Pilot trial of selective decontamination for prevention of bacterial infection in an intensive care unit

Topical antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving mechanical ventilation

BACKGROUND

Patients treated with mechanical ventilation in intensive care units (ICUs) have a high risk of developing respiratory tract infections (RTIs). Ventilator-associated pneumonia (VAP) has been estimated to affect 5% to 40% of patients treated with mechanical ventilation for at least 48 hours. The attributable mortality rate of VAP has been estimated at about 9%. Selective digestive decontamination (SDD), which consists of the topical application of non-absorbable antimicrobial agents to the oropharynx and gastroenteric tract during the whole period of mechanical ventilation, is often used to reduce the risk of VAP. A related treatment is selective oropharyngeal decontamination (SOD), in which topical antibiotics are applied to the oropharynx only. This is an update of a review first published in 1997 and updated in 2002, 2004, and 2009.

OBJECTIVES

To assess the effect of topical antibiotic regimens (SDD and SOD), given alone or in combination with systemic antibiotics, to prevent mortality and respiratory infections in patients receiving mechanical ventilation for at least 48 hours in ICUs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register, PubMed, and Embase on 5 February 2020. We also searched the WHO ICTRP and ClinicalTrials.gov for ongoing and unpublished studies on 5 February 2020. All searches included non-English language literature. We handsearched references of topic-related systematic reviews and the included studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and cluster-RCTs assessing the efficacy and safety of topical prophylactic antibiotic regimens in adults receiving intensive care and mechanical ventilation. The included studies compared topical plus systemic antibiotics versus placebo or no treatment; topical antibiotics versus no treatment; and topical plus systemic antibiotics versus systemic antibiotics.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included a total of 41 trials involving 11,004 participants (five new studies were added in this update). The minimum duration of mechanical ventilation ranged from 2 (19 studies) to 6 days (one study). Thirteen studies reported the mean length of ICU stay, ranging from 11 to 33 days. The percentage of immunocompromised patients ranged from 0% (10 studies) to 22% (1 study). The reporting quality of the majority of included studies was very poor, so we judged more than 40% of the studies as at unclear risk of selection bias. We judged all studies to be at low risk of performance bias, though 47.6% were open-label, because hospitals usually have standardised infection control programmes, and possible subjective decisions on who should be tested for the presence or absence of RTIs are unlikely in an ICU setting. Regarding detection bias, we judged all included studies as at low risk for the outcome mortality. For the outcome RTIs, we judged all double-blind studies as at low risk of detection bias. We judged five open-label studies as at high risk of detection bias, as the diagnosis of RTI was not based on microbiological exams; we judged the remaining open-label studies as at low risk of detection bias, as a standardised set of diagnostic criteria, including results of microbiological exams, were used. Topical plus systemic antibiotic prophylaxis reduces overall mortality compared with placebo or no treatment (risk ratio (RR) 0.84, 95% confidence interval (CI) 0.73 to 0.96; 18 studies; 5290 participants; high-certainty evidence). Based on an illustrative risk of 303 deaths in 1000 people this equates to 48 (95% CI 15 to 79) fewer deaths with topical plus systemic antibiotic prophylaxis. Topical plus systemic antibiotic prophylaxis probably reduces RTIs (RR 0.43, 95% CI 0.35 to 0.53; 17 studies; 2951 participants; moderate-certainty evidence). Based on an illustrative risk of 417 RTIs in 1000 people this equates to 238 (95% CI 196 to 271) fewer RTIs with topical plus systemic antibiotic prophylaxis. Topical antibiotic prophylaxis probably reduces overall mortality compared with no topical antibiotic prophylaxis (RR 0.96, 95% CI 0.87 to 1.05; 22 studies, 4213 participants; moderate-certainty evidence). Based on an illustrative risk of 290 deaths in 1000 people this equates to 19 (95% CI 37 fewer to 15 more) fewer deaths with topical antibiotic prophylaxis. Topical antibiotic prophylaxis may reduce RTIs (RR 0.57, 95% CI 0.44 to 0.74; 19 studies, 2698 participants; low-certainty evidence). Based on an illustrative risk of 318 RTIs in 1000 people this equates to 137 (95% CI 83 to 178) fewer RTIs with topical antibiotic prophylaxis. Sixteen studies reported adverse events and dropouts due to adverse events, which were poorly reported with sparse data. The certainty of the evidence ranged from low to very low.

AUTHORS' CONCLUSIONS

Treatments based on topical prophylaxis probably reduce respiratory infections, but not mortality, in adult patients receiving mechanical ventilation for at least 48 hours, whereas a combination of topical and systemic prophylactic antibiotics reduces both overall mortality and RTIs. However, we cannot rule out that the systemic component of the combined treatment provides a relevant contribution in the observed reduction of mortality. No conclusion can be drawn about adverse events as they were poorly reported with sparse data.

Impact of selective digestive decontamination on respiratory tract Candida among patients with suspected ventilator-associated pneumonia. A meta-analysis

The purpose here is to establish the incidence of respiratory tract colonization with Candida (RT Candida) among ICU patients receiving mechanical ventilation within studies in the literature. Also of interest is its relationship with candidemia and the relative importance of topical antibiotic (TA) use as within studies of selective digestive decontamination (SDD) versus other candidate risk factors towards it. The incidence of RT Candida was extracted from component (control and intervention) groups decanted from studies of various TA and non-TA ICU infection prevention methods with summary estimates derived using random effects. A benchmark RT Candida incidence to provide overarching calibration was derived using (observational) groups from studies without any prevention method under study. A multi-level regression model of group level data was undertaken using generalized estimating equation (GEE) methods. RT Candida data were sourced from 113 studies. The benchmark RT Candida incidence is 1.3; 0.9-1.8 % (mean and 95 % confidence intervals). Membership of a concurrent control group of a study of SDD (p = 0.02), the group-wide presence of candidemia risk factors (p < 0.001), and proportion of trauma admissions (p = 0.004), but neither the year of study publication, nor membership of any other component group, nor the mode of respiratory sampling are predictive of the RT Candida incidence. RT Candida and candidemia incidences are correlated. RT Candida incidence can serve as a basis for benchmarking. Several relationships have been identified. The increased incidence among concurrent control groups of SDD studies cannot be appreciated in any single study examined in isolation.

Nosocomial Infection Caused by Antibiotic-Resistant Organisms in the Intensive-Care Unit

Resistance to antimicrobial agents is an evolving process, driven by the selective pressure of heavy antibiotic use in individuals living in close proximity to others. The intensive care unit (ICU), crowded with debilitated patients who are receiving broad-spectrum antibiotics and being cared for by busy physicians, nurses, and technicians, serves as an ideal environment for the emergence of antibiotic resistance. Problem pathogens presently include multiply resistant gram-negative bacilli, methicillin-resistantStaphylococcus aureus, and the recently emerged vancomycin-resistant enterococci. The prevention of antimicrobial resistance in ICUs should focus on recognition via routine unit-based sur veillance, improved compliance with handwashing and barrier precautions, and antibiotic-use policies tailored to individual units within hospitals.

