Name: whole genome sequencing of candida glabrata for detection of markers of antifungal drug resistance
Uploaded: 2017-12-28T15:00:00
Description: Watch this Scientific Journal Video about Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance at JoVE.com

This work was supported by the Centre for Infectious Diseases and Microbiology, Public Health. The authors have not received any other funding for this study. The authors thank Drs Alicia Arnott, Nathan Bachmann and Ranjeeta Menon for their expert advice and assistance with the whole genome sequencing experiment.

No ethical approval was required for this study.
1. Subculture and inoculum preparation for Candida glabrata
<ol>
	<li>Select a panel of C.glabrata isolates to be studied which should also include at least one C. glabrata American Type Culture Collection (ATCC) with known susceptibility pattern.</li>
	<li>Subculture an isolate by touching a single colony using a sterile disposable plastic loop and streaking onto a Sabouraud&#39;s dextrose agar (SDA) plate<sup class...

<ol>
	<li>Beyda, N. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FKS+mutant+Candida+glabrata:+risk+factors+and+outcomes+in+patients+with+candidemia.">FKS mutant Candida glabrata: risk factors and outcomes in patients with candidemia.</a> Clin Infect Dis. 59 (6), 819-825 (2014).</li><li>Chapeland-Leclerc, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acquisition+of+flucytosine,+azole,+and+caspofungin+resistance+in+Candida+glabrata.+bloodstream+isolates+serially+obtained+from+a+hematopoietic+stem+cell+transplant+recipient.">Acquisition of flucytosine, azole, and caspofungin resistance in Candida glabrata. bloodstream isolates serially obtained from a hematopoietic stem cell transplant recipient.</a> Antimicrob Agents Chemother. 54 (3), 1360-1362 (2010).</li><li>Glockner, A., Cornely, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Candida+glabrata-unique+features+and+challenges+in+the+clinical+management+of+invasive+infections.">Candida glabrata-unique features and challenges in the clinical management of invasive infections.</a> Mycoses. 58 (8), 445-450 (2015).</li><li>Pfaller, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Frequency+of+decreased+susceptibility+and+resistance+to+echinocandins+among+fluconazole-resistant+bloodstream+isolates+of+Candida+glabrata.">Frequency of decreased susceptibility and resistance to echinocandins among fluconazole-resistant bloodstream isolates of Candida glabrata.</a> J Clin Microbiol. 50 (4), 1199-1203 (2012).</li><li>Lewis, J. S., Wiederhold, N. P., Wickes, B. L., Patterson, T. F., Jorgensen, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+emergence+of+echinocandin+resistance+in+Candida+glabrata+resulting+in+clinical+and+microbiologic+failure.">Rapid emergence of echinocandin resistance in Candida glabrata resulting in clinical and microbiologic failure.</a> Antimicrob Agents Chemother. 57 (9), 4559-4561 (2013).</li><li>Klevay, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapy+and+outcome+of+Candida+glabrata+versus+Candida+albicans+bloodstream+infection.">Therapy and outcome of Candida glabrata versus Candida albicans bloodstream infection.</a> Diagn Microbiol Infect Dis. 60 (3), 273-277 (2008).</li><li>Arendrup, M. C., Cuenca-Estrella, M., Lass-Florl, C., Hope, W., Eucast, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EUCAST+technical+note+on+the+EUCAST+definitive+document+EDef+7.2:+method+for+the+determination+of+broth+dilution+minimum+inhibitory+concentrations+of+antifungal+agents+for+yeasts+EDef+7.2+(EUCAST-AFST).">EUCAST technical note on the EUCAST definitive document EDef 7.2: method for the determination of broth dilution minimum inhibitory concentrations of antifungal agents for yeasts EDef 7.2 (EUCAST-AFST).</a> Clin Microbiol Infect. 18 (7), 246-247 (2012).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reference+Method+for+Broth+Dilution+Antifungal+Susceptibility+Testing+of+Yeasts.">Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts.</a> Clinical and Laboratory Standards Institute. , (2012).</li><li>Arendrup, M. C., Pfaller, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Danish+Fungaemia+Study,+G.+Caspofungin+Etest+susceptibility+testing+of+Candida+species:+risk+of+misclassification+of+susceptible+isolates+of+C.+glabrata+and+C.+krusei+when+adopting+the+revised+CLSI+caspofungin+breakpoints.">Danish Fungaemia Study, G. Caspofungin Etest susceptibility testing of Candida species: risk of misclassification of susceptible isolates of C. glabrata and C. krusei when adopting the revised CLSI caspofungin breakpoints.</a> Antimicrob Agents Chemother. 56 (7), 3965-3968 (2012).