Exam 1 - Introduction to infectious diseases Flashcards
This is part 1 & 2 of Dr. Rybakov's intro lectures. A separate slide deck is made of the gram +/- bacteria chart
commensal
microorganism that is a normal inhabitant of the human body
either microbe or host derives benefit
neither is harmed
pathogen
microorganism capable of causes disease
includes commensals and non commensals
commensal pathogen
microorganism that is commonly found within the indigenous microbiota and can cause disease in normal hosts
obligate pathogen
microorganism that must product diseases to transmit and thereby survive evolutionarily
zoonotic pathogen
microorganism that is a colonizer or pathogen in animals and that can be transmitted to humans
environmental pathogen
microorganism capable of causing disease that is transmitted to humans from an environmental source such as soil or water
what is considered a fever
> 38 C (100.4 F)
what are non infectious causes of a fever
drug induced fevers
malignancies
blood transfusions
auto-immune disorders
what can cause false negative fevers (infection but no fever present)
antipyretics
corticosteroids
overwhelming infection (patient goes hypothermic)
what are 5 systemic signs of an infection
hypotension
tachycardia (>90bpm)
tachypnea (>20rpm)
fever
increased or decreased WBC (>12,000 or <4000)
what are 4 systemic symptoms of infection
chills
rigor
malaise
mental status change
explain SIRS
systemic inflammatory response syndrome
screening tool for sepsis, pt needs to meet at least 2 criteria
what are the 4 criteria of SIRS
tachycardia
tachypnea
fever
increased or decreased WBC
what is leukocytosis
increased neutrophils +/- bands
what is leukocytosis associated with
bacterial infections
what is lymphocytosis associated with
viral, fungal, TB infections
explain ESR and CRP
ESR is the erythrocyte sedimentation rate
elevated in presence of inflammatory process and does NOT confirm infection
what is ESR and CRP used for
useful for determining response to treatment especially if its a long term infection
explain Procalcitonin (PCT)
specific marker for bacterial infection
will increase then decrease
magnitude will help provide diagnostic info
when should cultures be taken
before initiation of anti-infective therapy
what is a colonization
pathogenic organism present at the body site but is not invading host tissue or eliciting a host immune response
what is an infection
pathogenic organism is present at the body site and is damaging host tissue and eliciting a response and symptoms
how long does identification and susceptibility testing take
48-72+hrs
what is MIC
Minimum inhibitory concentration: lowest antimicrobial concentration that prevents visible growth
what is the breakpoint
MIC or zone diameter value used to categorize an organism as susceptible, susceptible-dose dependent, intermediate, resistant, or non-susceptible
what is susceptible in terms of testing
isolates with an MIC at or below zero diameter or below the S breakpoint are inhibited by the usual achievable concentrations of an agent when normal dosing is used
what is susceptible- dose dependent (S-DD)
implies susceptibility is dependent on dosing regimen (need higher doses)
what is intermediate
isolates with MICs approach achievable blood or tissue concentrations and response rates may be lower than for susceptible isolates
what is resistant
isolates not inhibited by usual concentrations of agent. efficacy not demonstrated
what is the gold standard for MIC testing
broth dilution
what is the disk diffusion assay and how does it work?
way to test susceptibility
up to abx disks placed on agar, drug is diffuses in concentration gradient out into the agar then compare zone diameters
can you get MIC from zone of inhibition
NO
what are gradient strip tests and how do they work?
-plastic strips with abx and placed on agar
-more precise for susceptibility testing
what are 3 automated systems for MIC testing
Vitek-2 system
MicroScan WalkAway
BD Phoenix Automated Microbiology System
empiric vs targeted therapy
-empiric is starting therapy before results are known. drugs chosen should cover most pathogens
-targeted therapy is when therapy is picked after organism is identified
what factors should be considered in abx selection
antibiogram
patient history
allergy & reaction
age/weight
pregnancy
gene/metabolic variations
organ dysfunction
other drugs
other disease states
drug factors
what factors should be considered when monitoring therapeutic drug response
culture and sensitivity reports
WBC, temp, physical complaints
IV to PO
antimicrobial failure
what is antimicrobial resistance
germs develop the ability to defeat the drugs designed to kill them
what are the core elements of antimicrobial stewardship
leadership commitment
accountability
pharmacy expertise
action
tracking
reporting
education
