This is a series of lectures on microbiology useful for undergraduate medical and paramedical students

1. (How Much)
Do We Know
?

2. Q-1
• Who had a flair for working with
lenses and discovered the basic
instrument of microbiology
• A. Robert Koch
• B. Joseph Lister
• C. Antony Van Leuuewenhoek
• D. Christian Gram

3. Microscope
• Antony van leeuwenhoek –
father of microbiology
• Draper
• Developed interest in lens
making from glass and
observing things through them
• Little animalcules

7. Q-2
• Identify the gentleman

9. Vaccination
• Milkmaids who had
occupational exposure to cow
pox did not get small pox
• Edward Jenner
• observed that when extract
from cowpox lesion was
injected into a person
unaffected by small pox, it gave
immunity

10. Q-3
• Which branch of microbiology
deals with blood grouping?
• A. immunology
• B. serology
• C. Virulogy
• D. Antigen-antibody reactions

11. Serology
• Study of these antibodies and
antigens in body fluids
• Blood grouping

13. Q-4
• Which among the following
statements is true?
• A. Fungi are eukaryotes
• B. viruses have cell wall
• C. Bacteria have nucleus
• D. Parasites are prokaryotes

14. Classification of
Microorganisms
• Classification by structure
• Subcellular – DNA or RNA surrounded by
a protein coat – viruses
• Prokaryotic – simple cell structure with
no nucleus or organelles – bacteria
• Eukaryotic – complex cell structure with
nucleus and specialized organelles –
protozoans, fungi, parasites

15. • Protozoans – single celled
eukaryotes
• Fungi – multicelled eukaryotes
with cell wall
• Parasites – multicelled
eukaryotes without cell wall

16. Classification of
Microorganisms
• Structure

17. Q-5
• Which class of organism causes
the following illness

19. •
•
•
•
A.
B.
C.
D.
Virus
Bacteria
fungi
Protozoa

20. Protozoans
• Single-celled eukaryotic organisms,
larger than bacteria
• Found in soil and water
• Illnesses
• Malaria
• Amebic dysentery
• Trichomoniasis vaginitis
• Leading cause of death in developing
countries

21. Q-6
• What is the type of culture seen
in next picture used for?

23. •
•
•
•
A.
B.
C.
D.
Antibiotic Specificity Testing
Antibody Sensitivity testing
Growing in pure culture
Antibiotic sensitivity testing

24. Determining
Antimicrobial Sensitivity

25. Q-7
• What is the unit of
measurement of a bacterium
cell wall?
• A. meter
• B. Nanometer
• C. Micrometer
• D. centimeter

27. Size of Bacteria
• Unit of measurement in bacteriology
is the micron (micrometre, µm)
• 1 micrometre (10-6)= 1/1000 mm =
1/10000 cm = 1/100000 metre
• 1 nanometer (10-9)= 1/1000
micrometer = 1/100000000 meter
• Bacteria of medical importance
• 0.2 – 1.5 µm in diameter
• 3 – 5 µm in length

28. Anatomy of a
Bacterial Cell

29. CELL WALL
•
Outermost layer, encloses cytoplasm
1.Confers shape and rigidity
2.10 - 25 nm thick
3.Composed of peptidoglycan

30. Q-8
• What is the process of
reproduction of bacteria known
as?
• A. replication
• B. regeneration
• C. duplication
• D. Binary fission

31. Binary Fission
• DNA replication
• Plasma membrane invaginate
• Cell wall deposited in
invaginated space
• Cross wall completed
• Cells separate

32. Binary Fission
• Light micrograph

33. Binary Fission

34. Consequences of Binary
Fission
• Very large number of cells very
fast
• Mathematical progressions
• arithmetic
(1>2>4>6>8>10>12>14>16)
• geometric(1>2>4>8>16)
• exponential expression (20 > 21 > 22
>23>24)
• logarithmic expression(0
>log21>log22>log23>log24)

35. Q-9
• During which phase of bacterial
growth curve, is the growth
fastest?
• A. Lag phase
• B. Log phase
• C. Death phase
• D. Stationary phase

36. Bacterial Growth Curve
Stationary phase
Death
phase
Log phase
Lag phase
1
5
Time (hours)
10

37. Final question…Thank
God!
• Which type of liquid culture
medium contains an inhibitory
substance added to it?
• A. Enriched Media
• B. Enrichment Media
• C. Selective Media
• D. Indicator Media

38. Enriched media
• Substances like blood, serum, egg
are added to the basal medium.
• Used to grow bacteria that are
exacting in their nutritional
needs.
• Eg: Blood agar, Chocolate agar

39. Blood agar
Chocolate agar

40. Enrichment media
• Liquid media used to
isolate pathogens from a
mixed culture.
• Media is incorporated
with inhibitory
substances to suppress
the unwanted organism.
• Eg:
• Selenite F Broth – for the
isolation of Salmonella,
Shigella
• Alkaline Peptone Water –

41. Selective media
• The inhibitory substance is added
to a solid media.
Eg:
• Mac Conkey’s medium for gram
negative bacteria
• TCBS – for V.cholerae
• LJ medium – M.tuberculosis
• Wilson and Blair medium – S.typhi
• Potassium tellurite medium –
Diphtheria bacilli

42. Mac Conkey’s medium
TCBS

43. Potassium Tellurite media
LJ media

44. Indicator media
• These media contain an indicator
which changes its colour when a
bacterium grows in them.
• Eg:
• Blood agar
• Mac Conkey’s medium
• Christensen’s urease medium

46. Urease medium

47. Hope u enjoyed