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Gastrointestinal decontamination for acute poisoning.

Acute poisoning remains a common cause of morbidity and even mortality in children and adults. The goal of gastrointestinal decontamination is to eliminate or to reduce the potentially life-threatening effects of the ingested poison. Methods of gastrointestinal detoxication in case of acute poisoning, such as induced emesis, gastric lavage, administration of activated charcoal and intestinal cleansing are discussed. As far as induced emesis is still concerned, only the administration of Ipecac-syrup can be retained. The controversy between emesis and gastric lavage still remains. For those toxins well adsorbed by activated charcoal, the administration of activated charcoal, followed or not by gastric lavage, is the treatment of choice. Single doses of activated charcoal can be insufficient. In certain kinds of poisoning, repeated doses of activated charcoal are advisable because of the interruption of the entero-hepatic and entero-enteric circulation. The benefit and the indications for intestinal cleansing in case of acute poisoning seem to be very limited.

Cathartics↗

Selective decontamination of the digestive tract and its value for patients in intensive care units.

Selective digestive decontamination (SDD) is a method that aims to eradicate the oropharyngeal and gastrointestinal carriage of potentially pathogenic micro-organisms (PPMO) by means of the application of high oropharyngeal and faecal antimicrobial concentrations. The SDD technique has proven its effectiveness in patients with profound granulocytopenia and has become commonplace in most European haematological services. A large number of trials most often uncontrolled or relying on historical controls have evaluated the use of SDD in intensive care patients. This article gives a summary of the effects of SDD on: colonisation of the different mucosae, infection, hospitalisation-time, mortality, cost-benefit aspects and the selection of resistant micro-organisms.

Agranulocytosis↗

Detection of bacteremia in emergency department patients at risk for infective endocarditis using universal 16S rRNA primers in a decontaminated polymerase chain reaction assay.

Prompt definitive diagnosis of acute bacterial endocarditis in febrile injection drug users (IDUs) remains problematic because of delays associated with blood culture. Rapid detection of bacteremia by polymerase chain reaction (PCR) by use of "universal" primers has been hampered by background bacterial contamination. Broad-range eubacterial primers selected from the 16S rRNA gene were used in a PCR assay coupled with a simple pre-PCR decontamination step. All PCR reagents were pretreated with the restriction enzyme AluI, which has multiple digestion sites in the amplicon but none in the primer sets. When 4 different bacterial species were spiked into healthy human blood specimens, the assay identified each pathogen with an analytic sensitivity of 5 bacteria/PCR reaction. A clinical trial with 51 febrile IDUs revealed that PCR had a sensitivity and specificity of 86.7% and 86.9%, respectively, versus blood culture. Importantly, all (8/8) patients with blood culture-positive infective endocarditis were determined to be positive by PCR. This assay provides a promising diagnostic for rapid identification of bacteremia, particularly valuable in acute care settings.

Bacteremia↗

Decontaminated single-use devices: an oxymoron that may be placing patients at risk for cross-contamination.

OBJECTIVE: To determine whether reprocessed single-use devices would meet regulatory standards for sterility and meet the same materials standards as a new device. DESIGN: The study included single-use and reusable biopsy forceps and papillotomes and a reusable stone retrieval basket. The suitability of these devices for cleaning and disinfection or sterilization was examined. METHODS: Testing of cleanability was conducted on devices contaminated with technetium 99-radiolabeled human blood. Instruments were cleaned using hospital recommended practices for manual cleaning. Gamma counts per second were determined before and after cleaning to localize contaminants, which were additionally visualized using light and scanning electron microscopy. X-ray photoelectron spectroscopy was used to quantify contamination elements on the materials tested. Residual bioburden testing on instruments contaminated with microorganisms suspended in coagulable sheep blood was carried out to establish the efficacy of disinfection and sterilization. RESULTS: All devices remained contaminated after cleaning, but single-use devices and the stone basket tended to be more heavily contaminated than reusable forceps and papillotomes. Cleaning procedures facilitated distribution of contaminants further into the lumens of the disposable forceps. Decreased concentrations of silicon and increased concentrations of carbon and nitrogen suggested that layers of silicon lubricant had been removed and contaminants were organic material. Reusable devices were effectively disinfected, but single-use devices were not. Sterilization could not eliminate the challenge microorganisms completely. CONCLUSIONS: None of the reprocessed single-use instruments were effectively cleaned, disinfected, or sterilized. This condition may provide an opportunity for the viability of nonresistant or nosocomial organisms and viruses. Additionally, reprocessing procedures may result in material destruction of fragile devices. Cost-saving initiatives that have inspired reprocessing of single-use devices, despite the absence of data establishing the efficacy of decontamination and the durability of materials throughout reprocessing, should be pushed into the background.

