L. Silvestri

Descontaminación digestiva selectiva. ¿Por qué no aplicamos la evidencia en la práctica clínica?

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.

Infection control in the intensive care unit

Essentials in Clinical Microbiology.- Antimicrobials.- Infection Control.- Infections on ICU.- Special Topics.

Infection in the critically ill : an ongoing challenge

1 - Pneumonia Management in the Intensive Care Unit: an Integrated Approach.- 2 - Diagnostic Tools for Ventilator-Associated Pneumonia.- 3 - Cost-Effectiveness of New Technology to Reduce Catheter-Related Bloodstream Infections due to Central Venous Catheters.- 4 - Peritonitis: Priorities and Management Strategies.- 5 - Bacterial Translocation.- 6 - Practical Aspects of Antibiotic Prophylaxis in High-Risk Surgical Patients.- 7 - The Usefulness of Surveillance Cultures: a Prospective Cohort Study on the ICU.- 8 - Microbiology for the Critically Ill Patient Receiving Selective Decontamination of the Digestive Tract.- 9 - The Role of Surveillance Cultures in Containing Antibiotic Resistance.- 10 - Multi-Resistant Gram-Negative Bacilli: Impact of Antibiotic Restriction.- 11 - Multi-Drug-Resistant Staphylococci and Enterococci.- 12 - Therapeutic Options for the Treatment of Gram-Positive Infections.- 13 - Control of Methicillin-Resistant Staphylococcus aureus Outbreaks.- 14 - Oral Vancomycin in the Control of MRSA Outbreaks in the ICU.- 15 - Control of Acinetobacter Outbreaks with Oral Polymyxin.- 16 - An Approach to Controlling Acinetobacter Outbreaks in the ICUs.- 17 - Prevention of the Emergence of resistence.- Main Symbols.

Selective decontamination of the digestive tract: selectivity is not required

Dear Editor, We read Benus and colleagues’ article entitled ‘Impact of digestive and oropharyngeal decontamination on the intestinal microbrota in ICU patients’ [1]. Benus tested the hypothesis that selective decontamination of the digestive tract (SDD) may achieve its claimed benefits by leaving the anaerobic intestinal microbiota unaffected, which indicates a misunderstanding of SDD [2]. SDD was designed based on the observation that critical illness changes flora. Critical illness promotes a shift from normal (S. pneumoniae in the throat and E. coli in the gut) towards abnormal carriage (aerobic Gram-negative bacilli and methicillin-resistant Staphylococcus aureus) and overgrowth of both. Parenteral cefotaxime controls overgrowth of ‘normal’ flora, whereas abnormal flora is controlled by enteral polymyxin/tobramycin. There are 60 randomised controlled trials (RCT) and 10 meta-analyses confirming that SDD reduces pneumonia (72%), septicaemia (37%) and mortality (29%) without resistance emerging. Benus’s article focuses on ‘selectivity’. Anaerobes rarely cause infections; instead, the indigenous anaerobic flora contributes to physiology and control of abnormal carriage, i.e. it promotes colonisation resistance (CR) [3]. Antimicrobials suppressing anaerobes are ‘non-selective’, those leaving them virtually intact are ‘selective’. Using fluorescent in situ hybridization, Benus demonstrates that SDD impacts the indigenous flora, particularly Faecalibacterium prausnitzii, an anaerobic Gram-negative bacillus significantly reduced by high faecal tobramycin levels. They hypothesize that F. prausnitzii plays a role in maintaining CR, therefore SDD cannot be beneficial by leaving colonic microbiota unaffected. Interestingly, the faecal samples studied by Benus were collected from ICU patients enrolled in a recent RCT showing efficacy and safety of SDD [1]. The only conclusion is that SDD is effective and safe although not selective, as described by Vollaard et al. [3]. Donskey [4] wrote that SDD has tremendous potential although it is not truly selective. Six healthy volunteers were challenged with cefotaxime-resistant Enterobacter cloacae after intravenous administration of cefotaxime [3]. All became carriers, five experienced overgrowth, and all cleared the strain during pre-treatment without cefotaxime. Parenteral cefotaxime was chosen for SDD [2] as it has been shown to control overgrowth of normal flora through its high salivary and biliary concentrations. These levels are also bactericidal against Clostridium species, Gram-positive bacilli amongst the indigenous anaerobes, and are thought to contribute to CR [5]. Benus assessed the impact of SDD on CR in 17 ICU patients and reports a significant reduction in F. prausnitzii, which is hypothesized to play a role in maintaining CR, in contrast to Wensinck who showed that CR is based on anaerobic Gram-positive Clostridium species. Hence, Benus concludes that SDD is not selective. Benus fails to acknowledge Vollaard’s and Donskey’s work, although both are relevant to the assertion that SDD is a contradiction in terms, i.e., effective decontamination or eradication of gut overgrowth whilst maintaining complete selectivity does not make sense. However, the originators of SDD have always been aware of this contradiction in terms [2] preferring effectivity over selectivity, if negative consequences of non-selectivity are neutralised by enteral antimicrobials (polymyxin/tobramycin/amphotericin B). In conclusion, SDD exerts benefits via antimicrobial concentrations effective against overgrowth of normal and abnormal flora rather than by sparing the CR flora. The clinical impact of F. prausnitzii reduction in the critically ill is unclear.

