Unit 2 Main Groups of Microorganisms PDF

UNIT 2 MAIN GROUPS OF MICRO- ORGANISMS MICROBIOLOGY NURS 1111 1  At the end of the unit, the student will be able to: 1. Review the main groups of Specific micro-organisms of medical importance; Objective 2. List th...

UNIT 2 MAIN GROUPS OF MICRO- ORGANISMS MICROBIOLOGY NURS 1111 1  At the end of the unit, the student will be able to: 1. Review the main groups of Specific micro-organisms of medical importance; Objective 2. List the characteristics of each group of micro-organisms; s: 3. Identify structures that are unique to each group of micro- organisms; 4. Name emerging micro- organisms. 2 Recap: Major classes of Microorganisms Bacteria Viruses Fungi Algae Protozoa 3  MICRO- ORGANISMS CELLULAR EUKARYOTE ACELLUL PROCARYOT S AR ES Algae Bacteria Viruses Protozoa Cyanobacteria Fungi 4  Is defined as the science of biological classification consist of 3 separate but interrelated parts:  Classification Taxonomy  Nomenclature  Identification Once a classification scheme is selected, it is used to group organisms into groups called taxa base on mutual similarity 5 Taxonomy NOMENCLATURE IDENTIFICATION It is the branch of taxonomy The practical side of concerned with the taxonomy which determine if assignment of names to the isolate belongs to the taxonomic groups in recognised taxon agreement with published rules 6 Systematics This term is often use for taxonomy Many taxonomists define systematics as “The scientific studies of organism with the ultimate object of characterizing an arranging them in an orderly manner” It included arranging organism in groups whose members share similar characteristic and reflect as much as possible the biological nature of the organism 7  Bergey’s Manual of Determinative Bacteriology – five volume resource covering all known procaryotes – Classification based on genetic information –phylogenetic – Two domains: Archaea and Bacteria – Five major subgroups with 25 different phyla Bacterial Taxonomy Based on Bergey’s Manual CAROLUS LINNAEUS CAROLUS LINNAEUS In practice the genus and developed the first natural specie of a new prokaryote classification based largely on was determines anatomical characteristics in  phenetic classification the mid 18 th century  Phylogenetic  Genotypic 9  Comparison of the three domains Characteristic Eubacteria Archaea Eucarya Cell type Prokaryote Prokaryote Eukaryote Cell wall Peptidoglycan Varies Varies Membrane Unbranched Branched Unbranched lipids Sensitive to Yes No No antibiotics? Circular Yes Yes No (except in mitochondria and chromosome? chloroplasts) Histones? No Yes Yes  Classification Systems in the Procaryotae 1. Microscopic morphology 2. Macroscopic morphology – colony appearance 3. Physiological / biochemical characteristics 4. Chemical analysis 5. Serological analysis 6. Genetic and molecular analysis G + C base composition DNA analysis using genetic probes Nucleic acid sequencing and rRNA analysis  BACTERIA Smallest living cells (0.1 to 10µm) About 5,000 species known Occur in almost any natural habitat Some species may have many different strains More than 90% either harmless or beneficial to humans Can be grown in artificial culture Characteristics – provides data for identification and classification 12  Unicellular prokaryotic microorganisms with no membrane-bound organelles (lack a true nucleus) Ranging in size 0.5 µ in diameter and 4µ in length Cytoplasmic membrane surrounded by rigid cell wall (peptidoglycan), capsule or slime with flagella, pili/fimbriae Cytoplasm contains 70 S ribosomes, mesosomes, double-stranded DNA chromosome, inclusion bodies Free-living, tiny metabolic factories which synthesize proteins Reproduce asexually by binary fission Nucleoid-single chromosome (long, very condensed DNA molecule in ring form) Plasmids -small, closed-circular, extrachromosomal DNA molecules Typical features of Bacteria 13 TYPICAL BACTERIAL CELL 14 Shapes The presence of rigid cell wall gives definite shape Have a wide variety of shapes Different species of bacteria possess different shapes, and they are classified according to these shapes Mycoplasma spp. lack cell wall therefore they have no definite shape 15 Shapes cont’d Cocci Bacilli (Spherical (Rods) ) Spirochet Vibrio es (Spiral) (curved) Shapes cont’d Shape Classification Example 1. Spherical or oval coccus Streptococcus/ Neisseria spp. 2. Rod bacilli Escherichia coli 3. Comma vibrio Vibrio cholerae 4. Short rods coccobacilli Hemophilus influenzae 5. Flexible spiral spirochetes Treponema pallidum Kannan, I (2016)  Motility Bacteria that are able to ‘swim’ are said to be motile; while those unable to ‘swim’ are nonmotile. This movement is due to the presence of a flagella or axial filament. 