1
|
Baquero F, Martínez JL, F. Lanza V, Rodríguez-Beltrán J, Galán JC, San Millán A, Cantón R, Coque TM. Evolutionary Pathways and Trajectories in Antibiotic Resistance. Clin Microbiol Rev 2021; 34:e0005019. [PMID: 34190572 PMCID: PMC8404696 DOI: 10.1128/cmr.00050-19] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Evolution is the hallmark of life. Descriptions of the evolution of microorganisms have provided a wealth of information, but knowledge regarding "what happened" has precluded a deeper understanding of "how" evolution has proceeded, as in the case of antimicrobial resistance. The difficulty in answering the "how" question lies in the multihierarchical dimensions of evolutionary processes, nested in complex networks, encompassing all units of selection, from genes to communities and ecosystems. At the simplest ontological level (as resistance genes), evolution proceeds by random (mutation and drift) and directional (natural selection) processes; however, sequential pathways of adaptive variation can occasionally be observed, and under fixed circumstances (particular fitness landscapes), evolution is predictable. At the highest level (such as that of plasmids, clones, species, microbiotas), the systems' degrees of freedom increase dramatically, related to the variable dispersal, fragmentation, relatedness, or coalescence of bacterial populations, depending on heterogeneous and changing niches and selective gradients in complex environments. Evolutionary trajectories of antibiotic resistance find their way in these changing landscapes subjected to random variations, becoming highly entropic and therefore unpredictable. However, experimental, phylogenetic, and ecogenetic analyses reveal preferential frequented paths (highways) where antibiotic resistance flows and propagates, allowing some understanding of evolutionary dynamics, modeling and designing interventions. Studies on antibiotic resistance have an applied aspect in improving individual health, One Health, and Global Health, as well as an academic value for understanding evolution. Most importantly, they have a heuristic significance as a model to reduce the negative influence of anthropogenic effects on the environment.
Collapse
Affiliation(s)
- F. Baquero
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - J. L. Martínez
- National Center for Biotechnology (CNB-CSIC), Madrid, Spain
| | - V. F. Lanza
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
- Central Bioinformatics Unit, Ramón y Cajal Institute for Health Research (IRYCIS), Madrid, Spain
| | - J. Rodríguez-Beltrán
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - J. C. Galán
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - A. San Millán
- National Center for Biotechnology (CNB-CSIC), Madrid, Spain
| | - R. Cantón
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - T. M. Coque
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Network Center for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| |
Collapse
|
2
|
Liu S, Wang P, Wang X, Chen J. Ecological insights into the elevational biogeography of antibiotic resistance genes in a pristine river: Metagenomic analysis along the Yarlung Tsangpo River on the Tibetan Plateau. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117101. [PMID: 33971467 DOI: 10.1016/j.envpol.2021.117101] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 03/22/2021] [Accepted: 04/05/2021] [Indexed: 05/20/2023]
Abstract
Presently, the prevalence of antibiotic resistance genes (ARGs) is regarded as an emerging environmental issue, and many studies have illuminated biogeographical patterns of the antibiotic resistome. However, few studies have investigated elevational biogeography and associated assembly mechanisms of ARGs in natural river systems. Accordingly, in the present study, we used metagenomics approaches to analyze the biogeographical pattern of ARGs along the pristine Yarlung Tsangpo River on the Tibetan Plateau. Our study retrieved the baseline profiles of ARGs in the pristine river and showed that the ARGs were dominated by bacA, which was resistant to bacitracin and represented more than 91% of total ARGs. The diversity and abundance of ARGs in the pristine river were lower than those in the human-impacted area, suggesting that the antibiotic resistome evolved and was promoted in a human-impacted environment. Furthermore, an elevational distance-decay relationship of ARGs was observed along the pristine Yarlung Tsangpo River, which provided strong evidence of ARG dissimilarity under the elevational variation. Elevational gradients could lead to changes in environmental variables and spatial factors, and consequently alter ARG composition. Elevational gradients could influence the assembly processes of ARGs. The deterministic and stochastic assembly processes both played critical roles and equally participated in shaping ARG composition at the watershed scale along the Yarlung Tsangpo River, and with increasing elevational variation along the river, the ecological processes of ARG assembly shifted from deterministic to stochastic. Moreover, abundant and rare ARGs were tentatively separated to investigate the difference and similarity in their distributions. Although abundant and rare ARGs presented similar distance-decay relationships, rare ARGs were more diverse and vulnerable to the dispersal process and mutation. Overall, our study provides valuable ecological insights to profile the large-scale elevational patterns of ARGs in a pristine river system, thereby providing important information for public health and environmental management.
Collapse
Affiliation(s)
- Sheng Liu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Peifang Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
| | - Xun Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| | - Juan Chen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China
| |
Collapse
|
3
|
Tang Q, Huang J, Zhang S, Qin H, Dong Y, Wang C, Li D, Zhou R. Keystone microbes affect the evolution and ecological coexistence of the community via species/strain specificity. J Appl Microbiol 2021; 132:1227-1238. [PMID: 34427980 DOI: 10.1111/jam.15255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/19/2021] [Accepted: 07/27/2021] [Indexed: 02/02/2023]
Abstract
AIM Microbial communities exhibit different diversity and fluctuations in the ecological functions due to time and environmental migration. Despite a long history of research and a plethora of data, the factors determining the biodiversity and stability of ecosystems is still elusive. METHODS AND RESULTS Here, the Chinese Xiaoqu fermentation system was used as a template to explore the mechanism in which the species specificity and strain in the initial phase affect the community structure and metabolites in the subsequent micro-ecosystem. The micro-ecosystem has been applied for hundreds of years, and the main metabolic function can be reproduced and traced. CONCLUSIONS The result proved that Rhizopus spp. is a keystone microbe with a species/strain specificity affecting the trophic interaction niche and function of modules in the complex community through glucose. The fungal community was demonstrated to have a high sealing and stability, while the bacterial community was generally found to change the community structure, physiological function, and interaction relationship, producing strains with connector functions to adapt to fluctuations. SIGNIFICANCE AND IMPACT OF THE STUDY This study shows that the taxonomic level of key microbial strains can be changed to affect the evolution of coexistence and functional realisation of the community.
Collapse
Affiliation(s)
- Qiuxiang Tang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
| | - Jun Huang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
| | - Suyi Zhang
- Luzhoulaojiao Company Limited, Luzhou, China
| | - Hui Qin
- Luzhoulaojiao Company Limited, Luzhou, China
| | - Yi Dong
- Luzhoulaojiao Company Limited, Luzhou, China
| | - Chao Wang
- Luzhoulaojiao Company Limited, Luzhou, China
| | - Delin Li
- Luzhoulaojiao Company Limited, Luzhou, China
| | - Rongqing Zhou
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China.,National Engineering Research Centre of Solid-State Brewing, Luzhou, China
| |
Collapse
|
4
|
Na G, Zhang W, Gao H, Wang C, Li R, Zhao F, Zhang K, Hou C. Occurrence and antibacterial resistance of culturable antibiotic-resistant bacteria in the Fildes Peninsula, Antarctica. MARINE POLLUTION BULLETIN 2021; 162:111829. [PMID: 33243441 DOI: 10.1016/j.marpolbul.2020.111829] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/14/2020] [Accepted: 11/03/2020] [Indexed: 05/12/2023]
Abstract
Quantifying the occurrence of Antarctic antibiotic-resistant bacteria (ARB) is essential for assessing the level of pollution and assessing the "baseline" or background level of ARB in human uninhabited environments. Animal feces, soil, and sediments were sampled from Fildes Peninsula. The abundance of sulfamethazine- and ciprofloxacin-resistance bacteria and antibotic resistance genes (ARGs) within ARB were investigated. The results showed Ciprofloxacin- and Sulfamethazine-resistant bacteria isolated from samples accounted for the highest abundances of 30 CFU/g and 79.8 CFU/g, respectively. The dominant genus of Sulfamethazine-and quinolone-resistance bacteria was Pseudomonas and Arthrobacter, respectively. 106 ARGs were detected from ARB. Strong positive correlations between mobile genetic elements (MGEs) and ARGs were found, what is relatively novel observation that the mechanism is confirmed to also occur in the Antarctic. This study reveals the compositional characteristics of ARGs of strains in Antarctic, providing support for the source of Antarctic antibiotic resistance and drug resistance mechanisms.
Collapse
Affiliation(s)
- Guangshui Na
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China; National Marine Environmental Monitoring Center, Dalian 116023, China; College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572022, China; College of Marine Technology and Environment, Dalian Ocean University, Dalian 116023, China.
| | - Wanli Zhang
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China; National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Hui Gao
- National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Caixia Wang
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China; National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Ruijing Li
- National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Fuqiang Zhao
- National Marine Environmental Monitoring Center, Dalian 116023, China; College of Marine Technology and Environment, Dalian Ocean University, Dalian 116023, China
| | - Keyu Zhang
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China; National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Chao Hou
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China; National Marine Environmental Monitoring Center, Dalian 116023, China
| |
Collapse
|
5
|
The evolution of coexistence from competition in experimental co-cultures of Escherichia coli and Saccharomyces cerevisiae. ISME JOURNAL 2020; 15:746-761. [PMID: 33093620 DOI: 10.1038/s41396-020-00810-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/14/2022]
Abstract
Microbial communities are comprised of many species that coexist on small spatial scales. This is difficult to explain because many interspecies interactions are competitive, and ecological theory predicts that one species will drive the extinction of another species that competes for the same resource. Conversely, evolutionary theory proposes that natural selection can lead to coexistence by driving competing species to use non-overlapping resources. However, evolutionary escape from extinction may be slow compared to the rate of competitive exclusion. Here, we use experimental co-cultures of Escherichia coli and Saccharomyces cerevisiae to study the evolution of coexistence in species that compete for resources. We find that while E. coli usually outcompetes S. cerevisiae in co-culture, a few populations evolved stable coexistence after ~1000 generations of coevolution. We sequenced S. cerevisiae and E. coli populations, identified multi-hit genes, and engineered alleles from these genes into several genetic backgrounds, finding that some mutations modified interactions between E. coli and S. cerevisiae. Together, our data demonstrate that coexistence can evolve, de novo, from intense competition between two species with no history of coevolution.
