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Mobile Oxazolidinone Resistance Genes in Gram-Positive and Gram-Negative Bacteria. Clin Microbiol Rev 2021; 34:e0018820. [PMID: 34076490 DOI: 10.1128/cmr.00188-20] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Seven mobile oxazolidinone resistance genes, including cfr, cfr(B), cfr(C), cfr(D), cfr(E), optrA, and poxtA, have been identified to date. The cfr genes code for 23S rRNA methylases, which confer a multiresistance phenotype that includes resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A compounds. The optrA and poxtA genes code for ABC-F proteins that protect the bacterial ribosomes from the inhibitory effects of oxazolidinones. The optrA gene confers resistance to oxazolidinones and phenicols, while the poxtA gene confers elevated MICs or resistance to oxazolidinones, phenicols, and tetracycline. These oxazolidinone resistance genes are most frequently found on plasmids, but they are also located on transposons, integrative and conjugative elements (ICEs), genomic islands, and prophages. In these mobile genetic elements (MGEs), insertion sequences (IS) most often flanked the cfr, optrA, and poxtA genes and were able to generate translocatable units (TUs) that comprise the oxazolidinone resistance genes and occasionally also other genes. MGEs and TUs play an important role in the dissemination of oxazolidinone resistance genes across strain, species, and genus boundaries. Most frequently, these MGEs also harbor genes that mediate resistance not only to antimicrobial agents of other classes, but also to metals and biocides. Direct selection pressure by the use of antimicrobial agents to which the oxazolidinone resistance genes confer resistance, but also indirect selection pressure by the use of antimicrobial agents, metals, or biocides (the respective resistance genes against which are colocated on cfr-, optrA-, or poxtA-carrying MGEs) may play a role in the coselection and persistence of oxazolidinone resistance genes.
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Mendes RE, Deshpande L, Streit JM, Sader HS, Castanheira M, Hogan PA, Flamm RK. ZAAPS programme results for 2016: an activity and spectrum analysis of linezolid using clinical isolates from medical centres in 42 countries. J Antimicrob Chemother 2019; 73:1880-1887. [PMID: 29659858 DOI: 10.1093/jac/dky099] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/02/2018] [Indexed: 12/11/2022] Open
Abstract
Objectives To report the linezolid activity, resistance mechanisms and epidemiological typing of selected isolates observed during the 2016 Zyvox® Annual Appraisal of Potency and Spectrum (ZAAPS) programme. Methods A total of 8325 organisms were consecutively collected from 76 centres in 42 countries (excluding the USA). Broth microdilution susceptibility testing was performed and isolates displaying linezolid MICs of ≥4 mg/L were molecularly characterized. Results Linezolid inhibited 99.8% of all Gram-positive pathogens at the respective susceptible breakpoints and showed a modal MIC of 1 mg/L, except for CoNS, for which the modal MIC result was 0.5 mg/L. Among isolates displaying linezolid MICs of ≥4 mg/L, one Staphylococcus aureus (linezolid MIC of 4 mg/L) harboured cfr and belonged to ST72, while four CoNS (MICs of 16-32 mg/L; ST2) showed drug target alterations. Two Enterococcus faecium (ST117) from a single site in Rome were linezolid non-susceptible (MICs of 8 mg/L) and had G2576T mutations. Eight linezolid-non-susceptible Enterococcus faecalis (MICs of 4 mg/L; 4 sites in 4 countries; ST256, ST480, ST766 and ST775) carried optrA and isolates carrying optrA from the same medical centre were genetically related. One Streptococcus gallolyticus (MIC of 4 mg/L) and one Streptococcus mitis (MIC of 16 mg/L) carried optrA and G2576T mutations, respectively. Conclusions These results document the continued long-term in vitro potency of linezolid. Alterations in the 23S rRNA and/or L3/L4 proteins remain the main oxazolidinone resistance mechanisms in E. faecium and CoNS, whereas optrA emerged as the sole mechanism in E. faecalis. Surveillance and infection control will be important strategies to detect optrA and prevent it from disseminating.
