What is the difference between a biocide and an antibiotic

They are considered to be multitarget reactors 11 , 74 that act on cell walls and the amino groups in proteins, but their primary effect is believed to be either or both i the progressive oxidation of thiol groups to disulphides, sulphoxides and disulphoxides 17 , 50 , 75 and ii deleterious effects on DNA synthesis resulting from the formation of chlorinated derivatives of nucleotide bases.

Chlorine dioxide shows activity against bacteria, fungi, protozoa and algae. Its primary molecular target remains unclear, but inhibition of protein synthesis may be involved as well as membrane damage. Iodine, used as an aqueous with potassium iodide or alcoholic solution, is an effective microbicidal agent with rapid lethal effects against bacteria and their spores, moulds, yeasts and viruses.

They retain the germicidal action but not the undesirable properties of iodine. The concentration of free iodine in both types is responsible for activity. Iodine interacts with thiol groups in enzymes and proteins 11 , 17 and this is believed to be responsible for its bactericidal, sporicidal and fungicidal actions.

Iodine causes extensive morphological changes to the poliovirus structure by affecting the viral capsid rather than RNA. Iodination of phenolic and imidazole groups of tyrosine and histidine and lipid interactions in lipid-enveloped viruses 82 and phospholipids in bacteria 83 also contribute to its lethality.

According to Melly et al. Damage to spore DNA has been described. PAA is the most potent peroxygen. Although the mechanisms of action of these two peroxygens have not been widely studied against other microorganisms, their multi-targeted effects suggest that similar mechanisms might be responsible for microbial inactivation.

Ozone is a powerful bactericidal, sporicidal and fungicidal agent, 85 although yeasts and moulds are less susceptible than bacteria. However, Rennecker et al. Nevertheless, ozone is considered to be superior to any of the halogens against Cryptosporidium oocysts or E.

The mechanisms of ozone action are unknown. It is considered to disrupt cellular enzyme activity by reacting with thiol groups, but also modifies purine and pyrimidine bases in nucleic acids. Several phenols are used for disinfectant or preservative purposes. Fentichlor, a chlorinated phenol, acts as an uncoupling agent against susceptible bacteria. Bacterial spores are very resistant even to high concentrations of phenol, but germination is inhibited by low phenol concentrations.

The phenylether, triclosan [5-chloro 2,4-dichlorophenoxy phenol], is a broad-spectrum antimicrobial agent. Much higher concentrations are bactericidal, but P. Yeasts and moulds tend to be much less susceptible than S. Triclosan is membrane-active, but studies have also indicated that its growth-inhibitory properties against S. Some bacteria possess triclosan-resistant enoyl-ACP reductase homologues FabK and both triclosan-susceptible and -resistant enzymes can be found in P.

Benzoic and sorbic acids are active against Gram-positive and Gram-negative bacteria and yeasts, and inhibit spore germination but are not sporicidal. The most widely used esters are the parabens [methyl, ethyl, propyl and butyl esters of para 4 -hydroxybenzoic acid].

Silver salts and other heavy metals act by binding to key functional groups of fungal enzymes. They are all capable of inactivating bacteria and spores, fungi and viruses and it is likely that that this inactivation is brought about in a similar manner in each type of organism. Interactions of formaldehyde with viral nucleic acids have been described. The bacterial spore cycle and encystation and excystation in the simpler forms of protozoa provide excellent tools for associating morphological and biochemical changes in cells with susceptibility to antimicrobial agents, both antibiotics and biocides Table 4.

Members of the genera Bacillus and Clostridium have complex life cycles with the two extremes of dormant spore and metabolically active vegetative cell forms. Seven stages have been identified in the sporulation of B.

Small acid-soluble proteins SASPs exist in the spore core as two types. Despite being metabolically dormant, the spore contains a number of enzymes that act on the corresponding substrates in a very short period of time during germination. During germination phase I, cation and DPA dipicolinic acid release, partial core hydration and SASP degradation occur, with cortex hydrolysis and further core hydration during germination phase II, followed by biosynthetic processes, escape from spore coats and eventual cell division.

