Ramadass Balamurugan

Real-time polymerase chain reaction quantification of specific butyrate-producing bacteria, Desulfovibrio and Enterococcus faecalis in the feces of patients with colorectal cancer

Background and Aim:  Bacterial metabolites produced in the bowel are potentially related to the genesis of colorectal cancer. Butyrate is protective against cancer, whereas hydrogen sulfide and oxygen free radicals can be toxic to the epithelium. The present study was designed to quantitate Eubacterium rectale, Faecalibacterium prausnitzii (both butyrate‐producing bacteria), Desulfovibrio (sulfate‐reducing bacteria), and Enterococcus faecalis (that produces extracellular superoxide) in the feces of patients with colorectal cancer.

Quantitative differences in intestinal Faecalibacterium prausnitzii in obese Indian children.

Gut bacteria contribute to energy conservation in man through their ability to ferment unabsorbed carbohydrate. The present study examined the composition of predominant faecal microbiota in obese and non-obese children. The participants (n 28) aged 11-14 years provided fresh faecal samples and completed a dietary survey consisting of 24 h diet recall and a FFQ of commonly used foods taken over the previous 3 months. Faecal bacteria were quantitated by real-time PCR using primers targeted at 16S rDNA. Of the participants, fifteen (seven female) were obese, with median BMI-for-age at the 99th percentile (range 97 to>99) while thirteen participants (seven female) were normal weight, with median BMI-for age being at the 50th percentile (range 1-85). Consumption of energy, carbohydrates, fat and protein was not significantly different between the obese and non-obese participants. There was no significant difference between the two groups in faecal levels of Bacteroides-Prevotella, Bifidobacterium species, Lactobacillus acidophilus group or Eubacterium rectale. Levels of Faecalibacterium prausnitzii were significantly higher in obese children than in non-obese participants (P = 0.0253). We concluded that the finding of increased numbers of F. prausnitzii in the faeces of obese children in south India adds to the growing information on alterations in faecal microbiota in obesity.

Probiotic administration alters the gut flora and attenuates colitis in mice administered dextran sodium sulfate

Background:  Probiotics are used in the therapy of inflammatory bowel disease. This study aimed to determine whether prior administration of probiotic lactobacilli and bifidobacteria would prevent disease and change gut flora in an animal model of colitis.

Molecular Studies of Fecal Anaerobic Commensal Bacteria in Acute Diarrhea in Children

Background and Objective: The commensal bacterial flora of the colon may undergo changes during diarrhea, owing to colonization of the intestine by pathogens and to rapid intestinal transit. This study used molecular methods to determine changes in the composition of selected commensal anaerobic bacteria during and after acute diarrhea in children. Materials and Methods: Fecal samples were obtained from 46 children with acute diarrhea in a rural community during an episode of acute diarrhea, immediately after recovery from diarrhea, and 3 months after recovery. DNA was extracted and quantitative polymerase chain reaction using SYBR green and genus- and species-specific primers targeting 16S rDNA were undertaken to quantitate the following groups of bacteria: Bifidobacterium spp., Bifidobacterium longum group, Bacteroides-Prevotella group, Bacteroides fragilis, Lactobacillus acidophilus group, Faecalibacterium prauznitzii, and Eubacterium rectale, relative to amplification of universal bacterial domain 16S rDNA. Results: Bacteria belonging to the Bacteroides-Prevotella-Porphyromonas group, E rectale, L acidophilus, and F prauznitzii groups were low during acute diarrhea compared with their levels after recovery from diarrhea. The pattern was similar in rotavirus diarrhea and nonrotavirus diarrhea. Administration of amylase-resistant maize starch as adjuvant therapy was associated with lower levels of F prauznitzii at the time of recovery but did not lead to other changes in the floral pattern. Conclusions: Specific classes of fecal bacteria are lower during episodes of acute diarrhea in children than during periods of normal gastrointestinal health, suggesting specific alterations in the flora during diarrhea.

