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Infectious disease & Survey of bacteria
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What are normal microbiota (resident flora) and their benefits?
Normal flora is found in all areas of the human body exposed to the environment (one exception is the lungs), but internal organs and body fluids are considered sterile in a healthy individual
General understanding of the resident flora of various anatomical areas (not specific names of bacteria) and how they may function to protect or to be opportunistic pathogens
(https://bio.libretexts.org/Courses/ManchesterCommunityCollege(MCC)/RemixofOpenstax%3AMicrobiologybyParkerSchneegurtetal/12%3AMicrobialInteractionsFloraPathogenicityandEpidemiology/12.01%3ANormalMicrobiotaofthe_Body)
Infection
occurs when a pathogen or parasite enters and begins to grow on the host
pathogen (primary (frank pathogen) versus opportunistic) (COPs)
A pathogen is any bacterium, virus, fungus, protozoan, or worm (helminth) that causes disease in humans
Primary pathogens are likely to cause disease after infection in a healthy host
Opportunistic pathogens are less likely to cause disease in a healthy host; they often affect immune-compromised hosts
Colonizing opportunistic pathogens (COPs) are microbes that asymptomatically colonize the human body and, when the conditions are right, can cause infections
Virulence
the degree of pathogenicity; describes the level of harm by a pathogen following infection
Infectious dose (ID)
the amount of a pathogen that's required to establish an infection
Lethal dose (LD)
the amount of a pathogen following injection that's required for death
Infectious Disease
a disease caused by a pathogen and may or may not be communicable or contagious to another
Communicable Disease
a disease caused by an infectious agent that is transmissible to another person
Characteristics of virulence (what about the cell itself, or molecules it produces, allow it to cause damage)
Aspects of the pathogen that contribute to virulence:
Reservoirs and Sources - human, animal, inanimate(fomite, food, water, soil)
Reservoir = an animal (including humans) or an environment (soil, water, etc.) that normally harbors the pathogen
Source - where you specifically acquired the pathogen
Carriers - Asymptomatic - Passive, Incubatory, Convalescent, Chronic
Asymptomatic carrier harbors the potential disease agent but does not have the disease
Passive carriers are those who never experience symptoms despite being infected.
Active carriers = actively sick with the infection
Convalescent carriers = recovering from the illness
Incubatory carriers = still in the incubation stage of the infection
Chronic carriers = those who continue to harbor a pathogen for months or even years after their initial infection
Animals: zoonosis and vectors
Zoonotic diseases are infections of animals that can be transmitted to humans
A vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal.
Cycle - Incubation, Prodromal, Invasion (Illness), Convalescence, and comparison between no. of organisms and symptoms
Incubation = This refers to the time elapsed between exposure to a pathogenic organism, and from when symptoms and signs are first apparent
Prodromal = In this phase, the numbers of infectious agents start increasing and the immune system starts reacting to them
Invasion = is characterized by active replication or multiplication of the pathogen and its numbers peak exponentially, quite often in a very short period of time.
Convalescence = the patient recovers gradually and returns to normal
Types of Infections - Local, systemic, mixed, primary and secondary, acute and chronic, asymptomatic
Local infection = an infection that affects only one body part or organ
Systemic infection = affects the entire body
Mixed infection = infected with more than one strain of the same species of bacteria
Primary infection = when you are initially exposed to a pathogen?
