TABLE 1.
MIC distributions for 64 Enterobacterales isolates tested against ceftazidime-avibactam, aztreonam, and aztreonam-avibactam: AR Lab Network, March 2019 to December 2020
| Isolate categories | Antimicrobial agenta | No. of isolates at each MIC (μg/ml) for each antimicrobial agentb |
MIC50c | MIC90c | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.03 | 0.06 | 0.12 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | 64 | >64 | ||||
| All (64) | CZA | 64 | >64/4 | >64/4 | ||||||||||||
| ATM | 2 | 1 | 1 | 3 | 4 | 4 | 8 | 41 | >64 | >64 | ||||||
| AZA | 7 | 7 | 11 | 13 | 7 | 1 | 9 | 7 | 2 | 0.5/4 | 8/4 | |||||
| Escherichia coli (28) | CZA | 28 | >64/4 | >64/4 | ||||||||||||
| ATM | 1 | 3 | 2 | 3 | 19 | >64 | >64 | |||||||||
| AZA | 1 | 4 | 3 | 2 | 1 | 8 | 7 | 2 | 4/4 | 8/4 | ||||||
| NDM (27) | CZA | 27 | >64/4 | >64/4 | ||||||||||||
| ATM | 1 | 3 | 2 | 3 | 18 | >64 | >64 | |||||||||
| AZA | 1 | 4 | 3 | 2 | 1 | 8 | 6 | 2 | 4/4 | 8/4 | ||||||
| NDM & OXA-48-like (1) | CZA | 1 | ||||||||||||||
| ATM | 1 | |||||||||||||||
| AZA | 1 | |||||||||||||||
| Klebsiella pneumoniae (24) | CZA | 24 | >64/4 | >64/4 | ||||||||||||
| ATM | 1 | 1 | 5 | 17 | >64 | >64 | ||||||||||
| AZA | 3 | 2 | 8 | 8 | 2 | 1 | 0.25/4 | 1/4 | ||||||||
| NDM (17) | CZA | 17 | >64/4 | >64/4 | ||||||||||||
| ATM | 1 | 4 | 12 | >64 | >64 | |||||||||||
| AZA | 2 | 2 | 7 | 4 | 1 | 1 | 0.25/4 | 1/4 | ||||||||
| NDM & OXA-48-like (7) | CZA | 7 | ||||||||||||||
| ATM | 1 | 1 | 5 | |||||||||||||
| AZA | 1 | 1 | 4 | 1 | ||||||||||||
| Enterobacter cloacae complex, NDM (10) | CZA | 10 | >64/4 | >64/4 | ||||||||||||
| ATM | 2 | 2 | 1 | 5 | 32 | >64 | ||||||||||
| AZA | 2 | 1 | 3 | 1 | 3 | 0.25/4 | 1/4 | |||||||||
| Morganella morganii, NDM & KPC (1) | CZA | 1 | ||||||||||||||
| ATM | 1 | |||||||||||||||
| AZA | 1 | |||||||||||||||
| Proteus mirabilis, NDM (1) | CZA | 1 | ||||||||||||||
| ATM | 1 | |||||||||||||||
| AZA | 1 | |||||||||||||||
a
ATM, aztreonam; AZA, aztreonam-avibactam; CZA, ceftazidime-avibactam. Avibactam is at a constant concentration of 4 μg/ml when in combination.
b
Gray shading indicates the not susceptible ranges for CZA and ATM. AZA does not have interpretive criteria.
c
MIC50 and MIC90 were calculated only for groups with >9 isolates.