Unraveling the ties between irritable bowel syndrome and intestinal microbiota

Table 1 Summary of molecular studies of intestinal microbiota in irritable bowel syndrome

Ref.	Ethnicity	IBS patients, n	Mean age (range), yr	Male gender, n	IBS subtype			Controls, n	Sample	Method	Changes in intestinal microbiota composition in IBS
					IBS-C	IBS-D	IBS-M
Malinen et al[83] 2005	Finland	27	46.5 (20-65)	7	9	12	6	22 (age, gender matching)	Feces	qPCR covering bacteria 300 bacterial species	IBS-D: ↓ lactobacillus spp.
											IBS-C: ↑ veillonella spp.
											Overall IBS: ↓ clostridium coccoides subgroup, Bifidobacterium catenulatum group
Mättö et al[46] 2005	Finland	26	46 (20-65)	7	9	12	5	25 (age, gender matching)	Feces	Culture, PCR-DGGE	Temporal instability in the bacterial population↑ coliform bacteria
											↑ aerob:anaerob ratio
Maukonen et al[84] 2006	Finland	24	45 (24–64)	5	6	7	3	16	Feces	PCR-DGGE, Transcript analysis with the aid of affinity capture for Clostridial groups	Temporal instability in the bacterial population
											IBS-C: ↓ clostridium coccoides-Eubacterium rectale group
Kassinen et al[43] 2007	Finland	24	47.3 (21–65)	5	8	10	6	23 (age, gender matching)	Feces	GC-profiling + high-throughput 16S rRNA gene sequencing of 3753 clones	Coverage of the clone libraries of
											IBS subtypes and control subjects differed
Kerckhoffs et al[85] 2009	The Netherlands	41	42 ± 2.12	12	11	11	16	26	Feces, Duodenal mucosa	FISH, qPCR	↓ bifidobacterium catenulatum
Krogius-Kurikka et al[86] 2009	Finland	10	46.5	4	0	10	0	22	Feces	G + C (%G + C) -based profiling and fractioning combined with 16S rRNA gene clone library sequencing of 3267 clones	↑ proteobacteria
											↑ firmicutes
											↓ actinobacteria
											↓ bacteroidetes
Lyra et al[87] 2009	Finland	20	IBS-D: 43.6 (26-60), IBS-C: 48.6 (24-64), IBS-M: 50.8 (31-62)	6	8	8	4	15	Feces	qPCR	IBS-D: ↑ ruminococcus torques, ↓ clostridium thermosuccinogenes
											IBS-C: ↑ ruminococcus bromii-like
											IBS-M: ↓ ruminococcus torques, ↑ clostridium thermosuccinogenes
Tana et al[88] 2010	Japan	26	21.7 ± 2.0	13	11	8	7	26 (age, gender matching)	Feces	Culture, qPCR	↑ veillonella spp.
											↑ lactobacillus spp.
Codling et al[89] 2010	Ireland	47	43.6 (24–66)	0	-	-	-	33	Feces, Colonic mucosa	PCR-DGGE	Significantly more variation in the gut microbiota of healthy volunteers than that of IBS patients
Ponnusamy et al[90] 2011	South Korea	11	47.5 (18-74)	6	-	--		8	Feces	DGGE + qPCR of 16S rRNA genes	↑ diversity of Bacteroidetes and Lactobacillus groups
Rinttilä et al[91] 2011	Finland	96	47 (20-73)	27	15	81		23	Feces	qPCR	17% of IBS samples (n = 15) tested positive for staphylococcus aureus
Rajilić-Stojanović et al[45] 2011	Finland	62	49 (22−66)	5	18	25	19	42	Feces	Phylogenetic 16S rRNA microarray and qPCR	2-fold ↑ firmicutes:Bacteroidetes ratio↓ bacteroidetes, ↑ dorea, ruminococcus, clostridium sppBifidobacterium faecalibacterium spp
Carroll et al[51] 2011	United States	16	35.6 (23–52)	5	0	16	0	21	Feces, Colonic biopsies	T-RFLP fingerprinting of 16S rRNA-PCR	↓ microbial biodiversity in D-IBS fecal samples
Parkes et al[52] 2012	United Kingdom	53	IBS-D: 36.2 (32.1–40.3), IBS-C: 32.4 (28.1–36.7)	28	26	27	0	26	Colonic mucosa	FISH, confocal microscopy	Expansion of mucosa-associated microbiota; mainly bacteroides and clostridia; association with IBS subgroups and symptoms
Jeffery et al[92] 2012	Sweden	37	37 ± 12	11	10	15	12	20	Feces	Pyrosequencing 16SrRNA	Clustering of IBS patients: normal-like vs abnormal microbiota composition (increase of firmicutes-associated taxa and a depletion of bacteroidetes-related taxa)

IBS: Irritable bowel syndrome; IBS-D: Diarrhea-predominant irritable bowel syndrome; IBS-C: Constipation-dominant irritable bowel syndrome; IBS-M: Alternating type or mixed irritable bowel syndrome; PCR-DGGE: PCR denaturing gradient gel electrophoresis; FISH: Fluorescent in situ hybridization; qPCR: Quantitative PCR; 16S rRNA: 16S ribosomal RNA.