Collapse
|
6
|
Wang Q, Hamilton PB, Kang F, Zhu X, Zhang Y, Zhao H. Regional-scale investigation for microbial competition-through-environment interactions modulating antibiotic resistance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 734:139341. [PMID: 32473450 DOI: 10.1016/j.scitotenv.2020.139341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/30/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
Originating from a long history of competition between microbes, antibiotic resistance is a serious global health concern. To avoid the risk of antibiotic resistance, tremendous efforts have been directed towards restricting antibiotic consumption worldwide, but to date with limited success. Resistance is governed by multiple pressures from natural and anthropogenic origins which further create problems with control. This study identifies a chain of links from antibiotic resistant genes (ARGs) to microbial communities to environmental pressures in the surface sediments of forty-two lake clusters across the 1000-km Yangtze Basin of China, and attempts to expound on a control pathway for this resistance risk. Results show that eleven of the 670 bacterial families can be classified as antibiotic-resistant or nonresistant communities which antagonize each other. In natural systems, antagonistic competition controls the increase and decrease in ARGs. Superiority of antibiotic-resistant strains initiates a loss in microbial diversity associated with the prevalence of resistance risk. This study shows that, antibiotics shape the evolution of ARGs in resistant communities through a nonlinear role of orientor; other selected pressures serve as a facilitator to enhance the antibiotic resistance through an investigated chain of links. Furthermore, according to tolerances of the classified communities, abiogenetic development through temperature, salinity and Mg were identified and selected for study from seventy lake parameters. Linear feedbacks to selected pressures make the nonresistant communities outcompete the resistant communities, theoretically modulating the risk of antibiotic resistance.
Collapse
Affiliation(s)
- Qian Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Jiangsu 210008, China
| | - Paul B Hamilton
- Canadian Museum of Nature, P. O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada
| | - Fuxing Kang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Jiangsu 210095, China.
| | - Xuezhu Zhu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Jiangsu 210095, China
| | - Yiting Zhang
- College of Public Administration, Nanjing Agricultural University, Jiangsu 210095, China
| | - Haiyan Zhao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Jiangsu 210008, China
| |
Collapse
|
7
|
Reynolds BA, Oli MW, Oli MK. Eco-oncology: Applying ecological principles to understand and manage cancer. Ecol Evol 2020; 10:8538-8553. [PMID: 32884638 PMCID: PMC7452771 DOI: 10.1002/ece3.6590] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 12/25/2022] Open
Abstract
Cancer is a disease of single cells that expresses itself at the population level. The striking similarities between initiation and growth of tumors and dynamics of biological populations, and between metastasis and ecological invasion and community dynamics suggest that oncology can benefit from an ecological perspective to improve our understanding of cancer biology. Tumors can be viewed as complex, adaptive, and evolving systems as they are spatially and temporally heterogeneous, continually interacting with each other and with the microenvironment and evolving to increase the fitness of the cancer cells. We argue that an eco-evolutionary perspective is essential to understand cancer biology better. Furthermore, we suggest that ecologically informed therapeutic approaches that combine standard of care treatments with strategies aimed at decreasing the evolutionary potential and fitness of neoplastic cells, such as disrupting cell-to-cell communication and cooperation, and preventing successful colonization of distant organs by migrating cancer cells, may be effective in managing cancer as a chronic condition.
Collapse
Affiliation(s)
- Brent A. Reynolds
- Department of NeurosurgeryCollege of MedicineUniversity of FloridaGainesvilleFLUSA
| | - Monika W. Oli
- Department of Microbiology and Cell ScienceInstitute of Food and Agricultural SciencesUniversity of FloridaGainesvilleFLUSA
| | - Madan K. Oli
- Department of Wildlife Ecology and ConservationInstitute of Food and Agricultural SciencesUniversity of FloridaGainesvilleFLUSA
| |
Collapse
|
8
|
Mittal RP, Rana A, Jaitak V. Essential Oils: An Impending Substitute of Synthetic Antimicrobial Agents to Overcome Antimicrobial Resistance. Curr Drug Targets 2020; 20:605-624. [PMID: 30378496 DOI: 10.2174/1389450119666181031122917] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/09/2018] [Accepted: 10/22/2018] [Indexed: 01/21/2023]
Abstract
Antimicrobial resistance (AMR) is an emerging problem in the world that has a significant impact on our society. AMR made conventional drugs futile against microorganisms and diseases untreatable. Plant-derived medicines are considered to be safe alternatives as compared to synthetic drugs. Active ingredients and the mixtures of these natural medicines have been used for centuries, due to their easy availability, low cost, and negligible side effects. Essential oils (EOs) are the secondary metabolites that are produced by aromatic plants to protect them from microorganisms. However, these EOs and their constituents have shown good fighting potential against drug-resistant pathogens. These oils have been proved extremely effective antimicrobial agents in comparison to antibiotics. Also, the combination of synthetic drugs with EOs or their components improve their efficacy. So, EOs can be established as an alternative to synthetic antimicrobial agents to eradicate tough form of infectious microorganisms. EO's can interact with multiple target sites, like the destruction of cytoplasm membrane or inhibition of protein synthesis and efflux pump, etc. The purpose of this review is to provide information about the antimicrobial activity of EOs attained from different plants, their combination with synthetic antimicrobials. In addition, mechanism of antimicrobial activity of several EOs and their constituents was reported.
Collapse
Affiliation(s)
- Rajinder Pal Mittal
- Laboratory of Natural Product Chemistry, Department of Pharmaceutical Sciences and Natural Products, Central University of Punjab, Bathinda, Punjab, 151001, India
| | - Abhilash Rana
- Laboratory of Natural Product Chemistry, Department of Pharmaceutical Sciences and Natural Products, Central University of Punjab, Bathinda, Punjab, 151001, India
| | - Vikas Jaitak
- Laboratory of Natural Product Chemistry, Department of Pharmaceutical Sciences and Natural Products, Central University of Punjab, Bathinda, Punjab, 151001, India
| |
Collapse
|
9
|
Ouyang Y, Li J, Peng Y, Huang Z, Ren Q, Lu J. The Role and Mechanism of Thiol-Dependent Antioxidant System in Bacterial Drug Susceptibility and Resistance. Curr Med Chem 2020; 27:1940-1954. [DOI: 10.2174/0929867326666190524125232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 01/24/2019] [Accepted: 02/21/2019] [Indexed: 12/16/2022]
Abstract
Antibiotics play an irreplaceable role in the prevention and treatment of bacterial infection
diseases. However, because of the improper use of antibiotics, bacterial resistance emerges as a major
challenge of public health all over the world. The small thiol molecules such as glutathione can directly
react and conjugate with some antibiotics, which thus contribute to drug susceptibility and resistance.
Recently, accumulating evidence shows that there is a close link between the antibacterial activities of
some antibiotics and Reactive Oxygen Species (ROS). Thioredoxin and glutathione systems are two
main cellular disulfide reductase systems maintaining cellular ROS level. Therefore, these two thioldependent
antioxidant systems may affect the antibiotic susceptibility and resistance. Microorganisms
are equipped with different thiol-dependent antioxidant systems, which make the role of thioldependent
antioxidant systems in antibiotic susceptibility and resistance is different in various bacteria.
Here we will focus on the review on the advances of the effects of thiol-dependent antioxidant system
in the bacterial antibiotic susceptibility and resistance.
Collapse
Affiliation(s)
- Yanfang Ouyang
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Jing Li
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Yi Peng
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Zhijun Huang
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Qiao Ren
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Jun Lu
- Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education (Southwest University), College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| |
Collapse
|
10
|
Goldstein E, Lipsitch M. The relation between prescribing of different antibiotics and rates of mortality with sepsis in US adults. BMC Infect Dis 2020; 20:169. [PMID: 32087679 PMCID: PMC7036250 DOI: 10.1186/s12879-020-4901-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 02/18/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Antibiotic use contributes to the rates of sepsis and the associated mortality, particularly through lack of clearance of resistant infections following antibiotic treatment. At the same time, there is limited information on the effects of prescribing of some antibiotics vs. others on subsequent sepsis and sepsis-related mortality. METHODS We used a multivariable mixed-effects model to relate state-specific rates of outpatient prescribing overall for oral fluoroquinolones, penicillins, macrolides, and cephalosporins between 2014 and 2015 to state-specific rates of mortality with sepsis (ICD-10 codes A40-41 present as either underlying or contributing causes of death on a death certificate) in different age groups of US adults between 2014 and 2015, adjusting for additional covariates and random effects associated with the ten US Health and Human Services (HHS) regions. RESULTS Increase in the rate of prescribing of oral penicillins by 1 annual dose per 1000 state residents was associated with increases in annual rates of mortality with sepsis of 0.95 (95% CI (0.02,1.88)) per 100,000 persons aged 75-84y, and of 2.97 (0.72,5.22) per 100,000 persons aged 85 + y. Additionally, the percent of individuals aged 50-64y lacking health insurance, as well as the percent of individuals aged 65-84y who are African-American were associated with rates of mortality with sepsis in the corresponding age groups. CONCLUSIONS Our results suggest that prescribing of penicillins is associated with rates of mortality with sepsis in older US adults. Those results, as well as the related epidemiological data suggest that replacement of certain antibiotics, particularly penicillins in the treatment of different syndromes should be considered with the aim of reducing the rates of severe outcomes, including mortality related to bacterial infections.