</li><li>Singh-Babak, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+analysis+of+the+evolution+and+mechanism+of+echinocandin+resistance+in+Candida+glabrata.">Global analysis of the evolution and mechanism of echinocandin resistance in Candida glabrata.</a> PLoS Pathog. 8 (5), 1002718 (2012).</li><li>Shields, R. K., Nguyen, M. H., Clancy, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+perspectives+on+echinocandin+resistance+among+Candida+species.">Clinical perspectives on echinocandin resistance among Candida species.</a> Curr Opin Infect Dis. 28 (6), 514-522 (2015).</li><li>Dudiuk, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Set+of+classical+PCRs+for+detection+of+mutations+in+Candida+glabrata+FKS.+genes+linked+with+echinocandin+resistance.">Set of classical PCRs for detection of mutations in Candida glabrata FKS. genes linked with echinocandin resistance.</a> J Clin Microbiol. 52 (7), 2609-2614 (2014).</li><li>Koboldt, D. C., Steinberg, K. M., Larson, D. E., Wilson, R. K., Mardis, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+next-generation+sequencing+revolution+and+its+impact+on+genomics.">The next-generation sequencing revolution and its impact on genomics.</a> Cell. 155 (1), 27-38 (2013).</li><li>Barzon, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+sequencing+technologies+in+diagnostic+virology.">Next-generation sequencing technologies in diagnostic virology.</a> J Clin Virol. 58 (2), 346-350 (2013).</li><li>Didelot, X., Bowden, R., Wilson, D. J., Peto, T. E. A., Crook, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transforming+clinical+microbiology+with+bacterial+genome+sequencing.">Transforming clinical microbiology with bacterial genome sequencing.</a> Nat Rev Gen. 13 (9), 601-612 (2012).</li><li>Koser, C. U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Routine+use+of+microbial+whole+genome+sequencing+in+diagnostic+and+public+health+microbiology.">Routine use of microbial whole genome sequencing in diagnostic and public health microbiology.</a> PLoS Pathog. 8 (8), 1002824 (2012).</li><li>Lipkin, W. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+changing+face+of+pathogen+discovery+and+surveillance.">The changing face of pathogen discovery and surveillance.</a> Nat Rev Microbiol. 11 (2), 133-141 (2013).</li><li>Sintchenko, V., Holmes, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+pathogen+genomics+in+assessing+disease+transmission.">The role of pathogen genomics in assessing disease transmission.</a> BMJ. 350, 1314 (2015).</li><li>Garnaud, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+sequencing+offers+new+insights+into+the+resistance+of+Candida+spp.+to+echinocandins+and+azoles.">Next-generation sequencing offers new insights into the resistance of Candida spp. to echinocandins and azoles.</a> J Antimicrob Chemother. 70 (9), 2556-2565 (2015).</li><li>Sanmiguel, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+sequencing+and+potential+applications+in+fungal+genomics.">Next-generation sequencing and potential applications in fungal genomics.</a> Methods Mol Biol. 722, 51-60 (2011).</li><li>Mardis, E. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validity+of+nucleic+acid+purities+monitored+by+260nm/280nm+absorbance+ratios.">Validity of nucleic acid purities monitored by 260nm/280nm absorbance ratios.</a> BioTechniques. 18 (1), 62-63 (1995).</li><li>Cannon, R. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efflux-mediated+antifungal+drug+resistance.">Efflux-mediated antifungal drug resistance.</a> Clin Microbiol Rev. 22 (2), 291-321 (2009).</li><li>Ferrari, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gain+of+function+mutations+in+CgPDR1.+of+Candida+glabrata+not+only+mediate+antifungal+resistance+but+also+enhance+virulence.">Gain of function mutations in CgPDR1. of Candida glabrata not only mediate antifungal resistance but also enhance virulence.</a> PLoS Pathog. 5 (1), 1000268 (2009).</li><li>Rodrigues, C. F., Silva, S., Henriques, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Candida+glabrata:+a+review+of+its+features+and+resistance.">Candida glabrata: a review of its features and resistance.</a> Eur J Clin Microbiol Infect Dis. 33 (5), 673-688 (2014).</li><li>Garcia-Effron, G., Lee, S., Park, S., Cleary, J. D., Perlin, D. 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&#160; &#160;This study determined feasibility, approximate timelines and precision of WGS-guided detection of drug resistance in C. glabrata. The turnaround time (TAT) for the library preparation and sequencing was four days and reporting of analyzed results one-two days. This compares with at least a similar amount TAT for susceptibility assays from culture plates and Sanger sequencing with significantly higher number of samples. Around 30-90 C. glabrata genomes can be sequenced based on sequencing fl...

