Name: multiplex therapeutic drug monitoring by isotope-dilution hplc-ms/ms of antibiotics in critical illnesses
Uploaded: 2018-08-30T15:00:00
Description: Watch this Scientific Journal Video about Multiplex Therapeutic Drug Monitoring by Isotope-dilution HPLC-MS/MS of Antibiotics in Critical Illnesses at JoVE.com

Los autores agradecen a Dr. Schütze por su ayuda a establecer el método presentado y Dr. Zoller por el valioso aporte con respecto a la gama de calibración apropiada. Los autores reconocen también el personal técnico de las instalaciones de la espectrometría de masas.

Nota: Se recomienda para trabajar en una campana de humos al manipular disolventes orgánicos, como el metanol. Preparar todos los búferes y fases móviles en matraces aforados. Si no indique lo contrario, las soluciones se pueden almacenar a temperatura ambiente hasta 1 mes después de la preparación.
1. preparación de los calibradores y las muestras de Control de calidad
Nota: Una hoja de análisis de datos correspondientes para la preparación de soluciones stoc...

<ol>
	<li>Fleischmann, 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=Assessment+of+Global+Incidence+and+Mortality+of+Hospital-treated+Sepsis.+Current+Estimates+and+Limitations.">Assessment of Global Incidence and Mortality of Hospital-treated Sepsis. Current Estimates and Limitations.</a> American Journal of Respiratory and Critical Care Medicine. 193 (3), 259-272 (2016).</li><li>Dellinger, R. P., 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=Surviving+Sepsis+Campaign:+international+guidelines+for+management+of+severe+sepsis+and+septic+shock,+2012.">Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012.</a> Intensive Care Medicine. 39 (2), 165-228 (2013).</li><li>Lodise, T. P., Drusano, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacokinetics+and+pharmacodynamics:+optimal+antimicrobial+therapy+in+the+intensive+care+unit.">Pharmacokinetics and pharmacodynamics: optimal antimicrobial therapy in the intensive care unit.</a> Critical Care Clinics. 27 (1), 1-18 (2011).</li><li>Macedo, R. S., Onita, J. H., Wille, M. P., Furtado, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacokinetics+and+pharmacodynamics+of+antimicrobial+drugs+in+intensive+care+unit+patients.">Pharmacokinetics and pharmacodynamics of antimicrobial drugs in intensive care unit patients.</a> Shock. 39, 24-28 (2013).</li><li>Petersson, J., Giske, C. G., Eliasson, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standard+dosing+of+piperacillin+and+meropenem+fail+to+achieve+adequate+plasma+concentrations+in+ICU+patients.">Standard dosing of piperacillin and meropenem fail to achieve adequate plasma concentrations in ICU patients.</a> Acta Anaesthesiologica Scandinavica. 60 (10), 1425-1436 (2016).</li><li>Abdul-Aziz, M. H., Lipman, J., Mouton, J. W., Hope, W. W., Roberts, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applying+pharmacokinetic/pharmacodynamic+principles+in+critically+ill+patients:+optimizing+efficacy+and+reducing+resistance+development.">Applying pharmacokinetic/pharmacodynamic principles in critically ill patients: optimizing efficacy and reducing resistance development.</a> Seminars in Respiratory and Critical Care Medicine. 36 (1), 136-153 (2015).</li><li>Imani, S., Buscher, H., Marriott, D., Gentili, S., Sandaradura, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Too+much+of+a+good+thing:+a+retrospective+study+of+beta-lactam+concentration-toxicity+relationships.">Too much of a good thing: a retrospective study of beta-lactam concentration-toxicity relationships.</a> Journal of Antimicrobial Chemotherapy. 72 (10), 2891-2897 (2017).</li><li>Ventola, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+antibiotic+resistance+crisis:+part+1:+causes+and+threats.">The antibiotic resistance crisis: part 1: causes and threats.</a> Pharmacy &amp; Therapeutics. 40 (4), 277-283 (2015).</li><li>Pulcini, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibiotic+stewardship:+update+and+perspectives.">Antibiotic stewardship: update and perspectives.</a> Clinical Microbiology and Infection. 23 (11), 791-792 (2017).</li><li>Cairns, K. 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=The+impact+of+a+multidisciplinary+antimicrobial+stewardship+team+on+the+timeliness+of+antimicrobial+therapy+in+patients+with+positive+blood+cultures:+a+randomized+controlled+trial.">The impact of a multidisciplinary antimicrobial stewardship team on the timeliness of antimicrobial therapy in patients with positive blood cultures: a randomized controlled trial.