Table 2.

Characteristic of study quality and articles.

Article	Intervention	Country	Study design	LE	Jadad Scale	Case (n)
						Probiotic	Control
Anukam a 2006 (Anukam et al., 2006a)	Antibiotic + Placebo vs Antibiotic	Nigeria	RCT	1b	4	49	57
Anukam b 2006 (Anukam et al., 2006b)	Probiotic vs Antibiotic	Nigeria	RCT	1b	3	17	18
Bohbot 2017 (Bohbot et al., 2018)	Antibiotic + Probiotic vs Antibiotic + Placebo	France	RCT	1b	3	50	48
Cohen 2020 (Cohen et al., 2020)	Probiotics vs Placebo	USA	RCT	1b	4	152	76
Erikson 2005 (Eriksson et al., 2005)	Antibiotic + Probiotic vs Antibiotic + Placebo	Finland	RCT	1b	3	91	96
Happel 2020 (Happel et al., 2020)	Antibiotic + Probiotic vs Antibiotic + Placebo	South Africa	RCT	1b	5	12	18
Hummerling 2010 (Hemmerling et al., 2010)	Antibiotic + Probiotic vs Antibiotic + Placebo	USA	RCT	1b	5	6	18
Hummelen 2010 (Hummelen et al., 2010)	Antibiotic + Probiotic vs Antibiotic + Placebo	Holland	RCT	1b	4	23	28
Larson 2008 (Larsson et al., 2008)	Antibiotic + Probiotic vs Antibiotic + Placebo	Sweden	RCT	1b	4	37	39
Laue 2017 (Laue et al., 2018)	Antibiotic + Probiotic vs Antibiotic + Placebo	German	RCT	1b	5	18	18
Marcotte 2019 (Marcotte et al., 2019)	Antibiotic + Probiotic vs Antibiotic	Sweden	RCT	1b	4	12	14
Martinez 2009 (Martinez et al., 2009)	Antibiotic + Probiotic vs Antibiotic + Placebo	Brazil	RCT	1b	4	32	32
Mastromarino 2008 (Mastromarino et al., 2009)	Probiotics vs Placebo	Italy	RCT	1b	3	18	16
Russo 2019 (Russo et al., 2019)	Antibiotic + Probiotic vs Antibiotic + Placebo	Italy	RCT	1b	3	24	24
Sgibnev 2009 (Sgibnev & Kremleva, 2020)	Antibiotic + Probiotic vs Antibiotic + Placebo	Rusian	RCT	1b	5	44	42
Vujic 2013 (Vujic et al., 2013)	Probiotics vs placebo	Croatia	RCT	1b	4	394	149

LE: Level of Evidence Base, 1b: Level of Evidence Randomized control trial.