TABLE 2.
Isolates included in each phase of the study
| Organism | Phase 1 | Phase 2 | No. of isolates not susceptible to ATM-CZAa |
|---|---|---|---|
| Citrobacter amalonaticus | 0 | 1 | 0 |
| Citrobacter freundii | 2 | 1 | 0 |
| Citrobacter koseri | 1 | 0 | 0 |
| Enterobacter aerogenes | 5 | 0 | 0 |
| Enterobacter cloacae complex | 7 | 8 | 1 |
| Escherichia coli | 16b | 23 | 4 |
| Klebsiella oxytoca | 2 | 1 | 0 |
| Klebsiella ozaenae | 1 | 0 | 0 |
| Klebsiella pneumoniae | 14b | 35 | 1 |
| Myroides sp. | 0 | 1 | 1 |
| Morganella morganii | 1 | 0 | 0 |
| Proteus mirabilis | 1 | 2 | 0 |
| Providencia rettgeri | 1 | 2 | 1 |
| Providencia sp. | 1 | 1 | 0 |
| Pseudomonas aeruginosa | 0 | 25 | 14 |
| Salmonella spp. | 4 | 0 | 0 |
| Serratia spp. | 4 | 1 | 0 |
| Shigella sonnei | 1 | 0 | 0 |
| Stenotrophomonas maltophilia | 0 | 46 | 2 |
| Total | 61 | 147 | 24 |
a
Not susceptible (NS; intermediate and resistant, >6/6/4 μg/mL) to ATM-CZA. ATM, aztreonam; CZA, ceftazidime-avibactam.
b
One E. coli isolate was excluded due to missing BMD data, and one K. pneumoniae isolate was excluded due to no reference result as the comparator (i.e., disagreement between test sites and repeats).