Difference between kwashiorkor and marasmus: Comparative meta-analysis of pathogenic characteristics and implications for treatment

Kwashiorkor and marasmus are two clinical syndromes observed in severe acute malnutrition. In this review, we highlighted the differences between these two syndromes by reviewing the data comparing kwashiorkor and marasmus in literature, combined with recent microbiological findings and meta-analysis. Depletion of antioxidants, vitamins and minerals were more severe in kwashiorkor than marasmus. This was consistent with the severe and uncontrolled oxidative stress associated with the depletion of gut anaerobes and the relative proliferation of aerotolerant gut pathogens. This relative proliferation and invasion of gut microbes belonging to the aerotolerant Proteobacteria phylum and pathogens suggested a specific microbial process critical in the pathogenesis of kwashiorkor. Liver mitochondrial and peroxisomal dysfunction could be secondary to toxic microbial compounds produced in the gut such as ethanol, lipopolysaccharides and endotoxins produced by Proteobacteria, particularly Klebsiella pneumoniae, and aflatoxin produced by Aspergillus species. The gut-liver axis alteration is characterized by oedema and a fatty and enlarged liver and was associated with a dramatic depletion of methionine and glutathione, an excessive level of free circulating iron and frequent lethal bacteraemia by enteric pathogens. This was consistent with the fact that antibiotics improved survival only in children with kwashiorkor but not marasmus. The specific pathogenic characteristics of kwashiorkor identified in this review open new avenues to develop more targeted and effective treatments for both marasmus and/or kwashiorkor. Urgent correction of plasma glutathione depletion, alongside supply of specific essential amino acids, particularly methionine and cysteine, early detection of pathogens and an antibiotic more efficient than amoxicillin in supressing gut Proteobacteria including K. pneumoniae, and probiotics to restore the human gut anaerobic mature microbiota could save many more children with kwashiorkor. •Pathophysiological features are associated to a specific metabolic and microbial profile in kwashiorkor.•The depletion in antioxidants, minerals and vitamins is more severe in kwashiorkor than in marasmus.•Proliferation of aerotolerant microbes and Proteobacteria in the gut in kwashiorkor with toxic microbial metabolites.•Oedema and fatty liver in kwashiorkor associated with a depletion of methionine and glutathione, free iron and bacteraemia.