Meta-Analysis on Efficacy of Autochthonous Lactic Acid Bacteria Supernatant from Dairy Goods in Suppressing Staphylococcus aureus

This systematic review assessed the antimicrobial activity of lactic acid bacteria (LAB) supernatant against Staphylococcus aureus, a common contaminant in dairy products. A comprehensive search of the PubMed, Scopus, and Web of Science databases was conducted for articles published between 2000 and 2022 using key terms such as dairy, starter cultures, and biopreservation. After thorough screening, articles written in English or Portuguese and presenting original results on the in vitro inhibition of S. aureus by LAB of dairy origin were selected, resulting in twenty-five relevant studies providing 190 observations. Using the 'metafor' package in R 4.1.2, meta-analysis models and graphs were constructed. The primary outcome measured was the mean inhibition zone diameter (ID) in mm and its standard error (SE). Results from the initial meta-regression model, employing a pathogen concentration of 7 log CFU/mL and an incubation time of 24 hours, indicated that the highest inhibition values against S. aureus were obtained by Lacticaseibacillus (11.89 ± 0.573), followed by Lactobacillus (11.35 ± 1.096), Lactococcus (11.33 ± 9.578), and Enterococcus (11.01 ± 2.105). A second model considered the susceptibility test method as a moderator, revealing that studies applying the well diffusion susceptibility test yielded higher inhibition values compared to spot and disk diffusion tests. The best fitted regression model for S. aureus evaluated the effect of LAB genus, pathogen concentration, incubation time, and susceptibility method. Notably, a positive correlation (p<0.001) between time and inhibition values was observed, with longer incubation periods (e.g., 72 hours) resulting in higher inhibition values (>20 mm). Moreover, the association between pH and inhibition diameter showed a significant inverse correlation (p<0.001). In conclusion, LAB strains naturally occurring in dairy products present variable activity against S. aureus and could be exploited in developing biocontrol strategies for the dairy industry.