Medical Microbiology Quiz

Course Information

• Course Title: NUR1016 Microbiology and Pharmacology
• Semester: 2
• Academic Year: 2024/2025
• Lecture: L01
• Date: Jan 2025
• Instructor: Sony SO

Introduction to Microbiology

• An individual living thing, such as an animal or plant, is called an organism.

Classification and Structures of Microorganisms

• Microbiology is the study of all living organisms too small to be seen with the naked eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa, and algae, which are collectively known as microbes or microorganisms.
• Different branches of Microbiology exist including: Pharmaceutical Microbiology, Food Microbiology, Industrial Microbiology, Agricultural Microbiology, Molecular Microbiology, and Marine Microbiology.
• Medical microbiology is the study of pathogenic microbes, their role in human illness and diseases. This also includes the study of microbial pathogenesis, epidemiology, disease pathology, and immunology.
• Clinical microbiologists oversee prevention, diagnosis, and treatment of diseases. They will also diagnose viral infections and monitor patients following treatment.
• Virologists diagnose viral infections and research the effectiveness of antiviral drugs.
• Parasitologists research parasites and their biology and associated pathologies.

Emerging and Re-emerging Infectious Diseases

• Historical outbreaks of infectious diseases are presented in the given images including Plague (1894), Hong Kong Flu (1968), Avian Flu (1997), SARS (2003), Swine Flu (2009), 2019 Coronavirus Disease (COVID-19), Ebola, Middle East Respiratory Syndrome (MERS), Zika Virus.
• Prevention and control measures were addressed for all diseases including: Personal hygiene, environmental hygiene, and travel health advice.

Microbiology

• This is the study of all micro-organisms.
• Different types of microbes studied include: bacteria, archaea, viruses, fungi, prions, protozoa, and algae.

Scientific Committees

• The Center for Health Protection (CHP) has set up scientific committees.
• Committees are designed as a platform to deliberate and facilitate professional exchanges amongst experts. They provide strategies and actions for communicable disease control and prevention.
• Six specific committees are mentioned: AIDS and STIs, Emerging & Zoontoic Diseases, Enteric Infections and Foodborne Diseases, Infection Control, Vaccine-Preventable Diseases, and Vector-borne Diseases.
• Chairpersons of each committee are mentioned.

Role of Clinical Microbiologists

• Clinical microbiologists at the Queen Mary Hospital analyzed consultations from February 1995.
• Fifty-three percent of cases involved patients with persistent fever despite multiple antibiotic therapies.
• Gram-positive, gram-negative bacteria, and fungi were found in 39%, 31%, and 19% of consultations, respectively.
• Most consultations (55%) involved surgical units.

Host-Agent-Environment Model

• This model depicts the relationship between the host (susceptible hosts), microbe (pathogens), and the environment (community/contaminated environment/ventilation).

Three Domains of Life / Six Kingdoms of Life

• There are three domains of life: Bacteria, Archaea, and Eukarya.
• The domains are further subdivided into six kingdoms: Bacteria, Archaea, Protista, Plantae, Fungi and Animalia, which represent different classifications of life on Earth.

Prokaryotes, Eukaryotes VS Viruses

• Prokaryotes are single-celled organisms without a nucleus or membrane-bound organelles. Bacteria are prokaryotes.
• Eukaryotes are single-celled or multicellular organisms with a nucleus and membrane-bound organelles. This includes humans, fungi, and protists.
• Viruses are not cellular organisms, consisting of genetic material (DNA or RNA) and proteins. They are not considered living organisms outside of a host cell.

Three Domains of Life - Archaea

• Archaea can survive in extreme environments.
• Different types of Archaea include: Psychrophile Archaea (cold-loving), Halophile Archaea (salt-loving), and Thermophile Archaea (heat-loving archaea).
• Methanogens are organisms that produce methane in anaerobic conditions.

Three Domains of Life - Eukarya

• The Kingdom Protista is a group that contains mostly single-celled eukaryotic organisms, which aren't categorized as plants, animals, or fungi.
• Some protists exhibit autotrophic feeding methods (photosynthesis), heterotrophic feeding (consuming other organisms), or a combination (mixotrophic feeding).

Multicellular & Unicellular

• Multicellular organisms consist of numerous cells organized into tissues, organs, and organ systems. Eukaryotes.
• Unicellular organisms consist of a single cell. Prokaryotes.

Six Kingdoms of Life

• Eubacteria, Archaebacteria, Protista, Plantae, Fungi, Animalia are the six kingdoms of life on Earth. Based on shared evolutionary history.

Microbes or Not Microbes; Living or Non

• The definition of "living" and criteria for life are subject to debate.
• Microbes can include viruses, protozoa, fungi, helminths, bacteria, and archaea.
• Prions are problematic to classify as living or non-living.

Viruses

• Viruses are not cellular and require a host to reproduce
• Lack metabolic machinery and autonomous reproduction.

Bovine Spongiform Encephalopathy

• Also called Mad Cow Disease.
• BSE is a neurodegenerative disease in cattle caused by the accumulation of abnormal protein called prions (protein that trigger normal proteins in the brain to fold abnormally) in nervous system.
• BSE is zoonotic because of epidemiologic links with variant Creutzfeldt-Jakob Disease (vCJD) in humans, leading to dementia and death.

Insect and medical diseases

• Insects, like mites and lice can cause serious medical diseases including Scabies and Head Lice.