Blood-Borne Pathogens↗

Differential prognosis of gram-negative versus gram-positive infected and sterile pancreatic necrosis: results of a randomized trial in patients with severe acute pancreatitis treated with adjuvant selective decontamination.

Results of a previous randomized multicenter trial involving 102 patients with severe acute pancreatitis treated with or without adjuvant selective decontamination (SD) were analyzed additionally with regard to the bacteriologic status of (peri)pancreatic necrosis. The incidence of gram-negative pancreatic infection was significantly reduced in patients treated with SD (P = .004). Once such an infection develops, mortality increases 15-fold (P < .001) in comparison with that for patients with sterile necrosis. Among patients in whom only gram-positive infection of pancreatic necrosis was found, there was no significant increase in mortality. These results were similar in both treatment groups. In addition, the hospital stay was significantly longer in cases of gram-negative infected necrosis. The incidence of gram-positive infected necrosis in patients treated with SD did not increase. Gram-negative pancreatic infection can be prevented with adjuvant SD, thereby reducing mortality among patients with severe acute pancreatitis.

Acute Disease↗

Pathogenesis of multiple organ dysfunction syndrome: gut origin, protection, and decontamination.

Clinical and experimental studies performed over the past several decades have implicated bacterial and endotoxin translocation (BET) from the gut to distant organs in the pathogenesis of multiple organ dysfunction syndrome (MODS). Experimental studies in animals directed at maintaining the integrity of the intestinal mucosa have shown efficacy in preventing BET and the induction of distant inflammatory processes, suggesting that the egress of bacteria and their surface endotoxins might be pivotal in inducing MODS. However, clinical studies have failed to convincingly recapitulate these beneficial effects. Selective digestive decontamination, although it effectively decreases rates of respiratory infection, has failed to reduce MODS in critically ill patients and, except in certain patient subsets, has had no demonstrable effect on mortality. Nevertheless, the gut is an immunologically active organ that, irrespective of BET occurrence, appears to contribute significantly to the development of distant organ dysfunction following ischemia/reperfusion injury. Resuscitation strategies aimed at minimizing the inflammatory effects of gut-derived mediators, such as toxic oxygen species, appear promising in preventing the development of distant organ injury in the critically ill patient.

Animals↗

Randomized controlled trial of selective bowel decontamination for prevention of infections following liver transplantation.

Nonabsorbable antibiotics for selective bowel decontamination (SBD) sometimes are administered to liver transplant patients to prevent postoperative infections, but the efficacy of SBD is not known. Accordingly, we prospectively studied 69 patients randomly assigned to receive conventional prophylaxis with systemic antibiotics (control patients) or conventional prophylaxis plus oral nonabsorbable antibiotics for SBD (SBD patients). Overall rates of bacterial and/or yeast infections were nearly equal among control patients (42%) and SBD patients (39%). However, the infection rate at SBD key sites (abdomen, bloodstream, surgical wound, and lungs) was lower among patients who received the SBD regimen > or = 3 days before transplantation (23%) than among control patients (36%). Administration of the SBD regimen was complicated by gastrointestinal intolerance and noncompliance but not by increased stool colonization with antibiotic-resistant gram-negative bacilli. Practical problems associated with administering an SBD regimen to patients awaiting cadaver liver transplants limit the regimen's usefulness, but we found a trend toward reduced key site infection when the regimen was given > or = 3 days before transplantation.

Ampicillin↗

Long-term prophylaxis of infection by selective decontamination in leukopenia and in mechanical ventilation.

