Table I
Culture source and clinical characteristics of patients infected with multidrug-resistant and non-multidrug-resistant Pseudomonas aeruginosa.
| Demographic parameter | No. of isolates (%) | p-value | |
|---|---|---|---|
| Non-multidrug-resistant P. aeruginosa (n = 63) | Multidrug-resistant P. aeruginosa* (n = 37) | ||
| Male gender | 44 (69.8) | 27 (73.0) | 0.916 |
| Age groups (years) | 0.291 | ||
| < 18 | 7 (11.1) | 1 (2.7) | |
| 18–64 | 23 (36.5) | 13 (35.1) | |
| ≥ 65 | 33 (52.4) | 23 (62.2) | |
| ICU admission | 9 (14.3) | 8 (21.6) | 0.505 |
| Surgical department† | 25 (39.7) | 13 (35.1) | 0.811 |
| Clinical specimen | 1.000 | ||
| Respiratory | 31 (49.2) | 22 (59.5) | |
| Genitourinary | 16 (25.3) | 9 (24.3) | |
| Skin and soft tissue | 10 (15.9) | 6 (16.2) | |
| Gastrointestinal | 3 (4.8) | 0 (0) | |
| Blood | 1 (1.6) | 0 (0) | |
| Bone and joint | 2 (3.2) | 0 (0) | |
| Treatment characteristic | |||
| ≥ 1 active agentx‡ | 45 (71.4) | 21 (56.8) | 0.202 |
| Use of carbapenem | 11 (17.5) | 18 (48.6) | 0.002 |
| Use of colistin | 3 (4.8) | 10 (27.0) | 0.004 |
| Clinical success | 54 (85.7) | 24 (64.9) | 0.029 |
| Death attributable to P. aeruginosa | 6 (9.5) | 10 (27.0) | 0.043 |
1* Multidrug-resistant P. aeruginosa was defined as non-susceptible to ≥ 1 agent in ≥ 3 antimicrobial categories, which included penicillin combinations (piperacillin-tazobactam), cephalosporins (ceftazidime or cefepime), carbapenems (imipenem or meropenem), monobactams (aztreonam), aminoglycosides (amikacin or gentamicin), quinolones (levofloxacin or ciprofloxacin), and polymyxins (colistin).
Table II
In vitro antimicrobial activity against Pseudomonas aeruginosa isolates including total and multidrug-resistant strains.
| Organism/antimicrobial | MIC50 (mg/l) | MIC90 (mg/l) | MIC range (mg/l) | % S |
|---|---|---|---|---|
| P. aeruginosa (n = 100) | ||||
| Amikacin | ≤ 2 | 16 | ≤ 2 to ≥ 64 | 93 |
| Gentamicin | ≤ 1 | 8 | ≤ 1 to ≥ 16 | 87 |
| Aztreonam | 8 | ≥ 64 | ≤ 1 to ≥ 64 | 82 |
| Ciprofloxacin | ≤ 0.25 | ≥ 4 | ≤ 0.25 to ≥ 4 | 68 |
| Ceftazidime-avibactam | 4 | 8 | ≤ 1 to ≥ 128 | 95 |
| Ceftazidime | 4 | 32 | ≤ 1 to ≥ 128 | 76 |
| Cefepime | 2 | 32 | ≤ 1 to ≥ 64 | 82 |
| Imipenem | 2 | ≥ 16 | ≤ 0.25 to ≥ 16 | 76 |
| Meropenem | 0.5 | ≥ 16 | ≤ 0.25 to ≥ 16 | 75 |
| Piperacillin-tazobactam | 8 | ≥ 128 | ≤ 4 to ≥ 128 | 72 |
| Colistin | 1 | 2 | ≤ 0.5 to ≥ 128 | 91 |
| MDR P. aeruginosa (n = 37) | ||||
| Amikacin | 4 | ≥ 64 | ≤ 2 to ≥ 64 | 81.1 |
| Gentamicin | 4 | ≥ 16 | < 1 to ≥ 16 | 37.6 |
| Aztreonam | 16 | ≥ 64 | ≤ 1 to ≥ 64 | 21.6 |
| Ciprofloxacin | ≥ 4 | ≥ 4 | ≤ 0.25 to ≥ 4 | 24.3 |
| Ceftazidime-avibactam | 4 | 16 | ≤ 1 to ≥ 128 | 86.5 |
| Ceftazidime | 16 | 128 | 2 to ≥ 128 | 45.9 |
| Cefepime | 8 | ≥ 64 | ≤ 1 to ≥ 64 | 51.4 |
| Imipenem | ≥ 16 | ≥ 16 | 1 to ≥ 16 | 43.2 |
| Meropenem | 8 | ≥ 16 | ≤ 0.25 to ≥ 16 | 37.8 |
| Piperacillin-tazobactam | 64 | ≥ 128 | ≤ 4 to ≥ 128 | 27.0 |
| Colistin | 1 | 4 | ≤ 0.5 to ≥ 128 | 89.2 |
Table III
In vitro antimicrobial activity against Pseudomonas aeruginosa isolates including carbapenem-resistant and difficult-to-treat strains.
