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Culture and decontamination methods affecting enumeration of phages infecting Bacteroides fragilis in sewage.

A new medium has been adapted for the growth of Bacteroides fragilis so that its phages can be recovered from environmental samples, and its efficiency has been assessed. Polyvinylidene difluoride membranes allow significantly higher recoveries among different membrane filters used to decontaminate the samples. In all cases, a number of phages remain in the filters and a percentage of them can be recovered by treatment with an eluant.

Bacteriophages↗

Influence of packaging and processing conditions on the decontamination of laboratory biomedical waste by steam sterilization.

The conditions for optimal steam decontamination of polypropylene bags half loaded with laboratory biomedical waste were studied (276 bags were processed). Controls were single-closed bags without water added or incisions made in the top, standing freely in an autoclave set at 121 degrees C. The average time required to reach 121 degrees C at the load center was 46 min for controls. A significant increase in this time occurred following addition of water to bags without incisions (60 min), with double bagging (60 min), or when using vertical containers (82 min). A significant decrease occurred when bags were slashed (37 min) or processed at 123 degrees C (32 min) or 132 degrees C (19 min). Horizontal containers or addition of water to slashed bags had no significant effect.

Journal Article↗

Inhibition of Escherichia coli translocation from the gastrointestinal tract by normal cecal flora in gnotobiotic or antibiotic-decontaminated mice.

Escherichia coli C25 maintained population levels of 10(9) to 10(10) per g of cecum and translocated to 100% of the middle mesenteric lymph nodes in gnotobiotic mice monoassociated with E. coli C25. Intragastric inoculation of these mice with the cecal contents from specific-pathogen-free mice reduced the population levels of E. coli C25 to 10(6) per g of cecum and completely inhibited translocation to the mesenteric lymph nodes. Intragastric inoculation with heat-treated, Formalintreated, or filtered cecal contents did not reduce the population levels of E. coli C25 or reduce the incidence of translocation of E. coli C25 to the mesenteric lymph nodes. Thus, viable bacteria apparently are required in the cecal contents inocula to reduce the population levels and the incidence of translocation of E. coli C25. Treatment with streptomycin plus bacitracin decreased the anaerobic bacterial levels in these gnotobiotic mice, allowing increased population levels of E. coli C25 and increased translocation to the mesenteric lymph nodes. E. coli C25 also translocated to the mesenteric lymph nodes of specific-pathogen-free mice treated with streptomycin and bacitracin before colonization with E. coli C25. The high cecal population levels of E. coli C25 in these antibiotic-decontaminated specific-pathogen-free mice apparently overwhelm any barrier to translocation exerted by the immunologically developed lamina propria of the specific-pathogen-free mice. Inoculation of gnotobiotic mice with a cecal flora also reduced the population levels of an indigenous strain of E. coli with a concomitant inhibition of translocation of the indigenous E. coli to the mesenteric lymph nodes. Thus, bacterial antagonism of the gastrointestinal population levels of certain indigenous bacteria, such as E. coli, by other members of the normal bacterial flora appears to be an important defense mechanism confining bacteria to the gastrointestinal tract.

Animals↗

Use of cetylpyridinium chloride and sodium chloride for the decontamination of sputum specimens that are transported to the laboratory for the isolation of Mycobacterium tuberculosis.

A method is presented for the decontamination, liquefaction, and concentration of sputum specimens that are in transport more than 24 h. The method is inexpensive, and culture results compare well with those obtained with the accepted N-acetyl-L-cysteine and sodium hydroxide method for the isolation of tubercle bacilli. The working solution, 1% cetylpyridinium chloride and 2% sodium chloride, is mixed in equal volumes with sputum before the specimens are shipped. Tubercle bacilli remained viable after 8 days of exposure to this solution. Only Lowenstein-Jensen medium was used because the cetylpyridinium chloride in the inoculum remains active on 7H10 or other agar base media and partially inhibits the growth of tubercle bacilli.

Acetylcysteine↗

Effectiveness of a decontamination method for donor corneas.

A retrospective study was made of the effectiveness of an eye bank decontamination and storage method. A comparison was made between microbial cultures taken from the limbus at enucleation and from scleral remnants recovered after surgery. Organisms were isolated from the limbus of 73% of donor eyes and from 4% of remnants. Standard eye bank procedures were found to eradicate gut and skin organisms, including candida, from donor tissue.

