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George NL, Bennett EC, Orlando BJ. Guarding the walls: the multifaceted roles of Bce modules in cell envelope stress sensing and antimicrobial resistance. J Bacteriol 2024:e0012324. [PMID: 38869304 DOI: 10.1128/jb.00123-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024] Open
Abstract
Bacteria have developed diverse strategies for defending their cell envelopes from external threats. In Firmicutes, one widespread strategy is to use Bce modules-membrane protein complexes that unite a peptide-detoxifying ABC transporter with a stress response coordinating two-component system. These modules provide specific, front-line defense for a wide variety of antimicrobial peptides and small molecule antibiotics as well as coordinate responses for heat, acid, and oxidative stress. Because of these abilities, Bce modules play important roles in virulence and the development of antibiotic resistance in a variety of pathogens, including Staphylococcus, Streptococcus, and Enterococcus species. Despite their importance, Bce modules are still poorly understood, with scattered functional data in only a small number of species. In this review, we will discuss Bce module structure in light of recent cryo-electron microscopy structures of the B. subtilis BceABRS module and explore the common threads and variations-on-a-theme in Bce module mechanisms across species. We also highlight the many remaining questions about Bce module function. Understanding these multifunctional membrane complexes will enhance our understanding of bacterial stress sensing and may point toward new therapeutic targets for highly resistant pathogens.
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Affiliation(s)
- Natasha L George
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Ellen C Bennett
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Benjamin J Orlando
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
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2
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Kang YR, Chung DR, Ko JH, Huh K, Cho SY, Kang CI, Peck KR. Genetic alterations in methicillin-susceptible Staphylococcus aureus associated with high vancomycin minimum inhibitory concentration. Int J Antimicrob Agents 2023; 62:106971. [PMID: 37716577 DOI: 10.1016/j.ijantimicag.2023.106971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 08/21/2023] [Accepted: 09/09/2023] [Indexed: 09/18/2023]
Abstract
BACKGROUND There are many reports on gene mutations observed in methicillin-resistant Staphylococcus aureus (MRSA) showing reduced susceptibility to vancomycin. However, there are limited studies on the genetic alterations that contribute to high vancomycin minimum inhibitory concentrations (MICs) in methicillin-susceptible S. aureus (MSSA). This study aimed to compare MSSA strains with high vancomycin MICs with those with low MICs, and to identify specific genetic alterations associated with increased vancomycin MICs. METHODS In total, 124 MSSA strains were analysed, with 62 having vancomycin MICs of 1-2 mg/L (MS-HV) and the remaining 62 having MICs <1 mg/L (MS-LV) as control. Polymerase chain reaction amplification and sequencing were conducted to identify point mutations and amino acid changes in the vraSR, graRS and walRK operons and rpoB gene. The number of single nucleotide polymorphisms (SNPs) and specific mutations in the indicated gene were compared between the two groups. RESULTS The MS-HV strains had a significantly higher median number of SNPs in studied genes than the MS-LV strains (5 vs 3; P < 0.0001), with higher frequency of SNPs in the graR and walK genes. The MS-HV strains also displayed a significantly higher prevalence of specific mutations in the graR gene (V135I, I136V and V136I) compared with the MS-LV strains. The odds of having a high vancomycin MIC was 5.54 times higher in strains with a mutation in the graR gene, and 5.32 times higher in strains with a mutation in the walK gene, compared with those without these mutations. CONCLUSIONS Mutations in the graR and walK genes may contribute to reduced vancomycin susceptibility in MSSA. This study gives key insights into the mechanisms underlying this phenomenon.
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Affiliation(s)
- Yu Ri Kang
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Asia Pacific Foundation for Infectious Diseases, Seoul, Republic of Korea
| | - Doo Ryeon Chung
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Asia Pacific Foundation for Infectious Diseases, Seoul, Republic of Korea; Centre for Infection Prevention and Control, Samsung Medical Centre, Seoul, Republic of Korea.
