Archive for September 3, 2011

Sensibilidad a colistín – evaluación puntos de corte disponibles en el ATBgrama x difusión

Revista Argentina de Microbiología Jul-Sept 2004 V.36 P.125-129


1 Laboratorio de Bacteriología, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín,

2 Carrera de Especialización en Bacteriología Clínica. Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. Av. Córdoba 2351, 1120 Ciudad Autónoma de Buenos Aires, Argentina.

*Correspondencia. E-mail:

Las infecciones producidas por microorganismos multirresistentes son uno de los mayores problemas en los centros asistenciales. Frecuentemente, sólo las polimixinas muestran actividad “in vitro” frente a aislamientos de bacilos gram-negativos resistentes a los carbapenemes. Sin embargo, el National Committee for Clinical Laboratory Standards (NCCLS) no incluye, actualmente, recomendaciones para la realización de las pruebas de sensibilidad para este grupo de antibióticos. Se determinó la actividad de colistín y la correlación entre las pruebas de difusión y dilución de este antibiótico frente a 186 aislamientos contemporáneos en el Hospital de Clínicas “José de San Martín”, siguiendo las recomendaciones generales del NCCLS. Se evaluaron dos puntos de corte: NCCLS 1981 (resistente £8 mmy sensible ³ 11mm) y R. Jones 2001 (resistente £ 11mm y sensible ³ 14mm). Utilizando el punto de corte del NCCLS 1981 se cometieron los siguientes errores: 0,5% “minor”; 2,2% “major” y 4,4% “very major”, mientras que con el propuesto por R. Jones 2001: 18,9% “minor”; 3,8% “major” y 0,5% “very major”. En conclusión, dado que el punto de corte utilizado por R. Jones 2001 disminuye el error “very major” pero aumenta el “minor” se recomienda la utilización de la concentración inhibitoria mínima (CIM) para confirmar la sensibilidad a colistín cuando sea usada en el tratamiento de infecciones, sin embargo no se detectó resistencia a colistín con halos de inhibición ³ a16 mm.

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September 3, 2011 at 12:43 pm Leave a comment

Ertapenem: Una nueva clase de carbapenem

Revista chilena de infectología 2003  V.20 N.4 P.270-276


Ertapenem is an new carbapenem that, compared to imipenem and meropenem, has a prolonged half life that allows its administration once daily and may be prescribed in severe infections treated as outpatients. Its antimicrobial spectrum is directed mainly against enteric Gram negative rods including betalactamase extended spectrum producers but its antibacterial activity against Pseudomonas spp or Acinetobacter spp is scarce. Besides ertapenem is active against Haemophilus influenzae y Streptococcus pneumoniae .including penicillin resistant strains and non Bacteroides strict anaerobes. It has no bactericidal activity against Enterococcus spp. Because of its favorable spectrum and safety profile ertapenem is well indicated in mixed infections as abdominal or pelvic sepsis, severe soft tissue infections, complexed urinary tract infections and community acquired pneumonia with suspicion of a mixed etiology …

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September 3, 2011 at 12:42 pm Leave a comment

Azithromycin for Prevention of Exacerbations of COPD

N Engl J of Med Aug.25, 2011 V.365  P.689-698

Richard K. Albert, M.D., John Connett, Ph.D., William C. Bailey, M.D., Richard Casaburi, M.D., Ph.D., J. Allen D. Cooper, Jr., M.D., Gerard J. Criner, M.D., Jeffrey L. Curtis, M.D., Mark T. Dransfield, M.D., MeiLan K. Han, M.D., Stephen C. Lazarus, M.D., Barry Make, M.D., Nathaniel Marchetti, M.D., Fernando J. Martinez, M.D., Nancy E. Madinger, M.D., Charlene McEvoy, M.D., M.P.H., Dennis E. Niewoehner, M.D., Janos Porsasz, M.D., Ph.D., Connie S. Price, M.D., John Reilly, M.D., Paul D. Scanlon, M.D., Frank C. Sciurba, M.D., Steven M. Scharf, M.D., Ph.D., George R. Washko, M.D., Prescott G. Woodruff, M.D., M.P.H., and Nicholas R. Anthonisen, M.D. for the COPD Clinical Research Network


Acute exacerbations adversely affect patients with chronic obstructive pulmonary disease (COPD). Macrolide antibiotics benefit patients with a variety of inflammatory airway diseases.


We performed a randomized trial to determine whether azithromycin decreased the frequency of exacerbations in participants with COPD who had an increased risk of exacerbations but no hearing impairment, resting tachycardia, or apparent risk of prolongation of the corrected QT interval.


A total of 1577 subjects were screened; 1142 (72%) were randomly assigned to receive azithromycin, at a dose of 250 mg daily (570 participants), or placebo (572 participants) for 1 year in addition to their usual care. The rate of 1-year follow-up was 89% in the azithromycin group and 90% in the placebo group. The median time to the first exacerbation was 266 days (95% confidence interval [CI], 227 to 313) among participants receiving azithromycin, as compared with 174 days (95% CI, 143 to 215) among participants receiving placebo (P<0.001). The frequency of exacerbations was 1.48 exacerbations per patient-year in the azithromycin group, as compared with 1.83 per patient-year in the placebo group (P=0.01), and the hazard ratio for having an acute exacerbation of COPD per patient-year in the azithromycin group was 0.73 (95% CI, 0.63 to 0.84; P<0.001). The scores on the St. George’s Respiratory Questionnaire (on a scale of 0 to 100, with lower scores indicating better functioning) improved more in the azithromycin group than in the placebo group (a mean [±SD] decrease of 2.8±12.8 vs. 0.6±11.4, P=0.004); the percentage of participants with more than the minimal clinically important difference of −4 units was 43% in the azithromycin group, as compared with 36% in the placebo group (P=0.03). Hearing decrements were more common in the azithromycin group than in the placebo group (25% vs. 20%, P=0.04).


Among selected subjects with COPD, azithromycin taken daily for 1 year, when added to usual treatment, decreased the frequency of exacerbations and improved quality of life but caused hearing decrements in a small percentage of subjects. Although this intervention could change microbial resistance patterns, the effect of this change is not known. (Funded by the National Institutes of Health; number, NCT00325897.)




Preventing Exacerbations of COPD — Advice from Hippocrates

Nikolaos M. Siafakas, M.D., Ph.D.

Severe acute exacerbations of chronic obstructive pulmonary disease (COPD) are devastating, life-threatening events; the 30-day mortality is greater than that with acute myocardial infarction (26% vs. 7.8%). Acute exacerbations of COPD dramatically change the course of the disease, since they are associated with a rapid decline in lung function and worsening quality of life.  They also represent a substantial economic burden to society. Prevention of exacerbations remains a primary goal of management3 but is difficult because the cause of acute exacerbations of COPD remains largely unknown.



September 3, 2011 at 12:34 pm Leave a comment


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