TABLE 2.
Activities of RX-P873 and comparator antimicrobial agents when tested against 657 Enterobacteriaceae and 402 nonfermentative bacilli
| Organism group (no. tested) and antimicrobial agent | MIC (μg/ml) |
Susceptible/intermediate/resistant (%) according to: |
|||
|---|---|---|---|---|---|
| MIC50 | MIC90 | Range | CLSIa | EUCASTa | |
| Enterobacteriaceae (657)b | |||||
| RX-P873 | 0.25 | 0.5 | 0.06–>32 | ||
| Piperacillin-tazobactam | 2 | 32 | ≤0.5–>64 | 87.5/6.3/6.2 | 83.9/3.6/12.5 |
| Ceftriaxone | 0.06 | >2 | ≤0.015–>2 | 79.6/0.3/20.1 | 79.6/0.3/20.1 |
| Ceftazidime | 0.25 | >16 | ≤0.12–>16 | 82.3/1.9/15.8 | 79.3/3.0/17.7 |
| Cefepime | ≤0.12 | 8 | ≤0.12–>16 | 87.1/3.9/9.0 | 85.5/4.1/10.4 |
| Ciprofloxacin | 0.03 | >8 | ≤0.004–>8 | 83.1/2.0/14.9 | 81.6/1.5/16.9 |
| Colistin | 0.5 | >8 | ≤0.12–>8 | 83.3/0.0/16.7 | |
| Gentamicin | 0.5 | 2 | ≤0.06–>8 | 92.4/0.3/7.3 | 91.0/1.4/7.6 |
| Meropenem | ≤0.06 | ≤0.06 | ≤0.06–>8 | 98.0/0.2/1.8 | 98.2/0.1/1.7 |
| Tigecyclinec | 0.5 | 2 | 0.06–>4 | 97.1/2.6/0.3 | 88.9/8.2/2.9 |
| E. coli (202) | |||||
| RX-P873 | 0.12 | 0.25 | 0.06–2 | ||
| Piperacillin-tazobactam | 2 | 8 | ≤0.5–>64 | 93.1/3.4/3.5 | 90.6/2.5/6.9 |
| Ceftriaxone | 0.06 | >2 | ≤0.015–>2 | 88.6/0.0/11.4 | 88.6/0.0/11.4 |
| Ceftazidime | 0.25 | 2 | ≤0.12–>16 | 93.1/1.0/5.9 | 89.1/4.0/6.9 |
| Cefepime | ≤0.12 | 2 | ≤0.12–>16 | 91.1/1.5/7.4 | 89.1/3.0/7.9 |
| Ciprofloxacin | 0.015 | >8 | 0.008–>8 | 78.2/1.0/20.8 | 77.7/0.5/21.8 |
| Colistin | 0.25 | 0.5 | 0.25–0.5 | 100.0/0.0/0.0 | |
| Gentamicin | 0.5 | 1 | ≤0.06–>8 | 93.1/0.5/6.4 | 92.1/1.0/6.9 |
| Meropenem | ≤0.06 | ≤0.06 | ≤0.06 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| Tigecyclinec | 0.12 | 0.25 | 0.06–1 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| K. pneumoniae (202) | |||||
| RX-P873 | 0.25 | 0.5 | 0.12–2 | ||
| Piperacillin-tazobactam | 2 | 32 | ≤0.5–>64 | 88.1/3.0/8.9 | 83.7/4.4/11.9 |
| Ceftriaxone | 0.06 | >2 | ≤0.015–>2 | 77.7/0.0/22.3 | 77.7/0.0/22.3 |
| Ceftazidime | 0.25 | >16 | ≤0.12–>16 | 76.7/3.5/19.8 | 75.2/1.5/23.3 |
| Cefepime | ≤0.12 | >16 | ≤0.12–>16 | 79.2/4.0/16.8 | 78.7/2.5/18.8 |
| Ciprofloxacin | 0.03 | >8 | 0.008–>8 | 80.2/2.5/17.3 | 79.7/0.5/19.8 |
| Colistin | 0.5 | 1 | 0.25–>8 | 97.5/0.0/2.5 | |
| Gentamicin | 0.25 | >8 | ≤0.06–>8 | 89.1/0.0/10.9 | 87.6/1.5/10.9 |
| Meropenem | ≤0.06 | ≤0.06 | ≤0.06–>8 | 95.1/0.1/5.0 | 95.1/0.4/4.5 |
| Tigecyclinec | 0.5 | 2 | 0.12–4 | 96.5/3.5/0.0 | 88.6/7.9/3.5 |
| E. cloacae (50) | |||||
| RX-P873 | 0.5 | 0.5 | 0.12–1 | ||
| Piperacillin-tazobactam | 4 | >64 | 1–>64 | 70.0/12.0/18.0 | 64.0/6.0/30.0 |
