Decolonization and decontamination: what's their role in infection control?

PURPOSE OF REVIEW: Hospital-acquired infections cause up to 19% of infections in paediatric patients contributing to the spread of antimicrobial resistance. This review evaluates the effect of decolonization and decontamination in hospitalized children and neonates as an adjunct to standard infection control measures. RECENT FINDINGS: Few studies on decolonization and decontamination are available in children. The evidence about the effectiveness of daily chlorhexidine washcloths on bacteraemia in paediatric patients relies on a single randomized controlled trial, in neonates with central venous access in a single retrospective observational study. It is uncertain whether nasal mupirocin reduces methicillin-resistant Staphylococcus aureus carriage and infections in neonates, whereas oral chlorhexidine mouthwashes have not proven effective in children in intensive care settings. Scanty evidence demonstrates a reduction in the rate of ventilation-acquired pneumonia with digestive tract decontamination in paediatric patients and no studies are available in neonates. These strategies have not been extensively tested in resource-poor countries. SUMMARY: Strong evidence about the efficacy of decolonization and decontamination interventions exists in adult medicine but not in paediatric patients. There is an urgent need to understand how these interventions could be adapted to neonates and resource-poor settings in which the prevalence of hospital-acquired infections is higher.

Oral supplementation with Lactobacillus casei subspecies rhamnosus prevents enteric colonization by Candida species in preterm neonates: a randomized study.

BACKGROUND: Colonization by Candida species is the most important predictor of the development of invasive fungal disease in preterm neonates, and the enteric reservoir is a major site of colonization. We evaluated the effectiveness of an orally supplemented probiotic (Lactobacillus casei subspecies rhamnosus; Dicoflor [Dicofarm spa]; 6 x 10(9) cfu/day) in the prevention of gastrointestinal colonization by Candida species in preterm, very low birth weight (i.e., < 1500-g) neonates during their stay in a neonatal intensive care unit. METHODS: Over a 12-month period, a prospective, randomized, blind, clinical trial that involved 80 preterm neonates with a very low birth weight was conducted in a large tertiary neonatal intensive care unit. During the first 3 days of life, the neonates were randomly assigned to receive either an oral probiotic added to human (maternal or pooled donors') milk (group A) or human milk alone (group B) for 6 weeks or until discharge from the NICU, if the neonate was discharged before 6 weeks. On a weekly basis, specimens obtained from various sites (i.e., oropharyngeal, stool, gastric aspirate, and rectal specimens) were collected from all patients for surveillance culture, to assess the occurrence and intensity of fungal colonization in the gastrointestinal tract. RESULTS: The incidence of fungal enteric colonization (with colonization defined as at least 1 positive culture result for specimens obtained from at least 1 site) was significantly lower in group A than in group B (23.1% vs. 48.8%; relative risk, 0.315 [95% confidence interval, 0.120-0.826]; P = .01). The numbers of fungal isolates obtained from each neonate (P = .005) and from each colonized patient (P = .005) were also lower in group A than in group B. L. casei subspecies rhamnosus was more effective in the subgroup of neonates with a birth weight of 1001-1500 g. There were no changes in the relative proportions of the different Candida strains. No adverse effects potentially associated with the probiotic were recorded. CONCLUSIONS: Orally administered L. casei subspecies rhamnosus significantly reduces the incidence and the intensity of enteric colonization by Candida species among very low birth weight neonates.

Selective decontamination of the digestive tract improves survival in patients receiving differential lung ventilation.

In a review of the literature on differential lung ventilation (DLV) the average mortality was found to be 47%. The major cause of death (66%) was infection. The effect of a novel infection prevention regimen on the colonisation and infection rate of the respiratory tract and on outcome was studied in polytrauma patients. Nineteen patients who presented with asymmetric pulmonary contusion were treated with DLV (103 +/- 72 h) and conventional mechanical ventilation (CMV) (16 +/- 10 days). They were treated with selective decontamination of the digestive tract with topical non-absorbable antibiotics in combination with systemic antibiotic prophylaxis starting immediately after admission. In one patient colonisation of the respiratory tract was found with Staphylococcus aureus. This disappeared after continued systemic antibiotic prophylaxis. Colonisation with hospital-acquired Gram-negative bacteria or yeasts was not observed. No patient developed pneumonia throughout the period on conventional mechanical ventilation or on DLV. One patient died from cerebral injury. It is concluded that prolonged endobronchial intubation for DLV can be used without increased risk for pneumonia with this antibiotic regimen and that the very low mortality in this study may be attributed to the prevention of infectious complications.

Prevention of bacterial infection in the transplant recipient. The role of selective bowel decontamination.

