Dozens of newborn babies in Japan have suffered toxic shock syndrome, a new
study shows. The disease is caused by the superbug MRSA, which is spreading in
the US and Europe as well as Japan. Researchers now believe newborns worldwide
face a growing risk of toxic shock.
鈥淚 think it will be a significant problem in the future,鈥� says Patrick
Schlievert, a microbiologist at the University of Minnesota who in 1981
discovered that some strains of MRSA cause toxic shock. 鈥淚t鈥檚 been thought that
toxic shock syndrome was an illness of teenagers and adults, and neonates were
always excluded.鈥�
In 1995, Naoto Takahashi and his colleagues at Tokyo Women鈥檚 Medical
University encountered several newborns who suffered from fever, extensive
rashes and a low platelet count, which made them bruise easily. All the infants
were found to be infected with a strain of the drug-resistant bacterium
MRSA鈥攎ethicillin-resistant Staphylococcus aureus鈥攖hat
produces 鈥渢oxic shock syndrome toxin鈥� (TSST).
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TSST is known as a superantigen. Rather than generating the normal mild and
highly specific immune response, it activates an entire class of immune cells
indiscriminately. These cells, called Vbeta2+ T cells, usually account for 18
per cent of the body鈥檚 T cells. But when activated by a superantigen, they
divide until the proportion rises to 70 per cent. Once most of the body鈥檚 T
cells are active, toxic shock ensues and the patient鈥檚 kidney, liver, heart and
lungs are impaired.
Takahashi鈥檚 sick babies had high levels of Vbeta2+ T cells as well as some
symptoms of toxic shock. He surveyed the major neonatal care units in Japan to
find out how many had seen babies with the illness, to which he gave the acronym
NTED. A quarter of the hospitals he contacted had seen NTED babies during 1995.
By 1998 more than two-thirds were reporting cases of NTED. 鈥淚n my hospital we
have seen more than 70 cases of NTED,鈥� says Takahashi.
But NTED is likely to be even more widespread, Schlievert says. Most doctors
are unlikely to recognise the condition because not all the classic symptoms of
toxic shock necessarily appear in newborn babies. Infants are very resistant to
fever and are less likely to develop low blood pressure than adults. So they
might appear to have a routine infection. Furthermore, doctors usually associate
MRSA with extended hospital stays or surgery, not the maternity ward. Since
superantigen-producing MRSA thrives in mucosal membranes, exposed mothers may
already have vaginal infections when they give birth, passing it on to their
baby.
MRSA is on the rise outside hospitals, too. Last year, four children in
Minnesota died from MRSA infections acquired outside a medical facility. 鈥淭he
problem is that physicians aren鈥檛 thinking they have to deal with MRSA out in
the community. So they treat with penicillin and the neonate doesn鈥檛 respond,鈥�
Schlievert says. 鈥淏y the time you do find the right antibiotic, the patient is
going to die.鈥�
Newborn toxic shock may be preventable if caught early. Takahashi says that
infants who carry MRSA but show no symptoms may have received anti-TSST
antibodies from their mothers. Schlievert adds that a dose of intravenous
antibodies against TSST should prove an effective treatment in babies.