MBL Producing Gram-Negative Bacilli from Sputum and Urine acillin/tazobactam and fluoroquinolones were higher among MPs, and overall prior antibiotics exposure was more fre- quent in the INMNP group. These findings are not consis- tent with previous reports,3,16,18 and the discrepancies might be related to our study group which included not only pa- tients with clinical infections but also patients with coloni- zation. In PFGE analysis, two isolates which were obtained 14 Table 2. Comparison between MBL-Producers and MBL-Nonproducers p value MBL-nonproducers n = 164 (93.2) 55.19 112 (68.3) 38.62 MBL-producers n = 12 (6.8) 47.42 7 (58.3) 34.58 Mean age (yrs) 0.353 Male sex 0.529 Hospital stay within 6 months (days)* 0.793 Species Pseudomonas aeruginosa 116 (70.7) 7 (58.3) Acinetobacter baumannii 48 (29.3) 5 (41.7) 0.350 Charlson index (mean) 2.15 2.00 0.803 APACHE II score (mean) 9.79 7.08 0.100 Underlying disease Malignancy 41 (25.0) 4 (33.3) 0.506 Diabetes mellitus 46 (28.0) 2 (16.7) 0.519 Renal disease 24 (14.6) 1 (8.3) 0.455 Cardiac disease 33 (20.2) 2 (16.7) 1.000 Liver cirrhosis 9 (5.5) 0 1.000 Neutropenia 3 (3.1) 0 1.000 Immunosuppression 32 (19.6) 5 (41.7) 0.133 ICU stay 115 (70.1) 3 (25) 0.003 Ventilator care 91 (56.6) 3 (25) 0.034 Previous antibiotics exposure 119 (72.6) 5 (41.7) 0.015 Piperacillin/tazobactam 43 (26.2) 0 0.040 Cefoperazone/sulbactam 29 (17.7) 0 0.220 Aztreonam 2 (1.2) 0 1.000 Fluoroquinolones 63 (38.4) 2 (16.7) 0.215 Aminoglycosides 42 (25.6) 3 (25) 1.000 Glycopeptides 78 (47.6) 3 (25) 0.148 Ceftazidime 15 (9.1) 0 0.603 Carbapenem 56 (34.1) 2 (16.7) 0.341 28-day case-fatality 26 (15.6) 1 (8.3) 0.696 In hospital case-fatality 59 (36.0) 2 (16.7) 0.221 MBL, metallo-β-lactamase; ICU, intensivecareunit. *All hospital stay duration within 6 months prior to imipenem nonsusceptible organism isolation were added including multiple admis- sions. The data are the numbers (%) of patients unless otherwise indicated. Table 3. Susceptibility to Antibiotics Other Than Carbapenem Piperacillin/tazobactam Cefaperazone/sulbactam Aztreonam Fluoroquinolones Aminoglycosides Ceftazidime MBL, metallo-β-lactamase. The data are the numbers (%) of patients unless otherwise indicated. MBL-nonproducers n = 164 (93.2) 27 (16.5) 35 (21.3) 38 (23.2) 20 (12.2) 51 (31.1) 102 (62.2) MBL-producers n = 12 (6.8) 5 (41.7) 4 (33.3) 2 (16.7) 5 (41.7) 5 (41.7) 1 (8.3) p value 0.045 0.305 1.000 0.015 0.524 < 0.001 Yonsei Med J http://www.eymj.org Volume 52 Number 2 March 2011 355