Secondary infection = one that occurs when a different infection, known as a primary infection, has made a person more susceptible to disease
Acute infection = symptoms develop and resolve rapidly (i.e. the common cold)
Chronic infection = involves symptoms that develop gradually and resolve slowly
Asymptomatic infection = where a disease or infection does not lead to any (noticeable) symptoms
Sequelae
Pathological consequences that may develop after a disease resolves
Types of Direct and Indirect Transmission, paying particular attention to respiratory droplets, aerosols, droplet nuclei
Adherence and colonization (list a few characteristics that influence)(also associated with virulence)
Adhesins enable the microbiota to attach to host cells
Colonization refers to the ability of the microbe to say attached to the surface and replicate, despite the host defenses
Toxin production - Endotoxins and Exotoxins and comparisons between the 2
Endotoxin = toxin that is not secreted but released after the cell is damaged
Exotoxin = toxin molecule (protein) secreted by a living bacterial cell into the infected tissue
(From one host to the next:) Portals of entry/exit
Fecal-oral: portal is the mucosa of the GI tract
Skin: portal is the skin epithelium
Respiratory: portal is the mucosa of the respiratory tract
Urogenital: portal is the mucosa of the genital and urinary tract
Parenteral: portal is through breaks in the skin
Entry via the eye: portal is conjunctiva (mucous membranes on the eyeball and inner eyelid)
Communicable verses Non-communicable
Communicable = infectious disease
Non-communicable = chronic disease; not passed from person to person
Prevalence
Refers to the total number of cases and reflects the length of the illness, recovery, and deaths
Incidence
The rate of new cases that occur during a specified time period (usually expressed in relation to a population number such as 1000, 10000, or 100000)
morbidity and mortality rates
Morbidity is the rate of illness due to a disease
Mortality is the rate of death due to a disease
Endemic
Endemic disease is one that is always present in a community at a low rate, often in an animal reservoir
Epidemic
Epidemic disease is one in which the number of cases increases in a community in a short time
Pandemic
Pandemic disease is an endemic that spreads worldwide
Enterococcus faecalis and VREs
Staphylococcus aureus
Streptococcus pyogenes
Bacillus cereus
Common airborne and dust borne
Resistant to usual methods of disinfection and antisepsis (b/c of endospores)
Spores survive cooking and reheating
Clostridium botulinum
Clostridium perfringens
Clostridial myonecrosis: muscle tissue is affected
True saprophyte, growing only on dead tissue
Produces toxins
Gastroenteritis
Clostridioides difficile
Listeria monocytogenes
G+ non-spore-forming coccobacilli
Associated with animals and animal products
Causes mild gastroenteritis to more severe cases of meningitis, fetal demise
3rd leading cause of fatalities of food born illness
Foodborne pathogen → causes diarrhea and fever
Streptomyces
Bifidobacterium bifidus
Pioneer colonizer of the human intestinal tract
Associated with vaginal births and breastfeeding
Responsible for many of the significant benefits of breastmilk
Probiotic agent
Mycobacterium tuberculosis (tuberculosis)
Mycobacterium leprae (leprosy)
Bartonella henselae
Rickettsia rickettsia
Rocky Mountain spotted fever
Zoonosis carried by dog and wood ticks (and lice)
First symptoms are fever, chills, headache, and a distinct spotted rash
May damage the heart and CNS
Burkholderia cepacia
active in biodegradation of a variety of substances; opportunistic agent in the respiratory tract, urinary tract, and occasionally skin infections; drug-resistant, numerous outbreaks in consumer products
Neisseria gonorrhoeae
Escherichia coli and Escherichia coli 0157:H7 - STECs
CREs - Carbapenem Resistant Enterobacteraceae
Untreatable and hard-to-treat infections from CRE bacteria are on the rise in patients in medical facilities
Have become resistant to nearly all antibiotics we have today
Almost half of the hospital patients who get bloodstream infections from CRE bacteria die from the infection
Legionella pneumophila
Legionnaire’s disease
Intracellular pathogen
Contaminates various water sources, ranging from lakes to the hot water and air-conditioning distribution systems of large buildings
Causes atypical pneumonia
Fatality rate 3-30%
Pseudomonas aeruginosa
Commonly grows in the soil as a decomposer, but in humans, it can infect surgical wounds or form biofilms in the lungs of cystic fibrosis patients
MDR
Very common HAI
Cause of endocarditis, meningitis, UTIs, abscesses, corneal disease
Opportunistic pathogen
Salmonella enterica
Shigella spp.
Yersinia pestis
Causes a deadly disease (plague) that can be transmitted from animals to humans by an infected flea
Campylobacter jejuni
^^(I did not see anything on C. jejuni specifically*)^^
Vibrio cholerae
Fecal-oral route (contaminated water)
“Rice water stools”
Noninvasive → does not cause fever or bloody stools
Cholera toxin
Vibrio parahaemolyticus
gastroenteritis from rawseafood; symptoms similar to cholera
Vibrio vulnificus
gastroenteritis from rawoysters; serious complications in persons with diabetes or liver disease. Associated with necrotizing fasciitis from swimming in ocean water with an open wound
Bdellovibrio
Treponema pallidum
Leptospira interrogans
Borrelia burgdorferi
Bordetella pertussis
^^(I did not see anything on B. pertussis specifically*)^^
Chlamydia trachomatis
Rhizobium
Bacteroides fragilis
Cyanobacteria (Oxygenic Phototrophic Bacteria)
Anoxygenic Phototrophic Bacteria
Caulobacter
Myxobacteria
Deinococcus radiodurans
Archaea groups - Know Methanogens or any of the others from the table that lists the 5 groups - know 1 and give 3 characteristics
Methanogenic archaea