ID 1 Rybakov Flashcards
Establishing Presence of Infection
___ : hallmark of infection
- > ___ C or ___ F
non-infectious causes (false positives)
- ___ induced fevers
- malignancies
- blood transfusions
- autoimmune disorders
no fever with s/s (false negatives)
- ___ ( ___ , ___ , and ___.)
- corticosteroids
- overwhelming infection may be hypothermic
fever
- 38, 100.4
- drug
- antipyretics (acetaminophen, NSAIDs, aspirin)
Establishing Presence of Infection
systemic signs
- BP (hypotension SBP < ___ mmHg)
- HR (tachycardia > ___ BPM)
- RR (tachypnea > ___ RPM)
- fever ( > ___ or < ___ C)
- increased/decreased WBC (> ___ or < ___ or > ___ % immature forms (bands))
systemic symptoms
- chills
- rigors
- malaise
- mental status changes
- 90
- 90
- 20
- 38, 36
- 12,000, 4,000, 10
Establishing Presence of Infection
4 criterias for systemic inflammatory response syndrome (SIRS)
at least 2 criteria needed
- HR
- RR
- fever
- WBC
Establishing Presence of Infection: Local Signs and Symptoms
___ and ___
- may be absent in ___ patients
pain, inflammation
- neutropenic
Establishing Presence of Infection: Lab Tests (WBC)
normal: ___ - ___ cells/mm3
- neutrophils, lymphocytes, monocytes, eosinophils, and basophils
- dependent on age, gender, and comorbidity status
elevated in response to infectious and non-infectious causes
- non-infectious: ___ , ___ , stress, rheumatoid arthritis, pregnancy
- 4,500-11,000
- steroids, leukemia
Establishing Presence of Infection: Lab Test (WBC)
mature neutrophils (PMNs, polys, ___ )
- most common WBC
- fight infections
immature neutrophils ( ___ )
- increase during infections = ___ shift
___ : involved in allergic reactions and immune response to parasites
___ : associated with hypersensitivity reactions
___ : __ cell (humoral) and __ cell (cell mediated) immunity
___ : mature into macrophages, serve as scavengers for foreign substances
- segs
- bands
- eosinophils
- basophils
- lymphhocytes, B, T
- monocytes
Establishing Presence of Infection: Lab Test (WBC)
Leukocytosis
- increased neutrophils w/wo ___ = assocaited with ___ infections
- bands present = increased ____ response ( ___ shift)
- may be elevated due to non-infectious disease ( ___ or ___ ) or drugs ( ___ )
- ___ (abnormally low WBC) may be a sign of overwhelming infection; poor prognosis
- bands, bacterial
- bone marrow, left
- leukemia, stress, steroids
- leukopenia
Establishing Presence of Infection: Lab Test (WBC)
Lymphocytosis
- associated with ___ , ___ , or ___ infections
- ___ cells and ___ cells
- fungal, viral, TB
- B, T
Establishing Presence of Infection: Lab Test (WBC)
Absolute Neutrophil Count (ANC)
- total number of circulating ___ and ___
Neutropenia
- ANC < ___ cells/mm3
- ANC expected to decrease to < ___ cells/mm3 in the next ___ hrs
- ANC < ___ cells/mm3 is termed profound neutropenia
Risk of infection dramatically ___ as ANC ___
- ANC < 500 = substantial risk of infection
- start to worry when ANC is < ___ cells/mm3
- segs, bands
- 500
- 500, 48
- 100
- increases, decreases
- 500
- 1000
Establishing Presence of Infection: Acute Phase Reactants (ESR and CRP)
erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
- elevated in the presence of an ___ process: does NOT confirm ___
Normal levels
- ESR: ___ - __ mm/hr (males); __ - ___ mm/hr (females)
- CRP: __ - __ mg/dL
Often elevated in presence of infection
- ___ measurements useful to determine response to treatment
- inflammatory, infection
- 0-15, 0-20
- 0-0.5
- serial
Establishing Presence of Infection: Acute Phase Reactants: Procalcitonin
Procalcitonin (PCT)
- precursor to ___ = more ___ for bacterial infections than ESR and CRP
