Table 1 Summary of data used for analyses in the 26 articles

Adams et al. [30]

USA

39 HC (− GI)

7.7 ± 4.4; 2.5–18

58 (± GI)

6.9 ± 3.4; 2.5–18

ATEC

Fecal

Cultures, Vitek^® 2 microbial identification system

De Angelis et al. [31]

Italy

10 SIB (− GI)

4–10

20 (− GI)

4–10

DSM-IV, ADI-R, CARS, ADOS

Fecal

Cultures, bTEFAP of the 16S rDNA and 16S rRNA

Finegold et al. [32]

USA

8 HC (n/a)

n/a

13 (+ GI)

n/a

n/a

Fecal

Gastric and duodenal fluids

Cultures, 16S rRNA

Finegold et al. [33]

USA

7 SIB (± GI)

8 HC (± GI)

2–13

33 (± GI)

2–13

Expert evaluation

Fecal

bTEFAP of 16S rRNA gene at the DNA level

Finegold et al. [34]

USA

13 HC (− GI)

2–9

33 (± GI)

2–9

n/a

Fecal

Cultures, PCR for the main C. perfringens toxins, verified with DNA sequencing

Gondalia et al. [35]

Australia

None

n/a

28 (± GI)

4.8 ± 3.3; 2–14

CARS, expert evaluation

Fecal

Cultures

Gondalia et al. [36]

Australia

53 SIB (8% + GI)

2–12

51 (55% + GI)

2–12

CARS, expert evaluation

Fecal

bTEFAP Gray28F 5′TTTGATCNTGGCTCAG and Gray519r 5′ GTNTTACNGCGGCKGCTG, qPCR

Inoue et al. [37]

Japan

6 HC (− GI)

3–5

6 (− GI)

3–5

DSM-5, PARS, M-CHAT

Fecal

Blood

16S rRNA, DNA microarray analysis of PBMC, qPCR

Iovene et al. [38]

Italy

33 HC (− GI)

7.3 ± 3.1

47 (70% + GI)

6.0 ± 2.8

DSM-IV-TR, ADI-R, CARS, ADOS

Fecal

Cultures, Vitek^® 2 microbial identification system

Kang et al. [39]

USA

20 HC (− GI)

8.3 ± 4.4; 3–16

20 (+ GI)

6.7 ± 2.7; 3–16

ADI-R, ADOS, ATEC, PDD-BI

Fecal

16S rRNA, bTEFAP 104F (59-GGCGVACGGGTGAGTA A-39) and 530R (59-CCGCNGCNGCT GGCAC-39)

Kang et al. [40]

USA

20 HC (− GI)

Age-matched

18 (+ GI)

7–16

ADI-R, CARS, SRS, ABC, PGI-III, VABS

Fecal

16S rRNA

Kang et al. [41]

USA

21 HC (± GI)

8.4 ± 3.4, 4–17

23 (± GI)

10.1 ± 4.1; 4–17

ADI-R, ADOS, ATEC, PDD-BI

Fecal

16S rRNA, 104F (59-GGCGVACGGGTGAGTAA-39) and 530R (59-CCGCNGCNGCTGGCAC-39),

Kushak et al. [42]

USA

19 HC (+ GI)

16.1 ± 1.3

21 (+ GI)

14.4 ± 1.1

DSM-IV

Duodenal biopsy

16S rRNA, Gray28F 50TTTGATCNTGGCTCAG

and Gray519r 50 GTNTTACNGCGGCKGCTG

Liu et al. [43]

China

None

n/a

20 (n/a)

1–8

DSM-5, CARS, ABC, SRS

Fecal

16S rRNA, CD 38 and RORA mRNA, 338F 5′-ACTCCTACGGGAGGCAGCA-3′ and 806R 5′-GGACTACHVGGGTWTCTAAT-3′

Luna et al. [44]

USA

21 HC (71% + GI)

3–18, + GI

3–14, -GI

14 (+ GI)

4–13

SRS, ADOS

Blood biopsy from colon

V1V3 and V4 regions of the 16S ribosomal RNA

Parracho et al. [45]

UK

12 SIB (25% + GI)

10 HC (− GI)

6 ± 2.15, 2–10

6 ± 2.88, 3–12

58 (91% + GI)

7 ± 3.76; 3–16

n/a

Fecal

FISH

Parracho et al. [46]

UK

None

n/a

17 (± GI)

4–16

DBC-P

Fecal

FISH

Shaaban et al. [47]

Egypt

30 HC (− GI)

Age and gender-matched

30 (− GI)

7.1 ± 1.4; 5–9

DSM-5, ADOS, ADI-R, ATEC, expert evaluation

Fecal

qPCR

Son et al. [48]

USA

44 SIB (30% + GI)

10.0 ± 1.8

8–13

59 (42% + GI)

10.3 ± 1.8; 8–13

ADI-R, ADOS, CBCL

Fecal

qPCR, V1V2 and V1V3 regions of 16S rRNA

Song et al. [49]

USA

8 HC (n/a)

n/a

15 (n/a)

n/a

n/a

Fecal

TaqMan qPCR of 16srRNA

Strati et al. [50]

Italy

40 HC (27.5% + GI)

9.2 ± 7.9

40 (12.5% + GI)

11.1 ± 6.8

DSM-5, ADOS, ABC, CARS

Fecal

16S rRNA and ITS sequencing

Tomova et al. [51]

Slovakia

9 SIB (78% + GI)

10 HC (60% + GI)

5–17

2–11

10 (90% + GI)

2–9

ADI-R, CARS, expert evaluation

Fecal

qPCR

Wang et al. [52]

Australia

22 SIB (27% + GI)

9 HC (11% + GI)

12 ± 1 (4.6–18.4)

9.5 ± 1.3 (3.5–15.2)

23 ( 39% + GI)

10.3 ± 0.8; 3.1–17.3

CARS, DSM-IV

Fecal

qPCR

Wang et al. [53]

Australia

22 SIB (27% + GI)

9 HC (11% + GI)

3–19

23 ( 39% + GI)

3–19

CARS, DSM-IV

Fecal

qPCR

Williams et al. [54]

USA

7 HC (+ GI)

4.0 ± 1.1; 3.9–5.5

15 (+ GI)

4.5 ± 1.3; 3.5–5.9

DSM-IV-TR, ADI-R, shortened CPEA regression interview

Biopsy from ileum and cecum

16sRNA

Williams et al. [55]

USA

9 HC (+ GI)

n/a

23 (+ GI)

n/a

DSM-IV-TR symptoms, ADI-R, shortened CPEA regression interview

Biopsy from ileum and cecum

Sutterella-specific 16S rRNA, qPCR