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Table 5 Overview of diagnostically relevant routine parameters in acute bacterial meningitis (BM) and frequency of “typical” and “atypical” changes depending on the bacterial pathogen

From: S1 guidelines “lumbar puncture and cerebrospinal fluid analysis” (abridged and translated version)

Parameter Diagnostic (first) LP Remarks / Special features
Cell count (CC) / μLμL „typical "CC ≥1000: ca. 80%
Mean (SD): 7753 (14736)
CC 100–999: 14%
CC <  100: 7%
[16] Cave „apurulent BM": do not discontinue antibiotic treatment when CC is low, but CSF lactate or protein values are high!
S. pneumoniae Median (IQR): 1842 (291–4419)
CC > 999: 75.8-78%
CC < 100: 17-19.3%
CC < 10: 5%
([17, 136]) (n = 153) [24];
N. meningitidis Median (IQR): 5328 (1590–12.433)
CC > 999: 80-82%
CC 100–999: 6.5-11%;
CC < 100: 9-11.6%,
initial CSF normal: 1.7% (CC ≤5/μL, TP ≤0.50 g/l und Glucose ratio CSF / blood ≥0.40)
[68] (n = 258) [24];
L. monocytogenes Median (IQR): 680 (291–1545)
CC < 100: 11%
[99] (n = 30 + 62)
H. influenzae b Median (Min-Max): 1470 (0–11,400)
CC > 999: 92.9%;
CC 100-999: 7%
CC < 100: 0%
[14] (n = 11)
[24]
 B-streptococci Median (Min-Max): 1230 (0-80,000)
CC „normal": 6%
[57] (n = 242)
 Newborn meningitis CC ≤ 3: 10% [54]
Differential Cell count „typical "= granulocytic  
S. pneumoniae ≤20% Granulocytes: 5.9% [24]
N. meningitidis ≤20% Granulocytes: 8.2% [24]
L. monocytogenes < 50% Granulocytes: 26% [99]
H. influenzae b ≤20% Granulocytes: 4.3% [24]
 B-Streptococcus Median (Min-Max): 87 (0-100) % [57]
Total protein (TP) in mg/l „typical "TP > 1000
Mean (SD): 4900 (4500)
[16]
S. pneumoniae Median (IQR): 2700 mg/l (1400–5800) [136]
N. meningitidis Median (IQR): 4500 mg/l (2200–7000) [68]
L. monocytogenes Median (IQR): 2500 mg/l (1760–3650) [99]
H. influenzae b Median: 1800 mg/l [14](n = 11)
 B streptococci Median (Min-Max): 2480 mg/l (200-16,000) [57]
 Newborn meningitis TP < 400: 0%
TP 410-1200: 24%
TP >  1200: 76%,
[54]
Lactate (mmol/L) „typical "Lactate ≥3.5 l
diverging reference ranges, recommended cut-off: 3.9 mmol/L (=35 mg/dl)
Man (SD): 16.51 (6.1)
Median (IQR): 9.9 (6.8-12.9) mmol/L
[1, 97, 152]
 DD bacterial versus viral meningitis Lactate as sensitive differentiation criterion (Meta-analysis: [79, 152])
Sensitivity untreated BM: 98%
Sensitivity after preantibiosis: 49%
Cave: Lactate increase also found in status epilepticus, cerebral infarction, ICB, Tumor, Herpes encephalitis
[152]
Macroscopy / Gram staining positive 63-72%
no preantibiosis: 63%
with preantibiosis: 62%
[24] (n = 667);
[130]
S. pneumoniae positive: 85.2% [24] (n = 162)
N. meningitidis positive: 72.5-89% [24] (n = 356) [68]; (n = 244)
L. monocytogenes positive: 37% [99]
H. influenzae b positive: 83.3% [24] (n = 72)
CSF culture Positive no preantibiosis: 65.8-88%,
positive with preantibiosis: 61.4-70%
[24, 130]
S. pneumoniae positive: 75-87% [96] (n = 83) [24];
N. meningitidis positive: 79.5% [24]
H. influenzae b positive: 50% [24]
Blood culture positive no preantibiosis: 66%
positive with preantibiosis: 48%
[16, 130]
S. pneumoniae positive: 42.6-67% [24, 96] (n = 76) [136]; (n = 186)
N. meningitidis positive: 12.6 -57% [24, 68] (n = 227)
L. monocytogenes positive: 61% [99]
H. influenzae b positive: 50% [24]
 Newborn meningitis positive: 62% [54] (n = 92)