The autochthonous anaerobic bacterial flora in the mucosal layer of the gastrointestinal tract limits colonization by aerobic potential pathogens. This effect is called colonization resistance. Colonization of the digestive tract by potentially pathogenic microorganisms precedes infection in patients with leukopenia and in cases of mechanical ventilation and can be prevented by long-term administration of antimicrobial agents that spare the autochthonous anaerobic bacterial flora of the mucous membranes, a concept known as selective decontamination. Antimicrobial agents active against anaerobic flora reduce colonization resistance, permitting colonization by and overgrowth of potentially pathogenic microorganisms and possibly leading to infections with resistant microorganisms. A distinction can be made between antimicrobial agents that reduce colonization resistance and those that leave it intact by examining the effect of antimicrobial agents on aerobic intestinal flora of mice and humans.

Animals↗

Low dose oral tobramycin treatment for selective decontamination of the digestive tract: a study in human volunteers.

Tobramycin has been given orally to eight human volunteers for four successive days, to investigate its effect on the Gram-negative enterobacilli as well as on the endogenous anaerobic microflora. The effect was investigated in three treatment legs; i.e. in daily doses of 300 mg, in daily doses of 500 mg and thirdly in daily doses of 200 mg in combination with 1000 mg of neomycin. With 300 mg tobramycin daily, seven of eight volunteers had no Gram-negative bacilli in their faecal cultures by about four days after the onset of treatment. Their anaerobic micro-flora was slightly affected during treatment as evidenced by the appearance of low concentrations of beta-aspartylglycine in their stools. The other dose regimens were not significantly more effective in eliminating Gram-negative bacilli from the intestines; the anaerobic flora however, was more severely affected. Because evidence of induction of resistance was noticed it is recommended that if tobramycin is used for selective decontamination of the intestinal tract it should be given in combination with another antimicrobial drug such as polymyxin.

Adolescent↗

Prevention of catheter-associated gram-negative bacilluria with norfloxacin by selective decontamination of the bowel and high urinary concentration.

Oral norfloxacin prevented Gram-negative bacilluria in female patients with hip fractures, who needed medium-term transurethral catheterization. This was shown in a placebo-controlled double-blind study of 34 patients. Seventeen of these received a suspension containing 200 mg norfloxacin and 500 mg amphotericin B, twice daily. In the placebo group, six cases of Gram-negative bacilluria had occurred by day 7, as compared with no cases during a median time of catheterization of 23 days in the group on medication. Bacteriuria, either by Gram-positive cocci or by Gram-negative bacilli, was observed in 50% of patients on placebo by day 7; in the treatment group this was the case by day 17 (P less than 0.001). Subsequent bacteriuria with Gram-positive cocci was eliminated by nitrofurantoin (50 mg qid) within four days. Norfloxacin is very suitable for the prevention of Gram-negative bacilluria, because it decontaminates Gram-negative bacilli from the bowel, reaches high concentrations in urine and rarely produces resistant variants.

Aged↗

Prevention of bacterial colonization of the respiratory tract and stomach of mechanically ventilated patients by a novel regimen of selective decontamination in combination with initial systemic cefotaxime.

A novel regimen of selective decontamination (SDD) with initial systemic cefotaxime prevented bacterial colonization of the oropharynx and stomach in mechanically ventilated patients. In a three-group study of all patients receiving prolonged mechanical ventilation, patients in control groups A and B received antibiotics only when infection was present. In group A, antibiotics that disturb colonization resistance (CR) were used. In group B, antibiotics use was restricted to antibiotics not affecting CR. Patients in group C received SDD, consisting of norfloxacin, polymyxin E and amphotericin B, administered via a gastric tube and applied to the oropharynx. Group C patients further received an initial five day course of cefotaxime, 500 mg tid. The lower respiratory tract was colonized with microorganisms on admission in about half of the patients, and this persisted in both control groups. In group C, lower respiratory tract colonization was eliminated in all patients after five days. In both control groups about 90% of the patients acquired microbial colonization of the oropharynx and stomach, mostly with Gram-negative bacilli. In group C, only 12% and 24% of the patients acquired colonization of the oropharynx and stomach respectively (P less than 0.001). The oropharynx and stomach were the major sources of microorganisms causing lower respiratory tract infection in both control groups. In group C, elimination of oropharyngeal and gastric colonization completely prevented lower respiratory tract infection from these sources.

