powerpoint presentation · •vitek ms ivd 2.0 –91.2% sppid; bruker ruo 88% id •identical...
TRANSCRIPT
11/12/2016
1
BETTER, FASTER, STRONGER:
CLINICAL MICROBIOLOGY IN THE
ERA OF MALDI-TOF MASS
SPECTROMETRY
Susan Butler-Wu, Ph.D., D(ABMM), SM(ASCP)
Associate Professor
Keck School of Medicine of USC
Los Angeles, CA
Timeline of diagnostic microbiology
1677
Van Leeuwenhoek observes
“animalcules”
1881
First bacterial culture
(Robert Koch)
1882
Gram stain
(Christian Gram)
1884
Acid-fast stain
(Paul Ehrlich)
1887
Petri Dish Invented
(William Petri)
1928
Penicillin Discovered
(Alexander Fleming)
1977
DNA Sequencing
(Sanger & Gilbert)
1983
PCR Invented
(Kary Mullis)
1949
Poliovirus grown in test tube
cultures of human tissues (Enders, Weller and
Chapman Robbins)
1995
First complete bacterial
genome sequenced (Venter, Smith & Fraser)
Disk Diffusion
(Kirby, Bauer, Sherris & Turck)
1990
Continuous monitoring blood
culture systems
1997
Automated biochemical ID
1966
2000
First launch of NGS
technology
2006
First launch of a MALDI
microbial ID system
2011
First launch of “syndromic”
infection testing
2014
First CLIA-waived
molecular test
Dingle TC & SM Butler-Wu. 2013. Clin. Lab. Med. 33(3):589-609
MALDI-TOF-MS = Matrix
Assisted Laser Desorption
Ionization Time-of-Flight Mass
Spectrometry
Apply matrix solution
1.
2.
3.
Anaerobic
bacteria
Select pure colony
Full protein
extraction
OR
Apply colony to
target plate
Overlay with
formic acid
Apply supernatant to
target plate
Gram-negative
bacteria
Select pure colony
1.
Apply colony to
target plate
2.
Direct analysis
Analyze in MALDI-TOF MS instrument
1.
2.
3.
Select pure colony
Gram-positive bacteria
and yeast
Overlay with
formic acid
Full protein
extraction
Apply
supernatantto target plate
Apply colony to
target plate
Direct analysis
OR
OR3.
Bourassa L & SM Butler-Wu. 2015. In: “Methods in Microbiology:Current and emerging technologies for the diagnosis of microbial infections”
Major advantage: Much faster TAT
Dingle TC & SM Butler-Wu. 2013. Clin. Lab. Med. 33(3):589-609
Real-world TAT data
• 952 prospective bacterial & yeast isolates1
• >85% isolates ID’d on first day of analysis with MALDI
• 9.4% isolates ID’d on first day with conventional methods
• Average time to identification reduced by 1.45 days
• >400 consecutive bacterial & yeast isolates compared
pre- & post-MALDI implementation2
FINAL ID: 60.50 h vs.