Taxonomy and Nomenclature

• Taxonomy is the science of naming, describing, and classifying microbes.
• The hierarchical structure includes Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. The rules of taxonomy are defined by the ICNP (International Code of Nomenclature of Prokaryotes).
• Bacteria (E. coli), strains, variants and subvariants are classified

Serotype

• Serotype describes the classification of bacteria based on surface antigens (like O and H antigens).
• Different types of serotypes like EHEC, ETEC, EPEC, EAEC, and EIEC cause E. coli infections.

Nomenclature - Variety

• Variety is a taxonomic rank, below species and subspecies, but above form. Examples include: Sarcoptes scabiei var. hominis (infects humans) and Sarcoptes scabiei var. canis (infects dogs).

Nomenclature in Virus Taxonomy

• Viruses are classified using a similar hierarchical structure.
• Example: the family Filoviridae includes the genus Orthoebolavirus; members of this genus can be seen in numerous diseases.

Hemagglutinin (HA) And Neuraminidase (NA)

• Influenza A viruses are categorized based on two proteins, Hemagglutinin (HA), and Neuraminidase (NA) to determine viral subtypes.

Influenza Virus Nomenclature

• Influenza viruses are named based on their type, place of isolation, sample number, year of collection and subtype

Medical Parasitology

• This is the study of parasitic organisms.

Simple/Complex Life Cycles of Parasites

• Some parasites have a simple life cycle involving just one host, whereas others require multiple hosts to complete their life cycle.

Ecto/Endoparasites

• Ectoparasites live on the outside of a host (e.g., ticks, mites, lice)
• Endoparasites live inside a host (e.g., Trichomonas vaginalis, Plasmodium spp.)

Host-Parasite Relationships

• Obligate parasites depend entirely on a host.
• Facultative parasites can survive without a host, but may adopt a parasitic lifestyle if conditions are favorable.
• Accidental parasites might survive in an unusual host.

Oral Myiasis

• Oral myiasis is the invasion of fly larvae in the oral cavity.

Symbiosis

• Mutualism is a symbiotic relationship where both organisms benefit.
• Commensalism is a symbiotic relationship where one organism benefits and the other is unaffected.
• Parasitism is a symbiotic relationship where one organism benefits and the other is harmed.

Microbes – Size in Micron

• The size of microbes is measured in microns (µm).
• Microscopic organisms appear to be of varying sizes depending on whether a light microscope, SEM(Scanning Electron Microscope)or a 3D image is used.

Microbes Classification

• Phenotypic classification is based on observable characteristics (like shape, size, and behavior of microbes).
• Genotypic classification involves DNA analysis for classification.

Microscopic Techniques

• Bright-field microscopy and electron microscopy are used to view microbes. These allow for visualization of the structure and components of microorganisms based on differences in the types of light used.

Viral Structure

• Viruses are described by viral genome (either RNA or DNA), Capsid, Spike Protein.

Bacterial Structure

• Microbes such as Bacteria have components such as the Capsule. Cell Wall, Plasma Membrane, Cytoplasm, inclusion, Ribosomes, Fimbriae, Plasmids, Flagellum/Flagella, Pillus, and Mesosome.

Fungal Structure

• Fungi are eukaryotic organisms.
• The cell walls of fungi are made of chitin.

Protozoa

• Protozoa are eukaryotic organisms that are unicellular and can be either free-living or parasitic.
• Protozoa are mostly microscopic and move with structures such as pseudopods, flagella, or cilia.

Algal Structure

• Algae are photosynthetic, eukaryotic organisms, often referred to as plant-like protists.
• Algae can be found in various aquatic and some terrestrial habitats, and are responsible for a substantial portion of global oxygen production.

Algal Blooms

• Algal blooms are characterized by increased growth of algae within a water body.
• Algal blooms can produce various types of harmful toxins, which may pose threats to human and animal health.

Reproduction of Microbes

• Methods of bacterial reproduction include binary fission, budding, and sporulation (for some fungi and certain bacteria.
• Spores provide the means of propagation and continuation of a species.

Helminth

• Multicellular eukaryotic invertebrate parasitic worms are often classified as helminths.
• These worms can be microscopic when they are eggs, whereas the adults are visible to the naked eye.
• Helminths are known to cause health problems such as Helminthiasis in humans and animals.

Medically Important Helminths

• Various types of helminths are described, such as Roundworms, Pinworms, Hookworms, Tapeworms, and Liver flukes.

Clonorchiasis

• Clonorchiasis is a parasitic infection of the liver due to the presence of the fluke Clonorchis sinensis.

Biofilms

• Biofilms are colonies of microbes in a complex community that are attached to hard surfaces.
• Biofilms protect bacteria from harmful conditions and external factors like antibiotics.

Population Growth Curve

• The population growth rate of bacteria varies based on several factors including space availability, nutrient sufficiency and waste disposal.

Growth Curve Phases

• Lag Phase - initial phase where microbes adapt to the new environment, not yet reaching maximum growth rate.
• Exponential growth phase (log phase) - The population multiplies rapidly, and cells reach maximum growth rate
• Stationary phase - Division rate slows as nutrients and resources become limited and waste products accumulate.
• Death phase - The population begins to die at an exponential rate as nutrients are depleted and/or toxins have built up.

Microbial Growth Factors

• Temperatures (minimal-maximum) for bacterial growth
• Optimal temperature for microbial growth
• Nutritional factors (nutrient availability, fastidiousness)
• pH (acidophilic-alkaliphlic)
• Oxygen Requirements (obligate aerobe - obligate anaerobe, facultative anaerobe - aerotolerant anaerobes, microaerophiles)
• Osmotic Pressure (non-halophilic - halophilic)