| | - Jae-Hoon Ko
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyungmin Huh
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Asia Pacific Foundation for Infectious Diseases, Seoul, Republic of Korea
| | - Sun Young Cho
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Centre for Infection Prevention and Control, Samsung Medical Centre, Seoul, Republic of Korea
| | - Cheol-In Kang
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyong Ran Peck
- Division of Infectious Diseases, Department of Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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Chen L, Wang Z, Xu T, Ge H, Zhou F, Zhu X, Li X, Qu D, Zheng C, Wu Y, Zhao K. The Role of graRS in Regulating Virulence and Antimicrobial Resistance in Methicillin-Resistant Staphylococcus aureus. Front Microbiol 2021; 12:727104. [PMID: 34484169 PMCID: PMC8415711 DOI: 10.3389/fmicb.2021.727104] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/21/2021] [Indexed: 11/29/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of both community- and hospital-associated infections. The antibiotic resistance and virulence characteristics of MRSA are largely regulated by two-component signal transduction systems (TCS) including the graRS TCS. To make a relatively comprehensive insight into graRS TCS in MRSA, the bioinformatics analysis of dataset GSE26016 (a S. aureus HG001 WT strain vs. the ΔgraRS mutant) from Gene Expression Omnibus (GEO) database was performed, and a total of 563 differentially expressed genes (DEGs) were identified. GO analysis revealed that the DEGs were mainly enriched in the “de novo” IMP biosynthetic process, lysine biosynthetic process via diaminopimelate, and pathogenesis; and they were mainly enriched in purine metabolism, lysine biosynthesis, and monobactam biosynthesis in KEGG analysis. WGCNA suggested that the turquoise module was related to the blue module, and the genes in these two modules were associated with S. aureus virulence and infection. To investigate the role of graRS in bacterial virulence, a graRS knockout mutant (ΔgraRS) was constructed using MRSA USA500 2,395 strain as a parent strain. Compared to the wild-type strain, the USA500ΔgraRS showed reduced staphyloxanthin production, retarded coagulation, weaker hemolysis on blood agar plates, and a decreased biofilm formation. These altered phenotypes were restored by the complementation of a plasmid-expressed graRS. Meanwhile, an expression of the virulence-associated genes (coa, hla, hlb, agrA, and mgrA) was downregulated in the ΔgraRS mutant. Consistently, the A549 epithelial cells invasion of the ΔgraRS mutant was 4-fold lower than that of the USA500 wild-type strain. Moreover, on the Galleria mellonella infection model, the survival rate at day 5 post infection in the USA500ΔgraRS group (55%) was obviously higher than that in the USA500 group (20%), indicating graRS knockout leads to a decreased virulence in vivo. In addition, the deletion of the graRS in the MRSA USA500 strain resulted in its increased susceptibilities to ampicillin, oxacillin, vancomycin, and gentamicin. Our work suggests that the graRS TCS plays an important role in regulating S. aureus virulence in vitro and in vivo and modulate bacterial resistance to various antibiotics.
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Affiliation(s)
- Le Chen
- Department of Otolaryngology-Head and Neck Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China
| | - Zihui Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Tao Xu
- Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China.,State Key Laboratory of Genetic Engineering, School of Life Science, Fudan University, Shanghai, China.,Key Laboratory of Medical Molecular Virology (MOE/MOH/CAMS) and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Hongfei Ge
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Fangyue Zhou
- Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
| | - Xiaoyi Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Xianhui Li
- Department of Otolaryngology, The Third Affiliated Hospital of Wenzhou Medical University, Ruian, Zhejiang, China
| | - Di Qu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Chunquan Zheng
- Department of Otolaryngology-Head and Neck Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China
| | - Yang Wu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Keqing Zhao
- Department of Otolaryngology-Head and Neck Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China
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4