Adult↗

A controlled trial of selective decontamination of the digestive tract in intensive care and its effect on nosocomial infection.

Nosocomial infection is a major problem in intensive therapy units (ITUs) and a significant cause of mortality. Selective decontamination of the digestive tract (SDD) has been advocated as a means to reduce ITU morbidity and mortality. Ninety-one patients in a general ITU underwent SDD, consisting of topical polymyxin E, tobramycin and amphotericin B administered throughout the unit stay together with parenteral ceftazidime for the first three days, and were compared with 84 historical and 92 contemporaneous control patients who were treated conventionally. Twenty-seven historical and 32 contemporaneous control patients developed unit-acquired infections, in comparison with only three patients in the SDD group (P less than 0.01). Mortality in the SDD group (36%) was not significantly different from that in the other two groups (historical control 40%, contemporaneous control 43%). Screening specimens revealed a significantly higher rate of colonization with resistant Acinetobacter spp. in the contemporaneous control than in the other two groups of patients; infection caused by resistant bacteria did not occur. SDD did not lead to a significant reduction in the use of systemically-administered antibiotics when compared with either control group. SDD may be used selectively in an ITU without ill effects on those patients not receiving SDD; nevertheless, microbiological monitoring is needed to detect emergence of resistant bacteria in the unit.

Adolescent↗

Selective decontamination of the digestive tract (SDD) does not prevent the formation of microbial biofilms on endotracheal tubes.

The purpose of selective decontamination of the digestive tract (SDD) is to eradicate potentially disease-producing micro-organisms from the oropharynx and gastro-intestinal tract of intensive care unit (ICU) patients, thereby reducing the incidence of nosocomial sepsis, particularly pneumonia. Microbial biofilms form on endotracheal (ET) tubes even when SDD is being administered and may represent a persistent focus for infection. The aim of this investigation was to determine the susceptibilities of organisms adherent to ET tubes to SDD antibiotics (amphotericin B, tobramycin and polymyxin) and to measure the concentrations of these agents in the tracheal aspirates of 11 patients who were being mechanically ventilated. Following extubation, a section was cut from the tip of each ET tube and any adherent microorganisms subsequently isolated were identified and their MICs determined. Samples of tracheal aspirate were obtained three hours after administration of the SDD regimen and the concentrations of the constituent antimicrobials were measured. Enterobacteriaceae were not recovered from any of the tubes but six strains of Staphylococcus aureus, three Pseudomonas spp., three enterococci and four yeasts were isolated. Wide variations in the concentrations of all antibiotics were observed and in many cases they were below the MICs for the organisms isolated. In particular, tobramycin concentrations were uniformly less than the median MIC for the S. aureus isolates and this may account for the predominance of Gram-positive bacteria adherent to the ET tubes. Microbial biofilms attached to these tubes may have a role in the pathogenesis of nosocomial pneumonia in ICU patients.

Amphotericin B↗

Selective decontamination of the digestive tract and its role in antimicrobial prophylaxis.

Selective decontamination of the digestive tract (SDD) is an established form of infection prevention which relies upon local antibiotic action to afford suppression of potential pathogens while preserving 'colonization resistance' (CR). However, CR has never been shown conclusively to play a decisive role in either achieving or maintaining effective prophylaxis in patients and by employing absorbable antimicrobials or parenteral antibiotics, prophylaxis is actually achieved by both local and systemic action. The role of prophylaxis in neutropenic patients is also far from clear since morbidity and mortality remain the same whether or not prophylactic antibacterials are given and most patients still require empirical therapy for fever. In addition, the Gram-positive cocci, rather than Gram-negative bacilli presently predominate as pathogens. There is also an increasing trend towards including fungal and viral infection as targets for prophylaxis. Moreover, current anti-infective strategies are more akin to 'pre-emptive therapy' (PET) since the antimicrobials are available systemically and given at optimum therapeutic doses and there is little to distinguish treatment given to prevent colonization from progressing to infection from that used to arrest incipient infection or effect a cure of established infection. In contrast, SDD as originally conceived may well prove cost-effective for the prevention of infection in intensive care although neither the optimum regimen nor the patient group who would gain most benefit have been defined. None the less, by affording protection against Gram-negative sepsis, both SDD and PET would reduce the pressure on the clinicians to treat empirically and shift the emphasis once more on appropriate investigations which would involve the microbiologist more directly and immediately in patient care. Any savings from lowering the drug usage could then be diverted to improving diagnosis and providing the regular monitoring that is essential to the success of both PET and SDD.