</a> Journal of Antimicrobial Chemotherapy. 71 (11), 3276-3283 (2016).</li><li>Baur, 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=Effect+of+antibiotic+stewardship+on+the+incidence+of+infection+and+colonisation+with+antibiotic-resistant+bacteria+and+Clostridium+difficile+infection:+a+systematic+review+and+meta-analysis.">Effect of antibiotic stewardship on the incidence of infection and colonisation with antibiotic-resistant bacteria and Clostridium difficile infection: a systematic review and meta-analysis.</a> Lancet Infectious Diseases. 17 (9), 990-1001 (2017).</li><li>Roberts, J. A., Norris, R., Paterson, D. L., Martin, 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=Therapeutic+drug+monitoring+of+antimicrobials.">Therapeutic drug monitoring of antimicrobials.</a> British Journal of Clinical Pharmacology. 73 (1), 27-36 (2012).</li><li>Paal, M., Zoller, M., Schuster, C., Vogeser, M., Schutze, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+quantification+of+cefepime,+meropenem,+ciprofloxacin,+moxifloxacin,+linezolid+and+piperacillin+in+human+serum+using+an+isotope-dilution+HPLC-MS/MS+method.">Simultaneous quantification of cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid and piperacillin in human serum using an isotope-dilution HPLC-MS/MS method.</a> Journal of Pharmaceutical and Biomedical Analysis. 152, 102-110 (2018).</li><li>Vogeser, M., Seger, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pitfalls+associated+with+the+use+of+liquid+chromatography-tandem+mass+spectrometry+in+the+clinical+laboratory.">Pitfalls associated with the use of liquid chromatography-tandem mass spectrometry in the clinical laboratory.</a> Clinical Chemistry. 56 (8), 1234-1244 (2010).</li><li>United States Pharmacopeia and National Formulary. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+&#60;621&#62;.">Chapter &#60;621&#62;.</a> CHROMATOGRAPHY (USP 37-NF 32 S1). , 6376-6385 (2014).</li><li>Wong, G., Sime, F. B., Lipman, J., Roberts, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+do+we+use+therapeutic+drug+monitoring+to+improve+outcomes+from+severe+infections+in+critically+ill+patients?.">How do we use therapeutic drug monitoring to improve outcomes from severe infections in critically ill patients?.</a> BMC Infectious Diseases. 14, 288 (2014).</li><li>. Cefepime hydrochloride: Highlights of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2016/050679s040lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2016/050679s040lbl.pdf</a> (2016)</li><li>. Meropenem: Highlights of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2008/050706s022lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2008/050706s022lbl.pdf</a> (2006)</li><li>. Ciprofloxacin hydrochloride: Highlights of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2016/019537s086lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2016/019537s086lbl.pdf</a> (2016)</li><li>. Moxifloxacin hydrochloride: Highlights of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2010/021277s038lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2010/021277s038lbl.pdf</a> (2010)</li><li>. Linezolid: Highlights of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2012/021130s028lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2012/021130s028lbl.pdf</a> (2011)</li><li>. Piperacillin and Tazobactam: Highlighs of prescribing information Available from: <a target="_blank" href="https://www.accessdata.fda.gov/drugsatfda_docs/Label/2017/050684s88s89s90_050750s37s38s39lbl.pdf">https://www.accessdata.fda.gov/drugsatfda_docs/Label/2017/050684s88s89s90_050750s37s38s39lbl.pdf</a> (2017)</li><li>Zander, 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=Effects+of+biobanking+conditions+on+six+antibiotic+substances+in+human+serum+assessed+by+a+novel+evaluation+protocol.">Effects of biobanking conditions on six antibiotic substances in human serum assessed by a novel evaluation protocol.</a> Clinical Chemistry and Laboratory. 54 (2), 265-274 (2016).</li><li>Zander, 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=Quantification+of+piperacillin,+tazobactam,+cefepime,+meropenem,+ciprofloxacin+and+linezolid+in+serum+using+an+isotope+dilution+UHPLC-MS/MS+method+with+semi-automated+sample+preparation.">Quantification of piperacillin, tazobactam, cefepime, meropenem, ciprofloxacin and linezolid in serum using an isotope dilution UHPLC-MS/MS method with semi-automated sample preparation.</a> Clinical Chemistry and Laboratory. 53 (5), 781-791 (2015).</li></ol>

