Vitek 2 – A User Experience. BSAC Standardized Disc Susceptibility Testing Method - User Group Meeting. Cardiff, 13 May 2010 Vitek 2 – A User Experience. Nathan Reading Senior Biomedical Scientist Sandwell and West Birmingham Hospitals NHS Trust

Our Department Covers 3 Hospital Sites Totalling 1000 beds Serves approx 0.6 million people Specialist Supra-Regional Eye Hospital Birmingham Treatment Centre Microbiology department is home of BSAC Standardized Method Development Centre

Our Department Long term user/initial developer of BSAC Standard Method Research interests in mechanisms of antimicrobial resistance and sensitivity testing Approx 6 WTE’s Implemented automated system – Vitek 2 XL June 2009

1 Year B.V. (before Vitek....) Previously.... Disc susceptibilities for >90% isolates Urines Blood Cultures (Direct and Repeats) Respiratory Ocular General – swabs etc Agar Dilution MIC’s All Pseudomonads Resistant gram negatives Ad-hoc organism/difficult infections Gradient Tests Difficult organisms Adhoc testing/confirmations

1 Year B.V. (before Vitek....) Staffing required.. 1 Senior BMS W.T.E. 2x BMS W.T.E. 0.5 MLA W.T.E. Daily/Weekly Tasks Reading Plates/Setting Up Disc Susceptibility Plates and pouring Agar Dilution Plates/Preparing Antibiotic Stocks and Dilutions/Setting up MIC plates/Reading MIC Plates. Working Day 8am-5pm Weekday 8am-12pm Saturdays (All sensitivities bar MIC’s read, all sensitivities put up bar urinary isolates) 8am-1pm Sundays (Only Blood Culture and MRSA sensitivities setup/read)

Sensitivity testing 1 Year AV (after Vitek...) 1 x Senior BMS WTE 1x BMS WTE 0.6 xMLA WTE Reduced staff overhead Senior BMS freed to look after our organism collection All sensitivity testing complete >90% time by 4pm Sensitivity testing ready for release to clinician by 10-11am We do not release same day sensitivity testing.... Do not wish to retract incorrect reports Our working days structure currently means that cards not going onto Vitek until mid morning earliest

Sensitivity testing 1 Year AV Gram negatives UTI Use Chromogenic Media E.coli – treated as E.coli, Vitek Sens Coliform group – Vitek Sens and Automated ID also Systemic -Fermenters Automated ID and Sensitivity Test Non fermenters Automated ID or Basic Manual ID Automated Sensitivity Test Blood Cultures Direct disc susceptibility – in-house dilution protocol Repeats by Vitek

Sensitivity testing 1 Year AV Gram positives Staphylococci Vitek Sensitivity Manual ‘traditional’ ID API/Vitek GP Card for discrepant organisms Enterococci Antibiogram/API/Vitek GP card if speciation needed Beta Haem Streptococci Vitek (Group B) and Discs (All others) Fastidious Organisms Discs!

Issues - Flexability Card ‘make up’ will never perfect for every user Bespoke cards can be made for individuals For our UTI’s No Amikacin on UTI card – only Gent We now disc test Amikacin on Gent I/R Aminoglycoside rules cant work properly No Mecillinam Our clinicians want Mecillinam on all Trim R isolates of E.coli/Kleb/Proteus can be 30% isolates!

Issues – Antibiotic Concentrations Rifampicin Card tests at 0.25,0.5 and 2mg/L Calling range 0.25-4mg/L EUCAST/BSAC ‘S’ cut off = 0.06mg/L ‘I‘= 0.12-0.5 ‘R’ =>0.5 Card does not test low enough to determine S using BSAC/EUCAST breakpoints Recent card revision did not solve this Now need to disc test on ad-hoc basis if clinicians require result

Issues – Antibiotic Concentrations Mupirocin Card tests 1mg/L Calling range 2-8mg/L! BSAC ranges S= ≤4 I= 8-256 R >256 Need to disc test to differentiate I from R Mupirocin decolonisation may still work if Intermediate Recent revision to cards did not solve this.....

