Exam 1 Lecture 1 Flashcards
What is the hallmark of an infection?
Fever
(>38 celcius or 100.4 faranheit)
What are non infectious causes of fever? How are they caused?
Drug induced fevers
BEta lactams, antibiotics, sulfonamides, anticonvulsants
Non- drug causes- Malignancies, blood transfusion, Auto immune disorders
How do we get a false negative (absence of fever) in patients who have an infection?
Antipyretics (acetaminophen, NSAIDs, Aspirin)
What are some systemic signs we look at to establish the presence of infection?
Vital signs (Hypotension<90, tachycardia>90, tachypnea>20 RPM, fever >36)
Increased/decreased WBC count (>12,000 or <4000 or 10% immature forms)
What are the 4 criteria for systemic inflammatory response syndrome (SIRS)
HR, Respiratory rate, fever, Increased/decreased WBC
We need atleast 2 of these to meet SIRS criteria
What are systemic symptoms of infection
chills
Rigors
Malaise
Mental status changes
What are some local signs and symptoms of pyelonephritis, pneumonia and arthiritis, neutropenic symptoms
Pyelonephritis- flank pain
Arthiritis- swelling, erythema, tenderness, purulent or abnormal drainage
Pneumonia- inflammation
Neutropenia- fever only
What are the names of the WBCs in WBC count
Neutrophils, Lymphocytes, monocytes, eosinophils and basophils
What non infectious causes of elevation in WBC count
non infectious- steroids, leukemia
what is leukocytosis? What is it associated with?
Increased neutrophils +/- bands–>associated with bacterial infections
What does the presence of bands indicate in leukocytosis
presence of bands indicate increased bone marrow response to infection
What is lymphocytosis? What is it associated with?
Increase in B cells and T cells. Associated with viral, fungal or tuberculosis infections
What is ANC? WHat is the formula?
ANC is the total number of circulating segs and bands
ANC- WBC x [[% segs + % bands/100]]
What is Neutropenia? Levels that inducate neutropenia? profound neutropenia?
ANC<500 is neutropenia
ANC <100 is profound neutropenia
Correlation between ANC and risk of infection? When should we start to worry?
ANC< 500 is associated with substntial risk of infection? Start to worry when ANC < 1000
What meds could cause neutropenia?
Antibiotics (especially the lactam class)
WHat are acute phase reactants we can use to see if patient is infected
ESR and CRP
both non specific markers of infection and inflammation that can be elevated in presence of an inflammatory process.
Does NOT confirm infection
Procalcitonin is another acute phase reactant
Difference of procalcitonin and ESR/CRP
more specific for bacterial infection than ESR/CRP and its utility is going to be in sepsis as well as LRTI (lower respiratory tract infections)
Serial Measurements every 1-2 days useful in assessing response to therapy and when to dx antibiotics
Normal temp, HR, RR, O2 sat, WBC, X-RAY
Normal temp <100.4
HR<90
RR<20
O2 sat- 95-100
WBC<12,000
X-ray- No consolidation present if no infection
WHy should infected body materials be sampled before initiation of anti infective theraoy?
Because Gram-stain might reveal causative pathogen
Premature use of anti infectives can suppress growth of pathogens. Leads to false negatives or alterations of infected fluids
When should bone, CSF, blood culture and heart valve tissue biopsies be performed?
Bone biopsy- Osteomyelitis
CSF- Meningitis
Blood cultures, Heart valve tissues- Endocarditis
Blood cultures should be performed in acutely ill febrile patients, obtained from two different peripheral sites. (1 set of aerobic and anaerobic bottle from left and right arm 1 hour apart)
Difference between a colonization and an infection
Colonization- A potentially pathogenic organism present at the body site but is not invading host tissue or eliciting a host immune response.
Infection- A pathogenic organism is present at the body site and is damaging host tissue and eliciting host responses and symptoms consistent with infection.