En este manuscrito, se presenta el protocolo para un método de masa basado en la espectrometría de tándem sencillo y robusto para la cuantificación de los antibióticos utilizados en el ICU19, es decir, cefepime, meropenem, ciprofloxacina, moxifloxacina, linezolid, y piperacilina14. Una hoja de cálculo acompaña el manuscrito para la preparación de soluciones stock de antibióticos, calibradores y controles de calidad, teniendo en cuenta la pureza de los antibióticos...

Aunque los antibióticos han revolucionado la práctica de la medicina, graves infecciones bacterianas siguen siendo una causa importante de morbilidad y mortalidad en enfermedades graves1. En este sentido, la administración pronta de un antiinfeccioso adecuado en una dosis adecuada es de importancia superior para el control de la enfermedad2.
Un creciente cuerpo de evidencia demuestra que el tratamiento empírico con antibióticos de amplio espectro se está convirtiendo en cada vez más problemático con la complejidad de las poblaciones de pacientes. Esto es especialmente cierto para unidades de cuidados intensivos (UCI), donde una enorme variabilidad interindividual de los parámetros farmacocinéticos claves del (PK) con frecuencia se observa3,4. En consecuencia, pacientes de la UCI están en riesgo inminente de niveles sub-terapéuticos con el peligro de un escaso éxito terapéutico5,6. Por otra parte, pacientes exponen innecesariamente a excesivamente altas concentraciones de antibióticos que pueden resultar en eventos adversos graves con ningún beneficios clínicos7. El mal uso de antibióticos y la dosificación insuficiente también han impulsado la difusión de la resistencia a los antibióticos, que se está convirtiendo en una amenaza creciente para la salud pública8.
Para mejorar el uso de antibióticos y para preservar su effectivenessas tiempo como sea posible, la Organización Mundial de la salud ha puesto en marcha un plan de acción global sobre resistencia a los antimicrobianos en 20159. Los programas de administración de antibióticos constituyen una piedra angular esencial de uso prudente de antimicrobiano en la salud pública nacional estrategias10, ayudando a los médicos a mejorar significativamente la calidad de atención del paciente11 y, al mismo tiempo, la reducción de la resistencia a los antibióticos12. Antimicrobiano dosis en pacientes individuales a través de la aplicación de drogas terapéuticas (TDM) el monitoreo es un instrumento clave en este contexto13.
Hasta la fecha, disponible en el mercado TDM ensayos sólo están disponibles para los antibióticos glucopéptidos y aminoglucósidos. La cuantificación de sustancias de otras clases comúnmente requiere un desarrollo interno o validación que puede resultar engorroso. Por lo tanto, presentamos en detalle el protocolo para un ensayo basada en espectrometría de masa sólido que puede ser utilizado para la cuantificación de los principales antibióticos en UCI dentro de sus rangos de concentración relevante clínica14. El método fue establecido recientemente en nuestro centro de espectrometría de masas y se ha aplicado para la rutina de TDM en UCI desde entonces. El procedimiento utiliza un marco analítico sencillo y simple con una limpieza uniforme de la muestra, lo que permite la rápida aplicación de antibiótico TDM en muchas instalaciones con capacidades de espectrometría de masas.
El protocolo descrito aquí fue optimizado para la cuantificación de cefepime, meropenem, ciprofloxacina, moxifloxacina, linezolid y piperacilina en suero humano, usando la cromatografía de líquidos de dilución isotópica (LC) en combinación con un tándem masa Espectrometría (MS/MS). Para la dilución del isótopo metodología LC-MS/MS, compuestos marcados con isótopos estables se añaden a una muestra de interés con una matriz específica (p. ej., suero). Normas de marcado con el isótopo pueden distinguirse de sus contrapartes sin etiqueta, es decir el analito de interés, debido a distintos pesos moleculares de la molécula natural y sus productos de fragmentación, como una transición de padres-ion a hija-ion. Compuestos marcados con isótopos tienen un comportamiento general fisicoquímico idéntico en comparación con su contraparte sin etiqueta, son normas internas ideal para MS/MS, lo que permite una cuantificación del analito casi independiente de la matriz con un alto grado de precisión15. Hoy en día, muchos estables isótopo-etiquetada estándares internos que pueden utilizarse para la cuantificación de moléculas pequeñas, como el TDM de antimicrobianos, están disponibles en el mercado.
La separación cromatográfica de los analitos antibióticos en el protocolo descrito se realiza con una columna de fase inversa de longitud de la cadena alquil C8 analítica (100 mm x 2,1 mm, 3 μm tamaño de las partículas). Durante el desarrollo del método, los factores internos estándar matriz normalizada para todos los analitos fue entre 94,6% y 105,4%, con un coeficiente de variación de ≤8.3%14.

