The consequences of an outbreak of multidrug-resistant Pseudomonas aeruginosa among patients treated for critical leg ischemia

Objective

This retrospective matched case-control study evaluated the consequences of multidrug-resistant Pseudomonas aeruginosa (MDR Pa) in critical leg ischemia (CLI) patients treated with infrainguinal bypass surgery (IBS).

Methods

An outbreak of MDR Pa occurred on our vascular surgical ward during a 13-month period. Bacteria cultures positive for MDR Pa were obtained from 129 patients, and 64 CLI patients treated with IBS formed the study group. A control group of 64 was retrospectively matched from MDR Pa-negative patients treated with IBS in the same unit according to sex, age, presence of diabetes, Fontaine class, graft material, and site of the distal anastomosis. The most frequent sites of initial positive MDR Pa culture were the incisional wound in 30 (47%) and ischemic ulcer in 23 (36%). Median time between the positive MDR Pa-culture and IBS was 14 days (range, 56 days pre-IBS to 246 days post-IBS). Graft patency, survival, leg salvage, and amputation-free survival were assessed.

Results

One-year amputation-free survival (± standard error) was 52% ± 6% in the MDR Pa group vs 75% ± 5% in the control group (P = .02). Five-year amputation-free survival was 29% ± 6% in the MDR Pa group and 32% ± 6% in the control group (P = .144). For MDR Pa and control groups, the 1-year survival was 69% ± 6% and 82% ± 5% (P = .063), respectively, and 5-year survival was 36% ± 6% and 36% ± 6% (P = .302), respectively. For the MDR Pa and control groups, leg salvage was 79% ± 5% and 92% ± 4% at 1 year (P = .078) and 73% ± 7% and 87% ± 5% at 5 years (P = .126), respectively. The overall secondary patency rate at 1 year was 72% ± 7% in the MDR Pa group vs 81% ± 6% in the control group (P = .149). Local wound surgery was more frequent in MDR Pa patients than in controls (P = .002).

Conclusions

The MDR Pa outbreak was associated with a decreased short-term amputation-free survival after IBS for CLI in patients with positive MDR Pa culture. The potential risks of MDR Pa should be seriously considered whenever a positive culture is obtained in a vascular patient with CLI.