49.98 h
1Tan KE et al. J. Clin. Microbiol. 2012. 50(10), 3301-33082Charnot-Katsikas A et al. J. Med. Microbiol. 2014. 63(Pt 2):235-41
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THE MAJOR PLAYERS…
Bruker MALDI Biotyper
• CA System - FDA-cleared
• 280 species (Gram-positive,
Gram-negative, yeast &
anaerobes)
• Separate Research Use
Only (RUO) database
• >2,200 species (371 genera)
• Separate RUO
mycobacterial and fungal
databases
In the red corner…
Identification by MALDI-TOF MS: The
Bruker method
Main Spectrum (MSP)
Match score >2.0 = definitive ID
Match score >1.7 = ID to genus level
bioMerieux VITEK MS
• IVD v2.0 - FDA-cleared
• 193 species (Gram-positive,
Gram-negative, yeast &
anaerobes)
• RUO Saramis v4.12
Database (available with
VITEK MS Plus)
• >1300 species (>300 genera),
which also includes
mycobacteria and filamentous
fungi
In the blue corner…
Identification by MALDI-TOF MS: The
bioMerieux method
Unimodal Species
Closely Related Species
Multimodal Species
Match to superspectrum = definitive ID
Match to multiple individual spectra = definitive ID
Weighted Bin Matrix
11/12/2016
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Head-to-head: Routine bacterial & yeast
isolates• Initial studies showed superior performance of the Bruker
Biotyper vs. VITEK MS• Identification rates of 94.4-95.3% vs. 88.8-93.4%
• Database enhancements led to improved performance 92.7-93.9% vs. 93.2-93.7%
• Performance for anaerobes• 61.3% (Biotyper) vs. 75.3% (VITEK MS) spp. identification rates3
• Bacteroides spp. > problematic for VITEK MS
• Fusobacterium spp. > problematic for Biotyper
• VITEK MS IVD 2.0 – 91.2% spp ID; Bruker RUO – 88% spp ID
• Identical identification rates for unusual or difficult to ID• 85.1% correct species ID for both systems
1Carbonelle E et al. J Microbiol Methods.2012. 89(2):133-1362Cherkaoui A et al. J. Clin. Microbiol. 2010. 48(4): 1169-11753Martiny D et al. J. Clin. Microbiol. 2012. 50(4), 1313-13254Deak E et al. DMID. 2015. 81(1), 27-335McElvania-Tekippe E et al. J. Clin. Microbiol. 2013. 51(5), 1421-1427
What about IVD cleared versions?
• Biotyper CA system (1st claim)
• 2,263 GN rods (23 genera, 61 spp.)
• 98.2% identified correctly to spp. level
• Only 71% of H. influenzae correctly identified
• H. haemolyticus misidentified as H. influenzae
• Addition of H. haemolyticus strains known to improve
performance - 99.6% accurate for H. influenzae2
• Performance of most recent claim not yet published…
• 98.9% identified to genus or species level per FDA
1Faron ML et al . PLoS One. 2015. 10(11):e01413502Bruin JP et al. EJCMID. 2014. 33(2):279-84
What about IVD cleared versions?
• VITEK MS IVD 2.0
Category No. isolates ID to spp. MisID Reference
Gram-positive 1,147 92.8% 1.6% Rychert J,
2013
Enterobacteriaecae 965 96.1% 0.6% Richter SS,
2013
Non-Enterobacteriaecae 558 77.8% 1.6% Manji R,
2014
Fastidious, aerobic 226 96% 4% Branda JA,
2014
Anaerobes 651 91.2% 3.2% Garner O,
2014
Yeast 852 96.1% 0.6% Westblade
LF, 2013
A cautionary tale…
• 62 yo male (vacationing
in Thailand) suffered a
heart attack &
hospitalized for 1 week
• Had been hiking in rural
areas
• 1 month after return to
Seattle, presented to
PCP with UTI symptoms
• Urine sent for culture
• 24 hours – NG on MAC,
growth on BAP
• 48 hours – growth on
MAC & BAP
Dingle TC et al. J Clin Microbiol. 2014. 52(9):3490-1
Image: CDC PHIL
What happened next…
Burkholderia thailandensis
(SV= 1.864)
Oxidase
Result
This was ultimately identified by the WA state PH
Laboratory as B. pseudomallei
• 21 employees exposed; both “high risk” & “low risk”
exposures
MALDI-TOF and select agents
• Bruker Biotyper: Security-Relevant database (53 spectra
from 6 select agents; RUO)
• All 18 Francisella & Brucella isolates id’d to at least genus level
• 1 B. pseudomallei id’d as B. mallei
• 1 B. pseudomallei id’d as B. pseudomallei
• “no reliable identification” for all Brucella & Francisella isolates when
tested against Biotyper reference library
• VITEK MS: IVD database has B. anthracis & Y. pestis (not
cleared)
• RUO database has others, including B. pseudomallei
Cunningham & Patel. J Clin Microbiol. 2013. 51(5): 1639
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Other misidentification issues…
• Bruker Biotyper• S. pneumoniae vs. viridans streptococci
• S. pseudopneumoniae vs. S. pneumoniae
• Shigella vs. E. coli
• N. meningitidis vs. N. polysaccharea
• VITEK MS• Shigella vs. E. coli
• Kocuria rhizophila misidentified as Corynebacterium jeikeium
• Anaerobic GP’s misidentified as coagulase-negative staphylococci
• S. pseudopneumoniae misidentified as A. schaalii
• Other issues• Salmonella – not reliable for serotyping
• Difficulty resolving members of complexes or groups (e.g. B. cepacia, Bacillus cereus)
Cunningham SA et al. J Clin Microbiol. 2014. 52(6):2270-1Van Prehn J et al. DMID. 2016.
