Phenotypic Detection of Plasmid-Mediated Colistin Resistance in
            <i>Enterobacteriaceae</i>

Escalante, Edgar Gonzales; Yauri-Condor, Katherine; Conza, José Alejandro Di; Gutkind, Gabriel

doi:10.1128/jcm.01555-19

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…strains. Besides that, it can be easily implemented, and it has a low cost in a clinical laboratory setup [ 21 ].…”

Section: Resultsmentioning

confidence: 99%

“…All samples were tested in duplicate. Reading was performed after 20 h according to the following interpretation: positive growth (resistant to polymyxin B) when more than 1 colony was observed; negative growth (susceptible to polymyxin B) when there were no bacterial colonies [ 21 ]. The procedures were performed in duplicate and in two independent experiments.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synergistic Effect between Usnic Acid and Polymyxin B against Resistant Clinical Isolates of Pseudomonas aeruginosa

Júnior

Silva

et al. 2020

Evidence-Based Complementary and Alternative Medicine

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The present study aimed to characterize the susceptibility profile of Pseudomonas aeruginosa and Acinetobacter spp. clinical isolates to polymyxin B in a public hospital in Recife-PE, Brazil, between the years of 2018 and 2019, as well as to search for the presence of the mcr-1 gene and evaluate the interaction between polymyxin B and usnic acid against these isolates. The strains were identified using the BD Phoenix™ automated system and the agar-spot test was used to determine the susceptibility profile to polymyxin B. The minimum inhibitory concentrations (MICs) of usnic acid and polymyxin B were determined through the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI). Subsequently, Polymerase Chain Reaction (PCR) was performed to detect the mcr-1 gene in the isolates. The interaction between usnic acid and polymyxin B was evaluated by the Checkerboard assay. Among 34 isolates of P. aeruginosa, 26.5% (9/34) were positive for the polymyxin B agar-spot test, and 11.8% (4/34) presented an intermediate susceptibility (MIC = 4 μg/mL), while 14.7% (5/34) presented antimicrobial resistance with MIC values ranging from 8 to 32 μg/mL. Among 38 isolates of Acinetobacter spp., 13.2% (5/38) were positive for the polymyxin B agar-spot test and all of them were resistant to polymyxin B with a MIC value > 32 μg/mL. The mcr-1 gene was not detected in the clinical isolates. Regarding usnic acid, it presented a moderate antibacterial activity against two P. aeruginosa isolates (MIC = 250 μg/mL) and no activity was detected against the others. A synergistic effect between usnic acid and polymyxin B was observed against three clinical isolates of P. aeruginosa which were resistant to polymyxin B (FICI ≤ 0.5). Therefore, it was possible to observe that usnic acid is a promising candidate to be used in combination with polymyxin B against infections caused by resistant P. aeruginosa.

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“…strains. Besides that, it can be easily implemented, and it has a low cost in a clinical laboratory setup [ 21 ].…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Synergistic Effect between Usnic Acid and Polymyxin B against Resistant Clinical Isolates of Pseudomonas aeruginosa

Júnior

Silva

et al. 2020

Evidence-Based Complementary and Alternative Medicine

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“…The CLSI screening test showed no ME and only 0.5% of VME, exclusively among Enterobacterales , values comparable to those obtained with the COL-AS proposed here. An adaptation of the COL-AS proposed here was recently used for the specific detection of mcr producers, by adding an extra plate of colistin supplemented with EDTA, a well-known mcr inhibitor (39). Other agar-based colistin methods on the market were successfully utilized for screening purposes from clinical samples (40), showing the versatility of techniques based on agar dilution.…”

Section: Discussionmentioning

confidence: 99%

Simple phenotypic tests to improve accuracy in screening chromosomal and plasmid-mediated colistin resistance in gram-negative bacilli

