Public Health Microbiology EXAM Review PDF

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Public Health Microbiology - EXAM REVIEW Lecture 1 – Introduction to Nature of Microorganisms Overview · · · · ·

Bacteria, fungi, parasites, viruses and prions Pathogens versus normal flora Organisms in our environment Outbreaks: UK Bovine Spongiform encephalopathy (BSE) 2004, H1N1 Pandemic 2009, Ebola Africa 2014, Bubonic Plague and Smallpox Pathogens: Eukaryotes (Protozoans, Helminths, Yeast, Molds, and Dimorphic yeast)

What is Microbiology · Study of microbes – small microscopic organisms · Living microbes – bacteria, protozoa, fungi · Non-living microbes – prions and viruses Microbes Helping Humans: · Microbes = main forces that drive structure and content of soil, water, atmosphere o Produce Gases (O2 and CO2) – regulate temp of earth · Uses of Microbes by Humans: o Bread production o Alcohol production o Cheese and yogurt production o Antibiotics and vaccines o Clean-up of human-created contamination Microbes Harming Humans · Majority of microorganisms that associate with humans cause harm · HOWEVER: o WHO estimates 10 billion new infections yearly caused by microbes o Infectious diseases – most common cause of death globally o Death toll – 17 million humans globally Why Study Microbiology? · Infectious diseases are a major health problem worldwide · Avoidance of pathogens · Respect normal flora · Breaking chain of infection

Acellular Prions · Bovine spongiform encephalopathy (BSE) · Tiny piece of infected protein · Transmissible, slow progressive and degenerative fatal disease affecting the central nervous system · Heat does NOT destroy prions UK BSE Outbreak · 1986 – Cattle in UK begin to suffer from a condition nicknamed “mad cow disease” due to their behavior · 1989 – UK banned human consumption of certain organ meats (brain and spinal cord) · Early 1990s – British gov insists the disease poses no threat to humans · Mid-1990s – UK bans the feeding of meat and bone meal to animals · January 2004 – 143 people infected with vCJD, 180000 cattle diagnosed with BSE o Disease may take up to 50 years to progress and show Acellular – Viruses · Not alive – active or inactive · Parasitic · Require a live host to replicate · Consist of: nucleic acid surrounded by a protein coat · Viruses infect every type of cell: bacteria, algae, fungi, protozoa, plants and animals · H1N1 – influenzae swine flu; Covid-19 – coronavirus

Viral Components · Capsid: protein shell that surrounds the nucleic acid · Envelope: external covering of the capsid and nucleic acid o Naked viruses do not have envelope · Spikes: found on naked or enveloped viruses o Allow viruses to dock with host cells

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Influenzae virus is single strand RNA with hemagglutinin and neuraminidase spikes. Virus can have drift and shift H1N1. Coronavirus is single strand RNA virus which mutate and change at a high rate. Hemagglutinin spikes and glycoprotein spikes.

Impact of Infectious Disease Influenza · Infectious disease caused by Influenza A or B · Spanish flu pandemic 1918; > 50 million deaths · Canada; seasonal flu kills thousands yearly (very young and very old)

HBV · · ·

Hepatitis B = infectious inflammatory liver disease caused by hepatitis B virus (HBV) Virus transmitted by exposure to infectious blood or body fluids (ex. sexually acquired) Risk of HBV transmission from Carrier = 10-35% o High Risk = healthcare workers o Hepatitis B = 50 to 100 times more infectious than HIV

Viruses and Cancer · 20% of cancers are caused by viruses · Oncoviruses – mammalian viruses capable of initiating tumors Human Pathogens: Eukaryotes · Protozoa, Helminthes and Fungi · True nucleus and cell membrane Protozoa: Eukaryotes · Single cell living and parasitic · Common STD · Cyst (harsh conditions) and trophozoite (infection) · Ex. Malaria, Giardia, Trichomonas Vaginalis Helminths · · · ·

Known as parasitic worms Multicellular Can be seen with the naked eye when mature Group includes: o Tapeworms o Roundworms o Flukes

Helminths – Parasites · Round Worms – large · Flat Worms – large, tapeworms Helminths · · · ·

Digestive parasites Worm-like organism Large, multicellular organisms Find its host through contaminated food, water soil

