Cot mattresses as reservoirs of potentially harmful bacteria and the sudden infant death syndrome

Cot mattress materials were investigated as potential reservoirs of bacteria in relation to the sudden infant death syndrome (SIDS). The sleeping position of the infant significantly influenced bacterial population density of cot mattress polyurethane foams (p<0.0000001) and their covers (p<0.004). Staphylococcus aureus was isolated at significantly higher frequency (p<0.03) from the infant's head region of cot mattress materials. Significantly higher bacterial population densities (p<0.001) were associated with polyurethane foams from non-integral mattresses (exposed polyurethane foam), when compared to those from mattresses completely covered by polyvinyl chloride (integral type mattress). The frequency of isolation of S. aureus from polyurethane foams from non-integral mattresses was also significantly higher (p=0.03) than from foams from the integral type. The following factors were significantly associated with increased frequency of isolation of S. aureus: from the polyurethane foam, previous use of non-integral mattresses by another child (p=0.03 for all sample sites, p=0.01 for torso region); from the covers, sleeping in the prone position (p=0.003 head region, p=0.001 torso region). Prone sleeping was also significantly associated with increased bacterial population levels (p=0.01) and increased frequency of isolation of Escherichia coli (p=0.02) from the torso region of cot mattress covers. These findings could explain some recently identified risk factors for SIDS associated with type and previous use of cot mattresses. Clostridium perfringens was isolated at very low frequency and Streptococcus pyogenes was not isolated from any cot mattress materials tested.     

Growth and survival of bacteria implicated in sudden infant death syndrome on cot mattress materials

AIMS: To compare growth and survival of selected bacteria implicated in sudden infant death syndrome (SIDS) on cot mattress polyurethane (PU) inner-foams and on different types of cot mattress cover materials. METHODS AND RESULTS: Escherichia coli, Staphylococcus aureus or Streptococcus pyogenes were inoculated onto swatches of new-unused cot mattress PU inner-foam and onto three types of cot mattress covers (polyvinyl chloride, cotton and polyester). The influence of inoculation cell density, relative humidity (RH) and temperature of incubation on survival was assessed by recovery of cells in 0.85% NaCl, with viable cell enumeration by plate counting on selective and differential media. Utilization of carbon and nitrogen sources within cot mattress PU was assessed by following growth on aqueous leachate from PU, and by colorimetric determination of aromatic amines. Good survival capability (>206 d) was shown by all three test species on PU inner-foam and on polyester mattress cover at high RH (75%), but only by Staph. aureus on PU at low RH (25%). Aqueous soluble material from PU foam supports bacterial growth; removal of aromatic amines from aqueous leachate from PU accompanies growth of Staph. aureus. CONCLUSIONS: Staphylococcus aureus has good survival capability on cot mattress PU foam, even at low RH. Soluble material within PU can serve as carbon and nitrogen sources for bacterial growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Prolonged survival of Staph. aureus on PU at low RH could explain, in the context of the common bacterial toxins hypothesis, an increased risk of SIDS associated with used infant mattresses.     

Used cot mattresses as potential reservoirs of bacterial infection: nutrient availability within polyurethane foam

Aim: To evaluate possible source of nutrients for bacterial growth within polyurethane (PU) foam of used cot mattresses as determinants of bacterial population density. Methods and Results: Used infant mattresses (n = 30) were analysed for bacteria capable of degrading colloidal PU and for aqueous soluble chemical components (aromatic amines, ammonium ions, phosphates and protein). Mattress type (waterproof cover vs exposed PU foam at the infant‐head region), mattress age and previous use by another child were evaluated as factors that could influence the measured parameters. The levels of protein extracted from PU foam were (i) significantly (P = 0·0019) higher for mattresses lacking a waterproof cover at the infant‐head region and (ii) positively correlated with both culturable bacterial population densities of the PU foams and extent of growth of Staphylococcus aureus on aqueous leachates. No statistically significant (P > 0·05) associations between other measured parameters and mattress type/use factors were identified. Conclusions: Infant use of cot mattresses with exposed PU foam leads to accumulation of proteins within the PU, which can promote bacterial growth. Significance and Impact of the Study: The study provides a mechanistic explanation for increased levels of bacteria associated with exposed PU of cot mattresses. In the context of the common bacterial toxins hypothesis for the sudden infant death syndrome (SIDS), this could explain the lowered risk of SIDS associated with use of a waterproof cover above the mattress.     

