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Eradication of Syphacia muris from food-restricted rats without environmental decontamination.

Rodent pinworms rarely cause clinical disease, but infestation can affect experimental results. Our facility maintained a colony of Wistar rats for behavioral pharmacology studies that had been infested with Syphacia muris for > 15 years. The laboratory in which the animals were housed encompassed several rooms and contained a variety of complex behavioral equipment, including > 60 operant chambers. Several prior attempts to eliminate the pinworms were unsuccessful because of inadequate duration of treatment and incomplete environmental decontamination. Many of the rats in this colony were food-restricted as part of behavioral studies. Pinworms were eliminated from these animals by treating them with 450 ppm fenbendazole-containing feed for 3 consecutive weeks followed by 6 weeks of alternating every other week with standard rodent diet. Rats not on food restriction protocols were treated on the same schedule with 150 ppm fenbendazole-containing feed. Environmental decontamination of eggs from the behavioral equipment was not attempted. One year after treatment, the colony has remained free of S. muris. We adapted previously published protocols to our situation, including the problem of food-restricted rats and unfeasible environmental decontamination, to eradicate S. muris from our colony.

Administration, Oral↗

[Immediate decontamination. Comparative ergonomic study].

The standard procedures of decontamination between two patients were studied. As standards were chosen the OSHA's standards (Organization for Safety and Health Administration). The study was conducted by means of a "time and motion" analysis. The most important conclusions reached were: 1) it's impossible to complete the whole sequence in less than 10-15 minutes; 2) within this period one assistant didn't have any time to help the doctor at the chair; 3) consequently the doctor has to work alone for 10-15 minutes, unless a second assistant had been employed; 4) consequently, when we try to improve the decontamination, we need another assistant to make the work smoother, with a rise of the costs; 5) the systematic usage of the so called "barriers" is extremely time-wasting; 6) the only way to reduce the decontamination-time is the use of automatic devices, as the "Autosteril".

Cross Infection↗

[An analysis of hospital bacterial infections in cirrhotic patients undergoing selective intestinal decontamination].

Cirrhotic patients with ascites and low levels of ascitic fluid C3 and total protein and cirrhotic patients with gastrointestinal hemorrhage are at high risk of infection. Selective intestinal decontamination with oral norfloxacin is useful to decrease the incidence of infections in cirrhotic patients at high risk. This study analyzes hospital acquired bacterial infections in cirrhotic patients with ascites and low levels of total protein in ascitic fluid (n = 53) and cirrhotic patients with gastrointestinal hemorrhage (n = 26), both submitted to selective intestinal decontamination with norfloxacin during the hospitalization. Seven patients developed eight infections (8.8%): three patients with ascites and low levels of total protein in ascitic fluid and four patients with gastrointestinal hemorrhage (5.6% vs 15.3%, pNS). Gram negative bacilli were not isolated in any case, but Gram positive cocci were isolated in seven cases. These results suggest that Gram positive cocci must be empirically covered when infection is suspected in cirrhotic patients submitted to selective intestinal decontamination. The analysis of antibiograms in these infections showed a high sensitivity of Gram positive cocci to amoxycillin and clavulanic acid, which could be used as empirical treatment when infection is suspected in these patients.

Ascites↗

[Controlled decontamination of dynamic instruments].

This article describes the different possibility for the reduction of the decontamination in the operatories. The use of glutaraldheide appears the best choice among the numerous substances, or methods, offered by the market. A big improvement, using the potentiated glutaraldheide, is offered by the Autosteril; this is a device that allows the immediate decontamination of the unit, or a complete sterilization. The best advantage of the Autosteril is the automatization of the whole decontamination-cycle.

Automation↗

Decontamination and detoxification of mycotoxins.

Product decontamination and chemical detoxification are needed because preventive measures are not fully able to avoid contamination by mycotoxins. Criteria for safety evaluation studies of decontaminated products have to be established. Few chemical methods are available on an industrial scale; among them, ammoniation and the mixture monomethylamine-calcium hydroxide treatments show greatest promise of short-term application to oilseed cakes. Technical, economic, and public health aspects of these treatments are considered. Other decontamination techniques are briefly reviewed.

