Approaching zero: temporal effects of a restrictive antibiotic policy on hospital-acquired Clostridium difficile, extended-spectrum β-lactamase-producing coliforms and meticillin-resistant Staphylococcus aureus

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Abstract

A restrictive antibiotic policy banning routine use of ceftriaxone and ciprofloxacin was implemented in a 450-bed district general hospital following an educational campaign. Monthly consumption of nine antibiotics was monitored in defined daily doses (DDDs) per 1000 patient-occupied bed-days (1000 pt-bds) 9 months before until 16 months after policy introduction. Hospital-acquired Clostridium difficile, meticillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL)-producing coliform cases per month/1000 pt-bds were identified and reviewed throughout the hospital. Between the first and final 6 months of the study, average monthly consumption of ceftriaxone reduced by 95% (from 46.213 to 2.129 DDDs/1000 pt-bds) and that for ciprofloxacin by 72.5% (109.804 to 30.205 DDDs/1000 pt-bds). Over the same periods, hospital-acquisition rates for C. difficile reduced by 77% (2.398 to 0.549 cases/1000 pt-bds), for MRSA by 25% (1.187 to 0.894 cases/1000 pt-bds) and for ESBL-producing coliforms by 17% (1.480 to 1.224 cases/1000 pt-bds). Time-lag modelling confirmed significant associations between ceftriaxone and C. difficile cases at 1 month (correlation 0.83; P < 0.005), and between ciprofloxacin and ESBL-producing coliform cases at 2 months (correlation 0.649; P = 0.002). An audit performed 3 years after the policy showed sustained reduction in C. difficile rates (0.259 cases/1000 pt-bds), with additional decreases for MRSA (0.409 cases/1000 pt-bds) and ESBL-producing coliforms (0.809 cases/1000 pt-bds). In conclusion, banning two antibiotics resulted in an immediate and profound reduction in hospital-acquired C. difficile, with possible longer-term effects on MRSA and ESBL-producing coliform rates. Antibiotic stewardship is fundamental in the control of major hospital pathogens.

Introduction

There are continuing concerns over hospital-acquired infections (HAIs) caused by Clostridium difficile, meticillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL)-producing coliforms [1]. It is already known that these pathogens are associated with antibiotic consumption, with some classes encouraging certain organisms more than others [1], [2], [3]. Intensive use of cephalosporins or quinolones, for example, has been linked with increasing rates of C. difficile, MRSA and/or ESBL-producing coliforms, whilst reduced consumption has facilitated decreased rates of one or more of these pathogens [1], [2], [3], [4], [5]. As a response to high rates of HAIs, it was decided to impose a restrictive antibiotic policy banning the routine use of third-generation cephalosporins, specifically ceftriaxone, and quinolones throughout the hospital. Prospective surveillance programmes were set up to monitor rates of hospital-acquired C. difficile, MRSA and ESBL-producing coliforms. Previous studies have not necessarily monitored the effect of such a policy for a whole hospital, nor have they included surveillance of all three pathogens simultaneously. The aim of stewardship was primarily to reduce the number of C. difficile cases, although it was hoped that the policy would also impact on MRSA and ESBL-producing coliforms. This article describes how prescribing practices were changed and what happened after two key antibiotics were removed from first-line prescribing on a hospital-wide basis.

Section snippets

Antimicrobial policy implementation

Hairmyres Hospital is a 450-bed district general hospital in a rural area just outside Glasgow, UK. The hospital admits adult patients only, specialising in care of the elderly, respiratory, endocrinology and cardiology, with most surgical specialties represented, including orthopaedics, vascular, ear, nose and throat (ENT), and ophthalmology. There is an Accident & Emergency (A&E) department, a high dependency unit and an 8-bed Intensive Care Unit (ICU). Antimicrobial prescribing policies for

Results

Average monthly consumption of ceftriaxone reduced from 46.213 DDDs/1000 pt-bds for January–June 2008 to 2.129 DDDs/1000 pt-bds for June–November 2009 (95% reduction). Over the same periods, ciprofloxacin consumption decreased from 109.804 to 30.205 DDDs/1000 pt-bds (72.5% reduction). The pre-intervention hospital-acquisition MRSA rate during the initial 6 months was 1.187 cases/1000 pt-bds, decreasing to 0.894 cases/1000 pt-bds (25% reduction) for the final 6 months of the study; for C.

Discussion

Introducing and reinforcing a restrictive antimicrobial policy in this hospital had a rapid and profound effect on the rate of hospital-acquired C. difficile. The relationship between consumption of broad-spectrum antibiotics and C. difficile rates has already been established, with the highest risk for C. difficile infection within the first month following antibiotic use [1], [2], [3], [7]. Whilst the most significant association occurred between C. difficile rate and ceftriaxone consumption,

Acknowledgments

Frances Kerr, Catherine Irvine and Margaret Crookston (Pharmacy) helped with antimicrobial consumption data; nurses Christina Coulombe and Lorraine McWilliams helped collect and validate hospital-acquired infection data. The study could not have been performed without support from NHS Lanarkshire Antibiotic & Infection Group and Hairmyres medical staff.

Funding: No funding sources.

Competing interests: Sole conflicts of interest are previous conference support for SJD from Janssen-Cilag, Pfizer

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