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PubMed1981

Endemic rate of fluid contamination and related septicemia in arterial pressure monitoring.

Contamination of the fluid within intra-arterial infusions used for hemodynamic monitoring has produced epidemic bacteremias, but little data exist on endemic rates of contamination and related septicemia. We prospectively studied 102 intra-arterial infusions used in 56 high-risk patients who required prolonged monitoring. During the study, administration sets were changed every 48 hours, but transducer chamber-domes and continuous flow devices were used until the intra-arterial infusion was discontinued. Cultures were obtained from the transducer-transducer chamber-dome interface and of fluid in the transducer chamber-dome of the 102 intra-arterial infusions; 12 (11.8 percent) showed contamination of transducer chamber-dome fluid, in 8 cases (7.8 percent) associated with concordant bacteremia. In each bacteremia, transducer chamber-dome fluid contained 1 to greater than 10(5) (median, 10(4)) cfu/ml. Four bacteremias are considered definitely related and four, possibly related, to the intra-arterial infusion. In all 12 contaminated intra-arterial infusions and with all eight bacteremias, the transducer chamber-dome had been used for more than two days (P = 0.006). No concordant contamination of transducer-transducer chamber-dome interfaces was identified. (1) Intra-arterial infusions for pressure monitoring cause sporadic septicemias endemically. (2) With prolonged monitoring, transducer chamber-domes and continuous flow devices should be replaced at periodic intervals, ideally with the administration set, every 48 hours; since implementing this policy, only three contaminated intra-arterial infusions and no related septicemias have been detected in 53 intra-arterial infusions monitored over our months (P = 0.02).

Adult↗

PubMed1991

Nosocomial infections from contaminated endoscopes: a flawed automated endoscope washer. An investigation using molecular epidemiology.

Approximately 1 year after purchase of one manufacturer's automated endoscope washing machine, we began to detect heavy contamination of upper gastrointestinal (UGI) endoscopes cultured after cleaning and disinfection in the washer. During the first 6 months of 1988, 77% of surveillance cultures (20-mL flush through the biopsy channel) were positive for gram-negative bacilli (median concentration, 10(5) cfu/mL), most frequently Pseudomonas aeruginosa serotype 10. During the first 19 months of use of the washer, nosocomial post-UGI endoscopy colonization or infections with P. aeruginosa increased 36%. Investigations show that endoscope contamination derives from a flaw in the design of the EW-10 washer: the detergent holding tank, inlet water hose, and air vents cannot be reliably disinfected and contain heavy biofilms that recontaminate the machine after it has been disinfected, as specified by the manufacturer, with glutaraldehyde. Only by rinsing machine-cleansed endoscopes with 70% alcohol followed by forced air drying has reliable disinfection been achieved. Since adaptation of terminal alcohol treatment and drying, post-UGI endoscopy colonization or infection by P. aeruginosa has declined threefold (p less than 0.001). Testing in other centers using the manufacturer's EW-10 or EW-20 washer has shown similar contamination. In three centers, including our own, postendoscopy infections by machine-associated type 10 P. aeruginosa have been confirmed by demonstrating concordance between isolates from contaminated machines or endoscopes and from infected patients by immunoblot of whole cell lysates and by pulsed-field electrophoresis of DraI endonuclease-digested genomic DNA. This problem reaffirms the vulnerability to microbial contamination of water-containing apparatus and equipment in patient care and points up the critical importance of engineering design to prevent contamination.

Cross Infection↗

PubMed1996

Peptic-tryptic digests of gliadin: contaminating trypsin but not pepsin interferes with gastrointestinal protein binding characteristics.

For many years, peptic-tryptic digests of gliadin, known as Frazer's fraction III, have been used in investigations of gliadin effects. Potential contamination by the proteases pepsin and trypsin, however, was not considered. To investigate the influence of contaminating proteases on binding of gliadin peptides to rat small intestinal brush border membranes we compared binding characteristics of different gliadin digests. Binding of biotinylated probes was studied in dot blots and Western blots with an enhanced chemiluminescence system. In gliadin peptide preparations only contaminating trypsin, but not pepsin, was detectable by specific antisera. Digestion with insoluble proteases attached to cross-linked beaded agarose yielded gliadin peptides free of contaminating pepsin and trypsin. These peptides bound 30% less to brush border membranes. Using these peptides, there was no trypsin-typical binding pattern to low molecular mass membrane proteins in contrast to peptide preparations which contained contaminating trypsin. In conclusion contaminating trypsin might alter gliadin peptide binding characteristics by direct binding to brush border membranes and by interfering with interactions between gliadin peptides and brush border membranes.

