The aim of the investigation was to determine the effect of age, gender, viral upper respiratory tract infection (URTI), season and sleeping position on the composition of the nasopharyngeal bacterial flora in infancy. Seventy-two babies, 38 male and 34 female, whose birthdates were evenly spread throughout the year were followed from birth to 18 months of age. From 0 to 6 months nasopharyngeal swabs were obtained once a month in periods without URTI and daily for 3 days during episodes of URTI. From 12 to 18 months of age nasopharyngeal swabs were obtained in the early morning alter an overnight sleep and later in the day after the baby had been up for over 2 h. Swabs were obtained in prone and supine sleepers with and without infection. In infants aged 0-6 months URTI had little effect on the nasopharyngeal bacterial flora, but there was a marked effect of age and less marked effect of season and gender. In particular Staphylococcus aureus carriage decreased with age, was most common in the winter months and the density of colonisation was greater in males than females. In infants aged 12-18 months the combination of prone sleeping with URTI and an early morning swab led to increased carriage of staphylococci, streptococci. Haemophilus influenzae and Gram-negative bacilli which are not normally part of the nasopharyngeal flora. These results are relevant to sudden infant death syndrome (SIDS). The combination of prone sleeping and URTI reproduces the nasopharyngeal flora seen in SIDS. Gram-negative bacilli isolated from SIDS cases should not be dismissed as post-mortem contaminants. The features of S. aureus make it a prime candidate for a pathogenic role in SIDS.
The incidence of campylobacter enteritis in Lancaster City Health Authority is three times the UK average for similar sizes of population and has marked seasonal peaks in May and June. Environmental monitoring of surface waters around Lancaster showed that thermophilic campylobacters were absent from drinking water from the fells and from the clean upper reaches of the River Conder but were present in the main rivers entering Morecambe Bay, the lower reaches of the River Conder, the Lancaster canal, and seawater from the Lune estuary and Morecambe Bay. All the surface waters tested showed the same seasonality, namely, higher numbers in the winter months and low numbers or none in May, June and July. The absence of thermophilic campylobacters in the summer months may be due to high sunshine levels because experiments on the effects of light showed that campylobacters in sewage effluent and seawater were eliminated within 60 and 30 min of daylight respectively but survived for 24 h in darkness. As the concentrations of campylobacters in surface waters were at their lowest precisely at the time of peak infections in the community it is unlikely that surface waters form Lancaster's reservoir of campylobacter infection for the community.
Aims: To investigate the hypothesis that commonly occurring bacterial toxins cause sudden infant death syndrome (SIDS) by (1), determining in which tissues bacterial toxins are concentrated after intravenous injection in rats; and (2), seeing if the same tissues contain detectable toxins in cases of SIDS. Methods: The tissue distribution of intravenously injected staphylococcal enterotoxin A (SEA), enterotoxin B (SEB), enterotoxin C (SEC), enterotoxin D (SED), toxic shock syndrome toxin (TSST-1), and a-haemolysin was studied in rats using immunohistology and polyacrylamide gel electrophoresis with immunoblotting. Immunostaining was also carried out on formalin fixed kidneys from cases of SIDS and a comparison series of necropsy cases using anti-SEA, anti-SEB, anti-SEC2 and anti-SED. Results: Immunohistology showed that SEB, SEC, SED and TSST-1 were all concentrated in the proximal convoluted tubular cells ofthe kidney. The Bead cultures stored at -70'C were grown on blood agar overnight at 37'C, then transferred to bijou bottles containing 5 ml brainheart infusion (BHI) medium, and again left overnight at 37'C. Two drops of the culture were spread on dialysis membrane overlying BHI-1 5% agar plates and incubated for three to four days at 37'C in 5% CO2. Phosphate buffered saline (PBS) (2 ml) was used to wash the growth from the membrane and the suspension was centrifuged at 4000 x g for 15 minutes. The supernatant was sterilised by passing through a 0 2 ,um Minisart disposable filter and stored at -20°C. ELECTROPHORESIS AND IMMUNOBLOTIINGToxin preparations were examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), using a 1-5 mm slab gel containing 12% (WY) acrylamide for the separating gel and a 4% acrylamide for the stacking gel. The buffer system was a slightly modified version of Laemmli. 12 The sample buffer contained 2% SDS, 10% sucrose, 002 M TRIS-HCI (pH 8 0), 0-002 M EDTA and 2 mg Pyronin Y as marker dye. (Mercapto-ethanol was added to the sample buffer for most toxins but was found to break down SEB into small fractions.) Equal quantities of sample and sample buffer were used at 25 ,um/well.Electrophoresis was carried out in "The Sturdier" vertical slab unit, SE 400 (Hoefer Scientific Instruments).Immediately after electrophoresis the separating gels were soaked in transfer buffer (0-25 MTRIS, 0-192 M glycine in 20% methanol) for 15 minutes before blotting. The separated proteins were transferred to nitrocellulose membrane for one hour at 100 mA, 716 on 10 May 2018 by guest. Protected by copyright.
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