Article Figures & Data
Figures
- FIG. 1.
Genetic organization of disease-associated type III effector nle genes in non-O157 STEC. (A) Graphic representation of the O-Island PAIs containing the nle effector genes examined in the present study in O157:H7 STEC strain EDL933. The direction of transcription for each open reading frame is indicated by an arrowhead. The type III effector genes examined are color-coded to each O-Island. nleG9 is adjacent to OI-71 but separated by multiple transposase elements and was therefore not included as part of OI-71. The annotation of open reading frames within each O-Island was modified from Perna et al. (26). (B) Pairwise association of nle genes from O-Islands 122, 57, 36, and 71 in non-O157:H7 STEC strains linked to outbreaks. The data are P values (Fisher exact test) for the co-occurrence of each disease-associated nle gene within the linked O-Island. nle genes that did not associate with outbreaks or HUS by MRA (nleB2 and nleD) were not included in pairwise comparisons. *, not-significant co-occurrence in non-HUS-associated strains (data not shown).
- FIG. 2.
Type III effector-gene dosage correlates with STEC virulence. (A) Distribution of nle gene content in O157 strains (n = 15) and non-O157 STEC strains (n = 57) (see Table S1 in the supplemental material for strain details). All O157 strains examined (red) contain all of the nle genes presented in Table 1. Non-O157 strains linked to human disease (yellow, green, and blue) contain a variable repertoire of disease-associated nle genes. Seropathotype E STEC strains not associated with human disease (purple) contain fewer nle genes relative to strains that are associated with outbreaks and HUS (seropathotype B), HUS only (seropathotype C), and diarrhea (seropathotype D). The data shown are the percentage of strains positive for the number of nle genes within each seropathotype. (B) Prevalence of nle genes in O157 and non-O157 STEC strains. Epidemic non-O157 strains have a significantly higher nle gene content compared to strains not linked to epidemics. Similarly, HUS-associated non-O157 strains have a significantly higher nle gene content compared to non-HUS-associated strains. O157 STEC contains all disease-associated nle genes identified. The data are means with standard errors.
Tables
- TABLE 1.
Oligonucleotides used for gene content analysis in non-O157 STEC
Gene targeta Oligonucleotide sequence (5′-3′) Product size (bp) Annealing temp (°C) Primer Primer 2 nleA ATGAACATTCAACCGACCATAC GACTCTTGTTTCTTGGATTATATCAAA 1,296 55 nleB GGAAGTTTGTTTACAGAGACG AAAATGCCGCTTGATACC 297 55 nleB2 GTTAATACTAAGCAGCATCC CCATATCAAGATAGATACACC 475 52 nleC ACAGTCCAACTTCAACTTTTCC ATCGTACCCAGCCTTTCG 777 55 nleD GGTATTACATCAGTCATCAAGG TTGTGGAAAACATGGAGC 426 55 nleE GTATAACCAGAGGAGTAGC GATCTTACAACAAATGTCC 260 52 nleF ATGTTACCAACAAGTGGTTCTTC ATCCACATTGTAAAGATCCTTTGTT 567 55 nleG (Z6010) ATGTTATCGCCCTCTTCTATAAAT ACTTAATACTACACTAATAAGATCCA 902 55 nleG2-1 (Z6025) ACCAGAAACCTGACTTCG CAGCATCTTCATATACTACAGC 406 55 nleG2-3 (Z2149) GGATGGAACCATACCTGG CGCAATCAATTGCTAATGC 551 56 nleG5-2 (Z2151) TGGAGGCTTTACGTCATGTCG CCGGAACAAAGGGTTCACG 504 55 nleG6-2 (Z2150) CGGGTCAGTGGATGATATGAGC AAGTAGCATCTAGCGGTCGAGG 424 55 nleG9 (Z2560) GTTCGTGCCCGAATTGTAGC CACCAACCAAACGAGAAAATG 409 55 nleH1-2 (Z6021) AACGCCTTATATTTTACC AGCACAATTATCTCTTCC 589 52 nleH1-1 (Z0989) GTTACCACCTTAAGTATCC GTTTCTCATGAACACTCC 456 55 ent/espL2 GAATAACAATCACTCCTCACC TTACAGTGCCCGATTACG 233 55 ↵ a Designations in parentheses are alternate gene names used previously.
- TABLE 2.
Distribution of complete O-Islands in HUS strains
Complete O-Island Prevalence (%) within STEC group (no. of strains with O-Island/ total no. of strains) Odds ratio (95% CI)a P Non-HUS associated HUS associated O-Island 36 7 (2/28) 14 (4/29) 2.1 (0.3-12.4) NSb O-Island 57 7 (2/28) 41 (12/29) 9.2 (1.8-46.3) <0.01 O-Island 71 7 (2/28) 45 (13/29) 10.6 (2.1-53.1) <0.01 O-Island 122 32 (9/28) 66 (19/29) 4.0 (1.3-12.1) <0.05 - TABLE 3.
