chapter 13 Flashcards
What is disease?
- a disorder of structure or function leading to signs and symptoms
- a deviation from a normal state of health
What causes disease?
- Genetic
- Environmental
- Microbial
Epithelial surfaces
interacting with the external environment
Bifidobacteria
-in breastfed babies
-synthesize all amino acids
have surface proteins that can bind sugars
Anatomic sites: skin
-staphylococcus!
Anatomic sites: GI tract/ oral cavity
-Streptococcus
Anatomic sites: Large intestine
- Bacteroides
- Bifidobacterium
Anatomical site: Genital tract
- Lactobacillus
- Excherichia
Anatomical site: Urinary tract
-Lactobacillus
Factors that alter your normal microbiota
- food
- antibiotics
- environment
- interactions
- age
- immune status
Resident microbiota
normally found in/on our body
transient microbiota
temporary organism
pathogen
an organism capable of causing disease
- true pathogen
- opportunistic
Virulence
severity of disease associated with a particular pathogen
Virulence factor
component of an organism that supports or enhances its ability to cause disease
Basic progression of microbes
- finding a portal of entry
- attaching firmly
- surviving host defenses
- causes of damage and disease
mechanical vs. biological vectors
mechanical- pathogen outside
biological- pathogen inside
Parenteral
bypassing barriers (cuts/needles/fluid-feeding insects)
Placental
crossing the placental barrier STORCH: -syphillis -toxoplasmosis -others -rubella -cytomegalovirus -herpes
endotoxins
LPS specifically the lipid A portion
Exotoxins
any secreted toxin. diverse
A/B toxins
A-Action
B-Binds
Factors that influence host susceptibility
genetics, gender, age, pregnancy, immune suppression, health/nutrition, other diseases
stages of disease: Incubation period
stage 1
time from initial contact with the infectious agent to the appearance of the first symptoms, agent is multiplying but damage is insufficient to cause symptoms, several hours to several days
stages of diseases: Prodromal stage
stage 2
vague feelings of discomfort, nonspecific complaints
stages of disease: period of illness
stage 3
disease is most severe, signs and symptoms
stages of disease; convalescent period
stage 4
as person begins to respond to the infection, symptoms decline
sign
objective evidence of disease as noted by an observer
symptom
subjective evidence of disease as sensed by the patient
epidemiology
science that evaluates occurrence, determinants, distribution and control of the health and disease in a defines human population
what causes disease and how it is spread
what does epidemiology determine?
- causative agent
- source or reservoir of disease agent
- mechanism of transmission
sporadic disease
Occurs occasionally and at irregular intervals.
endemic disease
Maintains a relatively steady low-level
frequency at a moderately regular
interval.
Hyperendemic diseases
Gradually increase in frequency above endemic level but not to epidemic level.
outbreak
- Sudden, unexpected occurrence of disease.
- Usually focal or in a limited segment of population.
epidemic
- Outbreak affecting may people at once.
- Sudden increase in occurrence above expected number.
- Index case—first case in an epidemic.
pandemic
Increase in disease occurrence within a large population over at least two countries around the world.
Morbidity
An incidence rate.
Number of new cases in a specific time period per unit of population.
Mortality
Number of deaths from a disease per number of cases of the disease.
incidence
measures the number of new cases over a certain time period, as compared with the general healthy population
prevalence
total number of existing cases with respect to the entire population usually represented by a percentage of the population
infectious disease
Disease resulting from an infection by microbial agents.
communicable disease
Can be transmitted from one host to another.
common source epidemic
single common contaminated source (food).
propagated apidemic
one infected individual into a susceptible group, infection propagated to others.
herd immunity
resistance of a population to infection and pathogen spread because of immunity of large percentage of the population.
why is herd immunity hard to achieve?
antigenic shift and drift.
diseases and microbes alter over time and can change (like the flu, different every year)
prevention and control of epidemics
- Reduce or eliminate source or reservoir of infection.
- Break connection between source and susceptible individual.
- Reduce number of susceptible individuals.
reduce number of susceptible individuals causes?
- Raises herd immunity.
- Passive immunity following exposure.
- Active immunity for protection.
systematic epidemiology
Focuses on ecological and social factors that influence development and spread of emerging and reemerging diseases.
reasons that diseases are appearing or reemmerging
- World population growth, urbanization.