18 Bacterial Arrangement Bacilli and cocci may also be classified based arrangement Type of arrangement dependent on plane of division  Most BACTERIA are PARASITES; they get their energy by consuming live Organic Matter as a source of Nutrition. HETEROTROPHS break down materials that they obtain from other Nutrition organisms, such as dead or decaying material. These bacteria are called SAPROPHYTES. and AUTOTROPHS obtain their energy by making their own food from SUNLIGHT OR MINERALS. Growth -Those that use SUNLIGHT as an energy source are called PHOTOAUTOTROPHS -Those that obtain their food from oxidizing inorganic compounds are called CHEMOAUTOTROPHS 20 Nutrition and Growth Nutritional Some bacteria use Also need amino requirement vary glucose as sole acids as nitrogen widely source of carbon source, Some require organic Inorganic ions e.g., compounds in small phosphate, sulphate, quantities ( growth sodium, magnesium, factors) calcium, iron Thiamine, nicotinic acid, folic acid etc. Nutrition & Growth cont’d Bacteria that use oxygen during cellular respiration are called AEROBES. Those that do not use oxygen are called ANAEROBES. (energy is typically obtained through fermentation. OBLIGATE AEROBES are bacteria that cannot live without oxygen. OBLIGATE ANAEROBES - bacteria that CANNOT live in the presence of oxygen. FACULTATIVE ANAEROBES – can use oxygen when it is available, but they do not depend upon it. 22  Nutrition & Growth cont’d Most bacteria grow BEST at a pH of 6.5 to 7.5 – pH affects the rate of enzyme action. Bacteria have varying temperature requirements for growth. – Psychrophilic 15 – 200C – Mesophilic 30 - 370C** – Thermophilic 50 - 600C – Temperature affects the rate of enzyme action and excessive heat denatures the enzymes. **includes most medically important bacteria 23 Reproduction Predominantly asexual by binary fission – Bacterium may undergo fission every 10-20 minutes 24 Bacterial Spores (Endospores) Endospore formation An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria (Firmicute phylum). Are formed at the onset of extremely unfavourable environmental conditions. Metabolically inactive - growth stops, tough wall forms around the dry shrunken cytoplasm, cell ruptures releasing the endospore. Converts back rapidly to a vegetative bacterial cell when favourable growth conditions return. 25 Formation of Endospore DNA is aligned into long filament Duplicate and divide into two, cytoplasmic membrane begins to invaginate DNA completely surrounded by membrane Cortex form and initial spore coat form Mature spore forms The cell wall lyses releasing the endospore 26 Reproducti on Defined as the increase in bacterial cell number Multiply by binary fission Average time taken to double in number- mean generation time Growth can be measured by analysing cell concentration or biomass  Other reproductive methods BACTERIA CAN EXCHANGE GENES BY ONE OF THREE SPECIAL MEANS: CONJUGATION, TRANSFORMATION, OR TRANSDUCTION 1. Conjugation  Part of a chromosome is transferred from donor cell to recipient through pilus  Requires contact between the donor and recipient  Transfer only in one direction 28 CONJUGATIO N Cell to cell contact 29 2. Transformation  Living cell picks up fragments of DNA released by dead cells (Streptococci pneumoniae)  DNA is transferred as “naked” DNA 30 3. Transduction Fragments of DNA carried from one cell to another by viruses 31 VIRUSES Viruses –are simple nucleo-protein complexes which infect and replicate in living cells (parasitic at genetic level) Smallest biological entity Exist throughout nature and can affect plants, humans, animals, birds, insects, rodents, bacteria Ultra-microscopic (10-300 nanometre (nm) – equal to one billionth of a metre (0.000000001 m) Ultra-filterable agents (viruses can pass through a 0.22 micron filter which can retain most bacteria) Have no cell wall, NOT a cell (hence non-living) Some have RNA only, some have DNA only Some are enveloped, some are not 32 Morphology of Viruses Basic Structure of a virus – To reliably visualize them, stains and