Candida glabrata is an increasingly encountered pathogen with importance as a species that exhibits resistance to the azoles as well as more recently, to the echinocandins1,2,3. Unlike the diploid C. albicans, the haploid genome of C. glabrata may allow it to acquire mutations and develop multi-drug resistance more easily. Co-resistance to both drug classes has also been reported4. Hence, early evaluation of antifungal susceptibility and detection of drug resistance in C. glabrata is crucial for correct, targeted therapy as well as in the context of antifungal stewardship to limit drivers of antimicrobial resistance1,5,6. Establishing an efficient workflow to rapidly detect the presence of confirmatory mutations linked to resistance biomarkers in resistant isolates will also help to improve prescribing decisions and clinical outcomes.
Antifungal susceptibility is usually assessed by measuring minimum inhibitory concentration (MIC) which is defined as the lowest drug concentration that results in a significant reduction in growth of a microorganism compared with that of a drug-free growth control. The Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) have standardized susceptibility testing methods in order to make MIC determination more accurate and consistent7,8. However, the utility of antifungal MIC remains limited especially for the echinocandins, in particular with regards to inter-laboratory comparisons where varying methodologies and conditions are used9. There is also uncertain correlation of MICs with response to echinocandin treatment and inability to distinguish WT (or susceptible) isolates from those harboring FKS mutations (echinocandin-resistant strains)10,11. Despite the availability of confirmatory single-gene PCRs and Sanger sequencing of antifungal resistance markers, realization of results is often delayed due to lack of simultaneous detection of multiple resistance markers5,12. Hence, concurrent detection of resistance-conferring mutations in different locations in the genome, enabled by whole genome sequencing-based analysis, offers significant advantages over current approaches.
Whole genome sequencing (WGS) has been successfully implemented to track disease transmission during outbreaks as well as an approach for genome-wide risk assessment and drug resistance testing in bacteria and viruses13. Recent advances in nucleic acid sequencing technology have made the whole genome sequencing (WGS) of pathogens in a clinically actionable turn-around-time both technically and economically feasible. DNA sequencing offers important advantages over other methods of pathogen identification and characterization employed in microbiology laboratories14,15,16. First, it provides a universal solution with high throughput, speed and quality. Sequencing can be applied to any of microorganisms and allows economies of scale at local or regional laboratories. Second, it produces data in a &#39;future-proof&#39;&#160;format amenable to comparison at national and international levels. Finally, the potential utility of WGS in medicine has been augmented by the rapid growth of public data bases containing reference genomes, which can be linked to equivalent data bases that contain additional clinical and epidemiological metadata17,18.
Recent studies have demonstrated the utility of WGS for identification of antifungal resistance markers from clinical isolates of Candida spp.10,19,20. This is mostly due to the availability of high-throughput benchtop sequencers, established bioinformatics pipelines and decreasing cost of sequencing21,22. The advantage of fungal WGS over Sanger sequencing is that WGS allows sequencing of multiple genomes on a single run. In addition, WGS of Candida genomes can identify novel mutations in drug targets, track genetic evolution, and emergence of clinically relevant sequence-types20,22,23. Most importantly, in cases of intrinsic multidrug resistance, WGS can assist in early detection of resistance-conferring mutations prior to treatment selection22,24.
Here, we examined the feasibility of WGS-enabled screening for mutations associated with drug resistance to different classes of antifungal agents. We present a methodology for the implementation of WGS from end-user and diagnostic mycology laboratory perspectives. We included in this analysis three isolate pairs cultured from three separate clinical cases in which in vitro resistance to the echinocandins and 5-flucytosine developed over time following antifungal treatment.