Fungi: Eukaryotes · Fungal cell walls contain a polysaccharide (chitin) which is not found in any other microorganisms · Fungi caused disease = “mycoses” · Pathogenic fungi cause diseases – range from skin infections to serious systemic infections Clinically Important Fungi · Yeast · Moulds · Dimorphic Fungi Candida Yeast Infections · Normal flora (mucosa, vagina, skin and digestive tract · Example: C. albicans o Premier cause of yeast infections Infections Involving Skin Dermatophytes: Molds Tinea Cruris · Skin infection of the groin · “Jock itch” – generally in males Tinea Pedis · Athletes Foot o Infection results from contact with infected skin scales: showers o Genetic predisposition o Can results in: secondary bacterial infections Dimorphic Fungi · Fungi that have the ability to change btwn yeasts and molds depending on growth conditions · yeasts at body temp (37C) and molds at room temperature (25C) · Responsible for “systemic” mycoses Systemic Mycosis Coccidioides Immitis · Dimorphic Fungi · Most virulent strain · Inhalation of spore · Pulmonary disease – it can disseminate

Human Pathogens: Proka · 10x smaller than eukaryotic cells · Reproduce by binary fission – no nucleus · Cell walls · Classification/Taxonomy – the science of classification of living organisms · Family Genus Species 10x as many microbes in and on body as other body cells. 10 Trillion cells (epithelial, nerve, muscle), 100 trillion microbes.

Bacteria · · · ·

Ubiquitous – found virtually everywhere Microbes that live on us and in us Normal flora as they do not normally cause disease Protection of normal flora is crucial

Microbiology · Some members of our indigenous micro flora are opportunistic pathogens · Opportunistic pathogens – microbes that can cause disease, but generally don’t · Risk Factor – immunocompromised host Microbes and You · Opportunistic Pathogens – Part time danger · Pathogens – full time danger Normal Flora Example · Staphylococcus Epidermidis o Normally harmless part of skin microflora o Forms biofilms on indwelling catheters o Can enter bloodstream – systemic infection

Bad Bacteria · Pathogens – organisms that cause disease · 2 Categories – infectious diseases and microbial intoxications · Staphylococcus aureus is a full-time pathogen

Intoxication · Diseases caused by ingestion of toxin · Fast acting symptoms o Food poisoning – 6 hours o Clostridium Botulinum o Staphylococcus Aureus

Types of Symbiotic Microbe-Host Relationship Mutualism or Parasitism Normal Flora · Benefit to bacteria = have a host and can multiply

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Benefits to human = bacteria may produce vitamins (B and K) that break down food host can’t normally digest o Normal flora – protects host against infection from pathogenic organisms Symbiotic Microbe-Host Relationships · Pathogens harm host · Cost to host can be minimal or fatal

Breakout Week #1 Normal Bacterial Flora Q: When do you think you first acquire normal bacterial flora? We first acquire bacterial flora at the time of birth and from our mothers uterus and vaginal lining. The surface tissues such as skin and mucous membranes are the first to come into contact with bacterial flora as they are in constant contact with environmental organisms. Q: Are bacteria everywhere on your body? Bacteria are present all over the skin that shapes the exterior of the human body. Flu and cold viruses can be transmitted through physical contact as bacteria can reside on skin for long periods of time. Q: Are bacteria everywhere in your body? Yes, bacteria are located in almost every part of the human body such as in the nose and respiratory pathway. The mouth and gut consist of large amounts of bacteria as the mouth is in constant contact with the external environment and the gut assists in the breakdown of food containing bacteria. Q: Is normal bacterial flora ever harmful? Normal bacterial flora is generally harmless however it some cases it can be harmful. For example, bacteria prevent white blood cells from using too much force when fighting infections. This prevents WBCs from functioning at there maximum potential. Q: Should we use antibacterial soap? Antibacterial soaps are said to be no more useful than plain soap and water (FDA). The overuse of antibacterial soaps can even reduce the healthy bacteria on skin as well as remove natural oils leaving skin drier. Therefore, we should not feel so inclined to use these soaps that are marketed as “antibacterial”.

Post Breakout #1: Mosquito Hunter

Why is this a social issue? This is a social issue because the government suffered an economic crisis forcing them to cut funding for water and sanitization. The hierarchy of society plays a role because the higher class can afford water whereas the lower class cannot. The lack of water in Recife affects the level of hygiene of the lower class, as water is a vital part of sustainable health care. Water plays a major part in the success of the agriculture industry. Specifically, in poor areas such as Recife, they rely on agriculture for their nutrition. Therefore, if they have less water to begin with the people as a society are working harder to obtain, store and maintain clean water. Why do you believe people are resistant to fix the issue? The most the citizens can do is monitor their water ensuring it remains closed off. Many are not ready to trust the treatment provided by the government. As for the health workers, they are resistant because the biological larvicide treatment they use is by no means a permanent solution and the issue will arise again. I believe they are aware that in the grand scheme of things, millions are suffering from Zika disease and it is not an issue that can be resolved overnight but requires a greater change to combat. Lecture 2 – Epidemiology Agenda ·

