Table 3. Antimicrobial resistance by risk factor among MRSA isolates comparing data from NHANES 2003–04 and data from Penn State Hershey Medical Center 2009–10.

	NHANES 2003–04						PSHMC 2009–10
	n = 133						n = 88
	Multidrug Resistance (MDR4)			Clindamycin Resistant(CLIR)			Multidrug Resistance (MDR4)			Clindamycin Resistant (CLIR)
	4+ classes of non-susceptibility			high-level resistance			4+ classes of non-susceptibility			high-level resistance
Prevalence	73%			63%			73%			58%
	PR	95% CI	p-value	PR	95% CI	p-value	PR	95% CI	p-value	PR	95% CI	p-value
Gender (male is ref)
Unadjusted	1.00	0.81–1.23	0.98	1.04	0.80–1.35	0.78	0.97	0.74–1.27	0.83	0.98	0.68–1.41	0.90
Adjusted	0.98	0.81–1.20	0.87	1.01	0.79–1.30	0.91	0.93	0.71–1.22	0.60	0.91	0.64–1.32	0.63
Age (18–65 is ref)
Over 65, Unadjusted	1.61	1.24–2.09	<0.001	1.82	1.34–2.48	<0.001	1.16	0.90–1.49	0.25	1.37	0.96–1.95	0.08
Over 65, Adjusted	1.36	1.03–1.78	0.03	1.46	1.03–2.04	0.03	1.20	0.93–1.55	0.17	1.40	0.97–2.02	0.07
Under 18, Unadjusted	1.30	0.97–1.75	0.08	1.17	0.80–1.71	0.41	–			–
Under 18, Adjusted	1.44	1.05–1.97	0.02	1.31	0.89–1.93	0.17	–			–
Hospitalization (>1 year is ref)
Within 1 year, unadjusted	1.30	1.08–1.57	0.005	1.53	1.22–1.92	<0.001	1.22	0.90–1.67	0.20	1.13	0.76–1.68	0.54
Within 1 month, adjusted	1.22	1.00–1.48	0.05	1.36	1.07–2.04	0.01	1.23	0.91–1.66	0.19	1.13	0.77–1.67	0.53
Household Size* (under 2 is ref)
Unadjusted	0.79	0.65–0.96	0.02	0.68	0.53–0.88	0.003	1.05	0.81–1.36	0.71	0.95	0.65–1.39	0.81
Adjusted	0.93	0.73–1.20	0.59	0.76	0.55–1.06	0.10	1.10	0.85–1.41	0.47	1.04	0.70–1.52	0.86

Adjusted models include gender, age, hospitalization, and household size.