Alby K et al. J Clin Microbiol. 2015. 53(1):360-1
A special word on the Actinomycetaceae…
• 158 strains, isolated over 8 years
• Tested with both VITEK MS IVD v2.0 and Bruker Biotyper IVD
Ferrand J et al. J Clin Microbiol. 2016. 54(3):782-4
The diversity of Actinomyces…
• 115 patients with invasive
Actinomyces infections
• 41% correct spp ID by VITEK MS
IVD 2.0 vs. 16S rDNA
• 13% misidentified with “excellent
ID->99% probability”• Clostridium perfringens
• Escherichia coli
• Kocuria kristinae
• Kytococcus sedentarius
• Arcanobacterium haemolyticum
• Streptococcus mitis
• Geobacillus thermoglucosidasius
• Paracoccus yeei
• Staphylococcus warneri
• Cedecea neteri
Lynch T et al. J Clin Microbiol. 2016 Mar;54(3):712-7
The bottom line…
• MALDI-TOF-MS generally displays equivalent or superior
performance compared with traditional methodologies
System No. Type
Period of
Isolate Collection
Genus
Level
Species
LevelCountry Comparator
Comparator
PerformanceReference
Bruker
Biotyper1013 Bacteria 2 mo 99% 97% France
Phoenix, API,
Biochemical
93.2%
species, 98.4% genus
Bessede,
2011
Bruker
Biotyper468 Bacteria 3 mo 97% 92% Japan
MicroScan,
API, Phoenix
91.5%
species
Sogawa,
2011
Bruker
Biotyper
2781
(927 x3)
Bacteria 1 mo 96% 85% AustraliaVITEK2, API,
BiochemicalNot provided
Neville,
2011
Vitek MS 767 Bacteria 6 wk 95% 87% France VITEK2 Not providedDubois,
2012
Bruker
Biotyper/
Vitek MS
986 Bacteria 3 mo 96%/94% 93%/93% Belgium
Bruker
Biotypercompared to
Vitek MS
N/AMartiny,
2012
Adapted from Patel R, 2013. Clin Inf Dis. 57(4):564-72
MALDI-TOF-MS is cost-effective for
routine organism ID
• Estimated annual cost savings of $102,413 per year1
• 54% less than standard protocol
• Estimated annual reagent cost savings of €26,771 ($34,385)2
• Estimated reagent savings of $69,108 per year3
• 87.8% less than standard protocol
UWMC Pre-MALDI Post-MALDI
Reagents $41,035 $4,376
Labor $87,637 $54,306
Sequencing $29,700 $5,700
Total $158,372 $64,382
• Annual savings of $94,000/year
• Reduced number of routine
bacteria & yeast isolates requiring
sequencing from 300 to 60 per
year
1Tan KE et al. J. Clin. Microbiol. 2012. 50(10):33012Martiny D et al. EJCMID. 2014 33(5):7453Tran A et al. J. Clin. Microbiol. 2015. 53(8):2473-9
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Benefits to patients
• Direct from blood culture ID• 44.6% of pts with improved time to appropriate therapy1
• Decreased all-cause 30-day mortality (21% vs. 8.9%) and annual hospital
cost savings of $2.4 million2
• Blood culture colony identification • MALDI ID of colonies from positive blood cultures3:
• improved time to optimal antibiotic therapy (90.3 vs. 47.3 hours)
• decreased mortality (20.3% vs. 14.5%)
• decreased length of intensive care unit stay (14.9 vs. 8.3 days)
• Both strategies require the involvement of engaged and
empowered antimicrobial stewardship!