Topical antibiotics as a major contextual hazard toward bacteremia within selective digestive decontamination studies: a meta-analysis

BACKGROUND

Among methods for preventing pneumonia and possibly also bacteremia in intensive care unit (ICU) patients, Selective Digestive Decontamination (SDD) appears most effective within randomized concurrent controlled trials (RCCT's) although more recent trials have been cluster randomized. However, of the SDD components, whether protocolized parenteral antibiotic prophylaxis (PPAP) is required, and whether the topical antibiotic actually presents a contextual hazard, remain unresolved. The objective here is to compare the bacteremia rates and patterns of isolates in SDD-RCCT's versus the broader evidence base.

METHODS

Bacteremia incidence proportion data were extracted from component (control and intervention) groups decanted from studies investigating antibiotic (SDD) or non-antibiotic methods of VAP prevention and summarized using random effects meta-analysis of study and group level data. A reference category of groups derived from purely observational studies without any prevention method under study provided a benchmark incidence.

RESULTS

Within SDD RCCTs, the mean bacteremia incidence among concurrent component groups not exposed to PPAP (27 control; 17.1%; 13.1-22.1% and 12 intervention groups; 16.2%; 9.1-27.3%) is double that of the benchmark bacteremia incidence derived from 39 benchmark groups (8.3; 6.8-10.2%) and also 20 control groups from studies of non-antibiotic methods (7.1%; 4.8 - 10.5). There is a selective increase in coagulase negative staphylococci (CNS) but not in Pseudomonas aeruginosa among bacteremia isolates within control groups of SDD-RCCT's versus benchmark groups with data available.

CONCLUSIONS

The topical antibiotic component of SDD presents a major contextual hazard toward bacteremia against which the PPAP component partially mitigates.

Effect of selective decontamination on antimicrobial resistance in intensive care units: a systematic review and meta-analysis

BACKGROUND

Many meta-analyses have shown reductions in infection rates and mortality associated with the use of selective digestive decontamination (SDD) or selective oropharyngeal decontamination (SOD) in intensive care units (ICUs). These interventions have not been widely implemented because of concerns that their use could lead to the development of antimicrobial resistance in pathogens. We aimed to assess the effect of SDD and SOD on antimicrobial resistance rates in patients in ICUs.

METHODS

We did a systematic review of the effect of SDD and SOD on the rates of colonisation or infection with antimicrobial-resistant pathogens in patients who were critically ill. We searched for studies using Medline, Embase, and Cochrane databases, with no limits by language, date of publication, study design, or study quality. We included all studies of selective decontamination that involved prophylactic application of topical non-absorbable antimicrobials to the stomach or oropharynx of patients in ICUs, with or without additional systemic antimicrobials. We excluded studies of interventions that used only antiseptic or biocide agents such as chlorhexidine, unless antimicrobials were also included in the regimen. We used the Mantel-Haenszel model with random effects to calculate pooled odds ratios.

FINDINGS

We analysed 64 unique studies of SDD and SOD in ICUs, of which 47 were randomised controlled trials and 35 included data for the detection of antimicrobial resistance. When comparing data for patients in intervention groups (those who received SDD or SOD) versus data for those in control groups (who received no intervention), we identified no difference in the prevalence of colonisation or infection with Gram-positive antimicrobial-resistant pathogens of interest, including meticillin-resistant Staphylococcus aureus (odds ratio 1·46, 95% CI 0·90-2·37) and vancomycin-resistant enterococci (0·63, 0·39-1·02). Among Gram-negative bacilli, we detected no difference in aminoglycoside-resistance (0·73, 0·51-1·05) or fluoroquinolone-resistance (0·52, 0·16-1·68), but we did detect a reduction in polymyxin-resistant Gram-negative bacilli (0·58, 0·46-0·72) and third-generation cephalosporin-resistant Gram-negative bacilli (0·33, 0·20-0·52) in recipients of selective decontamination compared with those who received no intervention.

INTERPRETATION

We detected no relation between the use of SDD or SOD and the development of antimicrobial-resistance in pathogens in patients in the ICU, suggesting that the perceived risk of long-term harm related to selective decontamination cannot be justified by available data. However, our study indicates that the effect of decontamination on ICU-level antimicrobial resistance rates is understudied. We recommend that future research includes a non-crossover, cluster randomised controlled trial to assess long-term ICU-level changes in resistance rates.

FUNDING

None.

Selective decontamination of the digestive tract: the mechanism of action is control of gut overgrowth

PURPOSE

Gut overgrowth is the pathophysiological event in the critically ill requiring intensive care. In relation to the risk of developing a clinically important outcome, gut overgrowth is defined as ≥10(5) potential pathogens including 'abnormal' aerobic Gram-negative bacilli (AGNB), 'normal' bacteria and yeasts, per mL of digestive tract secretion. Surveillance samples of throat and gut are the only samples to detect overgrowth. Gut overgrowth is the crucial event which precedes both primary and secondary endogenous infection, and a risk factor for the development of de novo resistance. Selective decontamination of the digestive tract (SDD) is an antimicrobial prophylaxis designed to control overgrowth.

METHODS

There have been 65 randomised controlled trials of SDD in 15,000 patients over 25 years and 11 meta-analyses, which are reviewed.

RESULTS AND CONCLUSIONS

These trials demonstrate that the full SDD regimen using parenteral and enteral antimicrobials reduces lower airway infection by 72 %, blood stream infection by 37 %, and mortality by 29 %. Resistance is also controlled. Parenteral cefotaxime which reaches high salivary and biliary concentrations eradicates overgrowth of 'normal' bacteria such as Staphylococcus aureus in the throat. Enteral polyenes control 'normal' Candida species. Enteral polymyxin and tobramycin, eradicate, or prevent gut overgrowth of 'abnormal' AGNB. Enteral vancomycin controls overgrowth of 'abnormal' methicillin-resistant S. aureus. SDD controls overgrowth by achieving high antimicrobial concentrations effective against 'normal' and 'abnormal' potential pathogens rather than by selectivity.

Selective digestive tract decontamination in critically ill patients

INTRODUCTION

Selective decontamination of the digestive tract (SDD) has been proposed to prevent endogenous and exogenous infections and to reduce mortality in critically ill patients. Although the efficacy of SDD has been confirmed by randomized controlled trials (RCTs) and systematic reviews, SDD has been the subject of intense controversy, based mainly on an insufficient evidence of efficacy and on concerns about resistance.

AREAS COVERED

This article reviews the philosophy, the current evidence on the efficacy of SDD and the issue of emergence of resistance. All SDD RCTs were searched using Embase and Medline, with no restriction of language, gender or age. Personal archives were also explored, including abstracts from major scientific meetings; references in papers and published meta-analyses on SDD were crosschecked. Up-to-date evidence of the impact of SDD on carriage, infections and mortality is presented, and the efficacy of SDD in selected patient groups was investigated, along with the problem of the emergence of resistance.

EXPERT OPINION

SDD significantly reduces the number of infections of the lower respiratory tract and bloodstream, multiple organ failure and mortality. It also controls resistance, particularly when the full protocol of parenteral and enteral antimicrobials is used.

