Table 3.
The distribution of different β-lactamase genes associated with their minimum inhibitory concentration (MIC) values of ceftazidime–avibactam and ceftolozane–tazobactam.
| Antimicrobial Agent | Ceftazidime–Avibactam | Ceftolozane–Tazobactam | Total Genes | ||||
|---|---|---|---|---|---|---|---|
| Susceptibility Result | Susceptible | Resistant | Extremely Resistant | Susceptible | Resistant | Extremely Resistant | |
| MIC 0.75–8 | MIC 12–192 | MIC ≥ 256 | MIC 0.75–8 | MIC 12–48 | MIC ≥ 256 | ||
| Gene | Frequency (%) | Frequency (%) | |||||
| Class A β-lactamase | |||||||
| VEB-9 | 3 (15.8) | 10 (52.6) | 6 (31.6) | 0 | 1 (5.6) | 18 (94.7) | 19 |
| TEM-116 | 6 (100) | 0 | 0 | 5 (83.3) | 1 (16.7) | 0 | 6 |
| CTX-M-15 | 2 (66.7) | 0 | 1 (33.3) | 2 (66.7) | 0 | 1 (33.3) | 3 |
| SHV-11 | 1 (33.33) | 1 (33.33) | 1 (33.33) | 1 (33.33) | 1 (33.33) | 1 (33.33) | 3 |
| TEM-1 | 0 | 0 | 1 (100) | 0 | 0 | 1 (100) | 1 |
| TEM-126 | 0 | 0 | 1 (100) | 0 | 0 | 1 (100) | 1 |
| CARB-3a | 1 (100) | 0 | 0 | 1 (100) | 0 | 0 | 1 |
| p-value † | 0.002 | <0.001 | |||||
| Class B β-lactamase | |||||||
| VIM-2 | 0 | 14 (87.5) | 2 (12.5) | 0 | 3 (18.7) | 13 (81.3) | 16 |
| IMP-1 | 0 | 0 | 3 (100) | 0 | 0 | 3 (100) | 3 |
| VIM-5 | 0 | 0 | 2 (100) | 0 | 0 | 2 (100) | 2 |
| p-value † | 0.001 | 0.99 | |||||
| Class C β-lactamase | |||||||
| PDC-3 | 11 (47.8) | 5 (21.7) | 7 (30.4) | 10 (43.5) | 1 (4.3) | 12 (52.2) | 23 |
| PDC-35 | 0 | 13 (86.7) | 2 (13.3) | 0 | 0 | 15 (100) | 15 |
| PDC-7 | 4 (40) | 6 (60) | 0 | 3 (30) | 2 (20) | 5 (50) | 10 |
| PDC-1 | 7 (77.8) | 1 (11.1) | 1 (11.1) | 8 (88.9) | 0 | 1 (11.1) | 9 |
| PDC-5 | 5 (100) | 0 | 0 | 4 (80) | 1 (20) | 0 | 5 |
| PDC-10 | 5 (100) | 0 | 0 | 5 (100) | 0 | 0 | 5 |
| PDC-8 | 1 (33.33) | 1 (33.33) | 1 (33.33) | 2 (66.7) | 0 | 1 (33.33) | 3 |
| PDC-9 | 1 (100) | 0 | 0 | 1 (100) | 0 | 0 | 1 |
| p-value † | <0.001 | <0.001 | |||||
| Class D β-lactamase | |||||||
| OXA-50 | 20 (64.5) | 4 (12.9) | 8 (25.8) | 19 (59.4) | 2 (6.2) | 11 (34.4) | 32 |
| OXA-488 | 12 (42.8) | 15 (53.6) | 2 (7.14) | 10 (34.5) | 0 | 19 (56.5) | 29 |
| OXA-10 | 3 (16.7) | 7 (38.9) | 8 (44.4) | 1 (5.6) | 1 (5.6) | 16 (88.9) | 18 |
| OXA-486 | 6 (54.5) | 4 (36.4) | 1 (9.1) | 6 (54.5) | 1 (9.1) | 4 (36.4) | 11 |
| OXA-4 | 0 | 4 (57.1) | 3 (42.9) | 0 | 1 (14.3) | 6 (85.7) | 7 |
| OXA-114a | 1 (25) | 2 (50) | 1 (25) | 0 | 0 | 4 (100) | 4 |
| OXA-17 | 0 | 3 (100) | 0 | 0 | 0 | 3 (100) | 3 |
| E. coli ampH | 1 (50) | 0 | 1 (50) | 1 (50) | 0 | 1 (50) | 2 |
| OXA-14 | 0 | 1 (100) | 0 | 1 (100) | 0 | 0 | 1 |
| OXA-129 | 0 | 0 | 1 (100) | 0 | 0 | 1 (100) | 1 |
| LCR-1 | 0 | 0 | 1 (100) | 0 | 0 | 1 (100) | 1 |
| p-value † | <0.001 | 0.001 | |||||
| Total of genes | 90 (38.3) | 91 (38.7) | 54 (23) | 80 (34) | 15 (6.4) | 140 (59.6) | 235 |
| Total No. of isolates | 38 (50.6) | 26 (34.7) | 11 (14.7) | 35 (46.7) | 5 (6.6) | 35 (46.7) | 75 |
Results are expressed as number (percentage), † p-value was calculated using the Fisher Exact test to examine the association between the β-lactamase gene and susceptibility patterns (susceptible, resistant, extremely resistant) to ceftazidime–avibactam and ceftolozane–tazobactam.