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36 Cards in this Set
- Front
- Back
- 3rd side (hint)
normal (resident) flora |
Microbes that engage in mutual or commensual associations on you |
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infection |
A condition in which pathogenic microbes penetrate host defense, enter tissues, and multiply. |
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Disease |
Any deviation from health, disruption of a tissue or organ. |
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Resident Flora |
-Includes bacteria, fungi, protozoa, viruses and arthropods - Most areas of the body - Large intestine (colon) has largest number - Internal organs, fluids, and tissues microbe-free |
Will be on the exam! |
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microbial antagonism |
Bacterial flora benefit host by preventing overgrowth of harmful microbes. |
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Portals of entry |
Characteristic route a microbe follows to enter the tissues of the body. -skin, gastrointestinal tract, respiratory tract, urogenital tract, transplacental |
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Requirements for an Infectious Dose (ID) |
• Minimum number of microbes required for infection to proceed. • Microbes with small IDs have greater virulence. |
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Adhesion |
microbes gain a stable foothold at the portal of entry; dependent on binding between specific molecules on host and pathogen • examples: fimbrae, flagella, adhesive slimes or capsules, cilia, Suckers, hooks, barbs |
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Surviving Host Defenses |
• The initial response of host defenses comes from phagocytes (WBC). • Antiphagocytic factor: used to avoid phagocytosis • Species of Staphylococcus and streptococcus produce leukodins, toxic to WBCs. • Slime layer or capsule: makes phagocytosis difficult |
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Virulence factors |
severity of disease |
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Toxigenicity |
• Capacity to produce toxins at the site of multiplication. • toxins = poisons -endotoxins: lipid A of Gram- bacteria. -exotoxins: proteins secreted by Gram + and Gram- bacteria. |
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4 Different stages of clinical infections |
1. Incubation period 2. Prodromal stage 3. Period of invasion 4. Convalescent period |
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Patterns of Infections |
• Primary infection • Secondary Infection • Acute infection • Chronic infection |
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Signs vs. symptoms |
• Sign: objective evidence of disease as noted by an observer Examples: fever, septicemia, chest sounds, rash, leukocytosis • Symptoms: Subjective evidence of disease as sensed by patient. Examples: chills, pains, nausea, ache, headache, fatigue
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Signs and symptoms of inflammation |
• Earliest symptoms of disease as a result of the activation of the body defenses. • Signs of inflammation: - edema: accumulation of fluid - granulomas and abscesses: walled-off collections of inflammatory cells and microbes - lymphadenitis: swollen lymph nodes |
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Signs of infection in the blood |
• Changes in the number of circulating white blood cells. - Leukocytosis: increase in white blood cells - leukopenia: decrease in white blood cells - septicemia: microorganisms are multiplying in the blood and present in large numbers. |
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Asymptomatic (subclinical) infections |
Although infected, host shows no signs of disease. |
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Portals of Exit |
• Pathogens depart by a specific avenue; greatly influences the dissemination of infection. - respiratory: mucus, sputum, nasal drainage, saliva - skin scales - fecal exit - urogenital tract - removal of blood |
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Vector |
A live animal (other than human) that transmits an infectious agent from one host to another. • Majority are arthropods - fleas, mosquitoes, flies, and ticks. • Some larger animals can also spread infection - mammals, birds, lower vertebrates. |
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Acquisition and transmission of infectious agents |
• Communicable disease: spreads • Highly communicable disease: contagious, spreads very easily • Non-Communicable: does not arise through transmission from host to host |
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Nosocomial Infections |
• Any disease developed during hospital stay. • Obtained from surgical procedures, equipment, personnel, and exposure to drug-resistant microorganisms. |
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Number of Nosocomial Infections |
• 2 to 4 million cases per year with approx. 90,000 deaths. • 1/3rd of infections can be prevented. |
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Most Common Infection sites of Nosocomial Infections |
1. Urinary tract (39%) 2. Respiratory tract (18%) 3. Surgical incisions (17 %) |
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Epidemiology |
The study of the frequency and distribution of disease and health-related factors in human populations. |
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Endemic |
Steady frequency of disease in a particular area. |
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Epidemic |
When prevalence of disease is increasing beyond what is expected. |
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Pandemic |
Epidemic across the world. |
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Koch's Postulates |
Determining the causative or etiologic agent of infectious disease: - Find evidence of a particular microbe in every case of a disease. - Isolate that microbe from an infected subject and cultivate it artificially in the lab. - Inoculate a susceptible healthy subject with the laboratory isolate and observe the disease. - Reisolate the agent from this subject. |
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Incubation period |
time from contact to first symptoms |
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Prodromal Stage |
Vague feelings of discomfort |
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Period of Invasion |
High levels of microbes causing severe signs and symptoms. |
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Convalescent period |
Symptoms decline, start to feel better. |
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Primary Infection |
initial infection |
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Secondary Infection |
Another infection by a different microbe. |
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Acute Infection |
Comes on rapidly, with severe but short-lived effects. |
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Chronic Infection |
Progress and persist over a long period of time. |
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