Table 3 Contingency tables linking some resistance phenotypes (to ATM, CTX and CAZ) to blaCTX-M PCR results (for blaCTX-M-1 and blaCTX-M-15).

From: Novel blaCTX-M variants and genotype-phenotype correlations among clinical isolates of extended spectrum beta lactamase-producing Escherichia coli

blaCTX-M PCR

Both negative

Either positive

Both positive

Total

ATM resistance

N (%row)

Either positive

N (%row)

R

3 (2.91%)

41 (39.8%)

59 (57.3%)

103 (100%)

I

4 (19.0%)

15 (71.4%)

2 (9.52%)

21 (100%)

S

25 (33.8%)

46 (62.2%)

3 (4.05%)

74 (100%)

Total

32 (16.2%)

102 (51.5%)

64 (32.3%)

198 (100%)

bla CTX-M PCR

Both negative

Either positive

Both positive

Total

CTX resistance

N (%row)

N (%row)

N (%row)

R

7 (4.93%)

74 (52.1%)

61 (43.0%)

142 (100%)

I

7 (30.4%)

13 (56.5%)

3 (13.0%)

23 (100%)

S

18 (54.5%)

15 (45.5%)

0 (0%)

33 (100%)

Total

32 (16.2%)

102 (51.5%)

64 (32.3%)

198 (100%)

bla CTX-M PCR

Both negative

Either positive

Both positive

Total

CAZ resistance

N (%row)

N (%row)

N (%row)

R

8 (5.23%)

85 (55.6%)

60 (39.2%)

153 (100%)

I

1 (6.67%)

10 (66.7%)

4 (26.7%)

15 (100%)

S

23 (76.7%)

7 (23.3%)

0 (0%)

30 (100%)

Total

32 (16.2%)

102 (51.5%)

64 (32.3%)

198 (100%)

Chi-square for ATM resistance vs. PCR results = 73.02 with 4 df; p ≤ 0.0001

Chi-square for CTX resistance vs. PCR results = 62.70 with 4 df; p ≤ 0.0001

Chi-square for CAZ resistance vs. PCR results = 97.98 with 4 df; p ≤ 0.0001

  1. Phenotype-genotype associations are tested by Chi-square test for independence. % row = percentage of row total.