Genetic Determinants of Methicillin Resistance and Virulence among Staphylococcus aureus Isolates Recovered from Clinical and Surveillance Cultures in a Brazilian Teaching Hospital

Table 2

Results of univariate and multivariable analysis of molecular predictors for invasiveness among S. aureus strains.

Genes	Univariate				Multivariable
	Clinical cultures (84)	Surveillance cultures (225)	OR (95% CI)	𝑃	OR (95% CI)	𝑃
SCCmec
Absence (reference)	14 (16.7)	75 (33.3)	Reference	—	Reference	—
type II	4 (4.8)	1 (0.4)	21.43 (2.22–206.26)	0.004	10.79 (0.95–122.14)	0.06
type III	59 (70.2)	44 (19.6)	2.19 (1.15–4.18)	0.02	2.19 (1.08–4.45)	0.03
type IV	7 (8.3)	5 (2.2)	7.50 (2.08–27.02)	0.003	5.28 (1.35–20.63)	0.02
Virulence genes
tst	19 (22.6)	28 (12.4)	2.06 (1.08–3.93)	0.03	1.36 (0.65–2.84)	0.41
sea	20 (23.8)	60 (26.7)	0.86 (0.38–1.54)	0.61	1.16 (0.57–2.33)	0.69
seb	22 (26.2)	43 (19.1)	1.50 (0.83–2.71)	0.17	1.64 (0.85–3.16)	0.14
sec1	20 (23.8)	75 (33.3)	0.63 (0.34–1.11)	0.11	0.55 (0.27–1.10)	0.09
eta	2 (2.4)	1 (0.4)	5.46 (0.49–61.06)	0.18	3.57 (1.48–27.46)	0.32
etb	8 (9.5)	4 (1.8)	5.82 (1.70–19.86)	0.002	6.38 (1.48–27.46)	0.01
etd	2 (2.4)	0 (0.0)	Undefined	0.07	Undefined*	0.99
pvl	21 (25.0)	25 (11.1)	2.67 (1.40–5.09)	0.002	2.38 (1.16–4.86)	0.02
ica A	80 (95.2)	220 (97.8)	0.46 (0.12–1.74)	0.26	0.71 (0.14–3.71)	0.69
ica D	84 (100.0)	216 (96.0)	Undefined	0.12	Undefined*	0.99
hla	84 (100.0)	223 (99.1)	Undefined	1.00	Undefined*	0.99
hld	84 (100.0)	225 (100.0)	Undefined	1.00	Not included**	not included

Note: cases are in number (%). Significant results are presented in boldface.
All variables were dichotomic except SCCmec (which was analyzed as a dummy variable, with absence as reference category).
OR: odds ratio. CI: confidence interval.
*CI ranging from zero to infinite. **Not included in the model, due to presence in all analyzed isolates.