| Organism/antimicrobial | MIC50 (mg/l) | MIC90 (mg/l) | MIC range (mg/l) | % S |
|---|---|---|---|---|
| CR P. aeruginosa (n = 27) | ||||
| Amikacin | 4 | ≥ 64 | ≤ 2 to ≥ 64 | 74.1 |
| Gentamicin | 2 | ≥ 16 | ≤ 1 to ≥ 16 | 66.7 |
| Aztreonam | 16 | ≥ 64 | ≤ 1 to ≥ 64 | 25.9 |
| Ciprofloxacin | ≥ 4 | ≥ 4 | ≤ 0.25 to ≥ 4 | 29.6 |
| Ceftazidime-avibactam | 4 | 16 | ≤ 1 to ≥ 128 | 85.2 |
| Ceftazidime | 8 | 64 | 2 to ≥ 128 | 51.9 |
| Cefepime | 8 | ≥ 64 | ≤ 1 to ≥ 64 | 51.9 |
| Imipenem | ≥ 16 | ≥ 16 | 2 to ≥ 16 | 11.1 |
| Meropenem | ≥ 16 | ≥ 16 | 0.5 to ≥ 16 | 7.4 |
| Piperacillin-tazobactam | 32 | ≥ 128 | ≤ 4 to ≥ 128 | 44.4 |
| Colistin | 1 | 4 | ≤ 0.5 to ≥ 128 | 88.9 |
| DTR P. aeruginosa (n = 9) | ||||
| Amikacin | ≥ 64 | ≥ 64 | ≤ 2 to ≥ 64 | 33.3 |
| Gentamicin | ≥ 16 | ≥ 16 | 2 to ≥ 16 | 33.3 |
| Aztreonam | 32 | ≥ 64 | 16 to ≥ 64 | 0 |
| Ciprofloxacin | ≥ 4 | ≥ 4 | ≥ 4 to ≥ 4 | 0 |
| Ceftazidime-avibactam | 4 | ≥ 128 | ≤ 1 to ≥ 128 | 66.7 |
| Ceftazidime | 64 | ≥ 128 | 16 to ≥ 128 | 0 |
| Cefepime | 32 | ≥ 64 | 16 to ≥ 64 | 0 |
| Imipenem | ≥ 16 | ≥ 16 | 8 to ≥ 16 | 0 |
| Meropenem | ≥ 16 | ≥ 16 | 8 to ≥ 16 | 0 |
| Piperacillin-tazobactam | ≥ 128 | ≥ 128 | 32 to ≥ 128 | 0 |
| Colistin | 1 | 8 | ≤ 0.5 to 8 | 77.8 |
Fig. 1.
Comparisonof susceptibilitiesto selected agents between meropenem-susceptible and meropenem-non-susceptible Pseudomonas aeruginosa isolates. Black bars indicate meropenem-susceptible strains, while gray bars represent meropenem-non-susceptible strains.
Table IV
Characteristics and antimicrobial susceptibility profiles of carbapenemase-producing Pseudomonas aeruginosa isolates.
| Characteristics | PA-57 | PA-16 | PA-28 | PA-40 |
|---|---|---|---|---|
| Carbapenemase | IMP | IMP + KPC | KPC | KPC |
| Clinical specimen | Genitourinary | Genitourinary | Genitourinary | Respiratory |
| MIC Values (mg/l) | ||||
| Amikacin | ≥ 64 | ≥ 64 | 4 | ≤ 2 |
| Gentamicin | ≥ 16 | ≥ 16 | 4 | 2 |
| Aztreonam | 32 | 32 | ≥ 64 | ≥ 64 |
| Ciprofloxacin | ≥ 4 | ≥ 4 | ≥ 4 | ≥ 4 |
| Ceftazidime-avibactam | ≥ 128 | ≥ 128 | 8 | 16 |
| Ceftazidime | ≥ 128 | ≥ 128 | 16 | 64 |
| Cefepime | ≥ 64 | 32 | ≥ 64 | 16 |
| Imipenem | ≥ 16 | ≥ 16 | ≥ 16 | ≥ 16 |
| Meropenem | ≥ 16 | ≥ 16 | ≥ 16 | ≥ 16 |
| Piperacillin-tazobactam | ≥ 128 | ≥ 128 | ≥ 128 | ≥ 128 |
| Colistin | ≤ 0.5 | 1 | 2 | 8 |