<table>
	<tbody>
		<tr>
			<td>cefepime hydrochloride</td>
			<td>Sigma-Aldrich</td>
			<td>1097636</td>
			<td>USP Reference Standard</td>
		</tr>
		<tr>
			<td>meropenem trihydrate</td>
			<td>Sigma-Aldrich</td>
			<td>Y0001252</td>
			<td>EP Reference Standard</td>
		</tr>
		<tr>
			<td>ciprofloxacin</td>
			<td>Sigma-Aldrich</td>
			<td>17850</td>
			<td></td>
		</tr>
		<tr>
			<td>moxifloxacin hydrochloride</td>
			<td>Sigma-Aldrich</td>
			<td>SML1581</td>
			<td></td>
		</tr>
		<tr>
			<td>linezolid</td>
			<td>Toronto Research Chemicals</td>
			<td>L466500</td>
			<td></td>
		</tr>
		<tr>
			<td>piperacillin sodium salt</td>
			<td>Sigma-Aldrich</td>
			<td>93129</td>
			<td></td>
		</tr>
		<tr>
			<td>cefepime-13C12D3 sulfate</td>
			<td>Alsachim</td>
			<td>C1297</td>
			<td>Isotope labelled internal standard for cefepime</td>
		</tr>
		<tr>
			<td>meropenem-D6</td>
			<td>Toronto Research Chemicals</td>
			<td>M225617</td>
			<td>Isotope labelled internal standard for meropenem</td>
		</tr>
		<tr>
			<td>ciprofloxacin-D8</td>
			<td>Toronto Research Chemicals</td>
			<td>C482501</td>
			<td>Isotope labelled internal standard for ciprofloxacin</td>
		</tr>
		<tr>
			<td>moxifloxacin-13C1D3 hydrochloride</td>
			<td>Toronto Research Chemicals</td>
			<td>M745003</td>
			<td>Isotope labelled internal standard for moxifloxacin</td>
		</tr>
		<tr>
			<td>linezolid-D3</td>
			<td>Toronto Research Chemicals</td>
			<td>L466502</td>
			<td>Isotope labelled internal standard for linezolid</td>
		</tr>
		<tr>
			<td>piperacillin-D5</td>
			<td>Toronto Research Chemicals</td>
			<td>P479952</td>
			<td>Isotope labelled internal standard for piperacillin</td>
		</tr>
		<tr>
			<td>methanol</td>
			<td>JT Baker</td>
			<td>8402</td>
			<td></td>
		</tr>
		<tr>
			<td>HPLC grade water</td>
			<td>JT Baker</td>
			<td>4218</td>
			<td></td>
		</tr>
		<tr>
			<td>formic acid</td>
			<td>Biosolve</td>
			<td>6914132</td>
			<td></td>
		</tr>
		<tr>
			<td>acetic acid</td>
			<td>Biosolve</td>
			<td>1070501</td>
			<td></td>
		</tr>
		<tr>
			<td>ammonium formate</td>
			<td>Sigma-Aldrich</td>
			<td>70221-25G-F</td>
			<td></td>
		</tr>
		<tr>
			<td>tert-Butyl methyl ether</td>
			<td>Merck</td>
			<td>101845</td>
			<td></td>
		</tr>
		<tr>
			<td>Fortis 3 &#956;m C8 100 * 2.1 mm</td>
			<td>Fortis</td>
			<td>F08-020503</td>
			<td></td>
		</tr>
		<tr>
			<td>Ti-PEEK-encased Prifilter (2 &#956;m)</td>
			<td>Chromsystems</td>
			<td>15011</td>
			<td></td>
		</tr>
		<tr>
			<td>2795 Alliance HPLC system</td>
			<td>Waters</td>
			<td>176000491</td>
			<td></td>
		</tr>
		<tr>
			<td>Quattro micro API Tandem Quadrupole System</td>
			<td>Waters</td>
			<td>720000338</td>
			<td></td>
		</tr>
		<tr>
			<td>QuanLynx 4.1 software</td>
			<td>Waters</td>
			<td>/</td>
			<td>Data evaluation software provided by the mass spectrometer manufacturer</td>
		</tr>
	</tbody>
</table>