Animals↗

PubMed1988

Enzyme-linked immunosorbent assays (ELISAs) for the determination of contaminants resulting from the immunoaffinity purification of recombinant proteins.

Two immunoassays have been developed for the quantitation of part-per-million levels of contaminants likely to co-purify with monoclonal antibodies produced in tissue culture and purified by protein A affinity chromatography. These contaminants are bovine IgG originating from the fetal bovine serum used in cell culture, and protein A. Mouse IgG was shown not to interfere in the bovine IgG assay, where contamination levels of 0.2-0.7% bovine IgG were measured in the lots of monoclonal antibody tested. The protein A ELISA was developed with monoclonal antibody included in the standard, and in the preparations of monoclonal antibody tested, 64 parts per million (ppm) or less of protein A were demonstrated. An additional immunoassay was developed to quantitate monoclonal antibody contamination of two recombinant proteins, rHBsAg and rgp 120 from HIV, purified by affinity chromatography with such antibodies. Possible interference of monoclonal antibody quantitation by the respective antigens was examined in this ELISA, and contamination levels of less than 56 ppm of antibody were determined in the purified recombinant proteins. The three immunoassays were shown to be specific for the major protein contaminants in either monoclonal antibodies or the recombinant proteins and were necessary in demonstrating their purity.

Animals↗

PubMed1990

Bacterial adherence and contamination during radiographic processing.

Oral fluids are potential contaminants of radiographic processors. This investigation measured bacterial contamination in a radiographic processing room during times of high and low clinical activity and processing effects on five types of microorganisms. Cultures in the clinical setting, during high and low activity, were taken by brain-heart infusion agar plates placed near automatic processors. Site samples were taken of entrance, developer, fixer, water, and exit surfaces. Measurements of processing effects were accomplished by intentional contamination of films run in series through an automatic processor. Site samples were again taken of the processor. In the clinical setting colony-forming units increased with activity. Radiographic processing after intentional contamination decreased colony-forming units on films, but they increased for all processing solutions. Bacteria on radiographic film survived processing. Although processing procedures significantly reduce the number of bacteria on films, the potential for contamination and cross-contamination remains.

Air Microbiology↗

PubMed1983

Effects of long-term feeding of ammoniated, aflatoxin-contaminated corn to Fischer 344 rats.

The effectiveness of ammonia treatment in reducing the chronic toxicity of aflatoxin-contaminated corn was determined. Fischer 344 rats were fed semi-purified rations containing 20% w/w corn that was either free of aflatoxin or naturally contaminated with 880 micrograms/kg total aflatoxin and was either treated with ammonia gas or was not treated. Therefore the rats that were fed the aflatoxin-contaminated diet received 176 ppb total aflatoxins. Body weight and food consumption were recorded throughout the study; hematological measurements were made after 87 weeks of feeding; and after 91 weeks the rats were killed and histopathological abnormalities were noted. Signs of chronic toxicosis in rats fed aflatoxin-contaminated corn included increased mortality, decreased hematocrit and hemoglobin levels, elevated serum alkaline phosphatase activities, and a 100% incidence of liver neoplasia. These signs did not occur in rats in the other dietary treatment groups, including those fed ammoniated, aflatoxin-contaminated corn. The results provide further evidence that the atmospheric ammoniation process effectively reduces the toxicity of aflatoxin-contaminated corn.

Aflatoxins↗

PubMed1975

Environmental and food contamination with PCB's in Japan.

In Japan "yusho", i.e., poisoning caused by ingestion of rice oil contaminated with PCB's, broke out in October 1968, and produced more than 1200 officially certified cases. Nevertheless, it was only regarded as a kind of food poisoning and its connection with environmental and biological contamination was only imperfectly taken into consideration. Finally, in the autumn of 1970, two study groups, from the Ehime University and the Kyoto City Hygienic Institute, reported on the PCB contamination of salt water and fresh water fishes in Japan. Subsequently many reports about PCB's as an environmental contaminant have been published by several study groups throughout Japan, and nowadays the PCB polluted state of Japan has become rather clearly recognized. This report will present information on environmental, food and human contamination with PCB's in Japan especially also in some typically contaminated local areas, in addition to summarizing some overall aspects of the PCB problem in Japan (e.g., the production, shipment and use of PCB's).

Adipose Tissue↗

PubMed1994

The fate of environmental contaminants in the food chain.