Selective decontamination of the digestive tract reduces pneumonia and mortality

Selective decontamination of the digestive tract (SDD) has been subject of numerous randomized controlled trials in critically ill patients. Almost all clinical trials showed SDD to prevent pneumonia. Nevertheless, SDD has remained a controversial strategy. One reason for why clinicians remained reluctant to implement SDD into daily practice could be that mortality was reduced in only 2 trials. Another reason could be the heterogeneity of trials of SDD. Indeed, many different prophylactic antimicrobial regimes were tested, and dissimilar diagnostic criteria for pneumonia were applied amongst the trials. This heterogeneity impeded interpretation and comparison of trial results. Two other hampering factors for implementation of SDD have been concerns over the risk of antimicrobial resistance and fear for escalation of costs associated with the use of prophylactic antimicrobials. This paper describes the concept of SDD, summarizes the results of published trials of SDD in mixed medical-surgical intensive care units, and rationalizes the risk of antimicrobial resistance and rise of costs associated with this potentially life-saving preventive strategy.

Antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving intensive care

BACKGROUND

Pneumonia is an important cause of mortality in intensive care units (ICUs). The incidence of pneumonia in ICU patients ranges between 7% and 40%, and the crude mortality from ventilator-associated pneumonia may exceed 50%. Although not all deaths in patients with this form of pneumonia are directly attributable to pneumonia, it has been shown to contribute to mortality in ICUs independently of other factors that are also strongly associated with such deaths.

OBJECTIVES

To assess the effects of prophylactic antibiotic regimens, such as selective decontamination of the digestive tract (SDD) for the prevention of respiratory tract infections (RTIs) and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 1), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register; MEDLINE (January 1966 to March 2009); and EMBASE (January 1990 to March 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of antibiotic prophylaxis for RTIs and deaths among adult ICU patients.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data and assessed trial quality.

MAIN RESULTS

We included 36 trials involving 6914 people. There was variation in the antibiotics used, patient characteristics and risk of RTIs and mortality in the control groups. In trials comparing a combination of topical and systemic antibiotics, there was a significant reduction in both RTIs (number of studies = 16, odds ratio (OR) 0.28, 95% confidence interval (CI) 0.20 to 0.38) and total mortality (number of studies = 17, OR 0.75, 95% CI 0.65 to 0.87) in the treated group. In trials comparing topical antimicrobials alone (or comparing topical plus systemic versus systemic alone) there was a significant reduction in RTIs (number of studies = 17, OR 0.44, 95% CI 0.31 to 0.63) but not in total mortality (number of studies = 19, OR 0.97, 95% CI 0.82 to 1.16) in the treated group.

AUTHORS' CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics reduces RTIs and overall mortality in adult patients receiving intensive care. Treatment based on the use of topical prophylaxis alone reduces respiratory infections but not mortality. The risk of resistance occurring as a negative consequence of antibiotic use was appropriately explored only in one trial which did not show any such effect.

Impact of Selective Decontamination of the Digestive Tract on Carriage and Infection Due to Gram-Negative and Gram-Positive Bacteria: A Systematic Review of Randomised Controlled Trials

Meta-analyses of randomised controlled trials of selective digestive decontamination have clinical outcome measures, mainly pneumonia and mortality. This meta-analysis has a microbiological endpoint and explores the impact of selective digestive decontamination on Gram-negative and Gram-positive carriage and severe infections. We searched electronic databases, Cochrane Register of Controlled Trials, previous meta-analyses and conference proceedings with no language restrictions. We included randomised controlled trials which compared the selective digestive decontamination protocol with no treatment or placebo. Three reviewers independently applied selection criteria, performed the quality assessment and extracted the data. The outcome measures were carriage and severe infection due to Gram-negative and Gram-positive bacteria. Odds ratios were pooled with the random effect model. Fifty-four randomised controlled trials comprising 9473 patients were included; 4672 patients received selective digestive decontamination and 4801 were controls. Selective digestive decontamination significantly reduced oropharyngeal carriage (odds ratio [OR] 0.13, 95% confidence interval [CI] 0.07 to 0.23), rectal carriage (OR 0.15, 95% CI 0.07 to 0.31), overall infection (OR 0.17, 95% CI 0.10 to 0.28), lower respiratory tract infection (OR 0.11, 95% CI 0.06 to 0.20) and bloodstream infection (OR 0.35, 95% CI 0.21 to 0.67) due to Gram-negative bacteria. Reduction in Gram-positive carriage was not significant. Gram-positive lower airway infections were significantly reduced (OR 0.52, 95% CI 0.34 to 0.78). Gram-positive bloodstream infections were not significantly increased (OR 1.03, 95% CI 0.75 to 1.41). The association of parenteral and enteral antimicrobials was superior to enteral antimicrobials in reducing carriage and severe infections due to Gram-negative bacteria. This meta-analysis confirms that selective digestive decontamination mainly targets Gram-negative bacteria; it does not show a significant increase in Gram-positive infection.

Single-drug therapy or selective decontamination of the digestive tract as antifungal prophylaxis in critically ill patients: a systematic review

Introduction

The objective of this study was to determine and compare the effectiveness of different prophylactic antifungal therapies in critically ill patients on the incidence of yeast colonisation, infection, candidemia, and hospital mortality.

Methods

A systematic review was conducted of prospective trials including adult non-neutropenic patients, comparing single-drug antifungal prophylaxis (SAP) or selective decontamination of the digestive tract (SDD) with controls and with each other.

Results

Thirty-three studies were included (11 SAP and 22 SDD; 5,529 patients). Compared with control groups, both SAP and SDD reduced the incidence of yeast colonisation (SAP: odds ratio [OR] 0.38, 95% confidence interval [CI] 0.20 to 0.70; SDD: OR 0.12, 95% CI 0.05 to 0.29) and infection (SAP: OR 0.54, 95% CI 0.39 to 0.75; SDD: OR 0.29, 95% CI 0.18 to 0.45). Treatment effects were significantly larger in SDD trials than in SAP trials. The incidence of candidemia was reduced by SAP (OR 0.32, 95% CI 0.12 to 0.82) but not by SDD (OR 0.59, 95% CI 0.25 to 1.40). In-hospital mortality was reduced predominantly by SDD (OR 0.73, 95% CI 0.59 to 0.93, numbers needed to treat 15; SAP: OR 0.80, 95% CI 0.64 to 1.00). Effectiveness of prophylaxis reduced with an increased proportion of included surgical patients.

Conclusion

Antifungal prophylaxis (SAP or SDD) is effective in reducing yeast colonisation and infections across a range of critically ill patients. Indirect comparisons suggest that SDD is more effective in reducing yeast-related outcomes, except for candidemia.

[Selective digestive decontamination. Why don't we apply the evidence in the clinical practice?]

Selective digestive decontamination (SDD) is a prophylactic strategy whose objective is to reduce the incidence of infections, mainly mechanical ventilation associated pneumonia in patients who require intensive cares, preventing or eradicating the oropharyngeal and gastrointestinal carrier state of potentially pathogenic microorganisms. Fifty-four randomized clinical trials (RCTs) and 9 meta-analysis have evaluated SDD. Thirty eight RCTs show a significant reduction of the infections and 4 of mortality. All the meta-analyses show a significant reduction of the infections and 5 out of the 9 meta-analyses report a significant reduction in mortality. Thus, 5 patients from the ICU with SDD must be treated to prevent pneumonia and 12 patients from the ICU should be treated to prevent one death. The data that show benefit of the SDD on mortality have an evidence grade 1 or recommendation grade A (supported by at least two level 1 investigations). The aim of this review is to explain the pathogeny of infections in critical patients, describe selective digestive decontamination, analyze the evidence available on it efficacy and the potential adverse effects and discuss the reasons published by the experts who advise against the use of SDD, even though it is recognized as the best intervention evaluated in intensive cares to reduce morbidity and mortality of the infections.