electron microscopy are needed. – Each virus is a nucleic acid (RNA or DNA) surrounded by a coating, referred to as an envelope or capsid. The shape of a viral coat has implications on how a virus infects a host 33 Morphology of Viruses cont’d The morphological virus types include:  Helical - These viruses are composed of a single type of capsomer stacked around a central axis to form a helical structure, which may have a central cavity, or hollow tube. 34 Morphology of Viruses cont’d  Icosahedral - Most animal viruses are icosahedral or near-spherical with icosahedral symmetry. - All faces are identical. - Larger viruses contain more capsomers 35  Complex - These viruses possess a capsid that is neither purely helical nor purely icosahedral, and that may possess extra structures such as protein tails or a complex outer wall. 36 Nucleic acid contains the genetic material essential for replication.  may be single-stranded or double-stranded  may be linear or circular  may be segmented or non-segmented Capsid  protects the genetic material  provides the structural symmetry of the virus  site of receptors (attachment)  induces antibody production, serves as antigenic determinant 37 Structural Features of a virus Envelope a lipoprotein  derived from the host cell membrane & virus specific protein.  composed of glycoproteins (spikes) -acquired through budding from the host’s cell membrane during maturation.  confers instability to the virus due to loss of infectivity from the disruption or loss of lipid  more sensitive to heat, ultra-violet radiation, detergents and lipid solvents 38 Motility Viruses are not motile they have no structural features for locomotion. Viruses use the skeletal network of the host’s cells to move about. 39 Since viruses are classified as non-living, they cannot: 1. use energy to grow 2. make food 3. take in food 4. produce waste  Viruses do not have their own energy  Rely on energy available within the living cell which they have infected.  However, they do multiply (or replicate) Nutrition and Growth 40 Reproduction?? More Replication  Viruses cannot reproduce or express their genes without the help of a living cell.  Once a virus has "infected" a cell, it will "marshal" the cell's ribosomes, enzymes and much of the cellular machinery to reproduce.  Viral “reproduction” produces many, many progeny, that when complete, leave the host cell to infect other cells in the organism. 41 Viral Replication 1. Absorption or Attachment 2. Penetration 3. Uncoating 4. Transcription 5. Translation 6. Assembly 7. Release 42 Lytic Cycle of Viral Reproduction Lytic cycle  reproduction of viruses using a host cell to manufacture more viruses virus injects nucleic acid into healthy cell  multiple copies are made of the virus’s protein coat and nucleic acid these are then assembled into new viruses the viruses then burst out of the cell destroying it 43 Lysogenic Cycle of Viral Reproduction Lysogenic cycle  involves the incorporation of the viral genome into the host cell genome  Some viruses, such as herpes and HIV, remain latent in the host cells for years.  the function of the cell is unaffected by inclusion of viral nucleic acid, until at some time, it becomes active and breaks away from the host cell’s genetic material.  the host cell is destroyed, and new viruses are released. 45 FUNGI – true fungi are called Mycota or Eumycota All are eukaryotic possess membrane-bound nuclei (containing chromosomes) and a range of membrane-bound cytoplasmic organelles (e.g. mitochondria, vacuoles, endoplasmic reticulum). Most are filamentous composed of individual microscopic filaments called hyphae, which exhibit apical growth and which branch to form a network of hyphae called a mycelium. Some are unicellular - e.g. yeasts. Protoplasm of a hyphae or cell is surrounded by a rigid wall - composed primarily of chitin and glucans, although the walls of some species contain cellulose. All fungi require water and oxygen 46 FUNGI  Many reproduce both sexually and asexually – both sexual and asexual reproduction often result in the production of spores.  All are achlorophyllous – they lack chlorophyll pigments and are incapable of photosynthesis.  