Mechanisms of Antibiotic Resistance

2019 ◽  
Author(s):  
Ruaridh Buchanan ◽  
David Wareham
Keyword(s):  
Antibiotic Resistance ◽  
Dna Replication ◽  
Selection Pressure ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
Drug Resistant ◽  
Bacterial Cells ◽  
Gram Negative ◽  
The Times ◽  
Gram Negative Organisms

Although antibiotic resistance has come to the fore in the media and clinical practice relatively recently, it is by no means a new issue; Alexander Fleming discussed the risks of penicillin resistance more than sixty years ago, but even he was behind the times. Bacteria have been competing with each other for millions of years, producing compounds which kill or inhibit other species—it is not surprising that bacteria have evolved defence mechanisms. Current major concerns are the rise of pan-drug resistant gram-negative organisms and the spread of multi-drug resistant TB. Bacterial cells turn over rapidly—this rate of reproduction leads to many errors in DNA replication. Many of these mutations are deleterious to the organism, but others confer new properties, such as changing the structure of an enzyme. The application of selection pressure in the form of antimicrobial therapy leads to the survival of mutants that have randomly acquired resistance mechanisms. There are two useful ways to categorize resistance mechanisms: by how bacterial cells acquire them and by the physical mechanism of action. The types of acquisition have important infection control ramifications. Resistance can be subdivided into three separate categories: ● Intrinsic resistance— mechanisms hard coded into all members of a bacterial species at the chromosomal level. If an organism’s antibiogram suggests susceptibility to an agent to which it should be intrinsically resistant, further work should be done to check that the identification is correct. Examples include gram-negative bacteria being resistant to glycopeptides due to the outer cell membrane, anaerobes being resistant to aminoglycosides due to lack of an uptake mechanism, and amoxicillin resistance in Klebsiella due to beta-lactamase production. ● Mutational resistance—resistance that arises randomly due to DNA replication errors in conjunction with selection pressure applied by antimicrobial agents. This is the basis of the majority of the mechanisms detailed in this chapter. ● Transferrable resistance— mutational resistance that is passed horizontally from the bacterium in which it arose to another cell, possibly of a different species entirely. This happens through either transposons (DNA that incorporates into the bacterial chromosome) or plasmids (rings of DNA that replicate independent of the main chromosome).

scholarly journals Study of Antibiotic Resistance to Pseudomonas aeruginosa that Iisolate from Burns and Ggeneral Surgery from Al-Yarmouk Teaching Hospital

2018 ◽  
Vol 31 (1) ◽  
pp. 23
Author(s):  
Faraj Hato-Joni Al-Bidhani
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
General Surgery ◽  
Resistance Mechanisms ◽  
Ventilator Associated Pneumonia ◽  
Drug Resistant ◽  
Gram Negative ◽  
Sensitivity Rate ◽  
Males And Females ◽  
Medical Importance

     Pseudomonas aeruginosa is common gram negative rod – shaped bacterium, a species of considerable medical importance, P. aeruginosa is prototypical "multi drug resistant (MDR) Pathogen" that is recognised for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its associatation with serious illnesses – especially nosocomial infection such as ventilator – associated pneumonia and various sepsis syndromes. This study was conducted from March 2014 to July 2014, the patients were males and females. Total samples of 613 patients, selected from burns wards and general surgery wards, the samples were sending to teaching laboratories from the same hospital. The present study showed that the prevalence of sensitivity revealed that amikacin had the highest sensitivity (89,6%), followed by cefotaxime (66.2%), the optimal aminoglycosides in combination therapy with B-lactams was amikacin, followed by tobramycin and gentamycin, highest sensitivity rate showed that (95.2%) was found in the combination of amikacin with imipenem and piperacillin, (71.4%) were amikacin combination with cefotaxime ,(85.7%) were gentamycin with piperacillin , (71.4%) were gentamycin with cefotaxime, (95.2%) were  tobramycin with piperacillin,(76.2%)were tobramycin with carbenicillin, resistance of bacterials associated with reduced aminoglycoside accumulation the current study indicated that pseudomonas aeruginosa  was the most prevalent in burns and general surgery infection, these infections generally require treatment with a combination of antimicrobials inoder to achieve a greater baetericidal effect and reduce the levels of resistance .  