Distribution of complete O-Islands in outbreak strains
Complete O-Island Prevalence (%) within STEC group (no. of strains with O-Island/ total no. of strains) Odds ratio (95% CI)a P Non-outbreak associated Outbreak associated O-Island 36 7 (3/42) 20 (3/15) 3.3 (0.6-18.3) NSb O-Island 57 17 (7/42) 46 (7/15) 4.4 (1.2-16.0) <0.05 O-Island 71 11 (5/42) 67 (10/15) 14.8 (3.6-61.4) 0.0001 O-Island 122 33 (14/42) 93 (14/15) 28 (3.3-235.2) <0.0001 - TABLE 4.
Prevalence of nle genes in non-O157 STEC strains associated with HUS
Genea Prevalence (%) within STEC group (no. of strains with O-Island/total no. of strains) Odds ratio (95% CI)b P Non-HUS associated HUS associated nleA 32 (9/28) 69 (20/29) 4.7 (1.5-14.3) 0.0081 nleB 32 (9/28) 69 (20/29) 4.7 (1.5-14.3) 0.0081 nleB2 17 (5/28) 24 (7/29) 1.5 (0.4-5.3) NSc nleC 25 (7/28) 62 (18/29) 4.9 (1.6-15.3) 0.0074 nleD 7 (2/28) 14 (4/29) 2.1 (0.3-12.4) NS nleE 32 (9/28) 66 (19/29) 4.0 (1.3-12.1) 0.0173 nleF 32 (9/28) 62 (18/29) 3.5 (1.2-10.3) 0.0343 nleG (Z6010) 11 (3/28) 62 (18/29) 13.6 (3.3-56.1) <0.0001 nleG2-1 (Z6025) 18 (5/28) 62 (18/29) 7.5 (2.2-25.6) 0.0011 nleG2-3 (Z2149) 25 (7/28) 66 (19/29) 5.7 (1.8-18) 0.0033 nleG5-2 (Z2151) 7 (2/28) 41 (12/29) 9.1 (1.8-46) 0.0046 nleG6-2 (Z2150) 18 (5/28) 52 (15/29) 4.9 (1.5-16.5) 0.0119 nleG9 (Z2560) 7 (2/28) 45 (13/29) 10.6 (2.1-53) 0.002 nleH1-2 (Z6021) 32 (9/28) 62 (18/29) 3.5 (1.2-10.3) 0.0343 nleH1-1 (Z0989) 32 (9/28) 62 (18/29) 3.5 (1/2-10.3) 0.0343 ent/espL2 32 (9/28) 69 (20/29) 4.7 (1.5-14.3) 0.0081 - TABLE 5.
Prevalence of nle genes in non-O157 STEC strains associated with outbreaks
Genea Prevalence (%) within STEC group (no. of strains with O-Island/ total no. of strains) Odds ratio (95% CI)b P Non-outbreak associated Outbreak-associated nleA 33 (14/42) 100 (15/15) 61 (3.4-1,093) <0.0001 nleB 33 (14/42) 100 (15/15) 61 (3.4-1,093) <0.0001 nleB2 14 (6/42) 40 (6/15) 4 (1-15.4) NSc nleC 29 (12/42) 87 (13/15) 16 (3.2-83) 0.0001 nleD 7 (3/42) 20 (3/15) 3.3 (0.6-18.3) NS nleE 33 (14/42) 93 (14/15) 28 (3.3-235.2) <0.0001 nleF 33 (14/42) 87 (13/15) 13 (2.6-65.8) 0.0006 nleG (Z6010) 19 (8/42) 87 (13/15) 28 (5.2-147.7) <0.0001 nleG2-1 (Z6025) 24 (10/42) 87 (13/15) 21 (4-108.3) <0.0001 nleG2-3 (Z2149) 29 (12/42) 93 (14/15) 35 (4.1-296.6) <0.0001 nleG5-2 (Z2151) 17 (7/42) 46 (7/15) 4.4 (1.2-16) 0.0344 nleG6-2 (Z2150) 24 (10/42) 67 (10/15) 6.4 (1.8-23.2) 0.0046 nleG9 (Z2560) 11 (5/42) 67 (10/15) 14.8 (3.6-61.4) 0.0001 nleH1-2 (Z6021) 33 (14/42) 87 (13/15) 13 (2.6-65.8) 0.0006 nleH1-1 (Z0989) 31 (13/42) 93 (14/15) 31 (3.7-263.4) <0.0001 ent/espL2 33 (14/42) 100 (15/15) 60.9 (3.4-1,093) <0.0001
Supplemental material
Files in this Data Supplement:
- Supplemental file 1
-
Strains used in this study (Table S1).
Zipped MS Excel file 245K.
- Supplemental file 1
-
Strains used in this study (Table S1).