Bacterial infections during the first month after liver transplantation remain a serious problem despite perioperative administration of systemic broad-spectrum antibiotics. These infections usually have been caused by aerobic gram-negative bacilli from the alimentary tract, and the most promising approach during the past decade is to eliminate or suppress these organisms by SBD. Several centers that have used SBD for prophylaxis have reported favorable results, but only one of the studies has been prospective and randomized. Based on the limited information now available, it seems that the efficacy of SBD is dependent on eliminating or suppressing aerobic gram-negative bacilli by the time of transplant surgery. This is an especially important point because successful SBD requires at least several days of treatment, and there are practical problems initiating and maintaining SBD in advance of unscheduled cadaver liver transplantation. Key areas for investigation are to establish by appropriately designed studies the efficacy of SBD and to examine the importance of achieving SBD prior to transplantation surgery.

Selective decontamination of the digestive tract and fungal infection in acute leukemia patients.

For prevention of infection we used an SD design including antibacterial (trimethoprim 480 mg/daily, sulfamerazine 720 mg/daily, and polymyxin 0.25 mg/daily) and antifungal (4-6 million IU nystatin/daily) components. We analyzed retrospectively 138 treatment periods in 108 patients. The intensified chemotherapy resulted in severe granulocytopenia below 0.1 x 10(9)/liter over 25.2 days. In 19 patients there was suspicion of major fungal infection; therefore they were given amphotericin B and 5-fluocytosine. Fourteen of them died; major fungal infections were documented in 5 cases. In 18% of all the deceased we found major fungal infections. There was a correlation between fungal infection, the late stages of the hematological malignancy, and the lesions on the oropharyngeal mucosa. However, in terms of the serological and culture findings no correlation appeared to exist between the group with and the group without fungal infection. The SD regime is meant to suppress the Candida cell concentration in the digestive tract but has no influence on Aspergillus in the respiratory tract.

Epidemiology of Pseudomonas aeruginosa in an intensive care unit using selective decontamination of the digestive tract.

Selective decontamination of the digestive tract (SDD) aims to reduce the rate of nosocomial infections in critical care patients. Pseudomonas spp. are common nosocomial pathogens and in this study isolates collected from patients and the environment during an SDD trial were examined. The study enrolled 161 SDD cases and 170 controls. Pseudomonads were isolated from 27% of SDD patients and 30% of controls. SDD partially suppressed colonization in the 'gastro-respiratory' mucosae but not in the rectum. A total of 108 isolates of pseudomonads were recovered from the environment. Resistance in rectal isolates was minimal but isolates from 'gastro-respiratory' sites showed increasing aminoglycoside resistance. Eighty-six per cent of aminoglycoside-resistant isolates from both patient groups and environment were pyocine type 1x. Episodes of infection were reduced in the SDD patients (6) compared with the controls (16), aminoglycoside-resistant strains being associated with zero episodes in SDD patients but with five in the control group.

Selective decontamination of the digestive tract: a life saver.

Selective decontamination of the digestive tract (SDD), a strategy designed to prevent or minimize the impact of infection by potentially pathogenic micro-organisms in critically ill patients requiring long-term mechanical ventilation, comprises four component protocols, aiming to control the three types of infection occurring in such cases: (i) a parenteral antibiotic, cefotaxime, administered for a few days to prevent primary endogenous infections typically occurring 'early'; (ii) the topical antimicrobials polymyxin E, tobramycin and amphotericin B employed throughout the stay in the intensive care unit to prevent secondary endogenous infections tending to develop 'late'; (iii) a high standard of hygiene to prevent exogenous infections that may occur throughout the stay in the intensive care unit; (iv) surveillance samples of throat and rectum to distinguish between these three types of infection, to monitor the compliance and the efficacy of the treatment, and to detect the emergence of resistance at an early stage. A recent, rigorous, meta-analysis examining 33 randomized SDD trials involving 5727 patients demonstrated a significant reduction in overall mortality (20%) and in the incidence of respiratory tract infections (65%); conclusive evidence that SDD saves the lives of critically ill patients and confirmation that SDD is now an evidence based medicine manoeuvre. This same meta-analysis found no instance of the emergence of resistance or of associated superinfections and/or outbreaks in any of the 33 studies during a period extending upwards of 10 years. By the criterion of cost-per-survivor, four recent randomized trials showed that patient survival is improved more cheaply by employing SDD than by the traditional approaches.

Lactic acid bacteria and the human gastrointestinal tract.