Predictive factors for pneumonia onset after cardiac surgery in Rio de Janeiro, Brazil

OBJECTIVE

To develop a predictive system for the occurrence of nosocomial pneumonia in patients who had cardiac surgery performed.

DESIGN

Retrospective cohort study.Setting. Two cardiologic tertiary care hospitals in Rio de Janeiro, Brazil.

PATIENTS

Between June 2000 and August 2002, there were 1,158 consecutive patients who had complex heart surgery performed. Patients older than 18 years who survived the first 48 postoperative hours were included in the study. The occurrence of pneumonia was diagnosed through active surveillance by an infectious diseases specialist according to the following criteria: the presence of new infiltrate on a radiograph in association with purulent sputum and either fever or leukocytosis until day 10 after cardiac surgery. Predictive models were built on the basis of logistic regression analysis and classification and regression tree (CART) analysis. The original data set was divided randomly into 2 parts, one used to construct the models (ie, "test sample") and the other used for validation (ie, "validation sample").

RESULTS

The area under the receiver-operating characteristic (ROC) curve was 69% for the logistic regression model and 76% for the CART model. Considering a probability greater than 7% to be predictive of pneumonia for both models, sensitivity was higher for the logistic regression models, compared with the CART models (64% vs 56%). However, the CART models had a higher specificity (92% vs 70%) and global accuracy (90% vs 70%) than the logistic regression models. Both models showed good performance, based on the 2-graph ROC, considering that 84.6% and 84.3% of the predictions obtained by regression and CART analyses were regarded as valid.

CONCLUSION

Although our findings are preliminary, the predictive models we created showed fairly good specificity and fair sensitivity.

Selective decontamination of the digestive tract reduces bacterial bloodstream infection and mortality in critically ill patients. Systematic review of randomized, controlled trials

A systematic review and meta-analysis of randomized controlled trials (RCTs) of selective decontamination of the digestive tract (SDD) was undertaken to evaluate the impact of this procedure on bacterial bloodstream infection and mortality. Data sources were Medline, Embase, Cochrane Register of Controlled Trials, previous meta-analyses, and conference proceedings, without restriction of language or publication status. RCTs were retrieved that compared oropharyngeal and/or intestinal administration of antibiotics as part of the SDD protocol, with or without a parenteral component, with no treatment or placebo in the controls. The three outcome measures were patients with bloodstream infection, causative micro-organisms, and total mortality. Fifty-one RCTs conducted between 1987 and 2005, comprising 8065 critically ill patients were included in the review; 4079 patients received SDD and 3986 were controls. SDD significantly reduced overall bloodstream infections [odds ratio (OR), 0.73; 95% confidence interval (CI), 0.59-0.90; P=0.0036], gram-negative bloodstream infections (OR, 0.39; 95% CI, 0.24-0.63; P<0.001) and overall mortality (OR, 0.80; 95% CI, 0.69-0.94; P=0.0064), without affecting gram-positive bloodstream infections (OR, 1.06; 95% CI, 0.77-1.47). The subgroup analysis showed an even larger impact of SDD using parenteral and enteral antimicrobials on overall bloodstream infections, bloodstream infections due to gram-negative bacteria and overall mortality with ORs of 0.63 (95% CI, 0.46-0.87; P=0.005), 0.30 (95% CI, 0.16-0.56; P<0.001), and 0.74 (95% CI, 0.61-0.91; P=0.0034), respectively. Twenty patients need to be treated with SDD to prevent one gram-negative bloodstream infection and 22 patients to prevent one death.

Impact of selective decontamination of the digestive tract on fungal carriage and infection: systematic review of randomized controlled trials

OBJECTIVE

To determine the impact of the antifungal component of selective decontamination of the digestive tract on fungal carriage, infection and fungaemia.

DESIGN

Meta-analysis of randomized controlled trials of selective decontamination of the digestive tract.

STUDY SELECTION

Data sources included Medline, Embase, Cochrane Register of Controlled Trials, previous meta-analyses, personal communications and conference proceedings, without restriction of language or publication status. All randomized trials were selected that compared oropharyngeal and/or intestinal administration of antifungals amphotericin B or nystatin, as part of selective decontamination protocol, with no treatment in the controls. There were 42 randomized controlled trials with a total of 6,075 critically ill patients.

METHODS

Three reviewers independently applied selection criteria, performed quality assessment and extracted the data. The main outcome measures were patients with fungal carriage, patients with fungal infections and patients with fungaemia. Odds ratios were pooled with the random effect model.

MEASUREMENTS AND RESULTS

Enteral antifungals significantly reduced fungal carriage (odds ratio 0.32, 95% confidence interval 0.19-0.53) and overall fungal infections (0.30, 0.17-0.53). Fungaemia was not significantly reduced in the treatment group (0.89, 0.16-4.95).

CONCLUSIONS

Antifungals, as part of selective decontamination of the digestive tract, reduce fungal carriage and infection but not fungaemia in critically ill patients and may justify the inclusion of an antifungal component in the decontamination protocol.

Antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving intensive care

BACKGROUND

Pneumonia is an important cause of mortality in intensive care units. The incidence of pneumonia in such patients ranges between 7% and 40%, and the crude mortality from ventilator associated pneumonia may exceed 50%. Although not all deaths in patients with this form of pneumonia are directly attributable to pneumonia, it has been shown to contribute to mortality in intensive care units independently of other factors that are also strongly associated with such deaths.

OBJECTIVES

The objective of this review was to assess the effects of antibiotics for preventing respiratory tract infections and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (issue 3, 2003), which contains the Acute Respiratory Infections (ARI) Group specialised trials register; MEDLINE (January 1966 to September 2003); EMBASE (January 1990 to September 2003); proceedings of scientific meetings and reference lists of articles from January 1984 to December 2002. We also contacted investigators in the field.

SELECTION CRITERIA

Randomised trials of antibiotic prophylaxis for respiratory tract infections and deaths among adult intensive care unit patients.

DATA COLLECTION AND ANALYSIS

At least two reviewers independently extracted data and assessed trial quality.

MAIN RESULTS

Overall 36 trials involving 6922 people were included. There was variation in the antibiotics used, patient characteristics and risk of respiratory tract infections and mortality in the control groups. In 17 trials (involving 4295 patients) that tested a combination of topical and systemic antibiotic, the average rates of respiratory tract infections and deaths in the control group were 36% and 29% respectively. There was a significant reduction of both respiratory tract infections (odds ratio 0.35, 95% confidence interval 0.29 to 0.41) and total mortality (odds ratio 0.78, 95% confidence interval 0.68 to 0.89) in the treated group. On average 5 patients needed to be treated to prevent one infection and 21 patients to prevent one death. In 17 trials (involving 2664 patients) that tested topical antimicrobials alone (or comparing topical plus systemic versus systemic alone) the rates of respiratory tract infections and deaths in the control groups were 30% and 26% respectively. There was a significant reduction of respiratory tract infections (odds ratio 0.52, 95% confidence interval 0.43 to 0.63) but not in total mortality (odds ratio 0.97, 95% confidence interval 0.81 to 1.16) in the treated group.

