Fundamentals of Medicine (Pathology) Introduction to Microbiology

1. Fundamentals of Medicine (Pathology)Introduction to Microbiology Peter Gayo Munthali Consultant Microbiologist UHCW

2. Aim To introduce to you general principles in microbiology with an emphasis on bacteria and viruses

3. Objectives • By the end of the session you should be able to; • Describe the role of a clinical microbiologist/virologist in patient care • Describe the difference between bacteria and viruses. • Distinguish between gram-positive and gram-negative bacteria • Describe bacteria by their shape as either cocci or rods • Describe the relationship between viruses and cells in viral multiplication • Name some common bacterial and viral diseases linked to their causative organisms • Describe in broad terms, how antibiotics work on bacteria • Describe the importance of infection control in health care

4. What is Microbiology • The study of micro-organisms that cause disease • Bacteria (Bacteriology) • Viruses (Virology) • Parasites (Parasitology) • Fungi (Mycology)

5. Size Matters 1nm 10nm 100nm 1 µm 10 µm 100µm 1mm Light microscope Electron Microscope Proteins Viruses Plant and animal cells Bacteria Small molecules

6. 1. Bacteria

7. Description • Unicellular • Prokaryotic • Primitive nucleus • No nucleus membrane • Genome • Single circular molecule double stranded DNA • Can harbour independent small circular DNA molecules called plasmids • Structure • Rigid wall which determines their shape

8. Bacteria and Human body • Bacteria >10x than human cells in the body (10¹ versus 10¹³) • Skin surface and in deep layers • Saliva and oral mucosa • Gastrointestinal tracts • Normal microbiota or microflora • Beneficial to human health • Opportunistic infections • < 10% culturable • Others not part of normal microbiota • Pathogenic • Opportunistic pathogens

9. Bacteria Classification • Cell wall classification by gram-stain • Gram positive-thicker cell wall • Gram negative-thinner cell wall • Classification by shape • Spherical-Cocci • Cylindrical-Rods/bacilli

10. Bacteria Classification

11. Gram Stain Gram-negatives Gram-Positives Gram-negative rods Gram-positive cocci in clusters (Staphylococci) Gram-positive rods Gram-positive Cocci in chains (Streptococci) Gram-negative cocci

12. Sub classification-Streptococcus Short Chain Diplococci Beta (β) haemolysis Long Chain Gamma (γ) No Haemolysis Alpha (α) haemolysis

13. Cell Division (binary fission )

14. Bacterial Cell Division Super coiled DNA DNA relaxation and duplication Duplication of the DNA bacterial chromosome replicates leading to two identical chromosomes Enzymatic Cleavage Division Identical Daughter cells

15. Bacterial Diseases

16. Impetigo Staphylococcus aureus β haemolytic Streptococci

17. Rash due to Septicaemia Meningitis, Post-mortem Neisseria meningitidis Streptococcus pneumoniae Gangrene Secondary to Septicaemia

18. Pneumonia Community Acquired Pneumonia Streptococci pneumoniae Consolidation “Atypical Pneumonia” Legionella E.coli Hospital Acquired Pneumonia

19. Beta Haemolytic Streptococci Group A Necrotising Fascitis

20. Antibiotics • Actions • Bactericidal • Kills bacteria, reduces bacterial load • Bacteriostatic • Inhibit growth and reproduction of bacteria

21. Antibiotics Against Bacterial Cell Wall Cell wall Osmotic Pressure Cell Membrane Antibiotic against cell wall Osmotic Pressure Cell membrane Rapture

22. Antibiotics Against Protein Synthesis • Interferes with bacterial protein synthesis • Limits bacterial growth • Limits DNA replication • Limits bacterial cellular metabolism • Bacterial growth and reproduction inhibited

23. Antibiotic Susceptibility Testing By Disc Diffusion method Antibiotic Disc Zone of Inhibition Diameter of Zone of Inhibition Sensitive/Resistant Quick Convenient

24. Viruses

25. Description • Small infectious agents that can replicate only inside the living cells of organisms • Do not possess enough of their own machinery to replicate independently • Bacteria replicate independently

26. Viral Classification • More complex than bacteria • Nucleic acid • DNA • RNA • Morphology • Enveloped • Naked

27. DNA viruses And Associated Diseases

29. Viruses by Electron Microscopy

30. Chicken Pox Shingles Varicella Zoster Virus

31. Small Pox

32. RNA Viruses And Associated Disease

34. Global status Polio 2003

35. Noro Virus

36. Human Immunodeficiency Virus (HIV) Viral Fungal Opportunistic Infections Opportunistic Infections Opportunistic Infections Parasites Bacterial Opportunistic Infections

37. Viral Replication

38. Viral Genome • DNA or RNA • Double-stranded • Single-stranded • RNA viruses • Intact or segmented

39. Viral Replication-Key Points • Need to be in a live cell to replicate • Uses cell machinery for replication • Some individual differences according to viral genome and particular virus

40. Fungi • Structure • Classification

41. Fungi Classification Yeast Moulds Unicellullar,reproduce by budding Filamentous ,produce by spores

42. Yeast-Candida Candida, Gram-stain Streptococci

43. Candidiasis

44. Moulds-Aspergillus Aspergillus flavus Top Bottom Aspergillus fumigatus

45. Aspergillus , Microscopic appearance Scanning Electron Microscopy

46. Mould sinus infection Mould Infections Aspergilloma

47. The Role of Microbiologist in healthcare • Management of diagnostic laboratories • Management of infections • Antibiotics advice, choice and duration • Choice of appropriate investigations • Infection prevention and control in hospital and the community • Investigation, management and control of outbreaks of infections • MRSA, Clostridium difficile, Noro virus • Commissioning of theatres, decontamination of facilities and wards

48. Never Forget Infection Control! Noro Virus

49. Summary • Microbiology is a very interesting discipline • Spans across all medical specialties