Evaluation of the MicroScan Colistin Well and Gradient Diffusion Strips for Colistin Susceptibility Testing in
            <i>Enterobacteriaceae</i>

Lutgring, Joseph D.; Kim, Anny; Campbell, Davina; Karlsson, Maria; Brown, Allison C; Burd, Eileen M.

doi:10.1128/jcm.01866-18

Cited by 17 publications

(17 citation statements)

References 37 publications

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“…MicroScan Colistin Well is a newly developed kit for detection of colistin resistance in Gram-negative bacteria [19] The principle of Rapid ResaPolymyxin Acinetobacter/ Pseudomonas NP test is based on the visual detection of the reduction of the resazurin reagent, a viability colorant that is observed by color change (blue to purple or pink). Interestingly, in the current study, no significant color changes were observed in colistin-resistant P. aeruginosa after the addition of the resazurin reagent for 1 h. After prolonging the observation time for another 1 h, the color changed from blue to purple.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

et al. 2020

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Background: Colistin resistance is considered a serious problem due to a lack of alternative antibiotics. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test is a resazurin reduction-based technique that relies on the visual detection of bacterial growth in the presence of a defined concentration of colistin. The aim of this study was to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in the detection of colistin susceptibility in common clinical Gram-negative bacteria. Results: A total of 253 clinical isolates from a teaching hospital, including Acinetobacter baumanii (n = 58, 8 colistinresistant), Pseudomonas aeruginosa (n = 61, 11 colistin-resistant), Klebsiella pneumoniae (n = 70, 20 colistin-resistant) and Escherichia coli (n = 64, 14 colistin-resistant) were tested in this study. The sensitivity and specificity of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test compared to Broth microdilution method was 100 and 99%, respectively. Conclusions: Our results suggest that Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test could be used as an accurate detection method for colistin resistance.

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Section: Discussionmentioning

confidence: 99%

Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

et al. 2020

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“…Gradient diffusion is generally regarded as an inaccurate method for colistin susceptibility testing. However, historical data have been highly variable, ranging from excellent agreement for Enterobacterales (16)(17)(18) to either moderate (9,(19)(20)(21) or high (2,8,11,12,22,23) rates of errors, particularly VMEs. This variability is likely attributable to multiple factors, in particular the diversity of isolates evaluated in each study, as represented by MIC distributions, species and strain types, and mechanisms of resistance, including heteroresistance.…”

Section: Discussionmentioning

confidence: 99%

“…High rates of very major errors (VMEs) are a major concern for disk diffusion and gradient agar diffusion tests, and these methods pose a significant risk of failing to detect resistant isolates (11,12). This is particularly disappointing for gradient agar diffusion, as gradient strips are widely available, simple to set up and interpret, and in contrast to disk diffusion, also provide MICs.…”

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confidence: 99%

Evaluation of Calcium-Enhanced Media for Colistin Susceptibility Testing by Gradient Agar Diffusion and Broth Microdilution

et al. 2020

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Despite the increasing reliance on polymyxin antibiotics (polymyxin B and colistin) for treatment of multidrug-resistant Gram-negative infections, many clinical laboratories are unable to perform susceptibility testing due to the lack of accurate and reliable methods. Although gradient agar diffusion is commonly performed for other antimicrobials, its use for polymyxins is discouraged due to poor performance characteristics. Performing gradient agar diffusion with calcium enhancement of susceptibility testing media has been shown to improve the identification of polymyxin-resistant isolates with plasmid-mediated resistance (mcr-1). We therefore sought to evaluate the broad clinical applicability of this approach for colistin susceptibility testing by assessing a large and diverse collection of resistant and susceptible patient isolates collected from multiple U.S. medical centers. Among 217 isolates, the overall categorical and essential agreement for calcium-enhanced gradient agar diffusion were 73.7% and 65.5%, respectively, compared to the results for reference broth microdilution. Performance varied significantly by organism group, with agreement being highest for Enterobacterales and lowest for Pseudomonas aeruginosa. Nevertheless, even for Enterobacterales, there was a high rate of very major errors (9.2%). Performance was similarly poor for calcium-enhanced broth microdilution. While calcium enhancement did allow for more accurate categorization of mcr-1-resistant isolates, there were unacceptably high rates of errors for both susceptible and non-mcr-1-resistant isolates, raising serious doubts about the suitability of these calcium-enhanced methods for routine colistin susceptibility testing in clinical laboratories.