REVIEWER'S CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics reduces respiratory tract infections and overall mortality in adult patients receiving intensive care. A treatment based on the use of topical prophylaxis alone reduces respiratory infections but not mortality. The risk of occurrence of resistance as a negative consequence of antibiotic use was appropriately explored only in the most recent trial by de Jonge which did not show any such effect.

Iseganan HCl: a novel antimicrobial agent

Iseganan HCl is an antimicrobial peptide under development for the prevention of oral mucositis, a severe consequence of some chemotherapy and radiation therapy regimens. Several attributes of iseganan make it an optimal candidate for study in this clinical situation where both local and systemic host defenses may be impaired. These include broad spectrum and rapid bactericidal activity, a lack of observed resistance and cross-resistance and stability in biological fluids. Clinical trials of patients receiving stomatotoxic chemotherapy followed by a haematopoietic stem cell transplant show iseganan reduces the occurrence of oral mucositis and ameliorates sequelae such as mouth pain, throat pain and difficulty swallowing. Iseganan is well-tolerated, which is partly attributable to a lack of systemic absorption following topical oral administration. Other promising areas of investigation include topical oral application for the prevention of ventilator-associated pneumonia and nebulisation for treatment of chronic lung infection in patients with cystic fibrosis. Future studies will expand on the role of iseganan as a novel antimicrobial.

Reduction in gram-positive pneumonia and antibiotic consumption following the use of a SDD protocol including nasal and oral mupirocin

The objective of this prospective, randomized, double-blind study was to evaluate the effect of the addition of mupirocin to the 'classical' topical SDD regimen (tobramycin 80 mg, polymyxin E 100 mg, amphotericin B 500 mg) on the development of ICU-acquired infections due to gram-positive bacteria. The study was carried out in an intensive care unit (ICU) of a 1400-bed community hospital. All patients admitted to the ICU during a 16-month period, who were expected to require mechanical ventilation for more than 24 hours, were randomized to receive either the 'classical' SDD regimen (Group A) or a modified regimen with mupirocin (Group B). Data from 223 patients requiring mechanical ventilation for at least 48 hours, who were neither infected nor receiving antibiotics on ICU admission, was analysed. A 2% paste containing tobramycin, polymyxin E and amphotericin B was applied every 6 hours in the oropharynx to the patients in Group A, while in Group B this formula was modified with the addition of 2% mupirocin. In Group B 0.2 ml of a 2% mupirocin ointment was also applied four times daily in both nostrils. Patients in Group A received a soft paraffin ointment as a placebo indistinguishable from mupirocin. Patients in both groups received the classic SDD regimen through the nasogastric tube. Systemic antibiotic prophylaxis was not used. Data on lower airway infection, and blood infection, infections of intravascular catheters, antibiotic consumption and expenditures for antibiotics were analysed. The diagnosis of ventilator-associated pneumonia (VAP) was based on quantitative cultures of protected specimen brush samples (PSB) or on the results of distal broncho-alveolar lavage (BAL). One hundred and four patients received the 'classical' SDD and 119 the modified regimen. Overall 29 patients, 20 in Group A and nine in Group B (p < 0.02) had a total of 33 cases of pneumonia. There were 23 episodes of pneumonia in Group A and 10 in Group B (p < 0.02). Gram-positive bacteria were isolated from samples in 17 episodes in Group A and six in Group B (p < 0.02). Staphylococcus aureus was isolated in nine cases of pneumonia in Group A and once in the 'mupirocin' group (p < 0.05). MRSA were isolated in seven out of nine cases in Group A and in the only case in Group B. There were no differences in the isolation of gram-negative bacilli. Antibiotic consumption and cost were lower in Group B. In conclusion, our data show that the topical use of a modified formula of SDD, with the addition of mupirocin to the oral paste and in the anterior nares, is associated with a reduction in lung infections caused by gram-positives and in a reduction in antibiotic consumption and in the overall expenditure for antibiotics.

Antibiotics for preventing respiratory tract infections in adults receiving intensive care

OBJECTIVES

Pneumonia is an important cause of mortality in intensive care units. The objective of this review was to assess the effects of antibiotics for preventing respiratory tract infections and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched MEDLINE, proceedings of scientific meetings and reference lists of articles from January 1984 to September 1997. We also contacted investigators in the field.

SELECTION CRITERIA

Randomised trials of antibiotic prophylaxis for respiratory tract infections and deaths among adult intensive care unit patients.

DATA COLLECTION AND ANALYSIS

Trials were assessed for quality and investigators contacted for additional information.

MAIN RESULTS

Overall 33 trials involving 5727 people were included. There was variation in the antibiotics used, patient characteristics and the risk of respiratory tract infections and mortality in the control groups. In 16 trials (involving 3493 patients) of a topical and systemic antibiotic combination, the average rates of respiratory tract infections and deaths in the control group were 33% and 28% respectively. There was a significant reduction of both respiratory tract infections (odds ratio 0.36, 95% confidence interval 0.30 to 0. 43) and total mortality (odds ratio 0.80, 95% confidence interval 0. 68 to 0.93). On average five patients needed to be treated to prevent one infection and 23 treated to prevent one death. In 17 trials (involving 2366 patients) of topical antimicrobials the rates of respiratory tract infections and deaths in the control groups were 30% and 24% respectively. There was a significant reduction of respiratory tract infections (odds ratio 0.57, 95% confidence interval 0.46 to 0.69) but not in total mortality (odds ratio 1.01, 95% confidence interval 0.84 to 1.22).

REVIEWER'S CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics can reduce respiratory tract infections and overall mortality in adult patients receiving intensive care. [This abstract has been prepared centrally.]

Prevention of nosocomial infection in a pediatric intensive care unit (PICU) through the use of selective digestive decontamination

OBJECTIVE

To assess the effectiveness of selective digestive decontamination (SDD) on the control of nosocomial infection (NI) in critically ill pediatric patients.

DESIGN

A prospective, randomized, non-blinded and controlled clinical microbiology study.

SETTING

The pediatric intensive care unit (PICU) of a tertiary level pediatric university hospital. CRITERIA FOR INCLUSION: Patients 1 month to 14 years old, who underwent some kind of manipulation or instrumentation (mechanical ventilation, vascular cannulation, monitoring of intracranial pressure, thoracic or abdominal drainage, bladder catheterization, peritoneal dialysis, etc.) and/or presented a neurological coma requiring a stay in the PICU of 3 or more days.

PATIENTS

Over a period of 2 years, 244 patients met the inclusion criteria; 18 patients were withdrawn because of protocol violation. The treatment group comprised 116 patients and the control group, 110 patients.

INTERVENTION

The treatment group received a triple therapy of colimycin, tobramycin and nystatin administered orally or via nasogastric tube every 6 hours. All patients with mechanical ventilation or immune-depression received decontamination treatment of the oropharyngeal cavity with hexitidine (Oraldine 0.5 mg/ml) every 6-8 hours in accordance with the PICU's conventional protocol.

METHOD

Up to 10 types of nosocomial infection were diagnosed following criteria of the Centers for Disease Control (CDC). The severity and manipulation of the patients on admission was assessed using the therapeutic intervention scoring system (TISS) and multi-organ system failure scores (MOSF).