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Mohapatra SS, Dwibedy SK, Padhy I. Polymyxins, the last-resort antibiotics: Mode of action, resistance emergence, and potential solutions. J Biosci 2021. [PMID: 34475315 PMCID: PMC8387214 DOI: 10.1007/s12038-021-00209-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Infections caused by multi-drug resistant (MDR) bacterial pathogens are a leading cause of mortality and morbidity across the world. Indiscriminate use of broad-spectrum antibiotics has seriously affected this situation. With the diminishing discovery of novel antibiotics, new treatment methods are urgently required to combat MDR pathogens. Polymyxins, the cationic lipopeptide antibiotics, discovered more than half a century ago, are considered to be the last-line of antibiotics available at the moment. This antibiotic shows a great bactericidal effect against Gram-negative bacteria. Polymyxins primarily target the bacterial membrane and disrupt them, causing lethality. Because of their membrane interacting mode of action, polymyxins cause nephrotoxicity and neurotoxicity in humans, limiting their usability. However, recent modifications in their chemical structure have been able to reduce the toxic effects. The development of better dosing regimens has also helped in getting better clinical outcomes in the infections caused by MDR pathogens. Since the mid-1990s the use of polymyxins has increased manifold in clinical settings, resulting in the emergence of polymyxin-resistant strains. The risk posed by the polymyxin-resistant nosocomial pathogens such as the Enterobacteriaceae group, Pseudomonas aeruginosa, and Acinetobacter baumannii, etc. is very serious considering these pathogens are resistant to almost all available antibacterial drugs. In this review article, the mode of action of the polymyxins and the genetic regulatory mechanism responsible for the emergence of resistance are discussed. Specifically, this review aims to update our current understanding in the field and suggest possible solutions that can be pursued for future antibiotic development. As polymyxins primarily target the bacterial membranes, resistance to polymyxins arises primarily by the modification of the lipopolysaccharides (LPS) in the outer membrane (OM). The LPS modification pathways are largely regulated by the bacterial two-component signal transduction (TCS) systems. Therefore, targeting or modulating the TCS signalling mechanisms can be pursued as an alternative to treat the infections caused by polymyxin-resistant MDR pathogens. In this review article, this aspect is also highlighted.
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Affiliation(s)
- Saswat S Mohapatra
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
| | - Sambit K Dwibedy
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
| | - Indira Padhy
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
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5
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Mohapatra SS, Dwibedy SK, Padhy I. Polymyxins, the last-resort antibiotics: Mode of action, resistance emergence, and potential solutions. J Biosci 2021; 46:85. [PMID: 34475315 PMCID: PMC8387214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/03/2021] [Indexed: 04/04/2024]
Abstract
Infections caused by multi-drug resistant (MDR) bacterial pathogens are a leading cause of mortality and morbidity across the world. Indiscriminate use of broad-spectrum antibiotics has seriously affected this situation. With the diminishing discovery of novel antibiotics, new treatment methods are urgently required to combat MDR pathogens. Polymyxins, the cationic lipopeptide antibiotics, discovered more than half a century ago, are considered to be the last-line of antibiotics available at the moment. This antibiotic shows a great bactericidal effect against Gram-negative bacteria. Polymyxins primarily target the bacterial membrane and disrupt them, causing lethality. Because of their membrane interacting mode of action, polymyxins cause nephrotoxicity and neurotoxicity in humans, limiting their usability. However, recent modifications in their chemical structure have been able to reduce the toxic effects. The development of better dosing regimens has also helped in getting better clinical outcomes in the infections caused by MDR pathogens. Since the mid1990s the use of polymyxins has increased manifold in clinical settings, resulting in the emergence of polymyxin-resistant strains. The risk posed by the polymyxin-resistant nosocomial pathogens such as the Enterobacteriaceae group, Pseudomonas aeruginosa, and Acinetobacter baumannii, etc. is very serious considering these pathogens are resistant to almost all available antibacterial drugs. In this review article, the mode of action of the polymyxins and the genetic regulatory mechanism responsible for the emergence of resistance are discussed. Specifically, this review aims to update our current understanding in the field and suggest possible solutions that can be pursued for future antibiotic development. As polymyxins primarily target the bacterial membranes, resistance to polymyxins arises primarily by the modification of the lipopolysaccharides (LPS) in the outer membrane (OM). The LPS modification pathways are largely regulated by the bacterial two-component signal transduction (TCS) systems. Therefore, targeting or modulating the TCS signalling mechanisms can be pursued as an alternative to treat the infections caused by polymyxin-resistant MDR pathogens. In this review article, this aspect is also highlighted.