During periods of stress, trophozoites of Acanthamoeba spp. Extensive changes occur during encystation in A. Resistance to several biocides commences with the synthesis of the cellulose-containing wall, implying that a physical barrier is responsible for this decreased susceptibility rather than it being a consequence of a metabolically dormant cyst.

The rates of propidium iodide penetration were substantially higher in filamentous forms when exposed to CHX. Applied stress is i any deviation from the optimum growth condition that produces a reduced growth rate, ii exposure to an environmental situation that produces damage to cellular components in the absence of a cellular response, or iii a situation that stimulates the expression of genes known to respond to a specific environmental condition.

Stress adaptation refers to the ability of bacteria or other microorganisms to adapt to a chemical or other applied stress. Gould pointed out that vegetative bacterial cells react homeostatically to stress in a variety of ways; these include the activation and expres-sion of latent groups of genes following exposure to oxidative stress. Oxidative stress and the SOS response in E. When E. This is essential for long-term survival of the cell and is partly mediated by alternative sigma factors.

Programmed cell death PCD is a programmed suicide mechanism, with persisters being defective in PCD and using the exudate from lysed cells as a source of nutrient. Highly metabolic cells, which are more susceptible to biocides, can be readily differentiated from stationary phase cells by this phenomenon.

The adaptational network of B. Stress response proteins are induced when sporulating cells are heat-shocked. Stress adaptation responses are also known in yeasts. These responses are i intrinsic constitutive and depend on growth phase and the stage of an organism in its life cycle, or ii inducible. These can damage cellular nucleic acids, proteins and lipids. The main defence systems in S. As with vegetative bacterial cells, yeast cells can adapt to a subsequent dose of hydrogen peroxide.

During this adaptation, several polypeptides are induced, some of which are unique to peroxide treatment with others also being produced following heat shock. Catalase and possibly glutathione play a role in this adaptive response. Stresses such as heat, oxidative stress and pH shock on Acanthamoeba trophozoites have been studied.

Resistance to biocidal agents has been widely studied in bacteria 11 and to some extent in fungi, 27 with some useful information beginning to emerge with some types of protozoa Table 5. Gram-negative bacteria, and especially P. This aspect has been considered in greater detail elsewhere. This could prove to be a worthwhile investigation.

In terms of their biocide susceptibility, mycobacteria occupy an intermediate position between bacterial spores and other bacteria. The major reason for their recalcitrance to biocide activity is the lipid-rich, waxy cell wall which limits intracellular uptake of many biocides. Bacterial spores tend to be much less susceptible to biocidal agents than non-sporulating bacteria.

An obvious reason is to be found with the nature and composition of the spore coats and possibly cortex Table 1 which present an effective permeability barrier to the entry of many biocides. Antibiotic resistance in yeasts is known to occur via target site mutations and reduced uptake impermeability and efflux.

However, when used in combination with the polyenic antifungal drug, amphotericin B which combines with fungal membrane sterol , it shows activity against several fungal species. This has led to the suggestion that increased uptake of rifampicin occurs as a consequence of amphotericin action and that membrane sterols pose a barrier to its entry.

CHX and QACs cause damage to the yeast plasma membrane; , 51 , 52 it is not, however, known whether this interaction is reduced by the presence of membrane sterols which could effectively limit further uptake into the cell interior. The outer layers of protozoal cysts are likely to act as a barrier to some biocides.

The outer shell of Cryptosporidium oocysts renders them more resistant to biocides. Biocides are considered to be multitargeted chemical agents. Mutation in the target enzyme or its overproduction can lead to considerable increases in MICs.

With alcohols, the lipid composition and plasma fluidity play a role in the susceptibility of yeasts. Efflux is a major mechanism for the resistance shown by bacteria to antibiotics. Efflux of antifungal antibiotics has also been described. The mechanisms of reduced susceptibility to biocides and antibiotics of bacterial cells present within biofilms have been the subject of considerable experimentation and debate.

