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Li G, Wang L, Zhang H, Luan Y, Sun Q, Duo L. Study on the Role of ampG in the Regulation of Plasmid-Mediated ampC -Induced Expression in Klebsiella pneumoniae. Infect Drug Resist 2023; 16:5587-5598. [PMID: 37645559 PMCID: PMC10461740 DOI: 10.2147/idr.s421598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/26/2023] [Indexed: 08/31/2023] Open
Abstract
Objective In this study, we constructed ampG knock-out and knock-in strains from a clinically isolated Kp1strain carrying ampR-ampC in its plasmid and compared them with the Kp NTUH-K2044 strain to investigate the relationship between ampG and ampR-ampC-induced expression. Methods We created the ampG gene deletion mutant strains Kp1-ΔampG and Kp NTUH-K2044-ΔampG with pKO3-km plasmid using homologous recombination technology. We constructed the Kp NTUH-K2044-RC and Kp NTUH-K2044-ΔampG-RC drug resistance model strains with plasmid pACYC184. We constructed the ampG knock-in strains by introducing the ampG genes of Kp1, Enterobacter cloacae 029M, Pseudomonas aeruginosa PAO1, Escherichia coli ATCC25922, and Salmonella typhimurium LT2 into the ampG gene-deleted strains with carrier pet-30a. Real-time polymerase chain reaction (real-time PCR) was used to detect the relative expressions of ampC and ampG mRNAs. Results Compared with Kp1, the induction phenotype of the ampC of Kp1-ΔampG strain disappeared, the ampC expression was reduced, and the minimal inhibitory concentration (MIC) values of cefoxitin and ceftazidime significant decrease from 128 μg/mL to 1 μg/mL. Based on Kp1, five strain were successfully constructed to complement the ampG genes from five knock-in strain, and all of the above complemented strains showed inducible expression of ampC and restored the expression of ampG to varying degrees, as well as restored resistance to the antimicrobial drugs cefoxitin and ceftazidime (P < 0.05). The ampC and ampG genes were barely expressed in Kp NTUH-K2044-ΔampG-RC when compared with Kp NTUH-K2044-RC. The expressions of ampG and ampC in each knock-in strain were recovered, the induction phenotype of ampC was restored, and the MIC values of cefoxitin and ceftazidime were increased. (P < 0.05). Conclusion In this study, we found that ampG was an essential regulator for the plasmid-mediated ampC-induced expression in K. pneumoniae.
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Affiliation(s)
- Guiling Li
- Department of Clinical Laboratory, the Second Hospital Affiliated to Harbin Medical University, Harbin, Heilongjiang, 150086, People’s Republic of China
| | - Li Wang
- Department of Clinical Laboratory, School of Medicine, Chengdu Women’s and Children’s Central Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, People’s Republic of China
| | - Heguang Zhang
- Department of Clinical Laboratory, the Second Hospital Affiliated to Harbin Medical University, Harbin, Heilongjiang, 150086, People’s Republic of China
| | - Ying Luan
- Department of Clinical Laboratory, the Second Hospital Affiliated to Harbin Medical University, Harbin, Heilongjiang, 150086, People’s Republic of China
| | - Qi Sun
- Department of Clinical Laboratory, the Second Hospital Affiliated to Harbin Medical University, Harbin, Heilongjiang, 150086, People’s Republic of China
| | - Libo Duo
- Department of Clinical Laboratory, the Second Hospital Affiliated to Harbin Medical University, Harbin, Heilongjiang, 150086, People’s Republic of China
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Hussain HI, Aqib AI, Seleem MN, Shabbir MA, Hao H, Iqbal Z, Kulyar MFEA, Zaheer T, Li K. Genetic basis of molecular mechanisms in β-lactam resistant gram-negative bacteria. Microb Pathog 2021; 158:105040. [PMID: 34119627 PMCID: PMC8445154 DOI: 10.1016/j.micpath.2021.105040] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/25/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022]
Abstract
Antibiotic-resistant bacteria are considered one of the major global threats to human and animal health. The most harmful among the resistant bacteria are β-lactamase producing Gram-negative species (β-lactamases). β-lactamases constitute a paradigm shift in the evolution of antibiotic resistance. Therefore, it is imperative to present a comprehensive review of the mechanisms responsible for developing antimicrobial resistance. Resistance due to β-lactamases develops through a variety of mechanisms, and the number of resistant genes are involved that can be transferred between bacteria, mostly via plasmids. Over time, these new molecular-based resistance mechanisms have been progressively disclosed. The present review article provides information on the recent findings regarding the molecular mechanisms of resistance to β-lactams in Gram-negative bacteria, including CTX-M-type ESBLs with methylase activity, plasmids harbouring phages with β-lactam resistance genes, the co-presence of β-lactam resistant genes of unique combinations and the presence of β-lactam and non-β-lactam antibiotic-resistant genes in the same bacteria. Keeping in view, the molecular level resistance development, multifactorial and coordinated measures may be taken to counter the challenge of rapidly increasing β-lactam resistance.