Comparison of contact pressures measured at the sacrum of young and elderly subjects

Contact (interface) pressure measurements were made between the sacrum of groups of young and elderly subjects lying upon two special mattresses used to prevent pressure sores. One mattress was an alternating air pressure mattress, the other a foam mattress. Contact pressures were measured using a hydraulic sensor taped directly to the skin over the sacrum. All mean pressures and ‘pressure impulses’ (total applied pressure per standard time period) appeared higher when measured among the elderly subjects. Compared with the pressures measured from young subjects, the maximum contact pressures were significantly higher (p < 0.05) on both mattresses, with the pressure impulse higher while lying upon the foam mattress (p < 0.05).     

The protective effect of breast feeding in relation to sudden infant death syndrome (SIDS): III. Detection of IgA antibodies in human milk that bind to bacterial toxins implicated in SIDS

Two toxin-producing bacteria implicated in sudden infant death syndrome (SIDS) are Staphylococcus aureus and Clostridium perfringens. Epidemiological studies have shown that breast feeding reduces an infant's risk of SIDS. This protective effect could be due partly to IgA antibodies to these toxins in human milk. The aim of this work was to use a quantitative ELISA to determine levels of IgA antibodies that bound to toxic shock syndrome toxin (TSST-1), staphylococcal enterotoxin C (SEC) and C. perfringens enterotoxin A (CEA) in individual samples of human milk. All samples of milk tested contained IgA antibodies that bound to the bacterial toxins. For individual samples, IgA bound to TSST-1, SEC and CEA were in the range of 900-3100 ng ml(-1), 1000-3600 ng ml(-1) and 1000-4300 ng ml(-1) respectively. Isolation of S. aureus from mothers donating breast milk samples was used to determine if the presence of bacteria affected IgA levels which bound TSST-1 and SEC. For 3/5 samples with levels above the upper limit of the standard deviation (2375 ng ml(-1)) for IgA bound to TSST-1, S. aureus was isolated from the mother whilst 4/5 samples found to contain levels above the upper limit of the standard deviation (2627 ng ml(-1)) for IgA bound to SEC, had S. aureus isolated from the mother. In conclusion, if bacterial toxins do play a role in precipitating a SIDS death, the presence of IgA antibodies to toxins in breast milk, but not in infant formula, might contribute to the protective effect of breast feeding in relation to SIDS.     

Encasing mattresses in black plastic will not provide thermal control of bed bugs, Cimex spp. (Hemiptera: Cimicidae)

The suggestion that bed bug (Cimex spp.; Hemiptera: Cimicidae)-infested mattresses wrapped in black plastic and exposed to sunlight will be heated sufficiently to kill the bed bugs was tested. Two types of mattresses were tested: a thin mattress of solid foam rubber and a thick multilayered inner spring mattress. Temperature probes were placed on both upper and lower sides of the mattresses, which were wrapped in black plastic and placed outside on a summer day for >9 h wherein the ambient temperature peaked at 36.5 degrees C. The maximum recorded temperature on the upper (sun-exposed) sides was 85 degrees C for both mattresses, whereas lower side temperatures for the thick mattress never exceeded 35 degreesC, and some areas of the thin mattress failed to exceed 36.50C. Therefore, with published thermal death points of 40-45 degrees C depending on exposure time, and opportunities for bed bugs to avoid lethal temperatures by retreating from hot zones, this technique seems to be not suitable for bed bug management.     

