Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Ground Beef Collected in Different Socioeconomic Strata Markets in Buenos Aires, Argentina

Table 2

Distribution, according to the different socioeconomic strata, of virulence markers and antimicrobial susceptibility patterns of Shiga toxin-producing Escherichia coli isolated from ground beef in Buenos Aires, Argentina.

Strata

Proportion of STEC

Genotype

Phenotype

stx1

stx1 and stx2

stx2

eae

saa

ehxA

Serogroup

Antimicrobial susceptibility*

EHEC-Hly**

n (%)

n  (%)

n (%)

n (%)

n (%)

n (%)

O157

Non-O157***

S

R

R and r

r

n (%)

n (%)

n (%)

n (%)

n (%)

n (%)

n (%)

High

13/77

0; (0)

2; (13.3)

11; (84.6)

1; (7.7)

4; (30.8)

7; (53.8)

1; (7.7)

12; (92.3)

4; (30.8)

2; (13.3)

3; (23.1)

4; (30.8)

7; (53.8)

Media

25/91

3; (12)

1; (0.64)

21; (84.0)

8; (32.0)

3; (12)

15; (60.0)

5; (20.0)

20; (80.0)

10; (40.0)

3; (12)

4; (16.0)

8; (32.0)

7; (28.0)

Low

19/84

0; (0)

2; (10.5)

17; (89.5)

6; (31.6)

7; (36.8)

13; (68.4)

5; (26.3)

14; (73.7)

9; (47.4)

0; (0)

4; (21)

6; (31.6)

11; (57.9)

Total

57/252

3; (5.3)

5; (8.8)

49; (86.0)

15; (26.3)

14; (24.6)

35; (61.4)

11; (19.3)

46; (80.7)

23; (40.3)

5; (8.8)

11; (19.3)

18; (31.6)

25; (43.9)

∗Susceptibility patterns: S: susceptible, R: resistant, r: intermediate or reduced susceptible strains.
**The alfa-hemolytic strain belonging to media strata is not included.
***Non-O157 include serogroups OR and ONT.