All are chemoheterotrophic (chemo-organotrophic) they utilize pre-existing organic sources of carbon in their environment and the energy from chemical reactions to synthesize the organic compounds they require for growth and energy. Possess characteristic range of storage compounds e.g. glycogen, sugar alcohols and lipids. May be free-living or may form intimate relationships with other organisms i.e., parasitic or mutualistic (symbiotic). 47 Morphology of Fungi  Many fungi produce only single cells (unicellular). If they lack flagella, such cells are called yeasts. Saccharomyces yeasts budding 48 Hyphae  Tubular  Hard wall of chitin  Crosswalls may form compartments (± cells)  Multinucleate  Grow at tips 49 50 Motility Nutrition Fungi are non-motile Fungi are heterotrophs that get food and energy from other (they don’t move) organisms Simple fungi produce They secrete digestive motile spores - enzymes into the environment, zoospores then absorb the nutrients released by those enzymes. Most fungi are decomposers: they live on decaying organisms. Some fungi are parasites: they extract food from living organisms. Fungi grow better at a pH of 5, which is too acidic for most bacteria 51  Fungal Reproduction  Fungi reproduce by means of spores  which can be sexual (the products of meiosis) or asexual (the products of mitosis).  Each group of fungi has a unique set of spores.  Asexual reproduction is more common than sexual.  Formed: – Directly on hyphae – Inside sporangia – Fruiting bodies Amanitaa fruiting body Pilobolus sporangiaPenicillium hyphae with conidia 52 ALGAE Simple eukaryotic photosynthetic autotrophs.  Kingdom Protista.  Most are photosynthetic and "simple" because they lack the many distinct cell and organ types found in land plants.  Some algae are microscopically small and consist of only one cell (= unicellular algae), while others are large and are multi-cellular; - the largest algae are brown algae (or kelp) measures up to 70 - 100 feet!  Most are found in the ocean or other bodies of water. Need water for support, reproduction, and nutrition.  Absorb nutrients from the water over entire surface.  Reproduction: All reproduce asexually , some can also reproduce sexually.  Most are not pathogens. A few produce toxins that are harmful to humans. 53 BROWN ALGAE (KELP) 54 Vegetative Structures of multicellular algae  Thallus: Body. Lacks conductive tissue.  Holdfasts: Anchor alga to rock.  Stipes: Hollow, stem- like structures. Does not support weight.  Blades: Leaf-like structures. – Pneumatocyst: Floating, gas-filled bladder. 55 COMPARIS ON OF ALGAE AND PLANT STRUCTUR E 56 Protozoa  Most are microscopic.  They lack a cell wall, unlike plants  They have at least one motile stage in the life cycle.  Most ingest their food.  Asexual reproduction occurs by mitotic division  Some have true sexual reproduction with zygote formation  Can respond to stimuli  All types of nutrition are present: autotrophic, heterotrophic and saprozoic. 57   Many have developed means of locomotion.  They can be aquatic or terrestrial, and free-living, symbiotic or parasitic.  Over 64,000 species are named; half are fossils.  Though unicellular organisms, Protozoa protozoan cell organelles are highly specialized.  They are ecologically diverse, widely dispersed, but many are limited to narrow environmental ranges.  They can be fantastically numerous, forming gigantic ocean soil deposits  They move by pseudopodia, flagella, cilia and they can direct cell movements. 58 Pseudopodia in - AMOEBA 59  CILIA IN - PARAMECI UM 60 SCANNING ELECTRON MICROGRAPH OF A PARAMECIUM 61 FLAGELL A IN - EUGLEN A 62 SCANNING ELECTRON MICROGRAPH OF A EUGLENA 63 MEDICALLY IMPORTANT MICROBES BACTERIA  There are many different bacteria that exist and can cause infection in humans.  However, we shall concentrate on only some of the commonly met forms. 64 65  Staphylococcus aureus  Gram positive bacteria  At lest 40 species  one of the most common causes of human disease.  Most staphylococci colonize the skin and mucous membranes of people without disease. Staphylococ  Is opportunistic, can cause superficial and systemic infections e.g. boils, impetigo and cus  folliculitis. More serious and common infections caused by this organism are pneumonia, bacteremia, and infections of the bone and wounds.  Staphylococcus aureus can also produce toxins that can cause such diverse diseases as food poisoning and toxic shock syndrome. 