Cornea↗

Scrapie agent decontamination: implications for bovine spongiform encephalopathy.

Bovine spongiform encephalopathy probably results from the use of commercial diets containing scrapie-contaminated ingredients. Of all the chemical and physical decontamination procedures which are effective against conventional viruses, only high temperature autoclaving, high concentrations of sodium hypochlorite, and possibly molar sodium hydroxide, are useful against the group of unconventional transmissible agents which includes scrapie. The implications of this problem for the rendering industry and farm practice are discussed.

Animal Feed↗

Immediate postnatal decontamination as a means of obtaining axenic animals and human infants.

A technique not involving surgery is described for obtaining axenic (germ-free) newborn animals and human infants by decontamination immediately after birth. Three steps are involved: cleansing ther perineal region of the mother with an iodinated bactericidal solution, washing the newborn with the same solution, and after the newborn has been placed in a sterile isolater, administering a single oral dose of an antibiotic mixture previously determined to be active against the fecal and vaginal flora of the mother. All of the newborn obtained by means of this technique, including 13 piglets, 2 lambs, and 4 human infants, were found to be axenic throughout their stay in the isolators. Four piglets obtained by the same technique, but without adminstration of antibiotic mixture, were found not to be anenic. This technique, as compared with methods of surgical delivery of axenic young, embodies a number of advantages. It is harmless to the mother and to the newborn, it is relatively inexpensive, and it obviates the risk of prematurity involved in elective surgical delivery before term.

Administration, Oral↗

Selective decontamination of the digestive tract attenuated the myocardial inflammation and dysfunction that occur with burn injury.

This study examined the effects of oral antibiotics to selectively decontaminate the digestive tract (SDD) on postburn myocardial signaling, inflammation, and function. We hypothesized that antibiotic therapy to eliminate pathogens from the gastrointestinal (GI) tract would reduce myocardial inflammatory responses and improve postburn myocardial performance. Sprague-Dawley rats received polymyxin E (15 mg), tobramycin (6 mg), and 5-flucytosin (100 mg) by oral gavage twice daily for 3 days preburn and 24 h postburn. Experimental groups included 1) sham burn given vehicle (3 ml water), 2) sham plus SDD, 3) burn over 40% total body surface area (TBSA) plus SDD, and 4) burn over 40% TBSA given vehicle. All burns received lactated Ringer solution (4 mg.kg(-1).%burn(-1)); myocardial signaling (PKCepsilon/p38 MAPK/NF-kappaB) was studied 2, 4, and 24 h postburn; and cytokine secretion (systemic and myocyte secreted cytokines, ELISA) and cardiac function were examined 24 h postburn. Vehicle-treated burn injury increased myocardial PKCepsilon/p38 MAPK expression, promoted NF-kappaB nuclear translocation, promoted TNF-alpha, IL-1beta, IL-6, and IL-10 secretion, and impaired myocardial function. SDD attenuated burn-related proinflammatory myocardial signaling, cytokine secretion, and myocardial contractile defects. Our data suggest that burn-related loss of GI barrier function and translocation of microbial products serve as upstream mediators of postburn myocardial inflammatory signaling and dysfunction.

Animals↗

Prognostic significance of NOD2/CARD15 variants in HLA-identical sibling hematopoietic stem cell transplantation: effect on long-term outcome is confirmed in 2 independent cohorts and may be modulated by the type of gastrointestinal decontamination.

To assess the role of NOD2/CARD15 variants on the long-term outcome of allogeneic stem cell transplantation in a genetically homogeneous group, we extended our previous study (cohort I, n = 78) and typed DNA for NOD2/CARD15 single nucleotide polymorphisms (SNPs) from an additional 225 recipients and their HLA-identical sibling donors (cohort II) treated at four other European centers. Results of genotyping were compared with clinical outcome. The strong association of NOD2/CARD15 variants with transplantation-related mortality (TRM) was confirmed in univariate and multivariate analysis; TRM increased from 20% in cohort I/22% in cohort II in recipient/donor pairs without any NOD2/CARD15 variants to 47% in cohort I/32% in cohort II in the presence of one variant in either donor or recipient and further to 57% in cohort I/74% in cohort II in the presence of 2 or more variants (P < .002 in both cohorts). NOD2/CARD15 SNPs were not associated with relapse rate but had a strong impact on overall survival. In an analysis of center effects, the type of gastrointestinal decontamination was the only factor interfering with the prognostic significance of NOD2/CARD15 SNPs. Our data further support an interaction between gastrointestinal defense mechanisms, activation of the innate immune system, and specific transplant-related complications.

