Low dose, early mucosal exposure will minimize the risk of microbial disease.

In the 21st century we will rediscover the germ theory of disease: germs not only cause infection as described in standard textbooks but also have a pathogenic role in autoimmunity, atherosclerosis, cancer and even acute psychiatric conditions. In order to reduce morbidity and mortality caused by common organisms we should ensure that exposure is early, often, by the mucosal route and in low dose. Micro-organisms should be delivered daily throughout life by respiratory mucosal spray or enteric coated pill, in precise dose and in a predetermined schedule.

Postmortem cerebrospinal fluid pleocytosis: a marker of inflammation or postmortem artifact?

The aim of this paper is to reassess the significance of postmortem cerebrospinal fluid pleocytosis. Published articles of CSF changes after death were reviewed, and reanalysis, in the light of modern views on the significance of bacterial postmortem isolates, was undertaken. There is theoretical and experimental evidence that the blood brain barrier to the movement of protein and cells is preserved in the first few hours after death. The number of mononuclear cells in the cerebrospinal fluid does rise in the first 24 hours after death, and this is most probably due to detachment of leptomeningeal lining cells. But the marked increase in lymphocyte counts seen in some cases of sudden infant death syndrome (SIDS) and in other deaths in the paediatric age range could well be a marker of inflammation.

The effect of Staphylococcus aureus carriage in late pregnancy on antibody levels to staphylococcal toxins in cord blood and breast milk.

We investigated the effect of carriage of Staphylococcus aureus in the later stages of pregnancy on levels of antibody specific to the S. aureus toxins, staphylococcal enterotoxin B (SEB), staphylococcal enterotoxin C (SEC) and toxic shock syndrome toxin-1 (TSST-1), in cord blood and breast milk and also explored the relationship between levels of antibody in antenatal serum and cord blood. Nasopharyngeal swabs and stool samples were collected on two occasions, from 96 women, during the last 6 weeks of pregnancy. Samples were cultured and S. aureus isolates were identified. Antenatal and cord blood samples from the same women and their infants were analysed for IgG antibody to SEB, SEC and TSST-1 by enzyme-linked immunosorbent assay. Breast milk samples were analysed for IgA antibody to the same toxins. We found that S. aureus carriage in pregnancy is common and exposure to a toxin-producing isolate boosts immunity. Over 89% of women and infants have some protective antibody to the toxins, and antitoxin IgG levels are higher in cord blood samples compared with antenatal samples. Levels of cord blood IgG and breast milk IgA specific for the staphylococcal toxins vary. Some infants lack protection and could be at risk of toxin-induced disease.

Transient bacteraemia: a possible cause of sudden life threatening events.

The concept proposed is that transient bacteraemia occurring in otherwise healthy individuals can cause acute life threatening events due to bacterial toxaemia even though the bacteraemia is rapidly cleared (<20 min). This is most likely to occur in infancy at around two to three months of age when anti-toxin IgG reaches its nadir. Sudden unexpected death in infancy, acute life threatening events, haemorrhagic shock and encephalopathy, and the triad of retinal haemorrhage, encephalopathy and bilateral thin film subdural haematomata are conditions which could be caused by this mechanism. Investigations need to be directed to measuring bacterial toxins in blood, CSF and urine; anti-toxin IgG in blood; and bacterial specific nucleic acid sequences in blood, CSF and urine using polymerase chain reaction in order to confirm recent bacteraemia. Furthermore the upper respiratory tract bacterial flora should be mapped in cases and appropriately matched live healthy community controls. Sudden onset, profound life threatening physiological dysfunction occurring in later life could also be caused by a similar mechanism and should be investigated in a similar way; candidate conditions include epilepsy, migraine, stroke and cardiac arrhythmias.

Detection of specific antibodies in cord blood, infant and maternal saliva and breast milk to staphylococcal toxins implicated in sudden infant death syndrome (SIDS).

The common bacterial toxins hypothesis of sudden infant death syndrome (SIDS) is that nasopharyngeal bacterial toxins can trigger events leading to death in infants with absent/low levels of antibody that can neutralise the toxins. The aim of this study was to investigate nasopharyngeal carriage of Staphylococcus aureus and determine levels of immunity in the first year of life to toxic shock syndrome toxin (TSST-1) and staphylococcal enterotoxin C (SEC). Both toxins have been implicated in SIDS cases. Seventy-three mothers and their infants (39 males and 34 females) were enrolled onto the study. The infants had birth dates spread evenly throughout the year. In infants, S. aureus carriage decreased significantly with age (P<0.001). Between 40% and 50% of infants were colonised with S. aureus in the first three months of life and 49% of the isolates produced one or both of the staphylococcal toxins. There was a significant correlation between nasopharyngeal carriage of S. aureus in mothers and infants in the three months following the birth (P<0.001). Carriage of S. aureus in infants and their mothers was not significantly associated with levels of antibody to TSST-1 or SEC in cord blood, adult saliva or breast milk. Infants colonised by S. aureus had higher levels of salivary IgA to TSST-1 than infants who were culture negative. Analysis of cord blood samples by a quantitative ELISA detected IgG bound to TSST-1 and SEC in 95.5% and 91.8% of cases respectively. There was a marked variation in levels of maternal IgG to both TSST-1 and SEC among cord blood samples. Maternal age, birth weight, and seasonality significantly affected the levels of IgG binding to TSST-1 or SEC. Analysis of infant saliva samples detected IgA to TSST-1 and SEC in the first month after birth; 11% of samples tested positive for salivary IgA to TSST-1 and 5% for salivary IgA to SEC. By the age of two months these proportions had increased to 36% and 33% respectively. More infants who used a dummy tested positive for salivary IgA to TSST-1 compared to infants who did not use a dummy. Levels of IgA to TSST-1 and SEC detected in the breast-milk samples varied greatly among mothers. There was a trend for infants receiving breast milk with low levels of antibody to TSST-1 or SEC to have higher levels of salivary antibody to the toxins. In conclusion, passive immunity to toxins implicated in SIDS cases varies greatly among infants. Infants are able to mount an active mucosal immune response to TSST-1 and SEC in the first month of life.