NOD2 variants and antibody response to microbial antigens in Crohn's disease patients and their unaffected relatives

BACKGROUND & AIMS: The Cdcs1 locus of the C3Bir mouse confers severe colitis associated with a decrease in innate immune function and an increase in adaptive T-cell responses to commensal bacterial products. The aim of our study was to determine if defects in innate immunity are similarly associated with increased adaptive immune responses to microbial antigens in Crohn's disease patients. METHODS: Sera from 732 patients, 220 unaffected relatives, and 200 healthy controls were tested for antibodies to oligomannan, the Pseudomonas fluorescens-related protein, Escherichia coli outer membrane porin C, CBir1 flagellin, and DNA from the same subjects was tested for 3 Crohn's disease-associated variants of the NOD2 gene, and 5 toll-like receptor (TLR) 2, 2 TLR4, and 2 TLR9 variants. The magnitude of responses to microbial antigens was examined according to variant status. RESULTS: NOD2 variant carriage increased in frequency with increasing number of positive antibodies and increasing cumulative quantitative response as measured by quartile sum (P for trend, .0008 and .0003, respectively). Mean antibody and quartile sums were higher for patients carrying any NOD2 variant versus those carrying none (2.24 vs 1.92 and 10.60 vs 9.72; P = .0008 and P = 0.0003, respectively). The mean quartile sum was higher for unaffected relatives carrying any NOD2 variant versus those carrying none (10.67 vs 9.75, respectively; P = .02). No association was found between any TLR variant and the magnitude of response. CONCLUSIONS: Patients with Crohn's disease and unaffected relatives carrying variants of the NOD2 gene have increased adaptive immune responses to microbial antigens.     

Association of antibody responses to microbial antigens and complications of small bowel Crohn's disease

BACKGROUND & AIMS: Crohn's disease patients can be characterized by antibody responses against Crohn's disease-related bacterial sequence, Escherichia coli outer membrane porin C, Saccharomyces cerevisiae (oligomannan), and neutrophil nuclear antigens. Our aim was to determine whether expression of antibodies against Crohn's disease-related bacterial sequence and Escherichia coli outer membrane porin C is associated with distinct phenotypic manifestations. METHODS: Sera from 303 patients were tested for antibodies to the Crohn's disease-related bacterial sequence (I2), anti-Escherichia coli outer membrane porin C, anti-Saccharomyces cerevisiae, and perinuclear antineutrophil cytoplasmic antibodies and for 3 Crohn's disease-associated variants of the NOD2 gene (R702W, G908R, and 1007fs) and compared with clinical data. RESULTS: Patients expressing I2 were more likely to have fibrostenosing Crohn's disease (64.4% vs. 40.7%; P < 0.001) and to require small bowel surgery (62.2% vs. 37.4%; P < 0.001). Patients with anti-Escherichia coli outer membrane porin C were more likely to have internal perforating disease (50.0% vs. 30.7%; P = 0.001) and to require small bowel surgery (61.4% vs. 44.2%; P = 0.003). Anti-Crohn's disease-related bacterial sequence was independently associated with fibrostenosis (P = 0.027) and small bowel surgery (P = 0.01), whereas anti-Escherichia coli outer membrane porin C was independently associated with internal perforations (P < 0.006). Patients positive for I2, anti-Escherichia coli outer membrane porin C, and anti-Saccharomyces cerevisiae were the most likely to have undergone small bowel surgery (72.0%; odds ratio, 8.6; P < 0.001) compared with patients without reactivity (23.0%). When the presence and magnitude of antibody responses were considered, 90% of patients with small bowel disease who required surgery had high levels of I2, Escherichia coli outer membrane porin C, and oligomannan antibodies, compared with only 18.2% with low-titer responses (P < 0.001). CONCLUSIONS: I2 and anti-Escherichia coli outer membrane porin C are associated with Crohn's disease phenotypes, and patients with the highest level of serum reactivity toward an increasing number of microbiota have the greatest frequency of strictures, internal perforations, and small bowel surgery.     

