BACTE (IMMUNITY) Flashcards
COLONIZATION
presence and multiplication of new microorganisms that may cause an infectious disease or eliminated by host defenses
INFECTION
entrance and multiplication of a microorganism in or on a host
INFECTIOUS DISEASE
an infection w/ functional and structural harm to the host that is usually accompanied by signs and symptoms
PATHOgen
a microbe capable of causing a disease
PATHOlogy
study of the structural and functional manifestations of a disease
PATHOlogist
a physician specializing in pathology
PATHOgenicity
the ability to cause a disease by overcoming host’s defenses
PATHOgenesis
disease process
Virulence
degree of pathogenicity
Etiology
study of the cause/s of disease
Reservoir
environment or place of origin of the infecting agent
Measured by the number of organisms required to cause disease
VIRULENCE
Quantitative measure of pathogenicity
VIRULENCE
number of organisms needed to cause infection in half the hosts/population.
50% of infectious dose (ID50)
number of organisms needed to kill half of the hosts/population.
50% of lethal dose (LD50)
INFECTIONS (4 types)
NOSOCOMIAL INFECTION
COMMUNITY-ACQUIRED INFECTION
ENDOGENOUS INFECTION
EXOGENOUS INFECTION
Acquired in the HOSPITAL or other health care settings
NOSOCOMIAL INFECTION
Results from organisms from external sources
EXOGENOUS INFECTION
Causative agent is present or incubating at the time of admission into the health care facility
COMMUNITY-ACQUIRED INFECTION
Results from organisms that are part of the patient’s normal flora
ENDOGENOUS INFECTION
Bacteria most often associated w/ nosocomial infections include:
Staphylococcus aureus
Escherichia coli
Enterococcus faecalis
Pseudomonas aeruginosa
Most of these nosocomial pathogens are resistant to?
multiple antibiotics
Bacillus anthracis is?
TRUE PATHOGEN
Candida albicans is?
OPPORTUNISTIC PATHOGEN
microorganisms (bacteria, parasites, viruses, fungi, PRIONS) capable of causing an infectious disease
PATHOGENS
has the ability to infect a host w/ a healthy immune system as well as those in immunosuppressed state
TRUE PATHOGEN
attacks a debilitated host but presents no danger to a healthy individual
OPPORTUNISTIC PATHOGEN
Infections of the immunocompromised hosts that do not cause a disease in individuals w/ a normal immune system
OPPORTUNISTIC INFECTIONS
Opportunistic infections are increasing due to:
Widespread use of broad-spectrum antibiotics that can alter normal flora
Increased use of immunosuppressive drugs (in organ transplantation)
Chemotherapeutic agents (cancer)
Increased and prolonged use of urethral catheters
In immunosuppressive conditions, the host’s immune system is unable to effectively battle those microorganisms considered to be normal flora for the general population.
OPPORTUNISTIC INFECTIONS
Individuals at risk for opportunistic pathogens include:
Dialysis patients, Individuals on heart pumps
Diabetics, burn victims
Those w/ chronic medical problems; those undergoing invasive medical procedures
Those w/ foreign body implants (heart valves, prosthetic devices, IV catheters)
Alcoholics and IV drug users
Microorganisms normally residing in a particular body site; they do not usually cause an infection; also known as
usual or indigenous flora
2 types of normal flora
Transient flora
Resident microbial flora
Resident microbial flora
colonize an anatomical area for months or years
Transient flora
temporarily present at an anatomical site
Distribution of normal flora
Skin, Mouth and oral cavity, nasopharynx
Stomach and upper small intestine, colon
Urethra
STERILE
no normal flora
There are anatomical sites considered to be STERILE
BLOOD,
CEREBROSPINAL FLUID and
URINARY BLADDER
Normal flora can become pathogenic if they are
moved to another site
The slightly acidic pH (5.5-6.0) results from the presence of acids produced by its normal flora:
skin
Common NF of skin
Staphylococcus spp.
Propionibacterium acnes
Micrococcus
Candida
Clostridium
Diphtheroids
Less Common NF of skin
Streptococcus
Enterococcus
Acinetobacter
Bacteroides
Moraxella
Gram negative rods
MOUTH & ORAL CAVITY normal flora
Viridans streptococcus
Staphylococcus epidermidis
Neisseria (non-pathogenic spp.)
Moraxella catarrhalis
Lactobacilli
Diphtheroids
Anaerobic NF include:
Actinomyces
Veilonella
Bacteroides
May serve as a site of asymptomatic carriage of several microorganisms
NASOPHARYNX
Common NF of nasopharynx
Staphylococcus aureus
Staphylococcus epidermidis
Diphtheroids
Haemophilus parainfluenzae
Streptococcus
Less Common Nf of nasopharynx
Streptococcus pneumoniae
Moraxella catarrhalis
Haemophilus influenzae
Neisseria meningitidis
Other Moraxella spp.
maintain a reservoir for the organism but do NOT have an infectious disease BUT serve as an infectious source for others
Asymptomatic carriers
Asymptomatic carriers have?