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Paukner S, Riedl R. Pleuromutilins: Potent Drugs for Resistant Bugs-Mode of Action and Resistance. Cold Spring Harb Perspect Med 2017; 7:a027110. [PMID: 27742734 PMCID: PMC5204327 DOI: 10.1101/cshperspect.a027110] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pleuromutilins are antibiotics that selectively inhibit bacterial translation and are semisynthetic derivatives of the naturally occurring tricyclic diterpenoid pleuromutilin, which received its name from the pleuromutilin-producing fungus Pleurotus mutilus Tiamulin and valnemulin are two established derivatives in veterinary medicine for oral and intramuscular administration. As these early pleuromutilin drugs were developed at a time when companies focused on major antibacterial classes, such as the β-lactams, and resistance was not regarded as an issue, interest in antibiotic research including pleuromutilins was limited. Over the last decade or so, there has been a resurgence in interest to develop this class for human use. This has resulted in a topical derivative, retapamulin, and additional derivatives in clinical development. The most advanced compound is lefamulin, which is in late-stage development for the intravenous and oral treatment of community-acquired bacterial pneumonia and acute bacterial skin infections. Overall, pleuromutilins and, in particular, lefamulin are characterized by potent activity against Gram-positive and fastidious Gram-negative pathogens as well as against mycoplasmas and intracellular organisms, such as Chlamydia spp. and Legionella pneumophila Pleuromutilins are unaffected by resistance to other major antibiotic classes, such as macrolides, fluoroquinolones, tetracyclines, β-lactam antibiotics, and others. Furthermore, pleuromutilins display very low spontaneous mutation frequencies and slow, stepwise resistance development at sub-MIC in vitro. The potential for resistance development in clinic is predicted to be slow as confirmed by extremely low resistance rates to this class despite the use of pleuromutilins in veterinary medicine for >30 years. Although rare, resistant strains have been identified in human- and livestock-associated environments and as with any antibiotic class, require close monitoring as well as prudent use in veterinary medicine. This review focuses on the structural characteristics, mode of action, antibacterial activity, and resistance development of this potent and novel antibacterial class for systemic use in humans.
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Sader HS, Castanheira M, Farrell DJ, Flamm RK, Mendes RE, Jones RN. Tigecycline antimicrobial activity tested against clinical bacteria from Latin American medical centres: results from SENTRY Antimicrobial Surveillance Program (2011-2014). Int J Antimicrob Agents 2016; 48:144-50. [PMID: 27291285 DOI: 10.1016/j.ijantimicag.2016.04.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/04/2016] [Accepted: 04/16/2016] [Indexed: 11/29/2022]
Abstract
Bacterial organisms (n = 13,494) were consecutively collected in 2011-2014 from 21 Latin American medical centres (11 nations). Antimicrobial susceptibility was determined by broth microdilution at a central laboratory. Tigecycline was very active against Gram-positive organisms, with MIC50/90 values of 0.06/0.06 µg/mL for Staphylococcus aureus (n = 2878), 0.06/0.12 µg/mL for coagulase-negative staphylococci (n = 880), 0.06/0.06 µg/mL for enterococci (n = 708) and ≤0.03/≤0.03-0.06 µg/mL for streptococci (n = 1352). All Gram-positive species exhibited 100.0% susceptibility (FDA and/or EUCAST criteria), except for Streptococcus pneumoniae (99.8% susceptible). The S. aureus oxacillin resistance rate varied from 28.0% (Brazil) to 55.0% (Argentina), and the overall vancomycin resistance rate was 15.5% (Enterococcus faecium, 50.3%; and Enterococcus faecalis, 2.3%). The E. faecium vancomycin resistance rate varied from a low (26.3%) in Argentina to a high (71.7%) in Brazil. Against Enterobacteriaceae (n = 4543), tigecycline MIC50/90 values were 0.25/1 µg/mL; 98.3% and 94.2% of strains were considered susceptible according to FDA and EUCAST breakpoints, respectively. Overall, 37.7% and 57.3% of Escherichia coli and Klebsiella pneumoniae exhibited the CLSI ESBL screening phenotype. The highest CLSI ESBL screening phenotype rates among E. coli and Klebsiella spp. strains were observed for isolates collected from Mexico (69.9%) and Chile (69.9%), respectively. Occurrence of carbapenem-resistant Enterobacteriaceae was substantially higher in Brazil (9.0%) and Argentina (6.3%) compared with Chile and Mexico (0.4-0.7%). Tigecycline was also active against Acinetobacter spp. (MIC50/90, 1/2 µg/mL; 92.3/72.1% inhibited at ≤2/≤1 µg/mL) and Stenotrophomonas maltophilia (MIC50/90, 0.5/2 µg/mL; 91.5/83.0% inhibited at ≤2/≤1 µg/mL).