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History of Infectious Diseases o Pioneers in microbiology o Epidemiology terms Chain of Transmission Modes of Transmission

History of Microbiology Miasma Theory · “bad air” – cause of infectious diseases · Replace by the Germ Theory Pioneers in Microbiology Ignaz Semmelweiss · Theory: Autopsy and childbirth don’t mix 1847 · 200 years ago; germ theory wasn’t well known · Hypothesized – medical students carried “cadaver particles” from autopsy to delivery rooms o Caused high death rates of mothers and newborns

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He was ridiculed for this

Pioneers in the Science of Microbiology Robert Koch (1843 – 1910) · German physician – contributed to germ theory of disease · Discovered that Bacillus Anthracis produced spores · Developed methods of fixing and staining bacteria · Developed methods to cultivate bacteria

John Snow · Father of epidemiology · Investigated cholera outbreak in London 1854 · Removed handle of water pump to eliminate a source of contaminated water Epidemiology · Study of patterns, causes, effects of health and disease conditions in populations · Aim to prevent, control or eradicate disease Terms Communicable Disease · Transmitted from person to person · Example: shaking someones hand whilst they sneeze Contagious Disease · Communicable disease that is easily transmitted · Example: Measles (easy to transmit – airborne diseases), chicken pox

Incidence Rates · # of new cases in a defined population during a specific time · Ex. 10 new cases of measles in Canada during 2019 Morbidity Rates · # of new cases in a defined population during a specific time (more specific) · Per 1000, 10000, 100k Prevalence Rates · # of active cases of disease existing during a given moment in time Mortality Rates (death rate): · Ratio of # of deaths of a disease during a specific time period per a population Sporadic Disease · Cases which occur irregularly, haphazardly from time to time and infrequently (ALL outbreaks start this way) Endemic Disease – always present in particular region. Cases fluctuate but never die out. · Lyme disease, measles, gonorrhea, syphilis is endemic to Canada Epidemic · E. Coli O157:H7 = endemic in Canada · Waterborne disease Chain of Transmission · Pathogen – micro-organism which causes disease (gonorrhea) · Virulence – degree of disease that the micro-organism causes o Degree in which pathogen multiplies within a host o Disease-evoking power of a micro-organism Virulence Factors in action: How do Bacteria cause Disease? · Adherence o Adhesions: proteins or glycoproteins on attachment pili (fimbriae) and capsules · Colonization o Growth of microorganisms on host surfaces · Invasion o Ability to invade and grow in host tissues · Destructive Enzymes: o Ex. Hyaluronidase · Toxin Production

Physical (anatomical) Defenses · Physical Barrier – skin · Flushing Mechanisms – urine, sweat, tears, saliva · Antimicrobial Substances o Skin: low pH, high salt o Lysozyme sweat, tears, saliva o Gastrointestinal tract: gastric acid – low pH · Indigenous Microbial (normal bacterial) Flora (most important host defense we have) Interactions Among Pathogens, Host and Environment Whether or not an infection disease occurs is dependent on factors #1 factors pertaining to pathogen · Virulence of the pathogen · # of pathogen needed to cause the infection – infectious doses · Portal of entry #2 factors pertaining to host · Person’s health status · Person’s nutritional status · Lifestyle, socioeconomic level, occupation, travel, hygiene, immune status #3 factors pertaining to the environment · Geographical location; climate, season and temperature · Reservoirs; vectors · Sanitation-adequate waste removal · Availability of portable water

Reservoirs of Infection – site where pathogen can multiply or merely survive until it is transferred to a host · Living Reservoirs o Human Carriers § Typhoid Mary – housekeeper for people (had disease and cured then became carrier of salmonella) o Zoonoses (Animal Carriers) § Diseases transmitted by animals § Dogs, Cats, Birds, Cows, Bats § Arthropods – ticks, mosquitoes, fleas § Referred to as vector transmission · Non-living Reservoirs

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Soil o Ex. Clostridium Perfringens – gas gangrene water o source of gastro intestinal pathogens o ex) E. coli O157:H7 o vibrio cholerae – cholera Food o Chicken, pork, beef, rice o Salmonella, campylobacter, Bacillus

