Bacterial colonization of pressure ulcers: assessment of risk for bloodstream infection and impact on patient outcomes

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Summary

Background

Pressure ulcers (PUs) represent a major problem for hospitalized patients, health professionals and society.

Aim

To evaluate the impact of in-hospital PUs as a reservoir of multidrug-resistant organisms (MDROs), risk factor for bacteraemia and predictor of poor prognosis.

Methods

A prospective cohort study of patients with stage II or greater PUs hospitalized in a tertiary acute care university teaching hospital for more than 48 h was performed to evaluate colonization/infection by potential and/or multi-resistant hospital pathogens from April to December 2005 and from August 2009 to April 2010.

Findings

A total of 145 patients with stage II or greater PUs were included. Of these, 76.5% (111/145) had PUs colonized and/or infected with either S. aureus (20.7%), Gram-negative bacilli (32.5%), or both (46.8%) and most were MDROs (64.8%). Bacteraemia was detected in 50.5% (56/111) of the patients. The ulcers were considered to be the probable source of bacteraemia in 53.6% (30/56) of the episodes. Prior administration of antibiotics (P = 0.04) and infected wound (P < 0.001) were the variables independently associated with bloodstream infection as well as associated with a higher 30-day mortality rate; risk factors for the latter included hospitalization in ICU (P = 0.03) and mechanical ventilation use (P = 0.05).

Conclusions

Our results suggest that besides being a major reservoir of MDROs, patients with PUs constitute a high-risk population for bacteraemia with a poor outcome. Broad-spectrum antibiotics and infected wound were independent factors predisposing patients to both bacteraemia and death.

Introduction

Pressure ulcers (PUs) are a major world health problem. In particular, debilitated geriatric or bed-bound hospitalized patients in intensive care units (ICUs) are at a higher risk of developing PUs, because they are frequently immobile for long periods. Pressure ulcers cause significant morbidity, mortality and are a high economic burden to the healthcare system. They can also lead to serious infectious complications, including bacteraemia and sepsis.1, 2, 3

Epidemiologically important micro-organisms are often detected in these ulcers, but the distinction between colonized and infected ulcers remains a challenge. Infection is a frequent problem in chronic wounds as PUs increase markedly the risks of morbidity and mortality for patients.4, 5, 6

The micro-organisms most frequently involved with colonized PUs are Staphylococcus aureus and Gram-negative bacilli (GNB) such as Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. With increasing frequency, PUs are now colonized and/or infected with multidrug-resistant organisms (MDROs). Aerobic cultures often reveal meticillin-resistant S. aureus (MRSA) or multi-resistant GNB in these ulcers, which may represent reservoirs of MDROs or progress to local or systemic infection.5, 6, 7, 8, 9

Patients at high risk of developing infection who present with a colonized ulcer are often seriously ill, which results in prolonged hospital stays and use of invasive medical devices such as a urinary catheter, central vascular catheter and tracheal tube. Administration of antibiotics is also a risk factor for acquisition of MDRO infections.10, 11 The purpose of this study was to identify the risk factors that predispose patients who are hospitalized with PUs colonized by S. aureus and GNB to develop bloodstream infections/sepsis and to determine the prognostic factors associated with mortality.

Section snippets

Setting, study design, and definitions

This was a prospective cohort study of patients with stage II or greater PUs who had been admitted to a 510-bed tertiary teaching hospital during two time periods (April 2005 to December 2005 and August 2009 to April 2010). We performed a case–control study to assess the prognostic factor for mortality. The medical records of patients with PUs identified by active surveillance were reviewed for demographic and risk factor data.

Pressure ulcer staging

The PUs were classified according to a staging system: stage I

Results

A total of 145 patients with stage II or greater PUs, average age of 61.2 years (ranging from 20 to 101 years) and 69.6 days of hospitalization were included in this study. More than three-quarters (76.5%, 111/145) of these patients had colonized PUs. The frequency of patients with colonized ulcers due to S. aureus, GNB and both (S. aureus and GNB) was 20.7%, 32.5% and 46.8% respectively. It was observed that in 64.8% (72/111) of the patients the colonization of PUs was by one or more MDROs,

Discussion

Pressure ulcers are frequent occurrences, especially in elderly hospitalized patients, and may reflect the quality of care.4 Unfortunately, low compliance with hand hygiene, the single most important measure of prevention and control of nosocomial infections, in combination with incorrect patient handling and management by healthcare professionals must have contributed to the high PU and nosocomial infection rates shown in our study.24 In our hospital, of the 145 patients with stage II or

Conflict of interest statement

None declared.

Funding sources

None.

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