Decontamination↗

[Studies on inactivation of viruses in drinking and surface water. A contribution to the decontamination of water by field methods (author's transl)].

The suitability for field use of heating up to 80 degrees C and adding six different virucidal chemicals for decontamination of drinking and surface water was investigated using the viruses of Polio (vaccine strain), ECBO, Reo, bovine Parvo, HCC, Pseudorabies, ND and Vaccinia. The Parvovirus (concentration 10(5) TCID50/ml) heated to 80 degrees C could not be inactivated completely in drinking water within one hour; the Reovirus could after one hour only at 60 degrees C. The other viruses used lost their infectivity at 56 degrees C within 60 minutes or at 60 degrees C within 20 minutes respectively. Heating therefore seems to be too circumstantial a method for viral decontamination of water and unreliable under field conditions. As to the chemical water additives tested, chloramine-T, hydrogen peroxide and sodium peroxide proved to be unsuitable in spite of virucidal activity. The amount of their concentration necessary for reliable virus inactivation makes the water unfit for drinking. Iodine, a calcium hypochlorite sample and potassium permanganate were useful. Because of its constant reaction in drinking water together with additional advantages, iodination of water would seem to be the best method at present for viral water decontamination usable under field conditions.

Calcium↗

Decontamination of urinary bags for rehabilitation patients.

Patients with neurologic injuries frequently have permanent indwelling or external catheters connected to disposable urinary bags. These patients routinely disconnect the bed bag during the day and apply a leg bag which can be concealed under their clothes. In our rehabilitation unit, both bags are discarded daily. This study investigated the possibility of safely reusing bed and leg bags. The procedure involved decontamination of the bags using 180 ml of a 1% solution of sodium hypochlorite. Initially, discarded bed and leg bags were decontaminated in the lab to ensure effectiveness of the procedure. Next, 22 patients reused their bed and leg bags with daily decontamination by the rehabilitation nursing staff. These bags were reused for two to eight days. Cultures of 137 bags were obtained to evaluate the technique. All cultures were negative. Baseline urine cultures for both time periods showed no significant difference in rates of bacteriuria. The potential savings for one year on our rehabilitation unit, with an average of 12 catheterized patients, would be approximately $39,000. Although this methodology conflicts with thoughts about not reusing disposable products, we have shown that the procedure can be done safely in rehabilitation patients and it is easy and inexpensive.

Bacteriuria↗

Potential 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure of Seveso decontamination workers: a controlled prospective study.

In 1976, an explosion at the Industrie Chimiche-Meda-Società Azionaria (ICMESA) plant in Meda, near the Italian town of Seveso, released a cloud of aerosol containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which contaminated the surrounding area. Clean-up of the highly polluted area of Seveso started on May 1980: in order to avoid exposure to significant levels of TCDD, safety measures are being used, but a potential exposure cannot be ruled out. A prospective study was set up at the beginning of the clean-up procedures, and laboratory tests are being used to evaluate trends among the decontamination workers. A reference group who met eligibility criteria at the preemployment examination was selected from employees of the same firm employing the decontamination was selected from employees of the same firm employing the decontamination workers. Medical examinations and laboratory tests have been performed on both the exposed and nonexposed groups at the same facilities. Analysis of the first follow-up period did not show any remarkable changes in a battery of laboratory tests of the exposed and nonexposed groups.

Adult↗

Prospective study comparing the efficacy of prophylactic parenteral antimicrobials, with or without enteral decontamination, in patients with acute liver failure.

