
Early
SIZESIZE
• Pinpoint• Small• Medium• Large
The shapes of colonies describes the entire colony, while the margin describes the edges.
Colonies may be circular or regular, irregular and punctiform.
A punctiform colony is too small to describe as either regular or irregular.
Circular
Irregular
ShapeShape
Edge (Margin)Edge (Margin)
1- Entire • This means that the edge of the colony is
distinct all of the way around the colony, and many of the colonies found on plates will be described as circular with entire margins.
2- Serrate This means a saw-toothed edge to a colony.
3- Undulate Undulate margins are a regular pattern of waviness around the colony.
4- Lobate • This means the colony forms lobes at
irregular intervals. It may be difficult to distinguish between undulate and lobate at times – they are imprecise distinctions.
5- Diffuse edge (Swarmming growth)• This means the colony fades away from
the densest part making it difficult to tell where the edge of the colony is.
Swarming GrowthSwarming Growth
• Usually denotes highly motile organism (e.g. proteus)
Rhizoid and filamentous • Both are used to describe both the shape
and the margin of a colony. 6- Rhizoid • This means root-like, and describes thick
branchlike growths originating from the center of a colony becoming thinner as a result of sequential branching.
7- Filamentous • They are the result of growth filaments of
equal width that pile on top of one another forming a thicker part in the center.
ELEVATIONELEVATION
ConsistencyConsistency
Flat Raised Convex Umbonate
Soft, Mucoid, Sticky
Tough, Hard
SURFACESURFACESmooth, Shiny
Rough, Dull
Pigment ProductionPigment Production1- Non-pigmented (nonchromogenic)2- Pigmented (Chromogenic)
Endopigment Exopigment
Endopigment
Different Endopigments
Effect on Blood agar Effect on Blood agar (Hemolysis Types)(Hemolysis Types)
No hemolysis (No hemolysis (γγ))
Complete Hemolysis (Complete Hemolysis (ββ))
Partial Hemolysis (Partial Hemolysis (αα))
Identify??
Identify??
Growth on MacConkey’s mediaGrowth on MacConkey’s media
LFC
NLFC
Identify??
Identify??
Identify??
Microscopic ExaminationMicroscopic Examination• Cocci, Bacilli, comma-shape - Arrangement• Reaction to Gram stain (+ve, -ve, Variable) • Capsule, spore formation• Motility (motile, non-motile).
Motility testMotility test
Special tests for enzymatic Special tests for enzymatic productionproduction
1. Catalase test2. Oxidase test3. Gelatinase test4. Urease test5. Tryptophanase (Indole test)6. Cysteinase (H2S production)
CatalaseCatalase
Oxidase testOxidase test
Gelatinase (Proteinases)Gelatinase (Proteinases)
Positive
Negative
Urease ProductionUrease Production
Positive Negative
Indole testIndole test
PositiveNegative
H2S ProductionH2S Production
PositiveNegative
Citrate Utilization testCitrate Utilization test
Test for End product of Test for End product of fermentationfermentation
Litmus MilkLitmus Milk
Triple Sugar Iron MediaTriple Sugar Iron Media(TSI)(TSI)
Slant
Butt
Triple Sugar Iron MediaTriple Sugar Iron Media(TSI)(TSI)
Analytical Profile Index (API)Analytical Profile Index (API)SystemSystem
E.coliE.coli
KlebseillaKlebseilla
Salmonella typhiSalmonella typhi
Broad Spectrum antibioticBroad Spectrum antibiotic
Emergence of ResistanceEmergence of Resistance
Targeted therapyTargeted therapy
To the target
DISC Diffusion MethodDISC Diffusion Method
Highly Resistant BacteriaHighly Resistant Bacteria
Broth Dilution MethodBroth Dilution MethodDetermining MICDetermining MIC
MIC
Microdilution traysMicrodilution trays
Reading of OD for microdilution
E-testE-test
E-test
E-Test for exopigment producing organism
E-Test for fastidious microorganism
Identification of some microorganism
Identification of some microorganism
Identification of some microorganism
Identification of some microorganism
Identification of some microorganism
Identification of some microorganism
Thank You