The molecular epidemiology and clinical implication of methicillin-resistant Staphylococcus aureus (MRSA) sequence types in pediatric bacteremia: a restrospective observational study, 2016–2021

Table 2 Molecular characteristics of MRSA blood isolates according to the epidemiologic settings across the study periods (n = 74)

	Period 1 (2016–2018) (N = 49)	Period 2 (2019–2021) (N = 25)	P-value	Hospital-onset	Community-onset		P-value
	Period 1 (2016–2018) (N = 49)	Period 2 (2019–2021) (N = 25)		(N = 52)	Healthcare-associated (N = 19)	Community-acquired (N = 3)
SCCmec type
SCCmec I (n = 2)	1 (2.0)	1 (1.0)	> 0.99	1 (1.9)	1 (5.3)	0 (0.0)	0.509
SCCmec II (n = 16)	13 (26.5)	3 (12.0)	0.151	14 (26.9)	2 (10.5)	0 (0.0)	0.125
SCCmec IV (n = 56)	35 (71.4)	21 (84.0)	0.233	37 (71.2)	16 (84.2)	3 (100.0)	0.238
ST groups
ST1 group ^a (n = 4)	3 (6.1)	1 (4.0)	> 0.99	4 (7.7)	0 (0.0)	0 (0.0)	0.311
ST5 group ^b (n = 14)	11 (22.4)	3 (12.0)	0.358	13 (25.0)	1 (5.3)	0 (0.0)	0.052
ST72 group ^c (n = 50)	31 (63.3)	19 (76.0)	0.268	31 (59.6)	17 (89.5)	2 (66.7)	0.031
Others (n = 6)	4 (8.2) ^d	2 (8.0) ^e	> 0.99	4 (7.7) ^f	1 (5.3) ^g	1 (33.3) ^h	> 0.99

Data are presented as numbers (%) of patients
Abbreviations: SCCmec, Staphylococcal cassette chromosome mec; ST, sequence type; SVLs, single locus variants
Notes: ^a ST1 (n = 3) and its SLV (n = 1), including a novel SLV (n = 1)
^b ST5 (n = 9) and its SLVs (n = 5), including ST632 (n = 1) and novel SLV (n = 4). A total of nine ST5 MRSA strains were identified only during period 1 (18.4% [9/20] in period 1 vs. 0% [0/25] in period 2, p = 0.02)
^c ST72 (n = 47) and its single locus variants (SLVs) (n = 3), including ST2084 (n = 2) and a novel SLV (n = 1)
^d Other STs in period 1: ST22 (n = 2), ST30 (n = 1), ST89 (n = 1), and ST1181 (ST8 SLV) (n = 1)
^e Other STs in period 2: ST8 (n = 1), ST 188 (n = 1)
^f Other STs of hospital-onset MRSA: ST22 (n = 2), ST30 (n = 1), ST188 (n = 1), and ST1181 (ST8 SLV) (n = 1)
^g indicates ST89
^h indicates ST8. This single ST8 MRSA isolate with SCCmec type IV was isolated from a community-acquired infection, involving a retropharyngeal abscess extending into the mediastinum

ISSN: 1471-2334