The Gut Microbiota and Irritable Bowel Syndrome: Friend or Foe?

Table 1

Summary of the studies on the alteration in gut microbiota in IBS subjects.

S. No.	IBS (𝑛)	Healthy (𝑛)	Diagnostic criteria	Method	Outcome	Reference
1	11	8	Rome II	PCR and DGGE	Diversity of total bacteria along with Lacto bacillus was higher in IBS patients than healthy control	Ponnusamy et al. [1]
2	24	23	Rome II	Nucleic acid fractionation according to GC content, cloning followed by sequencing and qPCR	Collinsella aerofaciens, Clostridium cocleatum, and Coprococcus eutactus confirmed significant difference from that of healthy subjects	Kassinen et al. [18]
3	10	10	Rome III	Culture and q PCR	Significantly decreased quantity of aerobic bacteria in IBS than healthy control and increased concentration of Lactobacillus species in D-IBS patients than healthy control	Carroll et al. [19]
4	37	20	Rome II	DGGE and q PCR	Significant increase in the amount of Pseudomonas aeruginosa in IBS patients	Kerckhoffs et al. [33]
5	16	16	Rome II	RT-PCR-DGGE, Transcript analysis with the aid of affinity capture (TRAC)	Significantly decreased amount Clostridium coccoides-E. rectale in IBS-C	Maukonen et al. [106]
6	41	26	Rome II	FISH Analysis	Significantly decreased quantity of Bifidobacterium catenulatum in faecal and duodenal samples of IBS patients than healthy control	Kerckhoffs et al. [107]
7	44	34	Rome II	Culture and PCR	Significantly increased quantity of Enteraggroegative Escherichia coli in IBS-D	Sobieszczańska et al. [108]
8	20	15	Rome II	q PCR	Decreased quantity of Clostridium thermosuccinogens in IBS-D patients and increased quantity of Ruminococcus torque in IBS-D patients than healthy control. Ruminococcus bromii was more abundant in IBS-C than healthy control	Lyra et al. [109]
9	12	22	Rome II	% G + C profiling and fractioned DNA sequencing followed by q PCR	Significantly increased quantity of Proteobacteria and Firmicutes and reduced quantity of Actinobacteria and Bacteroidetes in IBS-D patients than healthy control	Krogius-Kurikka et al. [110]
10	25	25	Rome II	Culture	Significantly reduced number of Bifidobacterium and increased number of Enterobacteriaceae in IBS patients than healthy control	Si et al. [111]
11	47	33	Rome II	DGGE of 16S rRNA	Significant difference in gut microbiota in IBS patients and healthy control along with more variation in the gut microbiota in control than IBS subjects	Codling et al. [112]
12	26	26	Rome II	Culture and q PCR	Significantly increased quantity of Lactobacillus and Veillonella in IBS patients than control	Tana et al. [113]
13	10	10	Rome III	PCR and Pyrosequencing	Significantly increased number of Bacteroidetes and Synergistetes and reduced number of Actinobacteria, Bacilli, Flavobacteria, and Epsilonproteobacteria in IBS than control	Ng et al. [114]
14	22	22	Rome III	Metagenomics of 16S rRNA gene followed by PhyloChip hybridization and Pyrosequencing	Significantly greater abundance of class γ-Proteobacteria in IBS children than healthy control and Haemophilus parainfluenzae was prominent	Saulnier et al. [35]
15	62	46	Rome II	q PCR and microarray	Significantly 2-fold increased ratio of Firmicutes to Bacteroidetes in IBS patients comparison with the healthy control	Rajilić–Stojanović et al. [34]

IBS: irritable bowel syndrome; IBS-D: diarrhea predominant IBS; IBS-C: constipation predominant IBS; PCR: polymerase chain reaction; DGGE: denaturation gradient gel electrophoresis; q PCR: real time PCR; FISH: fluorescent in situ hybridization; TRAC: transcript analysis with the aid of affinity capture.