3.1 Study selection
As shown in Figure 1 , a total of 12,279 records were retrieved
from the electronic databases, of which 84.5% were provided by VHL,
Scopus, and PubMed. In total, 4,815 publications remained after
duplicates were removed and once the screening of titles and abstract
was completed, 340 publications were retrieved in full text for final
eligibility. A total of 157 publications that met the inclusion criteria
were included in the quantitative synthesis. Among the 183 full text
publications that were excluded, the main reasons were: assessed SNT
isolates previously obtained (56.8%), lacked the defined population
(21.3%), and not a full text or other type of study different than the
defined (10.9%). A list of the publications that were excluded and the
primary reason for exclusion are provided in Supplementary Table
2 and a full reference list with all the included publications is
presented in Supplementary Table 3 .