multiplex therapeutic drug monitoring by isotope-dilution hplc-ms/ms of antibiotics in critical illnesses

Hay una demanda creciente para el monitoreo de drogas terapéuticas de antibióticos en muchas instalaciones clínicas, particularmente con respecto a la implementación de programas de administración de antibióticos del hospital.
En el presente trabajo, presentamos un protocolo multiplex alto rendimiento líquido cromatografía-espectrometría total en tándem (HPLC-MS/MS) para la cuantificación de cefepime, meropenem, ciprofloxacina, moxifloxacina, linezolid y piperacilina, utilizados antibióticos en unidades de cuidados intensivos. El método comprensivo anteriormente se validó según la pauta de la Agencia Europea de medicamentos.
Después de una limpieza rápida de la muestra, los analitos son separados en una columna HPLC de fase reversa C8 dentro de 4 minutos y cuantificados con el correspondientes estables isótopo-etiquetada estándares internos en espectrometría de masas por electrospray ionización (ESI +) en reacción de múltiples tiempo control (MRM). El método presentado utiliza una instrumentación simple ajuste con condiciones cromatográficas uniforme, lo que permite el seguimiento diario y robusto antibiótico terapéutico en los laboratorios clínicos. La curva de calibración extiende el rango de concentración farmacocinética, así como antibióticos cantidades cerca de la concentración inhibitoria mínima (CIM) de las bacterias susceptibles y las concentraciones máximas (Cmax) que se obtienen con bolo regímenes de administración. Sin la necesidad de la dilución de suero antes de la limpieza de la muestra, puede obtenerse el área bajo la curva para un antibiótico administrado a través de mediciones múltiples.