Antibodies to CBir1 flagellin define a unique response that is associated independently with complicated Crohn's disease

BACKGROUND & AIMS: Antibody responses to certain microbial antigens define heterogeneous groups of Crohn's patients; multiple and high-level responses to these antigens are associated with aggressive clinical phenotypes. The flagellin, CBir1, identified by investigations in the C3H/HeJBir mouse model, has been identified as a dominant antigen capable of inducing colitis in mice and eliciting antibody responses in a subpopulation of patients with Crohn's disease (CD). The aim of this study was to evaluate serum response to CBir1 flagellin in CD patients and to compare this response to responses defined previously to oligomannan (anti-Saccharomyces cerevisiae antibody), I2, OmpC, and neutrophil nuclear autoantigens (pANCA), and to determine anti-CBir1-associated phenotypes. METHODS: A total of 484 sera from the Cedars Sinai Medical Center repository, previously typed for anti-Saccharomyces cerevisiae antibody, anti-I2, anti-OmpC, and pANCA were tested for anti-CBir1 by enzyme-linked immunosorbent assay, and results were assessed for clinical phenotype associations. RESULTS: The presence and level of immunoglobulin G anti-CBir1 were associated with CD independently. Anti-CBir1 was present in all antibody subgroups and expression increased in parallel with increases in the number of antibody responses. pANCA+ CD patients were more reactive to CBir1 than were pANCA+ ulcerative colitis patients. Anti-CBir1 expression is associated independently with small-bowel, internal-penetrating, and fibrostenosing disease features. CONCLUSIONS: Serum responses to CBir1 independently identify a unique subset of patients with complicated CD. This bacterial antigen was identified in a murine model and has a similar pattern of aberrant reactivity in a subset of CD patients.     

High prevalence of adherent-invasive Escherichia coli associated with ileal mucosa in Crohn's disease

BACKGROUND & AIMS: Adherent-invasive Escherichia coli (AIEC) pathovar has been identified in the intestinal mucosa of patients with Crohn's disease (CD). AIEC reference strain LF82 is able to adhere to intestinal epithelial cells, to invade epithelial cells via a mechanism involving actin polymerization and microtubules, and to survive and replicate within macrophages. This study was performed to assess the prevalence of AIEC associated with intestinal mucosa of patients with CD, ulcerative colitis (UC), and of controls. METHODS: A search for E. coli strains was performed with ileal specimens of 63 patients with CD and 16 controls without inflammatory bowel disease (IBD), and with colonic specimens of 27 patients with CD, 8 patients with UC, and 102 controls. The abilities of E. coli strains to invade epithelial cells and to survive and replicate within macrophages were assessed using the gentamicin protection assay. Bacterial uptake by epithelial cells was analyzed using cytoskeletal inhibitors. Bacterial adhesion was quantified with Caco-2 and Intestine-407 cells. The presence of known E. coli virulence genes was assessed by polymerase chain reaction and DNA hybridization. RESULTS: In ileal specimens, AIEC strains were found in 21.7% of CD chronic lesions vs. in 6.2% of controls. In neoterminal ileal specimens, AIEC strains were found in 36.4% of CD early lesions (P = 0.034 vs. controls) and 22.2% of healthy mucosa of CD patients. In colonic specimens, AIEC strains were found in 3.7% of CD patients, 0% of UC patients, and 1.9% of controls. CONCLUSIONS: AIEC strains are associated specifically with ileal mucosa in CD.     