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		<tr height="21">
			<td height="21" style="height:21px;width:275px;">DensiCHECK Plus</td>
			<td style="width:183px;">BioM&#233;rieux Inc</td>
			<td style="width:151px;">K083536</td>
			<td style="width:383px;">Densitometer used for McFarland readings</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Sensititre YeastOne</td>
			<td style="width:183px;">TREK Diagnostic Systems, Thermo Scientific</td>
			<td style="width:151px;">YO10</td>
			<td style="width:383px;">Commercial susceptibility assay plate with standard antifungal drugs.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Fisherbrand Disposable Inoculating Loops and Needles</td>
			<td style="width:183px;">Fisher Scientific, Thermo Fisher Scientific</td>
			<td style="width:151px;">22-363-605</td>
			<td style="width:383px;">Disposable plastic loops can be used directly from package. No flaming required.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Eppendorf Safe-Lock microcentrifuge tubes</td>
			<td style="width:183px;">Sigma Aldrich, Merck</td>
			<td style="width:151px;">T2795&#160;&#160;&#160;</td>
			<td style="width:383px;">Volume 2.0 mL, natural 
			&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">ZYMOLYASE 20T from Arthrobacter luteus</td>
			<td style="width:183px;">MP Biomedicals, LLC</td>
			<td style="width:151px;">8320921</td>
			<td style="width:383px;">Used for cell wall lysis of fungal isolate before 
			DNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Wizard Genomic DNA Purification Kit&#160;</td>
			<td style="width:183px;">Promega&#160;</td>
			<td style="width:151px;">A1120</td>
			<td>Does 100 DNA extractions</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:275px;">Quant-iT PicoGreen dsDNA Assay Kit</td>
			<td style="width:183px;">Thermo Fisher Scientific</td>
			<td style="width:151px;">P7589</td>
			<td style="width:383px;">&#160;Picogreen reagent referred to as fluorescent dye in the protocol. 
			Includes Lambda DNA standard and picogreen reagent for assay.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Nextera XT DNA Sample Preparation Kit</td>
			<td style="width:183px;">Illumina</td>
			<td style="width:151px;">FC-131-1096</td>
			<td style="width:383px;">Includes Box 1 and Box 2&#160; reagents for 96 samples</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:275px;">Nextera XT Index Kit v2</td>
			<td style="width:183px;">Illumina</td>
			<td style="width:151px;">FC-131-2001, 
			FC-131-2002, 
			FC-131-2003, 
			FC-131-2004</td>
			<td style="width:383px;">Index set A 
			Index set B 
			Index set C 
			Index set D</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">NextSeq 500/550 High Output Kit v2&#160;</td>
			<td style="width:183px;">Illumina</td>
			<td style="width:151px;">FC-404-2004</td>
			<td>300 cycles, More than 250 samples per kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">NextSeq 500 Mid Output v2 Kit</td>
			<td style="width:183px;">Illumina</td>
			<td style="width:151px;">FC-404-2003</td>
			<td>300 cycles, More than 130 samples per kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">PhiX Control Kit</td>
			<td style="width:183px;">Illumina</td>
			<td style="width:151px;">FC-110-3001</td>
			<td style="width:383px;">To arrange indices from Index kit in order</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">TruSeq Index Plate Fixture Kit</td>
			<td style="width:183px;"></td>
			<td style="width:151px;">FC-130-1005</td>
			<td>&#160;2 Fixtures</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">KAPA Library Quantification Kit 
			for Next-Generation Sequencing</td>
			<td style="width:183px;">KAPA Biosystems</td>
			<td style="width:151px;">KK4824</td>
			<td>Includes premade standards, primers and MasterMix</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Janus NGS Express Liquid handling system&#160;</td>
			<td style="width:183px;">PerkinElmer</td>
			<td style="width:151px;">YJS4NGS</td>
			<td>Used for DNA dilutions during sequencing</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">&#160;0.8 mL Storage Plate</td>
			<td style="width:183px;">Thermo Scientific</td>
			<td style="width:151px;">AB0765B</td>
			<td style="width:383px;">MIDI Plate for DNA Library cleanup and 
			normalisation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agencourt AMPure XP</td>
			<td style="width:183px;">Beckman Coulter</td>
			<td style="width:151px;">A63881</td>
			<td>&#160;Magnetic beads in solution for library purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Magnetic Stand-96</td>
			<td style="width:183px;">Thermo Fisher Scientific</td>
			<td style="width:151px;">AM10027</td>
			<td>Used for magnetic bead based DNA purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">OrbiShaker MP&#160;</td>
			<td style="width:183px;">Benchmark Scientific</td>
			<td style="width:151px;">BT1502</td>
			<td>96-well plate shaker with 4 platforms</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Hard Shell PCR Plate</td>
			<td style="width:183px;">BioRad</td>
			<td style="width:151px;">HSP9601</td>
			<td>Thin Wall, 96 Well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LightCycler 480 Instrument II&#160;</td>
			<td style="width:183px;">Roche&#160;</td>
			<td style="width:151px;">5015278001</td>
			<td>Accomodates 96 well plate</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Microseal &#39;B&#39; PCR Plate Sealing Film, adhesive, optical&#160;</td>
			<td style="width:183px;">BioRad</td>
			<td style="width:151px;">&#160;MSB1001</td>
			<td>Clear 96-well plate sealers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">CLC Genomics Workbench</td>
			<td style="width:183px;">Qiagen</td>
			<td style="width:151px;">CLCBio</td>
			<td>Software for data analysis, Version 8</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">NextSeq500 instrument</td>
			<td style="width:183px;">Illumina&#160;</td>
			<td style="width:151px;">Illumina&#160;</td>
			<td>Benchtop Sequencer used for next generation sequencing</td>
		</tr>
	</tbody>
</table>

whole genome sequencing of candida glabrata for detection of markers of antifungal drug resistance

Candida glabrata can rapidly acquire mutations that result in drug resistance, especially to azoles and echinocandins. Identification of genetic mutations is essential, as resistance detected in vitro can often be correlated with clinical failure. We examined the feasibility of using whole genome sequencing (WGS) for genome-wide analysis of antifungal drug resistance in C. glabrata. The aim was torecognize enablers and barriers in the implementation WGS and measure its effectiveness. This paper outlines the key quality control checkpoints and essential components of WGS methodology to investigate genetic markers associated with reduced susceptibility to antifungal agents. It also estimates the accuracy of data analysis and turn-around-time of testing.
Phenotypic susceptibility of 12 clinical, and one ATCC strain of C. glabrata was determined through antifungal susceptibility testing. These included three isolate pairs, from three patients, that developed rise in drug minimum inhibitory concentrations. In two pairs, the second isolate of each pair developed resistance to echinocandins. The second isolate of the third pair developed resistance to 5-flucytosine. The remaining comprised of susceptible and azole resistant isolates. Single nucleotide polymorphisms (SNPs) in genes linked to echinocandin, azole and 5-flucytosine resistance were confirmed in resistant isolates through WGS using the next generation sequencing.&#160;Non-synonymous SNPs in antifungal resistance genes such as FKS1, FKS2, CgPDR1, CgCDR1 and FCY2 were identified. Overall, an average of 98% of the WGS reads of C. glabrata isolates mapped to the reference genome with about 75-fold read depth coverage. The turnaround time and cost were comparable to Sanger sequencing.
In conclusion, WGS of C. glabrata was feasible in revealing clinically significant gene mutations involved in resistance to different antifungal drug classes without the need for multiple PCR/DNA sequencing reactions. This represents a positive step towards establishing WGS capability in the clinical laboratory for simultaneous detection of antifungal resistance conferring substitutions.

