Relationships With Microorganisms 2 Flashcards
What is the human microbiome?
Microorganisms on and in human body
How does the human microbiome have a symbiotic relationship with host?
- Production of beneficial microbial products
- Inhibits growth of pathogenic microorganisms
What is infection?
Any situation in which a microorganism gains entry, becomes established and is growing in a host, whether or not the host is yet harmed
What is a disease?
Any situation in which growth of a microorganism, invading pathogen or commensalism results in host damage and production of specific signs or symptoms
STI does not = STD
What is a communicable disease?
Infectious diseases which can be transmitted from one person to another. Transmission may be direct or indirect
What is a non communicable disease?
Most are refferred to as chronic diseases , and are typically a result of genetic, physiological environmental and/or behavioral factors
Give examples of transmissible infections
Influenza, common cold, HIV, gonnorhea
Give examples of non-transmissible infections
Non transmissible infections:
Rabies infection —> rabies virus*
West Nile Virus infection —> West Nile Virus
What are factors that might cause non-communicable diseases?
Genetics
Diet
Environment
Physiological
Behavioral
Give examples of non communicable diseases
Diabetes, HTN, CF, heart attack
What are reservoirs?
The primary /natural habitat where a specific infectious agent lives and multiples
Reservoirs can be:
Living organisms
Non-living sites
Give living organisms which can act as reservoirs
Turtles and reptiles- Salmonella spp.
Domestic animals and animals used for meat - Campylobacter jejuni
Human- Mycobacterium tuberculosis
Give example of non-living sites
Soil- Clostridium tetani
Water- Legionella pneumophilia
What are sources?
The origin from which a susceptible host acquires an infectious agent
What are the types of sources?
Endogenous
Exogenous
Describe a endogenous sources
Host microbiome
Describe exogenous sources
- A person through physical contact or indirectly
- Animals/vectors
- Objects; food, water, doorknobs, medical equipment etc.
- Inanimate injects; fomites- clothes, utensils, furniture
What are carriers?
Individuals capable of transmitting a pathogen without displaying symptoms
What are types of carriers?
Passive and active carriers
What is passive carriers?
Passive carriers- an individual who is contaminated with the infectious pathogen and can mechanically transmit it to another host, without being infected e..g. Poor hand hygiene practices
What is active carriers?
An individual who has been infected with an infectious agent and is able to transmit this agent to others. Active carriers may or may not exhibit signs and symptoms of the infection
What are the types of active carriers?
Incubatory carriers and convalescent carriers
What are incubatory carriers?
Those who can transmit the agent during the incubation period before clinical illness begins
What are convalescent carriers?
Convalescent carriers are those who have recovered from their illness but remain capable of transmitting to others
What are asymptotic carriers?
Active carriers who do not present with any signs or symptoms of the disease despite being infected
Give examples of infections that can be transmitted by asymptotic carriers
- HIV -Human immunodeficiency virus
- HBV -human B Virus
- Neisseria gonorrhea
Give historic examples of asymptotic carriers
Mary Mallon - Typhoid Mary
- 1900 household cook in NYC and NJ
- Asymptomatic carrier of Salmonella typhi
- determined to be responsible for 122 cases of typhoid fever
What are zoonotic infections?
Human are subject to disease that have animal reservoirs. Animals can transmit the infections agent to humans through direct contact
What are iatrogenic infections ?
These are infectious diseases which are contracted as the result of a medical procedure
E.g. A patient treated for a skin wound may acquire necrotizing fasciitis of the bandages or dressings used have not been properly sterilized and are contaminated with Clostridium perfringens or another bacteria
What are nosocomial infections?
These are infectious diseases which are contracted in hospital settings, usually after 48 hours of admission
E.g., A patient at the hospital being treated for coronary artery disease developing symptoms of a respiratory infection- hospital acquired pneumonia
What are the 3 factors that lead to nosocomial infections?
- Transmission of pathogens between health care workers and patients or between patients
- Immunocompromised patients
- Presence of microorganisms in the hospital environment
What is direct transmission?
Infectious pathogens are transmitted from a reservoir/source to a susceptible host by direct contact or droplet spread
What are the types of direct transmission?
- Direct contact transmission
- Droplet transmission
- Vertical transmission
- Horizontal transmission
What is direct contact transmission?
Person to person transmission including sexual contact
Skin to skin/mucosal membranes contact
-impetigo - S. aureus, HSV cold sores- HSV 1, Hand foot mouth disease - Coxsackie virus
Psexual contavt- HSV 2, HIV, HBV, N. gonorrhea, C. trachomatis
How can there be direct contact with environmental source?
Direct contact with environmental source
- Hook worm infection from contaminated soil
- Cutaneous anthrax -Bacillus anthracis
- Brain eating amoeba - N. Fowleri
What is droplet transmission?
Distances of 3Ft or less
- common cold - Rhinovirus - seasonal flu- influenza virus - meningococcal disease- N. Meningitidis
What is vertical Transmission?
Mother to child through placenta
-TORCH infections
What is horizontal transmission?
Mother to child through breast milk
- CMV infection - cytomegalovirus
- HIV
What is indirect transmission ?
Infectious pathogens are transmitted from a reservoir to a host via inanimate objects (vehicles) or animate intermediates
What is Vehicle transmission?
Transmission of pathogen through vehicles; fomites, water, food, air
What are the types of vehicle transmission?
- Fomites
- Water borne transmission
- food borne transmission
- airborne transmission
What are fomites?
Inanimate objects that become contaminated by pathogens (door knob, towel, table cloth)
-objects which are not properly sterilized (medical and/or surgical equipment)
What is water borne transmission?
Fecal -oral GI infections; E. coli, C. jejuni
V. cholera, G. lamblia
What is food borne transmission?
Fecal- oral GI infections
-botulism
What is airborne transmission?
Distances of over 1 meter
- tuberculosis
- Measles
- Chicken pox
What is vector transmission?
Insect vectors carry an infectious agent through purely mechanical means or may support growth or changes in the infectious agent which is then transmitted to a susceptible host
What are biological vectors?
An animal that carries a pathogen that can multiply within their bodies and be delivered to a new host.
- Mosquito -plasmodium spp. Dengue virus, Zika virus, etc
- ticks- R. rickettsia, B. burgdorferi etc.
Fleas- Y pestis
What are mechanical vectors?
An animal that carries the pathogen from host to host without being infected itself
- fly - cockroaches
What are the types of indirect transmission ?
- Vehicle transmission
2. Vector transmission
What are the types of vector transmission?
Bioological and mechanical
Prevention from infectious agents is often…
Multifactoral
How many levels of disease prevention are there?
Primary, secondary and tertiary prevention
What is primary disease prevention?
Measures that prevent the onset of illness or injury before the disease process begins.
- immunization
- vector control
What is secondary disease prevention ?
Measures that lead to early diagnosis and prompt treatment of a disease, illness or injury to prevent more severe problems developing
-screening tests: prenatal TORCH screens
What is tertiary disease prevention?
Measures aimed at treatment/rehabilitation following significant illness. At this level health services workers can work to retain, re-educate and rehabilitate people who have already developed an impairment or disability
What factors lead to a disease? Give an example
Agent (adenovirus/virus) —> source(infected individual, exogenous)—> condition ( poor hygiene, inhalation/direct contact) —> result( upper respiratory tract infection, conjunctivitis )