Adolescent↗

Prevention of MRSA pneumonia by oral vancomycin decontamination: a randomised trial.

This study was undertaken to assess whether oropharyngeal vancomycin may control oropharyngeal carriage and lower airway infection due to methicillin-resistant Staphylococcus aureus (MRSA) acquired in the intensive care unit (ICU). Secondary endpoints were the emergence of vancomycin-resistant enterococci, vancomycin-intermediate S. aureus and vancomycin consumption. A total of 84 patients, admitted to a medical/surgical ICU and mechanically ventilated for >72 h, were randomly assigned to control (n=42) or test (n=42) group. Both groups received the protocol of selective decontamination of the digestive tract, including polymyxin E, tobramycin and amphotericin B. Patients in the test group received 0.5 g of a 4% vancomycin gel at 6-h intervals in the oropharynx. Lower airway infections due to MRSA acquired on the ICU were reduced in the test group, as was oropharyngeal carriage. Neither vancomycin-resistant enterococci nor vancomycin-intermediate S. aureus were isolated from either surveillance or diagnostic samples during the study period. The vancomycin costs were lower in the test group. This study demonstrates that oropharyngeal vancomycin, which controls intensive care unit-acquired lower airway infections and secondary carriage due to methicillin-resistant Staphylococcus aureus, is cost-effective and safe in terms of vancomycin-resistant enterococci and vancomycin-intermediate Staphylococcus aureus.

Administration, Oral↗

External decontamination of wild leeches with hypochloric acid.

BACKGROUND: Medicinal leech, Hirudo medicinalis, has been used in plastic and reconstructive surgery, to relieve venous congestion and to improve the microrevascularization of flaps. In many countries, wild leeches are still provided from local markets and utilised with antibiotic prophylaxies. In this research, results of identification of bacteria in the transport fluid is reported, oral and intestinal floras and the antibiograms of the identified microorganisms are investigated. Also, to avoid possible infections, the ability of hypochloric acid, a disinfectant, to suppress the relevant microorganisms without changing the life style and behavior of leeches in terms of sucking function, is investigated. METHODS: Bacterial identifications and antibiograms of oral and intestinal flora and transport medium were performed for 10 leeches. The optimum concentration of hypochloric acid which eliminated microorganisms without affecting the viability and sucking function of the leeches were determined by dilution of hypochloric acid to 100, 50, 25, 12.5, 6.25 ppm concentrations in different groups of 25 leeches. Finally, 20 leeches were applied atraumatically to the bleeding areas of rats, the duration of suction was determined and compared statistically between the leeches treated and not treated with hypochloric acid solution. RESULTS: Aeromonas hydrophilia was the most commonly identified microorganism and found to be resistant to first generation cephalosporins, frequently used in prophylaxis at surgical wards. In the next stages of the study, the leeches were subjected to a series of diluted hypochloric acid solutions. Although disinfection of the transport material and suppression of the oral flora of hirudo medicinalis were successful in 100, 50, 25, 12.5, 6.25 ppm concentrations; 12.5 ppm solution was the greatest concentration in which hirudo medicinalis could survive and sucking function was not affected significantly. CONCLUSIONS: External decontamination of wild leeches with 12.5 ppm hypochloric acid enables bacterial suppression without causing negative effects on leech sucking function and life.

Aeromonas↗

Opinion: the clinical use of selective digestive decontamination.

Several recent meta-analyses have shown that the use of SDD can reduce the occurrence of nosocomial pneumonia among ventilated patients in the intensive care unit (ICU) setting. However, the use of SDD has also been demonstrated to increase subsequent patient colonization and infection with antibiotic-resistant bacteria, particularly Gram-positive cocci. Therefore, the routine use of SDD cannot be advocated at the present time. The mortality benefit of SDD appears to occur in surgical/trauma patients, and to be associated primarily with the administration of parenteral antibiotics. This is already an accepted practice in most patients during the perioperative period (eg prophylactic parenteral antibiotics for 24 h). Prolonged decontamination of the aerodigestive tract with topical antimicrobials does not appear to influence outcome, and should not be routinely employed.