Hemophilic siblings with chronic hepatitis C: Familial aggregation of spontaneous and treatment-related viral clearance

BACKGROUND & AIMS: Hemophilic siblings provide a unique population to explore the natural history of chronic hepatitis C. METHODS: From 3993 hemophilic patients with hepatitis C, 257 sibling pairs, of which both members had evidence of hepatitis C infection, were studied to evaluate the genetic contribution to spontaneous and treatment-induced clearance of hepatitis C infection and progression of liver disease. Familial aggregation was assessed by comparing observed probabilities of concordance for these disease characteristics within sibling pairs to those expected for randomly paired hemophilic subjects. Additional measures of familial aggregation, heritability, and sibling relative risk were also calculated. RESULTS: Among human immunodeficiency virus-negative subjects, concordance for spontaneous viral clearance was 2-fold higher in siblings compared with randomly paired subjects (8.8% vs 4.3%, respectively, P = .04). Similarly, the concordance rate for treatment-related viral clearance was over twice that among sibling pairs than among randomly paired hemophiliacs (31.3% vs 13.3%, respectively, P = ns). Heritability estimates for spontaneous and treatment-induced viral clearance were 0.24 +/- 0.14 (P = .04) and 0.43 +/- 0.42 (P = .10), respectively. The sibling relative risks for these respective characteristics were 1.6 and 1.7. Concordance for advanced liver disease was higher among siblings but did not reach statistical significance (4.0% vs 2.3%, respectively, P = ns). The heritability estimate was 0.29 +/- 0.13 (P = .02). CONCLUSIONS: Concordance rates and heritability estimates for spontaneous and treatment-related viral clearance indicate that genetic factors have a modest influence on the outcome of hepatitis C, although shared environmental factors cannot be excluded. Investigations to map candidate disease-susceptibility genes associated with these characteristics must be approached with caution.     

Genetic variants of the mannan-binding lectin are associated with immune reactivity to mannans in Crohn's disease

BACKGROUND & AIMS: Some patients with Crohn's disease (CD) develop antibodies against mannan, a component of the yeast Saccharomyces cerevisiae cell wall. Mannan-binding lectin (MBL), a component of the innate immune system, can bind to S. cerevisiae . MBL concentration depends on genetic polymorphisms. The aim of this study was to evaluate whether low MBL contributes to anti-S. cerevisiae antibody (ASCA) production. METHODS: ASCA and MBL concentrations in sera from patients with CD (n = 74), ulcerative colitis (UC) (n = 22), and healthy controls (n = 32) were measured by an enzyme-linked immunosorbent assay (ELISA). Genetic MBL variants were determined from 58 CD patients, 18 UC patients, and 47 controls by DNA sequencing. Lymphocytes were tested for proliferative response after stimulation with mannan. RESULTS: ASCA were found in 47% of the patients with CD and in 0% of the controls. More ASCA-positive patients (52%) had low serum MBL concentrations compared with ASCA-negative patients (4%) (P < 0.0001). T-cell proliferation in response to mannan stimulation was observed in ASCA-positive patients and could be inhibited by the addition of MBL. These patients had significantly lower MBL serum concentrations than patients whose lymphocytes did not proliferate on mannan stimulation (P < 0.0001). Homozygous or compound heterozygous MBL mutations in the exon 1 and promoter occurred in 12 patients with cellular or humoral immune reactivity to mannan as compared with only 1 nonreactive patient (P < 0.0001). CONCLUSIONS: A subgroup of CD patients is characterized by ASCA positivity, T-cell proliferation on mannan stimulation, and mutations in the MBL gene that result in MBL deficiency. Thus, we propose that enhanced mannan exposure stimulates specific immune responses in a subgroup of CD patients with genetically determined low MBL concentrations. This enhanced exposure contributes to the generation of ASCA.     

Candida albicans is an immunogen for anti-Saccharomyces cerevisiae antibody markers of Crohn's disease