This paper reviews the major sources of industrial environmental pollutants that may give rise to organic contaminants in foods, indicates which foods tend to be most frequently found to be contaminated and summarises available data on levels of occurrence. Polycyclic aromatic hydrocarbons (PAHs), phthalic acid esters, polychlorinated dibenzodioxins and dibenzofurans (PCDDs and PCDFs), polychlorinated biphenyls (PCBs) and organic phosphates are widespread environmental contaminants which have all been detected in foods. Estimates of exposure to these contaminants from total diet and other studies are summarised. Some pollutants such as volatile halocarbons and benzene tend to only occur as localised contaminants for which targeted monitoring of foods is necessary. The most difficult area is regarded as the detection of previously unrecognised contaminants in foods for which some possible approaches are described.

Environmental Pollutants↗

PubMed1992

Bacterial contamination of enteral feeds as a possible risk of nosocomial infection.

The degree of microbiological contamination in enteral diets was studied and the possible infectious complications that could arise in the patient after administration of an enteral feed were evaluated. Of the 208 diets studied, 56 (26.9%) were contaminated and 152 (73.1%) were sterile. Of the 56 contaminated diets, 11 could be used as delivered, but the other 45 required further modification. Of the patients who had received enteral feeding, 43 developed gastrointestinal symptoms in the first 24 h (fever, vomiting, abdominal pain and diarrhoea). Twenty-nine (67.4%) had received a contaminated diet and 14 (32.6%) an uncontaminated one. We conclude that contamination of enteral feeds may constitute a risk factor for nosocomial infection, and consider it necessary to carry out epidemiological surveillance in order to control the factors which may lead to contamination of enteral diets.

Cross Infection↗

PubMed1992

Bacterial contamination and the effect of filters in anaesthetic circuits in a simulated patient model.

In order to investigate bacterial contamination of anaesthetic breathing circuits and means of prevention of this, six different laboratory experiments were performed. These experiments involved the bacterial contamination of Dräger Narkose Spiromat 650 and Dräger AV-1 circle system circuits and of an isolated soda lime carbon dioxide absorber. The effects of anaesthetic gas, gas flow rate and the incorporation of a hydrophobic membrane heat and moisture exchanging bacterial/viral filter (HMEF) at the patient end of these circuits were investigated. It was found that without a HMEF the whole interior of the anaesthetic circuits became contaminated with bacteria. Components closest to the simulated patient showed the highest levels of contamination. Higher gas flows were associated with decreased levels of circuit contamination, presumably because more bacteria were expelled from the system. Halothane (1 volume %) and soda lime were not found to have any demonstrable bactericidal action. The presence of a HMEF between the simulated patient and the Y-piece prevented any detectable contamination from reaching the circuit. Consequently, the presence of a HMEF provides protection of the anaesthetic circuit as well as other patients, healthcare workers and the environment.

Anesthesia, Closed-Circuit↗

PubMed1994

Dispensing surgical gloves onto the open surgical gown pack does not increase the bacterial contamination rate.

In implant surgery air and surface contamination have become important factors in post-operative wound infection. We established the rate of contamination of surgical gown packs and found that dropping gloves onto the open gown pack prior to scrubbing had no effect on it. Ninety-six contact plates were used for this study, which was carried out during clean orthopaedic operations in one operating room. The overall rate of contamination was 65%. Most of the contaminants were skin commensals. The rate of contamination was 67% when gloves were dropped onto the gown pack compared with 63% when opened and presented to the scrubbed and gowned theatre staff. However this difference was statistically not significant. The high rate of contamination was probably due to the gown packs having been left opened for too long. This delay arose because each gown pack had three gowns and would have been avoided if single gown packs had been used.

Environmental Microbiology↗

PubMed1995

Automation of polymerase chain reaction tests. Reduction of human errors leading to contamination.

We compared the performance over 21 months of manually performed polymerase chain reaction (PCR)-based DNA analysis experiments with 25 months of automated PCR performed by a Zymark robotic system. Automation of the PCR technique resulted in a sixfold reduction in the number of experiments reporting carryover contamination and decreased the overall rate of contamination among total reactions 68-fold. Whereas contamination occurrences among manual experiments were evenly dispersed over the study interval and correlated with the lack of experience of laboratory personnel, the contamination that occurred with the robotic system was confined to the first 10 months of operation. In manual experiments, many of the 81 no-target false positives were sufficiently strong to result in the invalidation of 151 samples and positive controls. The seven no-target control false positives in the automated system were weak bands that were easily subtracted as background. Because none of the negative samples had DNA bands, no sample on the automated system has ever been invalidated as a result of contamination. Automation of PCR tests appears to offer great promise in reducing contamination to acceptable levels (e.g., < or = 0.1%).