Collapse
Affiliation(s)
- Edward Goldstein
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA.
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA
- Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA
| |
Collapse
|
11
|
Goldstein E, Olesen SW, Karaca Z, Steiner CA, Viboud C, Lipsitch M. Levels of outpatient prescribing for four major antibiotic classes and rates of septicemia hospitalization in adults in different US states - a statistical analysis. BMC Public Health 2019; 19:1138. [PMID: 31426780 PMCID: PMC6701127 DOI: 10.1186/s12889-019-7431-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Rates of sepsis/septicemia hospitalization in the US have risen significantly during recent years. Antibiotic resistance and use may contribute to those rates through various mechanisms, including lack of clearance of resistant infections following antibiotic treatment, with some of those infections subsequently devolving into sepsis. At the same time, there is limited information on the effect of prescribing of certain antibiotics vs. others on the rates of septicemia and sepsis-related hospitalizations and mortality. METHODS We used multivariable linear regression to relate state-specific rates of outpatient prescribing overall for oral fluoroquinolones, penicillins, macrolides, and cephalosporins between 2011 and 2012 to state-specific rates of septicemia hospitalization (ICD-9 codes 038.xx present anywhere on a discharge diagnosis) in each of the following age groups of adults: (18-49y, 50-64y, 65-74y, 75-84y, 85 + y) reported to the Healthcare Cost and Utilization Project (HCUP) between 2011 and 2012, adjusting for additional covariates, and random effects associated with the ten US Health and Human Services (HHS) regions. RESULTS Increase in the rate of prescribing of oral penicillins by 1 annual dose per 1000 state residents was associated with increases in annual septicemia hospitalization rates of 0.19 (95% CI (0.02,0.37)) per 10,000 persons aged 50-64y, of 0.48(0.12,0.84) per 10,000 persons aged 65-74y, and of 0.81(0.17,1.40) per 10,000 persons aged 74-84y. Increase by 1 in the percent of African Americans among state residents in a given age group was associated with increases in annual septicemia hospitalization rates of 2.3(0.32,4.2) per 10,000 persons aged 75-84y, and of 5.3(1.1,9.5) per 10,000 persons aged over 85y. Average minimal daily temperature was positively associated with septicemia hospitalization rates in persons aged 18-49y, 50-64y, 75-84y and over 85y. CONCLUSIONS Our results suggest positive associations between the rates of prescribing for penicillins and the rates of hospitalization with septicemia in US adults aged 50-84y. Further studies are needed to better understand the potential effect of antibiotic replacement in the treatment of various syndromes, including the potential impact of the recent US FDA guidelines on restriction of fluoroquinolone use, as well as the potential effect of changes in the practices for prescribing of penicillins on the rates of sepsis-related hospitalization and mortality.
Collapse
Affiliation(s)
- Edward Goldstein
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, 677 Huntington Ave, Kresge Room 506, Boston, MA 02115 USA
| | - Scott W. Olesen
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, 677 Huntington Ave, Kresge Room 506, Boston, MA 02115 USA
| | - Zeynal Karaca
- U.S. Department of Health & Human Services, Agency for HealthCare Research and Quality, Rockville, MD 20850 USA
| | - Claudia A. Steiner
- Institute for Health Research, Kaiser Permanente Colorado, Denver, CO 80231 USA
| | - Cecile Viboud
- Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD 20892 USA
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, 677 Huntington Ave, Kresge Room 506, Boston, MA 02115 USA
- Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA 02115 USA
| |
Collapse
|
12
|
Influence of the T to S mutation at the STMK motif on antibiotic resistance of penicillin binding protein 1A: A comprehensive computational study. J Mol Graph Model 2018; 87:185-191. [PMID: 30553158 DOI: 10.1016/j.jmgm.2018.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/13/2018] [Accepted: 12/04/2018] [Indexed: 11/21/2022]
Abstract
The emergence of antibiotic resistance has attracted the attention of scientists and scientific circles over the decades. β-Lactam antibiotics resistance is a worldwide therapeutic challenge in bacterial infections, mediated through several mechanisms of which mutations in Penicillin Binding Proteins (PBPs) are an important issue, making critical therapeutic problems in the human population. Accordingly, investigating the dynamic structures of mutant variants could result in a profound understanding of such a specific resistance. Therefore, this work investigated structural properties sampled by all-atom molecular dynamics (MD) simulations, umbrella sampling, and binding free energy calculations for both a wild-type and a cefotaxime-resistant T to S mutant of PBP1A. The T to S mutation significantly reduces the binding affinity of cefotaxime (a frequently clinically-administrated β-lactam antibiotic) as the PBP1A inhibitor. In the conventional MD simulations presented here, more fluctuations of the mutant's active site cleft margins were detected. The cleft of the mutant protein also opened remarkably more than the wild-type's cleft and displayed more flexibility. Thus, our findings have shown that flexibility of cleft margins of the active site in the mutant PBP1A immediately results in the catalytic cleft opening. In addition, binding free energy calculation suggests that reducing hydrophobic contacts and increasing the polar contribution in the binding energy may play an important role in cefotaxime resistance.
Collapse
|
13
|
Shefferson RP, Mason CM, Kellett KM, Goolsby EW, Coughlin E, Flynn RW. The evolutionary impacts of conservation actions. POPUL ECOL 2018. [DOI: 10.1007/s10144-018-0614-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
14
|
Farrell FD, Gralka M, Hallatschek O, Waclaw B. Mechanical interactions in bacterial colonies and the surfing probability of beneficial mutations. J R Soc Interface 2018; 14:rsif.2017.0073. [PMID: 28592660 PMCID: PMC5493792 DOI: 10.1098/rsif.2017.0073] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/12/2017] [Indexed: 11/12/2022] Open
Abstract
Bacterial conglomerates such as biofilms and microcolonies are ubiquitous in nature and play an important role in industry and medicine. In contrast to well-mixed cultures routinely used in microbial research, bacteria in a microcolony interact mechanically with one another and with the substrate to which they are attached. Here, we use a computer model of a microbial colony of rod-shaped cells to investigate how physical interactions between cells determine their motion in the colony and how this affects biological evolution. We show that the probability that a faster-growing mutant ‘surfs’ at the colony's frontier and creates a macroscopic sector depends on physical properties of cells (shape, elasticity and friction). Although all these factors contribute to the surfing probability in seemingly different ways, their effects can be summarized by two summary statistics that characterize the front roughness and cell alignment. Our predictions are confirmed by experiments in which we measure the surfing probability for colonies of different front roughness. Our results show that physical interactions between bacterial cells play an important role in biological evolution of new traits, and suggest that these interactions may be relevant to processes such as de novo evolution of antibiotic resistance.
Collapse
Affiliation(s)
- Fred D Farrell
- Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Matti Gralka
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Oskar Hallatschek
- Department of Physics, University of California, Berkeley, CA 94720, USA.,Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Bartlomiej Waclaw
- School of Physics and Astronomy, University of Edinburgh, JCMB, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK .,Centre for Synthetic and Systems Biology, University of Edinburgh, CH Waddington Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| |
Collapse
|
15
|
Abstract
The continual emergence of new pathogens and the increased spread of antibiotic resistance in bacterial populations remind us that microbes are living entities that evolve at rates that impact public health interventions. Following the historical thread of the works of Pasteur and Darwin shows how reconciling clinical microbiology, ecology, and evolution can be instrumental to understanding pathology, developing new therapies, and prolonging the efficiency of existing ones.
Collapse
Affiliation(s)
- Samuel Alizon
- Laboratoire MIVEGEC (UMR CNRS 5290, UR IRD 224, UM), Montpellier, France
- * E-mail:
| | | |
Collapse
|
16
|
Rudman SM, Kreitzman M, Chan KMA, Schluter D. Evosystem Services: Rapid Evolution and the Provision of Ecosystem Services. Trends Ecol Evol 2017; 32:403-415. [PMID: 28336183 DOI: 10.1016/j.tree.2017.02.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 12/21/2022]
Abstract
Evolution is recognized as the source of all organisms, and hence many ecosystem services. However, the role that contemporary evolution might play in maintaining and enhancing specific ecosystem services has largely been overlooked. Recent advances at the interface of ecology and evolution have demonstrated how contemporary evolution can shape ecological communities and ecosystem functions. We propose a definition and quantitative criteria to study how rapid evolution affects ecosystem services (here termed contemporary evosystem services) and present plausible scenarios where such services might exist. We advocate for the direct measurement of contemporary evosystem services to improve understanding of how changing environments will alter resource availability and human well-being, and highlight the potential utility of managing rapid evolution for future ecosystem services.