1Tamma PD et al. Inf. Cont. Hosp. Epidemiol. 2013. 34(9):9902Perez KK et al. J Infect. 2014. 69(3):2163Huang AM et al . Clin. Inf. Dis. 2013. 57 (9): 1237
Image: www.merivaara.com
• Identification of mycobacteria
• Detection of antimicrobial
resistance
Why do we need to accurately
identify Mycobacterium spp ?
• The Mycobacterium genus consists of >170 species
• Molecular strategies for the direct detection of M.tuberculosis
are not perfect
• Xpert MTB/Rif had a pooled sensitivity of 89% over 22 studies1
• 2x MTB/Rif = 91.1% sensitive for pulmonary TB2
• Culture isn’t going anywhere…
• Important treatment differences for Non-Tuberculous
Mycobacteria (NTM)
• e.g. M. fortuitum vs. M. chelonae
• e.g. M. abscessus subsp abscessus vs. M. abscessus subsp bolletii
• ATS/IDSA recommends to ID clinically significant NTM
isolates to the species level whenever possible3
1Steingart KR et al. Cochrane Database Syst Rev. 2014.1:CD0095932Luetkemeyer AF et al. Clin Inf Dis. 2016. [Epub ahead of print]3Griffith DE et al. Am. J. Respir. Crit. Care Med. 2007. 175:367
How are Mycobacterium spp identified?
• Phenotypic
• Growth characteristics
• Biochemical phenotype
• Pigment production
• Sub-optimal accuracy
• Weeks, Labor intensive
HPLC:
• complicated extraction, not widely available
• Hours, $$
• Molecular methods – Days, $$$
• Mycobacteria
• TB, MAC, M. kansasii and M. gordonae probes
• Sequencing: rpoB, hsp65, 16S rDNA, etc.
Micro Lab 2016
Staff Retreat
Why use MALDI-TOF-MS to identify
mycobacteria?
• Possible advantages over traditional methodologies
• potential for rapid diagnosis after culture positivity
• inexpensive (<$1 per specimen)
• relatively specific
• But some other considerations…
• organism inactivation – TB!!!
• cell wall
• reproducibility/robustness
• amount of biomass required
• databases
Doern & Butler-Wu. 2016. J. Mol. Diagn. 18(6): 789–802
11/12/2016
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• Transfer 1 µl mycobacterial biomass to 300 µl deionized
water and approx. 200 µL of 1 mm silica beads
• Heat at 95oC for 30 min
• Add 900 µl of 100% ethanol and horizontal vortex for 10
min
• Transfer the supernatant to a new tube using a pipette
• Centrifuge 2 min at 13,000 x g, aspirate off as much
ethanol as possible - repeat
• Air dry 10 min
• Add 10 µl of 70% formic acid and mix using the pipette tip
or vortex
• Add 10 µl of 100% acetonitrile and ololvortex for 20-30
sec
• Centrifuge 1 min at 10,000 x g
• Transfer 1 µl supernatant to target plate
UW Extraction Protocol
Mather C A et al . J. Clin. Microbiol. 2014;52:130 Mather C A et al . J. Clin. Microbiol. 2014;52:130
Similar findings in subsequent studies• 157 Mycobacterium isolates from Washington University,
Saint Louis
Wilen CB et al. J. Clin. Microbiol. 2015; 53(7):2308-15
Antimicrobial resistance detection
by MALDI-TOF MS
Image: (Super germ via Shutterstock)
The growing burden of antimicrobial
resistance…
Images: CDC
Threat level of urgent
• Clostrdium difficile
• CRE
• Drug-resistant
Neisseria gonorrhoeae
Threat level of serious:
12 microorganisms listed,
including:
• MDR Acinetobacter &
Pseudomonas
aeruginosa
• Vancomycin-resistant
Enterococci (VRE)
• MRSA
• Drug-resistant
tuberculosis…
The curious story of MRSA & MALDI…
Conflicting earlier reports
regarding ability of MALDI-
TOF MS to distinguish
MRSA and MSSA isolates
Identical spectral profiles
between isogenic SCCmec+
and SCCmec-neg mutants
SzabadosF et al. J Infect. 2012. 65(5):400-5
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Don’t throw the baby out with the
bathwater...