BACKGROUND AND AIMS: Antibodies directed against oligomannose sequences alpha-1,3 Man (alpha-1,2 Man alpha-1,2 Man)(n) (n = 1 or 2), termed anti-Saccharomyces cerevisiae antibodies (ASCAs) are markers of Crohn's disease (CD). S. cerevisiae mannan, which expresses these haptens, is used to detect ASCA, but the exact immunogen for ASCA is unknown. Structural and genetic studies have shown that Candida albicans produces mannosyltransferase enzymes that can synthesize S cerevisiae oligomannose sequences depending on growth conditions. This study investigated whether C. albicans could act as an immunogen for ASCA. METHODS: Sequential sera were collected from patients with CD, systemic candidiasis, and rabbits infected with C. albicans. Antibodies were purified by using chemically synthesized (Sigma) ASCA major epitopes. These affinity-purified antibodies and lectins were then used to analyze the expression of ASCA epitopes on molecular extracts and cell walls of C. albicans and S cerevisiae grown in various conditions. RESULTS: In humans and rabbits, generation of ASCA was shown to be associated with the generation of anti-C. albicans antibodies resulting specifically from infection. By using affinity-purified antibodies, C. albicans was shown to express ASCA epitopes on mannoproteins similar to those of S. cerevisiae. By changing the growth conditions, C. albicans mannan was also able to mimic S. cerevisiae mannan in its ability to detect ASCA associated with CD. This overexpression of ASCA epitopes was achieved when C. albicans grew in human tissues. CONCLUSIONS: C. albicans is one of several immunogens for ASCA and may be at the origin of an aberrant immune response in CD.     

Familial expression of anti-Saccharomyces cerevisiae mannan antibodies in affected and unaffected relatives of patients with Crohn's disease

BACKGROUND: Crohn's disease is a familial disorder, and antiglycan antibodies to the cell wall mannan of Saccharomyces cerevisiae (ASCA) are highly correlated with Crohn's disease. AIMS: To determine whether there is a familial pattern for expression of serum levels of anti-mannan Ig, and whether this trait is expressed in clinically unaffected Crohn's disease family members. METHODS: 349 patients with Crohn's disease, 87 Crohn's disease affected relatives, 333 inflammatory bowel disease (IBD) free relatives, 58 spouses, and 190 healthy control patients were studied. Serum IgG and IgA binding activity to S cerevisiae cell wall mannan was quantitated by ELISA. RESULTS: A high percentage of patients with Crohn's disease (51.9%) and affected family members (56.3%) were seropositive for anti-mannan Ig, compared with the normal control population (3.7%). Seropositive and seronegative phenotypes of Crohn's disease probands were correlated among all affected relatives, and this association was stronger in affected first degree relatives. Statistical intraclass correlations of quantitative anti-mannan Ig levels revealed significantly less variation within, rather than between families. A significant familial aggregation was observed for affected relatives; this was even stronger for unaffected relatives. While a significant familial aggregation was observed among unaffected siblings pairs, there was no significant correlation among marital pairs. CONCLUSION: Results show that anti-mannan Ig in family members affected and unaffected with Crohn's disease is a familial trait for both affected and unaffected relatives. The lack of concordance in marital pairs indicates that familiality is due in part to a genetic factor or childhood environmental exposure.     

Risk factors for initial surgery in pediatric patients with Crohn's disease

BACKGROUND & AIMS: The cumulative incidence of surgery ranges from 40%-70% at 10 years from the time of diagnosis of Crohn's disease in adults. We retrospectively determined the cumulative incidence of and risk factors for surgery (intestinal resection) in pediatric patients with Crohn's disease. METHODS: Uniform data from 989 consecutive Crohn's disease patients (age 0-17 years at diagnosis), collected from 6 different pediatric centers between January 2000 and November 2003 and stored in the Pediatric IBD Consortium Registry, were analyzed. RESULTS: Median follow-up time was 2.8 years (range, 1 day to 16.7 years). One hundred twenty-eight patients underwent surgery. Kaplan-Meier survival estimates of the cumulative incidence of surgery were 17% at 5 years and 28% at 10 years from the diagnosis of inflammatory bowel disease. Univariate Cox proportional hazards models showed leukocytosis (2.85 [hazard ratio]; P = .02), hypoalbuminemia (3.41; P = .05), and anti-Saccharomyces cerevisiae antibody (ASCA) positivity (3.43; P = .05) were associated with increased risk for surgery. Multivariate Cox models showed female gender (1.49; P = .03), initial diagnosis of ulcerative colitis (3.63; P < .0001), poor growth at presentation (2.16; P = .007), and abscess (1.90; P = .009), fistula (2.30; P = .0005), or stricture (3.41; P < .0001) development were associated with increased risk for surgery. Age 3-5 years (0.26; P = .01) or 6-12 years (0.62; P = .01) at diagnosis, fever at presentation (0.50; P = .03), and treatment with infliximab (0.36; P = .0005) or 5-aminosalicylic acid (0.44; P < .0001) were associated with decreased risk for surgery. CONCLUSIONS: Risk stratification during the course of Crohn's disease in pediatric patients will help to guide therapy that may improve the natural history of disease and decrease the need for surgery.     