Collapse
Affiliation(s)
- Seth M Rudman
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, BC V6T 1Z4, Canada.
| | - Maayan Kreitzman
- Institute for Resources, Environment, and Sustainability, University of British Columbia, 429-2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Kai M A Chan
- Institute for Resources, Environment, and Sustainability, University of British Columbia, 429-2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Dolph Schluter
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, BC V6T 1Z4, Canada
| |
Collapse
|
17
|
Liggett LA, DeGregori J. Changing mutational and adaptive landscapes and the genesis of cancer. Biochim Biophys Acta Rev Cancer 2017; 1867:84-94. [PMID: 28167050 DOI: 10.1016/j.bbcan.2017.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 01/27/2017] [Accepted: 01/28/2017] [Indexed: 12/31/2022]
Abstract
By the time the process of oncogenesis has produced an advanced cancer, tumor cells have undergone extensive evolution. The cellular phenotypes resulting from this evolution have been well studied, and include accelerated growth rates, apoptosis resistance, immortality, invasiveness, and immune evasion. Yet with all of our current knowledge of tumor biology, the details of early oncogenesis have been difficult to observe and understand. Where different oncogenic mutations may work together to enhance the survival of a tumor cell, in isolation they are often pro-apoptotic, pro-differentiative or pro-senescent, and therefore often, somewhat paradoxically, disadvantageous to a cell. It is also becoming clear that somatic mutations, including those in known oncogenic drivers, are common in tissues starting at a young age. These observations raise the question: how do we largely avoid cancer for most of our lives? Here we propose that evolutionary forces can help explain this paradox. As humans and other organisms age or experience external insults such as radiation or smoking, the structure and function of tissues progressively degrade, resulting in altered stem cell niche microenvironments. As tissue integrity declines, it becomes less capable of supporting and maintaining resident stem cells. These stem cells then find themselves in a microenvironment to which they are poorly adapted, providing a competitive advantage to those cells that can restore their functionality and fitness through mutations or epigenetic changes. The resulting oncogenic clonal expansions then increase the odds of further cancer progression. Understanding how the causes of cancer, such as aging or smoking, affect tissue microenvironments to control the impact of mutations on somatic cell fitness can help reconcile the discrepancy between marked mutation accumulation starting early in life and the somatic evolution that leads to cancer at advanced ages or following carcinogenic insults. This article is part of a Special Issue entitled: Evolutionary principles - heterogeneity in cancer?, edited by Dr. Robert A. Gatenby.
Collapse
Affiliation(s)
- L Alexander Liggett
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, United States
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, United States; Integrated Department of Immunology, University of Colorado School of Medicine, Aurora, CO 80045, United States; Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, United States; Department of Medicine, Section of Hematology, University of Colorado School of Medicine, Aurora, CO 80045, United States.
| |
Collapse
|
18
|
Impact on Bacterial Resistance of Therapeutically Nonequivalent Generics: The Case of Piperacillin-Tazobactam. PLoS One 2016; 11:e0155806. [PMID: 27191163 PMCID: PMC4871539 DOI: 10.1371/journal.pone.0155806] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/04/2016] [Indexed: 11/19/2022] Open
Abstract
Previous studies have demonstrated that pharmaceutical equivalence and pharmacokinetic equivalence of generic antibiotics are necessary but not sufficient conditions to guarantee therapeutic equivalence (better called pharmacodynamic equivalence). In addition, there is scientific evidence suggesting a direct link between pharmacodynamic nonequivalence of generic vancomycin and promotion of resistance in Staphylococcus aureus. To find out if even subtle deviations from the expected pharmacodynamic behavior with respect to the innovator could favor resistance, we studied a generic product of piperacillin-tazobactam characterized by pharmaceutical and pharmacokinetic equivalence but a faulty fit of Hill's Emax sigmoid model that could be interpreted as pharmacodynamic nonequivalence. We determined the impact in vivo of this generic product on the resistance of a mixed Escherichia coli population composed of ∼99% susceptible cells (ATCC 35218 strain) and a ∼1% isogenic resistant subpopulation that overproduces TEM-1 β-lactamase. After only 24 hours of treatment in the neutropenic murine thigh infection model, the generic amplified the resistant subpopulation up to 20-times compared with the innovator, following an inverted-U dose-response relationship. These findings highlight the critical role of therapeutic nonequivalence of generic antibiotics as a key factor contributing to the global problem of bacterial resistance.
Collapse
|
19
|
Magnussen MD, Gaini S, Gislason H, Kristinsson KG. Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands. APMIS 2016; 124:327-32. [PMID: 26833774 DOI: 10.1111/apm.12513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 12/10/2015] [Indexed: 12/01/2022]
Abstract
The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0-7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37-10%, p-value = 0.006 < 0.05) and differed significantly between age groups (p-value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones.
Collapse
Affiliation(s)
- Marita D Magnussen
- Microbiological Department, Faroese Food- and Veterinary Authority, Tórshavn, Faroe Islands.,Medical Faculty, University of Iceland, Reykjavík, Iceland
| | - Shahin Gaini
- Department of Internal Medicine & Research Unit of the Medical Department, National Hospital of the Faroe Islands, Queen Alexandrines Teaching Hospital, Tórshavn, Faroe Islands.,Department of Infectious Diseases, Odense University Hospital, Odense, Denmark.,University of Southern Denmark, Odense, Denmark
| | - Hannes Gislason
- Faculty of Science and Technology, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Karl G Kristinsson
- Medical Faculty, University of Iceland, Reykjavík, Iceland.,Department of Clinical Microbiology, Landspitali University Hospital, Reykjavík, Iceland
| |
Collapse
|
20
|
Kim TW, Joung Y, Han JH, Jung W, Kim SB. Antibiotic resistance among aquatic bacteria in natural freshwater environments of Korea. JOURNAL OF WATER AND HEALTH 2015; 13:1085-1097. [PMID: 26608770 DOI: 10.2166/wh.2015.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The taxonomic diversity and antibiotic resistance among freshwater bacterial communities in the major water bodies of Korea was examined using 437 penicillin-resistant, and 110 tetracycline-resistant bacterial isolates. Based on 16S rRNA gene sequence analysis, most isolates were assigned to Proteobacteria, which was then followed by Bacteroidetes. Strains of Aeromonas were found as the most abundant penicillin-resistant populations, whereas those affiliated to diverse species including enteric groups were found as the most abundant tetracycline-resistant populations. Most strains exhibited multiple antibiotic resistance, and all tested strains were resistant to penicillin and hygromycin. High levels of resistance were observed for antibiotics acting on cell wall synthesis, whereas low levels were for those acting on DNA replication or transcription in general. It is apparent from this study that penicillin resistance is widespread among environmental bacteria, although the antibiotic has been generally non-detectable in the environment. It is also likely from the taxonomic composition of the resistant communities that various sources including terrestrial animals and humans may contribute to antibiotic resistance in the freshwater environment.
Collapse
Affiliation(s)
- Tae Woon Kim
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, 99 Daehak-Ro, Yuseong, Daejeon 305-764, Republic of Korea E-mail:
| | - Yochan Joung
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, 99 Daehak-Ro, Yuseong, Daejeon 305-764, Republic of Korea E-mail:
| | - Ji-Hye Han
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, 99 Daehak-Ro, Yuseong, Daejeon 305-764, Republic of Korea E-mail:
| | - Wonwha Jung
- National Institute of Environmental Research, Incheon, Korea
| | - Seung Bum Kim
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, 99 Daehak-Ro, Yuseong, Daejeon 305-764, Republic of Korea E-mail:
| |
Collapse
|
21
|
Czekalski N, Sigdel R, Birtel J, Matthews B, Bürgmann H. Does human activity impact the natural antibiotic resistance background? Abundance of antibiotic resistance genes in 21 Swiss lakes. ENVIRONMENT INTERNATIONAL 2015; 81:45-55. [PMID: 25913323 DOI: 10.1016/j.envint.2015.04.005] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Revised: 03/30/2015] [Accepted: 04/10/2015] [Indexed: 05/06/2023]
Abstract
Antibiotic resistance genes (ARGs) are emerging environmental contaminants, known to be continuously discharged into the aquatic environment via human and animal waste. Freshwater aquatic environments represent potential reservoirs for ARG and potentially allow sewage-derived ARG to persist and spread in the environment. This may create increased opportunities for an eventual contact with, and gene transfer to, human and animal pathogens via the food chain or drinking water. However, assessment of this risk requires a better understanding of the level and variability of the natural resistance background and the extent of the human impact. We have analyzed water samples from 21 Swiss lakes, taken at sampling points that were not under the direct influence of local contamination sources and analyzed the relative abundance of ARG using quantitative real-time PCR. Copy numbers of genes mediating resistance to three different broad-spectrum antibiotic classes (sulfonamides: sul1, sul2, tetracyclines: tet(B), tet(M), tet(W) and fluoroquinolones: qnrA) were normalized to copy numbers of bacterial 16S rRNA genes. We used multiple linear regression to assess if ARG abundance is related to human activities in the catchment, microbial community composition and the eutrophication status of the lakes. Sul genes were detected in all sampled lakes, whereas only four lakes contained quantifiable numbers of tet genes, and qnrA remained below detection in all lakes. Our data indicate higher abundance of sul1 in lakes with increasing number and capacity of wastewater treatment plants (WWTPs) in the catchment. sul2 abundance was rather related to long water residence times and eutrophication status. Our study demonstrates the potential of freshwater lakes to preserve antibiotic resistance genes, and provides a reference for ARG abundance from lake systems with low human impact as a baseline for assessing ARG contamination in lake water.