Utilizando el protocolo descrito, un cromatograma típico se muestra en la figura 2. Según el United States Pharmacopeia (USP) cromatografía directrices16, se determinó el volumen muerto de la columna en el sistema actual con ~0.22 mL y el volumen de la columna extra (incluyendo los conectores, inyector y tubería) con ~0.08 mL, dando un volumen de retención de ~0.30 mL. Los factores de retención calculado para todos los analitos ...

Watch this Scientific Journal Video about Multiplex Therapeutic Drug Monitoring by Isotope-dilution HPLC-MS/MS of Antibiotics in Critical Illnesses at JoVE.com

Multiplex Therapeutic Drug Monitoring by Isotope-dilution HPLC-MS/MS of Antibiotics in Critical Illnesses

Múltiplex análisis farmacológico por la dilusión del isótopo HPLC-MS/MS de los antibióticos en enfermedades graves

Aquí presentamos un protocolo de masa basado en la espectrometría de tándem para la cuantificación de los antibióticos utilizados en unidades de cuidados intensivos, es decir, cefepime, meropenem, ciprofloxacina, moxifloxacina, linezolid y piperacilina.

There is an ever-increasing demand for the therapeutic drug monitoring of antibiotics in many clinical facilities, particularly with regard to the ...

Therapeutic drug monitoring of antibiotics is increasingly recognized as an important element for the implementation of national and local antibiotic stewardship programs. To meet this increasing demand of antibiotic therapeutic drug monitoring in medical facilities, we present a protocol for the quantification of antibiotics in circulation that aims to adjust the dosage to the susceptibility of the involved pathogens. The presented mass spectrometry-based protocol was optimized for the quantification of the most commonly used antibiotics in intensive care units, namely cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid, and piperacillin.Due to the broad calibration range, the method can also be used to calculate the pharmacokinetic area under the curve for an administered antibiotic. With a total turnaround time of approximately 30 minutes, the presented protocol is suitable for daily antibiotic therapeutic drug monitoring in clinical laboratories. First spike nine volumes of drug-free serum with one volume of previously prepared 10-fold concentrated spike solutions to obtain the serum calibrators zero through seven and quality controls A through D.For example, add 0.5 milliliters of spike solution to 4.5 milliliters of serum in a 10-milliliter polypropylene tube and incubate it for 15 minutes at four degrees Celsius on a roller mixer at 50 rpm.Use a repetitive pipette to generate 100-microliter aliquots of the calibrators and quality controls in 1.5-milliliter polypropylene tubes. Store the calibrators, quality controls, and previously prepared antibiotic stock solutions at minus 80 degrees Celsius for up to six months. After preparing six internal standard stock solutions, combine them in a 1.5-milliliter polypropylene tube to yield a five-fold concentrated internal standard mix.Add the desired internal standards to 965 microliters of 25%methanol in water. Store the internal standard stock solutions and the five-fold concentrated internal standard mix at minus 80 degrees Celsius. To prepare mobile phase A, add approximately 500 milliliters of HPLC grade water to a 1, 000-milliliter volumetric flask.Add one milliliter of formic acid, 10 milliliters of one-molar ammonium formate, and fill the flask to 1, 000 milliliters with HPLC grade water. Then transfer the mobile phase solution to a clean glass bottle. To prepare mobile phase B, add HPLC grade absolute methanol to a clean glass bottle.To prepare the purge solvent, add approximately 500 milliliters of distilled water to a 1, 000-milliliter volumetric flask. Add 70 milliliters of absolute methanol, one milliliter of formic acid, and fill the flask to 1, 000 milliliters with distilled water. Transfer the solvent to a clean glass bottle.Connect the bottles with mobile phases A and B and the purge solvent to the HPLC system. Make sure that the needle wash solvent tube is connected to the bottle containing mobile phase B.To prepare the precipitation agent, add 2.5 milliliters of methyl tert-butyl ether to a 25-milliliter volumetric flask and fill to 25 milliliters with absolute methanol. Place a C8 reversed phase column into the column chamber, then connect the column to the HPLC and mass spectrometer in the direction of the flow.In order to generate the sample list, open the corresponding sample measurement master file template and add the patient samples to be processed. Generate groups of up to 20 patient samples and flank them with the corresponding quality control pair. Using the Inlet file control software, set the Wet Prime function to 50%mobile phase A and 50%mobile phase B and wet prime for two minutes with a flow rate of one milliliter per minute.Next, refresh the syringe by executing six strokes of 600 microliters in the control software. To equilibrate the C8 reversed phase column, turn on the the flow in the inlet file and flush it with 7%mobile phase B and 93%mobile phase A