PCR Amplification of the IS6110 Insertion Element of Mycobacterium tuberculosis in Fecal Samples from Patients with Intestinal Tuberculosis

ABSTRACT PCR amplification of insertion element IS6110 of Mycobacterium tuberculosis in fecal samples was evaluated in the diagnosis of intestinal tuberculosis (ITB). The numbers of samples that tested positive by PCR with SalI digestion were 16/18 untreated-ITB samples, 0/8 treated-ITB samples, 12/14 smear-positive pulmonary tuberculosis samples, and 0/30 control samples. The sensitivity, specificity, positive predictive value, and negative predictive value of fecal PCR were 88.8%, 100%, 100%, and 93.7%, respectively.

Bacterial succession in the colon during childhood and adolescence: molecular studies in a southern Indian village

BACKGROUND The colonic bacterial flora, largely anaerobic, is believed to establish and stabilize in the first 2 y of life. OBJECTIVE This study was undertaken to determine whether the bacterial flora of the colon undergoes further changes (succession) during childhood and adolescence. DESIGN This cross-sectional study examined fecal samples from 130 healthy children and adolescents in the age group 2-17 y and from 30 healthy adults (median age: 42 y) residing in a single village in southern India. DNA was extracted and subjected to 16S rDNA-targeted real-time polymerase chain reaction to determine the relative predominance of Bifidobacterium genus, Bacteroides-Prevotella-Porphyromonas group, Lactobacillus acidophilus group, Eubacterium rectale, and Faecalibacterium prausnitzii. RESULTS Bifidobacterium species and Bacteroides-Prevotella group were dominant fecal bacteria overall. E. rectale and Lactobacillus species were considerably less abundant. Clear age-related differences emerged, with a steep decline in Bifidobacterium species in adults (P < 0.0001), a steep decline of Lactobacillus species >5 y of age (P < 0.0001), an increase in Bacteroides during late adolescence and in adults (P = 0.0040), an increase in E. rectale during childhood and adolescence followed by a steep decline in adults (P < 0.0001), and a late childhood peak of F. prausnitzii with decline in adolescents and adults (P < 0.0001). CONCLUSIONS Changes in the bacterial flora occur during childhood and adolescence characterized by reduction in Lactobacillus and Bifidobacterium species and an increase in Bacteroides, E rectale, and F. prausnitzii peaked during late childhood in this population.

Low levels of faecal lactobacilli in women with iron-deficiency anaemia in south India.

Fe deficiency in women contributes significantly to maternal and child morbidity in India. The intestinal bacterial flora may facilitate absorption of Fe from the caecum and proximal colon. The present study investigated the possibility that intestinal microbiota of anaemic young women may differ from that of women with normal Hb levels. The microbiota was quantified by real-time PCR in faeces of eight anaemic (Hb ≤ 100 g/l) and twenty-six normohaemic (Hb ≥ 120 g/l) women aged 18-25 years. Sequences of 16S ribosomal DNA (rDNA) specific to Bifidobacterium genus, Lactobacillus acidophilus group, Bacteroides-Prevotella-Porphyromonas group, Clostridium leptum group and Eubacterium rectale were amplified and expressed (as relative difference) relative to the universally conserved bacterial 16S rDNA sequences. Dietary intakes of energy, carbohydrate, fibre and Fe were ascertained by maintenance of a diet diary for a week. Faecal lactobacilli were significantly lower in anaemic women (median 6.6 × 10(-8), relative difference compared with total bacteria) than in the reference group (2.9 × 10(-6); P = 0.001, unpaired t test with logarithmic transformation). There was no difference between the two groups with respect to any of the other bacteria that were examined. Intakes of energy, carbohydrate, fibre, Fe and milk were similar in both the groups. Fe deficiency in young women in south India was associated with low levels of lactobacilli in the faeces. The relationship between lactobacilli and Fe deficiency needs to be explored further.

Development of the gut microbiota in southern Indian infants from birth to 6 months: a molecular analysis.

