this lecture describes the conventional procedures for identification of bacterial colonies using different tests. the lecture is suitable for the medical students, technicians and medical staff.

1. CONVENTIONAL METHODSCONVENTIONAL METHODS
FORFOR
BACTERIAL IDENTIFICATIONBACTERIAL IDENTIFICATION
Dr Mostafa Mahmoud Ahmed, Ph DDr Mostafa Mahmoud Ahmed, Ph D
Consultant 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

3. Methods for IdentificationMethods for Identification
A- Phenotypic Characteristics:
1- Appearance
Colonial morphology
Microscopic appearance
2- Biological activity
Enzyme production,
Sugar fermentation
3- Immunophenotyping (serotyping): presence
of specific antigens (O, H, K,….)
B- Genotyping and Molecular identification

4. Macroscopic AppearanceMacroscopic Appearance
Growth onGrowth on
Culture MediaCulture Media

5. Growth in Fluid MediaGrowth in Fluid Media
Uniform

6. FlocculentSediment

8. Colonial MorphologyColonial Morphology

9. 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

10. SIZESIZE
• Pinpoint
• Small
• Medium
• Large

11. 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

12. Edge (MarginEdge (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.

13. 2- Serrate
This means a saw-toothed
edge to a colony.
3- Undulate
Undulate margins are
a regular pattern of
waviness around
the colony.

14. 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.

15. 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.

16. Swarming GrowthSwarming Growth
• Usually denotes highly motile organism
(e.g. proteus)

19. 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.

20. 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.

21. ELEVATIONELEVATION
ConsistencyConsistency
Flat Raised Convex Umbonate
Soft, Mucoid, Sticky
Tough, Hard

22. SURFACESURFACE
Smooth, Shiny
Rough, Dull

23. Pigment ProductionPigment Production
1- Non-pigmented (nonchromogenic)
2- Pigmented (Chromogenic)
Endopigment Exopigment

24. Endopigment

25. Different Endopigments

26. Effect on Blood agarEffect on Blood agar
(Hemolysis Types(Hemolysis Types((

27. No hemolysis (No hemolysis (γγ((

28. Complete Hemolysis (Complete Hemolysis (ββ((

29. Partial Hemolysis (Partial Hemolysis (αα((

30. Identify??

31. Identify??

32. Growth on MacConkey’s mediaGrowth on MacConkey’s media
LFC
NLFC

33. Identify??

34. Identify??

35. Identify??

39. Microscopic ExaminationMicroscopic Examination
• Cocci, Bacilli, comma-shape - Arrangement
• Reaction to Gram stain (+ve, -ve, Variable)
• Capsule, spore formation
• Motility (motile, non-motile).

40. Motility testMotility test

41. Special tests for enzymaticSpecial tests for enzymatic
productionproduction
1. Catalase test
2. Oxidase test
3. Gelatinase test
4. Urease test
5. Tryptophanase (Indole test)
6. Cysteinase (H2S production)

42. CatalaseCatalase

44. Oxidase testOxidase test

45. Gelatinase (ProteinasesGelatinase (Proteinases((
Positive
Negative

46. Urease ProductionUrease Production
Positive Negative

47. Indole testIndole test
PositiveNegative

48. H2S ProductionH2S Production
PositiveNegative

49. Citrate Utilization testCitrate Utilization test

50. Test for End product ofTest for End product of
fermentationfermentation

51. Litmus MilkLitmus Milk

52. Triple Sugar Iron MediaTriple Sugar Iron Media
(TSI(TSI((
Slant
Butt

53. Triple Sugar Iron MediaTriple Sugar Iron Media
(TSI(TSI((

55. Analytical Profile Index (API)Analytical Profile Index (API)
SystemSystem

57. E.coliE.coli

58. KlebseillaKlebseilla

59. Salmonella typhiSalmonella typhi

61. Broad Spectrum antibioticBroad Spectrum antibiotic

62. Emergence of ResistanceEmergence of Resistance

63. Targeted therapyTargeted therapy

64. To the
target

65. DISC Diffusion MethodDISC Diffusion Method

68. Highly Resistant BacteriaHighly Resistant Bacteria

69. Broth Dilution MethodBroth Dilution Method
Determining MICDetermining MIC

70. MIC

71. Microdilution traysMicrodilution trays

72. Reading of OD for microdilution

73. E-testE-test

74. E-test

75. E-Test for exopigment producing
organism

76. E-Test for fastidious
microorganism

77. Identification of some microorganism

78. Identification of some microorganism

79. Identification of some microorganism

80. Identification of some microorganism

81. Identification of some microorganism

82. Identification of some microorganism

83. Thank You