Comparative assessment of antimicrobial susceptibility testing for tigecycline and colistin against Acinetobacter baumannii clinical isolates, including multidrug-resistant isolates

Piewngam, Pipat; Kiratisin, Pattarachai

doi:10.1016/j.ijantimicag.2014.06.014

Cited by 35 publications

(24 citation statements)

References 20 publications

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“…Moreover, 7.1% of the tested isolates were characterized by MIC values lower than or equal to ECOFF values and for 90% of isolates the the MIC value was ≥ 2 mg L -1 (the MIC 50 and MIC 90 values were 3 and 6 mg L -1 , respectively). Similar results indicating the presence of Acinetobacter strains with high MIC values were obtained by Piewngam and Kiratisin in a study of 290 isolates including MDR (multidrug resistant) strains from different clinical specimens from patients hospitalized at the University Hospital in Bangkok (MIC range, MIC 50, and MIC 90 values were 0.5-8.0 mg L -1 , 2.0 mg L -1 , and 4.0 mg L -1 , respectively) [11]. Navon-Venezia et al [15] reported high tigecycline [17].…”

Section: Discussionsupporting

confidence: 83%

“…They found that Etest produced susceptibility results similar to those obtained with broth microdilution, while MIC values obtained by VITEK2 were higher than in the case of other tests. Moreover, a good concordance of the disk diffusion, Etest and BMD methods was found by Piewngam and Kiratisin [11]. On the other hand, there are some publications which present the opposite conclusions.…”

Section: Discussionmentioning

confidence: 79%

“…EUCAST recognizes that all strains with MIC ≤ 1 mg L -1 do not have mutations that can lead to the acquisition of resistance (apart from a natural and known resistance characteristic for a given species -determined by the EUCAST ECOFF value is as 1 mg L -1 ). However, Piewngam and Kiratisin [11] suggest that the MIC breakpoint should be modified to S ≤ 0.5 and R > 2 mg L -1 . It has been pointed out that the determination of the antimicrobial activity of tigecycline might vary with the use of different methods, while the disk diffusion method is not reliable as regards the determination of susceptibility to tigecycline and gives lower susceptibility rates as compared to Etest or the broth microdilution method (BMD) [10,12].…”

Section: Discussionmentioning

confidence: 99%

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Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

Talaga

Krzyściak

Bulanda

2016

Anaesthesiol Intensive Ther

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Background: Infections caused by Acinetobacter baumannii are difficult to cure due to the acquisition of resistance by these bacteria and lead to an increase in the general costs of hospitalization. The aim of this study was to determine tigecycline susceptibility of Acinetobacter baumannii strains isolated from intensive care unit and non-intensive care unit patients with skin and soft tissue infections. Methods: MICs were tested by Etest among 70 Acinetobacter baumannii isolates. Results: The MIC range was from 0.5 to 8.0 mg L -1 . For ESBL-producing Acinetobacter baumannii, as well as for strains without carbapenemases, the highest MIC to tigecycline value was 8.0 mg L -1 . For AmpC-producing Acinetobacter baumannii, the highest MIC to tigecycline value was 6.0 mg L -1 and, for MBL-producing strains, 2.0 mg L -1 . Conclusions:The majority of Acinetobacter baumannii strains isolated from ICU and non-ICU patients demonstrated high values of MIC range, MIC 50 and MIC 90 to tigecycline.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

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Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

Talaga

Krzyściak

Bulanda

2016

Anaesthesiol Intensive Ther

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“…As for tigecycline (TGC) breakpoints suggested by Piewngam et al were used in disc diffusion testing where a zone diameter of ≥17 mm was considered sensitive, while a diameter of ≤12 mm was considered resistant [15].…”

Section: Disc Diffusion Testmentioning

confidence: 99%

<i>In Vitro</i> Activity of Colistin and Vancomycin or Azithromycin Combinations on Extensively Drug Resistant <i>Acinetobacter baumannii</i> Clinical Isolates

Okasha¹,

Meheissen²

2017

AiM

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Background: Extensively drug resistant Acinetobacter baumannii (XDR-AB) presents an increasing challenge to health care in Egypt as they are among the most common bacteria isolated in hospital setting. Treatment of such infections usually involves the use of antimicrobial agents in combination. Various combinations have been proposed, with colistin serving as the backbone in many of them even for colistin resistant isolates. Aim: The study was conducted in order to test the in vitro combined effects of colistin and vancomycin or azithromycin against (XDR-AB) causing infections at Alexandria Main University Hospital in Egypt, in an attempt to detect the possibility of a beneficial combination therapy. Material/Methods: Thirty XDR-AB clinical isolates were included in the study. Antibiotic susceptibility testing was performed using automated Vitek 2 compact system and disc diffusion method. Colistin antibiotic disc diffusion test was compared with broth microdilution method. Organisms were also tested against colistin and vancomycin or azithromycin in combination using checkerboard synergy test and FICI (Fractional Inhibitory Concentration Index) was calculated. Synergy was defined as a FICI of ≤0.5. Results: On comparing the two methods used to detect susceptibility to colistin to broth microdilution for MIC (minimum inhibitory concentration) determination, as a reference method, the Vitek showed 100% categorical agreement (CA), on the other hand, the disc diffusion showed CA of 93% with very major errors. Synergy was detected for all isolates (100%) when combining colistin with vancomycin (FICI mean = 0.08). As for azithromycin, 21 strains had FICI range from 0.7 to 1.001, denoting indifference; the remaining 9 strains showed synergy with FICI range from 0.06 to 0.241. The mean colistin/azithromycin FICI was 0.71 for the 30 isolates. Conclusion: These findings suggest that regimens containing vancomycin may confer therapeutic benefit for infection due to XDR-AB; however, other methods (time-kill assay) should be used to confirm such synergy. Furthermore, the optimal combination treatment for serious XDR-AB infection should be addressed in a prospective clinical trial.

