The impact of antibiotics on the metabolic status of obese adults without bacterial infection: a systematic review and meta-analysis

Background The gut microbiota is involved in the pathophysiology of obesity. It is known that oral antibiotics manipulate the gut microbiota; however, the impact on host metabolism of obese adults without bacterial infection has not been systematically summarized. Methods We searched for randomized, placebo-controlled trials that investigated the effects of oral antibiotics on the metabolic status in obese adults via Medline, EMBASE, and the Cochrane Library. Primary outcomes were homeostasis model assessment of insulin resistance (HOMA-IR), body weight, and rate of diarrhea. Additional outcomes included fasting plasma glucose (FPG), plasma glucagon-like peptide-1 (GLP-1), waist circumference, fecal short-chain fatty acid (SCFA) levels, and all adverse events. We assessed the certainty of evidence based on Grading of Recommendations, Assessment, Development and Evaluations. Results Among 1,762 articles screened, four studies were eligible for quantitative analysis, two of which were applied to meta-analysis. Oral antibiotics had low influence on HOMA-IR [mean difference (MD) 0.09 (95% CI: -0.96 to 1.13)], body weight [MD 4.1 kg (95% CI: -23.77 to 31.97)], FPG [MD -0.12 mmol/L (95% CI: -0.47 to 0.23)], and GLP-1 [MD 0.20 pmol/L (95% CI: -2.36 to 2.76)] compared to placebo. Antibiotics treatment altered fecal acetate and butyrate levels, but resulted in little difference in propionate levels [MD -13.60 µmol/g (95% CI: -22.43 to -4.77), MD -7.60 µmol/g (-10.97 to -4.23), MD -1.10 µmol/g (95% CI: -4.18 to 1.98), respectively]. Several adverse events, such as sun sensitivity and gastrointestinal discomfort, were reported following antibiotics treatment, but no diarrhea. The certainty of evidence for most outcomes was very low to low, except for fecal SCFAs. Conclusions Our results indicate that oral antibiotics treatment is insufficient to ameliorate metabolic parameters in obese adults, suggesting that oral antibiotics treatment may not qualify as a therapeutic approach for obesity.