MEASUREMENTS AND MAIN RESULTS

UNIVARIANT ANALYSIS: SDD did not significantly reduce the incidence of NI, antibiotic use, the length of stay, or mortality; although a small percentage of respiratory and urinary tract infections was detected, catheter-related bacteremia was the most common infection. MULTIVARIANT ANALYSIS: Controlling the risk factors for each child through log regression showed that SDD acted as a protective factor for more than 90% of the sample with respect to the appearance of respiratory and urinary tract infections, reducing the risk of such infections to 1/5 and 1/3, respectively.

CONCLUSIONS

SDD was effective in controlling respiratory and urinary tract infections in children admitted to the PICU, but it did not reduce the incidence of other types of nosocomial infection.

Effectiveness of antibiotic prophylaxis in critically ill adult patients: systematic review of randomised controlled trials

OBJECTIVE

To determine whether antibiotic prophylaxis reduces respiratory tract infections and overall mortality in unselected critically ill adult patients.

DESIGN

Meta-analysis of randomised controlled trials from 1984 and 1996 that compared different forms of antibiotic prophylaxis used to reduce respiratory tract infections and mortality with aggregate data and, in a subset of trials, data from individual patients.

SUBJECTS

Unselected critically ill adult patients; 5727 patients for aggregate data meta-analysis, 4343 for confirmatory meta-analysis with data from individual patients.

MAIN OUTCOME MEASURES

Respiratory tract infections and total mortality.

RESULTS

Two categories of eligible trials were defined: topical plus systemic antibiotics versus no treatment and topical preparation with or without a systemic antibiotic versus a systemic agent or placebo. Estimates from aggregate data meta-analysis of 16 trials (3361 patients) that tested combined treatment indicated a strong significant reduction in infection (odds ratio 0.35; 95% confidence interval 0.29 to 0.41) and total mortality (0.80; 0.69 to 0.93). With this treatment five and 23 patients would need to be treated to prevent one infection and one death, respectively. Similar analysis of 17 trials (2366 patients) that tested only topical antibiotics indicated a clear reduction in infection (0.56; 0.46 to 0.68) without a significant effect on total mortality (1.01; 0.84 to 1.22). Analysis of data from individual patients yielded similar results. No significant differences in treatment effect by major subgroups of patients emerged from the analyses.

CONCLUSIONS

This meta-analysis of 15 years of clinical research suggests that antibiotic prophylaxis with a combination of topical and systemic drugs can reduce respiratory tract infections and overall mortality in critically ill patients. This effect is significant and worth while, and it should be considered when practice guidelines are defined.

Chlorhexidine gluconate 0.12% oral rinse reduces the incidence of total nosocomial respiratory infection and nonprophylactic systemic antibiotic use in patients undergoing heart surgery

STUDY OFJECTIVE: The purpose of this study was to test the effectiveness of oropharyngeal decontamination on nosocomial infections in a comparatively homogeneous population of patients undergoing heart surgery.

DESIGN

This was a prospective, randomized, double-blind, placebo-controlled clinical trial. Experimental and control groups were selected for similar infection risk parameters. SEETTING: Cardiovascular ICU of a tertiary care hospital.

PATIENTS

Three hundred fifty-three consecutive patients undergoing coronary artery bypass grafting, valve, or other open heart surgical procedures were randomized to an experimental (n=173) or control (n=180) group. Heart and lung transplantations were excluded.

INTERVENTIONS

The experimental drug chosen was 0.12% chlorhexidine gluconate (CHX) oral rinse.

MEASUREMENTS AND RESULTS

The overall nosocomial infection rate was decreased in the CHX-treated patients by 65% (24/180 vs 8/173; p<0.01). We also noted a 69% reduction in the incidence of total respiratory tract infections in the CHX-treated group (17/180 vs 5/173; p<0.05). Gram-negative organisms were involved in significantly less (p<0.05) of the nosocomial infections and total respiratory tract infections by 59% and 67%, respectively. No change in bacterial antibiotic resistance patterns in either group was observed. The use of nonprophylactic IV antibiotics was lowered by 43% (42/180 vs 23/173; p<0.05). A reduction in mortality in the CHX-treated group was also noted (1.16% vs 5.56%).

CONCLUSIONS

Inexpensive and easily applied oropharyngeal decontamination with CHX oral rinse reduces the total nosocomial respiratory infection rate and the use of nonprophylactic systemic antibiotics in patients undergoing heart surgery. This results in significant cost savings for those patients who avoid additional antibiotic treatment.

Treatment and Control of Colonization in the Prevention of Nosocomial Infections

Patients frequently develop nosocomial infections that are caused by normal flora colonizing the patient at the time of admission, or by exogenous pathogens that are acquired and subsequently colonize the patient after admission to the hospital. To prevent nosocomial infections, a variety of strategies have been used either to prevent colonization from occurring, to eradicate colonizing organisms, or to prevent the progression from colonization to infection. These strategies include implementation of infection control measures designed to prevent acquisition of exogenous pathogens, eradication of exogenous pathogens from patients or personnel who have become colonized, suppression of normal flora, prevention of colonizing flora from entering sterile body sites during invasive procedures, microbial interference therapy, immunization of high-risk patients, and modification of antibiotic utilization practices. Because strategies that require widespread use of antimicrobial agents to suppress or eradicate colonizing organisms tend to promote emergence of multidrug-resistant pathogens, greater emphasis should be given to those strategies that prevent colonization from occurring or employ techniques other than administration of prophylactic antibiotics to eradicate colonization. Restricting inappropriate use of antibiotics should reduce the frequency with which patients become colonized and infected with multidrug-resistant organisms.

Prophylaxis with enteral antibiotics in ventilated patients: selective decontamination or selective cross-infection?

Selective decontamination of the digestive tract (SDD) has been evaluated as a method to prevent colonization and infection in ventilated patients in 40 trials. On the basis of an assumption that cross-infection would be reduced as a consequence of SDD and that this would distort the results of SDD studies that used concurrent controls, 14 studies used historic controls. To test this assumption, three observations from the two types of studies were compared. (i) The differences between observed and expected event rates for each study were used to perform a meta-analysis. This revealed that the summary odds ratios for bacteremia and respiratory infection were marked by significant heterogeneity (P > 0.95) and inconsistencies between those derived from studies with concurrent versus studies with historic controls. (ii) Where the data were available, the rates of acquisition of colonization in control groups were higher in studies with concurrent controls than in studies with historic controls. (iii) At least four studies with concurrent controls have shown a pattern of pathogenic isolates consistent with cross-infection between groups. These results are contrary to the initial assumption and suggest the possibility that SDD represents a major cross-infection hazard.

