Table 1.

Incidence of Group B Streptococcus by capsular type /3 weeks/100 persons, by selected sexual behaviors in the previous 3 weeks (participants followed in 3 week intervals). 129 female and 128 male freshmen college students living in a single dormitory

Characteristic	Person intervals	% Capsular type la or lb	% Capsular type V	% Non la, lb or V capsular types	% All capsular types combined
Gender
Male	340	2.9	3.2	2.7	8.8
Female	256	3.5	3.9	3.9	11.3
Sex in last 3 weeks
No	377	2.9	2.1	1.9	6.9
Yes	216	3.7	6.0	5.6	15.3
X² p-value		0.60	0.01	0.01	0.001
Frequency of vaginal intercourse previous 3 weeks
None	447	2.9	2.7	1.8	7.4
1 to 2	51	7.8	2.0	5.9	15.7
3 to 9	76	1.3	7.9	7.9	17.1
10 or more	17	5.9	5.9	11.8	23.5
Test for trend^*		0.75	0.10	0.001	0.002
Frequency of active oral sex in past 3 weeks
None	439	3.6	2.3	2.5	8.4
1 to 2	93	1.1	8.6	4.3	14.0
3 to 9	55	1.8	5.5	5.5	12.7
10 or more	4	25.0	0	25.0	50.0
Test for trend^*		0.39	0.23	0.009	0.005
Frequency of passive oral sex in past 3 weeks
None	435	3.5	2.1	2.3	7.8
1 to 2	88	1.1	11.4	4.6	17.1
3 to 9	61	3.3	3.3	6.6	13.1
10 or more	6	16.7	0	16.7	33.3
Test for trend^*		0.27	0.48	0.007	0.008
Maximum frequency of all sex acts in past 3 weeks
None	395	2.8	2.5	1.7	7.1
1 to 2	84	4.8	3.6	3.6	7.1
3 to 9	93	2.2	7.5	7.5	17.2
10 or more	20	10.0	5.0	10.0	25.0
Test for trend^*		0.17	0.12	0.003	0.0004
Number of sex partners in last 3 weeks
None	378	2.9	2.4	1.9	7.1
1	191	3.7	6.3	5.2	15.2
2	11	9.1	0	9.1	18.2
3 or more	12	0	0	8.3	8.3
Trend test ^*		0.71	0.27	0.01	0.02
Number of sex partners in past 12 months
None	191	2.1	1.6	1.6	5.2
1	219	3.2	4.6	3.2	11.0
2	85	2.4	5.9	2.4	10.6
3 or more	100	6.0	3.0	7.0	16.0
Test for trend^*		0.12	0.32	0.03	0.005
Used a condom past 3 weeks
No	499	3.4	2.8	2.8	9.0
Yes	94	2.1	7.5	5.3	14.9
X² p-value		0.52	0.03	0.20	0.08
Sex with new partner in previous 3 weeks?
No sex	380	3.9	6.1	1.8	6.8
Sex old partner	164	5.8	6.1	2.1	15.9
Sex new partner	52	3.9	3.7	2.9	13.5
X² p-value		0.60	0.03	0.05	0.005

P value for the Mantel-Haenszel Chi-square test for trend