Detection of resistance Detection of Hyperproduction of K1 enzyme in Kleb oxytoca No Aztreonam on UTI Card AST N144 Need to rely on Inhibitor Resistance and Cefotaxime which can be variable Offline Synergy Test Cefpodoxime/Cefpodoxime+Clav/Cefpodoxime+Clav+Boronic Acid Aztreonam disc testing

Detection of resistance Detection of AmpC

Detection of AmpC Cefoxitin Resistant 3rd Gen Ceph’s = S Check ID Some Chromogenic agars mis-identify Citrobacter species (may have natural AmpC) Check ESBL/Confirmation Test Cefpodoxime/Cefpodoxime+Clav/Cefpodoxime+Clav+Boronic Acid If negative synergy – probable impermeability/porin loss If positive synergy with Boronic Acid/Clav/Cefpodozime = AmpC

Detection of Resistance Detection of ESBL Compared 296 urinary isolates screened with HMRZ -86 a chromogenic 3rd gen Cephalosporin Vitek missed 11 ESBL producers out of a total of 42 Situation improved a little on software update ?algorithms changed Still misses some low expression of ESBL

Solution ? All of the missed isolates (ESBL&AmpC) reduced zone to Cefpodoxime 10ug disc ?Need a Vitek card containing Cefpodoxime 18 missed isolates E.coli/Klebsiella 10 ESBL Missed with routine card 7 AmpC Missed with routine card 1 K1 K oxytoca (included for interest)

Routine Method Findings Solution ? Isolate ID CPD Zone/mm Routine Method Findings AES Findings Cefpod Ceftaz Ceftriax Escherichia coli 17 ESBL acquired penicillinase >8 ≤1 10 AMP C Inconsistent 14 2 Acquired Penicillinase 15 0.5 Klebsiella pneumoniae ACQ Penicillinase + Impermeability (Cephamycins), Impermeability (Cephamycins) <0.25 11 amp c Klebsiella oxytoca 18 ?K1 hyper high level natural penicillinase <1 ESBL (ctx-m), high level natural penicillinase 21 ACQ Penicillinase 13 ampc Acq Penicillinase esbl 4 12 Acq penicillinase 16 *BSAC Cefpodoxime ‘S’ cut off 1mg/L

Solution ? 16/18 isolates all had MIC for Cefpodoxime >1mg/L (BSAC breakpoint) Include Cefpodoxime on card? With or without CAZ,CTX?

Detection of Resistance What is this isolate? System highlights MRSA as possible mechanism – changes Cefoxitin result from Negative to POSITIVE

Solution ? All isolates showing this change PBP 2’ Latex (Oxoid/Mast) 20 minute test If +ve therefore MRSA If –ve need to rule out MRSA still. Cefoxitin 10 disc on IsoSensitest MecA PCR Our own mini study – partially complete 20 isolates Oxacillin ‘R’ / Cefox Screen Changed to +ve 10 strains MecA negative (Internal control Nuc +ve = S.aureus) All 10 PBP 2’ Latex Negative

Difficult isolates Mucoid isolates – esp Pseudomonads Difficult to get a smooth inoculum May give false resistance/susceptibility Need a plan B MIC? Gradient Test? Discs?

More areas to investigate?

More areas to investigate? Vitek 2 Implentaton New Cards Software upgrade

More areas to investigate? Vitek 2 Implentaton Software upgrade

New and Emerging Phenotypes July 2009 Our first Isolate of NDM-1 Carbapenemase in Klebsiella pneumoniae Detected by Vitek 2 Subsequent challenge with further strains from other centres also detected as expected Isolates with VIM,IMP and KPC isolates also detected. Carbapenemases, the new ESBL?

Summary Automated systems not panacea for solving lack of AST knowledge within laboratory. Some users may find more questions than answers BSAC method still required to fill in the gaps Not just fastidious organisms Some areas could be optimised to enhance detection of important isolates Some cards need to be improved for UK/EUCAST breakpoints

Summary – the positives Reduction of staff overhead Improved speed of results We at City dont make best use of all benefits of automation Can be used to upskill knowledge of AST and mechanisms of resistance Simple to use and well supported by the company.