Cancerous patients and outbreak of Escherichia coli: an important issue in oncology

The widespread of the Escherichia coli outbreak in Europe becomes an important public concern at global level. The infection can be serious and might result in death. The retrospective literature review on this specific topic is performed. In this specific brief article, the author presented and discussed on the problem of Escherichia coli infection in the cancerous patients. This is an actual important issue in medical oncology for the scenario of Escherichia coli epidemic.     

Molecular code for protein insertion in the endoplasmic reticulum membrane is similar for N(in)-C(out) and N(out)-C(in) transmembrane helices

Transmembrane α-helices in integral membrane proteins can have two orientations in the membrane: N_in–C_out or N_out–C_in. Previous studies of model N_out–C_in transmembrane segment have led to a detailed, quantitative picture of the “molecular code” that relates amino acid sequence to membrane insertion efficiency in vivo [Hessa T, et al. (2007) Molecular code for transmembrane helix recognition by the Sec61 translocon. Nature 450:1026–1030], but whether the same code applies also to N_in–C_out transmembrane helices is unknown. Here, we show that the contributions of individual amino acids to the overall efficiency of membrane insertion are similar for the two kinds of helices and that the threshold hydrophobicity for membrane insertion can be up to ≈1 kcal/mol lower for N_in–C_out compared with N_out–C_in transmembrane helices, depending on the neighboring helices.     

Purification and application of C-terminally truncated hepatitis C virus E1 proteins expressed in Escherichia coli

AIM: To explore the possibility of expressing hepatitis C virus (HCV) envelope protein 1 (E1) in Escherichia coli (E. coli) and to test the purified recombinant E1 proteins for clinical and research applications. METHODS: C-terminally truncated E1 fragments were expressed in E. coli as hexa-histidine-tagged fusion proteins. The expression products were purified under denaturing conditions using immobilized-metal affinity chromatography. Purified E1 proteins were used to immunize rabbits. Rabbit anti-sera thus obtained were reacted with both E. coli- and mammalian cell-expressed E1 glycoproteins as detected by Western blot. RESULTS: Full-length E1 protein proved difficult to express in E. coli. C-terminally truncated E1 was successfully expressed in E. coli as hexa-histidine-tagged recombinant fusion protein and was purified under denaturing conditions on Ni(2+)-NTA agarose. Rabbit anti-sera raised against purified recombinant E1 specifically reacted with mammalian cell-expressed E1 glycoproteins in Western blot. Furthermore, E. coli-derived E1 protein was able to detect animal antibodies elicited by E1-based DNA immunization. CONCLUSION: These results demonstrate that the prokaryotically expressed E1 proteins share identical epitopes with eukaryotically expressed E1 glycoprotein. The E. coli-derived E1 proteins and corresponding antisera can become useful tools in anti-HCV vaccine research.     