66  Non-bullous impetigo – pus/fluid forming, itchy, not painful, honey coloured crusts Bullous impetigo – common in children under 2 yrs, fluid-filled blisters, mostly on the arms, legs and trunk, surrounded by red and itchy (but not sore) skin. The blisters may be large or small. After they break, they form yellow scabs 67  Gram positive cocci Catalase and Coagulase positive Methicillin Typically implicated in nosocomial infections, chronically ill patients, multiple course of antibiotics Resistant Increasing incidence in hospitalized Staphylococc patients Typically multiple drug resistant us aureus Staph infections—including those (MRSA) caused by MRSA—can spread in hospitals, other healthcare facilities, and in the community where you live, work, and go to school. (CDC)  Streptococci There are many species of streptococci found normally in the human body. Gram positive cocci Catalase negative Certain strains of streptococci cause some of the most serious diseases in humans. Streptococcus pyogenes (strep group A) is the main cause of bacterial pharyngitis (strep throat) in people. Untreated strep throat can lead to serious sequelae like rheumatic fever (heart valves) and glomerulonephritis (kidneys). Other infections include impetigo and the devastating "flesh eating bacteria" otherwise known as necrotizing fasciitis. – rapid destruction of the soft tissues and muscle. This is a frequently fatal disease and rapid treatment is necessary. 69 Pharyngitis 70  THE There are dozens of different species of gram-negative bacilli, with many species normally found in the intestinal tract. GRAM- In the intestinal tract they have a beneficial effect on the body by preventing overgrowth of potential pathogens. However, if by NEGATIVE surgery or trauma these bacteria get out of the intestine, they can cause serious, life- BACILLI threatening disease. One of the more common gram-negative bacilli that cause disease in humans is Escherichia coli. 71  E. coli is by far the most common cause of uncomplicated community acquired urinary tract infections and is frequently seen in wound infections. GRAM Main cause of gastroenteritis. NEGATIVE BACILLI Salmonella and Shigella are two gram-negative bacilli well known for being causes of food CONT’D poisoning and dysentery, respectively The gram-negative bacilli have been implicated in infections as diverse as pneumonia to ear infections. 72 Escherichia Coli 73 Signs and symptoms include:  Diarrhea, which may range from mild and watery to severe and bloody  Abdominal cramping, pain or tenderness  Nausea and vomiting, in some people  Children present with symptoms more than adults  The bacteria can also spread from one person to another or to objects. 74 Treatment Most people get better in about a week. They often don't see a doctor and don't know that E. coli caused their problems. 75  The majority Neisseria gonorrhoeae is of the cause of the STI Neisseria species gonorrhea. This is a major Neisseria are found normally public health issue worldwide. Untreated – gram in the mouth infections can lead to and gonococcal arthritis and negative female genital pelvic inflammatory disease Neisseria meningitis is the bacteria tract. However, (PID). causative agent of there are meningococcal two meningitis, potentially life- species that can threatening disease of the cause spinal fluid and meninges. very serious disease in 76 Neisseria – diplococci bacteria Neisseria Neisseria meningitis gonorrhoeae 77  VIRUSES – examples of DNA viruses - Parvovirus - Hepadnavirus Herpesvirus Adenovirus Poxvirus Papovavirus 78  Orthomyxovirus Paramyxovirus Rhabdovirus Examples Flavivirus of RNA Picornavirus Viruses Coronavirus Calicivirus Retrovirus 79 Influenza virus – a RNA virus An electron microscopy image of the flu virus. Credits: Rob Ruigrok/ UVHCI. 80  HIV- RNA VIRUS 81 FUNGAL INFECTIONS – The Pathogens Cutaneous infective Subcutaneous infective agents agents Actinomadura madurae Epidermophyton species Cladosporium Microsporum species Madurella grisea Trichophyton species Phialophora Sporothrix schenckii Systemic infective agents Blastomyces dermatitidis Coccidioides immitis Histoplasma capsulatum Paracoccidioides brasiliensis 82 CUTANEOUS MYCOSES - DERMATOPHYTOSES EPIDEMIOLOGY Three genera-Trichophyton, Epidermophyton, Microsporum Anthropophilic-reside on the human skin Zoophilic-reside on the skin of domestic and farm animals Geophilic-reside in the soil Transmission from humans or animals is by infected skin scales 83 CLINICAL SIGNIFICANCE DERMATOPHYTOSES Characterized by itching, scaling skin patches that can become inflamed and weeping Infection in different sites may be due to different organisms but is given one name 84 Tinea pedis (Athlete’s foot) Common organisms are Trichophyton rubrum , Trichophyton mentagrophytes and Epidermophyton floccosum. Initially between the toes spreads to nails, yellow and brittle Secondary bacterial infection Id Reaction (rash spreads to other parts of the body, often the hands and chest.) 