A prospective cohort study of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus carriage in neonates: the role of maternal carriage and phenotypic and molecular characteristics

Figures & data

Table 1 Multivariate analysis of influencing factors among neonates with Staphylococcus aureus and MRSA carriage in Shenzhen, 2015

Microbial carriage of mothers	S.aureus				MRSA
	RR (95% CI)	aRR (95% CI)^a	P-value^a	NNH(95% CI)^a	RR (95% CI)	aRR (95% CI)^b	P-value^b	NNH(95% CI)^b
Nasal carriage	2.7 (1.6—4.4)	2.8 (1.6—4.8)	<0.001	25 (15—71)	1.7 (0.4—7.5)	2.0 (0.4—8.9)	0.066	138 (—54 to 30)
Vaginal carriage	6.9 (4.1—11.7)	7.1 (4.1 — 12.4)	<0.001	6 (4—11)	2.6 (0.6—11.3)	2.9 (0.6—12.9)	0.067	23 (—21 to 7)
Both nasal and vaginal carriage	10.2 (4.6—22.5)	9.6 (4.2—22.4)	<0.001	8 (4—46)	4.2 (0.6—31.6)	5.5 (0.7—41.9)	0.056	42 (—39 to 12)

Notes: ^aAdjusted for vaginal delivery, frequency of vaginal examination after hospitalization, premature rupture of membranes, and gender of neonates.

b Adjusted for the frequency of vaginal examination after hospitalization.

Abbreviations: MRSA, methicillin-resistant S. aureus; RR, relative risk; aRR, adjusted relative risk; CI, confidence interval; NNH, number needed to harm.

Table 2 Univariate analysis of influencing factors among neonates with Staphylococcus aureus and MRSA carriage in Shenzhen, 2015

Influencing factors	S. aureus (n=60)				MRSA (n=15)
	N	Positive (%)	x^2	P-value	Positive (%)	x^2	P-value
Mothers
Nasal carriage	473	29 (6.1)	16.24	0.00	2 (1.9)	NA	0.21
Vaginal carriage	133	21 (15.8)	NA	0.00	1 (3.2)	NA	0.23
Both nasal and vaginal carriage	60	9 (15.0)	NA	0.00	0 (0)	NA	0.78
Age (>35 years)	114	5 (4.4)	NA	0.49	0 (0)	NA	0.31
Education (below high school)	1287	46 (3.6)	1.57	0.21	12 (0.9)	NA	0.38
Vaginal delivery	1420	54 (3.8)	NA	0.02	13 (0.8)	NA	0.54
Natural impregnation	1809	60 (3.3)	NA	1.00	15 (0.8)	NA	1.00
First pregnancy	606	20 (3.3)	0.002	0.964	4 (0.7)	0.28	0.60
First parturition	924	26 (2.8)	1.24	0.27	6 (0.7)	0.66	0.42
History of abortion	660	18 (2.7)	0.71	0.40	5 (0.8)	0.06	0.81
Frequency of vaginal examination after	533	29 (5.4)	5.97	0.02	10 (1.9)	NA	0.007
hospitalization (≤2)
Vaginitis	150	4 (2.7)	NA	0.81	1 (0.7)	NA	1.00
Premature rupture of membranes	364	6 (1.7)	3.88	0.049	0 (0)	NA	0.05
Days of hospitalization (>3)	1372	40 (2.9)	1.53	0.22	8 (0.6)	NA	0.12
Weeks of pregnancy (<37)	15	1 (6.7)	NA	0.44	0 (0)	NA	1.00
Tobacco use during pregnancy	5	0 (0)	NA	1.00	0 (0)	NA	1.00
Antibiotic use during pregnancy	115	3 (2.6)	NA	0.68	1 (0.9)	NA	1.00
Pet owner	72	3 (4.2)	NA	0.51	1 (1.4)	NA	0.45
Neonates
Male gender	991	40 (4.0)	3.99	0.046	8 (0.8)	0.003	0.96
Birth weight (<2500 g)	52	1 (1.9)	NA	1.00	0 (0)	NA	1.00
Admission to neonatology ward	162	4 (2.5)	NA	1.00	0 (0)	NA	1.00
Apgar 1st minute ≤3	0	0 (0)	NA	NA	0 (0)	NA	NA
Apgar 5th minute ≤6	0	0 (0)	NA	NA	0 (0)	NA	NA

Notes: N indicates the number of patients for whom information was available; n indicates the number of isolates. This was a univariate analysis of influencing factors.

Abbreviations: NA, not applicable; MRSA, methicillin-resistant S. aureus.

Figure 1 Clonal dendrogram and detailed information of Staphylococcus aureus for mother–neonate pairs in Shenzhen, 2015.

