Predictive Role of Targeted, Active Surveillance Cultures for Detection of Methicillin-Resistant Staphylococcus aureus

Figures & data

Table 1 Epidemiological Characteristics of Study Population (n = 1345, Median Age = 23 Years, SD = 24.61)

Demographic Data
Age	Age Distribution	No. of Positive Samples (%)
	≤1 Year	356 (18.7)
	>1 to ≤10 Y	344 (18)
	>10 to ≤ 20 Y	176 (9.2)
	>20 to ≤30 Y	232 (12.2)
	>30 to ≤40 Y	253 (13.3)
	>40 to ≥50 Y	160 (8.4)
	>50 Y	385 (20.2)
Gender	Male (%)	Female (%)
	696 (51.7)	649 (48.3)
Area	Location	No. of Positive (%)
	Inpatient	556 (41.3)
	Outpatient	84 (6.2)
	Critical care units	256 (19)
	Emergency department	437 (32.5)
	Dialysis units	12 (0.9)

Table 2 Prediction of Different Screening Sites for Culture-Based MRSA Detection

Screening Site/s	No. of Positive Samples	Sensitivity % (95% CI)	NPV % (95% CI)	NND*	CUI*	Missed Isolation Days (95% CI)
Nasal	899	66.8 (64–69)	90.1 (89–91)	3.3	0.901	277.9 (253–294)
Throat	619	46.0 (43–49)	84.8 (84–85)	5.4	0.848	441.5 (416–466)
Axilla	101	7.5 (6–9)	76.4 (76–77)	9.2	0.764	760.3 (743–768)
Groin	181	13.5 (12–15)	77.6 (77–78)	8.7	0.776	711.2 (694–719)
Nasal and throat	1253	93.2 (91–94)	97.8 (97–98)	1.4	0.978	57.2 (49–73)
Nasal and axilla	946	70.3 (68–73)	91.0 (90–92)	1.9	0.91	245.2 (220–261)
Nasal and groin	979	72.8 (70–75)	91.7 (90–92)	1.8	0.92	220.7 (204–245)
Groin and axilla	250	18.6 (17–21)	78.7 (78–79)	6.5	0.79	662.2 (646–679)
Groin and throat	741	55.1 (52–58)	87.0 (86–88)	4.3	0.87	367.9 (343–392)
Throat and axilla	677	50.3 (48–53)	85.8 (85–86)	4.9	0.86	408.8 (384–425)
Nasal, throat and axilla	1304	97.0 (92–99)	99.0 (98–99)	1.2	0.99	24.5 (21–29)
Nasal, throat and groin	1343	99.9 (94–100)	99.9 (99–100)	1.1	1	1.9 (1–3)
Nasal, throat, groin and axilla	1345	100 (98–100)	100 (NA)	1	1	–

Notes: MRSA colonized patients were defined as those colonized in one or more of these sampling sites (nose, throat, axilla or groin). *NND = 1/[Sensitivity – (1 – Specificity)], where the smaller the NND, the more useful the assay. CUI+: Clinical Utility Index interpreted: < 0.2 poor, > 0.2 < 0.4 fair, > 0.4 < 0.6 moderate, > 0.6 < 0.8 good and > 0.8 < 1 excellent.

Abbreviations: NPV, negative predictive value; NND, number needed to diagnose; CUI, clinical utility index.

Figure 1 Trend of antimicrobial resistance among MRSA screening cultures.