Role of cerebrospinal fluid lactate in diagnosing meningitis in critically ill patients

Table 1 Basic characteristics, clinical parameters and hospital course

Patient parameters	Overall (n = 71), %	Meningitis group (n = 23) , %	Non-Meningitis Group (n = 48), %	P value
Age, yr	58.1 ± 16	57.8 ± 15.4	58.9 ± 17.3	0.820
Males	23 (32.4)	10 (43.5)	13 (27.1)	0.167
Clinical parameters
Headache	25 (35.2)	11 (47.8)	14 (29.2)	0.123
Seizures	46 (64.8)	17 (73.9)	29 (60.4)	0.265
Fever	50 (70.4)	16 (69.6)	34 (70.8)	0.871
Altered sensorium	70 (98.6)	23 (100)	47 (97.9)	0.486
Photophobia	5 (7)	3 (13)	2 (4)	0.171
Coma	24 (33.8)	9 (39.1)	15 (31.3)	0.511
Antibiotic exposure before CSF analysis	65 (91.5)	22 (95.7)	43 (89.6)	0.39
Traumatic brain injury	2 (3)	0 (0)	2 (4)	0.321
Neurosurgical intervention	4 (5.6)	3 (13)	1 (2)	0.061
Neurosurgical device in-situ	4 (5.6)	3 (13)	1 (2)	0.061
Glasgow coma scale	9.5 ± 4	9 ± 4	9.7 ± 4	0.508
Neck stiffness	4 (5.6)	4 (17.4)	0 (0)	0.003a
Focal neurological deficit	14 (19.7)	5 (21.7)	9 (18.8)	0.767
Length of stay in hospital	21.1 ± 16	21.9 ± 8.9	21 ± 18.2	0.053
Length of stay in ICU	10.4 + 8.9	12.1 ± 6.3	9.6 ± 9.8	0.005a
Need for any surgical intervention	20 (28.2)	10 (43.5)	10 (20.8)	0.047a
Need for invasive mechanical ventilation	27 (38)	13 (56.5)	14 (29.2)	0.026a
ICU mortality	20 (28.2)	10 (43.5)	10 (20.8)	0.047a

^aP value statistically significant.

CSF: Cerebrospinal fluid; ICU: Intensive care unit.

Table 2 Comparison of cerebrospinal fluid analysis between meningitis and non-meningitis groups

CSF parameters	Meningitis group (n = 23)	Non-meningitis group (n = 48)	P value
TLC (mean ± SD)	1223.4 ± 2611	8.1 ± 12.6	< 0.001a
Protein (mean ± SD)	177.1 ± 204.2	69.3 ± 61.5	0.002a
Sugar mg/dL (mean ± SD)	90.1 ± 98.4	102.1 ± 41	0.011a
Lactate levels mg/dL (mean ± SD)	60 ± 43.9	23.6 ± 11.1	< 0.001a
Lactate levels mmol/L (mean ± SD)	6.6 ± 4.8	2.6 ± 1.2	< 0.001a
Positive CSF cultures	17 (74)	0 (0)	< 0.001a
Positive meningo-encephalitis panel	7 (30)	0 (0)	0.001a
Positive CSF cultures or meningo-encephalitis panel	23 (100)	0 (0)	< 0.001a

^aP value statistically significant.

CSF: Cerebrospinal fluid; SD: Standard deviation.

Table 3 Comparison of various cerebrospinal fluid parameters for diagnosing meningitis

CSF Parameters	Cut-off	Sensitivity, %	Specificity, %	NPV, %	PPV, %	Accuracy, %	AUC	CI	P value
TLC (Cell/mm3)	> 55	73.9	100	100	88.9	91.5	0.92	0.84-1	< 0.001a
Lactate levels (mmol/L)	> 2.7	82.6	72.9	59.4	89.7	76.1	0.81	0.7-0.9	< 0.001a
Protein (mg/dL)	> 104.4	56.5	87.5	68.4	80.8	77.5	0.73	0.6-0.9	0.002a
Sugar (mg/dL)	> 63	56.5	83.3	61.9	80.0	74.6	0.7	0.6-0.9	0.006a

^aP value statistically significant.

CSF: Cerebrospinal fluid; AUC: Area under the curve; CI: Confidence interval; NPV: Negative predictive value; PPV: Positive predictive value; TLC: Total leucocyte count.

Table 4 Etiological causes of patients in meningitis and non-meningitis groups

Meningitis group (n = 23), %
Bacterial (n = 12)	Streptococcus pyogenes	5 (41.7)
	Staphylococcus aureus	2 (16.7)
	Haemophilus influenzae	2 (16.7)
	Enterococcus faecium	2 (16.7)
	Escherichia coli	1 (8.4)
Viral (n = 6)	Varicella zoster virus	3 (27.3)
	Herpes simplex virus	2 (18.2)
	Measles virus	1 (9.1)
Fungal (n = 2)	Candida tropicalis	1 (9.1)
	Cryptococcus neoformans	1 (9.1)
Tubercular (n = 3)	Mycobacterium tuberculosis complex	3 (27.3)
Non-meningitis group (n = 48)
Septic and metabolic encephalopathy		34 (70.8)
Hypoxic brain injury		3 (6.3)
Guillain barre syndrome		2 (4.2)
Autoimmune encephalitis		2 (4.2)
Metastatic brain involvement		2 (4.2)
Post-ictal confusion		2 (2.1)
Hypoglycaemic coma		1 (2.1)
Demyelinating disorder		1 (2.1)
Unknown		1 (2.1)