MIC 401 EXAM 1 QUESTIONS WITH VERIFIED ANSWERS LATEST UPDATE 2026

MIC 401 EXAM 1 QUESTIONS WITH VERIFIED ANSWERS LATEST UPDATE 2026 Lecture 2 - Answers Concepts of Infectious Disease Infectious disease - Answers a disease caused by a pathogen true pathogens - Answers an infectious agent that causes disease in any susceptible host Opportunistic pathogen - Answers potentially infectious agents that rarely cause disease in individuals with healthy immune systems. sporadic disease - Answers cases of a disease are isolated infections in given population or region Endemic disease - Answers cases of a disease are routinely detected in given population or region epidemic disease - Answers widespread disease outbreak in particular region during specific time frame pandemic disease - Answers epidemic that has spread to numerous countries Emerging pathogens - Answers ◦ Newly identified pathogens ◦ Pathogens that previously caused only sporadic cases ◦ Examples: Coronavirus (SARS-CoV-2), Zika virus Reemerging pathogens - Answers ◦Infectious agent that was under control, but is now resurfacing ◦ Example: antibiotic resistant strains of bacteria Zoonotic diseases - Answers spread by animals six groups of pathogens - Answers ◦helminth ◦protozoans ◦fungi ◦bacteria ◦viruses ◦prions Helminths - Answers Eukaryotic multicellular animals (parasitic worms) Protozoans - Answers Eukaryotic unicellular parasites ( animal-like protists) Fungi - Answers Eukaryotic unicellular and multicellular organisms Bacteria - Answers prokaryotic unicellular; some are obligate intracellular parasites, while others are free living; usually smaller than eukaryotic cells. Viruses - Answers not cell; infectious particles containing nucleic acids (DNA or RNA genome); usually smaller than prokaryotic cells Prions - Answers infectious proteins( not cells); do not contain DNA or RNA; can cause certain proteins in host brain to fold incorrectly Noncommunicable - Answers not spread person to person Communicable - Answers does transmit person to person ◦ Contagious - easily transmitted from one host to next Active Infection - Answers patient is symptomatic patient is symptomatic - Answers Signs - objective indicators of disease ◦ Measured and verified ◦ Fever, rash, blood in stool Symptoms - sensed by patient, subjective ◦ Pain, fatigue, nausea Latent Infection - Answers host has no signs or symptoms (asymptomatic) Acute vs Chronic Infection - Answers Viral load Vs. Time ◦ Acute- beginning of the time with high viral load. ◦ persistent-latent- beginning of the time with high viral load end with no viral load ◦ persistent- chronic: beginning of the time with high viral load, end with middle viral load. Koch's Postulates of Disease - Answers Four criteria-used to evaluate what pathogen is causative agent of particular disease Four criteria - Answers ◦ 1. Same organism is present in every case of disease ◦ 2. Organism must be isolated from diseased host and grown as pure culture ◦ 3. Organism should cause disease when introduced into susceptible host ◦ 4. Organism must then be re-isolated from new, diseased host Koch's Postulates of Disease- limitation - Answers ◦ Does not apply to noninfectious diseases ◦ Pure culture problem ◦ Obligate intracellular pathogens ◦ Human-only pathogens ◦ Asymptomatic or Latent diseases Infectious Disease Transmission - Answers Reservoir - animate or inanimate habitat where pathogen naturally found Source - disseminates the agent from reservoir to new hosts Infectious Disease - Answers Infectivity - how good an infectious agent is at establishing an infection Virulence - severity of disease following infection Pathogenicity - general ability of agent to cause disease Five Stages of Infectious Disease - Answers 1. incubation period 2. prodromal phase 3. acute phase 4. period of decline 5. convalescent phase incubation period - Answers time between infection and the development of earliest symptoms prodromal phase - Answers early symptoms develop acute phase - Answers the peak of the disease period of decline - Answers replication of the infectious agent is brought under control; symptoms start to resolve convalescent phase - Answers the patient recovers; in some cases the pathogen is kept latent in the patient Epidemiology - Answers "Study of what is upon people" -Describe the nature, cause, and extent of new or existing diseases in a population Epidemiological Triangle - Answers ◦Etiological agent ◦ Host Factors ◦ Environmental Factors Strategies to break the triangle - Answers ◦ Public Education ◦ Quarantine ◦ Vector Control ◦ Role of Public Health System People- clinical setting - Answers ◦Ignaz Semmelweis ◦Joseph Lister ◦Florence Nightingale Ignaz Semmelweis - Answers ◦ Childbed fever - puerperal sepsis ◦ Recommended hand washing Joseph Lister - Answers ◦ Inspired by Semmelweis and Pasteur ◦ Aseptic surgery ◦ Washing instruments with carbolic acid ◦ Encouraged healing, prevented pus formation Florence Nightingale - Answers ◦ Aseptic technique in nursing practices ◦ Founder of modern nursing Healthcare acquired infections (HAIs) - Answers ◦ nosocomial infections ◦ Diseases that develop from healthcare intervention ◦ Hospitals or long-term care facilities ◦ Direct or Indirect contact ◦ Localized or Systemic ◦ Medical devices and procedures ◦ Biofilms ◦ Surveillance, Prevention, and Control programs "Superbug" HAIs - Answers ◦ Drug-resistant pathogens ◦ Routine testing Lecture 3 - Answers Transmission of Infectious Disease Host-Microbe Interactions - Answers ◦Dynamic give-and-take between host and microbes ◦ Can range from benign to causing serious disease Human Microbiota (flora) - Answers ◦Mutualistic ◦ Microbial population associated with human body ◦ Provide nutrients (vitamins) ◦ Compete with pathogens ◦ Promote immune system maturation ◦ Role of Opportunistic pathogens Tropism - Answers Preference of pathogen for specific host (or tissue) Dysbiosis - Answers ◦ Disruption of microbiota ◦ Example: antibiotic treatment Virulence Factors - Answers ways pathogens overcome host defenses Pathogenicity - Answers ability of a microbe to cause disease Virulence - Answers degree (or extent) of disease that a pathogen causes Trade-offs - Answers pathogens that debilitate or kill host quickly may not be well transmitted Attenuated - Answers still infectious, but does not cause disease ◦ Different for immunocompromised hosts ◦ Virulence factors require energy investment Infectious Dose-50 (ID50) - Answers number needed to establish infection in 50% susceptible hosts Lethal Dose-50 (LD50) - Answers amount of toxin needed to kill 50% of untreated affected hosts Toxins - Answers ◦ Molecules that generate adverse host effects in low conc. ◦ Toxigenic organisms ◦ Toxemia - toxin in bloodstream ◦ Can be tougher to destroy than originating organism Endotoxins - Answers ◦ Lipid A region of LPS on Gram-negative cells ◦ Mainly released when cell dies ◦ Fever, chills, body aches, low blood pressure, vomiting, inflammation ◦ Higher levels: septic shock, death ◦ Not readily neutralized ◦ No effective vaccines or therapies Exotoxins - Answers ◦ Toxic, soluble proteins ◦ Made by Gram-negative and -positive bacteria ◦ Often named for organism or type of cells targeted ◦ Examples: neurotoxins, enterotoxins, etc. Type I - Answers Membrane-acting toxins ◦toxin connect to receptor to binds at host plasma membrane to generate a signal that generates effects. Type II - Answers Damage host membranes ◦ toxins disrupt host cell membranes by forming pores or breaking down membrane lipids Type III - Answers Intracellular - AB toxins ◦ 1)binding portion (B) of toxin binds plasma membrane 2). toxin enters cell, often by endocytosis. 3) active portion (A) enters the host cell and exerts an effect. Five Steps to Infection - Answers 1. Pathogen enters host 2. Pathogen must adhere to host tissues 3. Pathogen must invade tissues and obtain nutrients 4. Pathogen must evade host immune defenses in order to replicate 5. Pathogen must be transmitted to a new host 1. Pathogen enters host - Answers ◦Portal of entry ◦ Mucous membranes 2. Pathogen must adhere to host tissues - Answers Initially often nonspecific ◦Adhesins ◦Biofilms Adhesins - Answers 粘附素 ◦ Virulence Factor(s) ◦ Used to stick to host cells (specific or nonspecific) ◦ Make ideal vaccine targets ◦ Examples: Fimbriae, pili, sialic acid binding factors Biofilms - Answers ◦ Bacteria growing as a community on a surface ◦ 60 - 80% human infections originate from them ◦ Implanted devices (catheters, pacemakers, artificial joints) ◦ Dental plaques 斑块 ◦ Often change in virulence factor expression ◦ Quorum 规定人数 sensing 3. Pathogen must invade tissues and obtain nutrients - Answers Stay on surface, pass through cells, or enter cells ◦Invasins ◦Obtaining nutrients ◦Cytopathic Effects Invasins - Answers ◦ Allows pathogen to invade host tissues ◦ Can break down cell-cell junctions, alter host cytoskeleton, etc. ◦ Motility Obtaining nutrients - Answers ◦Siderophores - iron-binding complexes ◦ Various enzymes that break down/scavenge 清除 nutrients Cytopathic Effects - Answers ◦ Damaging or killing of host cells ◦ Not cause of all damage: host immune response 4. Pathogen must evade host immune defenses in order to replicate - Answers ◦Hiding from host defenses ◦Undermine host immune system Hiding from host defenses - Answers ◦ Intracellular pathogens ◦ Latency - ability of pathogen to exist inside a host ◦ Antigen masking, mimicry, variation Antigen masking - Answers pathogen covered in host factors to avoid immune detection Antigen mimicry - Answers pathogen's antigens resemble host molecules, helping it evade immune detection Antigen variation - Answers pathogen switches its antigens, thwarting the mounting immune response Undermine host immune system - Answers ◦ Interference with phagocytosis ◦ Immune suppression Toxins Vs. phagocytes - Answers 1. releasing toxins that kill phagocytes 2. avoiding phagocytosis with a capsule 3. Blocking fusion of lysosome with phagosome 4. Escaping phagosome and living in phagocyctic cell 5. Adapting to harsh environment of phagolysosome or neutralizing hydrolytic enzymes 5.Pathogen must be transmitted to a new host - Answers ◦Cycle can then repeat ◦ Portal of exit ◦ Reservoirs Biosafety Level (BSL) - Answers ◦ Level of infectivity ◦ Extent of disease caused and mortality rates ◦ Mode of transmission ◦ Availability of preventions/treatments for disease BSL 1 and 2 - Answers ◦ Well characterized ◦ Rarely causes disease in healthy people ◦ Human body tissues or fluids 1:no food, hand washing, open lab bench 2:PPE,dengue virus, hepatitis C virus, Salmonella typhi, rabies virus, Zika virus, and HIV ◦open lab, safety cabinet, limit lab access, biohazard signage, easy cleaning, autoclave BSL 3 - Answers ◦ Serious or lethal human disease ◦ Often airborne, may be treatable ◦PPE, monitoring, above, people vaccinated, orgo lab set up, self closing and double door access BSL 4 - Answers ◦ "Exotic" pathogens, extremely dangerous ◦hazardous set up, ebola outfit, lockdown Universal Precautions - Answers guidelines applied when dealing with patients suspected or known have having a blood borne infection ◦ Originated with HIV epidemic in 1980s Standard Precautions - Answers all patients treated as potential source of bloodborne or other infection agents ◦ Expanded universal precautions Lecture 4 - Answers Innate Immunity Innate Immunity - Answers 先天免疫 • Immediate reaction • Non-specific • Limited potency • No memory • composed of physical and chemical barriers, phagocytic leukocytes, dendritic cells, natural killer cells, and plasma proteins. adaptive immunity - Answers 适应性免疫 • Longer to respond • Specific • High potency • Creates memory • Adaptive immune system is composed of B cells and T cells Defense Components of Blood - Answers • Plasma • Defensive blood cells: leukocytes Plasma - Answers • Mostly water + • Electrolytes, dissolved gases, nutrients, proteins • Iron-binding compounds • Complement proteins and antibodies Defensive blood cells: leukocytes - Answers • Erythrocytes ( Carry oxygen and carbon dioxide ) • Platelets (Blood clotting ) • Leukocytes (Defend against invaders ) Phagocytosis - Answers •neutrophil •eosinophil •monocyte Eosinophils - Answers •innate immunity, second line of defense •leukocytes •Account for 5% of the total WBC population • Contain large cytoplasmic granules that stain red-orange • Nucleus is bilobed connected by a thin band • Possess granules containing diverse enzymes and antimicrobial toxins • Exhibit moderate phagocytic activity • Eosinophilia - elevated eosinophil count • (parasites and allergies) •myeloid •phagocytosis Basophils - Answers •Myeloid stem cell •innate immunity, second line of defense •inflammation •leukocytes •1% of WBC population