The efficacy of prophylactic parenteral antibacterials, with or without selective decontamination of the digestive tract, was compared in patients with acute liver failure (ALF) or severe acetaminophen hepatotoxicity. One hundred eight patients were randomized on admission to receive intravenous ceftazidime and flucloxacillin, plus either oral and enteral decontamination with colistin, tobramycin, and amphotericin B (group 1), or enteral amphotericin B alone (group 2). The two groups were comparable with respect to age, gender, etiology, coma grade on admission, international normalization ratio, presence of renal failure, Acute Physiology and Chronic Health Evaluation II score, and indicators of poor prognosis. Patients were monitored for clinical and microbiological evidence of infection. There were 15 episodes of infection in 10 of 47 patients (21%) in group 1 and 17 episodes in 12 of 61 patients (20%) in group 2. No differences in incidence, site, and causative organisms of infection were observed between the two groups. Overall, the incidence of infection was significantly higher in patients who developed encephalopathy than in those who did not. In patients who on arrival were not encephalopathic, the development of infection was associated with progression to coma. Duration of Liver Intensive Care Unit (LICU) stay was an independent risk factor for the development of infection. Parenteral antibiotics are effective at reducing the risk of infection in patients with ALF; enteral decontamination provided no additional benefit.

Adolescent↗

Selective decontamination of the digestive tract with norfloxacin in the prevention of ICU-acquired infections: a prospective randomized study.

The efficacy of a relatively cheap regimen of selective decontamination (SDD) was evaluated in a diverse population of ICU patients. Patients requiring prolonged ICU stay (greater than 5 days) were randomly allocated to a treatment group or control group. Control patients (n = 52) received perioperative antimicrobial prophylaxis and antibiotic treatment was instituted only on sound clinical and bacteriological criteria. Treated patients (n = 48) received gastro-intestinal and oro-pharyngeal decontamination with polymyxin E, norfloxacin, amphotericin B and systemic antibiotic prophylaxis with trimethoprim until decontamination was achieved. The rate of gram-positive infections was not altered by SDD. The incidence of gram-negative respiratory tract, urinary tract and line infections was significantly reduced from 44%, 27% and 15% respectively in the control group to 6%, 4% and 0% in the treatment group. Mortality from nosocomial sepsis and overall mortality were also significantly reduced from 15% and 54% to 0% and 31% respectively. The ICU stay was not reduced by SDD, nor was time on the ventilator or use of therapeutic antibiotics. The reduction in morbidity and mortality was achieved at a relatively low cost.

Bacterial Infections↗

The effect of selective decontamination of the digestive tract on colonisation and infection rate in multiple trauma patients.

122 multiple trauma patients staying in the ICU for 5 or more days and needing mechanical ventilation were investigated to determine the effect of selective decontamination of the digestive tract on prevention of infection. The (retrospectively studied) control group of 59 patients received no antibiotic prophylaxis. The infection rate during ICU-stay was 81%. Most infections were caused by potentially pathogenic microorganisms (PPM) from the oral cavity or the intestines (i.e. endogenous infections). The oropharynx and the intestines were rapidly colonised with ICU-associated gram-negative bacilli. After 2 weeks more than 80% of patients were found colonised. This secondary colonisation of the digestive tract is a very important stage in the pathogenesis of infections. Sixty-three patients were selectively decontaminated with nonabsorbable antibiotics, administered through the gastric tube even if peristalsis was absent. Emphasis was laid on the selective decontamination of the oral cavity, using topical application of an antibiotic paste. With this technique the oral cavity was free of PPM within 3 days in most patients. No secondary colonisation was found. Rectal colonisation decreased significantly after 5 days. Secondary colonisation occurred in 9 patients with PPM sensitive to the antibiotics used. The prophylactic regimen included systemic cefotaxim, directed against early endogenous infection. The suppression and after some time the absence of the endogenous source of PPM resulted in a significant reduction of colonisation and infection. The total infection rate decreased to 16%.

Administration, Topical↗

Mutagenic potentials of fumonisin contaminated corn following ammonia decontamination procedure.

