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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. [ABSTRACT FROM AUTHOR]

r.o. jenkins and r.e. sherburn. 2005. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]