3. Results
In total, 136 sets of blood cultures from 83 cases were SAGpositive.
Of these, five cases were judged to be the result of
contamination. Thus, there were 78 cases in total during the study
period. Patient demographics, clinical characteristics, microbiological
characteristics, therapy and outcomes are summarized in
Table 1. The most common source of infection was hepatobiliaryrelated
(32.1%). Multiple sources of infection were found in three
cases (3.8%). One case had infective endocarditis (IE) complicated
by vertebral osteomyelitis. Another case had sigmoid cancer with
an intra-abdominal abscess extending to the spinal space, then
complicated by bacterial meningitis. The last case had concomitant
hepatic abscess and iliopsoas abscess. IE was seen in four cases;
among these, two cases involved both the mitral and aortic valves.
Two other cases involved the mitral valve alone and two cases
required valve replacement. Central nervous system (CNS) infection
was seen in two cases. One case had a brain abscess and the other
had bacterial meningitis. Among the 71 cases whose sources of
infection were found, the same organisms were identified as being
from a local site in 30 cases (42.2%).
Polymicrobial bacteremia was seen in 28 cases (35.9%). Table 2
shows the microorganisms identified along with the SAG bacteria.
Gastrointestinal flora was the most frequently identified group,
followed by obligate anaerobes, skin and nasopharynx flora and
oral flora. S. constellatus, S. intermedius and S. anginosus were
identified in 27, 19 and 17 cases, respectively. In 15 cases, we could
not identify the organism at the species level (reported as S. milleri
group or SAG). Three cases of S. anginosus and one case of
S. constellatus were identified by MALDI-TOF MS. Surgical treatment
and systemic antibiotics were used in 53% of the cases. The type of surgical treatment performed included endoscopic biliary
drainage (EBD), percutaneous drainage, surgical debridement or
valve replacement. In-hospital mortality was 14.1%. The median
number of days from the onset of bacteremia to death was 29 days
(3e96 days). Among the 11 cases that died during hospitalization,
seven had advanced cancer (gastric cancer, three cases; cholangiocarcinoma,
ureteral cancer, ovarian cancer and hypopharyngeal
cancer, one case each). Among the seven cases with advance
cancer, four of them died during treatment for bacteremia and
three died after treatment completion. Among the four cases
without advanced cancer, one had IE and died after valve replacement.
The other three cases had septic shock, which did not
respond to treatment. In eight cases, mortality was related to SAG
bacteremia. Table 3 shows the sources of infection for the individual
SAG species. S. anginosus and S. intermedius were associated
frequently with hepatobiliary infections. In contrast, the presence
of S. constellatus was more evenly distributed among the various
infection sources.