Microbiota metabolism of intestinal amino acids impacts host nutrient homeostasis and physiology.

The intestine and liver are thought to metabolize dietary nutrients and regulate host nutrient homeostasis. Here, we find that the gut microbiota also reshapes the host amino acid (aa) landscape via efficiently metabolizing intestinal aa. To identify the responsible microbes/genes, we developed a metabolomics-based assay to screen 104 commensals and identified candidates that efficiently utilize aa. Using genetics, we identified multiple responsible metabolic genes in phylogenetically diverse microbes. By colonizing germ-free mice with the wild-type strain and their isogenic mutant deficient in individual aa-metabolizing genes, we found that these genes regulate the availability of gut and circulatory aa. Notably, microbiota genes for branched-chain amino acids (BCAAs) and tryptophan metabolism indirectly affect host glucose homeostasis via peripheral serotonin. Collectively, at single-gene level, this work characterizes a microbiota-encoded metabolic activity that affects host nutrient homeostasis and provides a roadmap to interrogate microbiota-dependent activity to improve human health.

Ultrasound diagnosis of congenital Morgagni hernias: Ten years of experience at two Chinese centers.

BACKGROUND: Morgagni hernias are rare anomalies that are easily misdiagnosed or missed. AIM: To summarize the ultrasound (US) imaging characteristics of Morgagni hernias through a comparison of imaging and surgical results. METHODS: The records of children with Morgagni hernias who were hospitalized at two hospitals between January 2013 and November 2023 were retrospectively reviewed in terms of clinical findings, US features, and operative details. RESULTS: Between 2013 and 2023, we observed nine (five male and four female) children with Morgagni hernias. Upper abdominal scanning revealed a widening of the prehepatic space, with an abnormal channel extending from the xiphoid process to the right or left side of the thoracic cavity. The channel had intestinal duct and intestinal gas echoes. Hernia contents were found in the transverse colon (n = 6), the colon and small intestine (n = 2), and the colon and stomach (n = 1). Among the patients, seven had a right-sided lesion, two had a left-sided lesion, and all of them had hernial sacs. CONCLUSION: US imaging can accurately determine the location, extent, and content of Morgagni hernias. For suspected Morgagni hernias, we recommend performing sonographic screening first.

Efficacy and safety of compound glycyrrhizin in combination with conventional therapy in treatment of vitiligo: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Vitiligo is an acquired chronic depigmentary disorder affecting approximately 0.5% to 1% of individuals worldwide. The compound glycyrrhizin (CG), a complementary medicine, has been reported for treatment of vitiligo, but the evidence has not been systematically evaluated. We systematically assessed the efficacy and safety of CG in combination with conventional therapy for the treatment of vitiligo. METHODS: We searched Embase, Web of Science, PubMed, The Cochrane Library, Chinese BioMedical Literature Database (CBM), Wanfang Data, China National Knowledge Infrastructure (CNKI), and VIP information from inception to July 2022. Randomized controlled trials comparing CG combined with conventional therapy with conventional therapy alone for vitiligo were included in our analysis. The primary outcome was treatment response, which defined as >50% repigmentation rate of vitiligo after treatment. The secondary outcome was incidence of adverse events. Meta-analysis was performed using the Review Manager 5.4 software. Statistical heterogeneity was evaluated with chi-square and I2 statistics, dichotomous data were expressed as risk ratios (RR) with 95% confidence intervals using the Mantel-Haenszal method. RESULTS: Thirty-nine studies enrolling with 3994 participants were subjected to this review. The results of our meta-analysis indicated that addition of CG had superior effectiveness on repigmentation rate than phototherapy (RR = 1.28; P < .001), immunosuppressant (RR = 1.76; P < .001), traditional Chinese medicine (RR = 1.38; P < .001), combination of phototherapy and immunosuppressant (RR = 1.42; P < .001), and combination of phototherapy and traditional Chinese medicine (RR = 1.37; P < .001). In addition, CG did not increase the incidence of adverse events for vitiligo (RR = 0.79; P = .05). CONCLUSIONS: CG as a complementary medicine has a potential benefit in treatment of vitiligo. However, since the methodological flaws in the studies we included, more high-quality randomized controlled trials are warranted.