Naturally contaminated corn implicated in an outbreak of equine leukoencephalomalacia (ELEM) in southeastern Arizona was analyzed for mutagenic potential using the Salmonella/microsome mutagenicity assay before and after treatment with the ammonia procedure. Crude acetonitrile: water (1 + 1) extracts of high-pressure/ambient temperature (HP/AT) ammonia decontaminated, HP/AT plus low pressure/high temperature (LP/HT), and non-ammoniated fumonisin contaminated corn were tested for mutagenic potentials. Relatively pure (approx. 90%) fumonisin B1 standard was also tested for comparison purposes. The results of this experiment indicate that there was no mutagenic potential for the fumonisin B1 standard at the concentrations tested (100 micrograms/plate). Also, neither the naturally-contaminated corn nor the ammonia decontaminated samples elicited a positive mutagenic response. Fumonisin B1 levels, as determined by HPLC methods, were reduced by an average of 79% via the ammonia decontamination process. It is encouraging to note that, while further work is necessary to increase the efficacy of the ammonia process to reduce fumonisin levels, the ammonia process did reduce fumonisin levels and no mutagenic potentials were apparent in the treated corn.

Ammonia↗

Antimicrobial prophylaxis in acute leukaemia: prospective randomized study comparing two methods of selective decontamination.

In a prospective study the efficacy of two regimens for selective decontamination of the digestive tract was studied in patients with acute leukaemia during remission induction therapy. Seventy-eight patients were randomized to receive either a combination of cotrimoxazole, polymyxin B and nystatin (group A) or a combination of nalidixic acid, polymyxin B, neomycin and nystatin. With both regimens the gastrointestinal tract could be decontaminated equally effectively from potential pathogens. In the oropharyngeal region the decontamination from Enterobacteriaceae was significantly better in group A (P less than 0.01). In both groups less than 10% of the acquired infections were caused by gram-negative bacilli and no gram-negative septicaemia occurred in either group. The median time interval until the first acquired infection was 17 days in group A and 36 days in group B, respectively (P less than 0.05). It is concluded that regimen A might be more effective than regimen B though both regimens prevent reliably severe gram-negative infections.

Acute Disease↗

E.O.R.T.C. Gnotobiotic Project Group: a prospective cooperative study of antimicrobial decontamination in granulocytopenic patients. Comparison of two different methods.

In a cooperative and prospectively randomized study, two different methods of antimicrobial decontamination of the digestive tract with oral, nonabsorbable antibiotics were compared in neutropenic patients. In the first treatment group, the antibiotics were selected on the basis of the outcome of sensitivity tests performed on the flora of the patients. The other treatment group was given a standard combination of neomycin, cephaloridin, polymyxin B or E and nystatin or amphotericin B. Complete data from a total of 35 patients were received at the Statistical Center, and a minimum of 1.5 oral washings and faecal samples per week arrived at the Central Bacteriological Laboratory. There was no substantial difference in the clinical parameters of the patients in both treatment groups. Both methods for decontamination were found to be effective. The incidence of acquired infections and the quality of decontamination were almost identical in both groups. As far as the average number of negative cultures per patient is concerned, the results for both treatment groups are well in line with data found in other studies using a combination of gentamicin, vancomycin and nystatin.

Acute Disease↗

Selective digestive decontamination by erythromycin-base in a polyvalent intensive care unit.

OBJECTIVE: To study the effect of selective digestive tract decontamination by erythromycin-base on the incidence of carriage and infection with MR Enterobacteriaceae producing an extended spectrum beta-lactamase (ESB). DESIGN: After a 10-week prospective survey to ascertain the baseline incidence in two bays (1 and 3) of the same ICU, bay 1 was compared with bay 3 during a further survey of 6 months. The patients in bay 1 received erythromycin-base. SETTING: Two non-contiguous bays, 1 and 3, of 4 beds, in the same polyvalent ICU of a university hospital. PATIENT: Consecutive patients with unit stay longer than 2 days; 34 patients were included during the control period, 43 in bay 1 (decontamination) and 46 in bay 3 (control) during the trial period. INTERVENTION: Erythromycin-base, 1 g t.i.d. in powder form administered by gastric tube to patients in bay 1 from admission to discharge. MEASUREMENTS AND RESULTS: Digestive tract carriage was monitored by cultures of gastric and rectal swab specimens, sampled twice a week. Enterobacteriaceae were isolated on Drigalski agar with incorporated ceftazidime (4 mg/l). In bay 1 there was a decrease in ESB producing Enterobacteriaceae (23% vs 10%, p = 0.0004) from rectal swab, especially in K. pneumoniae (15% vs 2%, p = 10(-5)), during the decontamination period in comparison to the control period. During the trial period the only differences observed between bays 1 and 3 were in the gastric samples: K. pneumoniae were less often isolated in bay 1 than in bay 3 (0% vs 3%, p = 0.03). Intestinal carriage with multiresistant Enterobacteriaceae occurred in 28% patients in bay 1 and 30% patients in bay 3 during the trial period (p = 0.79). Erythromycin-base did not delay the carriage by patients in bay 1 (log rank test p = 0.42). CONCLUSION: Erythromycin-base was not effective in preventing digestive tract carriage due to Enterobacteriaceae resistant to third generation cephalosporin by production of chromosomal cephalosporinase. The decrease in isolates containing K. pneumoniae in bay 1 cannot be definitively attributed to erythromycin-base, since the number of this species in bay 3 was low.