Staphylococcus aureus
Neisseria meningitidis
Are usually sterile containing less than 1000 organisms/ml
STOMACH & UPPER SMALL INTESTINE
Organisms entering the stomach are usually killed by?
HCl and gastric enzymes
When organisms are passed in the small intestine, they may be destroyed by?
bile and pancreatic enzymes
When the gastric pH increases to over 5.0, colonization from bacteria of oral, nasopharyngeal, or colon may occur
Lactobacilli
Bifidobacteria
Heavily colonized and serves as a reservoir for infection for numerous body sites, including the urinary tract and peritoneal cavity
colon
normal flora of colon
Bacteroides
Lactobacillus
Clostridium
Eubacterium
Coliforms such as Escherichia coli
Aerobic and anaerobic streptococci
Yeast
Normal flora of the distal urethra in both males and females may contain:
Diphtheroids
Streptococci (alpha and non-hemolytic)
Peptococcus
Staphylococcus epidermidis
Bacteroides
Nf of GUT:
Lactobacillus spp.
Bacteroides spp.
Clostridium spp.
Peptostreptococcus
S. aureus
S. epidermidis
Environment or the place of origin of an infecting agent is referred to as the?
RESERVOIR
RESERVOIR can be?
Humans, Animals
Water, food, air, soil
Humans acquire microbial agents by various means referred to as
MODES OF TRANSMISSION
MODES OF TRANSMISSION can be:
direct or indirect
DIRECT
when the host directly contacts the microbial reservoir
INDIRECT
when the host encounters the microorganism by an intervening agent
The intervening agent can be a:
Vector – living entity
Vehicle/Fomite – non-living entity
DIRECT TRANSMISSION
Congenital contact
Sexual contact
Hand-to-hand contact
Droplet infection
May occur across the placenta or during passage at the birth canal
CONGENITAL/ VERTICAL TRANSMISSION
may be acquired during pregnancy
Rubella virus and Treponema pallidum
are examples of bacteria that may be transmitted to the infant during delivery
Streptocccus agalactiae and Neisseria gonorrhoeae
Serves as a route for many respiratory viruses and bacterial pathogens including:
Streptococcus pyogenes
Neisseria meningitidis
Infectious secretions may come from coughing, sneezing, kissing and nasal drainage
DROPLET INFECTION
Respiratory secretions can become dried on clothing, bedding, or floors and converted to dust, which may serve as a route of indirect transmission
DROPLET INFECTION
Route of infection for many sexually transmitted infections (STIs)
SEXUAL CONTACT
SEXUAL CONTACT examples
Gonorrhea, Syphilis
Chlamydia, HIV Infection
Herpes, Hepatitis B infection
Mode of direct contact seen w/ the
spread of common cold due to rhinovirus
transmission of GI infections (poor hand-washing, fecally contaminated hands)
HAND-TO-HAND CONTACT
INDIRECT TRANSMISSION
Fomites
Ingestion of contaminated food and water
Airborne routes
Animal or arthropod vectors
Frequent routes of nosocomial infections
fomites
Inanimate objects such as eating utensils, medical instruments, clothing, money, doorknobs, etc
fomites
Result of improper or poor sanitary measures
CONTAMINATED FOOD & WATER
CONTAMINATED FOOD & WATER Associated microorganisms include:
Salmonella
Shigella
Escherichia coli
Hepatitis A virus
Infections may be incidentally transmitted to humans through infected animals or insect (arthropod vectors)
VECTORS
Inhalation of infectious particles (aerosols) suspended in air
AIRBORNE
SIGNS OF INFECTION
Acute infection
Chronic or subacute infection
Local signs of infection
Chronic or subacute infection
Intermittent, low-grade fever
Weight loss
Fatigue
Local signs of infection
Pain (dolor)
Heat (calor)
Redness (rubor)
Swelling (tumor)
Acute infection
High-grade, spiking fever
Chills
Vasodilation w/ flushing
Increased pulse rate
Differential wbc count
Bacterial infections
Viral infections
Bacterial infections
increased percentage of neutrophils
Viral infections
increased percentage of lymphocytes
OCCURRENCE OF A DISEASE
INCIDENCE
PREVALENCE
INCIDENCE
refers only to new cases
PREVALENCE
old and new cases of a disease
CLASSIFICATION OF DISEASES
COMMUNICABLE DISEASE
CONTAGIOUS DISEASE
NON-COMMUNICABLE DISEASE
COMMUNICABLE DISEASE
disease that spreads from one host to another either directly or indirectly
CONTAGIOUS DISEASE
disease thaqt easily spreads from one person to another.
SPECIFIC GROUP of signs or symptoms may always accompany a particular disease
SYNDROME
If disease is not spread from one host to another
NON-COMMUNICABLE DISEASE
Caused by microorganisms that normally inhabit the body and only occasionally produce disease.
NON-COMMUNICABLE DISEASE
Caused by microorganisms that reside outside the body and produce a disease only when introduced into the body.
NON-COMMUNICABLE DISEASE
HERD IMMUNITY
when many immune people are present in a community that they would act as barriers to the spread of infectious agents
