1
|
Rubens RS, Arruda IDSA, Almeida RM, Nóbrega YKDM, Carneiro MDS, Dalmolin TV. Challenges in the Detection of Polymyxin Resistance: From Today to the Future. Microorganisms 2024; 12:101. [PMID: 38257928 PMCID: PMC10818861 DOI: 10.3390/microorganisms12010101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/12/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
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.
Collapse
Affiliation(s)
- Rebeca Siqueira Rubens
- Laboratório de Microbiologia e Imunologia Clínica (LabMIC), Departamento de Farmácia, Faculdade de Ciências da Saúde, Universidade de Brasília (UnB), Brasília 70910-900, DF, Brazil; (R.S.R.); (I.d.S.A.A.); (R.M.A.); (Y.K.d.M.N.)
| | - Isabel de Souza Andrade Arruda
- Laboratório de Microbiologia e Imunologia Clínica (LabMIC), Departamento de Farmácia, Faculdade de Ciências da Saúde, Universidade de Brasília (UnB), Brasília 70910-900, DF, Brazil; (R.S.R.); (I.d.S.A.A.); (R.M.A.); (Y.K.d.M.N.)
| | - Rosane Mansan Almeida
- Laboratório de Microbiologia e Imunologia Clínica (LabMIC), Departamento de Farmácia, Faculdade de Ciências da Saúde, Universidade de Brasília (UnB), Brasília 70910-900, DF, Brazil; (R.S.R.); (I.d.S.A.A.); (R.M.A.); (Y.K.d.M.N.)
| | - Yanna Karla de Medeiros Nóbrega
- Laboratório de Microbiologia e Imunologia Clínica (LabMIC), Departamento de Farmácia, Faculdade de Ciências da Saúde, Universidade de Brasília (UnB), Brasília 70910-900, DF, Brazil; (R.S.R.); (I.d.S.A.A.); (R.M.A.); (Y.K.d.M.N.)
| | | | - Tanise Vendruscolo Dalmolin
- Laboratório de Microbiologia e Imunologia Clínica (LabMIC), Departamento de Farmácia, Faculdade de Ciências da Saúde, Universidade de Brasília (UnB), Brasília 70910-900, DF, Brazil; (R.S.R.); (I.d.S.A.A.); (R.M.A.); (Y.K.d.M.N.)
| |
Collapse
|
2
|
Gogry FA, Siddiqui MT, Sultan I, Haq QMR. Current Update on Intrinsic and Acquired Colistin Resistance Mechanisms in Bacteria. Front Med (Lausanne) 2021; 8:677720. [PMID: 34476235 PMCID: PMC8406936 DOI: 10.3389/fmed.2021.677720] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 07/09/2021] [Indexed: 01/07/2023] Open
Abstract
Colistin regained global interest as a consequence of the rising prevalence of multidrug-resistant Gram-negative Enterobacteriaceae. In parallel, colistin-resistant bacteria emerged in response to the unregulated use of this antibiotic. However, some Gram-negative species are intrinsically resistant to colistin activity, such as Neisseria meningitides, Burkholderia species, and Proteus mirabilis. Most identified colistin resistance usually involves modulation of lipid A that decreases or removes early charge-based interaction with colistin through up-regulation of multistep capsular polysaccharide expression. The membrane modifications occur by the addition of cationic phosphoethanolamine (pEtN) or 4-amino-l-arabinose on lipid A that results in decrease in the negative charge on the bacterial surface. Therefore, electrostatic interaction between polycationic colistin and lipopolysaccharide (LPS) is halted. It has been reported that these modifications on the bacterial surface occur due to overexpression of chromosomally mediated two-component system genes (PmrAB and PhoPQ) and mutation in lipid A biosynthesis genes that result in loss of the ability to produce lipid A and consequently LPS chain, thereafter recently identified variants of plasmid-borne genes (mcr-1 to mcr-10). It was hypothesized that mcr genes derived from intrinsically resistant environmental bacteria that carried chromosomal pmrC gene, a part of the pmrCAB operon, code three proteins viz. pEtN response regulator PmrA, sensor kinase protein PmrAB, and phosphotransferase PmrC. These plasmid-borne mcr genes become a serious concern as they assist in the dissemination of colistin resistance to other pathogenic bacteria. This review presents the progress of multiple strategies of colistin resistance mechanisms in bacteria, mainly focusing on surface changes of the outer membrane LPS structure and other resistance genetic determinants. New handier and versatile methods have been discussed for rapid detection of colistin resistance determinants and the latest approaches to revert colistin resistance that include the use of new drugs, drug combinations and inhibitors. Indeed, more investigations are required to identify the exact role of different colistin resistance determinants that will aid in developing new less toxic and potent drugs to treat bacterial infections. Therefore, colistin resistance should be considered a severe medical issue requiring multisectoral research with proper surveillance and suitable monitoring systems to report the dissemination rate of these resistant genes.