Collapse
Affiliation(s)
- Nadine Czekalski
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Surface Waters - Research and Management, 6047 Kastanienbaum, Switzerland
| | - Radhika Sigdel
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Surface Waters - Research and Management, 6047 Kastanienbaum, Switzerland
| | - Julia Birtel
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Aquatic Ecology, 6047 Kastanienbaum, Switzerland
| | - Blake Matthews
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Aquatic Ecology, 6047 Kastanienbaum, Switzerland
| | - Helmut Bürgmann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Surface Waters - Research and Management, 6047 Kastanienbaum, Switzerland.
| |
Collapse
|
22
|
Tam HK, Wong CMVL, Yong ST, Blamey J, González M. Multiple-antibiotic-resistant bacteria from the maritime Antarctic. Polar Biol 2015. [DOI: 10.1007/s00300-015-1671-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
23
|
AbdelRahim KAA, Hassanein AM, Abd El Azeiz HAEH. Prevalence, plasmids and antibiotic resistance correlation of enteric bacteria in different drinking water resources in sohag, egypt. Jundishapur J Microbiol 2015; 8:e18648. [PMID: 25763135 PMCID: PMC4344770 DOI: 10.5812/jjm.18648] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 06/29/2014] [Accepted: 08/04/2014] [Indexed: 12/05/2022] Open
Abstract
Background: One of the major health causing problems is contamination of drinking water sources with human pathogenic bacteria. Enteric bacteria such as Shigella, Salmonella and Escherichia coli are most enteric bacteria causing serious health problems. Occurrence of such bacteria infection, which may resist antibiotics, increases the seriousness of problem. Objectives: The aim of this study was to examine the prevalence of some enteric bacteria (Shigella, Salmonella and E. coli) in addition to Pseudomonas. The antibiotic susceptibility of these bacteria was also tested, in addition to assessing plasmid(s) roles in supposed resistance. MRSA genes in non-staphylococci were clarified. Materials and Methods: Water samples were collected from different drinking sources (Nile, ground water) and treated tap water. Selective media were used to isolate enteric bacteria and Pseudomonas. These bacteria were identified, counted and examined for its susceptibility against 10 antibiotics. The plasmids were screened in these strains. MRSA genes were also examined using PCR. Results: Thirty-two bacterial strains were isolated from Nile and ground water and identified as S. flexneri, S. sonnei, S. serovar Newport, Pseudomonas aeruginosa and E. coli strains according to standard methods. According to antibiotic susceptibility test, 81% of strains were resistant to Cefepime, whereas 93.75% were sensitive to Ciprofloxacin. Correlation analysis between plasmids profiles and antibiotics sensitivities showed that 50% of the total strains had plasmids. These strains showed resistance to 50% of the used antibiotics (as average value); whereas, the plasmids free strains (50%) were resistant to 48.7% of the antibiotics. No distinct correlation between plasmids and antibiotic resistance in some strains could be concluded in this study. No MRSA gene was detected among these non-staphylococci strains. No bacteria were isolated from treated tap water. Conclusions: Thirty-three bacterial strains; 10 strains of E. coli, 10 strains of S. flexneri, 3 strains S. sonnei, 2 strains of S. serovar Newport, and 7 strains of P. aeruginosa, were isolated and identified from Nile water and ground water in Sohag governorate. The prevalence of enteric bacteria in water sources in studying area was considerable. No clear or distinct correlation could be concluded between plasmids and antibiotic resistance. No MRSA gene was detected in these non-staphylococci strains, and no pathogenic bacteria were isolated from treated tap water. The hygiene procedures in the studying area seem to be adequate, despite the failure to maintain water sources form sewage pollution.
Collapse
Affiliation(s)
- Khalid Abdalla Ali AbdelRahim
- Department of Botany and Microbiology, King Saud University, Riyadh, Saudi Arabia
- Department of Botany, Sohag University, Sohag, Egypt
- Corresponding author: Khalid Abdalla Ali Abdel Rahim, Department of Botany and Microbiology, King Saud University, P. O. Box: 2455, Riyadh, Saudi Arabia. Tel: +96-6114675818, Fax: +96-6114675833, E-mail:
| | | | | |
Collapse
|
24
|
Blows MW, McGuigan K. The distribution of genetic variance across phenotypic space and the response to selection. Mol Ecol 2014; 24:2056-72. [DOI: 10.1111/mec.13023] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/20/2014] [Accepted: 11/25/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Mark W. Blows
- School of Biological Sciences; University of Queensland; St Lucia Qld 4072 Australia
| | - Katrina McGuigan
- School of Biological Sciences; University of Queensland; St Lucia Qld 4072 Australia
| |
Collapse
|
25
|
Wastewater irrigation increases the abundance of potentially harmful gammaproteobacteria in soils in Mezquital Valley, Mexico. Appl Environ Microbiol 2014; 80:5282-91. [PMID: 24951788 DOI: 10.1128/aem.01295-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Wastewater contains large amounts of pharmaceuticals, pathogens, and antimicrobial resistance determinants. Only a little is known about the dissemination of resistance determinants and changes in soil microbial communities affected by wastewater irrigation. Community DNAs from Mezquital Valley soils under irrigation with untreated wastewater for 0 to 100 years were analyzed by quantitative real-time PCR for the presence of sul genes, encoding resistance to sulfonamides. Amplicon sequencing of bacterial 16S rRNA genes from community DNAs from soils irrigated for 0, 8, 10, 85, and 100 years was performed and revealed a 14% increase of the relative abundance of Proteobacteria in rainy season soils and a 26.7% increase in dry season soils for soils irrigated for 100 years with wastewater. In particular, Gammaproteobacteria, including potential pathogens, such as Pseudomonas, Stenotrophomonas, and Acinetobacter spp., were found in wastewater-irrigated fields. 16S rRNA gene sequencing of 96 isolates from soils irrigated with wastewater for 100 years (48 from dry and 48 from rainy season soils) revealed that 46% were affiliated with the Gammaproteobacteria (mainly potentially pathogenic Stenotrophomonas strains) and 50% with the Bacilli, whereas all 96 isolates from rain-fed soils (48 from dry and 48 from rainy season soils) were affiliated with the Bacilli. Up to six types of antibiotic resistance were found in isolates from wastewater-irrigated soils; sulfamethoxazole resistance was the most abundant (33.3% of the isolates), followed by oxacillin resistance (21.9% of the isolates). In summary, we detected an increase of potentially harmful bacteria and a larger incidence of resistance determinants in wastewater-irrigated soils, which might result in health risks for farm workers and consumers of wastewater-irrigated crops.
Collapse
|
26
|
Genetic validation of aminoacyl-tRNA synthetases as drug targets in Trypanosoma brucei. EUKARYOTIC CELL 2014; 13:504-16. [PMID: 24562907 DOI: 10.1128/ec.00017-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Human African trypanosomiasis (HAT) is an important public health threat in sub-Saharan Africa. Current drugs are unsatisfactory, and new drugs are being sought. Few validated enzyme targets are available to support drug discovery efforts, so our goal was to obtain essentiality data on genes with proven utility as drug targets. Aminoacyl-tRNA synthetases (aaRSs) are known drug targets for bacterial and fungal pathogens and are required for protein synthesis. Here we survey the essentiality of eight Trypanosoma brucei aaRSs by RNA interference (RNAi) gene expression knockdown, covering an enzyme from each major aaRS class: valyl-tRNA synthetase (ValRS) (class Ia), tryptophanyl-tRNA synthetase (TrpRS-1) (class Ib), arginyl-tRNA synthetase (ArgRS) (class Ic), glutamyl-tRNA synthetase (GluRS) (class 1c), threonyl-tRNA synthetase (ThrRS) (class IIa), asparaginyl-tRNA synthetase (AsnRS) (class IIb), and phenylalanyl-tRNA synthetase (α and β) (PheRS) (class IIc). Knockdown of mRNA encoding these enzymes in T. brucei mammalian stage parasites showed that all were essential for parasite growth and survival in vitro. The reduced expression resulted in growth, morphological, cell cycle, and DNA content abnormalities. ThrRS was characterized in greater detail, showing that the purified recombinant enzyme displayed ThrRS activity and that the protein localized to both the cytosol and mitochondrion. Borrelidin, a known inhibitor of ThrRS, was an inhibitor of T. brucei ThrRS and showed antitrypanosomal activity. The data show that aaRSs are essential for T. brucei survival and are likely to be excellent targets for drug discovery efforts.
Collapse
|
27
|
Cohen BE. Functional linkage between genes that regulate osmotic stress responses and multidrug resistance transporters: challenges and opportunities for antibiotic discovery. Antimicrob Agents Chemother 2013; 58:640-6. [PMID: 24295980 PMCID: PMC3910827 DOI: 10.1128/aac.02095-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
All cells need to protect themselves against the osmotic challenges of their environment by maintaining low permeability to ions across their cell membranes. This is a basic principle of cellular function, which is reflected in the interactions among ion transport and drug efflux genes that have arisen during cellular evolution. Thus, upon exposure to pore-forming antibiotics such as amphotericin B (AmB) or daptomycin (Dap), sensitive cells overexpress common resistance genes to protect themselves from added osmotic challenges. These genes share pathway interactions with the various types of multidrug resistance (MDR) transporter genes, which both preserve the native lipid membrane composition and at the same time eliminate disruptive hydrophobic molecules that partition excessively within the lipid bilayer. An increased understanding of the relationships between the genes (and their products) that regulate osmotic stress responses and MDR transporters will help to identify novel strategies and targets to overcome the current stalemate in drug discovery.