The protective effect of breast feeding in relation to sudden infant death syndrome (SIDS): I. The effect of human milk and infant formula preparations on binding of toxigenic Staphylococcus aureus to epithelial cells

Epidemiological studies indicate that breast-fed infants are at a decreased risk of sudden infant death syndrome (SIDS) compared to formula-fed infants. Increasing evidence suggests that infectious agents might be involved in some of these deaths, in particular bacteria which colonise mucosal surfaces and produce superantigenic toxins. One species implicated in recent studies of SIDS infants is Staphylococcus aureus. We tested the hypothesis that in comparison to infant formula, human milk might be a better inhibitor of binding of S. aureus to epithelial cells. In this study, two protocols were used for the binding assays which were assessed by flow cytometry: the in vitro method in which bacteria were treated with milk or formula, washed and added to epithelial cells; and a method more closely reflecting the competitive interactions in vivo in which cells, bacteria, and milk or infant formula were added at the same time. With the in vivo method, breast milk caused enhancement of bacterial binding to cells whilst infant formula caused inhibition; however, for the in vitro method, both human milk and infant formula caused consistent enhancement of binding. Flow cytometry and light microscopy studies indicated that the enhancement was due to the formation of bacterial aggregates. Human milk and infant formula preparations were also compared for components (antibodies or oligosaccharides) that could inhibit binding of S. aureus using the in vitro method. Human milk contained both IgA and IgG. Neither human milk nor infant formula contained oligosaccharides reactive with the Ulex europaeus lectin but both contained components that bound monoclonal antibodies to Lewis(a) and Lewis(b) antigens which can act as receptors for S. aureus. With both methods, synthetic Lewis(a) and Lewis(b) inhibited S. aureus binding in a dose-dependent manner. With human milk, however, the only component which showed a significant correlation with inhibition of binding was the IgA specific for the staphylococcal surface component that binds Lewis(a). Both human milk and infant formula contain components which could potentially inhibit bacterial binding but only breast milk contains the IgA specific for the bacterial adhesin that binds Lewis(a). Studies using the in vivo method suggest that protection associated with breast feeding in relation to SIDS could be due mainly to the formation of bacterial aggregates. The studies have implications for further research into constituents of infant formula.     

Infectious agents, the inflammatory responses of infants and sudden infant death syndrome (SIDS)

There is no convincing epidemiological or pathological evidence that particular infectious agents cause sudden infant death syndrome (SIDS); therefore, we have explored the concept that synergy between bacterial endotoxins, exotoxins or viruses might elicit inflammatory responses during a period when the infant's endocrine system is less able to 'damp down' the effects of powerful mediators such as tumour necrosis factor or to maintain glucose homoeostasis which is affected by these mediators. This hypothesis is discussed with reference to the recent decline in the number of cot deaths.     

Synanthropic Mites of Kolkata, India: An Ecological Appraisal

Ecological observations were made on house dust mites of Kolkata as they form a major part of synanthropic mite community. Dust samples were collected with regard to the abundance of mite in relation to certain socio-ecological parameters like, habitat preference, location of house, construction pattern of house, types of mattresses used and the frequency of cleaning of mattresses. Among two different habitats examined, bed dust contained significantly higher mite population (p < 0.01) than the corresponding bedroom floor dust. The density of total mites and glycyphagids are significantly higher in rural houses in comparison to those of urban houses. In contrast, rural houses contained least number of pyroglyphids/g of dust. The density of total mites as well as pyroglyphid mites/g of dust are higher in mud house in comparison to concrete house. The density of total mites, pyroglyphids and glycyphagids are higher in cotton mattress in comparison to that of foam mattress. The frequency of cleaning has a significant effect on reducing mite densities i.e., the more the frequency of cleaning the lesser are the mite densities.     

Case-control study of sudden infant death syndrome in Scotland, 1992-5.

