Epidemiology, Clinical Characteristics and Outcomes of Extensively Drug-Resistant Acinetobacter baumannii Infections among Solid Organ Transplant Recipients

Abstract

BackgroundExtensively drug-resistant Acinetobacter baumannii (XDR-Ab) has emerged as a major nosocomial pathogen, but optimal treatment regimens are unknown. Although solid organ transplant (SOT) recipients are particularly susceptible to XDR-Ab infections, studies in this population are limited. Our objectives were to determine the epidemiology, clinical characteristics and outcomes of XDR-Ab infections among SOT patients.MethodsA retrospective study of SOT recipients at our center who were colonized or infected with XDR-Ab between November 2006 and December 2011 was conducted. Among infected patients, the primary outcome was survival at 28 days. Secondary outcomes included survival at 90 days and clinical success at 28 days, and XDR-Ab infection recurrence.ResultsXDR-Ab was isolated from 69 SOT patients, of whom 41% (28) and 59% (41) were colonized and infected, respectively. Infections were significantly more common among cardiothoracic than abdominal transplant recipients (p = 0.0004). Ninety-eight percent (40/41) of patients had respiratory tract infections, most commonly ventilator-associated pneumonia (VAP; 88% [36/41]). Survival rates at 28 and 90 days were 54% (22/41) and 46% (19/41), respectively. Treatment with a colistin-carbapenem regimen was an independent predictor of 28-day survival (p = 0.01; odds ratio = 7.88 [95% CI: 1.60–38.76]). Clinical success at 28 days was achieved in 49% (18/37) of patients who received antimicrobial therapy, but 44% (8/18) of successes were associated with infection recurrence within 3 months. Colistin resistance emerged in 18% (2/11) and 100% (3/3) of patients treated with colistin-carbapenem and colistin-tigecycline, respectively (p = 0.03).ConclusionsXDR-Ab causes VAP and other respiratory infections following SOT that are associated with significant recurrence and mortality rates. Cardiothoracic transplant recipients are at greatest risk. Results from this retrospective study suggest that colistin-carbapenem combinations may result in improved clinical responses and survival compared to other regimens and may also limit the emergence of colistin resistance.

Carbapenem-Resistant Pseudomonas aeruginosa Bacteremia: Risk Factors for Mortality and Microbiologic Treatment Failure

“…13 (43) 2 (29) 0.68 11 (44) 4 (40) 1.00 Neutropenia, n (%) 2 (7) 1 (14) 0.48 Retained antimicrobial susceptibility and the ability to devise active antimicrobial treatment regimens distinguished our experience with CR P. aeruginosa bacteremia from our previously reported studies of CRE bacteremia (9,(24)(25)(26). Rates of resistance to gentamicin and cefepime among CRE bloodstream infections at our institution were 53% and 100%, respectively, which were higher than the 27% and 32% rates reported here for CR P. aeruginosa (27).…”

Aminoglycosides for Treatment of Bacteremia Due to Carbapenem-Resistant Klebsiella pneumoniae

“…Polymyxins alone or in combination have been linked to suboptimal treatment responses among patients with CR K. pneumoniae infections in another study (25). The emergence of colistin resistance during treatment is a well-recognized limitation of this agent (26)(27)(28). In contrast, aminoglycosides are rapidly and durably bactericidal in vitro (1,2), and the emergence of resistance was uncommon in our clinical experience.…”

Multidrug-resistant Gram-negative bacteria-resistant infections: epidemiology, clinical issues and therapeutic options

“…54 The combination of colistin with a carbapenem for the treatment of MDR A. baumannii infections has been analysed only in retrospective studies suggesting that colistin-carbapenem combinations may result in improved clinical responses and survival compared to other regimens and may also limit the emergence of colistin resistance. 55 The largest comparative study analyzed 250 patients with XDR-Ab BSIs matching colistin monotherapy to combination therapy with colistin + meropenem, col- istin + sulbactam and colistin plus other agents. 56 Outcome in terms of 14-day survival, eradication rate and in-hospital mortality was significantly better among patients receiving combination therapy, although no differences between the 3 different combination regimens were found.…”