In nature, it is likely that biofilms will consist of mixed populations of different types of microorganisms. Many types of bacteria and yeasts interact with protozoa, e. Legionella pneumophila within Acanthamoeba cysts are protected from the action of chlorine.

With algae, the presence of mats equates to biofilms and constant dosing with biocides may be needed to prevent algal recontamination. These can coat spore DNA, thereby protecting it from damage by enzymes and antibacterial agents. They thus play an important role in determining spore susceptibility to antibacterial agents. It is important to understand the reactions of different types of microorganisms to biocidal agents. This is useful from the point of view of cell structure and physiology but also provides valuable information about i the mechanisms of action of biocides, ii the mechanisms whereby microorganisms resist biocide action, and iii the improved usage of biocides in clinical and environmental situations.

With the emergence of new pathogenic organisms and the current level of concern about microbes used as bioterrorism weapons, it is increasingly important to understand the actions and effects of biocidal agents on as wide a range of organisms as possible and of how organisms might resist those actions.

Additionally, yeasts and fungi are more closely related to mammalian cells than originally thought and can be used as screening tools to elucidate the mechanisms of action of antineoplastic agents. It is clear that antibiotics generally are very selective for the type of organism against which they are used.

This implies that different organisms, despite their varied structures, have similar target sites, although with algae, for example, so many different types are known that it is impossible to generalize. In particular, when considering the mechanisms of antimicrobial activity of biocidal agents, compounds that interact with proteins, enzymes or nucleic acids are likely to be effective against a wide range of microorganisms probably as a result of the same basic actions.

The reasons for the variations in non- susceptibility arising between different types of microorganisms can then be ascribed to: i the considerable differences in adsorption by and uptake into cells resulting from the dissimilarities in chemical composition and architecture of the outer cell layers—this is an area where much additional information is needed, but is clearly of considerable importance. Concentration is a key issue in biocide activity 1 and is particularly relevant to the present discussion; ii possible slight or marked differences in the actual target site s so that the affinity of the site s for a biocide is modified; iii possible differences in the amounts of available target site s ; iv the presence within some types of cells of protective chemicals such as the spore-specific SASPs that protect against DNA damage; v stress responses, i.

For example, an SOS response, an efflux pump safety mechanism, or biocide degradation actually unlikely at in-use concentrations of biocide, although one claimed mechanism for the reduced susceptibility of biofilm cells in different types of microbial cells must be considered; and vi the presence of a biofilm an increasingly important field of study or, in the case of algae, a mat, that is responsible for the recalcitrance shown by cultures to biocides.

Further investigations on the relative responses of different types of microbes to biocides should build on current knowledge with the ultimate overall aim of achieving greater understanding of the action and resistance mechanisms involved and of the control of microbial inactivation processes. Figure 1.

Relative susceptibility of entities prions, viruses and microorganisms to biocides. Algae not shown, but likely to be susceptible to at least some biocides. Figure 2. General pattern of biocide entry into different types of microorganisms for simplicity, no barrier function is envisaged. Figure 3. Sporogenesis and susceptibility and resistance to biocides. For role of SASPs, see text. The yeast S. McDonnell, G. Antiseptics and disinfectants: activity, action and resistance. Clinical Microbiology Reviews 12 , — Russell, A.

Bacterial resistance to disinfectants: present knowledge and future problems. Journal of Hospital Infection 43 , S57 — Dychdala, G. Chlorine and chlorine compounds. Knapp, J. Chlorine dioxide. Merianos, J.

Surface-active agents. Hurst, C. Disinfection of water: drinking water, recreational water and wastewater. Blackwell Science, Oxford, UK. Concentration: a major factor in studying biocidal action. Journal of Hospital Infection 44 , 1 —3. Microbial susceptibility and resistance to biocides.

ASM News 63 , —7. Ghannoum, M. Antifungal agents: mode of action, mechanisms and correlation of these mechanisms with bacterial resistance.

