Effectiveness of tigecycline-based versus colistin- based therapy for treatment of pneumonia caused by multidrug-resistant Acinetobacter baumanniiin a critical setting: a matched cohort analysis

Abstract

BackgroundColistin and tigecycline have both been shown good in vitro activity among multi-drug resistant Acinetobacter baumannii (MDRAB). A comparative study of colistin versus tigecycline for MDRAB pneumonia is lacking.MethodsThe study enrolled adults with MDRAB pneumonia admitted to intensive care units at a referral medical center during 2009–2010. Since there were no standardized minimum inhibitory concentration (MIC) interpretation criteria of tigecycline against A. baumannii, MIC of tigecycline was not routinely tested at our hospital. During the study periods, MIC of colistin was not routinely tested also. We consider both colistin and tigecycline as definite treatments of MDRAB pneumonia. Patients who received tigecycline were selected as potential controls for those who had received colistin. We performed a propensity score analysis, by considering the criteria of age, gender, underlying diseases, and disease severity, in order to match and equalize potential prognostic factors and severity in the two groups.ResultsA total of 294 adults with MDRAB pneumonia were enrolled, including 119 who received colistin and 175 who received tigecycline. We matched 84 adults who received colistin with an equal number of controls who received tigecycline. The two well matched cohorts share similar characteristics: the propensity scores are colistin: 0.37 vs. tigecycline: 0.37, (P = .97); baseline creatinine (1.70 vs. 1.81, P = .50), and the APACHE II score (21.6 vs. 22.0, P = .99). The tigecycline group has an excess mortality of 16.7% (60.7% vs. 44%, 95% confidence interval 0.9% – 32.4%, P = .04). The excess mortality of tigecycline is significant only among those with MIC >2 μg/mL (10/12 vs. 37/84, P = .01), but not for those with MIC ≦ 2 μg/mL (4/10 vs. 37/84, P = .81).ConclusionsOur data disfavors the use of tigecycline-based treatment in treating MDRAB pneumonia when tigecycline and colistin susceptibilities are unknown, since choosing tigecycline-based treatment might result in higher mortality. The excess mortality of tigecycline-based group may be related to higher MIC of tigecycline (> 2 μg/mL). Choosing tigecycline empirically for treating MDRAB pneumonia in the critical setting should be cautious.

In vitro assessment of cefoperazone-sulbactam based combination therapy for multidrug-resistant Acinetobacter baumannii isolates in China

“…Notwithstanding, combination therapy has been considered superior to single-drug therapy against MDRAB, with regards to both efficacy and lower risk of adverse reactions and drug toxicity (9)(10)(11). Tigecycline based therapy with various combinations such as cefoperazone-sulbactam, carbapenem, quinolone, or aminoglycoside antibiotics, has been adopted for treatment of MDRAB infections (12,13). However, the most effective combination therapy to treat A. baumannii infection has yet to be explored.…”

Risk factors for hospital infections caused by carbapanem-resistant Acinetobacter baumannii

“…An important example of such a microorganism is Acinetobacter baumannii (A. baumannii), which rapidly develops resistance to multiple antimicrobial drugs [1]. A. baumannii became a major causative agent of severe, life-threatening HIs such as pneumonia, wound infections, meningitis, urinary tract infections, central venous catheter-related infections, and bacteremia, especially in intensive care units (ICUs) [2][3][4][5].…”

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

“…In particular, retrospective clinical data validate the susceptibility breakpoint of tigecycline at 2 g/ml. Specifically, infections caused by Acinetobacter strains with tigecycline MICs of Ն2 g/ml result in significantly increased mortality when treated with tigecycline (137,(233)(234)(235). Even if the MIC is Յ2 g/ml, Acinetobacter bacteremia may have inferior outcomes when treated with tigecycline, including worse survival, failure to clear bacteremia, and development of breakthrough bacteremia (236).…”