Collapse
Affiliation(s)
| | | | - Insha Sultan
- Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | | |
Collapse
|
3
|
Leshaba TMS, Mbelle NM, Osei Sekyere J. Current and emerging polymyxin resistance diagnostics: A systematic review of established and novel detection methods. J Appl Microbiol 2021; 132:8-30. [PMID: 34152057 DOI: 10.1111/jam.15184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 05/09/2021] [Accepted: 06/16/2021] [Indexed: 01/19/2023]
Abstract
The emergence of polymyxin resistance, due to transferable mcr genes, threatens public and animal health as there are limited therapeutic options. As polymyxin is one of the last-line antibiotics, there is a need to contain the spread of its resistance to conserve its efficacy. Herein, we describe current and emerging polymyxin resistance diagnostics to inform faster clinical diagnostic choices. A literature search in diverse databases for studies published between 2016 and 2020 was performed. English articles evaluating colistin resistance methods/diagnostics were included. Screening resulted in the inclusion of 93 journal articles. Current colistin resistance diagnostics are either phenotypic or molecular. Broth microdilution is currently the only gold standard for determining colistin MICs (minimum inhibitory concentration). Phenotypic methods comprise of agar-based methods such as CHROMagar™ Col-APSE, SuperPolymyxin, ChromID® Colistin R, LBJMR and LB medium; manual MIC-determiners viz., UMIC, MICRONAUT MIC-Strip and ComASP Colistin; automated antimicrobial susceptibility testing systems such as BD Phoenix, MICRONAUT-S, MicroScan, Sensititre and Vitek 2; MCR-detectors such as lateral flow immunoassay (LFI) and chelator-based assays including EDTA- and DPA-based tests, that is, combined disk test, modified colistin broth-disk elution (CBDE), Colispot, and Colistin MAC test as well as biochemical colorimetric tests, that is, Rapid Polymyxin NP test and Rapid ResaPolymyxin NP test. Molecular methods only characterize mobile colistin resistance; they include PCR, LAMP and whole-genome sequencing. Due to the faster turnaround time (≤3 h), improved sensitivity (84%-100%) and specificity (93.3%-100%) of the Rapid ResaPolymyxin NP test and Fastinov® , we recommend this test for initial screening of colistin-resistant isolates. This can be followed by CBDE with EDTA or the LFI as they both have 100% sensitivity and a specificity of ≥94.3% for the rapid screening of mcr genes. However, molecular assays such as LAMP and PCR may be considered in well-equipped clinical laboratories.
Collapse
Affiliation(s)
- Tumisho Mmatumelo Seipei Leshaba
- Department of Medical Microbiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Nontombi Marylucy Mbelle
- Department of Medical Microbiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - John Osei Sekyere
- Department of Medical Microbiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| |
Collapse
|
4
|
Raro OHF, Collar GS, da Silva RMC, Vezzaro P, Mott MP, da Cunha GR, Riche CVW, Dias C, Caierão J. Performance of polymyxin B agar-based tests among carbapenem-resistant Enterobacterales. Lett Appl Microbiol 2021; 72:767-773. [PMID: 33629416 DOI: 10.1111/lam.13467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 01/10/2023]
Abstract
Therapeutic options for infections caused by Carbapenem-resistant Enterobacterales (CRE) are restricted and include polymyxins-centred schemes. Evaluation of in vitro susceptibility is difficult and time consuming. Agar-based methodologies are an alternative to broth microdilution (BMD) and we aimed to evaluate the accuracy of those methods among Enterobacterales. A total of 137 non-duplicated CRE were subjected to polymyxin B BMD, agar screening test (Mueller Hinton plates containing 3 µg ml-1 of polymyxin B) and agar dilution (antibiotic serially diluted 0·25-64 µg ml-1 ). CRE of 42·3% were resistant to polymyxin B (MICs range: 0·25->64 µg ml-1 ) and 16·8% presented borderline MICs. Sensitivity, specificity, PPV and NPV were 86·2, 98·7, 98 and 90·7% for screening test and 86·2, 97·5, 96·1 and 90·6% for agar dilution. ME was 0·73 and 1·5% for screening and agar dilution respectively; VME was 5·8% for both techniques. In general, agar-based methods had a good performance. As far as we know, this is the first study to propose an agar screening test using polymyxin B instead of colistin.