RND efflux pumps in Gram-negative bacteria; regulation, structure and role in antibiotic resistance

2020 ◽  
Vol 15 (2) ◽  
pp. 143-157 ◽  
Author(s):  
Abigail L Colclough ◽  
Ilyas Alav ◽  
Emily E Whittle ◽  
Hannah L Pugh ◽  
Elizabeth M Darby ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Efflux Pumps ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
New Information ◽  
Rnd Efflux Pumps ◽  
Gram Negative Organisms

Rresistance-nodulation-division (RND) efflux pumps in Gram-negative bacteria remove multiple, structurally distinct classes of antimicrobials from inside bacterial cells therefore directly contributing to multidrug resistance. There is also emerging evidence that many other mechanisms of antibiotic resistance rely on the intrinsic resistance conferred by RND efflux. In addition to their role in antibiotic resistance, new information has become available about the natural role of RND pumps including their established role in virulence of many Gram-negative organisms. This review also discusses the recent advances in understanding the regulation and structure of RND efflux pumps.

scholarly journals Occurrence of Multi-drug Resistant Bacteria in Some Selected Street Food Samples

2019 ◽  
pp. 1-8
Author(s):  
Mohamed H. El-Sayed
Keyword(s):  
Public Health ◽  
Antibiotic Resistance ◽  
Bacterial Species ◽  
Food Samples ◽  
Resistance Pattern ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Drug Resistant Bacteria

Antimicrobial resistance is a subject of great concern in the public health. The prevalence of antimicrobial resistance among food pathogens has increased during recent decades. Studying the incidence and antibiotic resistance pattern of bacterial species isolated from fish and vended street fruits.   Eleven fish swabs and thirteen sliced fruit samples were collected and prepared for isolation of bacterial species through inoculation onto selective and non-selective nutrient media. The grown colonies were purified through subculturing on nutrient agar plates then identified by morphological and biochemical methods. The obtained pure cultures were then kept on nutrient agar slants. Testing antibiotic resistance of the isolated bacterial strains was studied by Kirby-Bauer disk diffusion method on Mueller Hinton agar using ten antibiotics belonging to different classes. The resultant inhibition zone was interpreted according to Clinical Laboratory Standard Institute. Twenty-eight bacterial cultures were isolated from the collected food samples. The conventional identification using morphological and biochemical methods of these cultures revealed presence of three Gram positive species; Staphylococcus aureus, Streptococcus sp. and Bacillus subtilis in addition to four Gram negative; Escherichia coli, Brucella sp., Enterococcus faecalis and Proteus mirabilis. The incidence of the obtained bacterial species was arranged as 29.16% for both S. aureus and E. faecalis followed by Brucella sp. 16.66%; B. subtilis & E. coli 12.5% then Streptococcus sp. and P. mirabilis with an incidence of 8.33% each. Testing antibiotic resistance pattern of seven bacterial species against ten antibiotics showed that, among three Gram positive bacterial species, only one (33.33%) strain S. aureus exhibited resistance to six antibiotics; amoxicillin, erythromycin, ciprofloxacin, ceftriaxone, fluconazole and dicloxacillin. Among four Gram negative bacterial strains only one (25.0%) strain Enterococcus faecalis exhibited resistance to eight antibiotics; amoxicillin, streptomycin, chloramphenicol, cotrimoxazole, ciprofloxacin, ofloxacin, sparfloxacin and cloxacillin. Occurrence of multi-drug resistant bacteria in fish and vended street fruits poses not only risk of disease to the foods but public health hazard to food handlers and consumers in general. Also the result of this study recommended augmentin and cephazolin as good choice antibiotics for treatment of infection in the study area. 