Role of lncRNAs in acute pancreatitis: pathogenesis, diagnosis, and therapy.

Acute pancreatitis (AP) is one of the most common acute abdominal diseases characterized by an injury and inflammatory disorder of the pancreas with complicated pathological mechanisms. Long non-coding RNAs (lncRNAs) have been shown to play an important role in various physiological and pathological processes in humans, and they have emerged as potential biomarkers of diagnosis and therapeutic targets in various diseases. Recently, accumulating evidence has shown significant alterations in the expression of lncRNAs, which are involved in the pathogenesis of AP, such as premature trypsinogen activation, impaired autophagy, inflammatory response, and acinar cell death. Moreover, lncRNAs can be the direct target of AP treatment and show potential as biomarkers for the diagnosis. Thus, in this review, we focus on the role of lncRNAs in the pathogenesis, diagnosis, and therapy of AP and emphasize the future directions to study lncRNAs in AP, providing new insight into understanding the cellular and molecular mechanisms of AP and seeking novel biomarkers for the diagnosis and therapeutic targets to improve clinical management in the future.

[Protective Effect of Mesenchymal Stem Cell Transplantation on Intestinal Injury in Septic Mice and Its Mechanism].

Objective: To explore the protective effect of placenta-derived mesenchymal stem cells (P-MSCs) transplantation on intestinal injury in septic mice and its mechanism. Methods: A total of 24 mice were randomly assigned to 3 groups, a sham operation group, a sepsis group that underwent cecal ligation and puncture (CLP) procedure, and a group that received CLP and P-MSCs treatment. Hereinafter, the three groups are referred to as the Sham group, the CLP group, and the CLP+P-MSCs group. For the mice in the Sham group, the abdomen was cut open and the cecum was exposed and then placed back in the abdomen. CLP was performed in the other two groups to establish the sepsis model. Mice in the Sham and the CLP groups received 0.1 mL of 0.9% NaCl injection in the tail vein 1 hour after operation, while mice in the CLP+P-MSCs group received 2×10 5 P-MSCs infusion 1 hour after operation. Intestinal and blood specimens were collected from the mice in each group 24 hours after P-MSCs transplantation. Hematoxylin and eosin (HE) staining of the intestinal tissue was performed for pathological evaluation. The serum concentrations of D-lactic acid, diamine oxidase (DAO), endotoxin, interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, IL-6, IL-10, and transforming growth factor (TGF)-ß were determined by enzyme linked immunosorbent assay (ELISA). The gene expression of the relevant inflammatory factors in the small intestinal tissue was determined by real-time fluorescence polymerase chain reaction. The expression of zonula occludens protein-1 (ZO-1) and occludin protein in the intestine was determined by Western blot, the infiltration of intestinal macrophages was determined by immunohistochemical method, and the polarization of macrophages was determined by immunofluorescence. Results: The exogenous transplantation of P-MSCs could form colonies in the injured intestines of septic mice. Compared with those of the CLP group, the intestinal injury of the CLP+P-MSCs group was significantly alleviated, the serum concentrations of D-lactic acid, DAO, endotoxin, IL-1ß, IL-6, and TNF-α were significantly decreased ( P<0.05), while the serum concentrations of IL-10 and TGF-ß were significantly increased ( P<0.05), the expression levels of IL-1 ß, TNF-α and IL-6 genes in the intestinal tissue were significantly decreased ( P<0.05), while the expression levels of IL-10 and TGF-ß genes were significantly increased ( P<0.05), and the expression of ZO-1 and occludin proteins in the intestine was also significantly increased ( P<0.05). In addition, the distribution of macrophages in the intestinal tissue of the CLP+P-MSCs group decreased significantly and the macrophages showed a tendency for M2 polarization. Conclusion: Exogenous transplantation of P-MSCs can significantly reduce inflammatory injury and improve the intestinal barrier function in septic mice with intestinal injury. Reduction in the infiltration of macrophages and promotion of the polarization of macrophages from M1 to M2 may be the mechanisms underlying the reduction of inflammation.

Low-grade inflammation as mediator between diet and behavioral disinhibition: A UK Biobank study.

