3. Discussion
In this case report, a premature infant was infected in utero with L.
monocytogenes from her mother. The mother experienced headaches at 6
months gestation, then developed symptoms of fever and abdominal pain at
33 weeks. These symptoms were consistent with maternal antenatal
symptoms presented in a report of 12 cases of perinatal listeriosis:
mothers had clear neutropenia during their illness, which was also
present in the case reported here [5]. Therefore, cases of
antepartum fever with abdominal pain should be treated cautiously.
The infant in this case had early onset listeriosis; she was born
prematurely at 33 weeks and died 72 hours after birth. The clinical
features were typical of early-onset neonatal listeriosis, including
preterm delivery and sepsis at birth [6]. The causes of death
included sepsis, secondary meningitis, necrotizing enterocolitis, and
septic shock.
We administered emergency treatment for perinatal infection, but the L.
monocytogenes was not detected early enough. We made the judgment that
neonatal infection was likely on the basis of the clinical symptoms of
neonatal respiratory distress, lethargy, and poor responsiveness.
Because most of the pathogenic bacteria responsible for early neonatal
sepsis are Gram-positive cocci [7], we administered flomoxef because
of its wide antibacterial spectrum and safety [8]. After L.
monocytogenes was suspected, antimicrobial therapy was switched to
amoxicillin and sulbactam combined with imipenem/cilastatin. Although
the infant died 10 hours later, the mother improved significantly within
1 to 2 days of treatment with piperacillin and sulbactam following the
identification of L. monocytogenes in the infant’s blood culture.
Generally, early diagnosis of mother-to-child Listeria infection
is challenging. In this case, the mother’s blood cultures were twice as
negative. In a retrospective case study, only 36% of 11 pregnant women
with perinatal listeriosis had positive blood cultures [9]; thus,
false negatives are very common. We speculate that the high false
negative rate may be related to the collection conditions of blood
cultures. In principle, blood samples should be collected at the
patient’s body temperature above 38.5 °C without using antibiotics and
submitted for testing within 30 min. However, this condition is not easy
to achieve in most situations.
Several factors may explain the different results of treatment of the
infant and mother with antibiotics effective against Listeria .
Most importantly, neonatal immune function is poor, the disease
progresses faster, the complications are critical, and the mortality
rate is high. Moreover, in clinical diagnosis, a negative blood culture
should not be interpreted as non-septicemia. When neonatal infection
progresses rapidly and accurate results of blood cultures are
unavailable, empirical diagnosis is more important. Ampicillin can
simultaneously cover L. monocytogenes, beta-hemolytic streptococci, andE. coli , the latter two bacteria are the most common and harmful
pathogens associated with neonatal early-onset sepsis [10].
In the treatment of this case, a multi-pronged approach was applied in
addition to antimicrobial therapy that included the use of an incubator,
sterilization, ventilator-assisted breathing, heart-brain protection,
and so on. These interventions are vital to ensure the operation of the
organs and maintain circulation. Before the onset of complications
(e.g., 24 hours after birth, Table 1), the infant’s condition improved
slightly.
There were some limitations to this retrospective case report that
require clarification. First, Listeria shows placental tropism
and placental specimen culture is the most sensitive method for
diagnosing neonatal listeriosis [11]. However, the placenta was not
cultured in this case and the results of the mother’s blood culture were
twice negative. In this case, the infant was born with symptoms of
sepsis, and the mother’s improvement following the administration of
antibiotics effective against Listeria along with negative blood
cultures was sufficient to demonstrate that the infection was
congenital. The failure to identify listeriosis earlier is a major
factor preventing the rescue of newborns. Second, without detailed
epidemiological information, including the mother’s medical history, it
was not possible to determine the source of Listeria infection.
The diagnosis of neonatal Listeria infection has three
characteristics. No specific clinical symptoms. The diagnosis of
biological samples has different degrees of false negatives [12]. In
addition, newborns have experienced circulatory failure, shock, and
death before Listeria can be isolated and identified.
Considering our experience with this case, we conclude that although
bacterial culture is vital for the diagnosis of listeriosis [13],
clinicians should not wait for final confirmation of the pathogen when
the infant is in critical condition. Instead, clinicians should assess
the medical history of the mother and the infant at the same time and
monitor changes in their conditions. Bacterial culture and
identification results should be evaluated in combination with clinical
experience. Clinicians should remain alert to the possibility of
specific bacterial infections and be ready to change antimicrobial
therapy in a timely fashion.
4. Conclusions
This pathological report demonstrates that monocytosis caused byListeria monocytogenes poses a significant threat to the lives of
newborns. The bacterium can cross the placental barrier, leading to
neonatal listeriosis when transmitted from infected mothers. This
disease progresses rapidly, has a poor prognosis, and carries an
extremely high mortality rate. Furthermore, the empirical use of
cephalosporins and carbapenems has shown resistance. These findings
highlight the importance of early identification of the pathogen in the
treatment of neonatal listeriosis. However, blood culture identification
is associated with long turnaround times and a high false-negative rate,
necessitating the establishment of an early and sensitive comprehensive
testing system for this bacterium. It is particularly crucial to
strengthen screening for high-risk pregnant women during the perinatal
period. More importantly, healthcare professionals should increase their
awareness and attention to rare pathogens that can traverse the
placental barrier.
Author Contributions:Xiaoyu Chen - project
administration; Jing Li - visualization;Ying Lu, Shuyue
Li and Qi Li - original draft preparation; Yakun Luo - review
and editing; Fan Wang - original draft preparation;Qingliang Shao - original draft preparation, funding
acquisition and supervision.
Funding: This research was funded by Bethune Medical Science
Research Foundation (grant number: SCE154EN), Postdoctoral Scientific
Research Developmental Fund of Heilongjiang Province of China (grant
number: LBH-Q18090).
Conflicts of Interest: The authors have declared that no
conflict of interest exists.