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Affiliation(s)
- Hafiz Iftikhar Hussain
- Department of Pathology, Cholistan University of Veterinary and Animal Sciences, Bahawalpur, 63100, Pakistan
| | - Amjad Islam Aqib
- Department of Medicine, Cholistan University of Veterinary and Animal Sciences, Bahawalpur, 63100, Pakistan.
| | - Mohamed N Seleem
- Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, USA
| | | | - Haihong Hao
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural University, 430070, Wuhan, China
| | - Zahid Iqbal
- Department of Pharmacology, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, 518055, China.
| | | | - Tean Zaheer
- Department of Parasitology, University of Agriculture, Faisalabad, 38000, Pakistan
| | - Kun Li
- Institute of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, PR China.
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Realegeno S, Ward K, Garner OB, Yang S. Deceiving Phenotypic Susceptibility Results on a Klebsiella pneumoniae Blood Isolate Carrying Plasmid-Mediated AmpC Gene bla DHA-1. Front Cell Infect Microbiol 2021; 11:561880. [PMID: 33791229 PMCID: PMC8006929 DOI: 10.3389/fcimb.2021.561880] [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: 05/13/2020] [Accepted: 02/08/2021] [Indexed: 11/25/2022] Open
Abstract
Carbapenem-resistant Klebsiella pneumoniae (CRKP) frequently causes hospital-acquired infections and is associated with high morbidity and mortality. CRKP can have multiple resistance mechanisms and only a few can be routinely detected by commercial molecular or phenotypic assays making surveillance for CRKP particularly challenging. In this report, we identified and characterized an unusual non–carbapenemase-producing CRKP carrying a rare plasmid-borne inducible AmpC gene, blaDHA-1. The isolate was recovered from blood culture of a 67-year-old female presenting with sepsis post bladder surgery and ureteral stent removal. The primary isolate displayed an indeterminate susceptibility pattern for ceftriaxone by broth microdilution, but was susceptible by disk diffusion with one colony growing within the zone of inhibition. The ceftriaxone resistant colony was sub-cultured and had a minimum inhibitory concentration (MIC) of 2 ug/ml for imipenem (intermediate) and a zone size of 18 mm for ertapenem (resistant), but remained susceptible to cefepime and meropenem. Further phenotypic characterization of this sub-cultured isolate showed carbapenemase activity. Whole genome sequencing (WGS) revealed the presence of two subpopulations of a K. pneumoniae (MLST sequence type 11) from the primary blood culture isolate: one pan-susceptible to beta-lactams tested and the other resistant to the 3rd generation cephalosporins and ertapenem. WGS analysis identified the resistant K. pneumoniae harboring IncFIB(K) and IncR plasmids and the presence of plasmid-borne beta-lactam resistance genes blaOXA-1 and blaDHA-1, an inducible AmpC gene. Additional resistance genes against quinolones (aac(6′)-Ib-cr, oqxA, oqB), aminoglycoside (aph(3′)-Ia), sulfonamide (sul1), and tetracycline (tet(A)) were also identified. DHA-1 positive K. pneumoniae have been previously identified outside the US, particularly in Asia and Europe, but limited cases have been reported in the United States and may be underrecognized. Our study highlights the importance of using both extended phenotypic testing and WGS to identify emerging resistance mechanisms in clinical Enterobacterales isolates with unusual antimicrobial resistance patterns.