BACKGROUND: Dietary patterns have been associated with variations in behavior. However, evidence has been limited and mixed, and the underlying mechanism remains unclear. OBJECTIVE: Extend a previous study reporting significant associations between food patterns and behavioral disinhibition and explore whether low-grade inflammation is linked to behaviors and mediates the association between diet and behavioral disinhibition. DESIGN: Among participants of the UK Biobank (UKB) we extracted a single behavioral disinhibition principal component using the UKB touchscreen questionnaire, Mental Health Questionnaire (MHQ), and registered diagnoses. We identified four dietary patterns (prudent diet, elimination of wheat/dairy/eggs, meat-based diet, full-cream dairy consumption) by using the Food Frequency Questionnaire (FFQ). Immune biomarkers and an aggregated inflammation score (INFLA-score) were used to characterize low-grade inflammation. Associations between dietary patterns and immune biomarkers, between immune biomarkers and disinhibition were assessed, with adjustment for demographics, lifestyle factors, and somatic health conditions. Next, mediation analyses were run to examine whether the association between dietary patterns and disinhibition was partially explained by inflammatory levels. We also conducted subgroup analyses to explore whether associations and the mediation effect differed by sex, age, ethnicity/race, body-mass-index (BMI), and socioeconomic status (SES). RESULTS: The prudent diet was negatively, and the meat-based diet was positively associated with several pro-inflammatory biomarkers. Most immune biomarkers were positively associated with disinhibition (numbers of lymphocytes (ßstandardized = 0.082, p < 0.001), monocytes (ßstandardized = 0.043, p < 0.001), neutrophils (ßstandardized = 0.071, p < 0.001), platelets (ßstandardized = 0.022, p < 0.001), leukocytes (ßstandardized = 0.093, p < 0.001), C-reactive protein (ßstandardized = 0.051, p < 0.001), and for INFLA-score (ßstandardized = 0.074, p < 0.001). In the mediation model, the INFLA-score mediated the association between prudent diet and meat-based diet and disinhibition score, with a significant indirect effect of low-grade inflammation for the prudent diet-disinhibition association (ßstandardized = -0.007, p < 0.001) and for meat-disinhibition association (ßstandardized = 0.001, p < 0.001)). Although all effects were small, covariates and interaction term adjustments did not attenuate the effects, and neither did most subgroup-only analyses. CONCLUSIONS: The prudent diet was associated with a lower disinhibition score and this effect was partially mediated by the lower inflammation. Reversely, the meat-based diet was linked to more inflammation, which was associated with more disinhibition. Our findings suggest mediating effects of immune function in the relationship between diet and behavioral disinhibition. However further alternative designs such as interventional trials are needed to establish causal effects.

The gut microbiome as mediator between diet and its impact on immune function.

Dietary habits may affect inflammatory status in humans. Here we explore this interaction as well as the potential mediating role of the gut microbiome (GM), given that the GM is both involved in processing of dietary components and influences the immune system. A cross-sectional analysis of a sample of 482 healthy participants (207 males and 275 females) was performed. Dietary intake was assessed by a semiquantitative food questionnaire. Adipokines and soluble inflammatory mediators were assayed with multiple immunoassays and ELISA. Microbial DNA was extracted from frozen stool samples of 471 participants. Polychoric correlation analysis was used to establish dietary patterns, and joint multivariate associations between these dietary patterns and immune biomarkers were studied using regression analyses with adjustment for sex, age, BMI, smoking, education levels and physical exercise and other dietary patterns. Non-parametric entropy mediation was applied to investigate whether diet-immune relationships are mediated by abundance of microbial species. In this cohort, we identified three dietary patterns, characterized as "high-meat" (meat and sweetened drink), "prudent diet" (fish, fruit, legumes and vegetables) and "high alcohol" (higher alcohol consumption). Higher adherence to prudent diet was associated with a higher adiponectin level. The high alcohol pattern was associated with high concentrations of circulating concentrations of pro-inflammatory markers (CRP, IL-6, VEGF). Dialister invisus was found to mediate the relationship between a prudent dietary pattern and adiponectin, AAT, CRP, IL-6, and VEGF. In conclusion, a meat-based diet and a diet with high alcohol consumption were associated with high concentrations of biomarkers of chronic low-grade inflammation, and conversely, a prudent diet was associated with anti-inflammatory biomarkers. Diet-inflammation regulation may differ between sexes. Mediation analyses revealed that the association between prudent diet and immune function was partially mediated by the GM. The study adds to our understanding of the associations between diet, the immune system and the GM in a healthy population.

