Optimizing MALDI-TOF Use Clinical Impact Laboratory Impact Christine C. Ginocchio, PhD, MT (ASCP) Clinical Professor of Medicine Hofstra North Shore-LIJ School of Medicine, NY VP, Global Microbiology Affairs, biomerieux VP, Global Medical and Scientific Affairs, BioFire Dx
Power Ionising Vacuum Negative MALDI-TOF Mass Spectrometry 2
CLINICAL APPLICATIONS BEYOND BACTERIAL ISOLATE IDENTIFICATION DIRECT DETECTION AND DIRECT AST FROM POSITIVE BLOOD CULTURES
Gram stain impacted 42 cases (20.8%) MALDI-TOF ID led to a modification of empirical therapy in 71 of all 202 cases (35.1%), and in 16 of 27 cases (59.3%) of monomicrobial bacteremia caused by AmpC-producing Enterobacteriaceae. The most frequently observed impact was an early appropriate broadening of the antibiotic spectrum in 31 of 71 cases (43.7%). In total, 143 of 165 episodes (86.7%) of monomicrobial bacteremia were correctly identified at genus level by MALDI-TOF. 4
In 202/259 bottles where VITEK MS (Saramis database) was able to generate an ID, 189 (93.6%) were correct to the species level, whereas the IDs provided for 7 isolates (3.5%) were incorrect. 5
VITEK MS:1242 Bottles/901 Isolates Achromobacter sp. Acinetobacter spp. (2) Aeromonas sp. Citrobacter spp. (2) E. coli Enterobacter spp. (2) H. influenzae Klebsiella spp. (2) Morganella morganii Pasturella multocida Proteus spp. (3) Providencia spp. (2) Pseudomonas spp. (3) Serratia spp. (2) Steno. maltophilia (species number) Abiotrophia sp. Actinomyces spp. (2) AHS (10) Bacteroides spp. (7) Beta strep groups B, C, G Clostridium spp. (2) CNS (7) Fusobacterium spp. (2) Enterococcus spp. (3) Peptostreptococcus (1) Micrococcus luteus Prevotella buccae Staph aureus Stomatococcus sp. Strep. bovis Strep. pneumoniae Candida spp. (6) Bacillus spp. (2) C. neoformans Corynebacterium spp. (3) Rhodotorula spp. (2) Eubacterium sp. Trichosporon asahii Lactobacillus acidophilus Listeria monocytogenes Nocardia spp. (2) Rothia denticarosa Off label use: Laboratory validated 6
Blood ID using VITEK MS RUO, MS IVD and Combination of MS IVD and MS RUO Total ID ID Family ID Genus ID Genus ID Genus No ID N=632 N (%) only only and species and/or species N (%) N (%) N (%) N (%) N (%) MS RUO 80.1% 1.9% 3.0% 75.2% 78.2% 19.9% MS IVD 84.7% 0.0% 0.2% 84.5% 84.7% 15.3% MS IVD/ MS RUO 86.4% 0.0% 0.6% 85.8% 86.4% 13.6% Discordant between MS RUO and MS IVD were to species level 2 Staph delphini/intermedius (RUO) called Staph pseudointermedius (IVD) 2 Staph warneri (RUO) called Staph pasteuri (IVD) In both cases the two choices reside in the same taxonomic groups. One Strep mitis/oralis (RUO) was called Strep pneumoniae (IVD) confirmed to be Strep pneumoniae by 16s rrna gene sequencing Off label use: Laboratory validated 7
Comparison of VITEK MS Blood ID to ID of Isolates by Conventional Methods ID Family ID Genus ID Genus and ID Genus No N=546 only only species and/or species Correlation a N (%) N (%) N (%) N (%) N (%) MS IVD/RUO 0.0% 0.9% 99.1% 100.0% - Conventional 0.0% 22.3% b 77.7% b 100.0% - Correlation 0.4% 23.3% b 76.2% b 99.4% 0.2% a a 1 Corynebacterium sp. was called Actinomyces neuii (IVD/RUO) and confirmed to be Actinomyces neuii by 16s rrna gene sequencing b For conventional testing, coagulase negative Staphylococcus spp., Bacillus spp., Corynebacterium spp. and alpha hemolytic streptococci from single blood cultures are not routinely identified to species level Off label use: Laboratory validated 8