Adult↗

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.

Anti-Bacterial Agents↗

Mechanisms of failure to decontaminate the gut with polymixin E, gentamicin and amphotericin B in patients in intensive care.

The objective of the present work was to assess the possible mechanisms of the poor efficiency of selective decontamination of the digestive tract (SDD) in medical and surgical intensive care unit (ICU) patients. Sixty-four consecutive mechanically ventilated patients received gut decontamination with polymixin E, gentamicin and amphotericin B via a nasogastric tube and were assessed for oropharyngeal, gastric and fecal colonization and for the presence of each antibiotic in the stomach and feces. A decrease in fecal colonization with Escherichia coli was observed over 20 days but not with other gram-negative bacteria or gram-positive cocci. Fifteen and 26% of the fecal colonizing gram-negative bacteria were resistant to polymixin E and gentamicin, respectively, at admission. These proportions increased to up to 50% after 16 days of treatment. Although 50% of staphylococci were initially sensitive to gentamicin, all strains were resistant to this drug after four days of SDD. Both antibiotics were found in concentrations of less than 20 micrograms/g in 11 of 38 stools. Of these 38 stools, nine were not contaminated, 20 were colonized with resistant bacteria and 16 with strains sensitive to one antibiotic present in the stool. Therefore, the poor efficiency of gut decontamination observed was probably due to the great proportion of resistant strains on admission of the patients, to the selection of such resistant strains with SDD, to poor intestinal transit of the antibiotics, and to inactivation of the drugs by the feces. These results support stringent monitoring of fecal colonization in patients undergoing SDD in order to detect the fecal carriage of gram-positive and multiresistant gram-negative bacteria.

Adult↗

Strategy for antibiotic therapy in febrile neutropenic patients on selective antibiotic decontamination.

In a non-randomized prospective study the need for broad-spectrum antibiotic therapy was evaluated in selectively decontaminated neutropenic patients with fever. Fifty-two adult patients with a neutrophil count < 0.5 x 10(9)/l suffered 77 febrile episodes while receiving oral antibiotics for selective decontamination. Antibiotic treatment was only initiated if additional clinical signs or the microbiological culture results pointed to the likelihood of an infection. Treatment was either empirically based (broad-spectrum) or specific (narrow-spectrum). If a causative agent was identified, therapy was adjusted accordingly. If evidence of infection was lacking after 72-96 hours, the antibiotics were discontinued, and these patients were reexamined meticulously and repeatedly. For the 40 episodes without confirmed infection, the median duration of therapy was three days (range 0-13 days) and the survival rate 100%; for the 37 episodes with confirmed infection, the median duration of therapy was 12 days (range 1-49 days, p < 0.0001) and the survival rate 85%. After adjustment of therapy the final regimen was broad-spectrum in only 18% of treated episodes. None of the six deaths could be attributed to the withholding or stopping of broad-spectrum therapy. It is concluded that in febrile neutropenic patients on selective decontamination a standard therapy regimen with prolonged administration of broad-spectrum antibiotics is not necessary. After initial intervention antibiotic therapy can safely be tailored to the needs of the individual patient.

Adult↗