Thirteen C. glabrata comprising C. glabrata ATCC 90030 and 12 isolates from the Clinical Mycology Reference laboratory (isolates CMRL1 to CMRL12), Westmead Hospital, Sydney were studied (Table 1). These included three pairs of isolates CMRL-1/CMRL-2, CMRL-3/CMRL-4 and CMRL-5/CMRL-6 obtained before and after antifungal therapy with no epidemiological links between them 24 (Table 1).
The M...

Watch this Scientific Journal Video about Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance at JoVE.com

Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance

This study implemented whole genome sequencing for analysis of mutations in genes conferring antifungal drug resistance in Candida glabrata. C. glabrata isolates resistant to echinocandins, azoles and 5-flucytosine, were sequenced to illustrate the methodology. Susceptibility profiles of the isolates correlated with presence or absence of specific mutation patterns in genes.

Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance

Candida glabrata can rapidly acquire mutations that result in drug resistance, especially to azoles and echinocandins. Identification of genetic mutations ...

The overall goal of this study is to implement whole genome sequencing for identification of mutations in genes that confer antifungal drug resistance in Candida glabrata in a diagnostic laboratory. Whole genome sequencing of fungi can make significant contributions in the field of antifungal drug resistance. It allows simultaneous detection of genome-wide mutations in drug-resistant fungi to important antifungal agents.Whole genome sequencing of medically important fungi can also enable the detection and monitoring of outbreaks, of fungal disease, and transmission events in health care settings, as well as emergence of fungal species and clones that clinicians would need to know about. Demonstrating this procedure will be Dr.Rebecca Rockett and Dr.Verlaine Timms both doctoral research fellows from our laboratory. To begin, prepare genomic DNA samples from clinical and commercial strains of Candida glabrata.Then add five microliters of quantified DNA to each well of previously-labeled fresh 96-well hard-shell thin-wall plate. Add 10 microliters of tagmentation buffer and five microliters of amplification buffer to each well. Then use a pipette to gently mix the samples and seal the plate with an adhesive seal, put the plate inside a thermal cycler, and run the appropriate PCR program.When the sample has reached 10 degrees Celsius, immediately add five microliters of neutralization buffer and use a pipette to gently mix the samples. Then seal the plate, and incubate at room temperature for five minutes. After the incubation period, add 15 microliters of Indexing PCR Master Mix to each well.Arrange primer tools in an index plate rack and record the position of the indices on the template. Then place the tagmentation plate containing PCR Master Mix on the index plate rack with the index tubes in the correct order. It is important to arrange the index primer one tubes in horizontal orientation and the index primer two tubes in vertical orientation.It is based on the order and position provided in the index template. Remove the old caps from the index primer tubes and discard them. With a multi-channel pipette, add five microliters of index primers to each well.It is important to perform this step carefully in order to avoid cross contamination between samples and indices. To prevent cross contamination between indices, replace each of the old index tube caps. Finally, seal the plate and run the second PCR program.First transfer the PCR product from the tagmentation plate to a deep-well plate. Vortex a magnetic bead solution and add 30 microliters of beads to each well. Then agitate the plate on a microplate shaker and incubate at room temperature for five minutes.Place the plate on a magnetic stand for two minutes or until the supernatant is clear. Then, without moving the plate, carefully discard the supernatant and add 200 microliters of 80%ethanol. With the plate still on the magnetic stand, incubate for 30 seconds before discarding the supernatant.Repeat the washing process and allow the beads to dry for 15 minutes. Remove the plate from the magnetic stand and add 52.5 microliters of resuspension buffer to the beads. Using a microplate shaker, agitate the plate for two minutes at 1, 800 RPM.Then after the shaker has stopped, incubate the plate at room temperature for two minutes. After the incubation period has ended, place the plate on a magnetic stand until the supernatant is clear. Finally, use a multi-channel pipette to transfer 50 microliters of the clear supernatant from the cleanup tray to a fresh hard-shell plate.First follow library normalization reagents and transfer 20 microliters of the clear supernatant from the hard-shell plate to a new deep-well plate. Add 45 microliters of a magnetic bead suspension to each well of the deep-well plate and use a plate sealer to seal the plate. Next, agitate the plate on a microplate shaker at 1, 800 RPM for 30 minutes.Place the plate on a magnetic stand for two minutes until the supernatant has cleared. Use a pipette to remove the supernatant and dispose of the supernatant into an appropriate hazardous waste container. Then remove the plate from the magnetic stand and use 45 microliters of wash buffer to wash the beads.Agitate the plate on a microplate shaker and place the plate on a magnetic stand for two minutes. After the supernatant clears, discard the supernatant and remove the plate from the magnetic stand. Repeat the washing process with wash buffer once more.Before removing the plate from the magnetic stand, add NaOH to each well. Then agitate the plate on a microplate shaker at 1, 800 RPM for five minutes before placing the plate on a magnetic stand until the liquid is clear. Add 30 microliters of elution buffer to each well of a new 96-well hard-shell thin-wall plate.Finally, transfer 30 microliters of supernatant from the normalization plate to each of the wells containing elution buffer. Now, the final normalized library plate is ready to be sequenced in further experiments. 13 C.glabrata isolates obtained before and after antifungal therapy comprised of C.glabrata ATCC 90030 and twelve isolates from a clinical laboratory were studied.The minimum inhibitory concentration, or MIC, was obtained for each isolate for nine antifungal agents. This table lists the MIC values for each isolate antifungal test condition. The presence of SNPs in genes conferring resistance in isolate correlated with elevated in-vitro MIC against antifungal drugs.This table summarizes the SNP positions in the clinical C.glabrata isolates and the drugs that the genes confer resistance to. After watching this video, viewers can replicate this technique in a diagnostic laboratory setting for accreditation in whole genome sequencing. It highlights the important steps in DNA library preparation and the essential quality control points for accurate and reproducible results.