Collapse
Affiliation(s)
- B Eleazar Cohen
- National Institute of Allergy and Infectious Diseases, Division of Extramural Activities, Bethesda, Maryland, USA
| |
Collapse
|
28
|
Sutera V, Levert M, Burmeister WP, Schneider D, Maurin M. Evolution toward high-level fluoroquinolone resistance in Francisella species. J Antimicrob Chemother 2013; 69:101-10. [PMID: 23963236 DOI: 10.1093/jac/dkt321] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Francisella tularensis, a CDC class A potential bioterrorism agent, is a Gram-negative bacterium responsible for tularaemia. Understanding the mechanisms of resistance to antibiotics used as first-line treatment is of major security relevance. METHODS We propagated the three parental reference strains Francisella tularensis subsp. holarctica live vaccine strain, Francisella novicida and Francisella philomiragia with increasing concentrations of ciprofloxacin, a fluoroquinolone used as curative and prophylactic treatment for tularaemia. This evolution procedure provided us with high-level ciprofloxacin-resistant mutants and all evolutionary intermediates towards high-level resistance. We determined the resistance levels to other fluoroquinolones (levofloxacin and moxifloxacin) and other antibiotic families (aminoglycosides, tetracyclines and macrolides) and characterized the genetic changes in the fluoroquinolone target genes encoding DNA gyrase and topoisomerase IV. RESULTS All high-level resistant mutants shared cross-resistance to the tested fluoroquinolones, while some also revealed striking levels of cross-resistance to other clinically relevant antibiotic classes. High-level resistant mutants carried one to three mutations, including some not previously reported. We mapped all mutations onto known topoisomerase three-dimensional structures. Along the pathways towards high-level resistance, we identified complex evolutionary trajectories including polymorphic states and additional resistance mechanisms likely to be associated with efflux processes. CONCLUSIONS Our data demonstrated the efficiency and speed of in vitro production of mutants highly resistant to fluoroquinolones in Francisella species. They emphasize the urgent need to identify all antibiotic resistance mechanisms in these species, develop molecular tools for their detection and design new therapeutic alternatives for tularaemia.
Collapse
Affiliation(s)
- Vivien Sutera
- Centre Hospitalier Universitaire Grenoble, CS10217, 38043 Grenoble cedex 9, France
| | | | | | | | | |
Collapse
|
29
|
Galán JC, González-Candelas F, Rolain JM, Cantón R. Antibiotics as selectors and accelerators of diversity in the mechanisms of resistance: from the resistome to genetic plasticity in the β-lactamases world. Front Microbiol 2013; 4:9. [PMID: 23404545 PMCID: PMC3567504 DOI: 10.3389/fmicb.2013.00009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 01/09/2013] [Indexed: 11/13/2022] Open
Abstract
Antibiotics and antibiotic resistance determinants, natural molecules closely related to bacterial physiology and consistent with an ancient origin, are not only present in antibiotic-producing bacteria. Throughput sequencing technologies have revealed an unexpected reservoir of antibiotic resistance in the environment. These data suggest that co-evolution between antibiotic and antibiotic resistance genes has occurred since the beginning of time. This evolutionary race has probably been slow because of highly regulated processes and low antibiotic concentrations. Therefore to understand this global problem, a new variable must be introduced, that the antibiotic resistance is a natural event, inherent to life. However, the industrial production of natural and synthetic antibiotics has dramatically accelerated this race, selecting some of the many resistance genes present in nature and contributing to their diversification. One of the best models available to understand the biological impact of selection and diversification are β-lactamases. They constitute the most widespread mechanism of resistance, at least among pathogenic bacteria, with more than 1000 enzymes identified in the literature. In the last years, there has been growing concern about the description, spread, and diversification of β-lactamases with carbapenemase activity and AmpC-type in plasmids. Phylogenies of these enzymes help the understanding of the evolutionary forces driving their selection. Moreover, understanding the adaptive potential of β-lactamases contribute to exploration the evolutionary antagonists trajectories through the design of more efficient synthetic molecules. In this review, we attempt to analyze the antibiotic resistance problem from intrinsic and environmental resistomes to the adaptive potential of resistance genes and the driving forces involved in their diversification, in order to provide a global perspective of the resistance problem.
Collapse
Affiliation(s)
- Juan-Carlos Galán
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal Madrid, Spain ; Centros de Investigación Biomédica en Red en Epidemiología y Salud Pública, Instituto Ramón y Cajal de Investigación Sanitaria Madrid, Spain ; Unidad de Resistencia a Antibióticos y Virulencia Bacteriana Asociada al Consejo Superior de Investigaciones Científicas Madrid, Spain
| | | | | | | |
Collapse
|
30
|
Kalinowski ST, Leonard MJ, Andrews TM, Litt AR. Six classroom exercises to teach natural selection to undergraduate biology students. CBE LIFE SCIENCES EDUCATION 2013; 12:483-93. [PMID: 24006396 PMCID: PMC3763015 DOI: 10.1187/cbe-12-06-0070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural selection and also include discussions on sexual selection, molecular evolution, evolution of complex traits, and the evolution of behavior. The set of six topics gives students the opportunity to see how natural selection operates in a variety of contexts. Pre- and postinstruction testing showed students' understanding of natural selection increased substantially after completing this series of learning activities. Testing throughout this unit showed steadily increasing student understanding, and surveys indicated students enjoyed the activities.
Collapse
|
31
|
Tolba S, Egan S, Kallifidas D, Wellington EMH. Distribution of streptomycin resistance and biosynthesis genes in streptomycetes recovered from different soil sites. FEMS Microbiol Ecol 2012; 42:269-76. [PMID: 19709287 DOI: 10.1111/j.1574-6941.2002.tb01017.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Streptomycin resistant streptomycetes were isolated from four diverse sites. Two sites in Germany were sampled and included an agricultural experimental plot of apple trees which had a history of streptomycin application (AR) and a control site without antibiotic application (CR). Two sites in the UK were sampled; a pastureland site which had sewage injection (DW) and an agricultural site (CW). The actinomycete counts indicated a high proportion of streptomycin resistant isolates in the CW soil. Streptomycetes were identified by partial sequencing of the 16S rDNA. PCR product of the hypervariable gamma region of 16S rDNA allowed analysis by denaturing gradient gel electrophoresis to assess the diversity within the isolates. The streptomycin and sewage sludge treated sites showed decreased diversity within streptomycete populations. Isolates were screened for the streptomycin resistance gene, strA, and flanking biosynthesis gene, strB1. Distribution of these genes indicated the prevalence of str genes in the streptomycin treated soil. Evidence of horizontal gene transfer was recorded in isolates identified as Streptomyces platensis recovered from CR and AR sites which had acquired a streptomycin resistance gene homologous to that found in Streptomyces griseus. Members of the latter species were the most abundant streptomycin resistant streptomycetes isolated from all soils.
Collapse
Affiliation(s)
- Sahar Tolba
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | | | | |
Collapse
|
32
|
Lankau RA. Rapid Evolutionary Change and the Coexistence of Species. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2011. [DOI: 10.1146/annurev-ecolsys-102710-145100] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Richard A. Lankau
- Department of Plant Biology, University of Georgia, Athens, Georgia 30606;
| |
Collapse
|
33
|
Minozzi M, Lattanzi G, Benz R, Costi MP, Venturelli A, Carloni P. Permeation through the cell membrane of a boron-based β-lactamase inhibitor. PLoS One 2011; 6:e23187. [PMID: 21858024 PMCID: PMC3157353 DOI: 10.1371/journal.pone.0023187] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Accepted: 07/11/2011] [Indexed: 11/19/2022] Open
Abstract
Bacteria express beta-lactamases to counteract the beneficial action of antibiotics. Benzo[b]-thiophene-2-boronic acid (BZB) derivatives are β-lactamase inhibitors and, as such, promising compounds to be associated with β-lactam antibacterial therapies. The uncharged form of BZB, in particular, is suggested to diffuse through the outer membrane of gram negative bacteria. In this study, through the combination of electrophysiological experiments across reconstituted PC/n-decane bilayers and metadynamics-based free energy calculations, we investigate the permeation mechanism of boronic compounds. Our experimental data establish that BZB passes through the membrane, while computer simulations provide hints for the existence of an aqueous, water-filled monomolecular channel. These findings provide new perspectives for the design of boronic acid derivatives with high membrane permeability.
Collapse
Affiliation(s)
- Manuela Minozzi
- Modeling & Simulation Lab Department of Studies on Structures, University “Roma Tre”, Roma, Italy
| | - Gianluca Lattanzi
- Department of Basic Medical Sciences, TIRES Centre and Istituto Nazionale di Fisica Nucleare, University of Bari “Aldo Moro”, Bari, Italy
- * E-mail:
| | - Roland Benz
- School of Engineering and Science Jacobs-University Bremen, Bremen, Germany
| | - Maria P. Costi
- University of Modena and Reggio Emilia, Pharmaceutical Sciences Dept., Modena, Italy
| | - Alberto Venturelli
- University of Modena and Reggio Emilia, Pharmaceutical Sciences Dept., Modena, Italy
| | - Paolo Carloni
- German Research School for Simulation Science, Jülich Research Center and RWTH-Aachen University, Jülich, Germany
| |
Collapse
|
34
|
Fox JW, Kerr B. Analyzing the effects of species gain and loss on ecosystem function using the extended Price equation partition. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19656.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
35
|
The occurrence of virulence traits among high-level aminoglycosides resistant Enterococcus isolates obtained from feces of humans, animals, and birds in South Korea. Int J Food Microbiol 2010; 144:387-92. [PMID: 21078531 DOI: 10.1016/j.ijfoodmicro.2010.10.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/19/2010] [Accepted: 10/19/2010] [Indexed: 11/21/2022]
Abstract
Enterococcus isolates (1500) obtained from the feces of 48 humans, 209 domesticated food animals, and 155 wild geese in South Korea were characterized with respect to species status by PCR analyses and resistance to antibiotics. Of the 1500 strains examined, the majority (n=577) were Enterococcus faecalis from 224 (54.4%) of the samples feces, while 299 were of E. faecium from 125 of the samples (30.3%), 224 were E. hirae from 101 (24.5%) of the samples, 94 were E. casseliflavus from 43 (10.4%) of the samples, and one was E. gallinarum. While 305 isolated from 125 (30.3%) of the samples were unidentified species. Approximately 15, 60, 50, 55, 3, and 40% of samples obtained from beef cattle, chickens, ducks, swine, wild geese, and humans, respectively, yielded Enterococcus isolates that were resistant to high-levels of aminoglycosides (i.e., of gentamicin, kanamycin, and streptomycin, minimum inhibitory concentrations were >1000 mg/l). The 180 Enterococcus isolates that showed high levels of resistance to aminoglycoside antibiotics (HLAR) were screened for virulence genes encoding for aggregation substance (agg), cytolysin activator (cylA), gelatinase (gelE) and surface protein (esp). Of those, the gelE gene was found most frequently in chickens and ducks of the HLAR isolates, while 56 E. faecalis and 13 E. faecium HLAR were gelatinase positive and showed hemolysin activity. Multiple antibiotic resistant Enterococcus isolates carrying virulence genes were most frequently isolated from poultry and swine, and were mostly E. faecalis or E. faecium. These findings suggest that restriction of the use of antibiotics in food animal operations in South Korea, especially those involved in poultry and swine production would be desirable.
