Stress responses as determinants of antimicrobial resistance in Gram-negative bacteria

Author: Poole, K. Description: Bacteria encounter a myriad of potentially growth-compromising conditions in nature and in hosts of pathogenic bacteria. These ‘stresses’ typically elicit protective and/or adaptive responses that serve to enhance bacterial survivability. Because they impact upon many of the same cellular components and processes that are targeted by antimicrobials, adaptive stress responses can influence antimicrobial susceptibility. In targeting and interfering with key cellular processes, antimicrobials themselves are ‘stressors’ to which protective stress responses have also evolved. Cellular responses to nutrient limitation (nutrient stress), oxidative and nitrosative stress, cell…

See more and a link to full text

Long-term application of fresh and composted manure increase tetracycline resistance in the arable soil of eastern China

Author: Peng, S.; Wang, Y.; Zhou, B.; Lin, X. Description: The aim of this study was to compare the occurrence, abundance, and diversity of tetracycline resistance genes (tet) in agricultural soils after 6 years’ application of fresh or composted swine manure. Soil samples were collected from fresh or composted manure-treated farmland at three depths (0-5 cm, 5-10 cm, and 10-20 cm). Nine classes of tet genes [tetW, tetB(P), tetO, tetS, tetC, tetG, tetZ, tetL, and tetX] were detected; tetG, tetZ, tetL, and tetB(P) were predominant in the manure-treated soil. The…

See more and a link to full text

Detection of hepatitis E virus and other livestock-related pathogens in Iowa streams

Author: Givens, C.E.; Kolpin, D.W.; Borchardt, M.A.; Duris, J.W.; Moorman, T.B.; Spencer, S.K. Description: Manure application is a source of pathogens to the environment. Through overland runoff and tile drainage, zoonotic pathogens can contaminate surface water and streambed sediment and could affect both wildlife and human health. This study examined the environmental occurrence of gene markers for livestock-related bacterial, protozoan, and viral pathogens and antibiotic resistance in surface waters within the South Fork Iowa River basin before and after periods of swine manure application on agricultural land. Increased concentrations of…

See more and a link to full text

Molecular mechanisms of antibiotic resistance

Author: Blair, J.M.A.; Webber, M.A.; Baylay, A.J.; Ogbolu, D.O.; Piddock, L.J.V. Description: Antibiotic-resistant bacteria that are difficult or impossible to treat are becoming increasingly common and are causing a global health crisis. Antibiotic resistance is encoded by several genes, many of which can transfer between bacteria. New resistance mechanisms are constantly being described, and new genes and vectors of transmission are identified on a regular basis. This article reviews recent advances in our understanding of the mechanisms by which bacteria are either intrinsically resistant or acquire resistance to antibiotics, including…

See more and a link to full text

A Hundred Years of Bacteriophages: Can Phages Replace Antibiotics in Agriculture and Aquaculture?

Author: Sieiro, C.; Areal-Hermida, L.; Pichardo-Gallardo, Á.; Almuiña-González, R.; de Miguel, T.; Sánchez, S.; Sánchez-Pérez, Á. & Villa, T. G. Description: Agriculture, together with aquaculture, supplies most of the foodstuffs required by the world human population to survive. Hence, bacterial diseases affecting either agricultural crops, fish, or shellfish not only cause large economic losses to producers but can even create food shortages, resulting in malnutrition, or even famine, in vulnerable populations. Years of antibiotic use in the prevention and the treatment of these infections have greatly contributed to the emergence…

See more and a link to full text

Antibiotics, microbiota, and immune defense

Author: Ubeda, C.; Pamer, E.G. Description: The gastrointestinal tract microbiota contributes to the development and differentiation of the mammalian immune system. The composition of the microbiota affects immune responses and affects susceptibility to infection by intestinal pathogens and development of allergic and inflammatory bowel diseases. Antibiotic administration, while facilitating clearance of targeted infections, also perturbs commensal microbial communities and decreases host resistance to antibiotic-resistant microbes. Here, we review recent advances that begin to define the interactions between complex intestinal microbial populations and the mammalian immune system and how this relation…

See more and a link to full text

Antibiotic treatments and microbes in the gut

Author: Macfarlane, S. Description: Antibiotic therapies are important in combating disease-causing microorganisms and maintaining host health. It is widely accepted that exposure of the gut microbiota to antibiotics can lead to decreased susceptibility and the development of multi-drug-resistant disease-causing organisms, which can be a major clinical problem. It is also important to consider that antibiotics not only target pathogenic bacteria in the gut, but also can have damaging effects on the ecology of commensal species. This can reduce intrinsic colonization resistance and contribute to problems with antibiotic resistance, including lateral…

See more and a link to full text

Co-selection of multi-antibiotic resistance in bacterial pathogens in metal and microplastic contaminated environments: An emerging health threat

Author: Imran, Md; Das, Kirti Ranjan; Naik, Milind Mohan Description: Misuse/over use of antibiotics increases the threats to human health since this is a main reason behind evolution of antibiotic resistant bacterial pathogens. However, metals such as mercury, lead, zinc, copper and cadmium are accumulating to critical concentration in the environment and triggering co-selection of antibiotic resistance in bacteria. The co-selection of metal driven antibiotic resistance in bacteria is achieved through co-resistance or cross resistance. Metal driven antibiotic resistant determinants evolved in bacteria and present on same mobile genetic elements…

See more and a link to full text

Bacterial antibiotic resistance studies using in vitro dynamic models: Population analysis vs. susceptibility testing as endpoints of mutant enrichment

Author: Firsov, A.A.; Strukova, E.N.; Portnoy, Y.A.; Shlykova, D.S.; Zinner, S.H. Description: Emergence of bacterial antibiotic resistance is usually characterized either by population analysis or susceptibility testing. To compare these endpoints in their ability to demonstrate clear relationships with the ratio of 24-h area under the concentration-time curve (AUC24) to the minimum inhibitory concentration (MIC), enrichment of ciprofloxacin-resistant mutants of four clinical isolates of Pseudomonas aeruginosa was studied in an in vitro dynamic model that simulates mono-exponential pharmacokinetics of ciprofloxacin over a wide range of the AUC24/MIC ratios. Each organism…

See more and a link to full text

Fate and transport of antibiotic residues and antibiotic resistance genes following land application of manure waste

Author: Chee-Sanford, J.C.; Mackie, R.I.; Koike, S.; Krapac, I.G.; Lin, Y.-F.; Yannarell, A.C.; Maxwell, S.; Aminov, R.I. Description: Antibiotics are used in animal livestock production for therapeutic treatment of disease and at subtherapeutic levels for growth promotion and improvement of feed efficiency. It is estimated that approximately 75% of antibiotics are not absorbed by animals and are excreted in waste. Antibiotic resistance selection occurs among gastrointestinal bacteria, which are also excreted in manure and stored in waste holding systems. Land application of animal waste is a common disposal method used…

See more and a link to full text