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Table 4 Effects of gamma irradiation on ESBL production by five ESBLs-producing bacterial strains

From: Natural outer membrane permeabilizers boost antibiotic action against irradiated resistant bacteria

Isolate No./ Species of microorganism Radiation Half of inhibition zone (mm) in absence AMC / adjacent to AMC disk (DDST)
Mean ± SD (SE)
Half of inhibition zone (mm) in absence TZP/adjacent to TZP disk (MDDT)
Mean ± SD (SE)
AMC CTX CAZ FEP ATM TZP CAZ FEP
2/ Escherichia coli Before 5.5 ± 0.5(0.3) 3 ± 0.5(0.3) /7 ± 0.5(0.3) 3 ± 0.3 (0.2)
/8 ± 0.6 (0.3)
3 ± 0.2 (0.1)
/3 ± 0.6 (0.3)
3 ± 0.8 (0.5)
/3 ± 0.1 (0.1)
7 ± 0.8 (0.5) 3 ± 0.2 (0.1)
/9 ± 0.2 (0.1)
3 ± 0.5(0.3)
/6 ± 0.5(0.3)
After 6 ± 0.5(0.3) 3 ± 0.2 (0.1)
/7 ± 0.2 (0.1)
3 ± 0.5(0.3)
/8 ± 0.7 (0.4)
5 ± 0.4 (0.2)
/5 ± 0.1 (0.1)
3 ± 0.5(0.3)
/3 ± 0.7 (0.4)
9 ± 0.2 (0.1) 3 ± 0.4 (0.2)
/9 ± 0.2 (0.1)
5 ± 0.3 (0.2)
/8 ± 0.2 (0.1)
% of change 8.3 0.0
/0.0
0.0
/0.0
40
/40
0.0
/0.0
22.2 0.0
/0.0
40
/25
(p-value) 0.288 1.000
/1.000
1.000
/1.000
<0.001**
/0.005*
1.000
/1.000
0.014* 1.000
/1.000
0.004*
/0.003*
4/ Acinetobacter baumannii Before 5 ± 0.4 (0.2) 3 ± 0.5(0.3)
/3 ± 0.4 (0.2)
3 ± 0.2 (0.1)
/3 ± 0.4 (0.2)
3.5 ± 0.5(0.3)
/10 ± 0.6 (0.3)
3 ± 0.3 (0.2)
/7 ± 0.7 (0.4)
7.5 ± 0.5(0.3) 3 ± 0.7 (0.4)
/10 ± 0.2 (0.1)
3.5 ± 0.4 (0.2)
/3.5 ± 0.5(0.3)
After 5 ± 0.6 (0.3) 5 ± 0.3 (0.2)
/6 ± 0.6 (0.3)
5 ± 0.4 (0.2)
/6 ± 0.2 (0.1)
4 ± 0.5(0.3)
/11 ± 0.8 (0.5)
3 ± 0.8 (0.5)
/7 ± 0.2 (0.1)
9.5 ± 0.5(0.3) 5 ± 0.5(0.3)
/13 ± 0.4 (0.2)
4 ± 0.2 (0.1)
/5.5 ± 0.3 (0.2)
% of change 0.0 40
/50
40
/50
12.5
/9.1
0.0
/0.0
21.1 40
/23.1
12.5
/36.4
(p-value) 1.000 0.004*/
0.002*
<0.001**
/ <0.001**
0.288
/0.158
1.000
/1.000
0.008* 0.016*
/ <0.001**
0.125
/0.004*
8/ Pseudomonas aeruginosa Before 3 ± 0.9 (0.5) 3 ± 0.2 (0.1)/3 ± 0.5(0.3) 4.5 ± 0.4 (0.2)
/10 ± 0.2 (0.1)
8 ± 0.4 (0.2)
/12 ± 0.2 (0.1)
6 ± 0.3 (0.2)
/6 ± 0.5(0.3)
8.5 ± 0.5(0.3) 4.5 ± 0.5(0.3)
/11 ± 0.2 (0.1)
8 ± 0.2 (0.1)
/12 ± 0.4 (0.2)
After 5 ± 0.3 (0.2) 5 ± 0.4 (0.2)/6 ± 0.2 (0.1) 6.5 ± 0.2 (0.1)/13 ± 0.5(0.3) 9 ± 0.2 (0.1)