OBJECTIVE: To investigate the relation between routine infant care practices and the sudden infant death syndrome in Scotland. METHODS: National study of 201 infants dying of the sudden infant death syndrome (cases) and 276 controls by means of home interviews comparing methods of infant care and socioeconomic factors. RESULTS: Sleeping prone (odds ratio 6.96 (95% confidence interval 1.51 to 31.97) and drug treatment in the previous week (odds ratio 2.33 (1.10 to 4.94)) were more common in the cases than controls on multivariate analysis. Smoking was confirmed as a significant risk factor (odds ratio for mother and father both smoking 5.19 (2.26 to 11.91)). The risk increased with the number of parents smoking (P < 0.0001), with the number of cigarettes smoked by mother or father (P = 0.0001), and with bed sharing (P < 0.005). A new finding was an increased risk of dying of the syndrome for infants who slept at night on a mattress previously used by another infant or adult (odds ratio 2.51 (1.39 to 4.52)). However, this increased risk was not established for mattresses totally covered by polyvinyl chloride. CONCLUSIONS: Sleeping prone and parental smoking are confirmed as modifiable risk factors for the sudden infant death syndrome. Sleeping on an old mattress may be important but needs confirmation before recommendations can be made.     

Effects of jet-fuel microbial isolates on a polyurethane foam

Jet-fuel microbial isolates were studied for effects on a polyurethane foam material that has been proposed as a baffling material for use in aircraft fuel tanks. Evidence was found that a polyesterurethane foam gave increased cell counts and oxygen uptake with a bacterial isolate, and extensive matting with fragmentation and decreases in tensile strength of the foam with a fungal isolate. The polyurethane foam was affected by activity of the jet-fuel microbial isolates to an extent that would cause serious microbiological problems in the fuel tanks of jet aircraft.     

Detection of pyrogenic toxins of Staphylococcus aureus in sudden infant death syndrome

It has been suggested that pyrogenic toxins of Staphylococcus aureus are involved in the series of events leading to some cases of sudden infant death syndrome (SIDS). The objectives of the study were to screen tissues from SIDS infants for pyrogenic toxins and to compare incidence of identification of these toxins among these infants from different countries. An enzyme-linked immunosorbent assay (ELISA) and a flow cytometry method were used to screen body fluids and frozen or formalin-fixed tissues for pyrogenic toxins of S. aureus, toxic shock syndrome toxin 1 (TSST), staphylococcal enterotoxins A (SEA), B (SEB), and C1 (SEC). Toxins were identified in tissues of 33/62 (53%) SIDS infants from three different countries: Scotland (10/ 19, 56%); France (7/13, 55%); Australia (16/30, 53%). In the Australian series, toxins were identified in only 3/19 (16%) non-SIDS deaths (chi2 = 5.42, P < 0.02). The flow cytometry method was useful for toxin detection in both frozen and fixed tissues, but ELISA was suitable only for frozen tissues or those fixed for less than 12 months. Identification of pyrogenic toxins in > 50% of SIDS infants from three different countries indicated further investigation into the role the toxins play in cot deaths might result in development of additional measures to reduce further the incidence of these infant deaths.     

Mould biodiversity in homes II. Analysis of mattress dust

Fungal species from 130 samples of mattress dust have been identified. The number of moulds varies from one mattress to another with extreme values ranging from less than 1000 to more than 70 000 000 CFU/g of dust (median value of 30 000 CFU/g).Eurotium repens is undoubtedly the most frequent species detected in mattress dust.Aureobasidium pullulans, Alternaria alternata, Penicillium chrysogenum, Aspergillus penicilloides andAspergillus restrictus, which were frequently isolated and/or revealed important concentrations in dust samples, are the other main occurring species. Fungal flora in mattresses are more numerous in winter, the peak period being December-January. The most important contaminations by xerophilic species occurred during that peak period, whereas non-osmophilous species were constantly present during the year. The qualitative conditions of the habitat have an influence on the abundance of moulds in mattresses. Mattresses from damp houses could be a source forAlternaria throughout the year. No significant difference has been detected between the contamination level of men and women's mattresses (P=0.651). Children's mattresses are less contaminated than adults (P=0.025). The level of contamination could be affected by perspiration.     

Use of bioluminescence for detection of genetically engineered microorganisms released into the environment.

