Introduction to Microbiology MC Spring 2025 PDF

WE MAKE DOCTORS Introduction to Microbiology Arturo Ochoa, M.D.  Recognize and differentiate a true pathogen vs a non- Identify the...

WE MAKE DOCTORS Introduction to Microbiology Arturo Ochoa, M.D.  Recognize and differentiate a true pathogen vs a non- Identify the infective pathogen Compare and difference identify the between different prokaryotes and characteristics of eukaryotes bacteria, prions, organisms virus, fungi, and parasites Outline the general characteristics of pathogenesis: Adherence Evasion of innate and acquired immune response Penetration and spread, metabolic needs Injury mediated by the immune response Microbiology Dutch biologist Anton van Leeuwenhoek in 1674 peered through his ground microscopic lenses at a drop of water and discovered a world of million of tiny “animacules” Almost 100 years later, Danish biologist Otto Müller organized bacteria into genera and species according to classification methods of Carolus Linnaeus Microbiology Thousands of scientists have followed these pioneers, each building on the foundation established by his or her predecessors Each added an observation that expanded our understanding of microbes and their role in disease Eukaryotes Present in humans, protozoa, animals, and plants DNA located in nucleus and stored in several chromosomes and contains histones Present mitochondria and 80S ribosomes A cell membrane of a lipid bilayer in plants, fungi, and algae Prokaryotes Present in bacteria and archaea DNA in cytoplasm due to lack of nucleus and stored in circular bacterial chromosome and plasmids Absent mitochondria with 70S ribosomes and two subunits 50S and 30S A cell membrane of a lipid bilayer present in most bacteria Image: AMBOSS. (2024) The Cell of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/Lo0wcS?q=prokaryote#Zefdbdc5626333bb72710d70a12e18d57 Pathogens True pathogens and Non-Infective Pathogens/Opportunistic True Pathogens: Are always capable of causing disease in healthy individuals Can infect individuals with a normal immune system Possess specialized mechanisms to invade, evade or damage host tissues Often exhibit specificity for certain tissues or organs Pathogens Non-Infective Pathogens/Opportunistic: Usually harmless, but can cause disease in immunocompromised hosts Typically require a weakened or altered immune response to cause infection Lack or have minimal virulence factors May proliferate in various tissues Bacteria Bacteria constitute a domain of unicellular prokaryotes that don’t have a nucleus. They can be considered facultative and obligate pathogens Classified by their structures as gram +/- Possess a variety of forms such as: bacillus, cocci, coccobacilli, and spirochetes They can be aerobic or anaerobic Some bacteria can be hemolytic Bacteria They are enzyme producers which have different mechanisms of action They are toxin producers: Endotoxins and Exotoxins Some bacteria are associated with oncogenesis Virus Obligate intracellular parasite, virion formers DNA viruses Double stranded DNA (dsDNA) Single stranded DNA (ssDNA) RNA viruses Double stranded RNA (dsRNA) Single stranded RNA (ssRNA) Virus Smallest infectious particles, ranging in diameter from 18 to 600 nm They affect the host by either RNA or DNA replication inside host cells through different mechanisms Some viruses are known to be involved in oncogenesis Parasites Symbiotic organisms that live on or in larger organisms to feed and live, causing harm in the process They can be classified by location, class, host dependence, and size Some of them use hosts to carry out transmission, and some may use vectors Prions Misfolded proteins with an increase beta-sheet structure Involved in neurological diseases Small size Lack of nucleic acid genome Fungi Eukaryotes that occupy their own kingdom Mycoses are infections cause by fungi Most are obligate or facultative aerobes They can reproduce sexually, asexually, or both They synthetize metabolites both primary and secondary Pathogenesis Microorganisms faced with antimicrobial defenses of the host species have evolved and developed a variety of characteristics that enable them to bypass or overcome these defenses and carry out their obligatory steps for survival. Pathogenesis Obligatory steps: Attachment and entry to the body Local or general spread into the body Multiplication Evasion of host defenses Shedding from body Cause damage in host Pathogenesis Mechanical and other barriers: Surface molecule on microbe attaches to receptor molecule on host epithelial cell Produce ciliotoxic/ciliostatic molecule Fusion protein in viral envelope Microbial enzymes mediate cell penetration Phagocytic and immediate host defenses Microbial outer wall or capsule impedes phagocytosis Sulphatides of Mycobacterium tuberculosis inhibit fusion Exit from phagosome into cytoplasm Production of an elastase Pathogenesis Phagocytic and Immediate host defenses Core antigen of hepatitis B suppresses IFNβ production Prevent activation of IFN induced enzymes Immune defenses Bacterium produces IgA protease Virus envelope molecule binds to CD4 on helper T-cell surface Switch on different surface antigens Mutation, genetic recombination Richard, Goering., Dockrell, Hazel., Zuckerman, Mark., Chiodini, Peter.(2024) Mims' Medical Microbiology and Immunology, Elsevier. 7th Ed. Chapter 13, pages 110-116, Retrieved from ClinicalKey Host-Parasite Relationship Every infection is a race between the capacity of the microorganism to multiply, spread, and cause disease; and the ability of the host to control and terminate infection Infecting microorganisms can gain entry to a healthy host by: Specific mechanisms for attaching to, or penetrating, the body surfaces Introduces by biting arthropods Introduced via skin wounds or animal bites Richard, Goering., Dockrell, Hazel., Zuckerman, Mark., Chiodini, Peter.(2024) Mims' Medical Microbiology and Immunology, Elsevier. 7th Ed. Chapter 17, pages 160- 175, Retrieved from ClinicalKey References Richard, Goering., Dockrell, Hazel., Zuckerman, Mark., Chiodini, Peter.(2024) Mims' Medical Microbiology and Immunology, Elsevier. 7th Ed. Chapter 13, 17, pages 110-116, 160- 175.