Collapse
Affiliation(s)
- O H F Raro
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - G S Collar
- Department of Analysis, Faculty of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - R M C da Silva
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - P Vezzaro
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - M P Mott
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil.,Department of Microbiology, Ernesto Dornelles Hospital, Porto Alegre, Brazil
| | - G R da Cunha
- Department of Microbiology, Ernesto Dornelles Hospital, Porto Alegre, Brazil
| | - C V W Riche
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil.,Department of Microbiology, Ernesto Dornelles Hospital, Porto Alegre, Brazil
| | - C Dias
- Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - J Caierão
- Department of Analysis, Faculty of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Post-Graduation Program of Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| |
Collapse
|
5
|
Fournier C, Poirel L, Nordmann P. Implementation and evaluation of methods for the optimal detection of carbapenem-resistant and colistin-resistant Pseudomonas aeruginosa and Acinetobacter baumannii from stools. Diagn Microbiol Infect Dis 2020; 98:115121. [DOI: 10.1016/j.diagmicrobio.2020.115121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/16/2020] [Accepted: 06/20/2020] [Indexed: 12/25/2022]
|
6
|
Optimal detection of extended-spectrum β-lactamase producers, carbapenemase producers, polymyxin-resistant Enterobacterales, and vancomycin-resistant enterococci from stools. Diagn Microbiol Infect Dis 2020; 96:114919. [DOI: 10.1016/j.diagmicrobio.2019.114919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/08/2019] [Accepted: 10/16/2019] [Indexed: 10/25/2022]
|
7
|
Stefaniuk EM, Tyski S. Colistin Resistance in Enterobacterales Strains - A Current View. Pol J Microbiol 2019; 68:417-427. [PMID: 31880886 PMCID: PMC7260631 DOI: 10.33073/pjm-2019-055] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/05/2019] [Accepted: 11/05/2019] [Indexed: 02/07/2023] Open
Abstract
Colistin is a member of cationic polypeptide antibiotics known as polymyxins. It is widely used in animal husbandry, plant cultivation, animal and human medicine and is increasingly used as one of the last available treatment options for patients with severe infections with carbapenem-resistant Gram-negative bacilli. Due to the increased use of colistin in treating infections caused by multidrug-resistant (MDR) bacteria, the resistance to this antibiotic ought to be monitored. Bacterial resistance to colistin may be encoded on transposable genetic elements (e.g. plasmids with the mcr genes). Thus far, nine variants of the mcr gene, mcr-1 – mcr-9, have been identified. Chromosomal resistance to colistin is associated with the modification of lipopolysaccharide (LPS). Various methods, from classical microbiology to molecular biology methods, are used to detect the colistin-resistant bacterial strains and to identify resistance mechanisms. The broth dilution method is recommended for susceptibility testing of bacteria to colistin.