85 Tinea corporis ( Ringworm) Epidermophyton floccosum, Trichophyton, Microsporum Advancing annular rings with scaly centre Periphery of ring area of active fungal growth, usually inflamed and vesiculated Non-Hairy areas of trunks mostly 86 Tinea capitis ( scalp ringworm) Trichophyton and Microsporum species Depends on area Small scaling patches to involvement of entire hair with hair loss Microsporum infects hair shafts , Wood`s lamp More common in children due to medium chain fatty acids 87  Samples to be sent for fungal staining and culture Infected skin may be treated with topical application of antifungal Treatment agents miconazole, nystatin and clotrimazole Refractory lesions oral griseofulvin and itraconazole, terbinafine Infections of hair and nails usually require systemic ( oral) therapy 88 SUBCUTANEOUS MYCOSES (dermis, subcutaneous tissues and Bone) Causative organisms reside in the soil and in decaying or live vegetation Almost always acquired through traumatic lacerations or puncture wounds Common among those who work with soil and vegetation and have little protective clothing Not usually transmitted humans to humans Usually confined to tropics and subtropics with exception of Sporotrichosis in USA 89 Systemic infections These occur when fungi get into the bloodstream and generally cause more serious diseases. Systemic fungal infections may be caused either by an opportunistic organism that attacks a person with a weakened immune system, or by an invasive organism that is common in a specific geographic area, histoplasma. Unlike superficial infections, systemic fungal infections can be life-threatening. 90 CANDIDIASIS (candidiosis) Candida albicans and other candida species which are normal flora in the mouth, skin , vagina and intestines C.albicans is dimorphic May occur as a result of overgrowth as suppression of bacteria by antibiotics Manifestations depend on the site e.g. oral candidiasis and vaginal candidiasis and disseminated candidiasis in cancer patients, post GI surgery and AB’s, systemic corticosteroids 91 PROTOZOA Entamoeba histolytica which causes amoebic dysentery. The organism produces protective cysts which pass out of the intestines of the infected host and are ingested by the next host (fecal-oral route). Acanthamoeba can infect the eye, blood, spinal cord, and brain and is transmitted by waterborne cysts picked up while swimming in contaminated water, crossing the mucous membranes. 92  Giardia lamblia can cause a gastrointestinal infection called giardiasis. Cysts pass out of the intestines of the infected host and are ingested by the next host (fecal-oral route). Giardia lamblia in a Fecal Smear 93  Trichomonas vaginalis infects the vagina and the male urinary tract. It does not produce a cysts stage and is usually transmitted by sexual contact. Trichomonas vaginalis in Vaginal Discharge 94 EMERGIN G MICRO- ORGANIS MS 95  New microorganisms capable of causing disease in humans continue to be detected. Whether an emerging microorganism develops into a public health threat depends on factors related to the microorganism and its environment, or the infected human and his/her environment. Such factors include ease of transmission between animals and people and among people, potential for spread beyond the immediate outbreak site, severity of illness, availability of effective tools to prevent and control the outbreak, and ability to treat the disease. 