scholarly journals Epidemiology and Mechanisms of Resistance of Extensively Drug Resistant Gram-Negative Bacteria

Antibiotics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 37 ◽  
Author(s):  
Emily M. Eichenberger ◽  
Joshua T. Thaden
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Mechanisms ◽  
Individual Treatment ◽  
Gram Negative Bacteria ◽  
Drug Resistant ◽  
Mechanisms Of Resistance ◽  
Gram Negative ◽  
Treatment Practices ◽  
Extensively Drug Resistant ◽  
Global Epidemiology

Antibiotic resistance has increased markedly in gram-negative bacteria over the last two decades, and in many cases has been associated with increased mortality and healthcare costs. The adoption of genotyping and next generation whole genome sequencing of large sets of clinical bacterial isolates has greatly expanded our understanding of how antibiotic resistance develops and transmits among bacteria and between patients. Diverse mechanisms of resistance, including antibiotic degradation, antibiotic target modification, and modulation of permeability through the bacterial membrane have been demonstrated. These fundamental insights into the mechanisms of gram-negative antibiotic resistance have influenced the development of novel antibiotics and treatment practices in highly resistant infections. Here, we review the mechanisms and global epidemiology of antibiotic resistance in some of the most clinically important resistance phenotypes, including carbapenem resistant Enterobacteriaceae, extensively drug resistant (XDR) Pseudomonas aeruginosa, and XDR Acinetobacter baumannii. Understanding the resistance mechanisms and epidemiology of these pathogens is critical for the development of novel antibacterials and for individual treatment decisions, which often involve alternatives to β-lactam antibiotics.

scholarly journals Evaluation of MicroScan Bacterial Identification Panels for Low-Resource Settings

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Sien Ombelet ◽  
Alessandra Natale ◽  
Jean-Baptiste Ronat ◽  
Olivier Vandenberg ◽  
Liselotte Hardy ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Ease Of Use ◽  
Bacterial Identification ◽  
Gram Positive ◽  
Gram Negative ◽  
Low Resource Settings ◽  
Low Resource ◽  
Bacillus Spp ◽  
Gram Negative Organisms ◽  
Instructions For Use

Bacterial identification is challenging in low-resource settings (LRS). We evaluated the MicroScan identification panels (Beckman Coulter, Brea, CA, USA) as part of Médecins Sans Frontières’ Mini-lab Project. The MicroScan Dried Overnight Positive ID Type 3 (PID3) panels for Gram-positive organisms and Dried Overnight Negative ID Type 2 (NID2) panels for Gram-negative organisms were assessed with 367 clinical isolates from LRS. Robustness was studied by inoculating Gram-negative species on the Gram-positive panel and vice versa. The ease of use of the panels and readability of the instructions for use (IFU) were evaluated. Of species represented in the MicroScan database, 94.6% (185/195) of Gram-negative and 85.9% (110/128) of Gram-positive isolates were correctly identified up to species level. Of species not represented in the database (e.g., Streptococcus suis and Bacillus spp.), 53.1% out of 49 isolates were incorrectly identified as non-related bacterial species. Testing of Gram-positive isolates on Gram-negative panels and vice versa (n = 144) resulted in incorrect identifications for 38.2% of tested isolates. The readability level of the IFU was considered too high for LRS. Inoculation of the panels was favorably evaluated, whereas the visual reading of the panels was considered error-prone. In conclusion, the accuracy of the MicroScan identification panels was excellent for Gram-negative species and good for Gram-positive species. Improvements in stability, robustness, and ease of use have been identified to assure adaptation to LRS constraints.

scholarly journals Evaluating Flinders Technology Associates card for transporting bacterial isolates and retrieval of bacterial DNA after various storage conditions