Anti-Bacterial Agents↗

Gas chromatography/mass spectrometric analysis of N,N-dialkylaminoethyl-2-methoxyethyl ethers as the decontamination markers of N,N-dialkylaminoethyl-2-chlorides for verification of the Chemical Weapons Convention.

The detection and identification of markers of scheduled chemicals plays an important role in verification analysis of Chemical Weapons Convention (CWC). This paper describes the gas chromatography electron ionization mass spectrometric (GC/EI-MS) analysis of N,N-dialkylaminoethyl-2-methoxyethyl ethers (DAEMEs), which are identified as characteristic degradation markers of N,N-dialkylaminoethyl-2-chlorides. N,N-dialkylaminoethyl-2-chlorides produced DAEMEs on reacting with the universally used decontamination solution (DS-2). DAEMEs were prepared by condensation of N,N-dialkylaminoethyl-2-chlorides with 2-methoxy ethanol the active ingredient of DS-2. Based on the GC/EI-MS analysis of DAEMEs the generalized fragmentation routes are proposed which rationalize most of the characteristic ions in EI-MS.

Journal Article↗

Closure of a tracheoesophageal fistula by bronchoscopic application of fibrin glue and decontamination of the oral cavity.

A tracheoesophageal fistula was successfully closed with a fibrin adhesive applied by means of a fiberoptic bronchoscope, instead of by esophagoscopy. To facilitate closure of the fistula, the technique was combined with decontamination of the oral cavity, to avoid bacterial contamination. The procedure is proposed as an alternative to surgery for critically ill patients.

Administration, Topical↗

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.

Anti-Bacterial Agents↗

Selective decontamination of the digestive tract in multiple trauma patients. A prospective double-blind, randomized, placebo-controlled study.

STUDY OBJECTIVE: The aims of the study were to evaluate the technique of selective digestion decontamination (SDD) in preventing the development of nosocomial infections in a selected population and to assess the effects on colonization of the oropharynx, nares, and bronchi. A financial assessment was also performed. DESIGN: Prospective, double-blind, randomized placebo-controlled trial using amphotericin B, colistin sulfate (polymixin E), and gentamicin applied to the nares, the oropharynx, and enterally; no parenteral antibiotics were given during the study period. The SDD was applied every 6 h during the study period. SETTING: Multidisciplinary ICU in a university hospital. PATIENTS: A total of 148 trauma patients admitted emergently and intubated within less than 24 h were enrolled. Seventy-two patients who received placebo and 76 treated patients were analyzed on an "intention-to-treat" basis. INTERVENTIONS: Microbiologic surveillance samples of oropharyngeal and bronchial secretions, urine, and any other potentially infected sites were taken at the time of ICU admission and twice weekly thereafter until discharge from the unit. MEASUREMENTS AND RESULTS: With the use of SDD, colonization was significantly reduced in the oropharynx and nares (<0.05) but not in bronchi. However, episodes of bronchopneumonia were significantly reduced (19 in the active group vs 37 in the placebo group; p,0.01). Staphylococcus aureus remained the main potential pathogen causing bronchial colonization and subsequent bronchopneumonia. There was no reduction in the incidence of other infections. Days in the ICU, duration of mechanical ventilation, and mortality rate were unchanged. After the use of SDD, Gram-positive colonization tended to increase and this was mainly due to methicillin-resistant coagulase-negative staphylococci. The total cost of antibiotic therapy ($62,117 [US] in the placebo group and $36,008 in the SDD group) was decreased by 42% with the use of SDD. Clinically important complications of SDD were not encountered. CONCLUSIONS: The use of SDD in this population of trauma patients reduced the incidence of bronchopneumonia and the total charge for antibiotics. Stay in the ICU, mechanical ventilation, and mortality rate were unchanged. Methicillin-resistant coagulase-negative staphylococci were selected by SDD in some patients and the clinical relevance of this colonization needs further evaluation.

Amphotericin B↗

In vivo and in vitro evaluation of the efficacy of a peracetic acid-based disinfectant for decontamination of acrylic resins.

