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

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

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

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

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

1. Bacteria

Description Unicellular Prokaryotic Genome Structure 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

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

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

Bacteria Classification

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

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

Cell Division (binary fission )

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

Bacterial Diseases

Impetigo Staphylococcus aureus β haemolytic Streptococci

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

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

Beta Haemolytic Streptococci Group A Necrotising Fascitis

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

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

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

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

Viruses

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

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

DNA viruses And Associated Diseases

Family Examples Disease Poxviruses Variola Smallpox Herpesviruses Herpes simplex Varicella-zoster Cytomegalovirus Chickenpox Adenoviruses Sore throat, conjunctivitis Hepadnaviruses Hepatitis B Hepatitis Papovaviruses Papilloma JC virus Warts Parvoviruses B19 Erythema infectiosum

Viruses by Electron Microscopy

Varicella Zoster Virus Chicken Pox Shingles Varicella Zoster Virus

Small Pox

And Associated Disease RNA Viruses And Associated Disease

Family Viruses e.g. Diseases Orthomyxoviruses Influenza Paramyxoviruses Parainfluenza Respiratory syncytial Measles, Mumps Respiratory infection Coronaviruses Coronavirus Resp.infection Rabdoviruses Rabies Picornaviruses Polio Caliciviruses Noroviruses Gastroenteritis Togaviruses Rubivirus Rubella Flaviviruses Hepatitis C Hepatitis Bunyaviruses Hantavirus Haemorrhagic fever Retroviruses HIV HIV/AIDS Filoviruses Ebola virus Marburg virus Ebola haemorrhagic fever Marburg haemorrhagic fever Reoviruses Rotavirus Arenaviruses Junin, Lassa viruses

Global status Polio 2003

Noro Virus

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

Viral Replication

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

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

Fungi Structure Classification

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

Yeast-Candida Candida, Gram-stain Streptococci

Candidiasis

Aspergillus fumigatus Moulds-Aspergillus Aspergillus flavus Top Bottom Aspergillus fumigatus

Aspergillus , Microscopic appearance Scanning Electron Microscopy

Mould sinus infection Mould Infections Aspergilloma

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

Never Forget Infection Control! Noro Virus

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