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Affiliation(s)
- Saswat S Mohapatra
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
| | - Sambit K Dwibedy
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
| | - Indira Padhy
- Molecular Microbiology Lab, Department of Bioscience and Bioinformatics, Khallikote University, Konisi, Berhampur, 761 008 Odisha India
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6
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Bakthavatchalam YD, Babu P, Munusamy E, Dwarakanathan HT, Rupali P, Zervos M, John Victor P, Veeraraghavan B. Genomic insights on heterogeneous resistance to vancomycin and teicoplanin in Methicillin-resistant Staphylococcus aureus: A first report from South India. PLoS One 2019; 14:e0227009. [PMID: 31887179 PMCID: PMC6936811 DOI: 10.1371/journal.pone.0227009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/09/2019] [Indexed: 12/28/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is an important clinical concern in patients, and is often associated with significant disease burden and metastatic infections. There is an increasing evidence of heterogeneous vancomycin-intermediate S. aureus (hVISA) associated treatment failure. In this study, we aim to understand the molecular mechanism of teicoplanin resistant MRSA (TR-MRSA) and hVISA. A total of 482 MRSA isolates were investigated for these phenotypes. Of the tested isolates, 1% were identified as TR-MRSA, and 12% identified as hVISA. A highly diverse amino acid substitution was observed in tcaRAB, vraSR, and graSR genes in TR-MRSA and hVISA strains. Interestingly, 65% of hVISA strains had a D148Q mutation in the graR gene. However, none of the markers were reliable in differentiating hVISA from TR-MRSA. Significant pbp2 upregulation was noted in three TR-MRSA strains, which had teicoplanin MICs of 16 or 32 μg/ml, whilst significant pbp4 downregulation was not noted in these strains. In our study, multiple mutations were identified in the candidate genes, suggesting a complex evolutionary pathway involved in the development of TR-MRSA and hVISA strains.
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Affiliation(s)
| | - Priyanka Babu
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | - Elakkiya Munusamy
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | | | - Priscilla Rupali
- Infectious Diseases Training and Research Center (IDTRC), Christian Medical College, Vellore, India
| | - Marcus Zervos
- Infectious Diseases, Henry Ford Health System, Detroit, Michigan, United States of America
| | - Peter John Victor
- Department of critical care unit, Christian Medical College, Vellore, India
| | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
- * E-mail:
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7
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Silveira ACO, Caierão J, Silva CI, Anzai EK, McCulloch JA, d'Azevedo PA, Sincero TCM. Impact of mutations in hVISA isolates on decreased susceptibility to vancomycin, through population analyses profile - area under curve (PAP-AUC). Diagn Microbiol Infect Dis 2019; 95:114854. [PMID: 31366440 DOI: 10.1016/j.diagmicrobio.2019.06.006] [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] [Received: 11/03/2018] [Revised: 04/10/2019] [Accepted: 06/06/2019] [Indexed: 10/26/2022]
Abstract
We analyzed sequences of graSR, vraSR, walKR and rpoB genes in hVISA from Brazil. Five isolates showed mutations in at least one gene. rpoB H481N and graS T224I were the most frequent mutations, followed by graR D148Q and walK A468T. Our study reinforces the heterogeneity of genetic patterns among hVISA.
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Affiliation(s)
- A C O Silveira
- UFSC - Federal University of Santa Catarina, Florianópolis, - SC, Brazil; FURB - Regional University of Blumenau, Blumenau, - SC, Brazil.
