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Dai et al. Neuroimmunol Neuroinflammation 2018;5:28 I http://dx.doi.org/10.20517/2347-8659.2018.09 Page 5 of 8

Two weeks after discharge, we followed up the patient by telephone. His wife told us the lumbar puncture
was performed once more in the rehabilitation facility and he could take care of himself independently. The
laboratory studies of CSF and blood was almost normal [Table 2].

DISCUSSION
There are only about 42 adult cases about Streptococcus gallolyticus meningitis reported according to the
literature. For now, the present case report was the first from the Chinese population. The detail of the
diagnosis and treatment was documented which could provide experience for the subsequent patients of the
CNS infection with Streptococcus gallolyticus.

We think that the gastrointestinal tract was probably the source of Streptococcus gallolyticus in our patient
who had prior gastroenteritis and had the history of moderately differentiated adenocarcinoma of stomach
treated with partial resection together with colonic adenocarcinoma. Many studies have confirmed the fact
that patients with both benign and malignant of gastrointestinal lesions were susceptible to Streptococcus
[1-3]
bovis (S. bovis) bacteremia . A review of 119 cases of S. bovis endocarditis or bacteremia suggested that
[4]
there were 48 patients accompanied with gastrointestinal neoplasms, 22 of which were adenocarcinoma .
[5]
Colonic carcinoma has been reported in up to 50% of patients with S. bovis bacteremia or endocarditis . So,
there is a strong link between Streptococcus gallolyticus infection and bowel disease. Nevertheless, the extent,
nature, and basis of this association are still not completely understood.

According to the literature, the susceptible risk factor for the Streptococcus gallolyticus meningitis was
cacotrophy, immunosuppression, endocarditis, colon carcinoma, strongyloidiasis and bibulosity [6-10] . Among
[11]
the 42 adult patients reported , 43% (18/42) of the patients had the conditions such as immunosuppression,
cancer and alcoholism. Meantime, 33% (14/42) of the patients had the infection with the strongyloidiasis,
63% (15/24) had the colon abnormalities, 8% (5/28) had the endocarditis. Furthermore, endocarditis
has been reported to be caused by S. gallolyticus ssp. gallolyticus more frequently than by S. gallolyticus
ssp. Pasteurianus [12,13] . So, it is necessary to test for strongyloidiasis and do the echocardiography and
colonoscopy for the patients with Streptococcus gallolyticus meningitis. For our patient, it is definitely that
he has the cacotrophy, colon carcinoma, but not the endocarditis. Unfortunately, in our patient, the stool
examination was not performed repeatedly to detect strongyloidiasis.

Even though, the CNS infection has clinical characteristics, such as ardent fever, headache and neck rigidity.
In many patients with CNS infection due to Streptococcus gallolyticus, the presenting differentiated from
each other, as occurred in our patient. It was not until days after admission that our patient developed the
febrile signs. The delayed fever may be the reason of his advanced age , the condition of cacotrophy or the
nosocomial infection.

As we all know, bacterial infection of the CNS has the following characteristics of laboratory examination:
the CSF pressure, WBCs, NEUT% and the protein were high, while the glucose in CSF was reduced. In our
patient, we performed lumbar puncture repeatedly, but the CSF pressure was never higher than normal.
This may be due to differences in individual immune responses. IgG and IgA but no IgM are seen in normal
CSF because IgM has a larger molecular weight. Humoral immune responses often form antigen-antibody
complexes; this reaction is often carried out in blood vessels, leading to severe vasculitis reactions in or
near nerve tissue. It may be the characteristic for Streptococcus gallolyticus meningocephalitis which needs
more clinical data. Meanwhile, we cannot ignore the fact that the cultures plays an important role for the
differentiation of CNS infections. For the 42 patients, the positive incidence was 88% for CSF cultures and
[11]
87% for blood cultures . We performed the blood culture repeatedly, the results were all negative. So we
think that our patient might not be infected through blood but through the gastrointestinal tract.