scholarly journals Evolution of antibiotic resistance is linked to any genetic mechanism affecting bacterial duration of carriage

2017 ◽  
Vol 114 (5) ◽  
pp. 1075-1080 ◽  
Author(s):  
Sonja Lehtinen ◽  
François Blanquart ◽  
Nicholas J. Croucher ◽  
Paul Turner ◽  
Marc Lipsitch ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Balancing Selection ◽  
Bacterial Species ◽  
Allelic Diversity ◽  
Antibiotic Consumption ◽  
Resistance Locus ◽  
Partial Explanation ◽  
Fitness Advantage ◽  
Long Duration ◽  
Resistant Strains

Understanding how changes in antibiotic consumption affect the prevalence of antibiotic resistance in bacterial pathogens is important for public health. In a number of bacterial species, includingStreptococcus pneumoniae, the prevalence of resistance has remained relatively stable despite prolonged selection pressure from antibiotics. The evolutionary processes allowing the robust coexistence of antibiotic sensitive and resistant strains are not fully understood. While allelic diversity can be maintained at a locus by direct balancing selection, there is no evidence for such selection acting in the case of resistance. In this work, we propose a mechanism for maintaining coexistence at the resistance locus: linkage to a second locus that is under balancing selection and that modulates the fitness effect of resistance. We show that duration of carriage plays such a role, with long duration of carriage increasing the fitness advantage gained from resistance. We therefore predict that resistance will be more common in strains with a long duration of carriage and that mechanisms maintaining diversity in duration of carriage will also maintain diversity in antibiotic resistance. We test these predictions inS. pneumoniaeand find that the duration of carriage of a serotype is indeed positively correlated with the prevalence of resistance in that serotype. These findings suggest heterogeneity in duration of carriage is a partial explanation for the coexistence of sensitive and resistant strains and that factors determining bacterial duration of carriage will also affect the prevalence of resistance.

scholarly journals Within-host dynamics explain patterns of antibiotic resistance in commensal bacteria

2017 ◽  
Author(s):  
Nicholas G. Davies ◽  
Stefan Flasche ◽  
Mark Jit ◽  
Katherine E. Atkins
Keyword(s):  
Antibiotic Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
Population Level ◽  
Antibiotic Consumption ◽  
Mathematical Framework ◽  
Host Immune Responses ◽  
Resistance Evolution ◽  
Resistant Strains ◽  
The Impact

The spread of antibiotic resistance, a major threat to human health, is poorly understood. Empirically, resistant strains gradually increase in prevalence as antibiotic consumption increases, but current mathematical models predict a sharp transition between full sensitivity and full resistance. In other words, we do not understand what drives persistent coexistence between resistant and sensitive strains of disease-causing bacteria in host populations. Without knowing what drives patterns of resistance, we cannot accurately predict the impact of potential strategies for managing resistance. Here, we show that within-host dynamics—bacterial growth, strain competition, and host immune responses—promote frequency-dependent selection for resistant strains, explaining patterns of resistance at the population level. By capturing these processes in a parsimonious mathematical framework, we resolve a long-standing conflict between theory and observation. Our models capture widespread coexistence for multiple bacteria-drug combinations across 30 European countries and explain associations between carriage prevalence and resistance prevalence among bacterial subtypes. A mechanistic understanding of resistance evolution is needed to accurately forecast the impact and effectiveness of resistance-management strategies.

scholarly journals Dinamic of resistance to antibiotics for the most frequent potential pathogen bacterial isolates in “Dr. V. Babes” Clinical Hospital of Infectious and Tropical Diseases (2000-2015)

2016 ◽  
Vol 19 (2) ◽  
pp. 78-89
Author(s):  
M. Nica ◽  
◽  
T. Biolan ◽  
E. Turcu ◽  
A. Dascălu ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Species ◽  
Test Methods ◽  
Penicillin G ◽  
Diffusion Method ◽  
Internal Quality ◽  
Tropical Diseases ◽  
Dna And Rna ◽  
Potential Pathogen ◽  
Resistant Strains

