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.

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Matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS) was investigated as a method for the rapid identification of yeast cells. Following pretreatment of yeast samples with a cell wall digesting enzyme (lyticase), distinct and reproducible mass spectra over them/zrange 2,000 to 16,000 were obtained by MALDI-TOF-MS. Using an optimised procedure, characteristic mass spectra that distinguished between Candida spp. and between strains of Saccharomyces cerevisiae were produced. The approach offers the potential for rapid differentiation of yeasts in clinical diagnosis and in the fermentation industries.

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 0AE85% 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.

Aim: To investigate aerial release of bacteria from used cot mattresses and to assess factors that may influence this process. Methods and Results: Movement on used mattresses, simulating that of an infant's head, significantly enhanced aerial release of naturally acquired bacteria from the polyurethane foams (total count data, P ¼ 0AE008; Staphylococcus aureus, P ¼ 0AE004) or from polyvinyl chloride covers (total count data, P ¼ 0AE001). Aerial release of naturally acquired bacteria from used cot mattresses showed high variability and was poorly correlated (R 2 £ 0AE294) with bacterial cell density within the materials. In experiments involving inoculation of S. aureus and Escherichia coli onto the polyurethane of unused cot mattresses, aerial release of the species correlated well (R 2 ‡ 0AE950) with inoculation density when simulated infant head movement was applied. Aerial release of these bacterial species from the material decreased with increase in width or aqueous content of the material, and was lower from polyurethane foam of a used cot mattress. Conclusions: Simulated infant movement and mattress related factors influence aerial release of bacteria from cot mattress materials. With simulated infant movement on cot mattress polyurethane foam, levels of airborne bacteria above the material are proportional to bacterial population levels inoculated onto the material. Significance and Impact of the Study: Cot mattresses harbouring relatively high levels of naturally acquired toxigenic bacteria, such as S. aureus, could pose a relatively high risk of infection to the infant's respiratory tract through increased aerial contamination. This has impact in the context of recent findings on cot mattress related risk factors for sudden infant death syndrome.