Table 4.

Logistic regression analysis with outcome “Gram-negative infection”.

	Univariate analysis	Multivariate analysis
	Odds ratio with 95% confidence intervals	Odds ratio with 95% confidence intervals
Female sex	1.1, 0.9-1.4	n.a.
Median age	1.0, 1.0-1.0	1.0, 1.0-1.0
Serum C-reactive protein level at admission	1.0, 1.0-1.0	n.a.
Immune-compromised	1.3, 1.0-1.6	1.1, 0.9-1.5
- diabetes mellitus	1.6, 1.2-2.1	n.a.
Bacteraemia	0.7, 0.5-1.1	0.7, 0.5-1.1
Presence of osteosynthesis material	1.0, 0.8-1.2	1.0, 0.7-1.4
- total prosthetic joint	0.9, 0.7-1.2	1.0, 0.7-1.5
- nails	1.1, 0.6-2.0	n.a.
- plates	0.8, 0.6-1.3	n.a.
Prior antibiotic use	1.7, 1.2-2.4	2.0, 1.5-2.5
Bone and joint infection	0.7, 0.6-1.0	n.a.
Shoulder infections	0.5, 0.2-0.9	n.a.
Spine infections	0.8, 0.4-1.4	n.a.
Presence of abscess	0.8, 0.6-1.1	n.a.
Polymicrobial infections	5.0, 3.8-6.4	4.9, 3.8-6.3

n.a.= analysis not performed. Only results in bold and italic are statistically significant (two-sided p<0.05)