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Affiliation(s)
- Helio S Sader
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA.
| | - Mariana Castanheira
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA
| | - David J Farrell
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA
| | - Robert K Flamm
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA
| | - Rodrigo E Mendes
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA
| | - Ronald N Jones
- JMI Laboratories, 345 Beaver Kreek Centre, Ste A, North Liberty, IA 52317, USA
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Update on linezolid in vitro activity through the Zyvox Annual Appraisal of Potency and Spectrum Program, 2013. Antimicrob Agents Chemother 2015; 59:2454-7. [PMID: 25645839 DOI: 10.1128/aac.04784-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Linezolid showed MIC50s and MIC90s of 1 μg/ml (for both) against Staphylococcus aureus. Two S. aureus strains exhibited higher MICs (4 to 8 μg/ml) caused by cfr and/or target site mutations, including the first detection of cfr in Poland. Linezolid (MIC50 and MIC90, 0.5 and 1 μg/ml) had potent MICs against coagulase-negative staphylococci (CoNS). Four CoNS had MICs of 16 to 128 μg/ml due to alterations in 23S rRNA and/or L3/L4. Linezolid inhibited all enterococci and streptococci at ≤2 μg/ml, except for one Enterococcus faecium strain (MIC, 8 μg/ml; G2576T [Escherichia coli numbering] mutation).
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Sahm DF, Deane J, Bien PA, Locke JB, Zuill DE, Shaw KJ, Bartizal KF. Results of the Surveillance of Tedizolid Activity and Resistance Program: in vitro susceptibility of Gram-positive pathogens collected in 2011 and 2012 from the United States and Europe. Diagn Microbiol Infect Dis 2015; 81:112-8. [DOI: 10.1016/j.diagmicrobio.2014.08.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/22/2014] [Accepted: 08/23/2014] [Indexed: 10/24/2022]
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Tamma PD, Robinson GL, Gerber JS, Newland JG, DeLisle CM, Zaoutis TE, Milstone AM. Pediatric Antimicrobial Susceptibility Trends across the United States. Infect Control Hosp Epidemiol 2015; 34:1244-51. [DOI: 10.1086/673974] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objective.Antimicrobial susceptibility patterns across US pediatric healthcare institutions are unknown. A national pooled pediatric antibiogram (1) identifies nationwide trends in antimicrobial resistance, (2) allows across-hospital benchmarking, and (3) provides guidance for empirical antimicrobial regimens for institutions unable to generate pediatric antibiograms.Methods.In January 2012, a request for submission of pediatric antibiograms between 2005 and 2011 was sent to 233 US hospitals. A summary antibiogram was compiled from participating institutions to generate proportions of antimicrobial susceptibility. Temporal and regional comparisons were evaluated using χ² tests and logistic regression, respectively.Results.Of 200 institutions (85%) responding to our survey, 78 (39%) reported generating pediatric antibiograms, and 55 (71%) submitted antibiograms. Carbapenems had the highest activity against the majority of gram-negative organisms tested, but no antibiotic had more than 90% activity against Pseudomonas aeruginosa. Approximately 50% of all Staphylococcus aureus isolates were methicillin resistant. Western hospitals had significantly lower proportions of S. aureus that were methicillin resistant compared with all other regions tested. Overall, 21% of S. aureus isolates had resistance to clindamycin. Among Enterococcus faecium isolates, the prevalence of susceptibility to ampicillin (25%) and vancomycin (45%) was low but improved over time (P < .01), and 8% of E. faecium isolates were resistant to linezolid. Southern hospitals reported significantly higher prevalence of E. faecium with susceptibilities to ampicillin, vancomycin, and linezolid compared with the other 3 regions (P < .01).Conclusions.A pooled, pediatric antibiogram can identify nationwide antimicrobial resistance patterns for common pathogens and might serve as a useful tool for benchmarking resistance and informing national prescribing guidelines for children.