OBJECTIVE: This review summarises the effects of lactic acid bacteria on lactose malabsorption, bacterial/viral or antibiotic associated diarrhoea, and describes the impact of lactic acid bacteria on cancer and the fermentative products in the colon. RESULTS: Eight studies (including 78 patients) demonstrated that lactase deficient subjects absorbed lactose in yogurt better than lactose in milk, while two studies (25 patients) did not support this. Two studies (22 patients) showed that unfermented acidophilus milk was absorbed better than milk, while six studies (68 patients) found no significant differences. Addition of lactose hydrolysing enzyme, lactase, to milk improved lactose malabsorption in seven studies (131 lactose malabsorbers), while one study (10 malabsorbers) demonstrated no improvement. Lactic acid bacteria alleviated travellers' diarrhoea in one study (94 individuals) while a study including 756 individuals was borderline statistically significant. One study (50 individuals) did not find an effect of lactic acid bacteria on travellers' diarrhoea. Six studies (404 infants) demonstrated a significant effect of lactic acid bacteria on infant diarrhoea, while one study (40 infants) did not. Lactic acid bacteria moderated antibiotic associated diarrhoea in three studies (66 individuals), while two studies (117 individuals) were insignificant. CONCLUSIONS: Lactase deficient subjects benefit from a better lactose absorption after ingestion of yoghurt compared with milk and from milk added lactase, whereas ingestion of unfermented acidophilus milk does not seem to improve lactose absorption. The majority of studies support that lactic acid bacteria alleviate bacterial/viral induced diarrhoea, especially in infants, while the effect on antibiotic associated diarrhoea is less clear. Experimental studies indicate an effect of lactic bacteria on human cell cancer lines, but clinical evidence is lacking. A 'stabilising' effect of lactic acid bacteria on the colonic flora has not been documented.

Gut bacteria and health foods--the European perspective.

Probiotics, prebiotics, and synbiotics aimed at improving intestinal health currently represent the largest segment of the functional foods market in Europe, Japan and Australia. Evidence continues to emerge demonstrating that these ingredients have the potential to improve human health in specific intestinal disorders. The European Commission, through its 5th Framework Programme, is presently focusing on a substantial effort in the science of the intestinal microbiota, its interaction with its host and methods to manipulate its composition and activity for the improvement of human health and well being. Eight multicentre and multidisciplinary research projects now cover a range of topics required for the development of efficacious probiotic foods, from understanding probiotic mechanisms at a molecular level; developing technologies to ensure delivery of stable products; and demonstrating safety and efficacy of specific probiotics in defined treatment targets. This concerted research effort promises to provide us with an enhanced understanding of the human intestinal microbiota's role in health and disease, and new approaches and products to tackle a variety of intestinal problems.

Probiotics in health maintenance and disease prevention.

Probiotic microflora display numerous health benefits beyond providing basic nutritional value. They cooperatively maintain a delicate balance between the gastrointestinal tract and immune system. When this balance is disrupted, disease and inflammation result. Inflammation and over stimulation of the immune system by pathogenic bacteria are competitively inhibited by mucosal adherence of normal beneficial microflora. A healthy gastrointestinal tract with adequate mucus production and appropriate bacterial colonization prevents the overgrowth of pathogenic bacteria, modulates disease processes, and prevents widespread inflammatory disorders. The understanding of the function of probiotics in the maintenance of health and their importance in preventing disease serves to enhance the overall health of patients. With increasing understanding that beneficial microbes are required for health maintenance and disease prevention, probiotics may be commonly used as a therapeutic tool by health care practitioners in the not-too-distant future. This review presents a review of probiotics in health maintenance and disease prevention.

Selective decontamination of the digestive tract helps prevent bacterial infections in the early postoperative period after liver transplant.

UNLABELLED: In liver transplant (LTx) recipients, gut-associated bacterial and fungal organisms produce significant postoperative morbidity and mortality. We sought to assess the role of selective digestive decontamination (SDD) in preventing postoperative infections in a large single-center cohort of liver recipients transplanted under two non-simultaneous protocols. In 212 consecutive patients transplanted between 1/1/91 and 7/31/92, SDD (gentamicin 80 mg, polymyxin B 100 mg, nystatin suspension 10 mL) was employed, starting after induction of anesthesia and continued until POD 21 (SDD Group). In 157 consecutive patients transplanted between 1/1/93 and 12/31/93, SDD was not used (non-SDD Group). Both groups received IV vancomycin and cefotaxime prophylaxis. All culture-positive infections within the first 30 days post-LTx were recorded and classified as bacterial or fungal. Infection-related mortality (patients who died of infectious complications without any technical complication) was recorded. Groups did not differ in patient demographics, United Network for Organ Sharing (UNOS) status, use of veno-venous bypass, total/warm ischemia, or length of ICU stay. Infections developed in fewer SDD patients (56/212; 26%) than non-SDD patients (69/157; 44%) (p<0.001). The incidence of gram-negative infection was less in the SDD group (11% vs. 26%, p<0. 001) as was gram-positive infection (16% vs. 26%, p<0.001). Among patients who developed infection, there was no difference between groups in infections per patient. Primary graft non-function (PNF) developed in 20 SDD patients (7/20 had infections) and 8 non-SDD patients (6/8 had infections) (p=0.06). There were no differences in incidence of fungal infections or of infection-related mortality between groups. In the SDD group, there were fewer abdominal (p<0. 001), lung (p<0.001), wound (p<0.01), and urinary tract infections (p<0.05). CONCLUSION: Use of SDD in liver recipients early after transplant was associated with significantly fewer infections in the early postoperative period.

