The spectrum of acute bacterial meningitis in elderly patients

Table 3 CSF findings, microbiologic features and etiology of acute bacterial meningitis according to age group

	Group I (non-elderly)	Group II (elderly)	RR (95% CI)	P value
	N = 427	N = 208
CSF findings
Protein content, g/l	3.2 (1.5–6.5)	3.8 (1.8–7.3)	----	0.0306
mg/dl	320 (150–650)	380 (180–730)	----	0.0306
CSF/plasma glucose ratio	0.24 (0.07–0.45)	0.22 (0.08–0.42)	----	0.7681
Cells/mm³	1022 (301–2993)	1026 (290–2968)	----	0.7490
Predominance PML ^†	385 (94.4)	183 (91.5)	0.76 (0.52–1.11)	0.2446
Positive CSF Gram stained smear (%)	199 (46.6)	68 (32.7)	0.67 (0.52–0.85)	0.0012
Positive CSF culture (%)	309 (72.4)	141 (67.8)	0.87 (0.68–1.09)	0.2721
Positive blood culture (%)^‡	184 (43.4)	104 (51.5)	1.25 (1.00–1.58)	0.0616
Etiology ^§
Meningococcal (%)	179 (41.9)	24 (11.5)	0.28 (0.19–0.41)	< 0.0001
Pneumococcal (%)	91 (21.3)	59 (28.4)	1.28 (1.01–1.63)	0.0622
Listerial & grampositive bacilli (%)	33 (7.7)	29 (13.9)	1.93 (1.12–2.01)	0.0196
Other Gram-positive cocci (%)	22 (5.1)	13 (6.2)	1.14 (0.73–1.79)	0.7012
Gram-negative bacilli (%)	18 (4.2)	21 (10.1)	1.72 (1.25–2.35)	0.0065
Haemophilus influenzae (%)	9 (2.1)	5 (2.4)	1.09 (0.54–2.23)	0.9685
Mixed (%)	2 (0.5)	2 (1)	1.53 (0.57–4.11)	0.8393
Other	2 (0.5)	1 (0.5)	1.02 (0.20–5.06)	0.5517
Unknown origin (%)	71 (16.5)	54 (25.9)	1.43 (1.12–1.82)	0.0076

Values expressed as median and interquartile range unless otherwise specified. CSF = cerebrospinal fluid. PML polymorphonuclear leukocytes. ^† Differential count performed in 608 patiens. ^‡Blood culture performed in 624 patients. ^§ Gram-positive bacilli: Listeria monocytogenes (60) and Bacillus cereus (2). Gram-positive cocci: Staphylococcus aureus (12), Streptococcus agalactiae (8), Streptococcus viridans (4), Streptococcus pyogenes (3), Enterococcus faecalis (2), Staphylococcus epidermidis (2), Streptococcus anginosus (1), Staphylococcus sp. (1), Group G streptococcus (1), Streptococcus bovis (1). Gram-negative bacilli: Escherichia coli (17), Pseudomonas aeruginosa (8), Pseudomonas sp. (3), Serratia sp. (2), Klebsiella sp. (2), Proteus mirabilis (2), Serratia marcescens (1), Acinetobacter baumanii (1), Bacteroides melaninogenicus (1), and Citrobacter freundii (1), and Enterobacter cloacae (1). Mixed meningitis: Bacteroides intermedius + Streptococcus viridans (1), Enterobacter cloacae + Streptococcus viridans (1), Peptostreptococcus sp. + anaerobic unidentified GNB (1), and Peptostreptococcus sp. + Bacteroides sp. (1). Other: Brucella sp. (2) and Neisseria subflava (1).