2020 ◽  
Vol 13 (10) ◽  
pp. 2243-2251
Author(s):  
Azhar G. Shalaby ◽  
Neveen R. Bakry ◽  
Abeer A. E. Mohamed ◽  
Ashraf A. Khalil
Keyword(s):  
Nucleic Acid ◽  
Bacterial Species ◽  
Storage Conditions ◽  
Animal Origin ◽  
Cell Detection ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Bacterial Dna ◽  
Gram Negative ◽  
Fta Cards

Background and Aim: Flinders Technology Associates (FTA) cards simplify sample storage, transport, and extraction by reducing cost and time for diagnosis. This study evaluated the FTA suitability for safe transport and storage of Gram-positive and Gram-negative bacterial cells of animal origin on its liquid culture form and from organ impression smears (tissues) under the same routine condition of microbiological laboratory along with detecting their nucleic acid over different storage conditions. Materials and Methods: Increase in bacterial count from 104 to 107 (colony-forming units/mL) of 78 isolates representing seven bacterial species was applied onto cards. FTA cards were grouped and inoculated by these bacteria and then stored at different conditions of 24-27°C, 4°C, and –20°C for 24 h, for 2 weeks, for 1 and 3 month storage, respectively. Bacteriological examination was done, after which bacterial DNA was identified using specific primers for each bacterial type and detected by polymerase chain reaction (PCR). Results: The total percentage of recovered bacteria from FTA cards was 66.7% at 24-27–C for 24 h, the detection limit was 100% in Gram-positive species, while it was 57.4% in Gram-negative ones. Regarding viable cell detection from organ impression smears, it was successful under the previous conditions. No live bacterial cells were observed by bacteriological isolation rather than only at 24-27°C for 24 h storage. All bacterial DNA were sufficiently confirmed by the PCR technique at different conditions. Conclusion: Overall, the FTA card method was observed to be a valid tool for nucleic acid purification for bacteria of animal origin in the form of culture or organ smears regardless of its Gram type and is used for a short time only 24 h for storage and transport of live bacteria specifically Gram-positive type. Moreover, the bacterial nucleic acid was intact after storage in –20°C for 3 months and was PCR amplifiable.

Comparative evaluation of Assays for Broad Detection of Molecular Resistance Mechanisms in Enterobacterales Isolates

2021 ◽  
Author(s):  
J. N. Brazelton de Cardenas ◽  
C. D. Garner ◽  
Y Su ◽  
L Tang ◽  
R. T. Hayden
Keyword(s):  
Antibiotic Resistance ◽  
Rapid Evolution ◽  
Antibiotic Resistance Genes ◽  
Resistance Mechanisms ◽  
Beta Lactam ◽  
Accurate Identification ◽  
Gram Negative ◽  
Diagnostic Role ◽  
Clinically Significant ◽  
Third Generation Cephalosporins

Rapid detection of antimicrobial resistance in both surveillance and diagnostic settings is still a major challenge for the clinical lab, compounded by the rapid evolution of antibiotic resistance mechanisms. This study compares four methods for the broad detection of antibiotic resistance genes in Enterobacterales isolates: two multiplex PCR assays, (the Streck ARM-D® beta-lactamase kit and the OpGen Acuitas AMR Gene Panel u5.47 (research use only (RUO)), and one microarray assay (the Check-MDR CT103XL assay), with whole genome sequencing as a reference standard. A total of 65 Gram-negative bacterial isolates, from 56 patients, classified by phenotypic AST as showing resistance to beta-lactam antimicrobials (ESBL positive, resistance to third generation cephalosporins or carbapenems), were included in the study. Overall concordance between the molecular assays and sequencing was high. While all three assays had similar performance, the OpGen Acuitas AMR assay had the highest overall percent concordance with sequencing results. The primary differences between the assays tested were the number and diversity of targets, ranging from 9 for Streck to 34 for OpGen. This study shows that commercially available PCR-based assays can provide accurate identification of antimicrobial resistant loci in clinically significant Gram-negative bacteria. Further studies are needed to determine the clinical diagnostic role and potential benefit of such methods.

Sign in / Sign up

Export Citation Format

Share Document