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Test your knowledge on bacteria and viruses, with a focus on Staphylococcus aureus and antibiotic resistance. Learn about common infections, transmission, bacterial structure, viral replication, and more. Find out how to protect yourself against these pathogens.
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Warm Up Staphylococcus aureus commonly causes boils and soft-tissue infections as well as more serious conditions such as pneumonia or bloodstream infections. According to the Centers for Disease Control and Prevention (CDC), 20-35% of adults and children in the United States are positive for the bacteria but do not cause illness. Staphylococcus aureus colonization usually occurs in the armpit, groin, genital area, and, most frequently, the inside of the nose. Most infections occur through direct physical contact of the staph bacteria with a break in the skin (cut or scrape) or during contact with inanimate objects (such as clothing, bed linens, or furniture) soiled with wound drainage. The most common transmission location are in schools and hospitals.
Analyze the graph: 1. Which location has the highest occurrence of resistance? 2. Based on the graph, make an inference about why penicillin resistant S. aureus is greater in one location compared to another. 3. Why did methicillin resistance lag behind penicillin resistance? Based on the trend seen with penicillin, what would you expect to see happen with methicillin?
What do you already know? • What are the differences between viruses and bacteria? • Are all bacteria harmful? • When you get a cold, should you take an antibiotic to help you get better? • What’s the best and easiest thing to do to avoid getting sick?
Bacteria • Bacteriology is the study of bacteria • Bacteria are prokaryotic, unicellular organisms containing DNA and ribosomes. • Bacteria have ALL the characteristics of living things. • Bacteria have the greatest percentageof thebiomass on Earth!
Bacterial Structure • Basic structure of bacteria: Cell membrane Ribosome Cell wall Peptidoglycan* Flagellum DNA Pili
Bacteria • A rather vocal minority (lessthan1%) of bacteria cause disease in humans, animals, and plants. • Bacteria can cause a variety of diseases: • Food Poisoning – Scarlet Fever • Tuberculosis – Whooping Cough • Cholera – Bacterial Meningitis • Syphilis – Pneumonia • Ulcers – Leprosy • Strep Throat – Tetanus VIDEO CLIP: Understanding Bacteria
Viruses • Virology is the study of viruses • Viruses are “biological entities” containing either DNA or RNA that require another cell to survive. • Viruses have some, but not all, of the characteristics of life. *Soareviruses living or non-living?* • Viruses seem to exist only to make more viruses!
Nucleicacidcore (DNA or RNA) Capsid (Protein coat) Viral Structure • All viruses have the same basic structure: Surface Markers
How Do Viruses Work? • In order to replicate and make copies of itself, viruses need a host cell. Any living cell can become a host cell (human, animal, plant, and even bacterial cells!) • Without a host cell, virusescannot function(i.e.-are harmless!) • Although any cell can theoretically become a host cell, specific viruses willonlyinfect specific cells (EX: HIV will only infect human T cells, a part of your immune system)
Transmission of Viruses • Respiratory transmission • Influenza A virus • Fecal-oral transmission • Enterovirus • Blood-borne transmission • Hepatitis B virus • Sexual Transmission • HIV • Animal or insect vectors • Rabies virus
How Do Viruses Work? • Attach: The capsid of the virus binds to receptor proteins on the surface of a host cell, tricking the host cell into thinking it’s not a foreign invader. • Inject: The virus then injects its genetic material (DNA or RNA) into the host cell. • Assemble: The viral genes are expressed, turning the host cell into a virus-making factory. • Repeat: The host cell eventually bursts, releasing the hundreds of newly formed viruses to infect surrounding cells! VIDEO CLIP: How Viruses Work
Viruses • Viruses can cause disease in humans, animals, plants, and even bacteria! • Viruses can cause a variety of diseases: • Common cold – Polio • Hepatitis A, B & C – Influenza • Herpes – Mumps • Mononucleosis – Measles • Warts – Viral Meningitis • Chickenpox – AIDS VIDEO CLIP: Viral Disease
Symptoms Amount of virus Time Virus Acute Virus Infection
Poliovirus Properties of the virus • Enterovirus. • Possesses a RNA genome. • Transmitted by the faecal oral route. • Cause of gastrointestinal illness and poliomyelitis.
Protection • There are a few big ways to protect yourself against pathogens (disease causing agents) • Antibiotics (drugs to kill bacteria) • Antivirals (drugs to treat viruses) • Vaccination (using your body’s own immune system to preemptively guard against attack)
Antibiotics • Antibiotics can only be used to treatbacterial infections! • Target specific structures on bacteria to kill them. • First made from a fungus (penicillin), now most are made artificially. • Unfortunately, antibiotic resistance (where the antibiotic doesn’t kill the target bacteria anymore) is becoming a major problem.
Antivirals • Antivirals can only be used to treat certain viral infections! • Does not “kill” or disarm the virus permanently; only shortens symptoms by 1-2 days. • Usually only prescribed to patients with lifethreateningsymptoms or those that have a greater chance of developingcomplications (because of their age or they have a high-risk medical condition). • Just like antibiotics, there is evidence of antiviral resistance too!
Vaccination • Vaccines can only be used to prevent infections (both viral and bacterial) from leading to disease. • “Trick” your immune system to make antibodies that destroy foreign “bodies” or particles (such as bacteria and viruses). Your body remembers how to make these antibodies when the real thing invades. • Made from a weakenedvirus, inactivatedvirus, or by using only part of the virus/bacteria itself. VIDEO CLIP: Vaccination
To Review.... • What are the differences between viruses and bacteria? • Are all bacteria harmful? Explain. • When you get a cold, should you take an antibiotic to help you get better? Why? • What’s the best and easiest thing to do to avoid getting sick?
Bacteria Virus Both