USA100
USA300
This peak is observed only when
direct cell analysis is performed,
and absent if cells undergo
extraction
VRE & MALDI-TOF MS
1Griffin PM et al.J Clin Microbiol. 2012. 50(9):2918-312Nakano S et al. Int J Antimicrob Agents. 2014. 44(3):256-9
vanB+
vanB-
67 consecutively isolated vanB+
E. faecium isolates analyzed1
• Identified 5 peaks of interest
• Prospectively evaluated a
Support Vector Machine (SVM)
model based on these peaks
• Sensitivity of 96.7% and a
specificity of 98.1%
Similar approach for vanA-positive
E. faecium showed 87.5%
sensitivity, 97.3% specificity2
Detection of a blaKPC-containing plasmid
• 2011 outbreak at NIH with
Klebsiella pneumoniae harboring
a pKpQIL plasmid with blaKPC
• 11,109 Da protein present in
blaKPC+ strains from the outbreak1
• Top-down proteomics identified
the 11,109 Da protein as
pKpQIL_p019 (p019)
• p019 detected by MALDI-TOF
MS in 25/26 strains positive for
the pKpQIL plasmid2
Spectra from 18 recultured
blaKPC-positive & blaKPC-negative K. pneumoniae
isolates1Lau AF et al. J Clin Microbiol. 2014. 52(8):2804-122Youn JH et al. J Clin Microbiol . 2016. 54(1):35-42
Detection of enzymatic activity
The diversity of β-lactamasesCategory Enzymes Features
Broad Spectrum TEM-1, TEM-2, SHV-1 Penicillinases - limited activity vs. cephs
Extended Spectrum TEM, SHV variants Active against extended cephs, penicillins
Inhibited by Clavulanic acid, etc.
Extended Spectrum CTX-Ms As above, but < active vs. ceftazidime
Inhibitor-resistant Mostly TEM-1, TEM-2 variants R to inhibitor combos
Serine carbapenemases KPC
SME, NMC-A, IMI-1
KPC – plasmid
• Detection issuesSME – S. marcescens (chomosomal)
NMC - E. cloacae (chromosomal)
Metallo-β-lactamase
(carbapenemases)
VIM – plasmid, P. aer & now enterics
IMP- plasmid, enterics & non-enterics
NDM-1 - plasmid
Others - chromosomal
R to carbapenems!!!
• Detection issues
Cephalosporinase Many – CMY, LAT, MIR, FOX, etc. Chromosomal
• not inhibited by clavulanic acid, etc.• Inducible – e.g. Enterobacter, Citrobacter
Plasmid
Oxacillin-hydrolyzing OXA Integrons, plasmids
Resistance to variety of penicillinsESBL-phenotype in P.aer = OXA-11, OXA-14, OXA-20
Some can hydrolyze carbapenems e.g. OXA 24-40,
OXA-48
Detection of carbapenemase activity by
MALDI-TOF-MS
Burckhardt & Zimmerman. JCM. 2011. 49 (9): 3321-3324
• Cheap
• <$1.50/reaction
• Fast
• 1-2 hours,
depending on
enzyme
• BUT only capable of
detecting hydrolysis-
based resistance
• Subsequent studies have also adapted the method to cephalosporins and tested
a variety of carbapenemases and beta-lactamases
• Detection of cefotaxime-resistance by MALDI directly from blood cultures
showed 100% sensitivity and 92% specificity for Enterobacteriaceae**Jung et al. JCM. 2014. 52(3): 924–930
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Issue: Lack of standardization between
studies
Mirande C et al. Eur J Clin Microbiol Infect Dis. 2015. 34(11):2225-34
(Imipenem)
(+ Cephalosporinase)
(+ ESBL)
(+ OXA-48)
(+ KPC)
(+ NDM)
300 Da254 Da
Lasserre C et al. J Clin Microbiol. 2015. 53(7):2163-71
1-μl loopful of
bacteria suspended
in 20 μl of 0.5 mg/ml
imipenem solution -
20 min incubation,
37°C
[M/(M + I)] calculated
for 223 clinical strains
(77 carbapenemase-
positive)
ROC analysis: Cut-off
of 0.82 = 99%
sensitive, 100%
specific for 266
clinical isolates (102
carbapenemase-
positive)
Where are we going? The case for
moving beyond peak detection…
Vancomycin-intermediate S. aureus
• Vancomycin is a mainstay in the treatment of serious
MRSA infections
• CLSI MIC breakpoints:
• S ≤2µg/mL, I=4-8µg/mL, R ≥16µg/mL
• VISA is associated with both mutation & transcriptional
changes
• plethora of genes
• VISA strains are associated with
• Thickened cell wall
• Decreased autolytic activity
• Decreased cross-linking between murein monomers
• Increased proportions of non-amidated muropeptides
The hVISAproblem
• “h” is for heterogeneous
• resistant population present at frequency of ≤10-5-10-6
• but susceptibility testing is performed using an inoculum of 5x104
CFU/ml
• Population analysis profile PAP is considered the gold
standard for hVISA detection
• hVISA PAP/AUC ≥0.9 vs. control strain (Mu3)
• time-consuming & labor-intensive
Does hVISA matter clinically?
