Leture #11 Flashcards
What is microbial antagonism?
Resident microbiota prevent pathogen establishment.
Define incubation period.
Time between pathogen encounter and first symptoms.
What factors influence infection susceptibility?
General health, not height or astrological sign.
How are resident microbiota best described?
Mutualistic.
What is the human microbiome?
Total microbes on/in a human; essential for health and functioning.
What does colonization refer to?
Long-term presence of resident microbiota without causing disease.
What is an infection?
Microbes get past host defenses, enter tissues, and multiply.
Define disease.
Deviation from health that results when cumulative effects of infection damage or disrupt tissues and organs.
What is an infectious disease?
A pathologic state caused directly by microorganisms or their products.
What is the Human Microbiome Project (HMP)?
Research since 2007 to characterize healthy microbes and their role in diseases.
How many protein-encoding genes do human cells have?
21,000.
How many protein encoding genes do microbiota have?
Millions.
How many viruses are present per gram of human feces?
10 million.
What can the makeup of one’s intestinal biota influence?
Overall health.
List known sites of microbiota.
- Skin
- Mucous membranes
- Respiratory tract
- GI tract (including mouth)
- Outer portion of urethra
- External genitalia
- Vagina
- External ear canal
- External eye (lids, conjunctiva)
What are newly identified sites for microbiota?
- Lungs (lower respiratory tract)
- Bladder (and urine)
- Breast milk
- Amniotic fluid
- Fetus
What is microbial antagonism?
Resident biota resist displacement by incoming microbes.
What factors weaken host defenses?
- Old age
- Infancy
- Genetic/acquired immunity defects (AIDS)
- Surgery and organ transplant
- Physical and mental stress
- Pregnancy
- Underlying diseases
- Chemotherapy/immunosuppressive drug.
What is the role of the placenta in microbiota acquisition?
Harbors small but significant bacteria.
What is the primary source of microbiota for a newborn?
Its trip through the vagina.
What does adhesion refer to?
Process by which microbes gain a more stable foothold on host tissue.
What are adhesion mechanisms used by pathogens?
- Fimbriae (pili)
- Surface proteins
- Adhesive slimes or capsules.
What are exoenzymes?
Enzymes secreted by microbes that break down and inflict damage on tissues.
What is a toxin?
A specific chemical product of microbes that is poisonous to other organisms.
What is the definition of zoonosis?
Animal-origin infections transmissible to humans.
What is the difference between direct and indirect transmission?
- Direct: close contact between people
- Indirect: an object or substance carries the agent from one person to another.
What is a healthcare-associated infection (HAI)?
Infectious disease acquired or developed during a hospital or health care facility stay.
What are common pathogens associated with HAIs?
- C. difficile
- S. aureus
- Klebsiella
- E. coli
- Enterococcus.
What are the signs of infection in the blood?
- Leukocytosis: increase in white blood cell levels
- Leukopenia: decrease in white blood cell levels
- Septicemia: microorganisms multiplying in the blood.
What characterizes a localized infection?
Confined to specific tissue.
What is a focal infection?
Spread from a local site.
What is the definition of virulence?
Severity of disease; determined by ability to establish and cause damage.
What is the infectious dose (ID)?
Minimum number of microbes needed to cause infection.
What is meant by the term asymptomatic infection?
No noticeable symptoms are produced.
What is latency in terms of infections?
A dormant state of microbes in certain chronic infectious diseases.
What are sequelae?
Long-term or permanent damage to tissues or organs caused by infectious disease.
What is the prodromal stage?
1 to 2 day period when the earliest notable symptoms of infection appear.
What is the acute phase of infection?
Infectious agent multiplies at high levels, exhibits its greatest virulence.
What occurs during the convalescent period?
Patient begins to respond to the infection and symptoms decline.
What is a primary reservoir for pathogens?
Primary habitat of pathogens (humans, animals, soil, water).
What is a carrier in the context of infections?
An individual who inconspicuously shelters a pathogen and spreads it to others.
What are common living reservoirs for infections?
- Humans
- Animals (e.g., mammals, birds, lizards).
What is the difference between mechanical and biological vectors?
- Mechanical vector: insects carry microbes to host on their body parts
- Biological vector: insect injects microbes into host.
What are common pathogens associated with healthcare-associated infections (HAIs)?
C. difficile, S. aureus, Klebsiella, E. coli, Enterococcus
These pathogens are frequently responsible for infections acquired in healthcare settings.
What are key control measures for preventing HAIs?
Infection control officers, aseptic techniques, universal precautions
These practices help minimize the risk of infection transmission in healthcare environments.
What circumstances make healthcare-associated infections unavoidable?
Compromised patients, collection point for pathogens, lowered defenses, infections from fomites, medical equipment, other patients, medical personnel, visitors, air, and water
These factors increase vulnerability to infections in healthcare settings.
What healthcare processes lead to healthcare-associated infections?
Treatments using reusable instruments, indwelling devices, high proportion of hospital population on antimicrobial therapy
These processes increase the likelihood of infectious agent transfer.
What are the most common healthcare-associated infections?
Pneumonia, gastrointestinal illness, urinary tract infections, bloodstream infections, surgical site infections
These infections are prevalent in healthcare settings.
What are five common hospital pathogens?
- Clostridioides difficile: GI infections
- Staphylococcus aureus: pneumonia, surgical site infections, bloodstream infections
- Klebsiella species: surgical site infections, urinary tract infections, pneumonia
- Escherichia coli: urinary tract infections, surgical site infections, bloodstream infections
- Enterococcus species: surgical site infections, urinary tract infections, bloodstream infections
These pathogens are frequently isolated in clinical infections.
What is the role of an infection control officer?
Implements proper practices, tracks outbreaks, identifies breaches in asepsis, trains healthcare workers
This role is crucial for maintaining infection control standards in healthcare facilities.
What is Koch’s Postulates?
A series of proofs for determining causation of infectious disease
These postulates help establish a causal relationship between pathogens and diseases.
List the steps of Koch’s Postulates.
- Evidence of microbe in every case
- Isolate and cultivate microbe
- Inoculate healthy subject and observe disease
- Reisolate same microbe
These steps are foundational in microbiological research.
What are exceptions to Koch’s Postulates?
- Some agents cannot be isolated or grown in the lab
- Causation cannot be determined in polymicrobial diseases
- Some infections cannot be elicited in animals
These exceptions highlight limitations in traditional methods of establishing causation.
Define epidemiology.
Study of disease frequency/distribution in populations
Epidemiology encompasses various disciplines to understand health trends.
What are key terms in epidemiology?
- Prevalence: Total existing cases
- Incidence: New cases over a certain period
- Mortality rate: Deaths due to disease
- Morbidity rate: Number of persons afflicted
- Endemic: Steady frequency in a locale
- Epidemic: Increase beyond expected levels
- Pandemic: Spread across continents
Understanding these terms is essential for analyzing disease patterns.
What is a common-source epidemic?
Results from common exposure to a single source of infection over time
This type of epidemic illustrates how a single point of exposure can lead to widespread infection.
What is the role of an epidemiologist?
Identify causative agents, track behaviors, collect clues on pathology, track disease distribution
Epidemiologists play a critical role in public health by monitoring and analyzing disease patterns.
What are reportable or notifiable diseases?
Certain diseases must be reported to authorities; others are reported voluntarily
This reporting system helps track and control infectious disease outbreaks.
Who was Florence Nightingale?
Revolutionized epidemiology with sanitation practices, kept meticulous notes on disease and mortality
Her contributions laid the groundwork for modern nursing and public health practices.