Understanding Antibacterial Action and Resistance , 2nd edn. Ellis Horwood, Chichester, UK. Murray-Guide, C. Algicidal effectiveness of Clearigate, Cutrine-Plus and copper sulfate and margins of safety asociated with their use. Archives of Environmental Contamination and Toxicology 43 , 19 — Wang, Y. Studies on bactericidal and algacidal ability of chlorine dioxide. Water Treatment 10 , — Lopes, J. Food- and water-infective micro-organisms.

Parfitt, K. The Complete Drug Reference , pp. Pharmaceutical Press, London, UK. Croft, S. Antiprotozoal drugs: some echoes, some shadows. Hugo, W. Disinfection mechanisms. Gilbert, P. The uptake of some membrane-active drugs by bacteria and yeast: possible microbiological examples of Z-curve adsorption. Journal of Colloid and Interfacial Science 64 , —9.

The adsorption of iodine from solution by micro-organisms and by serum. Journal of Pharmacy and Pharmacology 16 , 49 — Mechanisms of bacterial resistance to antibiotics and biocides. Progress in Medicinal Chemistry 35 , — Susceptibility of porin and lipopolysaccharide defective strains of Escherichia coli to a homologous series of esters of p -hydroxybenzoic acid. International Journal of Pharmaceutics 27 , — The effects of antiseptics, disinfectants and preservatives on smooth, rough and deep rough strains of Salmonella typhimurium.

International Journal of Pharmaceutics 34 , — Journal of Hospital Infection 8 , 47 — International Journal of Pharmaceutics 36 , —7. Sequential loss of outer membrane lipopolysaccharides and sensitivity of Escherichia coli to antibacterial agents. International Journal of Pharmaceutics 35 , — Activity of biocides against mycobacteria. Journal of Applied Bacteriology 81 , 87S —S.

Biocides: mechanisms of antifungal action and fungal resistance. Science Progress 79 , 27 — Turner, N. Acanthamoeba spp. Science Progress 82 , 1 —8. Jarroll, E. Sensitivity of protozoa to disinfectants. Intestinal protozoa. Hiom, S. The possible role of yeast cell walls in modifying cellular responses to chlorhexidine.

Cytobios 86 , — Gerston, H. Fungal spore walls as a possible barrier against potential antifungal agents of the group copper II complexes of 5-halogeno- and 5-nitroquinolinols. Contributions of the Boyce Thompson Institute 23 , — Scherrer, R. Porosity of the yeast cell wall and membrane. Journal of Bacteriology , — De Nobel, J.

The glucanase-soluble mannoproteins limit cell wall porosity in Saccharomyces cerevisiae. Yeast 6 , —9. Baldan, B. European Journal of Histochemistry 45 , 51 —6. Power, E. Glutaraldehyde: its uptake by sporing and non-sporing bacteria, rubber, plastic and an endoscope. Journal of Applied Bacteriology 67 , — Williams, N. The effects of some halogen-containing compounds on Bacillus subtilis endospores. Journal of Applied Bacteriology 70 , — Revival of biocide-treated spores of Bacillus subtilis.

Journal of Applied Bacteriology 75 , 69 — Jarlier, V. Mycobacterial cell walls: structure and role in natural resistance to antibiotics. Lambert, P. Cellular impermeability and uptake of biocides and antibiotics in Gram-positive bacteria and mycobacteria.

Journal of Applied Microbiology 92 , 46 —54S. Fraise, A. Susceptibility of antibiotic-resistant bacteria to biocides.

Journal of Applied Microbiology 92 , —62S. Simons, C. A note: Ortho -phthalaldehyde: proposed mechanism of action of a new antimicrobial agent. Letters in Applied Microbiology 31 , — Navarro, J. Annales de Microbiologie Paris B , — Chambon, M. Activity of glutaraldehyde at low concentrations against capsid proteins of poliovirus type 1 and echovirus type Applied and Environmental Microbiology 58 , — Korn, A. Glutaraldehyde: nature of the reagent. Journal of Molecular Biology 65 , —9.