TImeline of cultures process
Minutes to hours- Retrieve cultures from body and send to micro lab
24-48 hrs- Plate the organism, await growth, Gram- stain growing organsims
48-72 hrs- Identification and susceptibility testing
WHat is the difference between Phenotest BC kit and all of the other rapid diagnostic technologies
PhenoTest gives you susceptibility profile While the other ones only give genetic Identification. The others use Rapid PCR and Pheno uses FISH technology.
What are some other rapid diagnostic tests? Describe them?
MRSA PCR nasal test- Nasal swab used to identify presence/abscence of MRSA in the nares. Negative predictive value rules out MRSA respiratory infections there is 95% chance of no MRSA.
Biofire FirmArray Panels- also detects organisms in different body sources, not just blood.
What is the main term to be familiar with regarding susceptibility testing
MIC- lowest antimicrobial concentration that prevents visible growth
What is breakpoint? Susceptibility? Susceptible-dose dependent (S-DD)? Intermediate (II)? Resistant (R)? Non- susceptible (NS)?
Breakpoint- MIC or zone diameter that categorizes that categorizes an organism as susceptible, susceptible dose dependent, intermediate resistant, resistant or non-susceptible.
Susceptible (S)- Usual concentration of anti microbial agent can result in clinical efficacy
Susceptible dose dependent (S-DD)- Implies susceptibility is dependent on dosing regimen used.
Intermediate (I)- Isolates with MIC approach achievable blood or tissue concentration and response rates may be lower than for susceptible isolates.
Resistant (R)- Isolates not inhibited by usually achievable concentrations of agent. Clinical efficacy has not been reliably demonstrated
non-susceptible (NS)- If MIC is above or zone diameter is below the susceptible breakpoint, isolate is categorized as NS
What is the gold standard for MIC testing
Broth dilution
What is disk diffusion assay? What can and cant it do?
Disk diffusion reduces labor for tube dilution testing. Up to 12 antibiotic impregnated disks placed in an agar. CANNOT derive a MIC from zone of inhibition
Why do we use automated systems instead of kirby bouer systems or microdulution
They are all labor and time intensive. Automated testing systems are used.
What is Empiric therapy?
The first anti biotic therapy that we pick to target the most common pathogens. Usually very broad coverage. May require 2-3 anti infectives.
What is directed/targeted therapy?
Therapy selected after organism identification and/or susceptibility is known.
Define de escalation
Process of going from empiric therapy to directed therapy. To select agent with narrowest spectrum of activity
What is an antibiogram and what does it represent?
Annual summary of institution specific anti infective susceptibility. COntains number of nonduplicate isolates from common species and % susceptible to anti infectives tested.
Factors to consider in antibiotic selection
Patient hx- site of infetion, Recent travel, Prior culture history, previous antimicrobial exposure
Allergy
Age/weight
Pregnancy- alters PK, impacts on fetus
Metabolic/genetic variation
How to monitor therapeutic responses to antibiotics
Culture/sensitivity reports
WBC, TEMP, physical complaints should diminsih
Therapeutic drug monitoring
IV to PO switch if possible
factors to consider before switching antibiotics
Indication (signs/symptoms, imaging)
Source (pathophysiology)
Causative pathogen (empiric/ definitive)
Spectrum of activity
Resistance patterns
PK/PD
Monitoring parameters
Duration of therapy
What is a mnemonic to help memorize factors to consider when giving antibiotics?
Infection (indication)
Scare (source)
People (pathogens)
So (spectrum activity)
Really (resistance patterns)
Practice (PK/PD parameters)
Memorizing (monitoring parameters)
Drugs (duration of therapy)
what is antimicrobial resistence
Occurs when germs (Bacteria, fungi, viruses or parasites) develop the ability to defeat the drugs designed to kill them
Define Antimicobial stewardship (AMS)
Coordinated interventions designed to improve and measure the appropriate use of antibiotic agents by promoting the selection of optimal drug regimen including dosing, duration of therapy and ROA
Goal of AMS
Primary- optimize clinical outcomes, minimize unintended consequences
secondary goal- reduce healthcare cost without adversely impacting quality of care
