Utility of an antibiotic guideline in hospital-associated infections

Introduction

Prompt initiation of appropriate antibiotic therapy improves outcome in critically ill patients [1]. In a tertiary-level ICU, we evaluated the appropriateness of, and adherence to an antibiotic guideline (based on local bacterial epidemiology) in CDC-defined hospital-associated infections.

Methods

We conducted a 6-month prospective observational study (April 2008 to October 2008) in consecutive ICU admissions of patients who satisfied investigator-adjudicated classification of ICU-acquired infections according to CDC criteria [2]. We assessed patient characteristics including severity of illness at admission, ICU length of stay (LOS), appropriateness of initial antibiotic choice as judged by in vitro sensitivity results and appropriateness of the current guideline. Results are presented as mean (SD) or median as appropriate.

Results

During the study period there were 101 antibiotic starts in 65 patients with sepsis secondary to ICU-acquired infections. Medical patients formed 44% of the study cohort; whilst 23% of patients were general surgical and the remaining 33% were post cardiothoracic surgery. The age and admission APACHE II score of the study cohort was 61.8 (16.3) years and 18.4 (5.6). The median LOS and ICU mortality of the cohort was 24 days and 27.6%. The most common CDC reportable diagnosis was clinical or microbiological confirmed pneumonia (PNU1/PNU2/LRI) (n = 57), followed by intra-abdominal infection (SSI-GIT) (n = 10) and urinary tract infection (SUTI) (n = 8). The culture positivity rate was 71.2%. The appropriateness of the ICU antibiotic guideline is summarised in Table 1. Monotherapy was used in 52.5% of episodes. The median length of antibiotic treatment with positive cultures was 7 days, and 5 days for culture negative episodes. In sepsis episodes with negative culture, antibiotics were stopped within 3 days in 17% of the episodes.

Table 1 Appropriateness of guideline-based antibiotic therapy

Conclusions

The study cohort had a high culture positivity rate (71%) in ICU-acquired sepsis. Our antibiotic guidelines gave an optimal empiric initial therapy in over 74% of episodes, with more than 50% of antibiotics started being monotherapy.