Microbio Lecture Slides 1.2 PDF

Basic Characteristics of Pathogens WHY DO WE CARE? BASIC CHARACTERISTICS OF PATHOGENS  As future physicians, we care about pathogens because pathogens cause disease & you will be treating diseases  According to the CDC, more than 2.8 million antibiotic-resistant infections occur in the U.S. each...

Basic Characteristics of Pathogens WHY DO WE CARE? BASIC CHARACTERISTICS OF PATHOGENS  As future physicians, we care about pathogens because pathogens cause disease & you will be treating diseases  According to the CDC, more than 2.8 million antibiotic-resistant infections occur in the U.S. each year, and more than 35,000 people die as a result. In addition, 223,900 cases of Clostridioides difficile occurred in 2017 and at least 12,800 people died (CDC, 20202).  2019 Antibiotic Resistance Threat Report (CDC, 2019) lists 21 bacteria & fungi that pose threats to the US (urgent, serious, concerning, watch-list  G4 Swine Flu WHY DO WE CARE? BASIC CHARACTERISTICS OF PATHOGENS  https://www.cdc.gov/respiratory- viruses/data/index.html  https://nextstrain.org/ncov/gisaid/global  https://nextstrain.org/ncov/  https://covariants.org  https://www.fda.gov/food/whole- genome-sequencing-wgs- program/genometrakr-network  https://nextstrain.org/monkeypox/hmpx v1?p=full  https://www.ncbi.nlm.nih.gov/pathogens/  CLASS OBJECTIVES  Identify the three domains of life and what they compose  Compare & contrast prokaryotes & eukaryotes (including cell walls)  Understand pros and cons of being prokaryotic and be able to identify ways in which they adapt and survive  Hint: RON  Identify basic differences amongst different types of bacteria (gram+ vs. gram- vs. acid fast)  Define fungi & distinguish how fungi differ from viruses & bacteria  Define what a parasite is and their basic organizational structure  Be able to identify how viruses are classified PHYLOGENETIC TREE OF LIFE PROKARYOTES VS. EUKARYOTES Bacteria Animals, Plants, Fungi, etc. *Archaea-single-celled, asexual replication, morphologically similar to bacteria, but genes and metabolic pathways more similar to eukarya  THE PROS OF BEING PROKARYOTIC…  Lack of membrane bound nucleus means transcription & translation can be coupled… occurring faster  Binary fission is simpler & faster than mitosis  Small & space saving  High metabolic rates- grow quickly (some double once every 20 minutes) Being small allows microbes to have high metabolic rates = surface-to-volume ratio ↑ as size of cells ↓ Rate of biochemical reactions is limited by diffusion; smaller the cells = diffusion less limiting DID YOU KNOW? THERE ARE 10-100 TRILLION BACTERIA IN THE LARGE INTESTINE… ONLY 7.6 BILLION PEOPLE ON EARTH CONS OF BEING FREE LIVING  With the exception of yeast (has a nucleus=eukaryotic), most unicellular organisms are prokaryotes  3 demands of free-living microbes:  R- Resistance – survive damaging agents  O- Occupancy – habitability of environment  N- Nutrition – intermittent availability of food GOAL: ADAPT & SURVIVE (EFFICIENTLY) TEST YOUR KNOWLEDGE #1  What are 3 differences between prokaryotes & eukaryotes?  Eukaryotes have nucleus, Prokaryotes do not  Prokaryotic DNA is circular, Eukaryotic is linear  No membrane bound organelles in prokaryotes  Prokaryotes reproduce binary fission, eukaryotes reproduce mitosis/meiosis  Prokaryotes are smaller, eukaryotes are bigger  Prokaryotes 70S ribosome, Eukaryotes 80S ribosome  Prokaryotes are haploid, eukaryotes are diploid (or more!) RESISTANCE  Avoid host detection  Develop resistance to environmental threats (i.e. temp, pH, radiation, antibiotics, etc.)  Antibiotic resistant bacteria  MECHANISMS OF SURVIVAL  Cell wall- protect cytoplasmic membrane  Outer membrane- protect cell wall  Bacteria protect their cytoplasmic membrane:  Gram-positive  Gram-negative  Acid-fast  GRAM POSITIVE VS. GRAM NEGATIVE Peptidoglycan Ability of bacteria to retain purple dye & iodine after alcohol challenge (Gram+), if not counterstained with safranin (Gram-) Remember LPS from last class? = Lipopolysaccharide  PEPTIDOGLYCAN NAM NAG  Protects against osmotic pressure  Murein/peptidoglycan shape determines bacterial shape:  Rods (bacilli)  Spheres (cocci)  Helices (spirilla)  Some antibiotics work by inhibiting synthesis of murein/peptidoglycan: penicillins, cephalosporins, & carbapenems (β-lactams) OUTER MEMBRANE & LIPOPOLYSACCHARIDE (LPS) Lipid A (endotoxin)- anchors LPS to outer membrane. Elicits fever in host Core polysaccharide- composed of short series of sugars O-antigen- hydrophilic carbohydrate chains that exclude hydrophobic compounds Hydrophilic compounds can enter cells via