An overiew of medical microbiology for Clinical medicine , nursing community health , plaster technician diploma and certificate level

1. North coast mtc
INTERMEDIATE LECTURE
MARCH 2017 introductory group
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

2. BACTERIAL CELL
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

3. Cell wall
• In addition to conferring rigidity upon
bacteria, the cell wall protects against osmotic
damage
• Chemically, the rigid part of the cell wall is
peptidoglycan
• First described by Gram in 1884. It is' used to
study morphologic appearance of bacteria.
Gram's stain differentiates all bacteria into
two distinct groups:
• a. Gram-positive organisms
• b. Gram-negative organismsWALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

4. fuchsine
Gram
Staining
Technique
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

5. Introduction to Virology
• Recognizing the shape, size, and
structure of different viruses is critical to
the study of disease
• Viruses have an inner core of nucleic acid
surrounded by protein coat known as an
envelope
• Most viruses range in sizes from 20 – 250
nanometers
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

6. Viral Properties
• Viruses are inert (nucleoprotein ) filterable Agents
• Viruses are obligate intracellular parasites
• Viruses cannot make energy or proteins independent
of a host cell
• Viral genome are RNA or DNA but not both.
• Viruses have a naked capsid or envelope with
attached proteins
• Viruses do not have the genetic capability to multiply
by division.
• Viruses are non-living entities
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

7. VIRAL STRUCTURE – SOME
TERMINOLOGY
• virus particle = virion
• protein which coats the genome =
capsid
• capsid usually symmetrical
• capsid + genome = nucleocapsid
• may have an envelope
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

8. Virion Structure
Nucleic Acid
Spike
Projections
Protein
Capsid
Lipid Envelope
Virion
Associated
Polymerase
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

9. Distinguishing characteristics of
viruses
• Obligate intracellular parasites
• Extreme genetic simplicity
• Contain DNA or RNA
• Replication involves disassembly
and reassembly
• Replicate by "one-step growth”
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

10. How are viruses named?
• Based on:
- the disease they cause
poliovirus, rabies virus
- the type of disease
murine leukemia virus
- geographic locations
Sendai virus, Coxsackie virus
- their discovers
Epstein-Barr virus
- how they were originally thought to be contracted
dengue virus (“evil spirit”), influenza virus (the “influence” of bad air)
- combinations of the above
Rous Sarcoma virus
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

11. 5 BASIC TYPES OF VIRAL STRUCTURE
HELICAL ENVELOPED HELICAL
ENVELOPED ICOSAHEDRAL
COMPLEX
ICOSAHEDRAL
Adapted from Schaechter et al., Mechanisms of Microbial Disease
nucleocapsidicosahedral nucleocapsid
nucleocapsid
helical nucleocapsid
lipid bilayer
lipid bilayer
glycoprotein spikes
= peplomers
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

12. Virus classification
• More recently a precise ordering of viruses
within and between families is possible based
on DNA/RNA sequence
• By the year 2000 there were over 4000 viruses
of plants, animals and bacteria - in 71 families,
9 subfamilies and 164 genera
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

13. PROPERTIES OF NAKED VIRUSES
• Stable in hostile environment
• Not damaged by drying, acid, detergent, and heat
• Released by lysis of host cells
• Can sustain in dry environment
• Can infect the GI tract and survive the acid and bile
• Can spread easily via hands, dust, fomites, etc
• Can stay dry and still retain infectivity
• Neutralizing mucosal and systemic antibodies are
needed to control the establishment of infection
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

14. Eg.NAKED VIRUSES( NON
ENVELOPED )
• Adenovirus
• Coxsackievirus
• Hepatitis A Virus (HAV)
• Hepatitis E Virus (HEV)
• Norwalk Virus
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

15. ENVELOPE
• OBTAINED BY BUDDING THROUGH A
CELLULAR MEMBRANE (except poxviruses)
• POSSIBILITY OF EXITING CELL WITHOUT
KILLING IT
• CONTAINS AT LEAST ONE VIRALLY CODED
PROTEIN
– ATTACHMENT PROTEIN
• LOSS OF ENVELOPE RESULTS IN LOSS OF
INFECTIVITY
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

16. Viral Replication Differences
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

17. WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY
ENVELOPED AND NAKED VIRAL REPLICATION CYCLE

18. 1.ATTACHMENT
• Attachment- Receptors on the viral envelope
become connected to complementary
receptors on the cell membrane.
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

19. WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

20. Endocytosis vs. Membrane Fusion
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

21. 2.UNCOATING
• NEED TO MAKE GENOME AVAILABLE
• ONCE UNCOATING OCCURS, ENTER ECLIPSE
PHASE
• ECLIPSE PHASE LASTS UNTIL FIRST NEW
VIRUS PARTICLE FORMED
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