96 SARS Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus (SARS CoV). SARS was first reported in Asia in February 2003. The illness spread to more than two dozen countries in North America, South America, Europe, and Asia before the SARS global outbreak of 2003 was contained. SARS Coronavirus. "Corona" is Latin for "crown" or "halo". You can see the halo-like structures 97  SARS is a contagious disease that typically leads to a potentially fatal form of pneumonia. Experts say that a coronavirus strain which used to only affect small mammals mutated, and then started to infect humans and became human-transmissible (passed from person-to-person). The pandemic was brought under control in July 2003, thanks to close cooperation between affected countries, according to WHO. During that year, all airline passengers travelling from the affected countries were screened at airports. In 2004, a small SARS outbreak was reported in China. However, it was not caused by person-to-person transmission, but as a result of contact with a laboratory virus sample. Unlike smallpox, SARS cannot be eradicated, because it could still be present in animal populations where it could mutate and infect humans. 98 Signs & Symptoms SARS symptoms usually start off like those of the common cold, and gradually become more flu-like. Extreme fatigue (tiredness), malaise (general feeling of being unwell) Headaches Fever - above 38 °C (100.4 °F). According to WHO, this is the only symptom that is common to all patients with SARS Lethargy Confusion Rash Loss of appetite Myalgia - pain in the muscles. Many describe it as an overall feeling of discomfort, and body aches Chills Diarrhea may affect 10% to 20% of patients 99  From 3 to 7 days after exposure, respiratory symptoms develop as infection spreads to the airways and lungs, and may include: Dry cough Runny nose (less common) Sore throat (less common) Shortness of breath (breathing problems) Gradual fall in blood-oxygen level (fatal) Nearly all patients develop pneumonia after about day 7 100 How does SARS spread? An airborne virus - like influenza (flu) and the common cold, SARS is an airborne virus. It spreads in small droplets of water that infected people sneeze or cough into the air. Others breathe the droplets in and become infected themselves. Those most at risk need to be within three feet of somebody who coughs and sneezes. Touching contaminated surfaces - you can also become infected if you touch a surface that an infected person had previously touched, such as a door handle, elevator button or telephone. Infected people who do not wash their hands after going to the toilet (passing stools) can also spread the disease by touch. Good hand hygiene is extremely important in stemming the spread of SARS. Close proximity - people who care for or live with somebody who is infected with SARS are at very high risk of developing the infection. Experts believe that SARS also spreads by other ways that are not yet known. 101  How is SARS diagnosed? There are no rapid screening tests for SARS. In areas where a SARS outbreak is known, the doctor will order lab tests to be done. In areas where there is no known SARS outbreak, the doctor may consider the possibility of SARS if the patient has pneumonia which is confirmed by an X-ray, as well as some other details: - Has the patient recently travelled to an area where there is a SARS outbreak, or known cases of SARS have been reported? - Does the patient work in a place where there might be a risk of exposure to viruses that cause SARS, such as a laboratory -Does the patient have atypical pneumonia without another diagnosis and is part of a cluster of cases? 102 Diagnostic laboratory tests for SARS There are currently three possible diagnostic tests for SARS, however, each has its limitations: -ELISA (enzyme-linked immunosorbent assay) - this test detects SARS antibodies. It is a reliable test, but can only be used 21 days after symptoms started. -Immunofluorescence assay - this test can identify antibodies 10 days after symptoms first appear. However, it is time- and labor-intensive and requires an immunofluorescence microscope and people who know how to use the equipment. -PCR (polymerase chain reaction) test - this test can detect SARS virus genetic material in samples of stools, tissue, sputum and blood. It is a specific but not very sensitive test. Positive test results nearly certainly mean the person has SARS, while a negative test does not completely rule it out. 103 What are the treatment options for SARS? There are no medications which target the SARS coronavirus directly. Supportive - helping the patient breathe and keeping the fever under control with supplemental oxygen and ventilation support as well as antipyretics (medications for fever). Isolation of patient 104 CORONAVIRUS DISEASE (COVID- 19) Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus(RNA) Most people infected experience