Animals↗

Microbiological surveillance during selective decontamination of the digestive tract (SDD)

The use of selective decontamination of the digestive tract (SDD) as prophylaxis against nosocomial respiratory tract infection remains controversial, largely because of concerns that, in the long term, it may promote the emergence of antibiotic-resistant strains. This report describes the results of surveillance cultures and susceptibility testing undertaken during the course of a 2-year, double-blind study of the efficacy of SDD which was conducted in a respiratory intensive care unit (ICU). Surveillance specimens from the alimentary tract and trachea were obtained from each patient on admission and then twice weekly until 48 h after discharge from the unit. Specimens were cultured semiquantitatively and organisms from morphologically distinct colonies were identified by standard methods; the susceptibilities of these isolates were determined by the disc diffusion method. Five thousand, nine hundred and sixty surveillance samples from 239 patients were processed in this way. Compared with the placebo group, SDD caused a significant reduction in the incidence of colonization of the alimentary tract with aerobic Gram-negative bacilli (AGNB), and Candida spp. were almost totally eliminated. The incidence of colonization with enterococci increased in both groups, while the incidence of both colonization of the alimentary tract with strains of coagulase-negative staphylococci and methicillin-resistant Staphylococcus aureus and infection caused by these organisms increased in the SDD group. Acinetobacter spp. were the most common bacteria associated with unit-acquired colonization and lower respiratory tract infection in both groups. The acquisition of strains of Pseudomonas aeruginosa and cefotaxime- and/or tobramycin-resistant Enterobacteriaceae was significantly greater in the placebo group than in the SDD group, although tobramycin-resistant strains of Proteus, Morganella and Providencia spp. were isolated from three of 114 patients receiving SDD. The use of SDD did not lead to an overall increase in antibiotic resistance amongst the AGNB usually associated with ICU-acquired infection. However, colonization with strains which were either resistant to one or more of the antibiotic components of the regimen or which were not inhibited by the regimen was observed and may subsequently lead to infection.

Anti-Bacterial Agents↗

Short-term effect of the application of selective decontamination of the digestive tract on different body site reservoir ICU patients colonized by multi-resistant Acinetobacter baumannii.

The effect of a selective decontamination of the digestive tract (SDD) regimen including polymyxin and tobramycin on several body site reservoirs was compared between a test group and a control group in intensive care unit (ICU) patients with faecal multi-resistant Acinetobacter baumannii colonization. SDD significantly reduced faecal and pharyngeal carriage when compared with the control group at the end of ICU stay (48% versus 91%, P = 0.001, and 38.5% versus 78%, P = 0.01, respectively), but failed to reduce axillary colonization (75% versus 78%, P = 0.6). In addition, the isolation of A. baumannii from new clinical samples was lower in patients with SDD (45.5% versus 81%, P = 0.05). No resistance to polymyxin was observed. We conclude that the digestive tract reservoir of A. baumannii in ICU patients may be decreased by a SDD regimen.

Acinetobacter↗

Testing human hair for drugs of abuse. II. Identification of unique cocaine metabolites in hair of drug abusers and evaluation of decontamination procedures.

Two unique metabolites of cocaine, cocaethylene and norcocaine, were identified by GC/MS in the hair of cocaine users. Their presence cannot be explained by environmental contamination; thus, their presence together with cocaine provides convincing evidence that cocaine is excreted in hair after active cocaine administration. The amount of cocaine in hair predominated over all metabolites generally by a factor of 5-10. Two washing procedures were evaluated for their efficiency in removal of cocaine from environmentally contaminated hair. Neither procedure completely removed cocaine, suggesting that false positives can result from environmental contamination. Analysis of the methanolic wash of the hair of cocaine users also revealed the presence of cocaine metabolites, indicating that washing removes cocaine from the interior as well as from the exterior surface of hair during decontamination procedures.

Adult↗