The purpose of this study was to assess the antimicrobial efficacy of a peracetic acid-based disinfectant for decontamination of heat-polymerized, chemically activated and microwave-polymerized acrylic resins. Resin plates were contaminated in vivo upon intraoral use by 10 volunteers for 7 nights and slabs were contaminated in vitro by contact with Bacillus subtilis and Bacillus stearothermophilus. The contaminated acrylic resin specimens were immersed in a 0.2% peracetic acid-based disinfectant (Sterilife; Lifemed) for 5 min or 10 min and placed in a BHI culture medium. After incubation at 37 degrees C for 48 h, bacterial growth was assessed by analyzing turbidity of the medium. For all types of acrylic resin, no turbidity of the medium was observed for any of the resin specimens immersed in the peracetic acid-based disinfectant for either 5 or 10 min. On the other hand, the media with specimens that were not immersed in the disinfectant (control) showed turbidity in 100% of the cases, indicating the presence of microorganisms in both tested conditions. In conclusion, immersion for at least 5 min in a 0.2% peracetic acid-based disinfectant promoted high-level disinfection of heat-polymerized, chemically activated and microwave-polymerized acrylic resins contaminated with either human saliva or Bacillus subtilis or Bacillus stearothermophilus.

Acrylic Resins↗

Formation and decontamination of biofilms in dental unit waterlines.

BACKGROUND: Biofilms are a natural occurrence in aquatic environments, including community drinking water systems. The interior of small-diameter tubings in dental unit waterlines (DUWL) are also sites of biofilm formation. In the lumen of the tubings, the flow is minimal, and the water becomes stagnant when the units are not in use. Molecules precipitate from the water onto the interior wall and promote the adherence of planktonic microorganisms from the water. Once they become sessile, the microorganisms change their phenotype. After adherence, there is a so-called surface-associated lag time, and the organisms then enter a growth phase and produce exopolysaccharides that coat the organisms in a slime layer. Within the biofilm, the microorganisms can signal one another, transfer nutrients, and exchange genetic material. The insoluble exopolysaccharides shield the microorganisms from displacement and from penetration by predator organisms, antibiotics, and disinfectants. The external surface layer of microorganisms is faster growing and may detach as "swarmer" cells. Detachment of microorganisms from dental unit biofilm flushed into the oral cavity could theoretically infect the patient. Splatter and aerosols from dental procedures may possibly infect health care personnel. METHODS: This study compared three DUWL cleaners (an alkaline peroxide product, a freshly mixed chlorine dioxide product, and a buffer-stabilized chlorine dioxide product) in 16 dental units with self-contained water systems, 6 months after installation in a periodontal teaching clinic. One unit treated by flushing and drying served as a control. Units were sampled daily for 10 days with heterotrophic plate count (HPC) sampler plates. The plates were incubated for 7 days at room temperature, and colonies were counted at 10.5x magnification. Samples of internal water tubing before and after the use of waterline cleaners were processed and examined by scanning electron microscopy. RESULTS: The estimated mean HPC was derived from original and replicate independent counts of two investigators of undiluted and diluted samples, reported as colony forming units (CFU)/ml. Shock treatments with the alkaline peroxide product (n = 5) reduced the HPC from baseline, but in the ratio of daily counts to control, there was a large variance and a trend to return of high counts as days passed. The mean daily HPC was significantly better than the control for only 3 of the 9 days of treatment and exceeded the goal of 200 on 3 days. Freshly mixed chlorine dioxide (n = 4) and the buffer-stabilized chlorine dioxide (n = 5) both reduced HPC to near 0 on all days. Their ratios of daily estimated means to that of the control were significantly (P < 0.001) better at all times. In comparing treatments, the freshly mixed chlorine dioxide was better (P < 0.001) than the alkaline peroxide on 8 of 9 days. The buffered chlorine dioxide treatment was better than the alkaline peroxide at all times. The two chlorine dioxide treatments each had so many HPC counts of 0 that a meaningful statistical difference between them was not calculated. Scanning electron microscopy of plastic waterline tubing samples taken before and after treatments showed reductions in biofilm coverage, but the differences were not statistically significant. CONCLUSIONS: Chlorine dioxide waterline cleaners are effective in decontaminating DUWL biofilm. Chlorine dioxide has advantages over other chlorine products. Controlling DUWL biofilm may have beneficial effects on nosocomial infections.

Alkalies↗