Walsh, S. Ortho -phthalaldehyde: a possible alternative to glutaraldehyde for high level disinfection. Journal of Applied Microbiology 87 , — Possible mechanisms for the relative efficacies of ortho -phthalaldehyde and glutaraldehyde against glutaraldehyde-resistant Mycobacterium chelonae.

Journal of Applied Microbiology 91 , 80 — Fraud, S. Comparison of the mycobactericidal activity of ortho- phthalaldehyde, glutaraldehyde and other dialdehydes by a quantitative suspension test. A sub-set of 30 isolates selected according to antimicrobial resistance profile and food type were identified by 16S rDNA sequencing and tested for copper and zinc tolerance.

Then, the genetic determinants for biocide and metal tolerance and antibiotic resistance were investigated. The selected isolates were identified as Pseudomonas Antibiotic resistance determinants detected included sul1 These results suggest that exposure to metals could co-select for antibiotic resistance and also highlight the potential of bacteria on seafoods to be involved in the transmission of antimicrobial resistance genes.

Carbapenemase-producing Enterobacteriaceae are particularly of concern because they tend to spread, making infection treatment difficult Iovleva and Doi, Others like the efflux pump oqxAB described in Escherichia coli , confer resistance to various antibiotics and biocides Hansen et al. Different types of selective pressure such as antibiotics, biocides, or heavy metals could play a role in the prevalence of antimicrobial resistance in the food chain. Biocides may co-select strains resistant to antibiotics of clinical use, as verified in the case of triclosan, and others Chuanchuen et al.

A study of microbial populations in environments contaminated with QACs related the increased incidence of resistance to QACs with a higher incidence of class I integrons Gaze et al. Other antimicrobials such as lysozyme-EDTA combinations and chemical preservatives such as sodium lactate and trisodium phosphate also deserve attention because of their wide use and potential applications in the food industry for decontamination and food preservation Lucera et al.

There is also a growing interest in extending the use of plant essential oils or their antimicrobial compounds such as carvacrol or thymol for disinfection and food preservation Lucera et al. One study showed that exposure to pine oil induced a decreased susceptibility to a range of antimicrobial compounds including antibiotics and biocides; Moken et al. Metal salts are used for decontamination in fish farming. Metals such as copper Cu and zinc Zn are essential micronutrients in living things, but they can become toxic if they are above a certain concentration.

Copper and zinc are frequently used in aquaculture and also as antifouling paints on boats Yebra et al. Copper can be released into the environment by both human activities and natural processes.

Zinc is rarely found in nature in its metallic state, but many minerals contain zinc as a main component. The main anthropogenic sources of zinc are mining, zinc production facilities, iron, and steel production, corrosion of galvanized structures, coal, and fuel combustion, waste disposal and incineration, and the use of fertilizers, and pesticides containing zinc WHO, Fish can accumulate and transmit heavy metals along the food chain.

The genes that control resistance to metals may be associated with plasmids, which provide bacteria a competitive advantage over other organisms when specific metals are present Trevors et al. The aim of this study was to provide insights on resistance to clinically relevant antibiotics in bacterial strains isolated from seafood sold at supermarkets and fishmarket.

Therefore, susceptibility of bacterial strains isolated from different seafood samples against various biocides, antibiotics, and metals was evaluated, and the presence of resistance genes in multiresistant strains was determined.

A total of 22 seafood samples from 16 different fish and seafood species purchased at supermarkets and fishmarket in the province of Jaen Spain during the years and were investigated Table 1. Unless indicated, samples consisted of unprocessed whole specimens from sea fishing, and were sold over the counter on ice. Table 1. Sensitivity to antibiotics, biocides and other antimicrobials in bacterial isolates recovered from seafoods. A collection of 87 bacteria randomly isolated from the different seafood samples were screened for sensitivity to biocides, antibiotics, and other antimicrobial compounds as described below.

