CSF Profile in Meningitis
The evaluation of the CSF is the definitive diagnostic test in patients with ABM. Microscopic
examination of the CSF by Gram stain provides rapid information regarding the CSF cellular
response as well as the concentration morphology/arrangement of potential neuropathogenic
bacteria. The typical “purulent profile” in the CSF of bacteria causing acute meningitis includes
an early PMN predominance, a decreased CSF glucose, a variabilitated CSF protein, no RBCs,
and a highly elevated CSF lactic acid level (1,3–6). The positivity of the CSF Gram stain depends
on the concentration and type of organism present. The CSF Gram stain is negative half the time
Table 6 Central Nervous System Infections in Normal versus Compromised Hosts
.CNS infection in normal hosts
Usuallyacuteonset of signs and symptoms of meningitis
Singlepathogen
Predictable pathogenbased on epidemiology, patient age, head and neck/CNS anatomic abnormalities, and
host defense defects
Meningitisorencephalitismost frequent manifestation of CNS infection
.CNS infection in compromised hosts
Subacute/indolent onsetof signs and symptoms of CNS infection
Singleorsequential pathogens
Pathogen determined by type of immune defect and degree/duration of immunosuppression
Encephalitis or mass lesions (brain abscess) most common manifestations of CNS infection
Abbreviation: CNS, central nervous system.
Table 7 CNS Pathogens and Disorders Associated with Impaired B-Lymphocyte–Mediated Humoral Deficiency
.Disorders associated with impaired B-lymphocyte function/humoral immunity
Multiple myeloma
B-cell lymphoma
Splenic infarcts
Advanced age
Infiltrative diseases of the spleen
Splenectomy
Waldestro ̈m’s macroglobulinemia
Hereditary immunoglobulin deficiencies
CLL
IgA deficiency
Hyposplenia/decreased splenic function
.Disorders associated with impaired splenic function include:
Hyposplenism of the elderly: Congenital asplenia
Chronic alcoholism: Sickle cell trait or disease
Amyloidosis: Splenic infarcts
Chronic active hepatitis: Splenic malignancies
Fanconi’s syndrome: Systemic mastocytosis
IgA deficiency: Rheumatoid arthritis
Intestinal lymphangiectasia: Systemic necrotizing vasculitis
Myeloproliferative disorders: Thyroiditis
Waldenstrom’s macroglobulinemia: Steroid therapy
Non-Hodgkin’s lymphoma:g-Globulin therapy
Celiac disease: Splenectomy
Regional enteritis: Ulcerative colitis
Sezary syndromeare
CNS pathogens associated with impaired B-Lymphocyte function/humoral immunity
Common Uncommon Rare
Streptococcus pneumoniae Neisseria meningitidis Pseudomonas aeruginosa
Haemophilus influenzae Klebsiella pneumoniae Echovirus
Poliovirus
Abbreviation: CNS, central nervous system.
Meningitis and Its Mimics in Critical Care 143