Incidence of invasive Group B Streptococcus (iGBS) infections and the factors associated with iGBS mortality in adults during 2013–2017: a retrospective study at Thailand’s largest national tertiary referral center

Figures & data

Figure 1. Number of cases by age category for each year from 2013 to 2017.

Table 1. Demographic and clinical characteristics of patients with invasive Group B Streptococcus (iGBS) diseases compared between those with and without bacteraemia.

Characteristics	All patients	Bacteraemia	No bacteraemia	p-Value
	(n = 224)	(n = 170)	(n = 54)
Age (years)	63 (53.3–73.7)	64.5 (52–75)	59.5 (54–67)	.778
Age ≥65 years	101 (45.1%)	85 (50.0%)	16 (29.6%)	.009
Female gender	118 (52.7%)	93 (54.7%)	25 (46.3%)	.281
Pregnant/postpartum within 30 days	4 (1.8%)	4 (4.3%)	0 (0.0%)	.737
Comorbid disease	178 (79.5%)	139 (81.8%)	39 (72.2%)	.130
Diabetes mellitus	87 (38.8%)	61 (35.9%)	26 (48.1%)	.107
Solid malignancy	42 (18.8%)	38 (22.4%)	4 (7.4%)	.014
Heart disease	28 (12.5%)	26 (15.3%)	2 (3.7%)	.025
Chronic kidney disease	25 (11.2%)	22 (12.9%)	3 (5.6%)	.133
Chronic liver disease	19 (8.5%)	17 (10.0%)	2 (3.7%)	.259
Neurological disorder	15 (6.7%)	15 (8.8%)	0 (0.0%)	.025
Chronic lung disease	6 (2.7%)	5 (2.9%)	1 (1.9%)	1.000
Immunosuppressive agent	5 (2.2%)	5 (2.9%)	0 (0.0%)	.34
Autoimmune disease	3 (1.3%)	2 (1.2%)	1 (1.9%)	.565
Hematologic malignancy	2 (0.9%)	2 (1.2%)	0 (0.0%)	1.000
Others	75 (33.4%)	17 (10.0)	0 (0.0%)
Clinical manifestations^a
Skin and soft tissue infection	69 (30.8%)	35 (20.6%)	34 (63.0%)	<.001
Septic arthritis	48 (21.4%)	36 (21.2%)	12 (22.2%)	.87
Bacteraemia without focus	47 (21.0%)	47 (27.6%)	0 (0.0%)	<.001
Meningitis	16 (7.1%)	16 (9.4%)	0 (0.0%)	.014
Pneumonia	14 (6.2%)	14 (8.2%)	0 (0.0%)	.025
Osteomyelitis	13 (5.8%)	2 (1.2%)	11 (20.4%)	<.001
Infective endocarditis	9 (4.0%)	9 (5.3%)	0 (0.0%)	.118
Eye infection	2 (0.9%)	2 (1.2%)	0 (0.0%)	1.000
Urinary tract infection	2 (0.9%)	2 (1.2%)	0 (0.0%)	1.000
Endometritis	1 (0.4%)	1 (0.6%)	0 (0.0%)	1.000
Chorioamnionitis	1 (0.4%)	1 (0.6%)	0 (0.0%)	1.000
Others	25 (11.1%)	25 (14.7%)	0 (0.0%)	.994
Polymicrobial infections	45 (20.1%)	20 (11.8%)	25 (46.3%)	<.001
Duration of treatment (days)^b	14 (14–42)	14 (10–28.7)	55 (7–405)	<.001
Length of hospital stay among hospital inpatients (days)^c	17 (1–344)	14 (2–344)	15.5 (1–118)	.846
Morbidities	88 (39.3%)	82 (48.2%)	6 (11.1%)	<.001
Mortality^c	23 (11.2%)	22 (14.4%)	1 (1.9%)	.011

Data reported as median and interquartile range (IQR) or number and percentage.

Bold p-values indicate statistical significance.

^aSome patients had more than one clinical syndrome.

^bExcluded 16 cases: 14 referral cases (12 cases in the bacteraemia group, and 2 cases in the no bacteraemia group) and 2 cases against advice.

^cCalculated from 206 patients (excluded 18 cases: 15 referral cases and 3 against advice, of which 17 were in the bacteraemia group and 1 was in the no bacteraemia group).

