Direct E-test (AB Biodisk) of respiratory samples improves antimicrobial use in ventilator-associated pneumonia

Ventilator-associated pneumonia is the most frequently observed nosocomial infection in intensive care units, and it is associated with high morbidity and mortality. Early microbiological diagnosis and the initial administration of appropriate antimicrobial therapy are associated with decreased mortality and potentially reduced costs. Our study evaluates the clinical and financial impact of performing rapid antimicrobial susceptibility tests directly on samples obtained from the lower respiratory tract.

A prospective, randomized study was performed over a 2-year period. Patients who had a lower respiratory tract infection that was acquired during mechanical ventilation and for whom samples obtained from the respiratory tract were sent for culture were randomized to 1 of 2 groups. Samples were cultured for the control group, and results were reported using standard procedures. Samples were also cultured for the test subject group using standard procedures, but in addition, a rapid antibiogram was immediately performed by placing E-test antibiotic strips (AB Biodisk) directly on respiratory tract samples. Patients in the E-test group received a preliminary laboratory report when it became available. The 2 patient groups were compared according to the following variables: type and severity of underlying conditions, total days of antimicrobial use, number of defined daily doses, cost of acquisition of the antimicrobial agent per episode, days of fever, days receiving mechanical ventilation, days in the intensive care unit, incidence of Clostridium difficile-associated diarrhea, and mortality.

Reporting a rapid E-test was associated with fewer days of fever, fewer days of antibiotic administration until resolution of the episode of ventilator-associated pneumonia, decreased antibiotic consumption, less C. difficile-associated diarrhea, lower costs of antimicrobial agents, and fewer days receiving mechanical ventilation.

A rapid E-test of respiratory tract samples improves antimicrobial use in cases of ventilator-associated pneumonia.