Bacillus cereus is a spore forming and ubiquitous bacterium presents in soil, foods, insect larvae, almost all surfaces and human skin[8–9]. B. cereus has been found in environmental reservoirs such as ventilator equipment, intravascular catheters, and linen. In addition to food poisoning, B. cereus causes a number of systemic and focal infections in both immunologically compromised and immunocompetent individuals. Among those most commonly infected are neonates, especially with indwelling catheters. The spectrum of infections includes fulminant bacteremia, central nervous system(CNS) involvement(meningitis and brain abscesses), to name a few[6]. Research found that a majority of strains(41%) were isolated in newborns, among which 3/4 were premature infants with low birth weight[10]. And, with virulence test of bacterial strain, it is found that the average production of bacterial strain toxin from newborns is low, this suggests that newborn may be particularly sensitive to B. cereus strains, even those with low toxin production, or that other unknown factors may be responsible for newborn infection. The pathogenicity of bacillus cereus is closely related to the production of tissue damaging/reactive exoenzymes. The secretin includes four kinds of hemolysins, three distinct phospholipases, an emesis-in-ducing toxin, and three pore-forming enterotoxin: hemolysin BL (HBL), nonhemolytic enterotoxins (NHE) and cytotoxin K.
Besides, B. cereus can cause severe late-onset hemorrhagic meningoencephalitis in preterm infants. In this study, 7/8 infants had signs and symptoms of meningitis (CSF showed leukocytosis, low glucose, and increased protein), among which 6 patients have shown abnormal expressions in cerebral MRIs. Early and continuous brain sonography is very important for neonates,especially for premature infants༌who are suspected of septicemia or having convulsions. Some research states[11], Serial brain sonography showed that the hemorrhagic meningoencephalitis affects first the white matter and later the basal ganglia and cortex.
According to past research, most bacillus cereus are resistant to penicillin and cephalosporin, but sensitive to aminoglycoside, carbapenem, vancomycin and chloramphenicol[12]. The cases in this research are all responsive to meropenem and vancomycin treatments.
In short, the clinical symptoms of bacillus cereus sepsis in preterm neonates are non-specific, with increased CRP in lab tests, meningitis expressions in CSF examinations, and hemorrhagic meningoencephalitis in cerebral MRI. Meropenem and vancomycin are proven effective in treatment. The limit of the study is the small sample size, therefore more clinical and lab test features cannot be summarized.