Clinical significance of anti-Saccharomyces cerevisiae antibody (ASCA) in Korean patients with Crohn''s disease and its relationship to the disease clinical course

BACKGROUNDS/AIMS: The implications of anti-Saccharomyces cerevisiae antibody for the diagnosis and the clinical course of Crohn's disease have been reported in Western countries, but rarely in Korea with its very different environmental and genetic backgrounds. We aimed to evaluate whether anti-S. cerevisiae antibody expression is associated with diagnostic findings, stratified Vienna classification phenotypes, disease activity and clinical course in Korean patients with Crohn's disease. MATERIALS/METHODS: One hundred and fifteen patients with Crohn's disease, diagnosed and treated between 1990 and 2004 at Severance Hospital, Yonsei University and followed for at least 2 years, were included in this study. Anti-S. cerevisiae antibody was detected by an indirect immunofluorescence assay using EUROIMMUN kits. Information collected during treatment included demography, Vienna classification phenotype, clinical manifestation, laboratory tests, treatment modality and surgery rate. Disease activity was measured monthly using the Harvey-Bradshaw index. RESULTS: The anti-S. cerevisiae antibody prevalence was 38.3% in Crohn's disease patients. There was no difference in anti-S. cerevisiae antibody expression between genders. The mean age at diagnosis was younger for the anti-S. cerevisiae antibody positive group than the negative group (25.3 years versus 29.7 years, p<0.05). Clinical manifestations and laboratory tests at diagnosis did not differ between the groups. The anti-S. cerevisiae antibody positive group had increased fibrostenosis (B2) and penetration (B3) compared to negative group, as determined by the Vienna classification (75.0% versus 53.5%, p<0.05). Anti-S. cerevisiae antibody positive patients were admitted to the hospital more frequently than anti-S. cerevisiae antibody negative patients (p<0.05). The yearly cumulative Harvey-Bradshaw index score was higher in the anti-S. cerevisiae antibody positive group than in the negative group during the follow-up period (p<0.05). In addition, steroid (72.7% versus 52.1%, p<0.05) and immunosuppressive (45.5% versus 23.9%, p<0.05) treatments were more frequently given to the anti-S. cerevisiae antibody positive group. CONCLUSIONS: Our data demonstrate that anti-S. cerevisiae antibody positive Crohn's disease patients had a more severe clinical course and thus often required more aggressive medical treatment.     

Presence of adherent Escherichia coli strains in ileal mucosa of patients with Crohn's disease

Background & Aims: Infectious agents are suspected of being involved in the pathogenesis of Crohn's disease. This study was designed to look for the presence of virulent Escherichia coli strains associated with the ileal mucosa of patients with Crohn's disease. Methods:E. coli strains were recovered from resected chronic ileal lesions (n = 20), neoterminal ileum after surgery from patients with (n = 19) and without (n = 11) endoscopic recurrence, and controls (n = 13). Bacterial adhesion was determined in vitro using intestinal cell lines; other associated virulence factors were assessed by DNA hybridization and polymerase chain reaction experiments. Results: None of the strains harbored any of the virulence factor–encoding genes of E. coli involved in acute enteric diseases. However, mannose-resistant adhesion to differentiated Caco-2 cells was found for 84.6% and 78.9% of the E. coli strains isolated from chronic and early recurrent lesions, respectively, compared with 33% of controls (P < 0.02). In addition, 21.8% of the strains induced a cytolytic effect by synthesis of an α-hemolysin. Conclusions:E. coli strains isolated from the ileal mucosa of patients with Crohn's disease adhere to differentiated intestinal cells and may disrupt the intestinal barrier by synthesizing an α-hemolysin.GASTROENTEROLOGY 1998;115:1405-1413     

A single mutation in the first transmembrane domain of yeast COX2 enables its allotopic expression

