Pediatric Staphylococcus aureus Isolate Genotypes and Infections from the Dawn of the Community-Associated Methicillin-Resistant S. aureus Epidemic Era in Chicago, 1994 to 1997

Michael Z. David; Mary Ellen Acree; Julia J. Sieth; Dave J. Boxrud; Ginette Dobbins; Ruth Lynfield; Susan Boyle-Vavra; Robert S. Daum

doi:10.1128/JCM.00096-15

DOI: 10.1128/JCM.00096-15

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FIG 1
Dendrogram showing the PFGE gel result for the sole USA300 MRSA isolate obtained in this study (isolate 111395F, which belonged to ST8, carried SCCmec type II, did not carry the PVL gene or arcA, and had spa type t064) as well as those for control USA300 and USA500 strains.

TABLE 1

Molecular characterization of 75 methicillin-susceptible Staphylococcus aureus isolates, University of Chicago Medical Center, 1995 to 1997^a

MLST	Total no. of isolates (%)	PVL	Yr of isolation	No. of isolates
1	2 (2.7)	−	1996	1
1	2 (2.7)	+	1996	1
5	10 (13.3)	−	1995	2
		−	1996	7
		−	1997	1
8	4 (5.3)	−	1996	3
8	4 (5.3)	−	1995	1
15	12 (16)	−	1995	2
		−	1996	7
		−	1997	3
25	3 (4)	−	1995	1
		−	1996	1
		−	1997	1
30	16 (21.3)	−	1995	2
		−	1996	7
		−	1997	6
		+	1996	1
39	1 (1.3)	−	1996	1
45	13 (17.3)	−	1995	3
		−	1996	9
		−	1997	1
51	1 (1.3)	−	1996	1
59	4 (5.3)	−	1995	1
59	4 (5.3)	−	1996	3
96	1 (1.3)	−	1997	1
101	1 (1.3)	−	1996	1
109	3 (4)	−	1996	2
109	3 (4)	−	1995	1
121	1 (1.3)	+	1995	1
435	1 (1.3)	−	1996	1
474	1 (1.3)	−	1996	1
508	1 (1.3)	−	1995	1
Total	75 (100)			75

↵a All isolates were negative for opp3 and arcA, markers for the arginine catabolic mobile element (ACME), by PCR. MLST, multilocus sequence typing; PVL, Panton-Valentine leukocidin.

TABLE 2

Molecular characterization of 30 methicillin-resistant Staphylococcus aureus isolates, University of Chicago Medical Center, 1994 to 1997^a

PFGE type (80% similarity cutoff)^b	Total no. of isolates (%)	MLST	SCCmec type	Presence of gene			Yr of acquisition	spa type^c	No. of isolates
PFGE type (80% similarity cutoff)^b	Total no. of isolates (%)	MLST	SCCmec type	PVL	arcA	opp3	Yr of acquisition	spa type^c	No. of isolates
NT	2 (6.7)	8	IV	+	−	−	1997	NA	1
NT	2 (6.7)	12	IV	−	−	−	1997	NA	1
USA100	2 (6.7)	5	II	−	−	−	1995	NA	1
USA100	2 (6.7)	5	II	−	−	−	1997	NA	1
USA200	3 (10.0)	5	II	−	−	−	1994	NA	1
		5	II	−	−	−	1995	NA	1
		36	II	−	−	−	1996	NA	1
USA300	1 (3.3)	8	II	−	−	−	1995	t064	1
USA400	13 (43.3)	1	IV	+	−	−	1996	NA	3
		1	IV	+	−	−	1997	NA	5
		1	IV	−	−	−	1995	NA	2
		1	IV	−	−	−	1997	NA	1
		8	IV	+	−	−	1997	NA	1
		8	IV	−	−	−	1994	NA	1
USA500	8 (26.7)	8	IV	+	−	−	1996	t064	6
USA500	8 (26.7)	8	IV	+	−	−	1997	t064	2
USA600	1 (3.3)	45	IV	−	−	−	1997	NA	1
Total	30 (100)								30

↵a PFGE, pulsed-field gel electrophoresis; MLST, multilocus sequence typing; PVL, Panton-Valentine leukocidin; arcA and opp3, markers for the arginine catabolic mobile element (ACME) detected by PCR.
↵b The isolates fell within the standard criteria used for inclusion in the USA typing scheme (at least 80% similarity to the pattern of a particular USA type). NT, nontypeable; the isolate(s) indicated did not fall into one of the known USA type clonal groups. All isolates showed banding patterns by PFGE. If an isolate had >80% pattern similarity with multiple USA types, the USA type that had the highest percentage of similarity was designated as the type.
↵c Only USA300 and USA500 isolates were genotyped using spa typing. NA, not applicable (testing was not conducted).

TABLE 3

Demographic and clinical characteristics of patients with methicillin-resistant Staphylococcus aureus and methicillin-susceptible S. aureus infections at the University of Chicago Medical Center, 1994 to 1997

Characteristic	No. (%) of patients with:		P
Characteristic	MRSA (n = 30)	MSSA (n = 75)	P
Clinical syndrome			0.5
Bacteremia, endocarditis, or sepsis	8 (27)	14 (19)
Osteomyelitis or septic arthritis	0	4 (5)
Respiratory	3 (10)	2 (3)
Skin and soft tissue infection	16 (53)	36 (48)
Urinary tract infection	0	1 (1)
Colonization	3 (10)	14 (19)
Other^a	0	2 (3)
Age group (yr)			0.2
<1	9 (30)	26 (35)
1–2	7 (23)	8 (11)
3–5	2 (7)	13 (17)
6–12	9 (30)	15 (20)
13–18	3 (10)	13 (17)
Gender			0.3
Male	14 (47)	43 (57)
Female	16 (53)	32 (43)
Race			0.1
African-American	23 (77)	42 (56)
White	3 (10)	15 (20)
Unknown or other	4 (13)	18 (24)
Type of insurance			0.5
Public assistance	23 (77)	49 (65)
Private	6 (20)	24 (32)
Uninsured	1 (3)	2 (3)
Presence of risk factors for HA-MRSA
Inpatient culture obtained >48 h after admission	13 (46)	31 (41)	0.6
Hospital stay, past yr	8 (27)	29 (39)	0.2
Surgery, past yr	5 (17)	26 (35)	0.07
Hemodialysis, past yr	0	0	NA^c
Indwelling catheter	9 (30)	30 (40)	0.9
Stay in long-term-care facility, past yr	0	3 (4)	0.6
Location of care^b			0.1
Intensive care units	9 (30)	32 (43)
Other inpatient units	13 (43)	26 (35)
Emergency department	4 (13)	6 (8)
Outpatient	2 (7)	11 (15)
Unknown	2 (7)	0
CDC criteria for infection type			0.2
CA	12 (40)	21 (28)
HO	13 (45)	31 (41)
HACO	4 (14)	23 (31)
Previous MRSA isolation, UCMC laboratory report	5 (17)	2 (3)	0.02