/13.5 ± 0.5(0.3)
7 ± 0.4 (0.2)/8 ± 0.2 (0.1) 12 ± 0.3 (0.2) 6 ± 0.2 (0.1)
/13.5 ± 0.5(0.3)
9 ± 0.1 (0.1)
/14 ± 0.2 (0.1)
% of change 40 40
/50
30.8
/23.1
11.1
/11.1
14.3
/25
29.2 25
/18.5
11.1
/14.3
(p-value) 0.22* <0.001**
/ <0.001**
<0.001**
/ <0.001**
0.018*
/0.008*
0.026*
/0.003*
<0.001** 0.008*
/ <0.001**
<0.001**
/ <0.001**
9/ Pseudomonas aeruginosa Before 3 ± 0.3 (0.2) 3 ± 0.5(0.3)
/3 ± 0.2 (0.1)
3 ± 0.4 (0.2)
/9 ± 0.2 (0.1)
3 ± 0.2 (0.1)
/8 ± 0.3 (0.2)
8 ± 0.2 (0.1)
/8 ± 0.5(0.3)
5.5 ± 0.5(0.3) 3 ± 0.2 (0.1)
/8 ± 0.4 (0.2)
3 ± 0.2 (0.1)
/7 ± 0.1 (0.1)
After 4.5 ± 0.5(0.3) 4.5 ± 0.5(0.3)
/5 ± 0.2 (0.1)
5 ± 0.2 (0.1)
/11 ± 0.4 (0.2)
5 ± 0.5(0.3)
/11 ± 0.2 (0.1)
9 ± 0.2 (0.1)
/10 ± 0.3 (0.2)
6.5 ± 0.3 (0.2) 5 ± 0.1 (0.1)
/10 ± 0.2 (0.1)
5 ± 0.5(0.3)
/10 ± 0.1 (0.1)
% of change 33.3 33.3
/40
40
/18.2
40
/22.3
11.1
/20
15.4 40
/20
40
/30
(p-value) 0.011* 0.021*
/ <0.001**
<0.001**
/ <0.001**
0.003*
/ <0.001**
0.004*
/0.004*
0.041* <0.001**
/ <0.001**
0.003*
/ <0.001**
13/ Enterobacter cloacae Before 4 ± 0.1 (0.1) 3 ± 0.2 (0.1)
/3 ± 0.5(0.3)
7 ± 0.1 (0.1)
/11 ± 0.4 (0.2)
6 ± 0.2 (0.1)
/11 ± 0.4 (0.2)
6 ± 0.2 (0.1)
/6 ± 0.1 (0.1)
10 ± 0.2 (0.1) 7 ± 0.1 (0.1)
/12 ± 0.2 (0.1)
6 ± 0.1 (0.1)
/10 ± 0.2 (0.1)
After 4 ± 0.5(0.3) 4 ± 0.1 (0.1)
/4 ± 0.3 (0.2)
8.5 ± 0.4 (0.2)/13 ± 0.2 (0.1) 6.5 ± 0.1 (0.1)
/12 ± 0.1 (0.1)
6 ± 0.2 (0.1)
/7 ± 0.3 (0.2)
12 ± 0.3 (0.2) 8.5 ± 0.1 (0.1)
/14 ± 0.2 (0.1)
6.5 ± 0.2 (0.1)/10.5 ± 0.3 (0.2)
% of change 0.0 25
/25
17.6
/15.4
7.5
/8.3
0.0
/14.3
16.7 17.6
/14.3
7.5
/4.8
(p-value) 1.000 <0.001**
/ 0.041*
0.003*
/ <0.001**
0.018*
/0.014*
1.000
/0.005*
<0.001** <0.001**
/ <0.001**
0.018*
/0.074
  1. DDST Double disk synergy test, MDDT Modified double disk synergy test p-value significant <0.05
  2. AMC (20/10 μg) = Amoxicillin /clavulanic Acid CTX (30 μg) = Cefotaxime p-value non significant > 0.05
  3. CAZ (30 μg) = Ceftazidime FEP (30 μg) = Cefepime p-value highly significant <0.001**
  4. ATM (30 μg) = Aztreonam TZP (100/10 μg) = Piperacillin / tazobactam