Acquisition of the gastrointestinal microbiota at birth may have long-term health impacts. We longitudinally characterised major microbial communities in the faeces of a cohort of infants using molecular methods. Faecal samples were prospectively obtained at several time points after birth from eighty-three infants. Real-time PCR using SYBR green and primers targeted at 16S rRNA gene sequences were used to quantify Bifidobacterium, Lactobacillus acidophilus group, Bacteroides–Prevotella group, Enterobacteriaceae, Enterococcus, Clostridium coccoides–Eubacterium rectale group, Clostridium leptum group and Staphylococcus. Microbial community abundance was expressed relative to amplification of sequences conserved universally for domain bacteria. Faecal copy number of 16S rRNA genes increased non-significantly from a mean of 4·1 × 109/g on day 1 to 1·1 × 1010/g on day 4. All microbial communities were detected from day 1 after birth. Enterobacteriaceae and lactobacilli predominated on day 1, while bifidobacteria and staphylocci increased on day 4. Bacteroides–Prevotella and C. coccoides–E. rectale increased by day 180. C. leptum was detected in half of the cohort at birth and in a slightly larger percentage by 6 months. Caesarean section was associated with delayed colonisation by several bacterial communities. Higher socio-economic status was associated with more abundant lactobacilli and Bacteroides–Prevotella at 90 and 180 d. Supplemental feeding was associated with a reduction in Enterobacteriaceae. Microbial colonisation of the gut was well established on the first day of birth, and relative abundance of microbial communities was influenced by mode of delivery, socio-economic status and supplemental feeding. These findings may have relevance to infant nutrition and growth.

Prevalence of Adult Celiac Disease in India: Regional Variations and Associations.

Objectives:Although celiac disease (CeD) affects 1% of people in the northern part of India, it is believed to be uncommon in the southern and northeastern parts because of significant differences in dietary pattern and ethnicity. We estimated the prevalence of CeD in these three populations. In a subset, we also investigated differences in the prevalence of HLA-DQ 2/8 allelotype and dietary grain consumption.Methods:A total of 23,331 healthy adults were sampled from three regions of India—northern (n=6207), northeastern (n=8149), and southern (n=8973)—and screened for CeD using IgA anti-tissue transglutaminase antibody. Positive tests were reconfirmed using a second ELISA. CeD was diagnosed if the second test was positive and these participants were further investigated. A subsample of participants was tested for HLA-DQ2/-DQ8 and underwent detailed dietary evaluation.Results:Age-adjusted prevalence of celiac autoantibodies was 1.23% in northern, 0.87% in northeastern, and 0.10% in southern India (P<0.0001). Prevalence of CeD and latent CeD, respectively, was 8.53/1,000 and 3.70/1,000 in northern, 4.66/1,000 and 3.92/1,000 in northeastern, and 0.11/1,000 and 1.22/1,000 in the southern part. The population prevalence of genes determining HLA-DQ2 and/or -DQ8 expression was 38.1% in northern, 31.4% in northeastern, and 36.4% in southern India. Mean daily wheat intake was highest in northern (455 g) compared with northeastern (37 g) or southern part (25 g), whereas daily rice intake showed an inverse pattern.Conclusions:CeD and latent CeD were most prevalent in northern India and were the least in southern India. The prevalence correlated with wheat intake and did not reflect differences in the genetic background.

Molecular detection of the ruminal bacterium, Butyrivibrio fibrisolvens , in feces from rural residents of southern India

Objective: This study was undertaken to determine whether Butyrivibrio fibrisolvens, a butyrate-producing bacterium present in the rumen of cattle, could be detected in the feces of healthy southern Indians. Subjects and methods: Feces were collected from 25 children and 25 adults from a village and from 25 children living in a town in southern India. Four cow dung samples were also collected from the village. DNA was extracted and real-time PCR was carried out using primers targeted at 16S rDNA sequences peculiar to B. fibrisolvens. Amplicons were subjected to temporal temperature gradient electrophoresis (TTGE) and DNA sequencing. Phylogenetic analysis was done. Results:B. fibrisolvens rDNA was detected in feces of 13 adults (52%) and 15 children (60%) from the village, but not in urban children. In TTGE, amplicons from children and from cattle migrated as a single band, with only one sample showing a second band. Sequencing revealed 12 novel sequences (accessed in GenBank, 8 from children, 4 from dung) closely similar to the ATCC strain of B. fibrisolvens. Conclusions:B. fibrisolvens, a microorganism found in cattle, colonizes the human gastrointestinal tract in rural southern India.