Resistance to antibacterials

The second general mechanism to cause resistance to antibacterial agents is to prevent the drug from reaching its target site. This is either achieved by altered rates of entry (reduced uptake) or by the active removal of the dtug (active efflux) [4]. 

Physical methods for the control of microbial biofilms, although often effective, are in many situations impractical. In this context it is notable that an almost universal feature of the biofilm mode of growth is their profound resistance to antibacterial compounds. Conventional chemical control methods, developed for use against fastgrowing planktonic cultures are only poorly effective against biofilm bacteria. Large doses of biocide or antibiotics, which are either environmentally undesirable or above toxic thresholds respectively, are required to eradicate biofilms in industry and medicine. 

It must be emphasized that the subject of bacterial resistance to antibacterial agents is a huge one. Consequently, as far as possible, only recent theories and practicalities will be described here, and reviews will be cited frequently, although occasionally some older work will perforce be referred to when necessary. 

It is clear from the preceding sections that bacterial resistance to antibacterial agents, especially antibiotics, is of mounting concern. Increasingly, therefore, attention is being devoted to ways of overcoming this problem. This section will thus consider possible means of counteracting bacterial resistance. 

In general terms, bacterial resistance to antibacterial agents can be considered as being either intrinsic (innate, a natural property) or acquired, for example, by mutation or by the acquisition of a plasmid or transposon (jumping gene) [105]. Resistance to mercury [103, 122-125] and to other cations and anions [103, 122, 123, 125] is well characterized. The mechanisms involved in resistance to some metals, including silver, are summarized in Table 7.1. 

Richards RME, Richards JM. Pseudomonas cepacia resistance to antibacterials. 7 Pharm Sci 1979 68 1436-1438. 

Davies D. 2003. Understanding biofihn resistance to antibacterial agents. Nature Rev Drug Discov 2 114-122. 

Davies, D. (2003). Understanding biofilm resistance to antibacterial agents. Nat. Rev. Drug Discov. 2,114-122. 

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