Selective digestive decontamination and antibiotic resistance

Department of Critical Care, University Medical Center Groningen, The University of Groningen, Netherlands (AMGAdS); Department of Medical Microbiology, Amphia Hospital, Breda and Department of Medical Microbiology and Infectious Diseases, Vrije Universiteit Medical Center, Amsterdam, Netherlands (JAJWK); and Department of Medical Microbiology and Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands (MJMB)

Sepsis and Organ Dysfunction

Sepsis is one of the most significant causes of morbidity and mortality in intensive care units. The incidence of sepsis is still frequent, and the high mortality rates associated with the disease is increasing in the critically ill. Worldwide, 13 million people become septic each year and 4 million die. The pathophysiology of sepsis remain an enigma and the natural history is ever evolving.

Colistin Resistance during Selective Digestive Tract Decontamination Is Uncommon

D. F. Zandstra, J. H. Rommes, M. A. de la Cal, L. Silvestri, N. Taylor, H. K. F. van Saene ‹Department of Intensive Care, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands; Intensive Care Unit, Gelre Ziekenhuizen, Apeldoorn, The Netherlands; Department of Intensive Care Medicine, Hospital Universitario de Getafe, Getafe, Spain; Department of Emergency, Unit of Anesthesia and Intensive Care, Presidio Ospedaliero, Gorizia, Italy; Institute of Ageing and Chronic Diseases, University of Liverpool, Liverpool, United Kingdom

Inappropriate Dose of Enteral Antimicrobials Promotes Resistance

We read with interest the South African study based on a collection of separate case reports ([1][1]). The authors hypothesized that selective digestive decontamination (SDD) using enteral colistin (i.e., polymyxin E) and tobramycin probably contributed to the selection and carriage of a colistin-

Preventing Infection Using Selective Decontamination of the Digestive Tract

Selective decontamination of the digestive tract is an antimicrobial prophylaxis designed to prevent or minimize endogenous and exogenous infections in critically ill patients. The purpose of SDD is to prevent—or eradicate if initially present—the oropharyngeal and intestinal abnormal carrier state of potentially pathogenic microorganisms, mainly aerobic Gram-negative microorganisms, but also methicillin-sensitive Staphylococcus aureus (MSSA), and yeasts, leaving the indigenous flora predominately undisturbed.

Classification of ICU Infections

Classifying infections is crucial in any infection surveillance program, particularly in the intensive care unit (ICU). Time cutoffs, generally 48 h, have been accepted to distinguish community- from hospital-acquired infections, including ICU-acquired infections. However, many clinicians appreciate that an infection due to a microorganism carried by the patient on admission to the ICU and that develops 48 h of ICU stay cannot be considered as being a “true” ICU-acquired infection.