Objective. Analyzing the dynamycs of global antibiotic resistance of some bacterial species isolated from patients admitted to the „Dr. V. Babes” Hospital for Infectious and Tropical Diseases, between the years 2000 to 2015. Material and methods. Antibiotic resistance profiles of bacteria isolated from inpatients, were identified by the standard diffusion method and MIC values by VITEK2C and E-test methods. (CLSI and EUCAST standards). Screening of carbapenemases – producing isolates were performed by phenotipic methods, and the confirmation by RealTimePCR: “MasterPure™ Complete DNA and RNA Purification Kit” (Epicentre), „Primer Design™ Kit” (blaOXA48; blaKPC, blaNDM, blaVIM)/ LightScanner 32 Instrument/LS32 (Idaho Technology), and GeneXpert. Internal quality control: Staphylococcus aureus ATCC29213, Streptococcus pneumoniae ATCC49619, E. coli ATCC25922, Pseudomonas aeruginosa ATCC27853. Results. The incidence of St. aureus meticilino-rezistent (MRSA) highlights an increase from 12.2% (2002) to 40.4% (2015). In the past 3 years SVB microbiology lab found a sharp increase in the incidence of erytromycin resistant strains of Streptococcus pyogenes. In 2015 we registered 20.3% of macrolide resistant strains. Global resistance to penicillin G for Str. pneumoniae (non-meningeal infections) was 45.3%- 54.5% until 2009, and 2.7% in 2013. Enterococcus faecium strains showed 0% resistance to vancomycin between 2000 and 2012. A significant growth was recorded in 2015 of 11%. Isolation rate of Klebsiella pneumoniae ESBL producing strains has increasewd progressively from 17.6 in 2000 to 57% in 2015. Carbapenems – resistant K. pneumoniae isolated strains were 18,8% in 2015. Carbapenemases types identified by phenotypic and genetic methods where: 35/ Oxa48, 8 KPC and 21/MBL (NDM-1). Resistance to carbapenems recorded an upward trend: 23.9% in 2004 to 37.9% in 2015, and for Acinetobacter baumannii 69%. Conclusions. Antibiotic resistance of bacteria is a major challenge for public healts. Therapeutic solutions are extremely limited.

scholarly journals Antimicrobial Resistant Enterococcus sp. Isolated from Clinical Samples

2020 ◽  
pp. 93-101
Author(s):  
Fawaz Alshammari ◽  
Mohammad Jahoor Alam ◽  
Amir Saeed
Keyword(s):  
Antibiotic Resistance ◽  
Molecular Epidemiology ◽  
Bacterial Species ◽  
Basic Knowledge ◽  
Clinical Samples ◽  
Chain Reaction ◽  
Antimicrobial Susceptibility Test ◽  
Resistant Strains ◽  
Polymerase Chain ◽  
Regional Hospitals

The present study has been targeted towards; investigation of molecular epidemiology and analysis of antibiotic resistance in different bacterial sp. Total 120 new bacterial isolates has been obtained having majority of bacteria Enterococcus sp. from 4 regional hospitals of 92 patients. The antimicrobial susceptibility test has been performed using 18 different antibiotics and resistant strains have been analyzed. Additionally, the isolated strains were tested for antibiotic resistance and polymerase chain reaction (PCR) has been performed for van A and van B genes. In the series of antimicrobial bacterial species Enterococcus sp. has emerged as one of the potential cause to raise the healthcare problems. This study has significant impact on such kind of molecular epidemiology investigations and may be useful in producing the basic knowledge on the local microorganism to refine and resolve the antimicrobial resistance issues faced by hospitals in the world.

scholarly journals Outpatient consumption of antibiotics is linked to antibiotic resistance in Europe: results from the European Surveillance of Antimicrobial Consumption

2005 ◽  
Vol 10 (8) ◽  
Author(s):  
A Johnson
Keyword(s):  
European Union ◽  
Antibiotic Resistance ◽  
Antimicrobial Resistance ◽  
Selective Pressure ◽  
Antibiotic Use ◽  
Antibiotic Consumption ◽  
European Countries ◽  
Antimicrobial Consumption ◽  
Antibiotic Resistant ◽  
Resistant Strains

There is increasing recognition that antibiotic consumption provides a major selective pressure for the emergence and persistence of antibiotic-resistant strains of bacteria. In 2001, a European Union Council Recommendation stated that data should be gathered on antibiotic use and antimicrobial resistance in European countries

scholarly journals The diversity of antibiotic resistance and virulence genes are correlated in human gut and environmental microbiomes

2018 ◽  
Author(s):  
Pedro Escudeiro ◽  
Joël Pothier ◽  
Francisco Dionisio ◽  
Teresa Nogueira
Keyword(s):  
Antibiotic Resistance ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Antibiotic Consumption ◽  
Resistant Bacteria ◽  
Human Populations ◽  
Virulence Determinants ◽  
Human Beings ◽  
Human Gut ◽  
Virulent Strains