DNA↗

PubMed2004

Bacterial contamination of multiple-dose vials: a prevalence study.

BACKGROUND: Two patients died of a meningitis caused by Pseudomonas aeruginosa in a hospital in Germany in July 2001, their infections having been caused by a contaminated contrast media (iomeprol [Imeron]) used as a multiple-dose vial (MDV) over 8 days. Therefore, a prevalence study was performed to investigate the use and contamination of multiple-use vials in a tertiary hospital. METHODS: In a 1300-bed hospital on a specific day in November 2001, all used MDVs were collected by the infection control nurses. Information was recorded about the medication, labeling of vials, storing temperature, wards, and dates of opening. Each vial was also tested for sterility. RESULTS: Opened vials were to be found in all wards. Of the 227 vials available, 1 vial and 1 spike were contaminated with Staphylococcus epidermidis (contamination rate 0.9%; 95% CI, 0.3-2.1). The opening dates were marked on only 114 (50%) MDVs, 15 (13%) of which had already expired. Only 44 (19%) MDVs had been stored in the refrigerator, whereas 109 MDVs contained medications without any preserving agent. CONCLUSION: Results revealed somewhat risky handling of MDVs. In light of a possible high risk in this hospital of about 1 contaminated MDV per day, and in view of many reported outbreaks induced by contaminated MDVs, the following infection control measures were encouraged: alcohol hand hygiene, the disinfection of gums, observance of the manufacturer's recommendations, appropriate storing temperatures, marking the opening time, and avoiding the multiple use of medications not containing preserving agents.

Bacterial Infections↗

PubMed2007

Chemical contaminants in fish feeds used in federal salmonid hatcheries in the USA.

Recent studies have demonstrated that fish feeds contain significant concentrations of contaminants, many of which can bioaccumulate and bioconcentrate in fish. Organochlorine (OC) contaminants are present in the fish oils and fish meals used in feed manufacture, and some researchers speculate that all fish feeds contain measurable levels of some contaminants. To determine the concentration of contaminants in feeds used in US Fish and Wildlife Service's National Fish Hatcheries, we systematically collected samples of feed from 11 cold-water fish hatcheries. All samples (collected from October 2001 to October 2003) contained at least one polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), polychlorinated biphenyl (PCB) congener, or dichlorodiphenyltrichloroethane (DDT) metabolite. Of the 55 samples in which they were analyzed 39 contained PCDDs, 24 contained PCDFs and 24 contained DDT or its metabolites. There were 10- to 150-fold differences in concentrations of total PCBs, PCDDs, PCDFs and DDT. Although PCBs were the most commonly detected contaminant in our study, concentrations (range: 0.07-10.46 ng g(-1) wet weight) were low compared to those reported previously. In general, we also found lower levels of OCs than reported previously in fish feed. Perhaps most notable was the near absence of OC pesticides - except for DDT or its metabolites, and two samples containing hexachlorocyclohexane (HCH). While contaminant concentrations were generally low, the ecological impacts can not be determined without a measure of the bioaccumulation of these compounds in the fish and the fate of these compounds after the fish are released.

Animal Feed↗

PubMed2005

The use of variable-number tandem-repeat mycobacterial interspersed repetitive unit typing to identify laboratory cross-contamination with Mycobacterium tuberculosis.

A retrospective study including 515 Mycobacterium tuberculosis isolates from 215 patients was conducted to investigate possible laboratory contamination with M. tuberculosis over a 1-year period in a university hospital. All cultures underwent variable-number tandem-repeat (VNTR) typing. Cultures suspected of being contaminated in the VNTR analysis and possible sources of contamination underwent mycobacterial interspersed repetitive unit (MIRU) typing further. Overall, 8 (3.7%) cases of 215 patients were considered possible false-positives. Five (2.3%) cultures might be contaminated during initial batching processing, and 1 (0.5%) and 4 (1.9%) cultures of them were further classified as presumed and possible cases, respectively, of cross-contamination on clinical grounds. Three (1.4%) cultures might be contaminated by cultures that had been processed in species identification procedures in the same laminar-flow hood. The 2-step strategy using VNTR and MIRU analyses in combination in this study appears to be a valuable means for the study of false-positive cultures.

Bacterial Typing Techniques↗

PubMed2005

Exposure to metal mixtures and human health impacts in a contaminated area in Nanning, China.