The persistence and movement of strain JS414 of Xanthomonas campestris pv. campestris, which was genetically engineered to bioluminesce, were monitored during a limited field introduction. Bioluminescence and traditional dilution plate counts were determined. Strain JS414 was applied to cabbage plants and surrounding soil by mist inoculation, by wound inoculation, by scattering infested debris among plants, and by incorporating bacteria into the soil. Bioluminescent X. campestris pv. campestris was detected in plant samples and in the rhizosphere up to 6 weeks after inoculation. Movement to uninoculated plants was detected on one occasion, but movement from the immediate release area was not detected. Strain JS414 was detected in soil samples beneath mist- and wound-inoculated plants only at intentionally infested locations and in aerial samples only on the day of inoculation. Our bioluminescence methods proved to be as sensitive as plating methods for detecting the genetically engineered microorganisms in environmental samples. Our results demonstrate that transgenic incorporation of the luxCDABE operon provides a non-labor-intensive, sensitive detection method for monitoring genetically engineered microorganisms in nature.     

Natural-Y Même polyurethane versus smooth silicone: analysis of the soft-tissue interaction from 3 days to 1 year in the rat animal model

The polyurethane foam-covered breast prosthesis is experiencing increased clinical use. The polyurethane is felt to be responsible for altering capsule formation and reducing the contracture rate. This study characterizes the soft-tissue response to the Natural-Y Même polyurethane foam versus smooth silicone in a rat model. Implants were fashioned from an unbacked polyurethane foam specimen used to cover the Natural-Y prosthesis, a silicone shell covered with the Natural-Y foam, and a smooth silicone control. Materials were placed subcutaneously into the backs of male Lew/SsN rats (n = 81) for 3, 7, 14, and 28 days and 3, 6, and 12 months. Implants were then harvested with their soft-tissue response and evaluated histologically. Analysis demonstrates that microstructuring of a surface, as opposed to a smooth material, will dramatically alter the early, intermediate, and late wound-healing events. The soft-tissue response was observed to be dependent on implant site, material chemistry, and morphology as characterized by exudate formation, macrophage invasion, multinucleated giant cell formation, collagen deposition, foam degradation, and angiogenesis.     

Use of Bioluminescence for Detection of Genetically Engineered Microorganisms Released into the Environment

The persistence and movement of strain JS414 of Xanthomonas campestris pv. campestris, which was genetically engineered to bioluminesce, were monitored during a limited field introduction. Bioluminescence and traditional dilution plate counts were determined. Strain JS414 was applied to cabbage plants and surrounding soil by mist inoculation, by wound inoculation, by scattering infested debris among plants, and by incorporating bacteria into the soil. Bioluminescent X. campestris pv. campestris was detected in plant samples and in the rhizosphere up to 6 weeks after inoculation. Movement to uninoculated plants was detected on one occasion, but movement from the immediate release area was not detected. Strain JS414 was detected in soil samples beneath mist- and wound-inoculated plants only at intentionally infested locations and in aerial samples only on the day of inoculation. Our bioluminescence methods proved to be as sensitive as plating methods for detecting the genetically engineered microorganisms in environmental samples. Our results demonstrate that transgenic incorporation of the luxCDABE operon provides a non-labor-intensive, sensitive detection method for monitoring genetically engineered microorganisms in nature.     

Toxigenic bacteria and sudden infant death syndrome (SIDS): nasopharyngeal flora during the first year of life

Many developmental and environmental risk factors for sudden infant death syndrome (SIDS) are similar to those for susceptibility to respiratory tract infection, and toxigenic bacteria have been implicated in some SIDS cases. We assessed nasopharyngeal flora of healthy infants in relation to risk factors to determine which species best lit the mathematical model proposed for the common bacterial toxin hypothesis and if these findings complemented results obtained from SIDS cases which occurred during the period of the survey. Longitudinal studies were carried out between April 1993 and March 1996 on 253 healthy infants and their mothers. 150 from a multiply deprived area, 103 from an affluent area. Concurrent SIDS infants (37) were screened for nasopharyngeal flora. Among healthy infants < or = 3 months of age, the predominant isolate was Staphylococcus aureus 57% compared with 86% for SIDS infants in that age range (P< 0.02). There were significant associations between isolation of different species from both mother and baby but no association between isolation of any species with: area of residence: parental smoking habits; breast or bottle feeding; symptoms of viral infection: seasonality. We conclude that S. aureus fits the mathematical model for SIDS. Both staphylococci and/or their toxins were identified in a significant proportion of SIDS cases. Isolation of staphylococci from healthy infants was associated with the 2-4-month age range, a risk factor consistently found in all epidemiological studies of SIDS. This might reflect the developmental stage in which 80-90% of infants express the Lewis(a) antigen which we have shown to be one of the receptors for S. aureus.     