mild to moderate respiratory illness and recover without requiring special treatment. Others may develop seriously illness and require medical attention. Immunocompromised/ underlying chronic illnesses Prevention; Social distance, proper hand hygiene, wear properly fitted masks. Vaccination The virus can spread from respiratory droplets and aerosols from coughing sneezing etc. self-isolate until you recover if you feel unwell. (WHO, 2021) Signs and symptoms of Covid 19 On average symptoms develop within 5-6 days post infection ( 14 days) Most common symptoms: Fever, cough, tiredness, loss of taste or smell. Less common symptoms: sore throat, headache, aches and pains, diarrhoea, a rash on skin, or discolouration of fingers or toes, red or irritated eyes. Serious symptoms: difficulty breathing or shortness of breath, loss of speech or mobility, or confusion, chest pain. (CDC, 2021) To prevent and to transmission of COVID-19  Get vaccinated when a vaccine is available to you (controversial)  Stay at least 1 metre apart from others  Wear a properly fitted mask  Choose open, well-ventilated spaces over closed ones.  Wash your hands regularly with soap and water or clean them with alcohol- based hand rub.  Cover your mouth and nose when coughing or sneezing.  If you feel unwell, stay home and self-isolate until you recover (WHO, 2021) Influenza Virus H7N9 A bird flu strain of the Influenza virus A. can infect and replicate in a variety of mammals, including humans. first reported to have infected humans in 2013 in China. most of the reported cases of human infection have resulted in severe respiratory illness. does not kill poultry, but can kill humans information is still limited about the full spectrum of illness that infection with avian influenza A(H7N9) virus might cause. 108 Signs & Symptoms Fever cough shortness of breath, which may progress to severe pneumonia Blood poisoning Organ failure 109 How does H7N9 spread? At this point it is not known how persons are becoming infected. Some of the confirmed cases had contact with animals or with environments where animals are housed. The virus has now been found in chickens, ducks, and captive- bred pigeons at live bird markets near locations where cases have been reported. The possibility of an animal source of the infection is being investigated, as is the possibility of person- to-person transmission. The eating of well-cooked poultry and eggs does not transmit the virus Lab Diagnosis real-time reverse-transcriptase–polymerase chain reaction assay viral isolation H7N9 serologic testing using modified hemagglutination- inhibition assays. 110  Treatment options most of the H7N9 strains tested were somewhat sensitive to antiviral drugs effective against the seasonal flu virus. supportive 111 Seasonal (influenza)Flu Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. A year-round disease burden. Most people recover from symptoms within a week without requiring medical attention. Can cause severe illness or death especially with the extreme of age and with reduced immune status Prefers the colder seasons but may be perennial. Seasonal (influenza)Flu Causative agent(s) There are 4 types of seasonal influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease. Influenza A viruses are further classified into subtypes according to the combinations of the hemagglutinin (HA) and the neuraminidase (NA) known to have caused pandemics. subtype currently circulating A(H1N1) and A(H3N2) Influenza B viruses divided into lineages. either B/Yamagata or B/Victoria lineage currently circulating Influenza C virus causes mild infections no public health significance Influenza D viruses affect cattle (WHO, 2021)  SYMPTOMS Sudden onset of fever, Seasonal Dry cough (influenza)F headache, muscle and joint pain, lu severe malaise, sore throat and a runny nose. Seasonal (influenza)Flu Treatment Vaccination esp. at risk individuals Oseltamivir All currently circulating influenza viruses are resistant to adamantane antiviral drugs (such as amantadine and rimantadine) References WHO, 2021, Influenza seasonal. Retrieved from: https://www.who.int/health-topics/influenza-seasonal#tab=tab_2 Kannan, I, (2016) Essential of Microbiology for Nurses WHO (2021) Coronavirus disease. Retrieved from: https://www.who.int/health-topics/coronavirus#tab=tab_1 Tortora, Funke & Case (2020)Microbiology: An Introduction THANK YOU 117