Table 3.

Characteristics of the Two Major Methicillin-Resistant Staphylococcus aureus Lineages by Sequence-Based Typing and Clonal Grouping Methods

	USA300 lineage				USA100 lineage
	Molecular sequence-based typing method		Clonal grouping method		Molecular sequence-based typing method		Clonal grouping method
Subgroup	MLST ST	spa type	MLST CC	spa CC	MLST ST	spa type	MLST CC	spa CC
Type/clonal group	ST8	t008	CC8	CC008	ST5	t002	CC5	CC002
Number of isolates	105	85	111	111	34	30	42	37
% of all MRSA isolates	61.8%	50.0%	65.3%	65.3%	20.0%	17.6%	24.7%	21.8%
95% CI	54.5–69.1%	42.5–57.5%	58.1–72.5%	58.14–72.46%	14.0–26.0%	11.9–23.3%	18.2–31.2%	15.59–28.01%
PVL
PVL+	95.2%	96.5%	94.7%	95.5%	0.0%	0.0%	0.0%	0.0%
95% CI	91.1–99.3%	92.6–100%	90.5–98.9%	91.64–99.36%	0.0–0.4%	0.0–0.4%	0.0–0.3%	0.0–0.3%
PVL−	4.8%	3.5%	5.3%	4.5%	100.0%	100.0%	100.0%	100.0%
95% CI	0.7–8.9%	−0.4–7.4%	1.1–9.5%	0.64–8.36%	99.6–100.0%	99.6–100.0%	99.7–100.0%	99.7–100.0%
Age group
Children ≤18 years	36.2%	37.6%	36.3%	36.9%	0.0%	0.0%	0.0%	0.0%
95% CI	27.0–45.4%	27.3–47.9%	27.4–45.3%	27.9–45.9%	0.0–0.4%	0.0–0.4%	0.0–0.3%	0.0–0.3%
Adults ≥50 years	64.8%	62.4%	63.7%	63.1%	100.0%	100.0%	100.0%	100.0%
95% CI	54.8–73.2%	51.7–72.3%	54.75–72.65%	54.1–72.1%	99.6–100.0%	99.6–100.0%	99.7–100.0%	99.7–100.0%
Patient setting
Inpatient	13.3%	9.4%	12.4%	12.6%	41.2%	50.0%	47.6%	45.9%
95% CI	6.8–19.8%	3.2–15.6%	6.27–18.53%	6.4–18.8%	24.7–57.8%	32.1–67.9%	32.5–62.7%	29.8–62.0%
Outpatient	86.7%	90.6%	87.6%	87.4%	58.8%	50.0%	52.4%	54.1%
95% CI	80.2–93.2%	84.4–96.8%	81.47–93.73%	81.2–93.6%	42.3–75.3%	32.1–67.9%	37.3–67.5%	38.0–70.2%
Isolate source
Skin	87.6%	85.9%	88.5%	88.3%	50.0%	53.3%	47.6%	48.6%
95% CI	81.3–93.9%	78.5–93.3%	82.57–94.43%	82.3–94.3%	33.2–66.8%	35.5–71.2%	32.5–62.7%	32.5–64.7%
Nonskin	12.4%	14.1%	11.5%	11.7%	50.0%	46.7%	52.4%	51.4%
95% CI	6.1–18.7%	6.7–21.5%	5.57–17.43%	5.7–17.7%	33.2–66.8%	28.9–64.6%	37.3–67.5%	35.3–67.5%

A total of 170 MRSA isolates were analyzed.

PVL, Panton-Valentine Leukocidin genes.