During the course of evolution, a massive reduction of the mitochondrial genome content occurred that was associated with transfer of a large number of genes to the nucleus. To further characterize factors that control the mitochondrial gene transfer/retention process, we have investigated the barriers to transfer of yeast COX2, a mitochondrial gene coding for a subunit of cytochrome c oxidase complex. Nuclear-recoded Saccharomyces cerevisiae COX2 fused at the amino terminus to various alternative mitochondrial targeting sequences (MTS) fails to complement the growth defect of a yeast strain with an inactivated mitochondrial COX2 gene, even though it is expressed in cells. Through random mutagenesis of one such hybrid MTS-COX2, we identified a single mutation in the first Cox2 transmembrane domain (W56 → R) that (i) results in the cellular expression of a Cox2 variant with a molecular mass indicative of MTS cleavage, which (ii) supports growth of a cox2 mutant on a nonfermentable carbon source, and that (iii) partially restores cytochrome c oxidase-specific respiration by the mutant mitochondria. COX2^W56R can be allotopically expressed with an MTS derived from S. cerevisiae OXA1 or Neurospora crassa SU9, both coding for hydrophobic mitochondrial proteins, but not with an MTS derived from the hydrophilic protein Cox4. In contrast to some other previously transferred genes, allotopic COX2 expression is not enabled or enhanced by a 3′-UTR that localizes mRNA translation to the mitochondria, such as yeast ATP2^3′-UTR. Application of in vitro evolution strategies to other mitochondrial genes might ultimately lead to yeast entirely lacking the mitochondrial genome, but still possessing functional respiratory capacity.     

Cotrimoxazole-resistant Escherichia coli bacteremia in neutropenic patients at a regional oncology hospital

In a regional oncology hospital using cotrimoxazole (trimethoprim-sulphamethoxazole) prophylaxis during chemotherapy-induced neutropenia, a single strain of Escherichia coli (indole negative) caused 15 of 27 episodes of Gram-negative rod bacteremia in 1987, and four of 32 such episodes in 1988. This biotype had not been recovered in 1986. Investigations during this ‘outbreak’ of bacteremias revealed enteric colonization with this strain of E coli in 37% of patients on leukemia or bone marrow transplant wards and in several staff members in July 1987. In 1988, 11 of 32 Gram-negative rod bacteremias were secondary to other strains of indole positive E coli of several different biotypes and plasmid profiles. Indole negative strains all exhibited low level trimethoprim resistance, whereas indole positive strains which subsequently appeared exhibited high level trimethoprim resistance. Failure of cotrimoxazole prophylaxis was initially due to the clonal dissemination of a single strain of E coli within the institution, with the subsequent appearance of multiple E coli strains with probable differing genetic bases for their resistance.     

Lactobacillus reuteri and Escherichia coli in the human gut microbiota may predict weight gain associated with vancomycin treatment

Background:

Antibiotics, used for 60 years to promote weight gain in animals, have been linked to obesity in adults and in children when administered during early infancy. Lactobacillus reuteri has been linked to obesity and weight gain in children affected with Kwashiorkor using ready-to-use therapeutic food. In contrast, Escherichia coli has been linked with the absence of obesity. Both of these bacteria are resistant to vancomycin.

Objectives and methods:

We assessed vancomycin-associated weight and gut microbiota changes, and tested whether bacterial species previously linked with body mass index (BMI) predict weight gain at 1 year. All endocarditis patients treated with vancomycin or amoxicillin in our center were included from January 2008 to December 2010. Bacteroidetes, Firmicutes, Lactobacillus and Methanobrevibacter smithii were quantified using real-time PCR on samples obtained during the 4–6 weeks antibiotic regimen. L. reuteri, L. plantarum, L. rhamnosus, Bifidobacterium animalis and E. coli were quantified on stool samples obtained during the first week of antibiotics.

Results:

Of the193 patients included in the study, 102 were treated with vancomycin and 91 with amoxicillin. Vancomycin was associated with a 10% BMI increase (odds ratio (OR) 14.1; 95% confidence interval (CI; 1.03–194); P=0.047) and acquired obesity (4/41 versus 0/56, P=0.01). In patients treated with vancomycin, Firmicutes, Bacteroidetes and Lactobacillus increased, whereas M. smithii decreased (P<0.05). The absence of E. coli was an independent predictor of weight gain (OR=10.7; 95% CI (1.4–82.0); P=0.02). Strikingly, a patient with an 18% BMI increase showed a dramatic increase of L. reuteri but no increase of E. coli.

Conclusion:

The acquired obesity observed in patients treated with vancomycin may be related to a modulation of the gut microbiota rather than a direct antibiotic effect. L. reuteri, which is resistant to vancomycin and produces broad bacteriocins, may have an instrumental role in this effect.