| | - J Caierão
- UFRGS - Federal University of Rio Grande do Sul, Porto Alegre, - RS, Brazil
| | - C I Silva
- UFSC - Federal University of Santa Catarina, Florianópolis, - SC, Brazil
| | - E K Anzai
- FURB - Regional University of Blumenau, Blumenau, - SC, Brazil
| | - J A McCulloch
- USP - University of São Paulo, São Paulo, - SP, Brazil
| | - P A d'Azevedo
- UFCSPA - Federal University of Health Sciences of Porto Alegre, Porto Alegre, - RS, Brazil
| | - T C M Sincero
- UFSC - Federal University of Santa Catarina, Florianópolis, - SC, Brazil
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8
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Chan H, Ho J, Liu X, Zhang L, Wong SH, Chan MT, Wu WK. Potential and use of bacterial small RNAs to combat drug resistance: a systematic review. Infect Drug Resist 2017; 10:521-532. [PMID: 29290689 PMCID: PMC5736357 DOI: 10.2147/idr.s148444] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background Over the decades, new antibacterial agents have been developed in an attempt to combat drug resistance, but they remain unsuccessful. Recently, a novel class of bacterial gene expression regulators, bacterial small RNAs (sRNAs), has received increasing attention toward their involvement in antibiotic resistance. This systematic review aimed to discuss the potential of these small molecules as antibacterial drug targets. Methods Two investigators performed a comprehensive search of MEDLINE, EmBase, and ISI Web of Knowledge from inception to October 2016, without restriction on language. We included all in vitro and in vivo studies investigating the role of bacterial sRNA in antibiotic resistance. Risk of bias of the included studies was assessed by a modified guideline of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). Results Initial search yielded 432 articles. After exclusion of non-original articles, 20 were included in this review. Of these, all studies examined bacterial-type strains only. There were neither relevant in vivo nor clinical studies. The SYRCLE scores ranged from to 5 to 7, with an average of 5.9. This implies a moderate risk of bias. sRNAs influenced the antibiotics susceptibility through modulation of gene expression relevant to efflux pumps, cell wall synthesis, and membrane proteins. Conclusion Preclinical studies on bacterial-type strains suggest that modulation of sRNAs could enhance bacterial susceptibility to antibiotics. Further studies on clinical isolates and in vivo models are needed to elucidate the therapeutic value of sRNA modulation on treatment of multidrug-resistant bacterial infection.
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Affiliation(s)
- Hung Chan
- Department of Anesthesia and Intensive Care
| | - Jeffery Ho
- Department of Anesthesia and Intensive Care
| | | | - Lin Zhang
- Department of Anesthesia and Intensive Care.,State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences.,School of Biomedical Sciences, Faculty of Medicine
| | - Sunny Hei Wong
- State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences.,Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Shatin, Hong Kong
| | | | - William Kk Wu
- Department of Anesthesia and Intensive Care.,State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences
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9
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Lai C, Chuang W, Kong M, Siu H, Tsang D. Antimicrobial susceptibility in hospitals in Hong Kong: The current status 2009–2011. J Glob Antimicrob Resist 2014; 2:225-231. [DOI: 10.1016/j.jgar.2014.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/15/2014] [Accepted: 05/27/2014] [Indexed: 11/28/2022] Open
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10
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Kwok GML, O'Donoghue MM, Doddangoudar VC, Ho J, Boost MV. Reduced vancomycin susceptibility in porcine ST9 MRSA isolates. Front Microbiol 2013; 4:316. [PMID: 24298270 PMCID: PMC3829576 DOI: 10.3389/fmicb.2013.00316] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 10/07/2013] [Indexed: 11/13/2022] Open
Abstract
Porcine strains of livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) have been recognized in many countries and have been shown to be able to cause human infection. Resistance to non-beta lactam antibiotics has been reported but non-susceptibility to vancomycin, which is known to occur in human MRSA, has so far not been observed in LA-MRSA. Such resistance is typically fairly low level involving changes in the cell wall thickness. The development of resistance is usually preceded by presence of a sub-population having an increased MIC, which is selected for by exposure to vancomycin. This study investigated vancomycin susceptibility of one hundred porcine MRSA isolates using three MIC methods including spiral gradient endpoint (SGE) technique which allows visualization of more resistant sub-populations. SGE revealed 16 strains with an MIC above 2.0 mg/L, of which 14 were determined to have MIC 4 mg/L by agar dilution (AD). SGE revealed a further two isolates with MIC < 2 mg/L had a sub-population >2 mg/L. In addition, trailing endpoints not reaching resistance were present in 26 isolates with MIC < 2 mg/L. Sequencing of the genes of the VraSR/GraSR two component systems of ten of the resistant strains for comparison with susceptible strains revealed changes, including the presence of stop codons, in vraS and graR, but these were not consistent in all isolates. Other genetic changes may contribute to vancomycin non-susceptibility and require investigation. As failure to respond to treatment has been reported in clinical isolates with MIC > 1.5 mg/L, the presence of vancomycin non-susceptibility in porcine isolates is of concern and further monitoring of LA-MRSA is essential.
