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Chapter Outline
13.1 We Are Not Alone
A. Contact, Colonization, Infection, Disease
1. Normal (Resident) Flora
2. Pathogens- if the organism causes an infection
B. Resident Microbiota: The Human as a Habitat
1. Normal resident mircobiota
a. Transients
b. Residents
c. Initial colonization begins with the newborn
2. Norma microbiota
a. Microbial antagonism-benefits host, limits pathogens due to
resident microbiota secretions
b. Can become opportunists-harmful to host if the host is
compromised
C. Indigenous Microbiota of Specific Regions
1. Flora of the Human Skin
2. Flora of the Gastrointestinal Tract
a. Flora of the Mouth
b. Flora of the Large Intestine
3. Flora of the Respiratory Tract
4. Flora of the Genitourinary Tract
13.2 Major Factors in the Development of an Infection
A. Pathogenicity
1. True Pathogens
2. Opportunistic Pathogens
B. Becoming Established: Phase One – Portals of Entry
1. Most infectious agents have a preferred portal of entry
a. Skin
b. Mucous membranes
c. Parenteral route
2. The Requirement for an Infectious Dose
a. Infectious dose- ID50
b. Lethal dose-LD50
C. Attaching to the Host: Phase Two
1. Adhesion
a. Fimbriae
b. Capsules
c. Ligands for host receptors(viruses and some bacteria)
D. Invading the Host: PhaseThree
1. Phagocytes and Antiphagocytic Factors
E. How Virulence Factors Contribute to Tissue Damage and Disease
1. Extracellular Enzymes
2. Bacterial Toxins: A Potent Source of Cellular Damage
a. Exotoxin-see Table 3.9
b. Endotoxin
3. Inducing an Injurious Host Response
13.3 The Outcomes of Infection and Disease
A. The Stages of Clinical Infections
1. Incubation Period
2. Prodromal Stage
3. Period of Invasion
4. Convalescent Period
B. Establishment, Spread, and Pathogenic Effects
1. Patterns of Infection
a. Localized
b. Systemic
c. Focal
2. Number of Microbes involved
a. Primary infection
b. Secondary infection
c. Mixed infection
C. Signs and Symptoms: Warning Signals of Disease
1. Sign-objective change that can be measured
2. Symptoms-subjective change that can be felt
3. Syndrome-predictable complex symptoms
4. Signs and Symptoms of Inflammation
a. Edema
b. Granulomas and Abscesses
c. Lymphadenitis
d. Lesion
5. Signs of Infection in the Blood
a. Leukocytosis
b. Leukopenia
c. Septicemia/Bacteremia/Viremia
D. Infections that Remain
1. Latent or long term
2. Sequelae
E. The Portal of Exit: Vacating the Host
13.4 Origins and Transmission of Microbes
A. Reservoirs: Where Pathogens Persist
1. Nonliving
2. Living Reservoirs
a. Carrieri. Human
ii. Asymptomatic, chronic or any stage of clinical infection
b. Animals-zoonosis
c. Vector
i. Biological
ii. Mechanical
B. The Acquisition and Transmission of Infectious Agents
1. Distinctions between Communicable Diseases and
Noncommunicable Diseases
2. Patterns of Transmission in Communicable Diseases
a. Direct Transmission
b. Indirect Transmission
i. Vehicle
ii. Fomite
iii Droplet
C. Nosocomial Infections: The Hospital as a Source of Disease
1. Universal Blood and Body Fluid Precautions-limits nosocomial
infections, protects patients and hospital staff
13.5 Epidemiology: The Study of Disease in Populations
A. Who, When, and Where? Tracking Disease in the Population
1. Epidemiologic Statistics: Frequency of Cases
a. Prevalence vs. Incidence
b. Mortality Rate vs. Morbidity Rate
B. Descriptions of the spread of disease
1. Endemic
2. Epidemic
3. Pandemic
C. Investigative Strategies of the Epidemiologist
1. Clusters of new cases
2. Collect retrospective data
3. Hypothesis of start of this particular outbreak
4. Take steps to curtail outbreak and prevent next outbreak