specialized porin channels & passive diffusion Larger molecules (B12, iron) translocated in PERIPLASMIC SPACE  Compartment between two membranes  Contains thin murein layer & gel-like solution for facilitating nutrition  Contains degradation enzymes to make impermeable molecules smaller, & binding proteins for transport  Can inactivate β-lactamases, so Gram- bacteria more resistant ACID FAST  Not Gram+ nor Gram-  Cell walls contain waxes  Special stain needed  OCCUPANCY  Habitability of environment (not external agents like antibiotics)  Develop mechanisms to evade common behavior of environment  Movement  For example, developing biofilm to prevent being washed away from gastrointestinal wall OCCUPANCY & MOVEMENT: CAPSULES, FLAGELLA, & PILI  Capsule- slimy outer coating to prevent phagocytosis  Flagella- long, helical filaments for motility (one or more!)  Bacterial chemotaxis- movement towards substances that attract, & away from those that repel  Swimming- all counterclockwise  Tumbling- some counterclockwise, come clockwise  Pili (fimbriae)- attachment of cells to other surfaces  NUTRITION  Is nutrition available for the bacteria?  For example: roughly 20x/day ileocecal valve move nutrient rich contents from small intestine into cecum, intestinal bacteria feed on this, but what happens when the nutrients are gone?! CYTOPLASMIC MEMBRANE & TRANSPORT  Contains permeases to facilitate entry of most metabolites  Facilitated diffusion- substance carried across the membrane down a concentration gradient. Uptake driven by intracellular use  Active transport- movement of molecules across cell membrane into a region of higher concentration, assisted by enzymes. Requires energy  Group translocation- (phosphorylation-linked transport) energy dependent transports certain sugars, which are chemically altered in the process TEST YOUR KNOWLEDGE #2  What are some differences between Gram+ & Gram- bacteria?  Gram+ have teichoic & lipoteichoic acid, thick peptidoglycan cell wall surrounding cell membrane, retain dye- iodine stain after alcohol wash  Gram- have LPS outer membrane outside thin peptidoglycan cell wall that surrounds cell membrane, porin channels for transport, & periplasmic space, do not retain dye-iodine stain after alcohol wash, but retain saponin counterstain (red) WHAT ARE FUNGI AND HOW DO THEY DIFFER FROM BACTERIA? FUNGI (SINGULAR: FUNGUS) ARE A KINGDOM OF USUALLY MULTICELLULAR EUKARYOTIC ORGANISMS THAT ARE HETEROTROPHS (CANNOT MAKE THEIR OWN FOOD) AND HAVE IMPORTANT ROLES IN NUTRIENT CYCLING IN AN ECOSYSTEM. FUNGI REPRODUCE BOTH SEXUALLY AND ASEXUALLY BASICS OF FUNGI  Eukaryotic (Nucleus, mitochondria, Golgi, and endoplasmic reticulum)  Rigid cells walls made of chitin & glucan  Cell membranes contain sterol  Ergosterol (we have cholesterol)  Can be targeted by antifungals  Multiple forms  Unicellular- e.g. “yeast”  Multicellular- e.g. “mold”  Dimorphic- species alternate between yeast & mold forms  Depends on environmental (temp, pH, CO2)  Reproduction- sexual, asexual, or both!  Produce spores, budding, etc.  PARASITES  Parasite- an organism that lives on or in a host organism and gets its food from or at the expense of its host  Two major groups:  Protozoa*- amoebozoa, flagellates, ciliates, and apicomplexa  *some argue about the term, but we’re going to call them protozoa  Animalia:  Helminths- nematodes, cestodes, trematodes  Ectoparasites (Arthropods)- Mites, Lice, Fleas, Ticks, etc.  Ectoparasites: lives outside the host (i.e. flea, tick, etc.) BUT WHAT ABOUT VIRUSES?!  VIRUSES ARE NEITHER PRO NOR EUKARYOTIC BECAUSE THEY AREN’T “LIVING” THINGS CANNOT REPRODUCE BY THEMSELVES VIRUS CLASSIFICATION ALSO A SCIENTIST Dr. Syra Madad, DHSC, MS, MCP - Bachelor of Science degree in Psychology from the University of Maryland - Master of Science degree in Biotechnology with a concentration in Biodefense and Biosecurity - Doctoral degree in Health Science with a concentration in Global Health from Nova Southeastern University  Senior Director, System-wide Special Pathogens Program at New York City Health + Hospitals  Principal Investigator of NYC Health + Hospitals Center for Global Healthcare Preparedness to Special Pathogens  Core Faculty in the National Emerging Special Pathogens Training and Education Center (NETEC) & Assistant Secretary for Preparedness and Response (ASPR)  Assistant Professor in the Graduate Biotechnology/Biodefense Program at the University of Maryland  Netflix’s “Pandemic: How to Prevent an Outbreak” NETFLIX’S “PANDEMIC”  https://www.youtube.com/watch?v=fPs90HZbSVQ  Dr. Syra Madad- https://www.youtube.com/watch?v=nchiJBYxCp8 (not on the exam)