Table 1.
Activity in vitro of PTS, PTSO, and others antibacterial agents against gram-negative organisms.
| Organisms (number of isolates) | MIC 50 | MIC 90 | MBC 50 | MBC 90 | % of resistant isolates |
|---|---|---|---|---|---|
| (in mg/L) | (in mg/L) | (in mg/L) | (in mg/L) | ||
| Enterobacteriaceae (n=151) | |||||
| Amoxicillin/clavulanate | 32/16 | 256/128 | 64/32 | 256/128 | 59.6 |
| Piperacillin/tazobactam | 8/4 | 256/4 | 32/4 | 512/4 | 31.8 |
| Cefuroxime | >512 | >512 | >512 | >512 | 81.5 |
| Cefoxitin | 8 | 256 | 64 | 512 | 37.1 |
| Cefotaxime | 64 | >128 | 128 | >128 | 77.5 |
| Ceftazidime | 16 | 256 | 64 | 512 | 58.3 |
| Cefepime | 8 | 128 | 32 | 256 | 65.6 |
| Imipenem | 1 | 1 | 2 | 16 | 2.0 |
| Meropenem | 0.125 | 1 | 0.25 | 4 | 1.3 |
| Gentamicin | 4 | 128 | 32 | >128 | 35.8 |
| Tobramycin | 4 | 128 | 32 | >128 | 42.4 |
| Amikacin | 16 | >512 | 64 | >512 | 29.1 |
| Ciprofloxacin | 64 | >128 | 128 | >128 | 67.6 |
| Trimethoprim/sulfamethoxazole | 2/38 | >64/1216 | 64/1216 | >64/1216 | 53.0 |
| Nitrofurantoín | 32 | 256 | 128 | 512 | 43.0 |
| PTS | 256 | 512 | 256 | 512 | - |
| PTSO | 64 | 128 | 128 | 512 | - |
| Escherichia coli (n=68) | |||||
| Amoxicillin/clavulanate | 16/8 | 256/128 | 64/32 | >256/128 | 55.9 |
| Piperacillin/tazobactam | 8/4 | 128/4 | 32/4 | 256/4 | 26.5 |
| Cefuroxime | >512 | >512 | >512 | >512 | 95.6 |
| Cefoxitin | 8 | 128 | 32 | 256 | 33.8 |
| Cefotaxime | 128 | >128 | >128 | >128 | 94.1 |
| Ceftazidime | 32 | 256 | 64 | >512 | 75.0 |
| Cefepime | 16 | 128 | 64 | 256 | 80.9 |
| Imipenem | 0.5 | 1 | 2 | 4 | 0.0 |
| Meropenem | 0.06 | 1 | 0.125 | 4 | 0.0 |
| Gentamicin | 4 | 64 | 16 | 128 | 30.9 |
| Tobramycin | 4 | 64 | 16 | 128 | 33.8 |
| Amikacin | 8 | 32 | 32 | 128 | 14.7 |
| Ciprofloxacin | 64 | 128 | 128 | >128 | 73.5 |
| Trimethoprim/sulfamethoxazole | >64/1216 | >64/1216 | >64/1216 | >64/1216 | 61.8 |
| Nitrofurantoin | 32 | 64 | 64 | 256 | 14.7 |
| PTS | 128 | 256 | 256 | 512 | - |
| PTSO | 64 | 128 | 128 | 512 | - |
| Klebsiella spp. (n=39) | |||||
| Amoxicillin/clavulanate | 32/16 | 64/32 | 64/32 | 256/128 | 82.1 |
| Piperacillin/tazobactam | 32/4 | 512/4 | 64/4 | >512/4 | 59.0 |
| Cefuroxime | >512 | >512 | >512 | >512 | 97.4 |
| Cefoxitin | 32 | 512 | 64 | >512 | 53.8 |
| Cefotaxime | 64 | >128 | 128 | >128 | 97.4 |
| Ceftazidime | 64 | 256 | 128 | 512 | 76.9 |
| Cefepime | 16 | 64 | 32 | 256 | 79.5 |
| Imipenem | 1 | 1 | 2 | 4 | 0.0 |
