Module 1 - Infection Flashcards
Types of microbes
Bacteria
Viruses
Parasites
Fungi
Prokaryotes
no nucleus
unicellular or multicellular
Examples of Prokaryotes
Archaea
Bacteria
Eukaryotes
have a nucleus
cellular or multicellular
Types of Eukaryotes
Protist Fungi Plants Animals Helminths
Types of Fungi
eukaryotes
yeast (unicellular)
mold (multicellular)
Helminths
multicellular parasitic worms –> ANIMALS
eggs/larvae are disease producing
grow in threads
Hyphae
thread-like growth of helminths
Gram-negative bacteria
stain red on a Gram test
antibiotic resistant
produce endotoxins –> cause symptoms (fever, shock) when cell wall disturbed
Gram-positive bacteria
stain violet on a Gram test
treated with antibiotics
produce exotoxins
Which bacteria does not respond to penicillin
Gram-negative bacteria
Virulence Factors
secreted enzymes/toxins
mechanism of adhesion (viral spike proteins)
ability to evade immune defenses
ability to survive in environment or disinfection
Virulence
degree of pathology caused by a pathogen
exists on a continuum
quantitative
Carrier State
subclinical but infectious
Commensals
colonizing microbes naturally found on host
Protist
any living organism that is not a fungi, animal or plant
ex: algae, protozoa
Peptidoglycan
polymer found in most bacterial cell ways
neutralized by penicillin
Chitin
polysaccharide found in fungal cell walls
Virions
viral particle
C. diff characteristics
Gram-positive bacteria –> form exotoxins A/B
anaerobic
spore-forming
What route does C. diff travel?
fecal-oral
C. Diff symptoms
diarrhea fever abdominal cramping loss of appetite nausea dehydration
C. Diff Risk Factors
co-morbidities immunocompromised hospitalization or long-term care medication (antibiotic, chemotherapy) age (65+)
C. diff reservoir
feces, soil, GI tract
C. Diff Diagnosis
fecal culture
C. Diff Precautions
Contact plus precautions
gloves
gown
mask
goggles
wash hands with soap + water
Opportunistic Pathogen
a naturally occurring microbe (commensal) that becomes pathogenic when host is immunocompromised
Helminths
multicellular parasitic worms
Infection Definition
disease process that occurs when body is unable to defend against a pathogen
pathogens penetrate into deeper tissues causing a disease state OR
pathogen does not penetrate into deeper tissue but releases toxins causing a disease state
Stages of infection
1) Colonization
2) Infection
Colonization
pathogen takes residence on host and begin to multiply
do not penetrate into deeper tissues
subclinical
Types of Infection
Acute (few days to weeks)
Chronic (12+ weeks)
Spread of Infection
Localized
Disseminated
Systemic
Sepsis
Which WBC defends against bacterial infections
Neutrophils
Which WBC defends against parasitic infections
basophils
eosionophils
Which WBC defends against viral infections
lymphocytes (T+B Cells)
Common HAIs
C. Diff
VRE
MRSA
Prion
Infectious abnormal proteins causing disease
Main cause of CJD Dementia
Cellular pathogens
Bacteria
Fungi
Parasites
Acellular pathogens
Prions
Viruses
Virions (virus particles)
Types of noninfectious disease
Inherited Congenital Degenerative Nutritional deficiency Endocrine Neoplastic Idiopathic
Inherited disease
genetic (hereditary) disease
ex: sickle cell anemia
Congenital disease
disease present at birth
ex: down’s syndrome
Degenerative
disease that worsens/progresses over time
ex: parkinson’s
Nutritional deficiency
disease that occurs as a result of malnutrition
ex: scurvy
Endocrine
disease that occurs due to impairments/pathology in the hormonal glands
ex: hyper/hypothyroidism
Neoplastic
abnormal tissue growth (tumor) –> benign or malignant
ex: some forms of cancer
Idiopathic disease
disease without a discernible origin
ex: idiopathic juxtafoveal retinal telagniectasia
Stages of disease
Incubation Prodromal Illness Decline Convalescence
Types of disease
Acute
Chronic
Latent
Acute disease
rapid onset
infection lasts few hours to weeks
infection resolved
Chronic disease
slow onset
infection may last from weeks to years
may not be curable (i.e. chronic infections)
pathogen levels remain high over time
Latent disease
delayed onset
pathogen may remain in a dormant state for years before becoming activated
pathogen levels remain low and then spike
not transmissible when dormant
Primary Pathogen
causal pathogen directly responsible for illness/disease
always causes disease
Opportunistic Pathogen
pathogen that is normally present on/in the body (commensal) but becomes pathogenic under special circumstances
Opportunistic Pathogen Risk Factors
stress immunocompromised change in normal microflora due to medication pregnancy microbe moves to a new body region
Median Infectious Dose (ID50)
median amount of pathogenic particles needed to cause infection in 50% of vaccinated individuals
inverse relationship with virulence
Median Lethal Dose (LD50)
median amount of pathogenic particles needed to cause mortality in 50% of an infected population
inversely related with virulence
Primary Infection
infection caused directly by a pathogen
Secondary Infection
infection caused as a result of a primary infection or treatment of a primary infection
Endotoxin
lipopolysaccharides found in the cell walls of gram-negative bacteria
released upon disruption of bacterial cell wall
Exotoxin
secreted by gram-positive bacteria
Sequelae
abnormal condition resulting from previous disease
post-infection complications
Microbial antagonism
inhibition of one microbe by another
commensals inhibit microbial colonization of pathogens
Slow disease
acute infection is not fully cured
disease is minimized, but is not dormant. over time wears out the immune system resulting in secondary infection
Dysbiosis
microbial balance
ex: reduction in number of bacteria, reduction in diversity, overgrowth of certain bacteria
caused by various factors: antibiotics
Vector transmission
a living organism transmits a pathogen to another host
can be mechanical or biological vector
Vehicle transmission
a contaminated fluid, air or food transmits disease
Fomite transmission
Indirect contact
a contaminated object/surface
Commensal
a microbe that is part of the resident microflora.
can be become pathogenic under certain circumstances (opportunistic pathogen)
Stages of Infection
Exposure
Adhesion
Invasion
Infection
C. diff incubation period
5-10 days
C. diff epidemiology
2-5% adults colonized
10-20% older adults colonized
C. diff risk populations
frail older adults
peripartum women and children
antibiotic treatment
