BACTERIAL SEPSIS AND MENINGITIS - Nizet Laboratory at UCSD

A streptococcal infection now is reported infrequently
[37–43], but it can occur rarely in epidemic form in nurseries
[37,44–47]. The reemergence of virulent group A
streptococcal infections during the last 3 decades, including
invasive disease and toxic shock syndrome, has been
reflected in more case reports of severe disease in
pregnant women and newborns.
Group A streptococcal disease in the mother can affect
the fetus or newborn in two clinical patterns. Maternal
streptococcal bacteremia during pregnancy can lead to
in utero infection resulting in fetal loss or stillbirth; alternatively,
acquisition of group A streptococci from the
maternal genital tract can cause early-onset neonatal sepsis
similar to early-onset group B streptococcal disease. In
the first form of disease, previously healthy pregnant
women with influenza-like signs and symptoms have
been reported. This presentation rapidly progressed to
disseminated intravascular coagulopathy and shock, with
high mortality and risk to the fetus or newborn [48–50].
The features of 38 cases of neonatal invasive group A
streptococcal infection from the literature were catalogued
more recently [51]. Overall mortality rate in
neonatal invasive group A streptococcal infection was significantly
high (31%). Most of these infants presented
with early-onset infection (62%), with many occurring
in the first 48 hours of life. A specific focus of group A
streptococcal infection was documented in three quarters
of cases—42% of neonates had pneumonia, sometimes
complicated by empyema, and 17% had a toxic shock
syndrome–like presentation. Among the cases of earlyonset
group A streptococcal infection, puerperal sepsis
or toxic shock syndrome–like sepsis in the mother during
the peripartum period was an associated factor in 62% of
cases. In late-onset cases of neonatal group A streptococcal
infection reviewed in this series, soft tissue infections,
meningitis, and pneumonia were among the reported
clinical manifestations. An earlier review by Greenberg
and colleagues [52] on 15 cases of group A streptococcal
neonatal infection yielded similar statistics on clinical presentations
and mortality.
In addition to sepsis, meningitis, and toxin-mediated
disease in the neonate, focal infections, including cellulitis,
omphalitis, Ludwig angina [53], pneumonia, and osteomyelitis,
have been reported. Because all group A
streptococci are susceptible to b-lactam antibiotics, the
current strategy for prevention or treatment of infections
caused by GBS also could apply to infections caused by
group A streptococci.
STREPTOCOCCUS PNEUMONIAE
Although pneumococcal infections in the neonate are
unusual occurrences, they are associated with substantial
morbidity and mortality [54–61]. Bortolussi and colleagues
[54] reported five infants with pneumococcal sepsis
who had respiratory distress and clinical signs of infection
on the first day of life. Three infants died, two within 12
hours of onset. S. pneumoniae was isolated from the vaginas
of three of the mothers. Radiographic features were
consistent with hyaline membrane disease or pneumonia
or both. The clinical features were strikingly similar to
features of early-onset group B streptococcal infection,
CHAPTER 6 Bacterial Sepsis and Meningitis
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including the association of prolonged interval after
rupture of membranes, early-onset respiratory distress,
abnormal chest radiographs, hypotension, leukopenia,
and rapid deterioration. Fatal pneumococcal bacteremia
in a mother 4 weeks postpartum and the same disease
and outcome in her healthy term infant, who died at
6 weeks of age, suggested an absence of protective antibody
in the mother and the infant [55].
Hoffman and colleagues from the United States Multicenter
Pneumococcal Surveillance Group [59] identified
20 cases of neonatal S. pneumoniae sepsis or meningitis
in a review of 4428 episodes of pneumococcal infection at
eight children’s hospitals from 1993-2001. Ninety percent
of the infants were born at term, with a mean age at the
onset of infection of 18.1 days. Only two of the mothers
had clinically apparent infections at the time of delivery.
Eight neonates had meningitis, and 12 had bacteremia;
4 of the bacteremic neonates also had pneumonia. The
most common infecting pneumococcal serotypes were 19
(32%), 9 (18%), and 18 (11%). Penicillin and ceftriaxone
nonsusceptibility were observed in 21.4% and 3.6% of isolates.
Three deaths (15%) occurred, all within 36 hours of
presentation. A case report of peripartum transmission of
penicillin-resistant S. pneumoniae underlines concern that
the increasing use of peripartum ampicillin to prevent
group B streptococcal disease in neonates may result in
an increase in neonatal infections caused by b-lactam–
resistant organisms [60].
OTHER STREPTOCOCCI
Human isolates of group C and G streptococci form large
b-hemolytic colonies that closely resemble those of group
A streptococcus and share many virulence genes, including
genes encoding surface M proteins and the cytotoxin
streptolysin S. Group C streptococci have been associated
with puerperal sepsis, but neonatal sepsis or meningitis
related to these organisms is rare [62–65]. Likewise,
group G streptococci are an infrequent cause of neonatal
sepsis and pneumonia [66–70]. Maternal intrapartum
transmission was the likely source for most cases [68],
and concurrent endometritis and bacteremia in the
mother and sepsis in the neonate have been reported
[69]. Dyson and Read [68] found very high rates of colonization
in neonates born at New York Hospital in a
1-year survey of discharge cultures in 1979; the monthly
incidence of cultures of group G streptococci from the
nose and umbilicus ranged from 41% to 70%. During
this period, group B streptococcal colonization was only
1% to 11% [68].
Viridans streptococci are a heterogeneous group of
a-hemolytic and nonhemolytic streptococci that are constituents
of the normal flora of the respiratory and gastrointestinal
tracts of infants, children, and adults. There are
several classification schemata for these streptococci, and
they may bear different designations in the literature.
Streptococcus bovis is capable of causing neonatal sepsis
and meningitis that is clinically similar to sepsis caused
by GBS [71–73]. Rare cases of neonatal sepsis caused by
Streptococcus mitis have been reported [74,75].
Viridans streptococci accounted for 23% of isolates
from cultures of blood and CSF obtained from neonates