22. 3.SYNTHESIS OF VIRAL NUCLEIC ACID
AND PROTEIN
• MANY STRATEGIES
• NUCLEIC ACID MAY BE MADE IN
NUCLEUS OR CYTOPLASM
• PROTEIN SYNTHESIS IS ALWAYS IN
THE CYTOPLASM
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

23. DNA Virus Biosynthesis
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

24. Retroviruses
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

25. Viral Assembly
• DNA
– Nucleus
– Moves to cytoplasm
• RNA
– cytoplasm
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

26. Viral Release
• Types
– Budding
• Acquire membranes
• envelope
– Exocytosis
– Lysis
• Latency
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

27. Budding
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

28. Viral Exocytosis
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

29. Viral Lysis
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

30. PARASITOLOGY
• PROTOZOAN
• HELMINTHES
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

31. PROTOZOA
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

32. Of medical importance[PROTOZOA]
• AMOEBA
– Entamoeba
• FLAGELLATES
– Giadia lamblia
– Trichomonas vaginallis
– Trypanosoma species
– Leishmania species
• SPOROZOANS
– Plasmodium
– Toxoplasma gondii=opportunistic infections
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

33. helminthology
helminth
Platy helminthes
Cestodes and
trematodes
Flattened,leaf
liketape and
segmented
Mostly
hermophrodites
Nemathelminthes
nematodes
Elongated,cylendrical,
unsegmented
Sex separete
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

34. helminthes
cestodes
• Tapelike
• Segmented
• Monoecious
• Suckers w.hooks
• No alimentary
canal
• No body cavity
trematodes
• Leaf like
• Unsegmented
• Monoecious
except
schistosomes
• Suckers no hooks
• Present
alimentary canal
but no anus
• No body cavity
nematodes
• Elongated
• Cylendrical
• unsegmented
• Diecous
• No suckers
• No hooks
• Buccal capsule
• Alimentary canal
present
• Anus present
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

35. HELMINTHES
cestode trematode
nematodes
image
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

36. CLASSIFICATION
• Depending on cell morphology
1. Yeasts
2. Yeast like fungi
3. Molds
4. Dimorphic fungi
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

37. 1.Yeasts
• Unicellular fungi
which reproduce by
budding
• On culture -
produce smooth,
creamy colonies
e. g Cryptococcus
neoformans
(capsulated yeast)
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

38. 2.Yeast like fungi
• Grow partly as yeasts and partly as
elongated cells resembling hyphae which
are called pseudo hyphae. e.g. Candida
albicans
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

39. 3.Molds/ Filamentous fungi
• Form true mycelia &
reproduce by formation
of different types of
spores.
• Vegetative/ aerial
hyphae
e.g. Rhizopus, Mucor
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

40. 4. Dimorphic fungi
• Occur in 2 forms
Molds (Filaments) – 25C (soil)
Yeasts – 37C (in host tissue)
Most fungi causing systemic infections are
dimorphic:
– Histoplasma capsulatum
– Blastomyces dermatidis
– Paracoccidioides brasiliensis
– Coccidioides immitis
– Penicillium marneffei
– Sporothrix schenkii
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

41. Reproduction in fungi
• Sexual - formation of Zygospore, ascospores or
basidiospores
• Asexual reproduction – budding or fission
• Asexual spores are formed on or in specialized
structures.
• Vary in size, shape & colour but these
characteristics are constant for a particular
species.
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

42. conidia-asexual reproductive
structure –can be inhaled
• Micro conidia
- Small, single
celled
• Macro conidia
– Large, single or
many celled
• Seeds
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

43. Structure
• The main body of most fungi is made up of fine,
branching, usually colourless threads called
hyphae
• Several of these these hyphae, all intertwining to
make up a tangled web called the mycelium
• Most fungi are multinucleate and multicellular
organisms with cross wall called septa or aseptate
(coenocytic)
• Yeasts are unicellular
• One major difference is that most fungi have cell
walls that contain chitin, unlike the cell walls of
plants, which contain celluloseWALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

44. Single Hyphae
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY

45. Fungal Infections/ Mycoses
• superficial
• CUTANEOUS MYCOSES
• SUBCUTANEOUS MYCOSES
• SYSTEMIC
• OPPORTUNISTIC
• FUNGAL TOXINS AND ALLERGIES
WALTER WAKHUNGU WASWA
BSC.MLS, MPH/MSC MICRO
CANDIDATE PWANI

46. The end
WALTER WAKHUNGU WASWA BSC.MLS,
MPH/MSC MICRO CANDIDATE PWANI
UNIVERSITY