Cadmium and lead have been identified as very toxic metals, which are widely present in the environment due to natural and anthropogenic emissions. Many studies have shown that the food chain is the main pathway of cadmium and lead transfer from the environment to humans. It is well documented that many factors will affect their transfer through food chains. Previous investigations on heavy metals were mostly concentrated on one contaminant in isolation. However, in real environments, exposure to mixtures of metals is ubiquitous such that cadmium pollution is invariably being associated with lead and zinc, etc. This study focuses on the contamination and health effects of the metal mixtures. For this purpose, a dietary survey was taken for 3 groups in Nanning in October 2002. Samples of soils, plants (vegetables), urine and blood of humans were measured for Cd, Fe, Cu, Zn, Ca and Pb, in addition, the urinary indicators of renal dysfunction Albumin (ALB), N-acetyl-beta-D-glucosaminidase (NAG), Beta-2-microglobulin (beta2-MG) and Retinol-binding protein (RBP) in urine were also measured. Results showed that soil contamination with metal mixtures had caused significant renal dysfunction of the local residents living in the contaminated area, and the dose-response curve was somewhat altered by the mixed contamination of Cd and Pb as well as the intake of other minerals. The importance of mixtures of metal contamination and human health are also discussed in this paper.

Acetylglucosaminidase↗

PubMed2005

Impacts of sewage irrigation on heavy metal distribution and contamination in Beijing, China.

A potential hazard to Beijing was revealed due to the accumulation trend of heavy metals in agricultural soils with sewage irrigation, which results in metal contamination and human exposure risk. Samples including soils and plants were collected to assess the impacts of sewage irrigation on the irrigated farming area of Beijing. Concentrations of the five elements Cd, Cr, Cu, Zn, and Pb were determined in samples to calculate the accumulation factor and to establish a basis for environmental protection and the suitability of sewage irrigation for particular land use in the urban-rural interaction area of Beijing. Using reference values provided by the Beijing Background Research Cooperative Group in the 1970s, the pollution load index (PLI), enrichment factor (EF), and contamination factor (CF) of these metals were calculated. The pollution load indices (sewage irrigation land 3.49) of soils indicated that metal contamination occurred in these sites. The metal enrichment (EF of Cd 1.8, Cr 1.7, Cu 2.3, Zn 2.0, Pb 1.9) and the metal contamination (CF of Cd 2.6, Cr 1.5, Cu 2.0, Zn 1.7, Pb 1.6) showed that the accumulation trend of the five toxic metals increased during the sewage irrigation as compared with the lower reference values than other region in China and world average, and that pollution with Cd, Cu, Zn, and Pb was exacerbated in soils. The distributions of these metals were homogeneous in the irrigation area, but small-scale heterogeneous spatial distribution was observed. Irrigation sources were found to affect heavy metal distributions in soils. It was suggested that heavy metal transfer from soils to plants was a key pathway to human health exposure to metal contamination. However, with the expansion of urban areas in Beijing, soil inhalation and ingestion may become important pathways of human exposure to metal contamination.

Agriculture↗

PubMed2006

Efficiency of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing gloves.

Food processing gloves are typically used to prevent cross-contamination during food preparation. However, gloves can be contaminated with microorganisms and become a source of contamination. This study investigated the survival of Listeria monocytogenes on gloves and determined the efficacy of electrolyzed oxidizing (EO) water for reducing L. monocytogenes contamination on seafood processing gloves. Three types of reusable gloves (natural rubber latex, natural latex, and nitrile) and two types of disposable gloves (latex and nitrile) were cut into small pieces (4 x 4 cm(2)) and inoculated with 5-strain L. monocytogenes cocktail (5.1 x 10(7) CFU/cm(2)) with and without shrimp meat residue attached to surfaces. L. monocytogenes did not survive well on clean reusable gloves and its populations decreased rapidly to non-detectable levels within 30 min at room temperature. However, high levels of Listeria cells were recovered from clean disposable gloves after 30 min of inoculation. Presence of shrimp meat residue on gloves enhanced the survival of L. monocytogenes. Cells of L. monocytogenes were detected on both reusable and disposal gloves even after 2 h at room temperature. Soaking inoculated gloves in EO water at room temperature for 5 min completely eliminated L. monocytogenes on clean gloves (>4.46 log CFU/cm(2) reductions) and significantly (p<0.05) reduced the contamination on soil-containing gloves when compared with tap water treatment. EO water could be used as a sanitizer to reduce L. monocytogenes contamination on gloves and reduce the possibility of transferring L. monocytogenes from gloves to RTE seafoods.

Colony Count, Microbial↗