• Retrospective, multicenter study – 2004-2012• 122 pts with MRSA BSI – 61 matched pairs (hVISA and VSSA)
• 11x greater odds of
vancomycin failure
• Increased LOS by
median of 8 days
Casapao AM et al. AAC. 2013. 57:4252
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Comparison of VISA and VSSA by
MALDI-TOF MS
• 16 VISA, 12 VSSA strains
• Identified peaks present in
≥75% of either group (i.e.
VISA or VSSA) with a
coefficient of variance (CV)
<50% within that group
• 22 peaks that maximized the
separation of VISA and VSSA
isolates
Mather CA et al. J Clin Microbiol. 2016. [Epub ahead of print]
Extended analysis to 21 VISA & 38 VSSA
isolates
Forward stepwise regression
performed on these 60 peaks
identified 14 peaks that best
separated the VISA and VSSA
isolates
Mather CA et al. J Clin Microbiol. 2016. [Epub ahead of print]
Reliable separation of VISA and VSSA
using SVM analysis
• Overall classification accuracy
of 98%
Mather CA et al. J Clin Microbiol. 2016. [Epub ahead of print]
• Inclusion of hVISA in SVM
algorithm: Overall
classification accuracy of 89%
What about antimicrobial susceptibility?
• MBT-ASTRA
• Quantitative MALDI
• Internal quantitative standard in combination with normalization to
maximum peak allows direct comparison of peak intensities –
“relative growth values”
• 108 Klebsiella isolates – 97.3% sensitive & 93.5% specific
compared with E-test (MIC method)
• Media already frequently used in clinical lab (BHI)Susceptible strain Resistant strain
Lange C et al. J Clin Microbiol. 2014 52:4155–4162
MBT-ASTRA: MIC of Acinetobacter
baumannii isolates vs. E-test MIC
• 3.5 hour
incubation
• [Tobramycin]
range tested =
2–256 μg/mL
• BUT assay has
to be optimized
for every bug-
drug combo…
Sparbier K et al. Methods. 2016. [Epub ahead of print]
Conclusions
• MALDI-TOF MS is revolutionizing the practice of clinical
microbiology
• Allows us to see microorganism species we never knew
we were actually seeing!
• MALDI-TOF is not infallible – not a substitute for skilled
microbiologists
• Identification of mycobacteria by MALDI-TOF will reduce
the need for sequence-based identification
• Detection of resistance & MALDI-TOF: Watch this
space…
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10
Acknowledgements
• University of Washington
• Cheryl Mather, M.D.
• Brian Werth, Pharm.D.
• Susan Turner
• Lauren Curtis
The UW extraction protocol effectively
inactivates Mycobacterium spp.• Inoculated Middlebrook 7H11 agar and VersaTREK Myco
bottles with 100 µl of sample after the inactivation step
• Tested the following:• M. tuberculosis (5 strains)
• M. chelonae
• M. kansasii
• M. abscessus
• M. fortuitum
• Result: No growth i.e. inactivation achieved