AbstractHuman beings have used large amounts of antibiotics, not only in medical contexts but also, for example, as growth factors in agriculture and livestock, resulting in the contamination of the environment. Even when pathogenic bacteria are the targets of antibiotics, hundreds of non-pathogenic bacterial species are affected as well. Therefore, both pathogenic and non-pathogenic bacteria have gradually become resistant to antibiotics. We tested whether there is still co-occurrence of resistance and virulence determinants. We performed a comparative study of environmental and human gut metagenomes issuing from different individuals and from distinct human populations across the world. We found a great diversity of antibiotic resistance determinants (ARd) and virulence factors (VFd) in metagenomes. Importantly there is a correlation between ARd and VFd, even after correcting for protein family richness. In the human gut there are less ARd and VFd than in more diversified environments, and yet correlations between the ARd and VFd are stronger. They can vary from very high in Malawi, where antibiotic consumption is unattended, to non-existent in the uncontacted Amerindians. We conclude that there is co-occurrence of resistance and virulence determinants, suggesting a possible co-selective mechanism. For example, by selecting for resistant bacteria, we may be selecting for more virulent strains as a side effect of antimicrobial therapy.

scholarly journals Metagenomic targets of balancing selection in the human gut

2021 ◽  
Author(s):  
Andrew H. Moeller
Keyword(s):  
Allelic Variation ◽  
Balancing Selection ◽  
Bacterial Species ◽  
Allelic Diversity ◽  
Metagenomic Data ◽  
Adaptive Landscape ◽  
Multidrug Efflux ◽  
Human Gut ◽  
D Values ◽  
Tajima’S D

Bacteria in the human gut contend with numerous fluctuating environmental variables, including bouts of extreme selective agents like antibiotics. Theory predicts that oscillations in the adaptive landscape can impose balancing selection on bacterial populations, leaving characteristic signatures in the sequence variation of functionally significant genomic loci. Despite their potential importance for gut bacterial adaptation, the metagenomic targets of balancing selection have not been identified. Here, I present population genetic evidence that balancing selection maintains allelic diversity in multidrug efflux pumps of multiple predominant bacterial species in the human gut metagenome. Metagenome wide scans of 566,958 core open reading frames (CORFs) from 287 bacterial species represented by 118,617 metagenome assembled genomes (MAGs) indicated that most CORFs have been conserved by purifying selection. However, dozens of CORFs displayed positive Tajima’s D values that deviated significantly from their species’ genomic backgrounds, indicating the action of balancing selection. The AcrB subunit of a multidrug efflux pump (MEP) in Bacteroides dorei displayed the highest Tajima’s D of any CORF, and AcrB and other MEPs from a diversity of bacterial species were significantly enriched among the CORFs with the highest Tajima’s D values. Crystal structures indicated that the regions under balancing selection bind tetracycline and macrolide antibiotics. Other proteins identified as targets of balancing selection included synthases, hydrolases, and ion transporters. Intriguingly, bacterial species experiencing balancing selection were the most abundant in the human gut based on metagenomic data, further suggesting fitness benefits of the allelic variation identified.

scholarly journals Antimicrobial Resistance among Neonates with Bacterial Sepsis and Their Clinical Outcomes in a Tertiary Hospital in Kathmandu Valley, Nepal

2021 ◽  
Vol 6 (2) ◽  
pp. 56
Author(s):  
Bijendra Raj Raghubanshi ◽  
Karuna D. Sagili ◽  
Wai Wai Han ◽  
Henish Shakya ◽  
Priyanka Shrestha ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Neonatal Sepsis ◽  
Bacterial Culture ◽  
Bacterial Species ◽  
Antibiotic Sensitivity ◽  
College Teaching ◽  
Hospital Treatment ◽  
Resistant Bacteria ◽  
Coagulase Negative Staphylococcus ◽  
Cross Sectional