Poly- hexamethylen guanidinium hydrochloride PHMG solution containing 7. Growth and sterility controls were included for each isolate. All assays were done in triplicate. From the preliminary screening on antimicrobial resistance, 30 isolates were selected for further study based on food source, antibiotic resistance and biocide tolerance. Selected isolates were resistant to at least three antibiotics or at least to one antibiotic and one biocide.

The 30 isolates were identified by 16S rDNA sequencing. The selected 30 isolates were tested for tolerance to copper and zinc metals as follows. The lowest metal concentration that inhibited growth of the inoculated bacterial strains was taken as the MIC. The selected 30 isolates were investigated for the presence of genetic determinants of resistance. Other antimicrobial resistance genes investigated by PCR were the aminoglycoside resistance genes aadA1 Guerra et al.

The chromosomal cueAR operon, encoding a putative P1-type ATPase and a MerR-type regulatory protein involved in copper homeostasis in Pseudomonas putida was investigated according to Adaikkalam and Swarup The chromate resistance gene chrB was investigated as described by Chihomvu et al.

Positive correlations were defined as very weak 0. The microbial load aerobic mesophiles of the different seafood samples is shown in Table 1. Lowest viable counts were reported for blue shark, and highest counts were found in refrigerated raw salmon slices packed in trays. After viable cell counting, bacterial colonies grown on saline TSA from highest dilutions were repurified by streaking on TSA without added salt.

This was done so in order to avoid possible interference of added salt in growth media with antimicrobial resistance tests. A total of 87 bacterial colonies isolated at random were selected, representing the different seafood products sampled Table 1. Eighty two of them were Gram-negatives including mainly bacilli , while the remaining five were Gram-positive including four cocci and one rod.

The 87 isolates were tested for sensitivity to antibiotics, biocides and other antimicrobials cavacrol, thymol, sodium lactate, trisodium phosphate, lysozyme, and different lysozyme-EDTA combinations; Table 1. Resistance to protein synthesis inhibitors was detected mostly for CM Remarkably, a Two isolates were resistant to 10 out of the 11 antibiotics tested.

Bacterial isolates were tested for biocide tolerance in two groups Gram-positives, and Gram-negatives since Gram-negative bacteria in general have greater tolerance to biocides because of the outer membrane permeability barrier. Only low percentages of the Gram negative isolates showed high tolerance levels to the biocides BC 5. Higher percentages of biocide-tolerant isolates were obtained for CHX A total of seven isolates showed high tolerance to three or more biocides Table 1.

Isolates showed large differences in sensitivities to carvacrol and thymol Table 1. Only two isolates had MICs higher than 0. By contrast, Regarding thymol, There was also a high percentage of isolates However, isolates were more heterogeneous in sensitivity to trisodium phosphate TSP. Most isolates When lysozyme was tested in combination with EDTA at different proportions, all combinations were effective against most isolates, except for one isolate that only was inhibited by lysozyme-EDTA combination C containing a higher proportion of lysozyme to EDTA.

Of the 87 isolates, 66 Comparing biocides and antibiotics, of the 29 isolates tolerant to at least one biocide Six isolates 6.

The correlations between the different antimicrobials tested for the 87 bacterial isolates are shown in Figure 1 and Table 2. Figure 1. Biplot for biocide tolerance and antimicrobial resistance scores in the 87 bacterial isolates variables from seafoods. Antimicrobials A , red dots, and isolates B , blue dots are indicated. In B , the letters indicate the bacterial isolates with an outstanding high number of antimicrobial resistance traits.

Table 2. Correlations between antibiotic resistance and tolerance to biocides and other antimicrobials in the 87 bacterial isolates recovered from seafood.

From the preliminary general study, 30 isolates were selected for further analysis regarding metal resistance, identification, and study of the genetic determinants of resistance. The 30 isolates selected for further study were identified by 16s rDNA sequencing Table 3.

Most of them The only Gram positive isolate identified belonged to Listeria innocua 3. Results obtained on the genetic determinants of resistance for the selected isolates are shown in Table 3.