Collapse
|
36
|
Eddabra R, Moussaoui W, Prévost G, Delalande F, Van Dorsselaer A, Meunier O, Scheftel JM, Mimouni R. Occurrence of Vibrio cholerae non-O1 in three wastewater treatment plants in Agadir (Morocco). World J Microbiol Biotechnol 2010. [DOI: 10.1007/s11274-010-0556-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
37
|
Novais Â, Comas I, Baquero F, Cantón R, Coque TM, Moya A, González-Candelas F, Galán JC. Evolutionary trajectories of beta-lactamase CTX-M-1 cluster enzymes: predicting antibiotic resistance. PLoS Pathog 2010; 6:e1000735. [PMID: 20107608 PMCID: PMC2809773 DOI: 10.1371/journal.ppat.1000735] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 12/21/2009] [Indexed: 02/07/2023] Open
Abstract
Extended-spectrum beta-lactamases (ESBL) constitute a key antibiotic-resistance mechanism affecting Gram-negative bacteria, and also an excellent model for studying evolution in real time. A shift in the epidemiology of ESBLs is being observed, which is characterized by the explosive diversification and increase in frequency of the CTX-M-type beta-lactamases in different settings. This provides a unique opportunity for studying a protein evolutionary radiation by the sequential acquisition of specific mutations enhancing protein efficiency and fitness concomitantly. The existence of driver antibiotic molecules favoring protein divergence has been investigated by combining evolutionary analyses and experimental site-specific mutagenesis. Phylogenetic reconstruction with all the CTX-M variants described so far provided a hypothetical evolutionary scenario showing at least three diversification events. CTX-M-3 was likely the enzyme at the origin of the diversification in the CTX-M-1 cluster, which was coincident with positive selection acting on several amino acid positions. Sixty-three CTX-M-3 derivatives containing all combinations of mutations under positively selected positions were constructed, and their phenotypic efficiency was evaluated. The CTX-M-3 diversification process can only be explained in a complex selective landscape with at least two antibiotics (cefotaxime and ceftazidime), indicating the need to invoke mixtures of selective drivers in order to understand the final evolutionary outcome. Under this hypothesis, we found congruent results between the in silico and in vitro analyses of evolutionary trajectories. Three pathways driving the diversification of CTX-M-3 towards the most complex and efficient variants were identified. Whereas the P167S pathway has limited possibilities of further diversification, the D240G route shows a robust diversification network. In the third route, drift may have played a role in the early stages of CTX-M-3 evolution. Antimicrobial agents should not be considered only as selectors for efficient mechanisms of resistance but also as diversifying agents of the evolutionary trajectories. Different trajectories were identified using a combination of phylogenetic reconstructions and directed mutagenesis analyses, indicating that such an approach might be useful to fulfill the desirable goal of predicting evolutionary trajectories in antimicrobial resistance.
Collapse
Affiliation(s)
- Ângela Novais
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Iñaki Comas
- Unidad Mixta Genómica y Salud CSISP/UV-Instituto Cavanilles, Valencia, Spain
- MRC National Institute for Medical Research, London, United Kingdom
| | - Fernando Baquero
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Rafael Cantón
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Teresa M. Coque
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Andrés Moya
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad Mixta Genómica y Salud CSISP/UV-Instituto Cavanilles, Valencia, Spain
| | - Fernando González-Candelas
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad Mixta Genómica y Salud CSISP/UV-Instituto Cavanilles, Valencia, Spain
| | - Juan-Carlos Galán
- Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| |
Collapse
|
38
|
Handel A, Rozen DE. The impact of population size on the evolution of asexual microbes on smooth versus rugged fitness landscapes. BMC Evol Biol 2009; 9:236. [PMID: 19765292 PMCID: PMC2753573 DOI: 10.1186/1471-2148-9-236] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 09/18/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND It is commonly thought that large asexual populations evolve more rapidly than smaller ones, due to their increased rate of beneficial mutations. Less clear is how population size influences the level of fitness an asexual population can attain. Here, we simulate the evolution of bacteria in repeated serial passage experiments to explore how features such as fitness landscape ruggedness, the size of the mutational target under selection, and the mutation supply rate, interact to affect the evolution of microbial populations of different sizes. RESULTS We find that if the fitness landscape has many local peaks, there can be a trade-off between the rate of adaptation and the potential to reach high fitness peaks. This result derives from the fact that whereas large populations evolve mostly deterministically and often become trapped on local fitness peaks, smaller populations can follow more stochastic evolutionary paths and thus locate higher fitness peaks. We also find that the target size of adaptation and the mutation rate interact with population size to influence the trade-off between rate of adaptation and final fitness. CONCLUSION Our study suggests that the optimal population size for adaptation depends on the details of the environment and on the importance of either the ability to evolve rapidly or to reach high fitness levels.
Collapse
Affiliation(s)
- Andreas Handel
- Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, GA 30602, USA.
| | | |
Collapse
|
39
|
Induction of multidrug resistance mechanism in Escherichia coli biofilms by interplay between tetracycline and ampicillin resistance genes. Antimicrob Agents Chemother 2009; 53:4628-39. [PMID: 19721076 DOI: 10.1128/aac.00454-09] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilms gain resistance to various antimicrobial agents, and the presence of antibiotic resistance genes is thought to contribute to a biofilm-mediated antibiotic resistance. Here we showed the interplay between the tetracycline resistance efflux pump TetA(C) and the ampicillin resistance gene (bla(TEM-1)) in biofilms of Escherichia coli harboring pBR322 in the presence of the mixture of ampicillin and tetracycline. E. coli in the biofilms could obtain the high-level resistance to ampicillin, tetracycline, penicillin, erythromycin, and chloramphenicol during biofilm development and maturation as a result of the interplay between the marker genes on the plasmids, the increase of plasmid copy number, and consequently the induction of the efflux systems on the bacterial chromosome, especially the EmrY/K and EvgA/S pumps. In addition, we characterized the overexpression of the TetA(C) pump that contributed to osmotic stress response and was involved in the induction of capsular colanic acid production, promoting formation of mature biofilms. However, this investigated phenomenon was highly dependent on the addition of the subinhibitory concentrations of antibiotic mixture, and the biofilm resistance behavior was limited to aminoglycoside antibiotics. Thus, marker genes on plasmids played an important role in both resistance of biofilm cells to antibiotics and in formation of mature biofilms, as they could trigger specific chromosomal resistance mechanisms to confer a high-level resistance during biofilm formation.
Collapse
|
40
|
Morley NJ. Environmental risk and toxicology of human and veterinary waste pharmaceutical exposure to wild aquatic host-parasite relationships. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2009; 27:161-175. [PMID: 21783935 DOI: 10.1016/j.etap.2008.11.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Revised: 11/09/2008] [Accepted: 11/12/2008] [Indexed: 05/31/2023]
Abstract
Pollution of the aquatic environment by human and veterinary waste pharmaceuticals is an increasing area of concern but little is known about their ecotoxicological effects on wildlife. In particular the interactions between pharmaceuticals and natural stressors of aquatic communities remains to be elucidated. A common natural stressor of freshwater and marine organisms are protozoan and metazoan parasites, which can have significant effects on host physiology and population structure, especially under the influence of many traditional kinds of toxic pollutants. However, little is known about the effects of waste pharmaceuticals to host-parasite dynamics. In order to assess the risk waste pharmaceuticals pose to aquatic wildlife it has been suggested the use of toxicological data derived from mammals during the product development of pharmaceuticals may be useful for predicting toxic effects. An additional similar source of information is the extensive clinical studies undertaken with numerous classes of drugs against parasites of human and veterinary importance. These studies may form the basis of preliminary risk assessments to aquatic populations and their interactions with parasitic diseases in pharmaceutical-exposed habitats. The present article reviews the effects of the most common classes of pharmaceutical medicines to host-parasite relationships and assesses the risk they may pose to wild aquatic organisms. In addition the effects of pharmaceutical mixtures, the importance of sewage treatment, and the risk of developing resistant strains of parasites are also assessed.
