The members of this family are part of the normal flora and commonly found in the digestive tracts of humans and animals.

[5] Arterial and venous infarctions are possible because of the bacterial infiltration along the main vessel; exudates within the ventricles and ventriculitis may obstruct the ventricular foramina and result in multicystic hydrocephalus with consequent long-lasting shunting difficulties and necrotizing meningoencephalitis with pneumocephalus has been reported.

[5][6] Macroscopic findings include purulent exudates, opaque leptomeninges (thinning of meninges), pus, and ventriculitis/ ependymitis.

In samples collected from cerebrospinal fluid, C. koseri grows well on any ordinary medium; they produce unpigmented, colorless mucoid colonies.

[5] The differential diagnosis of C. koseri brain abscesses can be confused with other related diseases, so diagnostic imaging is essential to confirm this bacterium.

The significant feature of C. koseri is the necrotic cavity which cannot be misidentified as an earlier ischemic or hemorrhagic insult or other mass lesions; congential/neonatal tumors are uncommon (choroid plexus papillomas, craniopharyngiomas, teratomas); even when they present, they are different from the inflammatory ring of cerebral infection.