Optimization of empirical antibiotic selection for suspected Gram-negative bacteraemia in the emergency department

https://doi.org/10.1016/j.ijantimicag.2005.01.019Get rights and content

Abstract

A 1-year prospective study of patients with a positive blood culture and admitted through the emergency department (ED), was conducted to detect incidence and risk factors for resistance of Enterobacteriaceae to gentamicin and ciprofloxacin. A total of 245 emergency department-admitted patients had positive blood cultures, of which 131 (54%) grew Enterobacteriaceae. Of these 131 isolates, 32 (24%) were resistant to gentamicin and 37 (28%) to ciprofloxacin. Risk factors, by multivariate analysis, for gentamicin and ciprofloxacin resistance were: male gender (P < 0.05 and P < 0.01, respectively), nursing home residence (P < 0.001), diabetes mellitus (P < 0.05) and presence of a foreign body (P < 0.05 and P < 0.005). An additional risk factor for ciprofloxacin resistance was recent hospitalisation (P < 0.05). These data facilitate optimal selection of empirical antibiotic treatment of suspected Gram-negative infections, and may contribute to improved patient outcome and optimal use of antibiotics.

Introduction

Antibiotic treatment of suspected Gram-negative bacteraemia in the emergency department (ED) is empirical, pending cultures results [1], [2]. The physician may use the hospital antibiogram as a tool to direct this empirical treatment but these data are often not sufficiently specific. In our hospital, as in many others, gentamicin is used as the first-line drug to treat suspected Gram-negative infection in the ED [3], [4], [5] or, for patients with renal dysfunction, ciprofloxacin is used [6], [7], [8]. Over the last few years, we have observed a substantial number of septic episodes in which isolated Gram-negative bacteria were resistant to first-line treatment, with a possible risk of increased morbidity and mortality [9], [10], [11], [12], [13]. The aim of this study was to determine patients’ risk factors for resistance to the first-line agents for treatment of suspected Gram-negative bacteraemia in the ED in order to target these patients to receive broader spectrum antibiotics.

Section snippets

Methods

This project was conducted at the Shaare Zedek Medical Center, a 550 bed, university affiliated, general hospital. Most facilities are present, but there is no neurosurgery department and transplantations are not performed.

The microbiology laboratory receives about 10,000 blood culture sets annually, of which about 10% are positive, equivalent to 5% patient-specific positive cultures [14], [15]. With patient-specific cultures, if more than one culture, positive with the same organism was

Results

This study was conducted over 12 months, spanning the years 2000–2001. During this period, ±7500 blood culture sets were taken in the adult and paediatric EDs, from approximately 4700 patients. Of these cultures, 245 patient specific cultures were positive, 86 (35%) with Gram-positive organisms and 159 (65%) with Gram-negative. The incidence of the Gram-negative cultures was as follows: Enterobacteriaceae (131, 82.5%) Pseudomonas aeruginosa (7, 4.5%), Acinetobacter baumannii (8, 5%), and 13

Discussion

Patients admitted through the ED because of suspected Gram-negative infection (mostly urinary tract or intra-abdominal infection), usually receive empirical antibiotic treatment, pending relevant culture results [1], [2]. To choose appropriate treatment, the physician may follow one of two approaches. One is to choose a broad-spectrum antibiotic in order to cover all possible organisms including resistant strains [18]. Such an approach makes clinical sense but incurs the risk of rapidly rising

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