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Affiliation(s)
- Gabriella M L Kwok
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University Kowloon, Hong Kong
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11
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Jansen A, Szekat C, Schröder W, Wolz C, Goerke C, Lee JC, Türck M, Bierbaum G. Production of capsular polysaccharide does not influence Staphylococcus aureus vancomycin susceptibility. BMC Microbiol 2013; 13:65. [PMID: 23522028 PMCID: PMC3617075 DOI: 10.1186/1471-2180-13-65] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/04/2013] [Indexed: 01/12/2023] Open
Abstract
Background Diverse mechanisms (increased cell wall thickness, low cross linking, decreased autolysis, etc.) have been reported for Staphylococcus aureus strains with intermediate vancomycin susceptibility (VISA). This study was conducted to identify common mechanisms responsible for decreased vancomycin susceptibility in a VISA strain pair. Results Transcriptional profiling of the clinical heterogeneous VISA isolate SA137/93A and its spontaneous homogeneous mutant strain SA137/93G pointed to an increased capsule production in the strain pair compared to a susceptible control. Furthermore, transcript quantification of the gene cap5E, which is essential for capsule biosynthesis, revealed elevated levels in the VISA strains SA137/93A, SA137/93G and Mu50 in comparison with susceptible strains Reynolds, Newman and SA1450/94. The increased expression was observed in bacteria from exponential as well as stationary growth phase. However, suppression of type 5 capsule formation by expression of antisense RNA did not increase vancomycin susceptibility in the VISA strain SA137/93G. Likewise, construction of inducible mutants of S. aureus Newman or repair of capsule biosynthesis of S. aureus HG001 and S. aureus 1450/94 did not influence resistance to vancomycin. Furthermore, purified type 5 polysaccharide did not protect indicator strains from the action of vancomycin. Conclusions The VISA strain tested in this study displayed an increased production of type 5 capsular polysaccharide. However, the production of capsule material did not protect strain SA137/93G and three vancomycin sensitive strains in the presence of vancomycin and thus is not part of the resistance mechanism; however it may represent a by-product of VISA life style that is often characterized by a high sigma factor B activity.
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Affiliation(s)
- Andrea Jansen
- Institut für Medizinische Mikrobiologie, Immunologie und Parasitologie, Universitätsklinikum Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany
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12
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Epigallocatechin gallate induces upregulation of the two-component VraSR system by evoking a cell wall stress response in Staphylococcus aureus. Appl Environ Microbiol 2012; 78:7954-9. [PMID: 22941085 DOI: 10.1128/aem.02253-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We previously found that a short exposure of Staphylococcus aureus to subinhibitory (SI) doses of epigallocatechin gallate (EGCG) results in increased cell wall thickness, adaptation, and enhanced tolerance to cell-wall-targeted antibiotics. In this study, the response to EGCG of sigB and vraSR transcription factor mutants was characterized. We show that in contrast to the results observed for wild-type (WT) strains, an S. aureus 315 vraSR null mutant exposed to SI doses of EGCG did not exhibit increased tolerance to EGCG and oxacillin. A diminished increase in tolerance to ampicillin (from 16-fold to 4-fold) and no change in the magnitude of resistance to vancomycin were observed. Preexposure to EGCG enhanced the tolerance of wild-type and sigB null mutant cells to lysostaphin, but this enhancement was much weaker in the vraSR null mutant. Marked upregulation (about 60-fold) of vraR and upregulation of the peptidoglycan biosynthesis-associated genes murA, murF, and pbp2 (2-, 5-, and 6-fold, respectively) in response to SI doses of EGCG were determined by quantitative reverse transcription-PCR (qRT-PCR). EGCG also induced the promoter of sas016 (encoding a cell wall stress protein of unknown function which is not induced in vraSR null mutants) in a concentration-dependent manner, showing kinetics comparable to those of cell-wall-targeting antibiotics. Taken together, our results suggest that the two-component VraSR system is involved in modulating the cell response to SI doses of EGCG.
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Doddangoudar VC, O'Donoghue MM, Chong EYC, Tsang DNC, Boost MV. Role of stop codons in development and loss of vancomycin non-susceptibility in methicillin-resistant Staphylococcus aureus. J Antimicrob Chemother 2012; 67:2101-6. [DOI: 10.1093/jac/dks171] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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