whole-genome-sequencing-candida-glabrata-for-detection-markers

Research

JoVE Journal

Medicine

Cerenkov Luminescence Imaging (CLI) for Cancer Therapy Monitoring

In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities1-3. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues.
 Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI)4-6. CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium7,8. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one 18F decay was estimated to produce an average of 3 photons in water5. 
 Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others4,5,9,10,11. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET.
 Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study12. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor13,14. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.

Cerenkov Luminescence Imaging CLI for Cancer Therapy Monitoring

Use of Cerenkov Luminescence Imaging (CLI) for monitoring preclinical cancer treatment is described here. This method takes advantage of Cerenkov Radiation (CR) and optical imaging (OI) to visualize radiolabeled probes and thus provides an alternative to PET in preclinical therapeutic monitoring and drug screening.

In  molecular imaging, positron emission tomography (PET) and optical imaging (OI)  are two of the most important and thus most widely used modalities1-3. ...

Identification of Sleeping Beauty Transposon Insertions in Solid Tumors using Linker-mediated PCR

Genomic, proteomic, transcriptomic, and epigenomic analyses of human tumors indicate that there are thousands of anomalies within each cancer genome compared to matched normal tissue. Based on these analyses it is evident that there are many undiscovered genetic drivers of cancer1. Unfortunately these drivers are hidden within a much larger number of passenger anomalies in the genome that do not directly contribute to tumor formation. Another aspect of the cancer genome is that there is considerable genetic heterogeneity within similar tumor types. Each tumor can harbor different mutations that provide a selective advantage for tumor formation2. Performing an unbiased forward genetic screen in mice provides the tools to generate tumors and analyze their genetic composition, while reducing the background of passenger mutations. The Sleeping Beauty (SB) transposon system is one such method3. The SB system utilizes mobile vectors (transposons) that can be inserted throughout the genome by the transposase enzyme. Mutations are limited to a specific cell type through the use of a conditional transposase allele that is activated by Cre Recombinase. Many mouse lines exist that express Cre Recombinase in specific tissues. By crossing one of these lines to the conditional transposase allele (e.g. Lox-stop-Lox-SB11), the SB system is activated only in cells that express Cre Recombinase. The Cre Recombinase will excise a stop cassette that blocks expression of the transposase allele, thereby activating transposon mutagenesis within the designated cell type. An SB screen is initiated by breeding three strains of transgenic mice so that the experimental mice carry a conditional transposase allele, a concatamer of transposons, and a tissue-specific Cre Recombinase allele. These mice are allowed to age until tumors form and they become moribund. The mice are then necropsied and genomic DNA is isolated from the tumors. Next, the genomic DNA is subjected to linker-mediated-PCR (LM-PCR) that results in amplification of genomic loci containing an SB transposon. LM-PCR performed on a single tumor will result in hundreds of distinct amplicons representing the hundreds of genomic loci containing transposon insertions in a single tumor4. The transposon insertions in all tumors are analyzed and common insertion sites (CISs) are identified using an appropriate statistical method5. Genes within the CIS are highly likely to be oncogenes or tumor suppressor genes, and are considered candidate cancer genes. The advantages of using the SB system to identify candidate cancer genes are: 1) the transposon can easily be located in the genome because its sequence is known, 2) transposition can be directed to almost any cell type and 3) the transposon is capable of introducing both gain- and loss-of-function mutations6. The following protocol describes how to devise and execute a forward genetic screen using the SB transposon system to identify candidate cancer genes (Figure 1).

Identification of Sleeping Beauty Transposon Insertions in Solid Tumors using Linker-mediated PCR

A method of identifying unknown drivers of carcinogenesis using an unbiased approach is described. The method uses the Sleeping Beauty transposon as a random mutagen directed to specific tissues. Genomic mapping of transposon insertions that drive tumor formation identifies novel oncogenes and tumor suppressor genes

Genomic, proteomic, transcriptomic, and epigenomic analyses of human tumors indicate that there are thousands of anomalies within each cancer genome ...