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Hegstad K, Longva JÅ, Hide R, Aasnæs B, Lunde TM, Simonsen GS. Cluster of linezolid-resistant Enterococcus faecium ST117 in Norwegian hospitals. ACTA ACUST UNITED AC 2014; 46:712-5. [DOI: 10.3109/00365548.2014.923107] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Mendes RE, Deshpande LM, Jones RN. Linezolid update: stable in vitro activity following more than a decade of clinical use and summary of associated resistance mechanisms. Drug Resist Updat 2014; 17:1-12. [PMID: 24880801 DOI: 10.1016/j.drup.2014.04.002] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Linezolid, approved for clinical use since 2000, has become an important addition to the anti-Gram-positive infection armamentarium. This oxazolidinone drug has in vitro and in vivo activity against essentially all Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The in vitro activity of linezolid was well documented prior to its clinical application, and several ongoing surveillance studies demonstrated consistent and potent results during the subsequent years of clinical use. Emergence of resistance has been limited and associated with invasive procedures, deep organ involvement, presence of foreign material and mainly prolonged therapy. Non-susceptible organisms usually demonstrate alterations in the 23S rRNA target, which remain the main resistance mechanism observed in enterococci; although a few reports have described the detection of cfr-mediated resistance in Enterococcus faecalis. S. aureus isolates non-susceptible to linezolid remain rare in large surveillance studies. Most isolates harbour 23S rRNA mutations; however, cfr-carrying MRSA isolates have been observed in the United States and elsewhere. It is still uncertain whether the occurrences of such isolates are becoming more prevalent. Coagulase-negative isolates (CoNS) resistant to linezolid were uncommon following clinical approval. Surveillance data have indicated that CoNS isolates, mainly Staphylococcus epidermidis, currently account for the majority of Gram-positive organisms displaying elevated MIC results to linezolid. In addition, these isolates frequently demonstrate complex and numerous resistance mechanisms, such as alterations in the ribosomal proteins L3 and/or L4 and/or presence of cfr and/or modifications in 23S rRNA. The knowledge acquired during the past decades on this initially used oxazolidinone has been utilized for developing new candidate agents, such as tedizolid and radezolid, and as linezolid patents soon begin to expire, generic brands will certainly become available. These events will likely establish a new chapter for this successful class of antimicrobial agents.
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Affiliation(s)
| | | | - Ronald N Jones
- JMI Laboratories, North Liberty, IA 52317, USA; Tufts University School of Medicine, Boston, MA 02111, USA
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Mendes RE, Hogan PA, Streit JM, Jones RN, Flamm RK. Zyvox® Annual Appraisal of Potency and Spectrum (ZAAPS) program: report of linezolid activity over 9 years (2004-12). J Antimicrob Chemother 2014; 69:1582-8. [PMID: 24468866 DOI: 10.1093/jac/dkt541] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To summarize the activity and spectrum of linezolid and comparators tested against 7972 Gram-positive clinical isolates as part of the Zyvox(®) Annual Appraisal of Potency and Spectrum (ZAAPS) Program for 2012. Moreover, to provide molecular characterization for associated resistance mechanisms and epidemiological typing. METHODS A total of 7972 isolates were collected from 73 medical centres (33 countries) on five continents. Isolates were tested for susceptibility by broth microdilution following the CLSI M07-A9 document. MIC interpretations were based on CLSI and EUCAST criteria. RESULTS Linezolid showed MIC50 and MIC90 results of 1 and 2 mg/L, respectively, when tested against Staphylococcus aureus. These isolates were inhibited by linezolid at ≤2 mg/L, except for four S. aureus exhibiting higher MIC values (4-8 mg/L), which had cfr and/or target site mutations, including a first detection of cfr in an isolate from Brazil. Coagulase-negative staphylococci (CoNS) were susceptible to linezolid (MIC50/90, 0.5/1 mg/L), with only eight isolates exhibiting high MIC results (16-32 mg/L). These CoNS had cfr and/or single or multiple target site alterations in 23S rRNA and/or ribosomal proteins (L3, L4). The same species of linezolid-resistant CoNS collected from the same hospital were clonally related to those observed in previously surveyed years. Linezolid exhibited stable modal MIC and MIC50 results when tested against enterococci, regardless of the species or vancomycin resistance phenotype; in addition, linezolid inhibited all streptococci at ≤2 mg/L. CONCLUSIONS This surveillance report documents stable linezolid activity and susceptibility rates against a large and longitudinal collection of clinical isolates worldwide.
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Affiliation(s)
| | | | | | - Ronald N Jones
- JMI Laboratories, North Liberty, IA 52317, USA Tufts University School of Medicine, Boston, MA 02111, USA
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Flamm RK, Mendes RE, Ross JE, Sader HS, Jones RN. An international activity and spectrum analysis of linezolid: ZAAPS Program results for 2011. Diagn Microbiol Infect Dis 2013; 76:206-13. [DOI: 10.1016/j.diagmicrobio.2013.01.025] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 01/31/2013] [Indexed: 12/18/2022]
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Resistencia al linezolid: ¿una curiosidad de laboratorio o un problema clínico relevante? Enferm Infecc Microbiol Clin 2013; 31:127-9. [DOI: 10.1016/j.eimc.2013.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 12/22/2012] [Accepted: 01/05/2013] [Indexed: 11/19/2022]
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