Aspectos farmacocinéticos y farmacodinámicos para la lectura interpretada del antibiograma / Pharmacokinetic and pharmacodynamic aspects of interpretive reading of the antibiogram

La lectura interpretada del antibiograma se basa fundamentalmente en datos microbiológicos y farmacodinámicos. La información microbiológica separa las cepas bacterianas en aquellas que no tienen mecanismos de resistencia a los antibióticos y las que sí los tienen. Con esta información y al tratar los parámetros farmacocinéticos de cada antimicrobiano es posible realizar aproximaciones farmacodinámicas que puedan predecir el éxito o el fracaso del antibiótico en una determinada infección. Numerosos estudios realizados han permitido seleccionar 3 índices farmacodinámicos que se asocian al éxito terapéutico de los antibióticos: tasa de concentración máxima/concentración mínima inhibitoria (CMI), tasa de área bajo la curva/CMI y tiempo en que las concentraciones superan la CMI del patógeno. La simulación de Monte Carlo permite calcular el punto de corte de sensibilidad para cada antibiótico-microorganismo y buscar una probabilidad superior al 90% para alcanzar el objetivo. Los criterios clínicos deberían confirmar los puntos de corte o, en caso contrario, obligarán a su reconsideración (AU)

The interpretative reading of the antimicrobial susceptibility test is mainly based on microbiological and pharmacodynamic data. Microbiological information splits bacterial strains into those having antimicrobial resistance mechanisms and that do not. With this information, and using the pharmacokinetic parameters of each antimicrobial it is possible to make pharmacodynamic approaches to predict antibiotic success or failure in an infectious process. Many studies have emphasized the usefulness of three pharmacodynamic indexes associated with therapeutic success: rate maximum concentration/MIC (Cmax/MIC), area under de curve /MIC (AUC/MIC) ratio, and time to concentration excess MIC (T>MIC). The Monte Carlo simulation enables the susceptibility breakpoint to be calculated for each antibiotic-microorganism, trying to achieve its target with a probability greater than 90%. Clinical data should confirm the susceptibility breakpoints or, if not, these breakpoints should be to be reconsidered (AU)

[Pharmacokinetic and pharmacodynamic aspects of interpretive reading of the antibiogram]. / Aspectos farmacocinéticos y farmacodinámicos para la lectura interpretada del antibiograma.

The interpretative reading of the antimicrobial susceptibility test is mainly based on microbiological and pharmacodynamic data. Microbiological information splits bacterial strains into those having antimicrobial resistance mechanisms and that do not. With this information, and using the pharmacokinetic parameters of each antimicrobial it is possible to make pharmacodynamic approaches to predict antibiotic success or failure in an infectious process. Many studies have emphasized the usefulness of three pharmacodynamic indexes associated with therapeutic success: rate maximum concentration/MIC (C(max)/MIC), area under de curve /MIC (AUC/MIC) ratio, and time to concentration excess MIC (T>(MIC)). The Monte Carlo simulation enables the susceptibility breakpoint to be calculated for each antibiotic-microorganism, trying to achieve its target with a probability greater than 90%. Clinical data should confirm the susceptibility breakpoints or, if not, these breakpoints should be to be reconsidered.

El genoma del corynebacterium urealyticum ha sido completamente secuenciado: un progreso clave para conocer la uropatogenicidad y "estilo de vida" de este microorganismo / The Corynebacterium urealyticum genome has been completely sequenced: a key advance to know the uropathogenicity and «life style» of this microorganism

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[Risk factors of mortality in invasive pneumococcal disease]. / Factores relacionados con la mortalidad de la enfermedad neumocócica invasiva.

BACKGROUND AND OBJECTIVE: To analyze the risk factors associated with mortality in invasive pneumococcal disease in the university hospital Fundación Jiménez Díaz (Madrid, Spain) during 11 years. PATIENTS AND METHOD: We performed a retrospective study of patients attending the emergency service of the hospital from January 1993 to August 2003. We registered data on mortality, clinical and microbiological evolution and relapses. RESULTS: We studied 263 patients with pneumococcal baceteremia and invasive disease caused by Streptococcus pneumoniae (pneumonia, meningitis, sepsis, bacteremia of unknown origin and oligoarthritis). Mortality was 12.5%. Variables associated with mortality in a logistic regression analysis included absence of leukocytosis (p = 0.04), acidosis (p < 0.01), respiratory signs and symptoms (tachypnea, pleuritic pain) (p = 0.02), and neurologic manifestations (decreased consciousness level; (p < 0.01). CONCLUSION: Patients at highest risk of death because of invasive pneumococcal disease are critically ill, with no leukocytosis, with severe respiratory or neurological symptoms and undergoing invasive procedures such as mechanical ventilation and tracheostomy.