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“…Manual BMD, however, is laborious and not performed in many routine clinical microbiology laboratories, which often rely on diffusion or automated systems for susceptibility testing. Moreover, and somewhat paradoxically in view of the drugs' poor diffusion in agar, diffusion methods (both disk and gradient strips) have been found to have unacceptably high levels of false susceptibility (or very major errors [VMEs]) in multiple studies (12,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28) (Table 1). Both the CLSI and EUCAST have now advised against diffusion methods for the polymyxins, removing disk diffusion interpretive criteria for them from their guidance documents (9,15,22).…”

mentioning

confidence: 99%

Susceptibility Testing for the Polymyxins: Two Steps Back, Three Steps Forward?

Vasoo

2017

J Clin Microbiol

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Optimizing and standardizing susceptibility testing for the polymyxins have become pressing issues, given the rise in multidrug-resistant Gram-negative bacilli. Recently, both the CLSI and EUCAST have recommended broth microdilution (BMD) (without polysorbate) as the reference method for polymyxin susceptibility testing. In this issue, K. L. Chew et al. (J Clin Microbiol 55:2609 -2616, https://doi .org/10.1128/JCM.00268-17) compare the performances of three commercial BMD panels and the Etest to the reference, BMD, for polymyxin B and colistin, using 76 Enterobacteriaceae isolates (21 of which were mcr-1 positive). Although none of the commercial BMD panels strictly met FDA performance standards in this evaluation, possibly because of the small number isolates tested, the Sensititre panel achieved Ͼ90% categorical agreement for both polymyxin compounds. These results also reaffirm CLSI and EUCAST guidance that gradient diffusion testing, which had unacceptable error rates, should be abandoned. In a simulated analysis with lowered breakpoints (susceptible, Յ1 mg/liter; intermediate, 2 mg/liter; resistant, Ն4 mg/liter), error rates and agreement were improved across the various methods and the rate of detection of mcr-1-positive isolates improved. These observations, taken together with recent pharmacokinetic data on optimizing target attainment for the polymyxins, suggest that more-stringent (lower) breakpoints may be reasonable, although such an approach may be limited by the inherent reliability of current testing methodologies and a lack of robust clinical correlative data, which are sorely needed. S usceptibility testing for the polymyxins has been beleaguered over the years. The polymyxins were first isolated from Paenibacillus polymyxa in 1947 by two independent American groups (1, 2), and there has been a therapeutic renaissance in the use of both polymyxin B and colistin (polymyxin E) over the last decade, given the rise of multidrug-resistant (MDR) Gram-negative bacilli, such as MDR Acinetobacter and Pseudomonas and carbapenemase-producing Enterobacteriaceae.Despite susceptibility testing being available for a long time, clarity has been lacking for appropriate methods of testing and optimal dosing for the polymyxins. Polymyxins are cationic polypeptides comprised of a heptapeptide ring, an exocyclic chain, and a fatty acid tail with positively charged residues which interact with and disrupt the Gram-negative lipopolysaccharide membrane; polymyxin B and colistin differ by only one amino acid in the heptapeptide ring (3, 4). Several reasons have accounted for difficulties with susceptibility testing for the polymyxins, including their cationic nature, their poor diffusion in agar due to their large molecular size, concerns over drug powder composition, and their heteroresistance. Further, the complex pharmacokinetics (PK) and pharmacodynamics (PD) of these compounds and the paucity of data correlating MIC data, drug concentration, and clinical outcomes have made setting clinical breakpoints chal...

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Comparative assessment of antimicrobial susceptibility testing for tigecycline and colistin against Acinetobacter baumannii clinical isolates, including multidrug-resistant isolates

Cited by 35 publications

References 20 publications

Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

<i>In Vitro</i> Activity of Colistin and Vancomycin or Azithromycin Combinations on Extensively Drug Resistant <i>Acinetobacter baumannii</i> Clinical Isolates

Susceptibility Testing for the Polymyxins: Two Steps Back, Three Steps Forward?

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Comparative assessment of antimicrobial susceptibility testing for tigecycline and colistin against Acinetobacter baumannii clinical isolates, including multidrug-resistant isolates

Cited by 35 publications

References 20 publications

Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

Susceptibility to tigecycline of Acinetobacter baumannii strains isolated from intensive care unit patients

&lt;i&gt;In Vitro&lt;/i&gt; Activity of Colistin and Vancomycin or Azithromycin Combinations on Extensively Drug Resistant &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; Clinical Isolates

Susceptibility Testing for the Polymyxins: Two Steps Back, Three Steps Forward?

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<i>In Vitro</i> Activity of Colistin and Vancomycin or Azithromycin Combinations on Extensively Drug Resistant <i>Acinetobacter baumannii</i> Clinical Isolates