Table 2.

Sample collection and treatment methods included in the study.

Study	Sample	Storage conditions	DNA extraction	Sequencing	Region for sequence	Database	Multiple comparisons
Jose 2018	Feces	NM	QIAamp DNA kit Stool Mini Kit (Qiagen)	Illumina MiSeq	V1-V2	Greengenes	Yes
Zhu 2018	Feces	-80°C	QIAamp DNA Stool	Illumina HiSeq	Metagenome	Virulence Factors of Pathogenic Bacteria database	Yes
Zhao 2019	Feces	-80°C	NM	BGISEQ-500	Metagenome	NM	No

NM: not mentioned.