Abstract
BackgroundIn patients with suspected ventilator-associated pneumonia, a rapid etiological diagnosis is crucial as incorrect or delayed treatment in the first few hours leads to a worse prognosis and a higher mortality rate. This study examines the efficacy of a rapid antibiogram on bronchial aspirates in patients with suspected ventilator-associated pneumonia (VAP).MethodsThe direct gradient diffusion susceptibility testing method (GDM) on respiratory samples was compared with a standard broth microdilution method (BMD) after quantitative cultures in patients with suspicion of VAP. Samples were preselected by Gram staining (for good quality microbiological samples with a predominant single bacterial morphotype). The antibiotics tested were ceftazidime, ceftobiprole, ceftolozane-tazobactam, meropenem, doripenem, and tedizolid.ResultsOver a 16-month study period, 445 bronchial aspirate samples were selected from 1376 samples received at our laboratory from 672 adult patients. By direct plating on Mueller-Hinton agar, we recovered 504 (95.5%) of the 528 microorganisms identified by the standard semiquantitative method. Antimicrobial susceptibility testing by GDM was compared with the BMD method in 472 strains (216 Enterobacteriaceae, 138 P. aeruginosa and 118 S. aureus.) and 1652 individual microorganism-antimicrobial agent combinations. There was total agreement between both methods in 98% of combinations. The Kappa index between both techniques was excellent (over 80%). There was only one potential major error for P. aeruginosa susceptibility to ceftazidime.ConclusionsThe six GDM strips directly placed on plated bronchial aspirates obtained from patients with a suspicion of VAP provided accurate and reliable susceptibility results within 24 h.
Highlights
Hospital-acquired pneumonia, and especially ventilatorassociated pneumonia (VAP), is one of the leading causes of infection and death in the healthcare setting [1,2,3,4,5]
Six gradient diffusion susceptibility testing method (GDM) strips were placed directly onto the plates which were incubated at 35 °C. minimum inhibitory concentration (MIC) readings were performed at 18–24 h under transmitted light
By direct plating on Mueller-Hinton agar, we recovered 504 (95.5%) of the 528 microorganisms retrieved by the standard semiquantitative method
Summary
Hospital-acquired pneumonia, and especially ventilatorassociated pneumonia (VAP), is one of the leading causes of infection and death in the healthcare setting [1,2,3,4,5]. Its incorrect or delayed treatment in the first few hours gives rise to a worse prognosis and higher mortality rate [7,8,9,10,11]. We observed that reporting a rapid GDM result for LRT samples gave rise to fewer days of fever and antibiotic administration until resolution of the VAP episode, reduced antibiotic consumption, less Clostridium difficile-associated diarrhoea episodes, lower costs of antimicrobial agents, and fewer days on mechanical ventilation [13]. In patients with suspected ventilator-associated pneumonia, a rapid etiological diagnosis is crucial as incorrect or delayed treatment in the first few hours leads to a worse prognosis and a higher mortality rate. This study examines the efficacy of a rapid antibiogram on bronchial aspirates in patients with suspected ventilatorassociated pneumonia (VAP)
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