Infection control in patients undergoing mechanical ventilation: traditional approach versus a new development--selective decontamination of the digestive tract.

Nosocomial infections are major causes of morbidity and mortality in critically ill patients. Traditional infection control practices focus on preventing infection by controlling patient exposure to microorganisms within the patient's environment. We discuss these practices, along with the factors and organisms responsible for nosocomial infection in the patient undergoing mechanical ventilation. Despite traditional infection control measures, nosocomial infection continues to be a major problem. In recent years evidence has accumulated that points to bacterial colonization of the oropharynx and gastrointestinal tract as a major source of infection. A new technique, selective decontamination of the digestive tract, is being studied extensively for its ability to control colonization of the oral cavity and the gastrointestinal tract. In the technique nonabsorbable topical antibiotics are applied to the oropharynx and instilled into the stomach, and a short course of an intravenous cephalosporin is included. The technique appears a worthwhile addition to traditional infection control measures.

[Clinical significance of gastrointestinal decontamination under protected environment].

Many infections are caused by the patient's own oro-intestinal microbial flora under a protected environment. Thirty-eight patients with acute leukemia and two patients with blast crisis of chronic myelocytic leukemia were treated under a protected environment with or without prophylactic antibiotics. Antibiotics used for decontamination were vancomycin (V), polymyxin B (P) and nystatin (N). The number of patients in the VPN, PN and the no antibiotic group were 13, 13 and 14, respectively. While the intestinal microbial flora was almost completely eliminated in VPN group, the number of bacteria decreased slightly in PN group. The mean number of pharyngeal and anorectal bacterial species decreased most markedly in the VPN group, but there were no significant differences among the three groups. The number of febrile days was significantly lower in the VPN and PN group than the no antibiotics group with neutrophil counts of less than 100 microliters. The average number of episodes of infection per patient was lowest in VPN group and highest in the no antibiotic group. These data indicate that VPN administration is effective for eliminating intestinal bacterial flora and resultantly protecting endogenous infections.

Selective intestinal decontamination of the digestive tract for infection prophylaxis in severely burned patients.

An oral prophylactic antibiotic regimen aiming at suppression of the gram-negative rods and yeasts of the bowel flora was utilised in 48 severely burned patients to prevent burn wound colonisation. Only 17% of the patients had an actual or potential infection. Only one Pseudomonas infection occurred. The effect of this selective gastro-intestinal decontamination is discussed.

[The problem of systematic bacteriological examinations carried out early in premature infants]. / Le problème des examens bactériologiques systématiques pratiqués précocement chez les prématurés

Systematic bacteriological examinations of samples taken from the pharynges, the gastric juices and the meconium or the ano-rectal regions were carried out on 300 premature babies immediately on their admission to hospital. These examinations, which consisted in direct microscopic examination and in culturing the specimens, showed that usually a normal microbial flora was established in the mucous membranes of the digestive tracts but there were also abnormalities caused by contamination. There is therefore a limited but real value in the tests when they reveal massive bacterial contamination by the presence of microbes that could be at this stage of life dangerous to a premature baby. The results of the tests then suggest the necessity for antibiotic therapy.

[Fungi in feces, fungi in the intestines--therapeutic consequences?]. / Pilze im Stuhl, Pilze im Darm--therapeutische Konsequenzen?

Yeast in stool specimen are due to transient or commensal growth in the GI tract. Only in immune deficient subjects candida albicans may grow invasively in squamous epithelium. In dermal or vaginal mycosis systemic therapy does not add benefit to local measures. Candida-induced diarrhea in hospitalized patients following chemotherapy stop after a few days of nystatin treatment. Candida hypersensitivity syndrome does not exist, antifungal diet does not eradicate yeast. Stool examination for candida is of no sense because a positive finding is seen in up to 80% of healthy persons.