An Orthotopic Murine Model of Human Prostate Cancer Metastasis

Our laboratory has developed a novel orthotopic implantation model of human prostate cancer (PCa). As PCa death is not due to the primary tumor, but rather the formation of distinct metastasis, the ability to effectively model this progression pre-clinically is of high value. In this model, cells are directly implanted into the ventral lobe of the prostate in Balb/c athymic mice, and allowed to progress for 4-6 weeks. At experiment termination, several distinct endpoints can be measured, such as size and molecular characterization of the primary tumor, the presence and quantification of circulating tumor cells in the blood and bone marrow, and formation of metastasis to the lung. In addition to a variety of endpoints, this model provides a picture of a cells ability to invade and escape the primary organ, enter and survive in the circulatory system, and implant and grow in a secondary site. This model has been used effectively to measure metastatic response to both changes in protein expression as well as to response to small molecule therapeutics, in a short turnaround time.

This orthotopic model of human prostate cancer allows for quantification of tumor size, circulating tumor cells, and formation of distinct metastasis to the lung. As cells must escape the primary organ, enter the blood stream, and implant into a secondary site, this model effectively recapitulates the scenario in humans.

Our laboratory has developed a novel orthotopic implantation model of  human prostate cancer (PCa). As PCa death is not due to the primary tumor, but  ...

An Affordable HIV-1 Drug Resistance Monitoring Method for Resource Limited Settings

HIV-1 drug resistance has the potential to seriously compromise the effectiveness and impact of antiretroviral therapy (ART). As ART programs in sub-Saharan Africa continue to expand, individuals on ART should be closely monitored for the emergence of drug resistance. Surveillance of transmitted drug resistance to track transmission of viral strains already resistant to ART is also critical. Unfortunately, drug resistance testing is still not readily accessible in resource limited settings, because genotyping is expensive and requires sophisticated laboratory and data management infrastructure. An open access genotypic drug resistance monitoring method to manage individuals and assess transmitted drug resistance is described. The method uses free open source software for the interpretation of drug resistance patterns and the generation of individual patient reports. The genotyping protocol has an amplification rate of greater than 95% for plasma samples with a viral load &#62;1,000 HIV-1 RNA copies/ml. The sensitivity decreases significantly for viral loads &#60;1,000 HIV-1 RNA copies/ml. The method described here was validated against a method of HIV-1 drug resistance testing approved by the United States Food and Drug Administration (FDA), the Viroseq genotyping method. Limitations of the method described here include the fact that it is not automated and that it also failed to amplify the circulating recombinant form CRF02_AG from a validation panel of samples, although it amplified subtypes A and B from the same panel.

Drug resistance testing for HIV-1 infected individuals failing antiretroviral therapy (ART) can guide future therapies and improve treatment outcomes. Optimizing individual and population health outcomes in high HIV prevalence but resource-limited settings will ultimately require affordable and accessible drug resistance genotyping and interpretation methods.

HIV-1 drug resistance has the potential to seriously compromise the effectiveness and impact of antiretroviral therapy (ART). As ART programs in ...

Collection and Extraction of Saliva DNA for Next Generation Sequencing

The preferred source of DNA in human genetics research is blood, or cell lines derived from blood, as these sources yield large quantities of high quality DNA. However, DNA extraction from saliva can yield high quality DNA with little to no degradation/fragmentation that is suitable for a variety of DNA assays without the expense of a phlebotomist and can even be acquired through the mail. However, at present, no saliva DNA collection/extraction protocols for next generation sequencing have been presented in the literature. This protocol optimizes parameters of saliva collection/storage and DNA extraction to be of sufficient quality and quantity for DNA assays with the highest standards, including microarray genotyping and next generation sequencing.

DNA extraction from saliva can provide a readily available source of high molecular weight DNA, with little to no degradation/fragmentation. This protocol provides optimized parameters for saliva collection/storage and DNA extraction to be of sufficient quality and quantity for downstream DNA assays with high quality requirements.

The preferred source of DNA in human genetics research is blood, or cell lines derived from blood, as these sources yield large quantities of high quality ...

Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats

The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also underscores the importance of ethical issues associated with animal use in research.

Early stage hemodynamic dysfunction is critical to the development of kidney disease. Yet, detection methodologies are limited. Recent advances in sonography provide a noninvasive, accurate option for early detection of kidney injury. This study outlines a step-by-step, sonographic methodology for detecting kidney dysfunction using a drug-induced nephrotoxicity rat model.

The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is ...