Genetic manipulation of gut microbes enables single-gene interrogation in a complex microbiome.

Hundreds of microbiota genes are associated with host biology/disease. Unraveling the causal contribution of a microbiota gene to host biology remains difficult because many are encoded by nonmodel gut commensals and not genetically targetable. A general approach to identify their gene transfer methodology and build their gene manipulation tools would enable mechanistic dissections of their impact on host physiology. We developed a pipeline that identifies the gene transfer methods for multiple nonmodel microbes spanning five phyla, and we demonstrated the utility of their genetic tools by modulating microbiome-derived short-chain fatty acids and bile acids in vitro and in the host. In a proof-of-principle study, by deleting a commensal gene for bile acid synthesis in a complex microbiome, we discovered an intriguing role of this gene in regulating colon inflammation. This technology will enable genetically engineering the nonmodel gut microbiome and facilitate mechanistic dissection of microbiota-host interactions.

Current pulse signature of native kanamycin aptamer and its implication for molecular interactions on a single protein nanopore sensing interface.

Due to the pore size limitation of single α-hemolysin (α-HL) nanopore sensing interface, ssDNA with secondary conformations can only pass through the nanopore after unzipping as linear ssDNA. For hairpin DNA, a tail with 15-50 bases was usually added to the stem terminal (5' or 3') to facilitate the capture rate and unzipping process, and the typical translocation signal behaves as a square wave with a short dip at the end of the pulse. In this work, the pulse signal of native kanamycin aptamer, a hairpin DNA without the added long tail, was investigated with the single nanopore sensing interface, and different current pulse pattern was observed. The pulse signal exhibited two precise current levels with significantly extended duration of the second, and both duration of the two levels correlate to the interaction of the aptamer to kanamycin. Moreover, the pulse signal not only reveals the selectivity of the aptamer to its target, but also sensitive to the loop sequence change of the aptamer. This work shows that a single nanopore sensing interface could be used as a unique alternative means for interaction investigation of hairpin DNA aptamer without labeling or adding the extra-long tail.

Cortical and Subcortical Brain Volumes Partially Mediate the Association between Dietary Composition and Behavioral Disinhibition: A UK Biobank Study.

Behavioral disinhibition is observed to be an important characteristic of many neurodevelopmental and psychiatric disorders. Recent studies have linked dietary quality to levels of behavioral inhibition. However, it is currently unclear whether brain factors might mediate this. The current study investigates whether cortical and subcortical brain volumes mediate part of the association between dietary composition and behavioral disinhibition. A total of 15,258 subjects from the UK Biobank project were included in the current study. Dietary composition and behavioral disinhibition were based on Principle Component Analyses of self-reported dietary composition). As a further data reduction step, cortical and subcortical volume segmentations were input into an Independent Component Analysis. The resulting four components were used as mediator variables in the main mediation analyses, where behavioral disinhibition served as the outcome variable and dietary components as predictors. Our results show: (1) significant associations between all dietary components and brain volume components; (2) brain volumes are associated with behavioral disinhibition; (3) the mediation models show that part of the variance in behavioral disinhibition explained by dietary components (for healthy diet, restricted diet, and high-fat dairy diet) is mediated through the frontal-temporal/parietal brain volume component. These results are in part confirming our hypotheses and offer a first insight into the underlying mechanisms linking dietary composition, frontal-parietal brain volume, and behavioral disinhibition in the general adult population.

Diet, Physical Activity, and Disinhibition in Middle-Aged and Older Adults: A UK Biobank Study.