| Meropenem | 0.06 | 0.25 | 0.125 | 1 | 0.0 |
| Gentamicin | 64 | >128 | 64 | >128 | 66.7 |
| Tobramycin | 32 | >128 | 32 | >128 | 76.9 |
| Amikacin | 64 | >512 | 128 | >512 | 53.8 |
| Ciprofloxacin | 128 | >128 | >128 | >128 | 87.2 |
| Trimethoprim/sulfamethoxazole | >64/1216 | >64/1216 | >64/1216 | >64/1216 | 79.5 |
| Nitrofurantoin | 64 | 128 | 128 | 256 | 61.5 |
| PTS | 256 | 512 | 256 | 512 | - |
| PTSO | 128 | 256 | 128 | 512 | - |
| ESBL-producers (n=59) | |||||
| Amoxicillin/clavulanate | 16/8 | >256/128 | 64/32 | >256/128 | 52.5 |
| Piperacillin/tazobactam | 8/4 | 256/4 | 32/4 | 512/4 | 30.5 |
| Cefuroxime | >512 | >512 | >512 | >512 | 100 |
| Cefoxitin | 8 | 64 | 32 | 128 | 25.4 |
| Cefotaxime | 128 | >128 | >128 | >128 | 100 |
| Ceftazidime | 64 | 256 | 256 | >512 | 78.0 |
| Cefepime | 32 | 128 | 64 | >256 | 93.2 |
| Imipenem | 0.5 | 1 | 2 | 4 | 0.0 |
| Meropenem | 0.125 | 1 | 0.25 | 4 | 0.0 |
| Gentamicin | 4 | 128 | 16 | >128 | 37.3 |
| Tobramycin | 4 | 128 | 32 | >128 | 47.5 |
| Amikacin | 16 | 128 | 64 | 128 | 25.4 |
| Ciprofloxacin | 64 | >128 | 128 | >128 | 74.6 |
| Trimethoprim/sulfamethoxazole | >64/1216 | >64/1216 | >64/1216 | >64/1216 | 62.7 |
| Nitrofurantoin | 32 | 128 | 64 | 256 | 32.2 |
| PTS | 128 | 256 | 256 | 512 | - |
| PTSO | 64 | 128 | 128 | 512 | - |
| Salmonella spp. and Yersinia spp. (n=32) | |||||
| Amoxicillin/clavulanate | 8/4 | 256/128 | 64/32 | 256/128 | 28.1 |
| Piperacillin/tazobactam | 2/4 | 128/4 | 16/4 | 128/4 | 12.5 |
| Cefuroxime | 4 | >512 | 32 | >512 | 25.0 |
| Cefoxitin | 8 | 64 | 64 | 128 | 12.5 |
| Cefotaxime | 1 | 1 | 8 | 64 | 12.5 |
| Ceftazidime | 4 | 4 | 16 | 64 | 0.0 |
| Cefepime | 2 | 32 | 16 | 64 | 0.0 |
| Imipenem | 1 | 1 | 16 | 16 | 0.0 |
| Meropenem | 1 | 1 | 4 | 8 | 0.0 |
| Gentamicin | 4 | 4 | 32 | 32 | 3.1 |
| Tobramycin | 4 | 4 | 32 | 32 | 6.3 |
| Amikacin | 16 | 128 | 128 | 256 | 34.4 |
| Ciprofloxacin | 1 | 128 | 8 | 128 | 37.5 |
| Trimethoprim/sulfamethoxazole | 2/38 | 2/38 | 16/304 | >64/1216 | 3.1 |
| Nitrofurantoin | 256 | 512 | 512 | 1024 | 65.6 |
| PTS | 256 | 256 | 256 | 512 | - |
| PTSO | 64 | 128 | 64 | 128 | - |
| Remaining enterobacteria (n=12) | |||||
| Amoxicillin/clavulanate | 64/32 | 128/64 | 256/128 | 256/128 | 91.7 |
| Piperacillin/tazobactam | 4/4 | 64/4 | 8/4 | 256/4 | 25.0 |
| Cefuroxime | >512 | >512 | >512 | >512 | 100 |
| Cefoxitin | 256 | >512 | 256 | >512 | 66.7 |