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Although targeted therapies are initially effective, resistance inevitably emerges. Several methods, such as genetic analysis of resistant clinical specimens, have been applied to uncover these resistance mechanisms to facilitate follow-up care. Although these approaches have led to clinically relevant discoveries, difficulties in attaining the relevant patient material or in deconvoluting the genomic data collected from these specimens have severely hampered the path towards a cure. To this end, we here describe a tool for expeditious discovery that may guide improvement in first-line therapies and alternative clinical management strategies. By coupling preclinical in vitro or in vivo drug selection with next-generation sequencing, it is possible to identify genomic structural variations and/or gene expression alterations that may serve as functional drivers of resistance. This approach facilitates the spontaneous emergence of alterations, enhancing the probability that these mechanisms may be observed in the patients. In this protocol we provide guidelines to maximize the potential for uncovering single nucleotide variants that drive resistance using adherent lines.

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Drug resistance to targeted therapeutics is widespread and the need to identify mechanisms of resistance--prior to or following clinical onset--is critical for guiding alternative clinical management strategies. Here, we present a protocol to couple derivation of drug-resistant lines in vitro with sequencing to expedite discovery of these mechanisms.

Although targeted therapies are initially effective, resistance inevitably emerges. Several methods, such as genetic analysis of resistant clinical ...

A Cell Culture Model of Resistance Arteries

The myoendothelial junction (MEJ), a unique signaling microdomain in small diameter resistance arteries, exhibits localization of specific proteins and signaling processes that can control vascular tone and blood pressure. As it is a projection from either the endothelial or smooth muscle cell, and due to its small size (on average, an area of ~1 &#181;m2), the MEJ is difficult to study in isolation. However, we have developed a cell culture model called the vascular cell co-culture (VCCC) that allows for in vitro MEJ formation, endothelial cell polarization, and dissection of signaling proteins and processes in the vascular wall of resistance arteries. The VCCC has a multitude of applications and can be adapted to suit different cell types. The model consists of two cell types grown on opposite sides of a filter with 0.4 &#181;m pores in which the in vitro MEJs can form. Here we describe how to create the VCCC via plating of cells and isolation of endothelial, MEJ, and smooth muscle fractions, which can then be used for protein isolation or activity assays. The filter with intact cell layers can be fixed, embedded, and sectioned for immunofluorescent analysis. Importantly, many of the discoveries from this model have been confirmed using intact resistance arteries, underscoring its physiological relevance.

A cell culture model of resistance arteries is described, allowing for the dissection of signaling pathways in endothelium, smooth muscle, or between endothelium and smooth muscle (the myoendothelial junction). The selective application of agonists or protein isolation, electron microscopy, or immunofluorescence can be utilized using this cell culture model.

The myoendothelial junction (MEJ), a unique signaling microdomain in small diameter resistance arteries, exhibits localization of specific proteins and ...

Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients

Lipopolysaccharide, also known as endotoxin, is a fundamental component of gram-negative bacteria and plays a crucial role in the development of sepsis and septic shock. The early identification of an infectious process that is rapidly evolving to a critical illness might prompt a quicker and more intensive treatment, thereby potentially leading to better patient outcomes. The Endotoxin Activity (EA) assay can be used at the bedside as a reliable biomarker of systemic endotoxemia. The detection of elevated endotoxin activity levels has been repeatedly shown to be associated with an increased disease severity in patients with sepsis and septic shock. The assay is quick and easy to perform. Briefly, after sampling, an aliquot of whole blood is mixed with an anti-endotoxin antibody and with added LPS. Endotoxin activity is measured as the relative oxidative burst of primed neutrophils as detected by chemioluminescence. The assay&#39;s output is expressed on a scale from 0 (absent) to 1 (maximal) and categorized as &#8220;low&#8221; (&#60;0.4 units), &#8220;intermediate&#8221; (0.4&#8211;0.59 units), or &#8220;high&#8221; (&#8805;0.6 units). The detailed methodology and rationale for the implementation of the EA assay are reported in this manuscript.

We hereby present a protocol to measure at the bedside the endotoxin activity of human whole blood samples. The Endotoxin Activity assay is a simple test to perform and may be a useful biomarker in critically ill patients with sepsis.

Lipopolysaccharide, also known as endotoxin, is a fundamental component of gram-negative bacteria and plays a crucial role in the development of sepsis ...

Repetitive Blood Sampling from the Subclavian Vein of Conscious Rat

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to detect drug exposure. The rat blood sampling method determines the quality of the plasma and further affects the precision of the test results. The subclavian vein blood collection method described in this protocol collects blood samples repeatedly in the conscious state of animals to meet the needs of PK and TK tests. The skills of restraint handling and appropriate procedure of needle incision ensure the success rate of blood collection. It is easy to operate while ensuring the quality of plasma and at the same time catering to animal welfare. However, this method requires skilled operation, and an improper one may cause animal weakness, pain, lameness, and even mortality. The current method has been used in the testing facility for a 4-week oral toxicity study in Sprague Dawley (SD) rats with TK. The maximum amount of blood collected within 24 h did not exceed 20% of the animal's total blood. The animals' body weight was more than 200 g for males and females. The data showed that the animals' bodyweight increased steadily every week, and the clinical observation was normal after repetitive sample collection.

The present protocol describes a simple and efficient method for collecting blood from the subclavian vein in rats. It enables rapid, timely, and easily identifiable sampling without anesthesia and obtains high-quality blood through repetitive sample collection.

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to ...