Disinhibition is a prominent feature of multiple psychiatric disorders, and has been associated with poor long-term somatic outcomes. Modifiable lifestyle factors including diet and moderate-to-vigorous physical activity (MVPA) may be associated with disinhibition, but their contributions have not previously been quantified among middle-aged/older adults. Here, among N = 157,354 UK Biobank participants aged 40-69, we extracted a single disinhibition principal component and four dietary components (prudent diet, elimination of wheat/dairy/eggs, meat consumption, full-cream dairy consumption). In addition, latent profile analysis assigned participants to one of five empirical dietary groups: prudent-moderate, unhealthy, restricted, meat-avoiding, low-fat dairy. Disinhibition was regressed on the four dietary components, the dietary grouping variable, and self-reported MVPA. In men and women, disinhibition was negatively associated with prudent diet, and positively associated with wheat/dairy/eggs elimination. In men, disinhibition was also associated with consumption of meat and full-cream dairy products. Comparing groups, disinhibition was lower in the prudent-moderate diet (reference) group compared to all other groups. Absolute ßs ranged from 0.02-0.13, indicating very weak effects. Disinhibition was not associated with MVPA. In conclusion, disinhibition is associated with multiple features of diet among middle-aged/older adults. Our findings foster specific hypotheses (e.g., early malnutrition, elevated immune-response) to be tested in alternative study designs.

Rapid BMI Increases and Persistent Obesity in Small-for-Gestational-Age Infants.

Purpose: In order to compensate for the early intrauterine growth restriction, small-for-gestational age (SGA) infants have "catch-up growth" after birth. Increased caloric intake has been suggested for SGA infants conventionally. It is important to determine if the early growth rate of body mass index (BMI) is associated with risk of persistent obesity later in life. In this longitudinal cohort study, we assessed the BMI of a large cohort of children who were SGA at birth to determine their risk of persistent obesity at school age (6-7 years) due to excessive weight gain in the first 3 years of life. Methods: We collected the height and weight data of 23,871 SGA babies. A polynomial function was used to fit the BMI-for-age z-score (BAZ) values of 0-6 years old SGA children and interpolate their growth trajectory. In addition, we screened out 6,959 children from 23,871 children to further evaluate the dynamic changes of early childhood BMI. We divided the school-age children into groups as non-obese (BAZ < 2) and obese (BAZ > 2), and determined the association between changes in BMI and school-age obesity. Results: From the perspective of BMI distribution, the interpolated growth trajectory indicated that SGA children reaching overweight status or developing obesity by 3 years of age, continued to have obesity until school age (R2, 0.65; R2, 0.21). The retrospective analysis showed that children who were overweight and had obesity during school age had a high BMI from early age. By analyzing the changes in early BMI, we found that the fastest growth of SGA children occurred in the early infancy before 6 months and they continued to grow rapidly for a period of time. Interestingly, former SGA children who maintained a near overweight (1 < BAZ < 2) status before the age of 2 maintained an appropriate growth rate and usually did not develop obesity. Conclusions: A rapid increase in BMI during early infancy in former SGA newborns leads to a persistent risk of obesity. The energy intake of SGA infants should appropriately meet the infants' growth needs and early BMI changes should be closely monitored for an optimal integrated management.

Exploring the interaction of G-quadruplex and porphyrin derivative by single protein nanopore sensing interface.

Both human telomere and proto-oncogene c-MYC can form G-quadruplex (G4) with various conformations. Porphyrin derivative (TMPyP4) could stabilize G4, and thus is considered as a potential drug for anticancer therapeutics. In this paper, the translocation behaviors of three typical G4s (telomere basket, telomere hybrid-1 and c-MYC Pu22 parallel) and their interaction with TMPyP4 were investigated with a single protein nanopore sensing interface with the same main electrolyte of 0.5 M tetramethylammonium chloride. As observed by the statistics of the dwell time of the current pulses, in the presence of K+, the parallel G4 is more stable than the hybrid-1 G4, while the basket G4 in the presence of Na+ exhibited shortest duration. The dwell time of all of the G4s increased as the result of interaction with TMPyP4, indicating an obvious stabilizing effect. This study demonstrated that the single nanopore sensing interface not only reveal the stability of various G4 conformations at a single-molecule level, but also provide the interaction information of a ligand, which could be useful in the drug design.

Insights into infancy weight gain patterns for term small-for-gestational-age babies.