Notes: *This pair was concordant (with the same phenotypic and molecular characteristics). MDR, multidrug resistance, resistant to no less than three antibiotic classes.
Abbreviations: M, mother; N, neonate; CC, clonal complex; MLST, multilocus sequence typing; MRSA, methicillin-resistant S. aureus; Pvl, Panton–Valentine leukocidin; Tst, toxic shock syndrome toxin; Eta, exfoliative toxin A; Etb, exfoliative toxin B; SCCmec, staphylococcal cassette chromosome mec; NT, non-typeable.

Table 3 Phenotypic and toxin genetic characteristics of Staphylococcus aureus and MRSA isolates between neonates and mothers (nares and vagina) in Shenzhen, 2015, n (%)

Characteristics	S. aureus					MRSA
	Neonates(n=60)	Mothers,nasal(n=473)	Mothers,vaginal(n=133)	P-value^a	P-value^b	Neonates(n=15)	Mothers,nasal(n=104)	Mothers,vaginal(n=31)	P-value^a	P-value^b
Phenotypic (resistant)
EM	28 (46.7)	224 (47.4)	67 (50.4)	0.920	0.633	13 (86.7)	80 (76.9)	24 (77.4)	0.518	0.696
PCN	56 (93.3)	433 (91.5)	123 (92.5)	0.635	1.000	13 (86.7)	101 (97.1)	29 (93.6)	0.119	0.587
GM	5 (8.3)	31 (6.6)	11 (8.3)	0.585	1.000	2 (13.3)	6 (5.8)	5 (16.1)	0.265	1.000
CM	17 (28.3)	163 (34.5)	55 (41.4)	0.344	0.083	10 (66.7)	60 (57.7)	20 (64.5)	0.509	0.886
RFP	5 (8.3)	37 (7.8)	3 (2.3)	0.802	0.110	3 (20.0)	25 (24.0)	2 (6.5)	1.000	0.311
LZD	2 (3.3)	16 (3.4)	5 (3.8)	1.000	1.000	1 (6.7)	5 (4.8)	3 (9.7)	0.563	1.000
MXF	3 (5.0)	40 (8.5)	18 (13.5)	0.457	0.078	3 (20.0)	6 (5.8)	9 (29.0)	0.086	0.723
TMP/SMX	8 (13.3)	40 (8.5)	I9 (14.3)	0.214	0.860	4 (26.7)	13 (12.5)	6 (19.4)	0.227	0.706
TEC	12 (20.0)	227 (48.0)	108 (81.2)	0.000	0.000	4 (26.7)	54 (51.9)	23 (74.2)	0.067	0.002
TOB	11 (18.3)	109 (23.0)	36 (27.1)	0.410	0.191	2 (13.3)	21 (20.2)	12 (38.7)	0.733	0.099
MDR	23 (38.3)	244 (51.6)	86 (64.7)	0.053	0.001	12 (80.0)	83 (79.8)	26 (83.9)	1.000	1.000
Toxin genetic (positive)
Pvl	3 (5.0)	22 (4.7)	3 (2.3)	0.753	0.377	0 (0)	13 (12.5)	2 (6.5)	0.368	1.000
Tst	2 (3.3)	11 (2.3)	3 (2.3)	0.648	0.647	0 (0)	3 (2.9)	1 (3.2)	1.000	1.000
Eta	7 (11.7)	13 (2.8)	4 (3.0)	0.004	0.037	2 (13.3)	2 (1.9)	1 (3.2)	0.077	0.244
Etb	0 (0)	1 (0.2)	0 (0)	1.000	NA	0 (0)	1 (1.0)	0 (0)	1.000	NA

Notes: ^aP-value was calculated as the proportion of S. aureus/MRSA isolates between neonates and mothers’ nares.

b P-value was calculated as the proportion of S. aureus/MRSA isolates between neonates and mothers’ vaginas. MDR, multidrug resistance, resistant to no less than three antibiotic classes.

Abbreviations: MRSA, methicillin-resistant S. aureus; n, number of isolates; EM, erythromycin; PCN, penicillin; GM, gentamicin; CM, clindamycin; RFP, rifampicin; LZD, linezolid; MXF, moxifloxacin; TEC, teicoplanin; TOB, tobramycin; TMP/SMX, trimethoprim-sulfamethoxazole; Pvl, Panton–Valentine leukocidin; Tst, toxic shock syndrome toxin; Eta, exfoliative toxin A; Etb, exfoliative toxin B; NA, not applicable.

Figure 2 Distribution of CCs by neonates and mothers.

Notes: Singleton refers to STs that could not be assigned to any group in Shenzhen, 2015. (A) Distribution of CCs on Staphylococcus aureus isolates by neonates and mothers. (B) Distribution of CCs on MRSA isolates by neonates and mothers.
Abbreviations: CC, clonal complex; ST, sequence type; MRSA, methicillin-resistant S. aureus.