Synergistic Effect of Colistin and Rifampin Against Multidrug Resistant Acinetobacter baumannii: A Systematic Review and Meta-Analysis

Abstract

The existence of infections caused by multidrug resistant (MDR) Acinetobacter baumannii is a growing problem because of the difficulty to treat them. We examined the published literature and focused our analysis on the investigation of the synergism of colistin and rifampin against MDR A. baumannii isolates via systematic review and meta-analysis. A systematic literature search was performed using the following 4 databases (PubMed, Scopus, EMBASE and ISI Web of Sciences). The related articles were evaluated during the period from December 2014 to January 2015. Information based on resistance and sensitivity to antibiotics, the minimum inhibitory concentration and the effects of two antibiotics on each other including synergism, antagonism, relative synergism and additive antagonism were extracted. A meta-analysis of 17 studies including 448 samples was brought into process and 2% (95% CI 0-4%) and 72% (95% CI 56-89%) resistance to colistin and rifampin were observed, respectively. 42% of all isolates showed MIC = 4 µg/ml (95% CI 14-69%) to rifampin and 30% MIC= 2 µg/ml to colistin (95% CI 3.8-78%). MIC50 and MIC90 for both rifampin and colistin were 2 µg/ml and 4 µg/ml, respectively. 63% of the strains demonstrated synergy (95% CI 37-90%), 7% were highlighted as relative synergism (95% CI 0.0- 13%), 3% showed an additive effect (95% CI -0.0-7%) and 14% were indifferent (95% CI 6-23%). The antagonistic effect was not observed in this combination. Synergy rates of time-kill assay in rifampin and colistin combinations were generally higher than those of check bored microdilution and E-test method. The results demonstrated that the combination therapy could be more useful when compared to monotherapy and that this strategy might reduce the resistance rate to rifampin in MDR A. baumannii isolates.

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

“…MIC a and MIC b represent the MIC value read from strip A and strip B tests, respectively. A calculated FICI ≤0.5 represented a synergistic effect (22), a value between 0.5-1 represented as an additive effect, a value between 1-4 represented as an indifferent effect, and a value of >4 represented an antagonistic effect (22). Furthermore, the MIC value of each antibiotic was recorded during combination antimicrobial susceptibility tests.…”

Linear Thanatin Is an Effective Antimicrobial Peptide against Colistin-Resistant <i>Escherichia coli in Vitro</i>

“…Combination of antimicrobials offers a potential for increasing antimicrobial treatment efficacy and for reducing resistance evolution [26]. Synergy between colistin and other antibiotics have been reported [27] [28]. We have tested the combinatorial effect of L-thanatin and colistin against colistin-resistant E. coli but only found concentration-dependent additive effect at certain combinations.…”

In vitro activity of colistin in combination with various antimicrobials against <em>Acinetobacter baumannii</em> species, a report from South Iran

“…Although only two isolates were categorized as susceptible to rifampin, this agent showed synergy with colistin against eleven isolates. It has previously been confirmed that rifampin combined with other antimicrobials (such as colistin, imipenem, ceftazidim, and ofloxacin) may be synergic against some MDR Gram-negative bacteria 21,22…”