- normal level: ___ mcg/L
- increase 3-12 hours after stimulation; decline over 24-72
Magnitude of elevation provides useful diagnostic information
- < ___ mcg/L = low risk of infection
- > ___ mcg/L = antibiotics should be continued
___ measurements every 1-2 days useful to assess response to therapy and when to d/c antibiotics
- calcitonin, specific
- 0.05
- 0.25
- 0.5
- serial
Establishing Presence of Infection: Radiographic Tests
- X-rays
- CT
- MRI
- Nuclear imaging
- echocardiography
Identification of the Pathogen: Microbiological Studies
infected body materials must be sampled, if possible or practical
Before initiation of anti-infective therapy
1) ___ might reveal causative pathogen
2) ___ use of anti-infectives can suppress growth of pathogens: leads to false negatives or alterations of infected fluid
Must avoids contaminations
- example: isolation of ___ negative staphylococcus from 1 of 2 blood cultures where blood was collected by peripheral stick
- gram stain
- premature
- coagulase
Identification of the Pathogen: Microbiological Studies
type of culture collected depends on ___ of infection
- Osteomyelitis: ___ biopsy
- Meningitis: ___
- Endocarditis: ___ cultures, heart valve tissues
Blood cultures
- shoud be performed in acutely ill ___ patients
- obtained from 2 different ___ sites as ___ sets: 1 set = 1 ___ and 1 ____ bottle (1 hr apart optimal)
- site
- bone
- CSF
- blood
- febrile
- peripheral, 2, aerobic, anerobic
Identification of the Pathogen: Microbiological Studies
Colonization:
- A potentially ___ organism is present at the body site but is not invading host tissue or eliciting a host immune ___
- no symptoms, there but not doing anything
Infection:
- A pathogenic organism is present at the body site and is ___ host tissue and eliciting host ___ and symptoms consistent with an infection
- symptoms
- pathogenic
- response
- damaging, response
Identification: Rapid Diagnostics for Bloodstream Infections
Which 2 tests cannot detect resistance genes?
A) PhenoTest BC Kit
B) BioFire BCID2
C) ePlex BCID
D) T2 Bacteria
E) Verigene
A) PhenoTest BC Kit
D) T2 Bacteria
Identification of the Pathogen: Other Rapid Diagnostic Tests
MRSA PCR Nasal Test
◦ Negative predictive value to rule out MRSA respiratory infections is ~ ___ %
Biofire FilmArray Panels
◦ Respiratory, blood culture, GI, meningitis/encephalitis, pneumonia, joint infections
◦ ___ test to detect a variety of pre-determined pathogens commonly associated with the infection
Verigene Panels
◦ Respiratory, blood culture, GI
◦ ___ test to detect variety of pre-determined pathogens commonly associated with the infection
- 96%
- PCR
- PCR
Definitions
Minimum Inhibitory Concentration (MIC)
lowest antimicrobial concentration that prevents visible growth
Definitions
Breakpoint
MIC or zone diameter value used to categorize an organism as S, S-DD, I, R, or NS
Definitions
Susceptible (S)
Isolates with an MIC or zone diameter at or below the (S) breakpoint are inhibited by the usually achievable concentrations of antimicrobial agent when normal dosing regimens are used, resulting in
likely clinical efficacy
Definitions
Susceptible-dose dependent
implies susceptibility is dependent on the dosing regimen used
Definition
Intermediate (I)
Resistant (R)
Non-susceptible (NS)
do not choose antibiotics with these markers
Identification of the Pathogen: MIC Testing (Broth Dilution)
Broth dilution
- gold standard
- MIC = concentration with lowest visible growth
- “ ___ “ = no ability to determine exact inhibitory concentration
what would the MIC of this picture be?