| Cefotaxime | 64 | >128 | 128 | >128 | 91.7 |
| Ceftazidime | 8 | 128 | 32 | 512 | 58.3 |
| Cefepime | 8 | 64 | 8 | 256 | 66.7 |
| Imipenem | 1 | 4 | 2 | 16 | 25.0 |
| Meropenem | 0.06 | 1 | 0.125 | 4 | 16.7 |
| Gentamicin | 4 | 32 | 32 | >128 | 50.0 |
| Tobramycin | 8 | 32 | 16 | >128 | 58.3 |
| Amikacin | 4 | 256 | 8 | >512 | 16.7 |
| Ciprofloxacin | 1 | >128 | 8 | >128 | 50.0 |
| Trimethoprim/sulfamethoxazole | 2/38 | >64/1216 | 16/304 | >64/1216 | 50.0 |
| Nitrofurantoin | 64 | >1024 | 128 | >1024 | 83.3 |
| PTS | 128 | 256 | 256 | 256 | - |
| PTSO | 64 | 128 | 128 | 256 | - |
| Nonfermenting gram-negative bacilli (n=61) | |||||
| Piperacillin/tazobactam | 16/4 | 512/4 | 128/4 | 512/4 | 34.4 |
| Ceftazidime | 8 | 128 | 64 | 512 | 32.8 |
| Cefepime | 8 | 32 | 64 | 256 | 42.6 |
| Imipenem | 16 | 128 | 32 | >128 | 52.5 |
| Meropenem | 4 | 64 | 16 | 128 | 52.5 |
| Gentamicin | 4 | >128 | 32 | >128 | 39.3 |
| Tobramycin | 4 | >128 | 32 | >128 | 27.9 |
| Amikacin | 8 | 128 | 32 | 256 | 19.7 |
| Ciprofloxacin | 32 | >128 | 64 | >128 | 59.0 |
| PTS | 1024 | 2048 | 1024 | 2048 | - |
| PTSO | 256 | 1024 | 512 | 2048 | - |
| Pseudomonas aeruginosa (n=40) | |||||
| Piperacillin/tazobactam | 16/4 | 256/4 | 128/4 | 256/4 | 25.0 |
| Ceftazidime | 8 | 64 | 64 | 256 | 27.5 |
| Cefepime | 8 | 32 | 64 | 128 | 32.5 |
| Imipenem | 16 | 128 | 32 | 128 | 57.5 |
| Meropenem | 4 | 64 | 32 | 128 | 57.5 |
| Gentamicin | 4 | >128 | 16 | >128 | 37.5 |
| Tobramycin | 4 | 128 | 16 | >128 | 17.5 |
| Amikacin | 8 | 32 | 32 | 128 | 12.5 |
| Ciprofloxacin | 32 | >128 | 64 | >128 | 62.5 |
| PTS | 1024 | 2048 | 2048 | 2048 | - |
| PTSO | 512 | 1024 | 512 | 2048 | - |
| Remaining nonfermenting gram-negative bacilli (n=21) | |||||
| Piperacillin/tazobactam | 128/4 | 512/4 | 512/4 | >512/4 | 52.4 |
| Ceftazidime | 8 | 128 | 64 | 512 | 42.9 |
| Cefepime | 16 | 64 | 128 | 256 | 61.9 |
| Imipenem | 2 | >128 | 16 | >128 | 42.9 |
| Meropenem | 2 | 16 | 8 | >128 | 42.9 |
| Gentamicin | 4 | >128 | 32 | >128 | 42.9 |
| Tobramycin | 4 | >128 | 32 | >128 | 47.6 |
| Amikacin | 16 | 256 | 64 | 256 | 33.3 |
| Ciprofloxacin | 4 | >128 | 32 | >128 | 52.4 |
| PTS | 128 | 512 | 128 | 512 | - |
| PTSO | 64 | 256 | 64 | 256 | - |
MIC: minimum inhibitory concentration; MBC: minimum bactericidal concentration; % of resistant isolates: percentages of isolates intermediate or resistant according to the criteria published by the CLSI (2016).