for a minimum of five minutes, using a flow rate of 0.4 or 0.5 milliliters per minute. Visually verify the column temperature of 30 degrees Celsius.With a repetitive pipette, add 25 microliters of the internal standard mix to the thawed calibrator, QC sample, or patient serum in a 1.5-milliliter polypropylene tube and vortex the tube for a few seconds. Then incubate the mixture for five minutes at room temperature on a benchtop shaker. After incubation, add 150 microliters of the precipitation reagent to the sample internal standard mix with a repetitive pipette.Vortex the tube for a few seconds and then incubate for five minutes at room temperature on a benchtop shaker. Following this, centrifuge the suspension at 20, 000 times gravity in a tabletop centrifuge for 10 minutes at four degrees Celsius. Dilute the supernatant one in three with HPLC grade water in a glass vial with a micro insert.Then, place the sample in the HPLC autosampler. Manually start the HPLC-MS/MS analysis in the sample measurement control file. To process the samples, open the corresponding sample measurement control file, select the calibrators, quality controls, and patient samples and evaluate them with the antibiotics quantification method.Check whether the peaks for a specific analyte are properly integrated. Inspect the peaks for each calibrator, QC, and patient sample and manually reintegrate them at the baseline if necessary. Study the calibration curve and examine whether it fulfills linearity over the entire calibration range, a calibration coefficient greater than 0.99, a deviation of each calibration standard within plus or minus 15%of the nominal value except for the lower limit of quantification where a plus or minus 20%is required.Reject a calibration standard not complying with the above-mentioned criteria and reevaluate the calibration curve, including the regression analysis. Now, study the quality controls and examine whether the deviations are within plus or minus 15%of the nominal value. If the quality controls for a specific batch do not fulfill the quality criteria, the samples must be reinjected or even be reprocessed if significant deviations persist.Measured concentrations of a batch must also be evaluated whether they are plausible or not. If the concentration of a patient's sample exceeds the concentration of the highest calibrator, dilute the sample with distilled water up to one in five before the sample cleanup. Repeat the previous cleanup steps for that specific sample and reprocess it.The calculated retention factors for all analytes were 2.8 to 4.2. A sample chart list for the processed samples is shown here. The key parameter is the response gradually increasing with the analyte concentration due to the constant amount of added isotope-labeled internal standard.The calibration curve and quality controls for the example shown here fulfill all quality criteria. The coefficient of determination r-squared is greater than 0.995 and the deviation of the calibrators and the QC samples is within plus or minus 15%of the nominal value. The measured parent-to-daughter ion transitions show four peaks at the same retention time.The two upper peaks depict two transitions that are measured for the analyte of interest and the lower two peaks represent the transitions for the corresponding isotope-labeled internal standard. The first patient has a high serum trough level of 83.4 milligrams per liter of piperacillin that is also sufficient for problem pathogens. The second patient has a concentration of approximately 0.2 milligrams per liter, which is below the lowest calibrator.The third patient has low piperacillin trough concentration of only 5.3 milligrams per liter that is not sufficient for the majority of pathogens. The presented protocol is suitable for isotope dilution HPLC-tandem mass spectrometry-based quantification of cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid, and piperacillin in human serum. The method uses a rather simple instrument setup and will be there transferable to various mass spectrometry-based platforms.Chromatographic separation of the analytes of interest can also be obtained with a flow rate of 0.4 milliliters per minute as given in the present video. The described method can be used for pharmacokinetic studies as the calibration range allows both the quantification of concentrations close to the minimal inhibitory concentration of a susceptible pathogen as well as peak concentrations that are obtained with bolus administration regimens. After its development this method has been implemented in a mass spectrometry-based care facility for the antibiotic therapeutic drug monitoring in critically ill patients.Due to the fact that beta-lactam antibiotics are chemically unstable once they are dissolved, the quality of the pre-analytical phase such as sample storage plays a vital role in obtaining reliable quantification results. Don't forget that working with organic solvents is hazardous and precautions such as working in a fume should always be taken while preparing chromatography solvents and the precipitation reagent.

