PV DG an hean Yen
o nterpret in ter pret explain the meaning of (information, words, or actions)
o nterpret analyse susceptibility results based: organism identification all antibiotic results (pattern) interpret susceptibility based on above Courvalin P. nterpretive reading of in vitro antibiotic susceptibility tests (the antibiogramme). Clinical Microbiology and nfection. 1996;2:26 34.
Why interpret? o detect unusual results that need further testing or confirmation o report appropriate antibiotic results for the organism-infection combination o detect emerging resistance
xpert rule X P Description of action to be taken, based on current evidence, in response to specific antimicrobial susceptibility test results U L f you obey all of the rules, you miss all of the fun. - Katharine Hepburn
ctions X P U L ecommendations on reporting nference of susceptibility dit results from to or, from to, but V or to uppression of results ddition of comments dvice on further tests dvice on referral of isolates Brown, D. Concepts and needs for expert rules and intrepretive reading of the antibiogram. he UC perspective
equirements dentification of the organism (fully) X P U L May need to test an extended range of appropriate antibiotics ccess to a set of expert rules
hree areas to cover 1. ntrinsic resistance 2. antibiogramreading 3. xceptional phenotypes
Part One C C
C C Chromosomal (born with it) resistance which is a characteristic of the species usceptible results? errors in identification or susceptibility testing drug should be used with caution
xamples C C Organism nterobacteriaceae Gram-positive organism Klebsiella species Proteus mirabilis erratia marcescens ntibiotic resistance Vancomycin ztreonam mpicillin itrofurantoin Polymyxins Polymyxins
C C Livermore DM, et al. nterpretative reading: recognizing the unusual and inferring resistance mechanisms from resistance phenotypes. J ntimicrob Chemother. 2001 Jul 1;48(suppl 1):87 102
C C http://www.eucast.org/expert_rules/
Part wo BOGM DG
B O G M D G est susceptibility nfer resistance mechanism nterpret clinical susceptibility on the basis of the resistance mechanism Canton,. xpert ules n usceptibility esting ationale, dvantage nd Disadvantages. CCMD 31 March-3 pril, 2012
pecies identification ntibiotic susceptibility X P U L PO
pecies identification ntibiogram interpretation ntibiotic susceptibility X P U L clinical relevance additional tests 1. re-define susceptibility (categorical) 2. deduce susceptibility to non-tested antibiotics 3. clinical comments 4. clinical advice deduce phenotype deduce biochemical resistance PO
imple.. B O G M D G taphylococcus aureus esult: nfer: nterpret: resistant to cefoxitin resistance mediated by mec resistant to all beta-lactams
More complicated.. B O G M nterobacteriaceae esult: tobramycin non-susceptible amikacin & gentamicin susceptible D G nfer: nterpret: acquired C(6 )- enzyme report amikacin as ntermediate
scherichia coli B O G M D G ntibiotic mpicillin moxicillin-clavulanate Piperacillin-tazobactam Cephalothin Ceftriaxone Ceftazidime Cefepime Cefoxitin rtapenem Gentamicin mikacin Category nfer: xtended spectrum beta-lactamase (CX-M) nterpret: Consider reporting ceftazidimeas resistant O eporting presence of BL with comment Ciprofloxacin rimethoprim-sulfamethoxazole
Klebsiella pneumoniae B O G M D G nfer: ampc enzyme (plasmid-acquired) nterpret: Consider reporting ceftriaxone as resistant ntibiotic Category mpicillin moxicillin-clavulanate Piperacillin-tazobactam Cephalothin Ceftriaxone Ceftazidime Cefepime Cefoxitin rtapenem Gentamicin mikacin Ciprofloxacin rimethoprim-sulfamethoxazole
Limitations High complexity of resistance mechanisms Limited information about some mechanisms of resistance Multifactorial multiresistance Oversimplification of interpretative reading Mistakes when deducing mechanisms of resistance
Part hree XCPOL PHOYP
X C P O L P H O Y P esistance in a species where resistance has not been seen or is rare may change with time may also be regional or national differences
X C P O L P H O Y P esistance in a species where resistance has not been seen or is rare errors in identification or susceptibility testing send the isolate to a reference laboratory for independent confirmation
xamples X C P O L P H O Y P treptococcus pyogenes resistant to penicillin taphylococcus aureus resistant to vancomycin Haemophilus influenzae resistant to any thirdgeneration cephalosporin, carbapenems, and fluoroquinolones
xamples X C P O L P H O Y P naerobes resistant to metronidazole eisseria gonorrhoeae resistant to third-generation cephalosporin nterobacteriaceae resistant to carbapenems
HOW O B XP
CU patient 28 days in hospital oxidase negative non-fermentative Gramnegative bacillus
ntibiotic Zone (mm) esult moxicillin-clavulanate 6 Piperacillin-tazobactam 6 Ceftriaxone 6 Ceftazidime 26 Cefepime 18 mipenem 6 rtapenem 6 Meropenem 6 mikacin 6 Gentamicin 6 Ciprofloxacin 30 rimethoprimsulfamethoxazole 35 CU patient 28 days in hospital oxidase negative non-fermentative Gramnegative bacillus What is the likely organism? How would you report susceptibility to: ceftazidime imipenem ciprofloxacin
nterobacter cloacae ntibiotic Zone (mm) esult 6 Cefoxitin 6 Ceftriaxone 27 Ceftazidime 26 Cefepime 24 mipenem 24 rtapenem 23 Meropenem 24 Ciprofloxacin 25 moxicillinclavulanate rimethoprimsulfamethoxazole 20 solate from blood culture Patient with suspected ventilatorassociated pneumonia
nterobacter cloacae ntibiotic Zone (mm) esult 6 Cefoxitin 6 Ceftriaxone 27 Ceftazidime 26 Cefepime 24 mipenem 24 rtapenem 23 Meropenem 24 Ciprofloxacin 25 moxicillinclavulanate rimethoprimsulfamethoxazole 20 solate from blood culture Patient with suspected ventilatorassociated pneumonia How would you report susceptibility to: ceftriaxone cefepime imipenem
FCL LLGC
Computerised expert modification Disc susceptibility MC equivalent dagio Phoenix Biomic Vitek Microscan
Vitek Changed cefepimeto esistant
Lab nformation ystem lerts
he eal xpert
ummary ystems vary in accuracy design update frequency ee Winstanley, Courvalin P. xpert ystems in Clinical Microbiology. Clin Microbiolev. 2011; 24(3):515 56.
Conclusions ome resistant organisms may need supplemental methods to detect usceptibility testing can be complicated esistance mechanism or tested MC? ot yet quite sure.