Figure 2. (A) Empirical antibiotic therapy and (B) definite antibiotic therapy of invasive Group B Streptococcus (iGBS) disease categorised by clinical manifestation. SSTIs: skin and soft tissue infections; Amox-clav: Amoxicillin/clavulanic acid; PGS: Penicillin G Sodium; Pip/taz: Piperacillin/tazobactam.

Table 2. Demographic and clinical characteristics compared between patients that survived and that died within 30 days (n = 206^a).

Characteristics	Survived	Deceased	p-Value
	(n = 183)	(n = 23)
Age (years)	63 (54–72)	76 (61–82)	.028
Age ≥65 years	79 (43.2%)	17 (73.9%)	.006
Female gender	101 (55.2%)	9 (39.1%)	.146
Comorbid disease	145 (79.2%)	20 (87.0%)	.008
Diabetes mellitus	73 (39.9%)	10 (43.5%)	.741
Solid malignancy	34 (18.6%)	7 (30.4%)	.180
Heart disease	26 (14.2%)	0 (0.0%)	.053
Chronic kidney disease	18 (9.8%)	6 (26.1%)	.022
Chronic liver disease	15 (8.2%)	3 (13.0%)	.438
Neurological disorder	11 (6.0%)	2 (8.7%)	.618
Chronic lung disease	6 (3.3%)	0 (0.0%)	.378
Immunosuppressive agent	3 (1.6%)	1 (4.3%)	.375
Autoimmune disease	3 (1.6%)	0 (0.0%)	.536
Hematologic malignancy	1 (0.5%)	1 (4.3%)	.080
Bedridden state	7 (3.8%)	3 (13.0%)	.053
Bacteraemia	131 (71.6%)	22 (95.7%)	.013
Clinical manifestations
Skin and soft tissue infection	61 (33.3%)	3 (13.0%)	.047
Primary bacteraemia	36 (19.7%)	7 (30.4%)	.231
Septic arthritis	43 (23.5%)	2 (8.7%)	.105
Meningitis	10 (5.5%)	3 (13.0%)	.159
Pneumonia	4 (2.2%)	9 (39.1%)	<.001
Osteomyelitis	13 (7.1%)	0 (0.0%)	.187
Infective endocarditis	9 (4.9%)	0 (0.0%)	.277
Eye infection	2 (1.1%)	0 (0.0%)	.614
Urinary tract infection	0 (0.0%)	1 (4.3%)	.005
Endometritis	1 (0.5%)	0 (0.0%)	.722
Chorioamnionitis	1 (0.5%)	0 (0.0%)	.722
Polymicrobial infections	35 (19.1%)	7 (30.4%)	.205
Morbidities	57 (31.1%)	23 (100%)	<.001
Shock	17 (9.3%)	13 (56.5%)
Renal failure	17 (9.3%)	4 (17.4%)
Respiratory failure	5 (2.7%)	4 (17.4%)
Others	18 (9.8%)	2 (20.9%)
Duration of treatment (days)	21 (14–44)	7 (1–14)	.015

Data reported as median and interquartile range (IQR) or number and percentage.

Bold p-values indicate statistical significance.

^aA total of 206 patients were included in this analysis because 18 patients were excluded (15 were referred and 3 against advice).

Table 3. Analysis for factors independently associated with 30-day mortality.

Factors	Crude OR (95% CI)	p-Value	Adjusted OR^a (95% CI)	p-Value
Pneumonia	28.768 (7.86–105.28)	<.001	24.96 (5.95–104.75)	<.001
Bacteraemia	8.733 (1.15–66.47)	.036	3.66 (0.43–30.92)	.234
CKD	3.235 (1.13–9.25)	.028	2.79 (0.79–9.85)	.111
Age	1.035 (1.00–1.07)	.030	1.030 (0.99–1.07)	.100
SSTIs	0.3 (0.09–1.05)	.059	0.706 (0.18–2.80)	.621

Bold p-values indicate statistical significance.

^aAnalysis adjusted for all factors listed in the table.

OR: odds ratio; CI: confidence interval; CKD: chronic kidney disease; SSTIs: skin and soft tissue infections.

Data availability statement

The data that support the findings of this study are available from the corresponding upon reasonable request.