- Inadequate public infrastructures.
- Increased international travel, mass migrations.
- Climate change.
- Habitat disruption.
- Microbial evolution and development of resistance.
endogenous pathogen
- Brought into hospital by patient.
- Patient is colonized after admission.
exogenous pathogens
Microbiota other than the patient’
nosocomial infections
- acquired in the hospital
- 5%-10% of patients get sick
Gram-positive cell walls
- cel wall
- no 2nd outer membrane
gram-positive bacterial pathogens
- Stain purple when Gram stained
- Two major groups based on DNA Low and high G/C
staphylococcus
“the perfect pathogen”
- Normal members of every human’s microbiota
- Can be opportunistic pathogens
- Common inhabitant of the skin and mucous membranes
- Lack spores and flagella
- May have capsules
staphylococcus structure and physiology
- Facultative anaerobes
- Salt-tolerant
- Tolerate salt on human skin
epidemiology of S. aureus
- Carriage rate for healthy adults is 20-60%
- MRSA carriage varies (1-5%), but is higher in HCWs
- Increase in community acquired methicillin resistance - MRSA
pathogenicity of S.aureus
- Infections result when staphylococci breach body’s physical barriers
- Entry of only a few hundred bacteria can result in disease
types of staphylococcal disease
- Cutaneous diseases
- Toxigenic/Noninvasive disease
- Systemic
localized cutaneous infections
invade skin through wounds, follicles, or glands
folliculitis
superficial inflammation of hair follicle, usually resolved with no complications but can progress
furuncle
boil; inflammation of hair follicle or sebaceous gland progresses into abscess or pustule
carbuncle
larger and deeper lesion created by aggregation and interconnection of a cluster of furuncles
impetigo
bubble-like swellings that can break and peel away; most common in newborns
food intoxication
ingestion of heat stable enterotoxins; gastrointestinal distress.
staphylococcal scalded skin syndrome
toxin induces bright red flush, blisters, then desquamation of the epidermis
toxic shock syndrome
toxemia leading to shock and organ failure
osteomyelitis
infection is established in the metaphysis; abscess forms
bacteremia
primary origin is bacteria from another infected site or medical devices; endocarditis possible
endocarditis
very aggressive. “acute endocarditis”. Often fatal. in heart
pneumonia
common cause of post influenza bacterial pneumonia
treatment of S.aureus
- cant be treated with penicillin
- Resistant forms can generally be treated with cephalexin!, sulfa drugs, tetracyclines, or clindamycin
- can have a lenghty recovery if not treated properly
treatment of MRSA
there are still a few drugs that will generally work, including vancomycin!, ceftaroline, linezolid, and daptomycin. Administration of two of these in combination is use to reduce further drug resistance
prevention of staph infections
- Universal precautions by healthcare providers to prevent nosocomial infections
- Hygiene and cleansing
- A vaccine aimed at providing protection against S. aureus is currently in clinical trials
characteristics of genera streptococcus and enterococcus
- Gram-positive spherical/ovoid cocci arranged in long chains; commonly in pairs
- Non-spore-forming, nonmotile
- Can form capsules and slime layers
- Facultative anaerobes
lancefield groups
based on cell wall Ag-17 groups. another classifications system is based on
what are the types of hemolysis?
β-hemolytic – complete hemolysis (clear)
α-hemolytic – partial hemolysis (can partially see)
what bacteria comes from beta-hemolytic?
- pyogenes
- agalactiae
what bacteria comes from alpha-hemolytic?
- viridins
- pneumoniae
beta-hemolytic strep
- Most serious streptococcal pathogen
- Strict parasite
- Inhabits throat, nasopharynx, occasionally skin
C-carbohydrates
protect against lysozyme
fimbriae
adherence
M-protein
contributes to resistance to phagoccytosis
hyaluronic acid capsule
provokes no immune response
C5a protease
hinders complement and neutrophil response
what diseases can be controlled?
environmental and microbial
what is the basic information for cystic fibrosis?
it causes the lungs to be sticky and it is a mutated gene
where should microbes not be?
in your lungs and bladder
what is a true pathogen?
it is a pathogen that always causes diseases or sickness when it comes in contact with your body
how does opportunistic pathogen cause diseases?
it waits to find an opportunity into your body as it needs a specific way to infect
infectious dose v. lethal dose
infectious: how many pathogens will infect 50% of populations
lethal: how many pathogens it takes to kill 50% of population
what is the main function of the CDC?
developing and applying disease prevention and control
what is the number 1 cause of death in America?
