AST and the Clinician
Transcript of AST and the Clinician
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AST and the Clinician
Piotr Chlebicki
Senior Consultant
Department of Infectious Diseases
SGH
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The assignment
Use of antibiotics in clinical practice:
- common infections- approach to diagnosis & treatment
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I modified it a bit
1. How do clinicians prescribe antibiotics ?
2. How does microbiology lab influenceprescribing?
3. A few clinical cases
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How do clinicians prescribe antibiotics?
A. Based on culture results
B. Empirically = 7 steps 1. Define the problem/disease/syndrome
2. Severe?
3. At risk of MDRO?
4. Immunocompromized?
5. List possible bugs and consider local
resistance patterns 6. Pick the best antibiotic
7. Decide duration
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How does microbiology lab
influence prescribing?
Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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Antibiograms
How many isolates? Duplicates? Outpatient?
When last updated? Impact on prescribing:
developing clinical pathways for empiric
antimicrobial treatment
monitoring resistance trends
updating the drug formulary
developing antimicrobial restriction policies
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Antibiogram
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Antibiogram single unit
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Selective antimicrobial
susceptibility reporting Susceptibilities are reported for only the most
appropriate and least expensive drugs towhich the organism is susceptible.
The use of a cascading microbiology report
encourages clinicians to select more narrow-spectrum and cost-effective antimicrobialagents.
Very effective!!
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Susceptibility pattern of urinaryE. coliAntibiotic Susceptibility
Ampicillin R
Co-amoxiclav S
Cephalexin S
Cefuroxime S
Cefotaxime S
Ceftazidime S
Cefepime S
Cefoxitin S
Pip-tazobactam S
Meropenem S
Ciprofloxacin S
Nitrofurantoin S
Co-trimoxazole S
Amikacin S
Gentamicin S
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Antimicrobial stewardship
there is an association between antibiotic susceptibility
reporting from microbiology laboratories and antibioticprescribing for the treatment of urinary tract infections.
Ciprofloxacin and risk of resistant organisms e.g.C. diffi
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Prospective interrupted time series
A. Before - susceptibility to amoxicillin,nitrof urantoin, trimethoprim and co-amoxiclav routinely
reported
B. After (9 months) - susceptibility to cefalexin wasreported in place of susceptibility to co-amoxiclav.
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Result
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Antimicrobial stewardship
Prioritization of tested antimicrobials and selective reportingof susceptibility profiles (e.g., not routinely reporting
susceptibility ofS. aureus to rifampin to prevent inadvertentmonotherapy with rifampin) can aid in the prudent use ofantimicrobials and direct appropriate therapy based on localguidelines
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How does microbiology lab
influence prescribing?
Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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MRSA MIC
2012 in SGH
Of the 112 tested isolates, 58 had MIC of 1.5or greater (51.8%)
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Case 1
52 year old man, PMH of DM, smoker
complains of fever and cough for 3 days. 120/70 HR 100, RR 25, 38.6C
Creps over rt lung
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How do clinicians prescribe antibiotics?
A. Based on culture results
B. Empirically = 7 steps 1. Define the problem/disease/syndrome
2. Severe?
3. At risk of MDRO? 4. Immunocompromized?
5. List possible bugs and consider local
resistance patterns 6. Pick the best antibiotic
7. Decide duration
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Diagnostic testing
Mild CAP = testing optional
More severe CAP = more testing
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How does microbiology lab
influence prescribing?
Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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Gram stain
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Quality of specimen Please reject
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Rapid diagnostic testing Urinary streptococcal antigen
Legionella urinary antigen Respiratory virus multiplex PCR
H d i bi l l b
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How does microbiology lab
influence prescribing? Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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Antibiotics Likely pathogens
Antimicrobial resistance
Can he be treated with azithromycin alone?
How about IV penicilln and Klacid?
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Spectrum IPD - Singapore experience
Journal of Medical Microbiology (2009), 58, 101104
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Methods All invasive pneumococcal isolates cultured
from sterile sites from adult patientshospitalized at SGH between 1 January 2000
and 31 December 2007
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Results Pneumococcal isolates from 192 patients
Blood cultures (92.7 %) Pleural fluid (2.1 %)
Intraophthalmic (1.6 %)
CSF (1.0 %) Synovium (1.0 %),
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Resistance in SGH The median penicillin MIC was 0.016 mg/ml
(range 0.0162 mg/ml)
Median ceftriaxone MIC 0.016 mg/ml (range
0.0041 mg/ml)
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Resistance in SGH All 186 non-meningitis isolates would be
classified as penicillin-susceptiblefollowing the new CLSI breakpoints
One isolate from a patient with meningitis had
an MIC to penicillin of 2 mg/ml, but the otherfive isolates were susceptible.
Ceftriaxone MIC >0.5 = 6/192 cases (3.13%)
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NARSS 2010
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Guideline
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Case 2 33 yo woman presents to Bedok polyclinic
with dysuria, urgency and frequency x 2 days. She has no fever or flank pain.
She had 2 similar episodes in the past 2
years
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How do clinicians prescribe antibiotics?
A. Based on culture results
B. Empirically = 7 steps 1. Define the problem/disease/syndrome
2. Severe?
3. At risk of MDRO? 4. Immunocompromized?
5. List possible bugs and consider local
resistance patterns
6. Pick the best antibiotic
7. Decide duration
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What is the bug?
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Which antibiotic? Depends on the prevalence of resistance in a
community IDSA suggests thresholds above which a
drug is not recommended
20% for trimethoprimsulfamethoxazole 10% for fluoroquinolones
How does microbiology lab
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How does microbiology lab
influence prescribing? Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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Old, good times (2002)
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New, not that good times (2009)
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Methods and patients Bedok Polyclinic
January 1 to December 31, 2009 1,352 patients coded as UTI
666 (49.3%) patients had urine cultures
333 (50%) culture-positive
34 , 299
1365 years = 214
> 65 years = 117
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Limitations No correlation with symptoms
No correlation with pyuria No attempt to differentiate true community
acquired vs healthcare associated
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Case 3 Hematology department in SGH introduced
febrile neutropenia protocol several yearsago. Cefepime was the drug of choice for
empiric therapy
Recent studies and resistance trends suggestthat it may not be the best choice
Is there any other antibiotic that is better?
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Cefepime versus other All-cause mortality was significantly higher
with cefepime as compared with otherantibiotics, RR 1.39 [1.04, 1.86], without
heterogeneity 21 trials, 3471 participants
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Piperacillin-tazobactam versus other
All-cause mortality was lower with
piperacillin-tazobactam versus all otherantibiotics , RR 0.56 [0.34, 0.92], 8 trials,
1314 participants
The difference was statistically significantalso in the comparison restricted to
carbapenems, RR 0.46 [0.22, 0.95].
How does microbiology lab
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influence prescribing? Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology
Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
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SGH data for hematology 2012
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CGH data, ESBL E coli, 2012
C 3
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Case 3
Febrile neutropenia protocol was changed
Pip tazo or cefepime plus amikacin will beused for the empiric therapy of febrileneutropenia
How does microbiology lab
i fl ibi ?
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influence prescribing?
Organism identification and pathogen
susceptibility patterns Selective reporting
MIC reporting
Local epidemiology Choice of available tests
Rapid diagnostic tests
Automatic alerts for targeted pathogens
S
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Summary
The impact of microbiology lab on prescribersis profound
It not only influence the choice of antibioticsfor individual patients but also hospital
policies and guidelines