Collapse
Affiliation(s)
- Elżbieta M Stefaniuk
- Department of Antibiotics and Microbiology, National Medicines Institute , Warsaw , Poland
| | - Stefan Tyski
- Department of Antibiotics and Microbiology, National Medicines Institute , Warsaw , Poland ; Department of Pharmaceutical and Microbiology, Medical University of Warsaw , Warsaw , Poland
| |
Collapse
|
8
|
The added value of the selective SuperPolymyxin™ medium in detecting rectal carriage of Gram-negative bacteria with acquired colistin resistance in intensive care unit patients receiving selective digestive decontamination. Eur J Clin Microbiol Infect Dis 2019; 39:265-271. [PMID: 31691864 PMCID: PMC7010615 DOI: 10.1007/s10096-019-03718-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 09/20/2019] [Indexed: 12/02/2022]
Abstract
The objective of this study was to determine the value of using SuperPolymyxin™ selective medium (ELITech Group, Puteaux, France) in addition to conventional non-selective inoculation methods in the detection of acquired colistin resistance in a Dutch intensive care unit (ICU) that routinely uses selective decontamination of the digestive tract (SDD). We performed a cross-sectional study with prospective data collection in a tertiary-care ICU. All consecutive surveillance rectal swabs of ICU-patients receiving SDD were included and cultured in an observer-blinded approach using (1) a conventional culture method using non-selective media and (2) SuperPolymyxin™ selective medium. MIC values for colistin of non-intrinsically colistin-resistant Gram-negative isolates were determined with broth microdilution (BMD) using Sensititre™ and colistin resistance was confirmed using BMD according to EUCAST guidelines. One thousand one hundred five rectal swabs of 428 unique ICU-patients were inoculated using both culture methods, yielding 346 and 84 Gram-negative isolates for BMD testing with the conventional method and SuperPolymyxin™ medium, of which 308 and 80 underwent BMD, respectively. The number of identified rectal carriers of isolates with acquired colistin resistance was 3 (0.7%) for the conventional method, 4 (0.9%) for SuperPolymyxin™, and 5 (1.2%) for both methods combined. The number of isolates with acquired colistin resistance was 4 (1.0%) for the conventional method, 8 (2.1%) for SuperPolymyxin™ and 9 (2.3%) for both methods combined. In a surveillance setting of low prevalence of acquired colistin resistance in patients that receive SDD in a Dutch tertiary-care ICU, SuperPolymyxin™ had a higher diagnostic yield than conventional inoculation methods, but the combination of both had the highest diagnostic yield.
Collapse
|
9
|
Germ J, Cerar Kišek T, Kokošar Ulčar B, Lejko Zupanc T, Mrvič T, Kerin Povšič M, Seme K, Pirs M. Surveillance cultures for detection of rectal and lower respiratory tract carriage of colistin-resistant Gram-negative bacilli in intensive care unit patients: comparison of direct plating and pre-enrichment step. J Med Microbiol 2019; 68:1269-1278. [PMID: 31237536 DOI: 10.1099/jmm.0.001029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose. Increasing consumption of colistin as treatment for infections with multidrug-resistant (MDR) Gram-negative bacilli (GNB) has been accompanied by increasingly frequent reports of colistin-resistant (ColR) MDR GNB. Higher selective pressure creates a favourable environment that can facilitate the spread of ColR isolates. Monitoring of asymptomatic ColR GNB carriage can give us a better understanding of this emerging healthcare problem, particularly in wards with higher polymyxin selective pressure and prevalence of carbapenem-resistant GNB. Our aim was to assess the ColR GNB colonization rate in intensive care unit (ICU) patients and evaluate the performance of two surveillance protocols using a selective medium.Methodology. A prospective study included 739 surveillance samples (rectal swabs and tracheal aspirates) from 330 patients that were screened for ColR GNB carriage using SuperPolymyxin medium. Two approaches were used: direct sample plating and overnight pre-enrichment of samples followed by plating. Colistin resistance was confirmed with broth microdilution. ColR isolates were molecularly screened for plasmid-mediated mcr genes.Results. A total of 44/739 samples (45 ColR GNB isolates) were positive for ColR GNB, which included 31/330 (9.4 %) colonized patients; mcr genes were not detected. The direct plating method only identified 17/45 (37.8 %) isolates correctly, whereas the pre-enrichment protocol identified all 45 ColR GNB.Conclusion. The colonization rate among our ICU patients was 9.4 %. Based on our findings, the pre-enrichment step is necessary for the determination of ColR GNB carriage - even though the time to result takes an additional day, fewer than half of ColR GNB carriers were detected using the direct plating protocol.