Research

JoVE Journal

Medicine

Bronchial Thermoplasty:  A Novel Therapeutic Approach to Severe Asthma

Bronquial termoplastia: un nuevo enfoque terapéutico para el asma grave

Bronchial thermoplasty is a non-drug procedure for severe persistent asthma that delivers thermal energy to the airway wall in a precisely controlled ...

Investigación

Medicina

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

Un método de monitoreo asequible VIH-1 Resistencia a los medicamentos para los entornos con recursos limitados

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

A Simple Critical-sized Femoral Defect Model in Mice

A-crítico tamaño femoral Defecto sencillo modelo en ratones

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

Use of Ultra-high Field MRI in Small Rodent Models of Polycystic Kidney Disease for In Vivo Phenotyping and Drug Monitoring

Use of Ultra-high Field MRI in Small Rodent Models of Polycystic Kidney Disease for In Vivo Phenotyping and Drug Monitoring

El uso de ultra-alta MRI Field en Modelos pequeño roedor de la enfermedad renal poliquística para<em&gt; En Vivo</em&gt; Fenotipificación de Drogas y Vigilancia

Several in vivo pre-clinical studies in Polycystic Kidney Disease (PKD) utilize orthologous rodent models to identify and study the genetic and molecular ...

Establishment of a Segmental Femoral Critical-size Defect Model in Mice Stabilized by Plate Osteosynthesis

Establecimiento de un defecto segmentario Modelo femoral de tamaño crítico en ratones estabilizado por osteosíntesis Plate

The use of tissue-engineered bone constructs is an appealing strategy to overcome drawbacks of autografts for the treatment of massive bone defects. As a ...

A Detailed Protocol for Physiological Parameters Acquisition and Analysis in Neurosurgical Critical Patients

Un protocolo detallado de parámetros fisiológicos de adquisición y análisis en pacientes críticos neuroquirúrgicos

Intracranial pressure (ICP) monitoring is now widely used in neurosurgical critical patients. Besides mean ICP value, the ICP derived parameters such as ...

Standardized Hemorrhagic Shock Induction Guided by Cerebral Oximetry and Extended Hemodynamic Monitoring in Pigs

Inducción de choque hemorrágico estandarizada guiada por oximetría cerebral y monitoreo hemodinámico extendido en cerdos

Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an ...

Assessing Therapeutic Angiogenesis in a Murine Model of Hindlimb Ischemia

Evaluación de la angiogénesis terapéutica en un modelo murino de isquemia de las extremidades posteriores

Critical limb ischemia (CLI) is a serious condition that entails a high risk of lower limb amputation. Despite revascularization being the gold-standard ...

A Rat Carotid Artery Pressure-Controlled Segmental Balloon Injury with Periadventitial Therapeutic Application

Una lesión de globo segmentario controlada por presión arterial carótida de rata con aplicación terapéutica periavential

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the ...

Validated LC-MS/MS Panel for Quantifying 11 Drug-Resistant TB Medications in Small Hair Samples

Panel LC-MS/MS validado para cuantificar 11 medicamentos resistentes a la tuberculosis en muestras de pelo pequeño

Drug resistant-tuberculosis (DR-TB) is a growing public health threat, and assessment of therapeutic drug levels may have important clinical benefits. ...