Pasterán¹,

Danze²,

Menocal³

et al. 2020

Preprint

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ABSTRACTCLSI and EUCAST recommends that only broth microdilution (BMD) should be used for routine colistin susceptibility testing, however, it could be difficult to perform in resource-poor settings. The purpose of this study was to evaluate the accuracy of an agar spot test (COL-AS) and a colistin drop test (COL-DT) as compared to BMD. COL-AS and COL-DT were challenged with a collection of 271 Gram-negative bacilli clinical isolates: 195 Enterobacterales (including 63 mcr-1 positive strains), 37 Acinetobacter spp. and 39 P. aeruginosa. For COL-AS, 3.0µg/ml (final concentration) of colistin was added to a Mueller-Hinton agar plate and subsequently swabbed with a 0.5 McFarland suspension of tested strain within 1cm2 spot. For COL-DT, 10µl of a 16µg/ml colistin solution was dripped on the surface of a Mueller-Hinton agar plate, previously inoculated with a lawn of tested strain (0.5 McFarland). Colistin solution was made either, by dissolving powder or by disk elution in CA-MHB. Overall, 141/271 (52%) isolates were categorized as colistin resistant by reference BMD. COL-AS yielded a categorical agreement (CA) of 95.5% compared to BMD, with 0.7% very major errors and 3.8% major errors. COL-DR yielded a CA of 96.2% compared to BMD, with 0.7% and 0% very major errors and 3.1% and 3.8% major errors, for colistin powder and disk elution solutions, respectively. Most major errors occurred for mcr-1 producing strains with MICs that fluctuated from 2 to 4 μg/ml. In conclusion, we developed and validated methods suited to the systematic screening of resistance to colistin in gram negative bacilli.Clinical relevancecolistin continues to be one of the last-line therapeutic options to treat carbapenemase-producing gram negative bacilli. The BMD reference methodology, the only one accepted by current standards for evaluating colistin sensitivity, is difficult to implement in laboratories from low-resource countries. In this work, we propose two simple methodologies to screen for colistin resistance, with a performance equivalent to the reference method in detecting resistance to colistin, both of plasmid (mcr) and chromosomal nature. Furthermore, the methods validated here allowed a better identification of those producers of mcr producer with borderline MICs. These screening tests can be routinely performed in addition to the tests currently in use. showed long stability during storage and some of them do not require colistin powder as the source of antibiotic, an important limitation in low-resource countries.

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“…Escalante and collaborators used a modification of the Agar Spot methodology to make a phenotypic identification of the mcr gene with EDTA (1 mM). The study presented 96.7% sensitivity and 83.3% specificity, demonstrating the efficiency of the method in differentiating MCR-producing colistin-resistant enterobacteria from those with chromosomal resistance mechanisms [ 54 ].…”

Section: Phenotypic Methodsmentioning

confidence: 99%

Challenges in the Detection of Polymyxin Resistance: From Today to the Future

Rubens,

Arruda,

Almeida

et al. 2024

Microorganisms

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Antimicrobial resistance is known to be one of the greatest global threats to human health, and is one of the main causes of death worldwide. In this scenario, polymyxins are last-resort antibiotics to treat infections caused by multidrug-resistant bacteria. Currently, the reference test to evaluate the susceptibility of isolates to polymyxins is the broth microdilution method; however, this technique has numerous complications and challenges for use in laboratory routines. Several phenotypic methods have been reported as being promising for implementation in routine diagnostics, including the BMD commercial test, rapid polymyxin NP test, polymyxin elution test, culture medium with polymyxins, and the Polymyxin Drop Test, which require materials for use in routines and must be easy to perform. Furthermore, Sensititre®, molecular tests, MALDI-TOF MS, and Raman spectroscopy present reliable results, but the equipment is not found in most microbiology laboratories. In this context, this review discusses the main laboratory methodologies that allow the detection of resistance to polymyxins, elucidating the challenges and perspectives.

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Phenotypic Detection of Plasmid-Mediated Colistin Resistance in Enterobacteriaceae

Cited by 7 publications

References 25 publications

Synergistic Effect between Usnic Acid and Polymyxin B against Resistant Clinical Isolates of Pseudomonas aeruginosa

Synergistic Effect between Usnic Acid and Polymyxin B against Resistant Clinical Isolates of Pseudomonas aeruginosa

Simple phenotypic tests to improve accuracy in screening chromosomal and plasmid-mediated colistin resistance in gram-negative bacilli

Challenges in the Detection of Polymyxin Resistance: From Today to the Future

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