Endpiece: Genius (1815)

ObjectiveTo examine the proposition that a used infant mattress is associated with an increased risk of sudden infant death syndrome.DesignCase-control study.SettingScotland (population 5.1 million, with about 53 000 births a year).Participants131 infants who died of sudden infant death syndrome between 1 January 1996 and 31 May 2000 and 278 age, season, and obstetric unit matched control infants.ResultsRoutine use of an infant mattress previously used by another child was significantly associated with an increased risk of sudden infant death syndrome (multivariate odds ratio 3.07, 95% confidence interval 1.51 to 6.22). Use of a used infant mattress for last sleep was also associated with increased risk (6.10, 2.31 to 16.12). The association was significantly stronger if the mattress was from another home (4.78, 2.08 to 11.0) than if it was from the same home (1.64, 0.64 to 4.2).ConclusionA valid significant association exists between use of a used infant mattress and an increased risk of sudden infant death syndrome, particularly if the mattress is from another home. Insufficient evidence is available to judge whether this relation is cause and effect.

What is already known about this topic

The major risk factors for sudden infant death syndrome are sleeping prone and parental smokingOne study has suggested that the syndrome is associated with sleeping on an infant mattress previously used by another child

What this study adds

New case-control data show that the association between a previously used infant mattress and sudden infant death syndrome is validWhen source of used mattress is categorised, the association is significant only if the mattress is from another homeInsufficient evidence is available to judge whether this is a cause and effect relation     

Usage of high‐performance mattresses for transport of Indo‐Pacific bottlenose dolphin

Ground transport can be a stressful operation for dolphins if the long period of restraint causes damage to internal organs, especially to the lung, generated by their own weight. Buoyancy is deprived from dolphins under moist transport, in which dolphins are transported on mattresses. Upgrading mattresses is an effective way to modify the transportation method so as to compensate for the loss of buoyancy. In Indo‐Pacific bottlenose dolphins (Tursiops aduncus), we tried to find mattresses that performed well at distributing the dolphins' weight and preserved their pulmonary function. When using EV‐17 (thickness, 50 mm) put on EE‐20 (thickness, 50 mm), a wider support area, less extreme changes in pressure, and lower maximum pressures were observed compared with other mattress systems tested. On this mattress system, lower breathing rates, lower heart rates, and higher exhaled CO₂ concentrations were shown compared with using standard mattresses. These results suggest that the performance of the combination of EV‐17 and EE‐20 is better than that of the standard mattress in terms of the cardiopulmonary function of dolphins. Zoo Biol 27:331–340, 2008. © 2008 Wiley‐Liss, Inc.     

Quantification of Staphylococcus aureus and Escherichia coli in the liquid medium by fluorimetry and its use in phagocytosis assay

A fluorimetric technique was compared with the plate counting method for quantification of viable cells of Staphylococcus aureus and Escherichia coli in the liquid medium. The fluorimetric assay measures the release of fluorogenic 4-methylumbelliferone (4-MU) from 4-methylumbelliferyl phosphate by the bacterial phosphatases. The increase in fluorescence was dependent on the size of bacterial inocula. Setting the fluorescence threshold at the middle of the logarithmic growth phase resulted in good linear relationship between bacterial counts and fluorescence ( r = 0·99 for both Staph. aureus and E. coli ). There was also an excellent correlation between the fluorimetric assay and the plate counting method in quantifying viable bacteria in saline ( r = 0·99). Both methods were further compared for evaluation of extracellular bacteria following phagocytosis. The fluorimetric technique, in general, gave a higher percentage of phagocytosis than the plate counting method with statistical significance for E. coli.