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“…Antimicrobial susceptibility testing was performed by MicroScan autoScan-4 system using Microscan dehydrated broth microdilution negative MIC Panel Type 44 (NM44) (Beckman Coulter, Inc. USA) following the manufacturer's guidelines [67]. The following antibiotics were tested in the panels: amikacin, aztreonam, cefepime, ceftazidime, cipro oxacin, doripenem, gentamicin, imipenem, levo oxacin, meropenem, piperacillin/tazobactam, piperacillin and tobramycin.…”

Section: Antimicrobial Susceptibility Testingmentioning

confidence: 99%

Antibiotic resistant gene of Pseudomonas aeruginosa from non-clinical environment: public health implications in Mthatha, Eastern Cape Province, South Africa

Hosu¹,

Vasaikar²,

Okuthe³

et al. 2020

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Background Pseudomonas aeruginosa (P. aeruginosa) are Gram-negative bacilli that are ubiquitous in nature particularly plentiful in soils and in aquatic milieu because they thrive well in humid or wet environments. It has extensive metabolic versatility, ability to thrive well and colonize diverse ecological habitats such as soil, rhizosphere, wastewaters that, enhances its potential threat to public health. Abattoirs, aquatic ecosystem including generated wastewaters are latent sources of pathogenic bacteria, serve as reservoirs and contribute to the spread of antibiotic resistant genes. Several studies have focused on clinical environment while scarce data exist from non-clinical environments, which sometimes are hotspots of antibiotic resistance. Thus, the present investigation aimed to identify antibiotic resistant gene of P. aeruginosa from non-clinical sources in Mthatha, Eastern Cape and evaluate its public health implications. Results Fifty-five (55) Pseudomonas species and other organisms recovered from effluent and surface water samples included P. aeruginosa (65.4%), P. fluorescens (27.3%), Burkholderia gladioli (5.5%) and Burkholderia cepacia (1.8%). The P. aeruginosa isolates showed high resistance to aztreonam (86.1%), ceftazidime (63.9%), piperacillin (58.3%) and cefepime (55.6%); with moderate resistance displayed to imipenem (50%), piperacillin/tazobactam (47.2%), meropenem (41.7%) and levofloxacin (30.6%). Twenty out of thirty-six (36) P. aeruginosa displayed multidrug resistance profiles and were classified as multidrug resistant (MDR) (55.6%). Most of the bacterial isolates exhibited a high Multiple Antibiotic Resistance (MAR) Index of > 0.2 ranging from 0.08–0.69 with a mean MAR Index of 0.38. PCR analysis of fifteen (15) P. aeruginosa isolates detected 14 (93.3%) harbored blaSHV, 6 (40%) harbored blaTEM with the least occurring ESBL as blaCTX−M at 3 (20%). Conclusions Results of the current study indicating resistance of environmental P. aeruginosa isolates to front-line clinically relevant antipseudomonal drugs is concerning and poses risk to the environment and receiving water bodies. Given the public health relevance, the results of this study highlight the importance and urgent need of monitoring multidrug-resistant pathogens in effluent environments. These non-clinical environments are potential reservoirs of resistance genes that would further serve as avenues for the dissemination of multidrug resistant bacteria in the community.

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Evaluation of the MicroScan Colistin Well and Gradient Diffusion Strips for Colistin Susceptibility Testing in Enterobacteriaceae

Cited by 17 publications

References 37 publications

Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

Evaluation of Calcium-Enhanced Media for Colistin Susceptibility Testing by Gradient Agar Diffusion and Broth Microdilution

Antibiotic resistant gene of Pseudomonas aeruginosa from non-clinical environment: public health implications in Mthatha, Eastern Cape Province, South Africa

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