Collapse
Affiliation(s)
- Neil J Morley
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| |
Collapse
|
41
|
Surviving the bottleneck: transmission mutants and the evolution of microbial populations. Genetics 2008; 180:2193-200. [PMID: 18854584 DOI: 10.1534/genetics.108.093013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of microbial populations to increase fitness through fixation of mutants with an increased growth rate has been well described. In experimental studies, this is often the only way fitness can be increased. In natural settings, however, fitness can also be improved by increasing the ability of the microbe to transmit from one host to the next. For many pathogens, transmission includes a phase outside the host during which they need to survive before the chance of reinfecting a new host occurs. In such a situation, a reduced death rate during this phase will lead to improved fitness. Here, we compute the fixation probability of mutants that better survive the transmission bottleneck during the evolution of microbial populations. We derive analytical results that show that transmission mutants are often likely to occur and that their importance relative to growth mutants increases as the population decline during the transmission phase increases. We confirm our theoretical results with numerical simulations and suggest specific experiments that can be done to test our predictions.
Collapse
|
42
|
Bonnedahl J, Olsen B, Waldenström J, Broman T, Jalava J, Huovinen P, Österblad M. Antibiotic susceptibility of faecal bacteria in Antarctic penguins. Polar Biol 2008. [DOI: 10.1007/s00300-008-0430-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
43
|
Evaluation of antibacterial resistance in Vibrio strains isolated from imported seafood and Italian aquaculture settings. FOOD ANAL METHOD 2008. [DOI: 10.1007/s12161-007-9011-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
44
|
Lebarbenchon C, Brown SP, Poulin R, Gauthier-Clerc M, Thomas F. Evolution of pathogens in a man-made world. Mol Ecol 2008; 17:475-84. [PMID: 18173509 PMCID: PMC7168490 DOI: 10.1111/j.1365-294x.2007.03375.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 04/04/2007] [Indexed: 12/03/2022]
Abstract
Human activities have resulted in substantial, large-scale environmental modifications, especially in the past century. Ecologists and evolutionary biologists are increasingly coming to realize that parasites and pathogens, like free-living organisms, evolve as the consequence of these anthropogenic changes. Although this area now commands the attention of a variety of researchers, a broad predictive framework is lacking, mainly because the links between human activities, the environment and parasite evolution are complex. From empirical and theoretical examples chosen in the literature, we give an overview of the ways in which humans can directly or indirectly influence the evolution of different traits in parasites (e.g. specificity, virulence, polymorphism). We discuss the role of direct and indirect factors as diverse as habitat fragmentation, pollution, biodiversity loss, climate change, introduction of species, use of vaccines and antibiotics, ageing of the population, etc. We also present challenging questions for further research. Understanding the links between anthropogenic changes and parasite evolution needs to become a cornerstone of public health planning, economic development and conservation biology.
Collapse
Affiliation(s)
- Camille Lebarbenchon
- Génétique et Evolution des Maladies Infectieuses, UMR CNRS/IRD 2724, IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France
| | | | | | | | | |
Collapse
|
45
|
Koike S, Krapac IG, Oliver HD, Yannarell AC, Chee-Sanford JC, Aminov RI, Mackie RI. Monitoring and source tracking of tetracycline resistance genes in lagoons and groundwater adjacent to swine production facilities over a 3-year period. Appl Environ Microbiol 2007; 73:4813-23. [PMID: 17545324 PMCID: PMC1951052 DOI: 10.1128/aem.00665-07] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tc(r)) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tc(r) genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tc(r) genes was quantified by real-time quantitative PCR. To confirm the Tc(r) gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tc(r) genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tc(r) genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool.
Collapse
Affiliation(s)
- S Koike
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | | | | | | | |
Collapse
|
46
|
Oliver MA, García-Delafuente C, Cano ME, Pérez-Hernández F, Martínez-Martínez L, Albertí S. Rapid decrease in the prevalence of macrolide-resistant group A streptococci due to the appearance of two epidemic clones in Cantabria (Spain). J Antimicrob Chemother 2007; 60:450-2. [PMID: 17540676 DOI: 10.1093/jac/dkm174] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
47
|
Naug D, Smith B. Experimentally induced change in infectious period affects transmission dynamics in a social group. Proc Biol Sci 2007; 274:61-5. [PMID: 17015337 PMCID: PMC1679870 DOI: 10.1098/rspb.2006.3695] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
A key component of any epidemiological model is the infectious period, which greatly affects the dynamics and persistence of an infection. Social organization, leading to behavioural and spatial heterogeneities among potential susceptibles, interacts with infectious period to create different risk categories within a group. Using the honeybee (Apis mellifera) colony as a social model, a protocol that creates different infectious periods in individual bees and another that follows the diffusion of a transmittable tracer within a colony, we show experimentally how a short infectious period results in an epidemic process with low prevalence confined only to individuals at the outer edge of a group, while a long infectious period results in high prevalence distributed more universally among all the group members. We call this finding an evidence of 'organizational immunity' in a social network and propose that the honeybee colony provides a unique opportunity to test its role in social transmission processes.
Collapse
Affiliation(s)
- Dhruba Naug
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
| | | |
Collapse
|
48
|
McMillan AM, Bagley MJ, Jackson SA, Nacci DE. Genetic diversity and structure of an estuarine fish (Fundulus heteroclitus) indigenous to sites associated with a highly contaminated urban harbor. ECOTOXICOLOGY (LONDON, ENGLAND) 2006; 15:539-48. [PMID: 16988885 DOI: 10.1007/s10646-006-0090-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/23/2006] [Indexed: 05/04/2023]
Abstract
Intense selection on isolated populations can cause loss of genetic diversity, which if persistent, reduces adaptive potential and increases extinction probability. Phenotypic evidence of inherited tolerance suggests that polychlorinated biphenyls (PCBs), have acted as strong selective agents on populations of a non-migratory fish, Fundulus heteroclitus, indigenous to heavily contaminated sites. To evaluate population genetic structure and test for effects of intense, multi-generational PCB contamination on genetic diversity, we used AFLP analysis on fish collected from six sites along the east coast of North America that varied widely in PCB contamination. The sites included a heavily contaminated urban harbor (New Bedford, MA), an adjacent moderately contaminated sub-estuary (Buzzards Bay, MA), and an uncontaminated estuary 60 km away (Narragansett, RI). AFLP markers distinguished populations at moderate and small scales, suggesting genetic differentiation at distances of 2 km or less. Genetic diversity did not differ across the study sites. Genome-wide diversity may have been preserved because of large effective population sizes and/or because the mechanism for genetic adaptation to these contaminants affected only a small number of loci. Alternatively, loss in diversity may have been restored with moderate levels of migration and relatively short generation time for this species.
Collapse
Affiliation(s)
- Amy M McMillan
- Biology Department, State University of New York College at Buffalo, 1300 Elmwood Ave., Buffalo, NY 14222, USA.
| | | | | | | |
Collapse
|
49
|
Read JM, Keeling MJ. Disease evolution across a range of spatio-temporal scales. Theor Popul Biol 2006; 70:201-13. [PMID: 16765401 DOI: 10.1016/j.tpb.2006.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 04/15/2006] [Accepted: 04/17/2006] [Indexed: 11/24/2022]
Abstract
Traditional explorations of infectious disease evolution have considered the competition between two cross-reactive strains within the standard framework of disease models. Such techniques predict that diseases should evolve to be highly transmissible, benign to the host and possess a long infectious period: in general, diseases do not conform to this ideal. Here we consider a more holistic approach, suggesting that evolution is a trade-off between adaptive pressures at different scales: within host, between hosts and at the population level. We present a model combining within-host pathogen dynamics and transmission between individuals governed by an explicit contact network, where transmission dynamics between hosts are a function of the interaction between the pathogen and the hosts' immune system, though ultimately constrained by the contacts each infected host possesses. Our results show how each of the scales places constraints on the evolutionary behavior, and that complex dynamics may emerge due to the feedbacks between epidemiological and evolutionary dynamics. In particular, multiple stable states can occur with switching between them stochastically driven.
Collapse
Affiliation(s)
- Jonathan M Read
- Department of Biological Sciences and Mathematics Institute, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
| | | |
Collapse
|
50
|
Wang Y, Leung PC, Qian PY, Gu JD. Antibiotic resistance and plasmid profile of environmental isolates of Vibrio species from Mai Po Nature Reserve, Hong Kong. ECOTOXICOLOGY (LONDON, ENGLAND) 2006; 15:371-8. [PMID: 16680524 DOI: 10.1007/s10646-006-0078-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/01/2006] [Indexed: 05/09/2023]
Abstract
In this study, three environmental isolates of Vibrio species were isolated from water and sediment samples of Mai Po Nature Reserve, Hong Kong SAR. They were identified to be Vibrio cholerae MP-1, Vibrio aestuarianus MP-2 and Vibrio vulnificus MP-3 by both biochemical test and subsequent full-length 16S rDNA sequencing. Both disc diffusion susceptibility test and microplate dilution technique were used to investigate the antibiotic resistance profile of these three bacteria. Results from both assays were in generally good agreement. All three isolates were strongly resistant to beta-lactam family of antibiotics while susceptible to tetracycline, chloramphenicol, nalidixic acid and streptomycin. In addition, V. cholerae MP-1 was very tolerant to high concentration of vibriostatic agent O/129 to 40 microg/ml, at which the growth of V. aestuarianus MP-2 and V. vulnificus MP-2 was completely inhibited. A small naturally occurring plasmid was found in V. cholerae MP-1 while no plasmid was detected in the other two bacteria. This study suggests that Mai Po Nature Reserve harbors bacteria of unique characteristics that warrant further investigation.
Collapse
Affiliation(s)
- Yanling Wang
- Laboratory of Environmental Toxicology, Department of Ecology & Biodiversity, The University of Hong Kong, Hong Kong SAR, PR China
| | | | | | | |
Collapse
|