| Ceftriaxone | 1 | >2 | 0.03–>2 | 54.0/0.0/46.0 | 54.0/0.0/46.0 |
| Ceftazidime | 0.5 | >16 | ≤0.12–>16 | 60.0/2.0/38.0 | 54.0/6.0/40.0 |
| Cefepime | ≤0.12 | 8 | ≤0.12–>16 | 76.0/16.0/8.0 | 72.0/14.0/14.0 |
| Ciprofloxacin | 0.015 | 8 | 0.008–>8 | 80.0/6.0/14.0 | 80.0/0.0/20.0 |
| Colistin | 0.5 | 8 | 0.25–>8 | 88.0/0.0/12.0 | |
| Gentamicin | 0.25 | >8 | 0.12–>8 | 88.0/0.0/12.0 | 84.0/4.0/12.0 |
| Meropenem | ≤0.06 | 0.12 | ≤0.06–2 | 98.0/2.0/0.0 | 100.0/0.0/0.0 |
| Tigecyclinec | 0.5 | 2 | 0.25–>4 | 90.0/8.0/2.0 | 84.0/6.0/10.0 |
| E. aerogenes (50) | |||||
| RX-P873 | 0.25 | 0.5 | 0.12–1 | ||
| Piperacillin-tazobactam | 4 | 64 | ≤0.5–>64 | 64.0/32.0/4.0 | 56.0/8.0/36.0 |
| Ceftriaxone | 0.25 | >2 | ≤0.015–>2 | 54.0/0.0/46.0 | 54.0/0.0/46.0 |
| Ceftazidime | 1 | >16 | ≤0.12–>16 | 54.0/2.0/44.0 | 52.0/2.0/46.0 |
| Cefepime | ≤0.12 | 2 | ≤0.12–16 | 92.0/6.0/2.0 | 88.0/10.0/2.0 |
| Ciprofloxacin | 0.015 | 0.5 | 0.008–>8 | 94.0/0.0/6.0 | 90.0/4.0/6.0 |
| Colistin | 0.25 | 0.5 | 0.25–>8 | 96.0/0.0/4.0 | |
| Gentamicin | 0.25 | 1 | 0.12–>8 | 96.0/0.0/4.0 | 96.0/0.0/4.0 |
| Meropenem | ≤0.06 | 0.12 | ≤0.06–0.25 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| Tigecyclinec | 0.5 | 1 | 0.12–4 | 98.0/2.0/0.0 | 92.0/6.0/2.0 |
| C. freundii (51) | |||||
| RX-P873 | 0.25 | 0.5 | 0.12–2 | ||
| Piperacillin-tazobactam | 2 | 64 | ≤0.5–>64 | 82.4/7.8/9.8 | 78.4/4.0/17.6 |
| Ceftriaxone | 0.25 | >2 | 0.06–>2 | 76.5/0.0/23.5 | 76.5/0.0/23.5 |
| Ceftazidime | 0.5 | >16 | 0.25–>16 | 78.4/0.0/21.6 | 72.5/5.9/21.6 |
| Cefepime | ≤0.12 | 4 | ≤0.12–>16 | 88.2/4.0/7.8 | 86.3/5.9/7.8 |
| Ciprofloxacin | 0.06 | 2 | 0.008–>8 | 86.3/3.9/9.8 | 80.4/5.9/13.7 |
| Colistin | 0.5 | 1 | ≤0.12–1 | 100.0/0.0/0.0 | |
| Gentamicin | 0.5 | 1 | 0.12–>8 | 92.2/1.9/5.9 | 90.2/2.0/7.8 |
| Meropenem | ≤0.06 | ≤0.06 | ≤0.06–>8 | 96.1/0.0/3.9 | 96.1/0.0/3.9 |
| Tigecyclinec | 0.25 | 1 | 0.12–2 | 100.0/0.0/0.0 | 92.2/7.8/0.0 |
| Proteus spp. (51)d | |||||
| RX-P873 | 1 | 2 | 0.12–>32 | ||
| Piperacillin-tazobactam | ≤0.5 | ≤0.5 | ≤0.5–4 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| Ceftriaxone | ≤0.015 | 0.06 | ≤0.015–>2 | 96.1/0.0/3.9 | 96.1/0.0/3.9 |
| Ceftazidime | ≤0.12 | ≤0.12 | ≤0.12–8 | 98.0/2.0/0.0 | 96.1/1.9/2.0 |
| Cefepime | ≤0.12 | ≤0.12 | ≤0.12–8 | 96.1/3.9/0.0 | 96.1/1.9/2.0 |
| Ciprofloxacin | 0.03 | 2 | ≤0.004–>8 | 88.2/2.0/9.8 | 86.3/1.9/11.8 |
| Colistin | >8 | >8 | >8 | 0.0/0.0/100.0 | |
| Gentamicin | 0.5 | 2 | 0.12–>8 | 98.0/0.0/2.0 | 96.1/1.9/2.0 |
| Meropenem | ≤0.06 | 0.12 | ≤0.06–0.12 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| Tigecyclinec | 1 | 2 | 0.12–>4 | 92.2/5.8/2.0 | 52.9/39.3/7.8 |