Globally, antibiotic resistance in bacteria isolated from neonatal sepsis is increasing. In this cross-sectional study conducted at a medical college teaching hospital in Nepal, we assessed the antibiotic resistance levels in bacteria cultured from neonates with sepsis and their in-hospital treatment outcomes. We extracted data of neonates with sepsis admitted for in-patient care from June 2018 to December 2019 by reviewing hospital records of the neonatal intensive care unit and microbiology department. A total of 308 neonates with sepsis were admitted of which, blood bacterial culture antibiotic sensitivity reports were available for 298 neonates. Twenty neonates (7%) had bacteriologic culture-confirmed neonatal sepsis. The most common bacterial species isolated were Staphylococcus aureus (8), followed by coagulase-negative Staphylococcus (5). Most of these bacteria were resistant to at least one first-line antibiotic used to manage neonatal sepsis. Overall, there were 7 (2%) deaths among the 308 neonates (none of them from the bacterial culture-positive group), and 53 (17%) neonates had left the hospital against medical advice (LAMA). Improving hospital procedures to isolate bacteria in neonates with sepsis, undertaking measures to prevent the spread of antibiotic-resistant bacteria, and addressing LAMA’s reasons are urgently needed.

scholarly journals Antibiotic Resistance Profile and Biofilm Production of Staphylococcus pseudintermedius Isolated from Dogs in Thailand

2021 ◽  
Vol 14 (6) ◽  
pp. 592
Author(s):  
Pavarish Jantorn ◽  
Hawaree Heemmamad ◽  
Tanawan Soimala ◽  
Saowakon Indoung ◽  
Jongkon Saising ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Meca Gene ◽  
Staphylococcus Pseudintermedius ◽  
Methicillin Resistant ◽  
Antibiotic Resistance Profile ◽  
Biofilm Production ◽  
Southern Thailand ◽  
Life Threatening ◽  
Suitable Treatment ◽  
Resistant Strains

Staphylococcus pseudintermedius is a zoonotic pathogen that can cause life-threatening infections in animals and humans. The study of methicillin-resistant S. pseudintermedius (MRSP) and its ability to produce biofilms is important to select the most suitable treatment. The prevalence and characteristics of S. pseudintermedius isolated from dogs admitted at the Veterinary Teaching Hospital, Prince of Songkla University, Thailand were assessed. Results showed that 28.30% (15/53) of the isolates were MRSP. Amplification of the mecA gene was observed in 93.33% (14/15) MRSP. Methicillin-resistant strains revealed co-resistant patterns against other antibiotics, including chloramphenicol, clindamycin, tetracycline, clarithromycin, ciprofloxacin, and trimethoprim. In this study, all bacterial isolates produced biofilms, while 90.55% of S. pseudintermedius isolates were strong or moderate biofilm producers. Most (45–60%) of the resistant strains were strong biofilm producers, while the correlation between biofilm production and antibiotic resistance was not statistically significant. This is the first study in southern Thailand to investigate the drug-resistant profile of S. pseudintermedius and its ability to form biofilm. The results will contribute to a better understanding of the emergence and prevalence of antimicrobial resistance in S. pseudintermedius.

scholarly journals Pheromone killing of multidrug-resistantEnterococcus faecalisV583 by native commensal strains

2015 ◽  
Vol 112 (23) ◽  
pp. 7273-7278 ◽  
Author(s):  
Michael S. Gilmore ◽  
Marcus Rauch ◽  
Matthew M. Ramsey ◽  
Paul R. Himes ◽  
Sriram Varahan ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Cross Talk ◽  
Metabolic Pathways ◽  
Multidrug Resistant ◽  
Mobile Elements ◽  
Competitive Growth ◽  
Gi Tract ◽  
Subsequent Infection ◽  
Native Flora ◽  
Resistant Strains

Multidrug-resistantEnterococcus faecalispossess numerous mobile elements that encode virulence and antibiotic resistance traits as well as new metabolic pathways, often constituting over one-quarter of the genome. It was of interest to determine how this large accretion of mobile elements affects competitive growth in the gastrointestinal (GI) tract consortium. We unexpectedly observed that the prototype clinical isolate strain V583 was actively killed by GI tract flora, whereas commensal enterococci flourished. It was found that killing of V583 resulted from lethal cross-talk between accumulated mobile elements and that this cross-talk was induced by a heptapeptide pheromone produced by nativeE. faecalispresent in the fecal consortium. These results highlight two important aspects of the evolution of multidrug-resistant enterococci: (i) the accretion of mobile elements inE. faecalisV583 renders it incompatible with commensal strains, and (ii) because of this incompatibility, multidrug-resistant strains sharing features found in V583 cannot coexist with commensal strains. The accumulation of mobile elements in hospital isolates of enterococci can include those that are inherently incompatible with native flora, highlighting the importance of maintaining commensal populations as means of preventing colonization and subsequent infection by multidrug-resistant strains.

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