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Off label use: Laboratory validated 12
Performance of Direct Testing 13
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Beta lactamase with cefotaxime Discrimination between E. coli strains that were R or S to aminopenicillins and R to 3rd-generation cephalosporins in Enterobacteriaceae that constitutively produced class C lactamases had a with a sensitivity and a specificity of 100%. Discrimination was more difficult in species expressing class A -lactamases, as these enzymes can generate false-positive results. Thus, the sensitivity and specificity for this group were 100% and 91.5%, respectively. Cefotaxime 16
Game Changers: Time to Accurate ID Time to ID: hours versus weeks Accuracy and subspecies determinations 17
Tested 140 strains representing 17 genera and 22 species Results compared to sequencing/molecular probes 18
Differentiate closely related species and species within a genus 19
Mather et al. JCM 2014:52;130. 20
WORKFLOW IMPROVEMENTS
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Omai Garner, PhD, D(ABMM) Assistant Clinical Professor Department of Pathology and Laboratory Medicine Associate Director of Clinical Microbiology Traditional anaerobe identification and AST Total time for Identification 5 days Total time for Identification and Sensitivities amount of time on possible inappropriate therapy 7 days MALDI-TOF Total time for Identification and sensitivities (anaerobic coverage for treatment) 2 days Large clinical impact 3 day improvement in turn around time for patient Lab impact Saves CLS time on the bench, no aero tolerance test (multiple plates), no rapid ANA or other biochemical tests May allow a lab to offer 7 day a week coverage ASM Annual Meeting, Boston 2014 23
Hands on Time/Time to Results Microscan/Conventional Set Up: 48 samples Order: 30 sec/panel Set up: 1 min/panel Total hands on time: 72 min Microscan/Conventional Time to ID/48 samples Read time: 18-24-36-48 hr Microscan/Conventional Time to ST 18 to 48 hr MALDI-TOF: Set Up: 48 samples/3 calibrators Write the directory of samples:5 min Prepare full slide/calibrators: 25 min Create template in the computer with ID and lot numbers: 5 min Place slide into instrument: 1 min Total hands on time: 36 min MALDI-TOF Time to ID Load and re-pressurize: 7 min Read calibrators and 1 acquisition zone: 15 min Time to first results: 22 min / next 16 results: 15 min Complete 48 wells and calibrator x6: 52 +/- 2 min Vitek II Time to AST 6 to 24 hr 24
Change in Laboratory Workflow Shift 1: 11 PM to 7AM Blood Cultures Gram stains Processing Day 1: Shift 2: 6 AM to 5 PM 4 hour work increments Day 2: Shift 2 Release 6 AM to 10 AM, 10 AM to 2 PM ID and AST results available 20-24 hr: 75% after rounds: 18-24 hr Day 1: Shift 3: 4 PM to 1 AM 4 hour work increments Day 2: Shift 3: Release 4 PM to 8 PM, 8 PM to 12 AM ID and AST results available 20-24 hr: results after rounds: 8-16 hr 25
Change in Laboratory Workflow Shift 1: 11 PM to 7AM Blood Cultures Gram stains Processing Day 1: Shift 2: 6 AM to 5 PM 4 hour work increments Day 1: Shift 3: Release 4 PM to 8 PM, 8 PM to 12 AM ID: 1.5 hr: AST results available 8-12 hr: 95% before rounds rounds Day 1: Shift 3: 4 PM to 1 AM 4 hour work increments Day 2: Shift 1, 2: Release 4 AM to 10 AM, 10 AM to 2 PM ID: 1.5 hr: AST results available 8-12 hr: 12 hours earlier 26
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