| Serratia marcescens (51) | |||||
| RX-P873 | 0.5 | 0.5 | 0.12–2 | ||
| Piperacillin-tazobactam | 2 | 8 | ≤0.5–64 | 96.1/3.9/0.0 | 94.1/2.0/3.9 |
| Ceftriaxone | 0.25 | 2 | 0.03–>2 | 88.2/4.0/7.8 | 88.2/4.0/7.8 |
| Ceftazidime | 0.25 | 0.5 | ≤0.12–4 | 100.0/0.0/0.0 | 98.0/2.0/0.0 |
| Cefepime | ≤0.12 | 0.25 | ≤0.12–>16 | 98.0/0.0/2.0 | 98.0/0.0/2.0 |
| Ciprofloxacin | 0.06 | 0.12 | 0.015–>8 | 98.0/0.0/2.0 | 94.1/3.9/2.0 |
| Colistin | >8 | >8 | 1–>8 | 9.8/0.0/90.2 | |
| Gentamicin | 0.5 | 1 | 0.12–>8 | 98.0/0.0/2.0 | 98.0/0.0/2.0 |
| Meropenem | ≤0.06 | 0.12 | ≤0.06–0.25 | 100.0/0.0/0.0 | 100.0/0.0/0.0 |
| Tigecyclinec | 1 | 2 | 0.5–4 | 96.1/3.9/0.0 | 80.4/15.7/3.9 |
| P. aeruginosa (200) | |||||
| RX-P873 | 2 | 4 | 0.25–8 | ||
| Piperacillin-tazobactam | 4 | 64 | ≤0.5–>64 | 80.5/11.0/8.5 | 80.5/0.0/19.5 |
| Ceftazidime | 2 | >16 | 0.5–>16 | 83.0/4.0/13.0 | 83.0/0.0/17.0 |
| Cefepime | 2 | 16 | 0.25–>16 | 84.5/10.5/5.0 | 84.5/0.0/15.5 |
| Ciprofloxacin | 0.12 | >8 | 0.008–>8 | 78.0/2.0/20.0 | 76.0/2.0/22.0 |
| Tobramycin | 0.5 | 2 | ≤0.25–>16 | 91.0/1.5/7.5 | 91.0/0.0/9.0 |
| Amikacin | 4 | 8 | ≤0.25–>32 | 93.5/2.0/4.5 | 91.0/2.5/6.5 |
| Meropenem | 0.5 | 8 | ≤0.06–>8 | 76.0/6.0/18.0 | 76.0/14.5/9.5 |
| Colistin | 1 | 2 | 0.25–4 | 99.5/0.5/0.0 | 100.0/0.0/0.0 |
| Acinetobacter baumannii (202) | |||||
| RX-P873 | 0.5 | 1 | 0.12–4 | ||
| Ampicillin-sulbactam | 16 | >32 | 0.5–>32 | 48.0/11.4/40.6 | |
| Ceftazidime | >16 | >16 | 0.5–>16 | 38.1/2.5/59.4 | |
| Cefepime | 16 | >16 | 0.25–>16 | 36.6/13.4/50.0 | |
| Ciprofloxacin | >8 | >8 | 0.06–>8 | 36.1/0.0/63.9 | 36.1/0.0/63.9 |
| Tobramycin | 4 | >16 | ≤0.25–>16 | 53.5/3.4/43.1 | 53.5/0.0/46.5 |
| Amikacin | 8 | >32 | ≤0.25–>32 | 58.4/6.0/35.6 | 53.5/4.9/41.6 |
| Meropenem | >8 | >8 | ≤0.06–>8 | 46.0/1.5/52.5 | 45.5/2.0/52.5 |
| Colistin | 1 | 2 | 0.25–>8 | 97.0/0.0/3.0 | 97.0/0.0/3.0 |
| Tigecycline | 1 | 4 | 0.12–>4 | ||
a
2013 CLSI and EUCAST criteria.
b
Includes Citrobacter freundii (51 strains), Enterobacter aerogenes (50 strains), Enterobacter cloacae (50 strains), Escherichia coli (202 strains), Klebsiella pneumoniae (202 strains), Morganella morganii (11 strains), Proteus mirabilis (30 strains), Proteus vulgaris (4 strains), Providencia rettgeri (4 strains), Providencia stuartii (2 strains), and Serratia marcescens (51 strains).
c
In the absence of a CLSI breakpoint, U.S. FDA breakpoints were applied when available (22).
d
Includes Morganella morganii (11 strains), Proteus mirabilis (30 strains), Proteus vulgaris (4 strains), Providencia rettgeri (4 strains), and Providencia stuartii (4 strains).