BackgroundUpdated prevalence and outcome data for nonobese NAFLD for the multi‐ethnic US population is limited.ObjectivesWe aimed to investigate the prevalence, clinical characteristics and mortality of obese and nonobese individuals with NAFLD in the United Sates.MethodsA retrospective study was conducted using the 1999–2016 NHANES databases. We determined hazard ratio stratified by obesity status in NAFLD individuals using Cox regression and log‐rank test.ResultsOverall NAFLD prevalence was 32.3%: 22.7% were obese and 9.6% were nonobese, with increasing trend over time for obese NAFLD, but not nonobese NAFLD. Amongst those with NAFLD, 29.7% (95% CI: 27.8%‐31.7%) were nonobese, of which 13.6% had lean NAFLD. Nonobese NAFLD was more common in older (40.9% if ≥ 65 vs. 24.2% if < 65 years), male (34.0% vs. 24.2%) and foreign‐born Asian people (39.8% vs. 11.4%) and uncommon in black (11.5% vs 30–35% in other ethnicities, P < 0.001). Metabolic comorbidities were common in nonobese NAFLD individuals who also had more advanced fibrosis. Nonobese NAFLD individuals had higher 15‐year cumulative all‐cause mortality (51.7%) than obese NAFLD (27.2%) and non‐NAFLD (20.7%) (P < 0.001). However, DM and fibrosis, but neither obese nor nonobese NAFLD compared to non‐NAFLD was independently associated with higher mortality.ConclusionNonobese NAFLD makes up about one‐third of the NAFLD in the United States (even higher in older, male and foreign‐born individuals) and carries higher mortality than obese NAFLD. Screening for NAFLD should be considered in high‐risk groups even in the absence of obesity.

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We found that the previously reported SS-B drug-supersusceptible mutant of Salmonella typhimurium (S. Sukupolvi, M. Vaara, I. M. Helander, P. Viljanen, and P. H. Mäkelä, J. Bacteriol. 159:704–712, 1984) had a mutation in the acrAB operon. Comparison of this mutant with its parent strain and with an AcrAB-overproducing strain showed that the activity of the AcrAB efflux pump often produced significant resistance to β-lactam antibiotics in the complete absence of β-lactamase. The effect of AcrAB activity on resistance was more pronounced with agents containing more lipophilic side chains, suggesting that such compounds were better substrates for this pump. This correlation is consistent with the hypothesis that only those molecules that become at least partially partitioned into the lipid bilayer of the cytoplasmic membrane are captured by the AcrAB pump. According to this mechanism, the pump successfully excretes even those β-lactams that fail to traverse the cytoplasmic membrane, because these compounds are likely to become partitioned into the outer leaflet of the bilayer. Even the compounds with lipophilic side chains were shown to penetrate across the outer membrane relatively rapidly, if the pump was inactivated genetically or physiologically. The exclusion of such compounds, exemplified by nafcillin, from cells of the wild-type S. typhimuriumwas previously interpreted as the result of poor diffusion across the outer membrane (H. Nikaido, Biochim. Biophys. Acta 433:118–132, 1976), but it is now recognized as the consequence of efficient pumping out of entering antibiotics by the active efflux process.