BACKGROUND: Too fast or slow weight gain in infancy is bad for health in later life. In this study, we aim to investigate the optimal weight gain pattern during the first 2 y of life for term small-for-gestational-age (SGA) infants. METHOD: We employed data from a longitudinal, community-based cohort study on the growth and development of SGAs collected between 2004 and 2010 in Shanghai, China. Latent class growth analysis (LCGA) was applied to identify weight gain patterns among 3004 SGAs. BMI curves for each latent class from 1 mo to 5 y were produced through mixed-effects regression analysis. Multivariable regression was performed to examine the association between various classes and adverse outcomes (overweight/obesity/ malnutrition) during 2-5 y. RESULT: Five weight gain patterns aged 0-2 y of 3004 term SGAs were identified and labeled as follows--class 1: excessively rapid catch-up growth (10.7%); class 2: rapid catch-up growth (19.7%); class 3: appropriate catch-up growth (55.7%); class 4: slow catch-up growth (10.2%); class 5: almost no catch-up growth (3.7%). A decreasing age at adiposity rebound (AR) and an increasing BMI value were observed from class 5 to 1. Class 1 and 2 showed an early appearance of AR (< 4 y). SGAs in class 1 and 2 had a higher BMI in 2-5 y of life. After adjustment for potential confounding variables, class 1 and 2 were found to have an increased risk of being overweight/ obese. At the same time, we found the risk of malnutrition was especially prominent among SGAs in classes 4 and 5. CONCLUSION: Our results suggest that for term SGA infants, catch-up growth that crossing two centile levels, that is, from < 10th to the interval between 25th and 50th (ΔWAZ> 1.28) in the first several months, along with on track growth and maintenance at a median level by age 2 may be the optimal catch-up growth trajectory, minimizing risk of childhood adverse health outcomes.

Growth of infants and young children born small for gestational age: growth restriction accompanied by overweight.

Objectives To compare growth profiles of children born small for gestational age (SGA) with those born the appropriate size for gestational age (AGA), and examine expected growth patterns for SGA in early childhood. Methods A survey on 23,871 SGA children was conducted in Shanghai. Data were collected at 1, 2, 4, 6, 8, 10, 12, 18, 24, 36, 48, and 60 months of age (+30 days). A check-up included assessments of weight, height, and head circumference. Results At 5 years old, weight, height, and head circumference were lower in SGA children compared with AGA children. The proportions of overweight and obesity of SGA children at 4 to 18 months after birth were significantly higher than those in AGA children, with higher proportions in boys than in girls. There was no correlation between overweight at 5 years old and overweight before 2 years old in SGA children. Conclusions Children born SGA remain shorter and lighter, with a smaller head circumference at 5 years old compared with AGA children. At 4 to 18 months after birth, there is a high incidence of overweight and obesity in SGA children. Overweight and obesity in SGA boys are more serious than those in SGA girls.

Epidemiology of CTX-M-type extended-spectrum beta-lactamase (ESBL)-producing nosocomial -Escherichia coli infection in China.

BACKGROUND: Escherichia coli is one of the most common clinical pathogens causing nosocomial infection. The widespread cefotaxime-beta lactamases (CTX) has increased the multidrug resistance (MDR) of E. coli and has brought great trouble to the doctor treating the infection. METHODS: ESBL-positive E. coli isolates were collected from different hospitals in different areas and the minimal inhibitory concentration (MIC) was analyzed by the agar dilution method. The resistance gene types were detected using polymerase chain reaction (PCR) and the sequence types were determined by multilocus sequence typing (MLST). RESULTS: We found that the blaCTX-M-1 group and the blaCTX-M-9 group were the main CTX-M gene types, with many kinds of MLST gene types. Except for TEM with high isolate, SHV, OXA and VEB were relatively rare, while no PER and GES was detected. Most strains may have other resistance mechanisms, and the ESBL positive strains have high resistance not only to cephalosporins but also to other kinds of antibiotics. CONCLUSION: The study provides wide epidemiological data and enables more effective infection control and treatment plans.

Opposite effects of cefoperazone and ceftazidime on S­ribosylhomocysteine lyase/autoinducer-2 quorum sensing and biofilm formation by an Escherichia coli clinical isolate.