Collapse
Affiliation(s)
- Julija Germ
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tjaša Cerar Kišek
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Barbara Kokošar Ulčar
- Department of Infectious Diseases, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Tatjana Lejko Zupanc
- Department of Infectious Diseases, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Tatjana Mrvič
- Department of Infectious Diseases, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Infection Control Unit, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | | | - Katja Seme
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mateja Pirs
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| |
Collapse
|
10
|
Comparison of the Superpolymyxin and ChromID Colistin R Screening Media for the Detection of Colistin-Resistant Enterobacteriaceae from Spiked Rectal Swabs. Antimicrob Agents Chemother 2018; 63:AAC.01618-18. [PMID: 30323032 DOI: 10.1128/aac.01618-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/08/2018] [Indexed: 11/20/2022] Open
Abstract
The dissemination of carbapenemase-producing Enterobacteriaceae (CPE) has led to the increased use of colistin, which has resulted in the emergence of colistin-resistant Enterobacteriaceae worldwide. One of the most threatening scenarios is the dissemination of colistin resistance in CPE, particularly the plasmid-encoded resistance element MCR. Thus, it has now become mandatory to possess reliable media to screen for colistin-resistant Gram-negative bacterial isolates, especially Enterobacteriaceae In this study, we evaluated the performances of the Superpolymyxin medium (ELITechGroup) and the ChromID Colistin R medium (bioMérieux) to screen for colistin-resistant Enterobacteriaceae from spiked rectal swabs. Stool samples were spiked with a total of 94 enterobacterial isolates (Escherichia coli, Klebsiella pneumoniae, Salmonella enterica, Enterobacter cloacae), including 53 colistin-resistant isolates. ESwabs (Copan Diagnostics) were then inoculated with those spiked fecal suspensions, and culture proceeded as recommended by both manufacturers. The sensitivity of detection of colistin-resistant Enterobacteriaceae was 86.8% (95% confidence interval [95% CI] = 74.0% to 94.0%) using both the Superpolymyxin medium and the ChromID Colistin R plates. Surprisingly, the isolates that were not detected were not the same for both media. The specificities were high for both media, at 97.9% (95% CI = 87.3% to 99.9%) for the Superpolymyxin medium and 100% (95% CI = 90.4% to 100%) for the ChromID Colistin R medium. Both commercially available media, ChromID Colistin R and Superpolymyxin, provide useful tools to screen for colistin-resistant Enterobacteriaceae from patient samples (rectal swabs) regardless of the level and mechanism of colistin resistance.
Collapse
|
11
|
Przybysz SM, Correa-Martinez C, Köck R, Becker K, Schaumburg F. SuperPolymyxin™ Medium for the Screening of Colistin-Resistant Gram-Negative Bacteria in Stool Samples. Front Microbiol 2018; 9:2809. [PMID: 30519224 PMCID: PMC6258816 DOI: 10.3389/fmicb.2018.02809] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/31/2018] [Indexed: 11/30/2022] Open
Abstract
Colistin is one of the last resort antimicrobials for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. After the emergence of transferable colistin resistance genes (mcr-1–5), a reliable culture-based screening method to detect colonization with colistin-resistant Gram-negative bacteria (CRGN) is needed. The objective of this study was to test the performance of SuperPolymyxin™ medium to screen for CRGN in stool samples and to compare different methods for the confirmation of colistin resistance (e.g., Etest®, broth microdilution [BMD], and the Rapid Polymyxin™ NP test). Colonization with CRGN was analyzed in a prospective cohort study among travelers. Stool samples (Fecal TranswabTM) taken before, during and after travel were cultured on SuperPolymyxin™ agar. Every phenotypically different colony was subcultured for species identification using MALDI-TOF mass spectrometry. Susceptibility to colistin was tested using Etest® and confirmed by BMD and the Rapid Polymyxin™ NP test. In total, 128 participants provided 1,495 stool samples. After culture on SuperPolymyxin™ medium (37°C, 24–48 h), 1,851 phenotypically different colonies were isolated. Isolates belonging to intrinsically colistin-resistant genera (e.g., Morganella, Providencia, Proteus) or Stenotrophomonas maltophilia were excluded from further analysis (n = 421). Among the remaining 1,430 isolates, colistin resistance was confirmed in 279 by Etest® (19.5%) and 218 by BMD (15.3%). The Rapid Polymyxin™ NP test was compared with BMD (reference) to detect colistin resistance (specificity: 88.6%, sensitivity 71.1%). SuperPolymyxin™ medium is suitable to screen for fecal colonization with CRGN. The high proportion of colistin-susceptible isolates growing on SuperPolymyxin™ medium caused a high workload. The confirmation of CRGN with the Rapid Polymyxin™ NP Test could be a less labor-intensive alternative to BMD.
Collapse
Affiliation(s)
- Sara M Przybysz
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | | | - Robin Köck
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany.,Institute of Hygiene, University Hospital Münster, Münster, Germany.,Institute of Hygiene, DRK Kliniken Berlin, Berlin, Germany
| | - Karsten Becker
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Frieder Schaumburg
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| |
Collapse
|