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Affiliation(s)
- Susan Realegeno
- UCLA Clinical Microbiology Laboratory, Department of Pathology & Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Kevin Ward
- UCLA Clinical Microbiology Laboratory, Department of Pathology & Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Omai B Garner
- UCLA Clinical Microbiology Laboratory, Department of Pathology & Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Shangxin Yang
- UCLA Clinical Microbiology Laboratory, Department of Pathology & Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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The Structure of ampG Gene in Pseudomonas aeruginosa and Its Effect on Drug Resistance. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2018; 2018:7170416. [PMID: 30598711 PMCID: PMC6287161 DOI: 10.1155/2018/7170416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/20/2018] [Accepted: 09/24/2018] [Indexed: 11/18/2022]
Abstract
In order to study the relationship between the structure and function of AmpG, structure, site-specific mutation, and gene complementary experiments have been performed against the clinical isolates of Pseudomonas aeruginosa. We found that there are 51 nucleotide variations at 34 loci over the ampG genes from 24 of 35 P. aeruginosa strains detected, of which 7 nucleotide variations resulted in amino acid change. The ampG variants with the changed nucleotides (amino acids) could complement the function of ampG deleted PA01 (PA01ΔG). The ampicillin minimum inhibitory concentration (MIC) of PA01ΔG complemented with 32 ampG variants was up to 512 μg/ml, similar to the original PA01 (P. aeruginosa PA01). Furthermore, site-directed mutation of two conservative amino acids (I53 and W90) showed that when I53 was mutated to 53S or 53T (I53S or I53T), the ampicillin MIC level dropped drastically, and the activity of AmpC β-lactamase decreased as well. By contrast, the ampicillin MIC and the activity of AmpC β-lactamase remained unchanged for W90R and W90S mutants. Our studies demonstrated that although nucleotide variations occurred in most of the ampG genes, the structure of AmpG protein in clinical isolates is stable, and conservative amino acid is necessary to maintain normal function of AmpG.
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Jones AK, Ranjitkar S, Lopez S, Li C, Blais J, Reck F, Dean CR. Impact of Inducible blaDHA-1 on Susceptibility of Klebsiella pneumoniae Clinical Isolates to LYS228 and Identification of Chromosomal mpl and ampD Mutations Mediating Upregulation of Plasmid-Borne blaDHA-1 Expression. Antimicrob Agents Chemother 2018; 62:e01202-18. [PMID: 30061296 PMCID: PMC6153798 DOI: 10.1128/aac.01202-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 07/27/2018] [Indexed: 01/18/2023] Open
Abstract
Twenty-three Klebsiella pneumoniae (blaDHA-1) clinical isolates exhibited a range of susceptibilities to LYS228, with MICs of ≥8 μg/ml for 9 of these. Mutants with decreased susceptibility to LYS228 and upregulated expression of blaDHA-1 were selected from representative isolates. These had mutations in the chromosomal peptidoglycan recycling gene mpl or ampD Preexisting mpl mutations were also found in some of the clinical isolates examined, and these had strongly upregulated expression of blaDHA-1.
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Affiliation(s)
- Adriana K Jones
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Srijan Ranjitkar
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Sara Lopez
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Cindy Li
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Johanne Blais
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Folkert Reck
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Charles R Dean
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
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Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
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Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Xia J, Gao J, Tang W. Nosocomial infection and its molecular mechanisms of antibiotic resistance. Biosci Trends 2016; 10:14-21. [PMID: 26877142 DOI: 10.5582/bst.2016.01020] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Nosocomial infection is a kind of infection, which is spread in various hospital environments, and leads to many serious diseases (e.g. pneumonia, urinary tract infection, gastroenteritis, and puerperal fever), and causes higher mortality than community-acquired infection. Bacteria are predominant among all the nosocomial infection-associated pathogens, thus a large number of antibiotics, such as aminoglycosides, penicillins, cephalosporins, and carbapenems, are adopted in clinical treatment. However, in recent years antibiotic resistance quickly spreads worldwide and causes a critical threat to public health. The predominant bacteria include Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Acinetobacter baumannii. In these bacteria, resistance emerged from antibiotic resistant genes and many of those can be exchanged between bacteria. With technical advances, molecular mechanisms of resistance have been gradually unveiled. In this review, recent advances in knowledge about mechanisms by which (i) bacteria hydrolyze antibiotics (e.g. extended spectrum β-lactamases, (ii) AmpC β-lactamases, carbapenemases), (iii) avoid antibiotic targeting (e.g. mutated vanA and mecA genes), (iv) prevent antibiotic permeation (e.g. porin deficiency), or (v) excrete intracellular antibiotics (e.g. active efflux pump) are summarized.
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Affiliation(s)
- Jufeng Xia
- Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, The University of Tokyo
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