Prevention of nosocomial pneumonia

Prevention of nosocomial pneumonia becomes an achievable goal only to the extent that the mechanisms of infection are known. It is likely that there is variation among microorganisms, patients, type of care and intensive care, and practices that determines the relative efficacy of preventive measures. Certain procedures appear to be universally required and include adequate reprocessing of ventilation equipment and infection control measures in patient care. In contrast, many factors may affect the role of the stomach as a cause of nosocomial pneumonia, including enteral feeding procedures and gastric acidity. Differences in results between studies of preventive measures may reflect uncontrolled practice factors, which make the measures either more or less important. Selective decontamination of the digestive tract is a measure with potentially serious consequences, primarily cost and microbial resistance, and should be undertaken with care probably in selected high-risk patients. Other recommendations such as the use of sucralfate, which is effective in prevention of bleeding without clear side effects, are probably worth instituting based on existing evidence. The primary need may be for better reprocessing of equipment or hand washing and sterile gloves, or it may be several changes at once. Certainly an array of preventive measures is necessary, and there is probably no single procedure likely to solve such a complex problem. Use of the collective findings of many investigators needs to be made and strategies applied to each patient and setting. There has been a marked increase in our knowledge of nosocomial pneumonia, and effective measures for prevention are available. Application of these measures widely should reduce the frequency of respiratory complications. The microbiologic tools to compare bacterial isolates have been developed, and the course of events preceding infection of the patient can be demonstrated. The role of equipment, environment, other patients, personnel, colonization sites, and other factors can now be examined. Future studies should control for the many known factors that may predispose to nosocomial pneumonia to make the results meaningful. This would include definition of infection, patient risk factors, identification of microorganisms, details of enteral nutrition, type of stress ulcer prophylaxis, exposure to antimicrobial agents, and institutional resistance patterns. In some studies, surveillance cultures and molecular epidemiology techniques would be required. Large controlled multicenter studies are necessary to determine the significance of the results of promising smaller studies.(ABSTRACT TRUNCATED AT 400 WORDS)

The role of selective digestive tract decontamination on mortality and respiratory tract infections. A meta-analysis

PURPOSE

To review available clinical trials of selective digestive decontamination (SDD) in patients requiring intensive care.

DATA SOURCES

All relevant English-language articles from 1982 through 1992 were identified through MEDLINE search and article bibliographies.

STUDY SELECTION

Twenty-one articles were identified; 16 articles were selected for analysis based on inclusion and exclusion criteria.

DATA EXTRACTION

Occurrence rates for mortality, acquired pneumonia, and acquired tracheobronchitis were extracted for patients treated with SDD and for control patients. Cumulative risk differences were calculated for each of these outcomes.

RESULTS

There was no significant difference between cumulative mortality rates for control patients (0.262; n = 1,165) and patients receiving SDD (0.243; n = 1,105) (p = 0.291; beta error rate = 0.16). The acquired pneumonia greater than that in patients receiving SDD (0.074; n = 1,031) (p < 0.0001). The acquired tracheobronchitis rate in control patients (0.117; n = 549) was also significantly greater than that in patients receiving SDD (0.065; n = 494) (p = 0.004). The rate of acquired pneumonia due to Gram-positive bacteria was similar between the control patients (0.033; n = 660) and the SDD-treated patients (0.033; n = 646) (p = 0.933). Colonization with pathogenic Gram-positive bacteria and pneumonia due to antibiotic-resistant Gram-positive bacteria appeared to occur more frequently in SDD-treated patients.

CONCLUSIONS

These results suggest that SDD decreases the overall incidence of acquired pneumonia and tracheobronchitis in patients requiring intensive care. SDD had no apparent effect on the hospital mortality rate. The routine use of SDD cannot be supported by this meta-analysis. SDD may be useful in specific circumstances where a particular ICU or ICU population is found to have an excessive incidence of acquired infections. Any use of SDD should include careful patient surveillance for the emergence of infection due to bacteria not covered by the prophylaxis regimen and due to antibiotic-resistant bacteria.

[Selective digestive decontamination in patients under reanimation]

Nosocomial infections increase morbidity and mortality in hospitalized patients. ICU patients are at high risk of sustaining them, due to the high rate of invasive procedures and their poor health state. Conventional methods for decreasing the incidence of infection in ICU patients include handwashing, catheter care, strict antibiotic policy, and reduction of environmental sources of infection. Despite these measures, the colonization in these patients is always high, because of the presence of pathogens in the own patients' flora. Nosocomial pneumonia which is a major cause of mortality in ICU patients arises from retrograde colonization of the lung by pathogens originating from oro-pharyngeal and gastric secretions. Since 1984, selective decontamination of the digestive tract (SDD) has been advocated in ICUs to prevent from bacterial and fungal gastrointestinal/oropharyngreal colonization, nosocomial infection, subsequent multiple organ failure (MOF) and death. The SDD regimen is usually an extemporaneously prepared suspension of antimicrobial agents. Appropriate antibiotics for this regimen should ideally be nonabsorbable, to prevent from the development of resistant pathogens and avoid systemic toxicity. They should also be able to selectively eliminate enterobacteriaceae and yeasts, without decreasing the protective anaerobic flora. The most used combination is a suspension of colistin, amphotericin B and aminoglycoside, administered four times day through the nasogastric tube, in association with a paste consisting of 2 p. 100 colistin/amphotericin B/aminoglycoside, applied to the oropharynx. A parenteral antibiotic is also often co-administered during the first four days to prevent from early infections until the SDD regimen reaches its full effect; cefotaxime is usually used for this. SDD significantly decreases colonization rates in the oropharynx, gastrointestinal (GI) tract and trachea. This effects is primarily attributable to a decrease of Gram-negative bacilli (GNB) and yeasts, although several studies also reported decreased isolates of Gram-positive cocci (GPC). Oropharyngeal and GI colonization significantly decrease after four days of such a regimen, but tracheal decontamination in uncertain. Several studies recognized an emergence of GPC during or after SDD and resistance occurrence in GNB (especially against aminoglycosides). Recolonization occurs rapidly, about 4 to 8 days after the discontinuation of SDD. SDD decreases significantly the nosocomial infections, especially Gram-negative pneumonia. This benefit is most obvious in trauma patients, severely burned patients and after orthopic liver transplantation. Several studies reported a significant decrease in the overall rate of infections, especially extrapulmonary infections, including blood, urinary tract, wounds, abdominal, and catheter related infections. Despite a major decrease in infection rates with SDD, most studies did not show lowered mortality rates.(ABSTRACT TRUNCATED AT 400 WORDS)

Epidemiological impact of prolonged systematic use of topical SDD on bacterial colonization of the tracheobronchial tree and antibiotic resistance. A three year study

OBJECTIVE

to evaluate the effect of the prolonged systematic use of topical SDD (tobramycin 80 mg, polymyxin E 100 mg, amphotericin B 500 mg) on ICU ecology as expressed by changes in tracheal colonization and bacterial resistances.

DESIGN

Prospective microbiological survey.

SETTING

Polyvalent ICU of a 2000 beds general hospital.

PATIENTS

Data concerning bacterial strains isolated from the tracheo-bronchial aspirates of all the patients admitted to a polyvalent ICU over 3 consecutive periods of 12 months ('88, '89, '90) were prospectively entered in a database and subsequently analyzed. During a 3-year period 502 patients required artificial ventilation for more than 72 h and 332 of them ('89 and '90) were treated with SDD. All samples collected within 72 h from ICU admission were excluded as well as duplicate samples from the same patients.

INTERVENTION

All the patients admitted to the ICU in '89 and '90 and submitted to artificial ventilation for at least 24 h were routinely treated with topical SDD without i.v. antibiotic prophylaxis; in '88 SDD was not employed.