To investigate the effects of subminimum inhibitory concentrations of cephalosporins on bacterial biofilm formation, the biofilm production of 52 Escherichia (E.) coli strains was examined following treatment with cephalosporin compounds at 1/4 minimum inhibitory concentrations (MICs). Ceftazidime (CAZ) inhibited biofilm formation in seven isolates, while cefoperazone (CFP) enhanced biofilm formation in 18 isolates. Biofilm formation of E. coli E42 was inhibited by CAZ and induced by CFP. Therefore, using reverse transcription­polymerase chain reaction, the expression of the biofilm­modulating genes of this isolate was investigated. To monitor the production of the autoinducer of quorum sensing in E. coli, autoinducer­2 (AI­2) production was detected by measuring the bioluminescence response of Vibrio harveyi BB170. Antisense oligonucleotides (AS­ODNs) targeting S­ribosylhomocysteine lyase (luxS) inhibited the expression of the luxS gene in E. coli. CAZ at 1/4 MIC reduced luxS mRNA levels and the production of AI­2, whereas CFP at 1/4 MIC had the opposite effect. AS­ODNs targeting luxS significantly decreased the aforementioned inhibitory effects of CAZ and the induction effects of CFP on E. coli biofilm formation. Therefore, biofilm formation by the E. coli clinical isolate E42 was evoked by CFP but attenuated by CAZ at sub­MICs, via a luxS/AI­2­based quorum sensing system.

Potent in vitro synergism of fusidic acid (FA) and berberine chloride (BBR) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).

It was found in the present study that combined use of fusidic acid (FA) and berberine chloride (BBR) offered an in vitro synergistic action against 7 of the 30 clinical methicillin-resistant Staphylococcus aureus (MRSA) strains, with a fractional inhibitory concentration (FIC) index ranging from 0.5 to 0.19. This synergistic effect was most pronounced on MRSA 4806, an FA-resistant isolate, with a minimum inhibitory concentration (MIC) value of 1,024 µg/ml. The time-kill curve experiment showed that FA plus BBR yielded a 4.2 log10 c.f.u./ml reduction in the number of MRSA 4806 bacteria after 24-h incubation as compared with BBR alone. Viable count analysis showed that FA plus BBR produced a 3.0 log10 c.f.u./ml decrease in biofilm formation and a 1.5 log10 c.f.u./ml decrease in mature biofilm in viable cell density as compared with BBR alone. In addition, phase contrast micrographs confirmed that biofilm formation was significantly inhibited and mature biofilm was obviously destructed when FA was used in combination with BBR. These results provide evidence that combined use of FA and BBR may prove to be a promising clinical therapeutic strategy against MRSA.

Detection of carbapenemase-encoding genes among clinical isolates of Pseudomonas aeruginosa in a Chinese burn unit.

The carbapenemases have recently emerged as molecules implicated in one of the most feared bacterial resistance mechanisms because of their ability to hydrolyze virtually all lactamase agents and their highly mobile genes. This study aimed to investigate the prevalence of carbapenemase and antimicrobial susceptibilities of Pseudomonas aeruginosa isolated from burn patients in Chongqing, China. Antimicrobial susceptibility of 111 isolates was determined by the disc agar diffusion test and the agar dilution method. Random Amplification of Polymorphic DNA polymerase chain reaction analysis revealed 111 P. aeruginosa 42 genotypes. Carbapenemase genes were amplified by polymerase chain reaction and the sequence verified by blast. Ninety-three of 111 (83.8%) isolates were resistant to imipenem; all of them had developed multidrug resistance and exhibited higher resistant rates compared with the imipenem-susceptible Pseudomonas. Ciprofloxacin was the most effective antipseudomonal agent. Thirty-three of the isolates were identified to contain the metallo-ß-lactamase blaIMP-4 gene and belong to different Random Amplification of Polymorphic DNA polymerase chain reactiongenotypes. In conclusion, the high prevalence of multidrug resistance (94.6%) and the production of blaIMP-4 genes in P. aeruginosa isolates in burn patients highlight the necessity of considering these issues in burn hospitals.