- semi-quantitative
- 2
Identification of the Pathogen: Susceptibility Testing (Disk Diffusion)
Disk Diffusion (Kirby-Bauer method)
- zone diameters measured and compared with standard zone size ranges
only results are ___ , ___ , or ___
- cannot derive a ___ from the zone of inhibition
- S, I, R
- MIC
Identification of the Pathogen:
Susceptibility (Gradient Strip Tests)
- also called ___ test
- plastic strip with known antibiotic concentration gradient placed on agar plate streaked with known bacteria
- MIC = concentration on strip where inhibition zone intersects the scale on the strip
- more ___ than standard methods
- Epsilometer, E-test
- precise
MIC Testing via Automated Systems
___ System
- Uses small reagent “cards” that test predetermined bug/drug combos
- Growth curves calculated for all wells compared to growth control curve
- Algorithm-derived MIC
___ WalkAway
- Uses fluorogenic substrate hydrolysis as an indicator of bacterial growth
- Uses standard microdilution trays
- Algorithm-derived MIC
__ ___ ___ ___ System
- Utilizes an oxidation-reduction detector and turbidometric growth detection system to determine susceptibility
- Uses microdilution trays
- Algorithm-derived MIC
- Vitek-2
- MicroScan WalkAway
- BD Phoenix Automated Microbiology
T or F: you can directly compare MIC values to determine the “best” option
FALSE
look at susceptibility to determine (and if broad coverage is needed)
Factors to Consider In Antibiotic Selection: Definitions
Empiric Therapy
- Initiation of anti-infective therapy ___ identification and susceptibility results are known
- Anti-infective selected should cover most common pathogens
- Usually very ___ coverage; may require 2-3 anti-infectives depending on site
Directed (targeted) Therapy
- Therapy selected ___ organism identification and/or susceptibility is known
De-escalation
- Selecting an anti-infective with the ___ spectrum of activity
- Can be stepwise or all at once
Spectrum of activity
- What ___ does the ___ cover
- before
- broad
- after
- narrowest
- bacteria, drug
Factors to Consider In Antibiotic Selection
pt has pneumonia
- ___ : cefepime
preliminary cultures growing E. coli
- ___ : ceftriaxone
pan-susceptible E. coli
- ___ (targeted): amoxicillin
- empiric
- de-escalation
- de-escalation
Factors to Consider in Antibiotic Selection: Antibiogram
Annual summary of ___ -specific anti-infective susceptibility
- Contain number of nonduplicate isolates from common species and ___ susceptible to anti-infectives tested
- Can be narrowed to ___ -specific (ex. ICU vs. ED vs. Med/Surg)
- Can be general or very detailed
- institution
- %
- unit
factors to consider in antibiotic selection
- patient Hx
- allergy
- age/weight
- pregnancy
- metabolic/genetic variation
- organ dysfunction
- concomitant drugs
- concomitant disease states
- drug factors (PK/PD, toxicity, cost, tissue penetration)
Monitoring Therapeutic Response
Culture and ___ reports
WBC, temperature, physical complaints (should ___ )
- ___ improvement lags behind clinical improvement
Therapeutic Drug Monitoring (TDM)
__ to __ switch (if possible)
Antimicrobial failure
- Drug selection
- Host Factors
- Microorganism
- sensitivity
- diminish
- IV, PO
Factors to Consider in Antibiotic Selection:
Putting It All Together
- ___ (s/s, imaging)
- ___ (patho)
- (Causative) ___ (empiric = probable, definitive = isolated)
- ___ of Activity (bug/drug mismatch)
- ___ Patterns (antibiogram considerations)
- ___ Parameters (host factors, dose, target site penetration, bioavailability, etc.)
- ___ Parameters (AE< allergies, DIs, TDM, etc.)
- ___ of Therapy
1) Indication
2) Source
3) Pathogens
4) Spectrum
5) Resistance
6) PK/PD
7) Monitoring
8) Duration
Factors to Consider in Antibiotic Selection:
Putting It All Together
“Infections Scare People So Really Practice Memorizing Drugs”
1) Indication
2) Source
3) Pathogens
4) Spectrum of activity
5) Resistance patterns
6) PK/PD parameters
7) Monitoring parameters
8) Duration of therapy
How Germs Fight Against Antibiotics
- develop new cell processes that avoid using the antibiotic’s target
- change or destroy the antibiotics with enzymes
- restrict access by changing the entryways (or limiting the number of entryways)
- change the antibiotic’s target so the drug can no longer fit and do its job
- get rid of antibiotics using pumps
Definition of Antimicrobial Stewardship (AMS)
“Coordinated interventions designed to improve and measure the appropriate use of antibiotic agents by promoting the selection of ___ drug regimen including ___ , ___ of therapy, and ___ of administration”
- optimal
- dosing, duration, route
Goals of AMS
Primary Goal:
- Optimize clinical outcomes while minimizing unintended consequences
Unintended consequences:
- Toxicity
- Selection of pathogenic organism such as ___
- Emergence of ___ pathogens
Secondary Goal:
- Reduce healthcare ___ without adversely impacting quality of care
- C. difficile
- resistant
- cost
Examples of AMS Strategies
Antibiotic de-escalation - switching to ___ -spectrum antibiotic that targets causative pathogen(s) identified on culture or those thought to be causing the infection
Prospective ___ and feedback - external review of antibiotic therapy with suggestions to optimize use after the agent has been prescribed
____ - Requiring approval from ID Pharmacy/ID Physician prior to use of certain antibiotics
Antibiotic ___ - Reassessment of the continuing need and choice of antibiotic, usually after 48-72 hours of therapy
Development of policies and protocols aimed at optimizing antimicrobial use
Creation of ___ aimed at optimal antibiotic selection for difference disease states
- narrower
- audit
- pre-authorization
- timeout
- order sets
B) Require ID pharmacist approval before ordering broad spectrum antibiotic