MEASUREMENTS AND RESULTS

Criteria for collecting sputum samples and microbiological procedures remained unchanged throughout the study-time. Positive sputum were significantly less in '89 (80.8% versus 92.3% p < 0.001) and this was due to a very sharp decrease in the isolation of Gram-negative strains from 43-28% (-64% p < 0.0001) involving both: Enterobacteriaceae (-45%) and Pseudomonaceae (-77%). In 1990; however, a new increase in Gram negative was observed, although the overall amount of Gram-negative was still 49% lower in '90 if compared to '88 (p < 0.0001). A dramatic increase in Pseudomonas isolation was the only factor responsible for the "rebound" observed. An increasing percentage of Pseudomonas developed a resistance towards tobramycin and only 45% of Pseudomonas strains turned out to be sensible to tobramycin in '90 against 79% in '88. A similar trend was registered for all aminoglycosides with the exception of amikacin. Gram-positive colonizations tended to increase (+63%) (p < 0.0001) and this was mainly due to Coagulase negative Staphylococci (+290% p < 0.0001) and S. pneumoniae, whereas S. aureus isolations decreased (-18%) but not significantly.

CONCLUSIONS

Our data suggest that the prolonged use of SDD is associated with dramatic changes in ICU ecology: the incidence of Gram negative colonization is significantly diminished by SDD whereas Gram positive tend to increase. Pseudomonas developed an increasing resistance towards tobramycin one of the components of the SDD formula we used.

Hospital-acquired gram-negative pneumonia in critically ill, injured patients

Hospital-acquired gram-negative pneumonia is a major problem in critically ill, injured patients. The currently available therapeutic interventions to prevent the disease process are of limited usefulness. This most likely reflects an incomplete understanding of the complex pathophysiologic mechanism and thus invites examination of alternative mechanisms. We have hypothesized that the lung's response to traumatic injury may be driving the local organ injury by generating an early, local pulmonary cytokine production independent of the systemic cytokine response or the intensive care unit environment. Understanding the local pulmonary cytokine response to traumatic injury and its effect on the pulmonary airspace's immunologic contents may yield targeted and clinically relevant therapeutic interventions. Currently, the successful treatment of hospital-acquired gram-negative pneumonia depends on a clear and consistent definition of the disease process, knowledge that therapy with a single antibiotic is effective, and use of a concise treatment protocol that provides for reassessment of the patient when antibiotic therapy appears to be ineffective.

Selective decontamination of the digestive tract in intensive care

Nosocomial infection in intensive care unit (ICU) practice is a common problem and is associated with abnormal carriage of Gram-negative aerobic bacilli in the gastrointestinal tract, resulting in endogenous infections. Selective decontamination of the digestive tract (SDD) is a regimen aimed at preventing or eradicating this abnormal carriage. A large number of trials examining SDD in ICU practice have been published, the vast majority showing a significant reduction in the incidence of nosocomial, Gram-negative infection. However, the impact on morbidity and mortality is much less certain. A recent meta-analysis has suggested a 10-20% reduction in mortality (3-6% absolute difference) with SDD. A discussion of these results is presented together with potential criticisms of SDD.

Selective decontamination of the digestive tract in intensive care patients: review and commentary

OBJECTIVE

To evaluate the benefits, risks, and costs of antimicrobial regimens used for selective decontamination of the digestive tract (SDD) in intensive care unit (ICU) patients.

DATA SOURCES

Information was obtained from clinical trials, review articles, abstracts, and textbooks. Key indexing terms included antibiotics, selective decontamination, and infections.

STUDY SELECTION

Research articles describing controlled clinical trials of SDD in medical or surgical ICU patients were reviewed. Trials that investigated transplant, cirrhotic, leukemic, or oncology patient populations were excluded.

DATA EXTRACTION

The details of studies that evaluated nosocomial infection or nosocomial pneumonia rates were extracted. These included study design, demographics, SDD regimens, severity of illness scores, and colonization, infection, and mortality rates.

DATA SYNTHESIS

The use of SDD in mechanically ventilated surgical or trauma ICU patients reduces the incidence of colonization, nosocomial pneumonia, and overall infection rates, but does not change the overall mortality rate. Administration of antibiotic and antifungal agents in a nasogastric suspension is required for SDD. The addition of systemic prophylactic antibiotics or oropharyngeal paste was not required to decrease nosocomial infections. The most frequently studied SDD regimen (colistin/amphotericin B/tobramycin) is not feasible for use in the US because of exorbitant drug costs. Less expensive alternatives include norfloxacin/nystatin, or colistin/nystatin/gentamicin.

CONCLUSIONS

Additional research is required before SDD regimens can be routinely recommended in surgical and trauma ICU patients. A multicenter study is warranted to determine the long-range benefits, potential for resistance, and cost-effectiveness of SDD.

A controlled trial in intensive care units of selective decontamination of the digestive tract with nonabsorbable antibiotics. The French Study Group on Selective Decontamination of the Digestive Tract

BACKGROUND

Selective decontamination of the digestive tract with topical nonabsorbable antibiotics has been reported to prevent nosocomial infections in patients receiving mechanical ventilation, and the procedure is used widely in Europe. However, it is unclear whether selective decontamination improves survival.

METHODS

We conducted a randomized, double-blind multicenter study in which 445 patients receiving mechanical ventilation in 15 intensive care units were given either prophylactic nonabsorbable antibiotics (n = 220) or a placebo (n = 225). Topical antibiotics (tobramycin, colistin sulfate, and amphotericin B) or a placebo was administered through a nasogastric tube and applied to the oropharynx throughout the period of ventilation. The main end points were the mortality rate in the intensive care unit and within 60 days of randomization.

RESULTS

A total of 142 patients died in the intensive care unit; 75 (34 percent) in the treatment group and 67 (30 percent) in the placebo group (P = 0.37). Mortality within 60 days of randomization was similar in the two groups (P = 0.40), even after adjustment for factors that were either unbalanced or individually predictive of survival in the two groups (P = 0.70). Pneumonia developed in 59 patients (13 percent) in the intensive care unit within 30 days of enrollment in the study (33 in the placebo group and 26 in the treatment group, P = 0.42). Pneumonia acquired in the intensive care unit and due to gram-negative bacilli was less frequent (P = 0.01) in the treatment group than in the placebo group. The total charges for antibiotics were 2.2 times higher in the treatment group.

CONCLUSIONS

Selective decontamination of the digestive tract does not improve survival among patients receiving mechanical ventilation in the intensive care unit, although it substantially increases the cost of their care.

Prevention of pneumonia by selective decontamination of the digestive tract (SDD)

Prevention of respiratory tract infections is only possible when the pathogenesis is known. Three types of infection can be distinguished: primary endogenous infections, caused by pathogens carried in the throat at the commencement of mechanical ventilation, generally develop early and can only be prevented by intravenous antibiotics. Secondary endogeneous infections, caused by hospital-acquired pathogens, generally develop later and can be prevented by selective decontamination of the digestive tract (SDD). The GI-tract is decontaminated by oral nonabsorbable antibiotics and for oropharyngeal decontamination a sticky antibiotic ointment is used. To date 16 controlled SDD trials in intensive care have been fully published. In all except one study, the pneumonia rate decreased significantly from 40%-50% in controls to about 10% in SDD-treated patients. All studies showed a consistent reduction of ventilator days, ICU-stay and an improved outcome in SDD-treated patients. However, in only few studies did these differences reach statistical significance. Selection of resistant strains has not been observed during prolonged use of SDD. Sucralfate reduces the pneumonia rate compared to H2-blockers or antacids by not interfering with the gastric barrier. However, gastric colonization is reduced rather than eliminated and sucralfate has almost no effect on oropharyngeal or tracheal colonization. Whether sucralfate is significantly better than a placebo remains to be established. SDD is superior to sucralfate in preventing both colonization and infection.