In vitro effect of minocycline and colistin combinations on imipenem-resistant Acinetobacter baumannii clinical isolates

Tan, Thean Yen; Ng, Lily Siew Yong; Tan, Eugene K. B.; Huang, G T

doi:10.1093/jac/dkm178

Cited by 77 publications

(65 citation statements)

References 11 publications

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“…As it was previously mentioned, in heteroresistant isolates both COL-RIF and COL-IMI combinations were synergistic in inhibition of regrowth (Table 2). Similar findings were obtained with the colistinminocycline associations [17]. Few synergy studies have been conducted in A. baumannii COL resistant strains.…”

Section: Discussionsupporting

confidence: 83%

In vitro antimicrobials activity against endemic Acinetobacter baumannii multiresistant clones

Rodríguez

Ambrosio

Bajuk

et al. 2010

J Infect Dev Ctries

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Background: Multidrug-resistant strains of Acinetobacter baumannii have been reported increasingly around the world. The administration of an association of antibiotics has been proposed to create an active combination and to prevent the emergence of resistance. Methodology: The activity of colistin, rifampicin, gentamicin, imipenem and their associations was evaluated by means of killing curves in fourteen isolates belonging to three endemic PFGE types, in a university hospital of Buenos Aires city. The 14 isolates were selected on the basis of different mechanisms responsible for resistance to carbapenems and different susceptibility to colistin. Results: The mechanism responsible for the resistance to imipenem was the production of OXA-23 and OXA-58 carbapenemases. Heteroresistance to colistin was observed in six isolates. The associations colistin-rifampicin and colistin-imipenem were synergistic in heteroresistant isolates and prevented the development of colistin-resistant mutants. The association imipenem-gentamicin was bactericidal in gentamicin susceptible isolates, whereas the association imipenem-rifampicin was always indifferent. Conclusion: The antimicrobial activity and the presence of synergy are related to the antimicrobials' susceptibilities irrespective of the PFGE type or the OXA-carbapenemase produced.

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Section: Discussionsupporting

confidence: 83%

In vitro antimicrobials activity against endemic Acinetobacter baumannii multiresistant clones

Rodríguez

Ambrosio

Bajuk

et al. 2010

J Infect Dev Ctries

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“…There are several reports in the literature of synergy studies performed with multidrug-resistant Acinetobacter baumannii (14,15,19). However, the synergy findings were not universal and may have been strain dependent (17), making it difficult to generalize the results.…”

Section: Discussionmentioning

confidence: 99%

“…There is some literature exploring combination antimicrobial therapy in the treatment of multidrug-resistant strains of Acinetobacter baumannii and Pseudomonas aeruginosa (8,14,15,17,19,21). However, there are limited data on combination therapy for KPC-producing K. pneumoniae.…”

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confidence: 99%

In Vitro Evaluation of Antibiotic Synergy for Polymyxin B-Resistant Carbapenemase-Producing Klebsiella pneumoniae

Elemam¹,

Rahimian²,

Doymaz

2010

J Clin Microbiol

116

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Since carbapenemase-producing Klebsiella pneumoniae strains were first reported in North Carolina, these highly resistant organisms have been isolated with increasing frequency, especially in the New York City area. Polymyxin B is one of the few antimicrobials that retain reliable activity against these organisms. However, polymyxin B MICs are elevated against K. pneumoniae isolates with increasing frequency, leaving clinicians with few therapeutic options. We investigated several antimicrobial agents for potential synergy with polymyxin B against 12 clinical strains of carbapenemase-producing K. pneumoniae. A broth microdilution assay using a 96-well plate was developed in which graded dilutions of polymyxin B and the study drug were incubated with resistant isolates in a checkerboard pattern. Polymyxin B was studied in combination with cefazolin, ceftriaxone, cefepime, imipenem, gentamicin, tigecycline, doxycycline, and rifampin. All K. pneumoniae strains tested positive for K. pneumoniae carbapenemase (KPC) genes by real-time PCR and had elevated polymyxin B MIC values ranging from 16 to 128 g/ml. Synergy was observed with the combination of polymyxin B and rifampin as well as with polymyxin B and doxycycline, resulting in at least a 4-fold decrease in the polymyxin B MIC. For both combinations, this effect occurred at physiologically achievable concentrations. Less pronounced synergy was noted with tigecycline and polymyxin B. No synergy was observed at physiologic concentrations with the other antimicrobials studied. These results suggest that rifampin, doxycycline, and tigecycline may be useful additions to polymyxin B in the treatment of infections caused by highly resistant carbapenemaseproducing K. pneumoniae. Further studies are warranted to determine if these in vitro findings translate into clinical efficacy.

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“…Numerous studies have been performed in recent years using a pharmacodynamic model or standard time-kill studies of the effect of polymyxin B or colistin against strains of P. aeruginosa (19,59,67,93,107,166), A. baumannii (60,88,106,136,160,170), and K. pneumoniae (20). Nearly all studies demonstrated that the polymyxins produce concentration-dependent killing, with an initial kill followed by regrowth.…”

Section: Bactericidal Activity and Synergy Studiesmentioning

confidence: 99%

Polymyxins Revisited

et al. 2008

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SUMMARY The global emergence of multidrug-resistant gram-negative bacilli has spurred a renewed interest in polymyxins. Once discarded due to concerns regarding nephrotoxicity and neurotoxicity, polymyxins now hold an important role in the antibiotic armamentarium. However, more reliable information is needed to determine the optimal dosing of these agents. Also, unanswered questions regarding in vitro testing remain, including questions regarding the reliability of automated systems and the establishment of appropriate breakpoints for defining susceptibility. Most contemporary clinical studies examining the use of these agents have involved patients with infections due to multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii strains. It has been reassuring that polymyxin therapy for resistant bacteria has resulted in clinical responses and toxicity rates similar to those for carbapenem therapy for susceptible isolates. While most surveillance studies demonstrated high rates of susceptibility, several reports noted the emergence of polymyxin-resistant nosocomial pathogens. Polymyxins have assumed an important antibiotic niche for therapy for hospital-acquired infections; further studies defining the optimal use of these agents will likely extend the duration of their clinical usefulness.

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In vitro effect of minocycline and colistin combinations on imipenem-resistant Acinetobacter baumannii clinical isolates

Abstract: The combination of colistin and minocycline was found to be bactericidal and synergistic against A. baumannii by time-kill methods. There was no agreement between time-kill and Etest methods for synergy testing.

Cited by 77 publications

References 11 publications

In vitro antimicrobials activity against endemic Acinetobacter baumannii multiresistant clones

In vitro antimicrobials activity against endemic Acinetobacter baumannii multiresistant clones

In Vitro Evaluation of Antibiotic Synergy for Polymyxin B-Resistant Carbapenemase-Producing Klebsiella pneumoniae

Polymyxins Revisited

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