Fiona Walsh, Agroscope Changins Wädenswil, Wädenswil, Switzerland, has written an interesting overview of antibiotics and antibiotic resistance for Frontiers Microbiology.
Posted by Tim Sandle
There have been many calls for more information about
the natural resistome and these have also highlighted the importance of
understanding the environmental resistome in the preservation of
antibiotics for the treatment of infections. However, to date there have
been few studies which have investigated the roles of antibiotics and
resistances outside of the clinical environment. This lack of data also
highlights the difficulties faced by microbiologists in designing these
experiments to produce meaningful data. Antibiotics and antibiotic
resistance have most commonly been viewed in the context of human use
and effects. However, both have co-existed in nature for millennia.
Recently the roles of antibiotics and antibiotic resistance genes have
started to be discussed in terms of functions other than bacterial
inhibition and protection. This special topic has focused on both the
traditional role of antibiotics as warfare mechanisms and their
alternative roles and uses within nature.
The research topic starts with an introduction into
antimicrobial resistance in medicine, its linkage to the global
environmental microbiota and the many different roles of antibiotics and
antibiotic resistance in nature, providing the background to the topic (Cantas et al., 2013).
The following chapter discusses the idea that the understanding of
antibiotic resistance implies expanding our knowledge on multi-level
population biology of bacteria (Baquero et al., 2013).
This brings with it inherent problems of designing experimental
procedures and standards that can be used in many different microbiomes
from human to soil and is discussed further by Walsh (Walsh, 2013).
A number of models are proposed to study and understand the biological
impact of selection and diversification of antibiotic resistance
mechanisms, in particular using the β-lactamases as models (Galán et al., 2013; Patel and Bonomo, 2013; Popowska and Krawczyk-Balska, 2013).
The β-lactamases constitute the most widespread mechanism of
resistance, at least among pathogenic bacteria, with more than 1000
enzymes identified in the literature. We present some examples of the
alternative functions for the multi-drug resistance mechanisms of
efflux, that range from bacterial interactions with plant or animal
hosts, to the detoxification of metabolic intermediates or the
maintenance of cellular homeostasis and also the potential role of
extracellular DNA in antibiotic resistance and virulence (Alvarez-Ortega et al., 2013).
Bacterial responses to antibiotics may be concentration dependent and
so we discuss the different types of interactions mediated by
antibiotics and non-antibiotic metabolites as a function of their
concentrations and speculate on how these may amplify the overall
antibiotic resistance/tolerance and the spread of antibiotic resistance
determinants in a context of poly-microbial community (Bernier and Surette, 2013; Lewenza, 2013; Sengupta et al., 2013).
The use of antibiotics may also be regarded as pollution. Thus, the
widespread use and abuse of antibiotic therapy has evolutionary and
ecological consequences, some of which are only just beginning to be
examined (Gillings, 2013).
These papers thoroughly review the many different aspects
of antibiotic resistance and the roles of antibiotics in nature and
link these to the emerging antibiotic resistances of particular
importance to the treatment of infectious diseases.
References
Posted by Tim Sandle
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