Heart disease
streptolysins
hemolysins; streptolysin O and streptolysin S – both cause cell and tissue injury
Erythrogenic toxin
induces fever and typical red rash
superantigens
strong monocyte and lymphocyte stimulants; cause the release of tissue necrotic factor
what are the 4 different strep diseases/
- cutaneous diseases
- throat infections
- systemic
- immune sequelae
Impetigo
superficial lesions that break and form highly contagious crust; often in epidemics in school children; also associated with insect bites, poor hygiene, and crowded living conditions
necrotizing fasciitis
the microbes get into the skin and starts to destroy the tissue
what can strep. be treated with?
penicillin
who gets group B: strep. agalactiae? and how is it transmitted?
- babies and young kids
- can be through delivery
what are the 6 viridans groups
- S. Mutans
- S. oralis
- S. salivarus
- S. sanguis
- S. milleri
- S. mitis
subacute endocarditis
blood-borne bacteria settle and grow on heart lining or valves
Strep. pneumoniae
- causes 60%-70% of all pneumonias
- cant live in oxygen
- large capsules
- causes pneumonia and otitis media
what does S. pneumoniae secrete?
IgA protease
how many people carry pneumococcus?
around 50% of population but its not activated
how is pneumonia activated?
- cells must be aspirated into the lungs
- when in lungs its multiplies fast and is hard to kill off
how do you treat pneumonia?
- pennicillin
- there are 2 vaccines avaliable
where is enterococcus faecalis found?
- GI tract of animals
- large intestines of humans
- must ravel in pairs
- opportunistic
- caused by surgery
endospore
dense survival unit that develops in a vegetative cell in response to nutrient deprivation. resistant to everything
characteristics of Genus Bacillus
- gram positive
- endospore-forming
- aerobic
- resistant to everything
- forms in soil
Bacillus anthracis
- the least dangerous
- spores that develop under all conditions but not in the human
Cutaneous anthrax
- spores enter through skin
- least dangerous
Pulmonary Anthrax
-inhaling spores from animal products or soil
Gastronintestinal anthrax
- ingested spores
- rare
Treatment of anthrax
- antibiotics
- control livestock
- vaccines
Genus Clostridium
- gram positive
- spore forming rods
- anaerobic
- endotoxins are produced
treatment and prevention of clostridial infections
- Prevent- vaccine and degerm
- Remove- amputation
- Kill- antibiotics
- Neutralize toxin- antitoxin
clostridium perfringens
- most frequent
- spores found in soil
- can occur from wounds, gunshot, surgery
cellutitis
infects the muscle tissue and kills it
myonecrosis
more destructive, grows and releases
what is clostridium perf. also involved in
food poisoning
Clostridium difficile
- c-diff
- in the intestine and causes diarhea
how can c-diff be treated?
antibiotics
Botulism
food poisoning from food being left out or contaminated
what does botulinum food poisoning do?
it blocks the release of transmission that tells your muscles to move
you cant inhale so you die
infant botulism
ingested spores
most common type
wound botulism
when spores enter the wound and cause food poisoning symptoms
Tetanus
- known as lockjaw
- causes muscles to NOT relax
- caused by botulism
Listeria monocytogenes
- non spore forming
- grown in cytoplasm of cell to hide and avoid the immune system
- grown in soil and animals
- resistant to cold
listeriosis
-dairy products and meat
-young and old are easily attracted to
pregnant women get 9why they cant eat things)
what are the characteristics of corynebacterium diphtheriae?
- curved rods
- diiphtheria is always present
- non immunzed children from droplets
what are the two stages of diphtheria?
- local: on skin and respiratory tract
- systemic: toxin produced resulting in death
prevention for diphtheria
-vaccine
what is propionibacterium
acnes
mycobacteria
- acid fast
- aerobic
- grows slowly
mycobacterium tuberculosis
- has a unique cell wall that prevents destruction using macrophages
- a big global problem
- low infectious dose
latent and recurrent TB
- lots of coughing and sputum
- the body slowly eats itsself and dies
detecting TB
- Mantoux test
- in vitro TB test
- chest x-ray
- acid fast staining
management of TB
can take 6-24 months