Three Principles Modes of Transmission – Pathogen · Contact Transmission o Indirect or direct · Transmission by Vehicles o Airborne transmission o Ingestion · Transmission by Vectors Contact Transmission · Direct Contact – skin to skin, mucous membrane to mucous membrane (rabies, syphilis, herpes) · Indirect Contact Transmission: Fomites (tetanus, common cold, rusty nail) o Droplet Transmission: sneezing – common cold (whooping cough, pneumonia, common cold) Airborne vs Droplet · Droplet Transmission – indirect contact o If distance travelled < 1 meter · Airborne Transmission – distance travelled > 1m o Vehicle transmission Vector Transmission · Via insects

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Mechanical transmission insect carries pathogen Biological transmission o Pathogen multiplies in insect o Transfer by biting (saliva) OR via feces – bite wounds

Post Lecture #2 Tuberculosis Antimicrobial Multiple Resistance The infectious disease known as tuberculosis exhibits a treatment path unlike other diseases. Primarily, tuberculosis requires the use of “Drug Susceptibility Testing” to identify the presence of drug resistance in a given patient. The various types of tuberculosis such as drug resistant TB and multidrug resistant TB require different forms of treatment. However, even when diagnosed, the treatment itself brings upon many problems including exposure to toxicity, expensive and long treatment periods and the lack of accessibility to these rare drugs. Moreover, tuberculosis exhibits a great level of stress on society due to these factors, potentially leading to the collapse of a health care system. Another factor contributing greatly to the difficult nature of treating tuberculosis is the resistance of drugs. Specifically, forms of the bacterium bacilli causing TB can be resistant to treatment drugs and are selected naturally to become predominant organisms in unproperly treated individuals. Furthermore, wrong prescriptions, ignorance and unawareness of treating tuberculosis, treatment programs that use fake drugs, even healthcare systems and individual physicians who cannot support patients through the lengthy treatment plans contribute significantly to the patient becoming resistant to these drugs. Referring to the podcast, Mario Raviglione believes that investments of more than two billion into tuberculosis research is what will be required to bring this disease to the same level as HIV AIDS. Thus, it should be treated with the same severity as HIV. A lack of investments and funding is another definite reason there are such poor treatment outcomes against tuberculosis. Post Lec #2 Research TB Podcast Research for Post Breakout Assignment #2 Control of TB impaired by Gaps: · Drugs Susceptibility Testing: essential today in precise care of TB, without it we cannot identify the presence of drug resistance in a patient. Performed in small fraction of the total TB cases, only 20% of estimated cases are detected and treated a year. ( 6million cases worldwide 125000 latest treated) Even when discovered, there are problems toxicity, expensive and long treatment of rare drugs, availability of drugs · Impact of TB (public health terms): in society where multidrug TB is frequent stress health industry into collapsing

What factors are contributing to the resistance of drugs for the treatment of Tuberculosis?

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Precise mechanisms for the creation of drug resistant mutants Forms of bacilli that cause tuberculosis that are resistant to drugs they get selected naturally to become predominant organisms in some individuals that are not treated properly o Result of monotherapy meaning treatment with one drug, whether there have been 5 or 6, to which the bacilli (organism) is sensitive o Microbacteria , cause of TB, needs to be treated with 2-3 drugs to which they are sensitive o If the organisms develop resistant to even 1 drug it is likely it will develop the same outcome for all of them o Wrong prescriptions, linked to ignorance or unawareness of how to treat TB, lack of DST doesn’t allow you to make these diagnoses, general national programs that don’t support patients (1-2 years of treatment), programs that use fake drugs o Failure of system or individual physicians that don’t support patients long enough or well enough Lecture 4 - Breaking the Chain of Infection Agenda · Controlling Microbial Growth o In Vitro and in Vivo · Standard Precautions · Environmental Controls Controlling Microbial Growth in Vitro Encourage Microbial Growth in the Laboratory · Enables pathogen identification · Test antimicrobial agents o Culture media o Inoculate specimens to culture media o Incubate until they grow into a visible colony o Perform identification test and antimicrobial susceptibility testing Controlling Microbial Growth in Vitro-Sterilization Inhibit the Growth of Microbes in Vitro Key Terms · Sterilization o Involves destruction of all microbes § Ex. Cells, spores, viruses o Dry heat, autoclaving (steam under pressure) & ethylene oxide gas autoclave in health care o Radiation

Sterilization · Thermal death point – lowest temp needed to kill all the organisms · Thermal death time – length of time needed to sterilize at a specific temperature

Methods of Sterilization Physical Methods · Autoclaves o Most Heat (15 psi, 121C, 15 minutes) · Radiation Ethylene Oxide Autoclave – Sterilization · Low temp process aimed to sterilize instruments that are sensitive to heat and moisture · ETO – colorless gas that is flammable and explosive Controlling Microbial Growth in Vitro – Disinfection Key Terms · Disinfe...