Twenty seven out of the 30 isolates tested positive for at least one of the genetic determinants studied. It was found in three isolates of A. The genetic determinant for sulfonamide resistance sul1 was detected in 13 isolates, two of which also tested positive for sul2.

In addition, three A. However, PCR experiments using a qacEF primer and a sulR primer did not yield any amplification, suggesting that both genetic determinants were not physically close as in class I integrons. Of the five isolates positive for bla TEM , three belonged to genus Acinetobacter isolated from salmon, one to Aeromonas and one to Pseudmonas. The phenicol resistance determinant floR was detected in five isolates all of them belonging to genus Pseudomonas from different sources: anchovies, black mackerel and sea bass.

By contrast, cmlA was not detected in any isolate. Regarding zinc tolerance, a However, all isolates tested were inhibited by 16 mM ZnCl 2. The remaining metal resistance genes investigated were not detected. In the present study, biocide tolerance and antibiotic resistance were detected among bacteria isolated from seafoods.

Biocides are used for many different purposes, including health care products and in disinfection processes in the food industry. For example, benzalkonium chloride is used for water treatment, general site disinfection, fish parasite removal, and prevention of infectious disease in fish and shellfish. As a result, large amounts of biocides arrive to waters. The impact of triclosan on aquatic bacterial communities has been described Dann and Hontela, ; McNamara et al.

Previous contact with biocides as well as natural background resistance could explain the biocide tolerances observed in the present study. It is also worth noting that there were positive correlations not only for tolerance to biocides of the same chemical group but also between biocides from different groups. However, there were differences between polyguanides, since poly- hexamethylen guanidinium hydrochloride showed positive correlation with several other biocides while chlorhexidine did not.

These results could be explained by differences in chemical formula, mechanisms of adaptation including intrinsic resistance , and also by the development of specific mechanisms of tolerance upon exposure to multiple biocides. Cross-resistance between antibiotics and biocides and between different biocides has been reported for different bacteria, like for example Pseudomonas aeruginosa Lambert et al.

Furthermore, previous studies have shown that adaptation to biocides by repeated exposure results in an increased resistance to antibiotics Gadea et al. For example, the phenolic biocide triclosan showed positive correlation with a lower sensitivity to the phenolic compound thymol but not with carvacrol , and the antibiotic ampicillin also showed positive correlation with thymol.

Previous studies have shown that exposure to plant essential oils which are rich in phenolic compounds such as pine oil resulted in the selection of mutants with deregulated mar operon that had decreased susceptibility to a range of antimicrobial compounds including antibiotics and biocides as a consequence of reduced cell permeability and increased efflux pump activity Moken et al.

It is worth mentioning that the chemical preservatives sodium lactate and trisodium phosphate only showed moderate positive correlations with the antibiotics ampicillin and imipenem, but not with biocides. A recent study indicated that bacteria adapted to quaternary ammonium compounds under laboratory conditions showed a generalized increased tolerance to preservatives such as 4-hydroxybenzoic acid, thyme, and clove oil, sodium, and potassium nitrates, potassium sorbate , while the opposite was observed in the case of triclosan Gadea et al.

In the present study, the sulfonamide resistance sul1 gene was the genetic determinant detected most frequently. Sulfonamide resistance is most often linked to Class I integrons. Remarkably, one study carried out at aquaculture facilities in the northern Baltic Sea Finland reported that antibiotic resistance genes for sulfonamides sul1 and sul2 and trimethoprim dfrA1 and an integrase gene for a class 1 integron intI1 persisted in sediments below fish farms at very low antibiotic concentrations during a 6-year observation period Muziasari et al.

Presumably, antimicrobial resistance genes could spread in marine sediments to other bacteria that colonize non-aquaculture fish and from these to seafood processing environments. This could explain the finding of sul1 in bacteria isolated in the present study from fish like sardines, anchovies, Athlantic horse mackerel, sea bass, gilthead seabream, and salmon, or from squid. Furthermore, in a number of cases, bacterial isolates carrying sul1 also tested positive for the florfenicol resistance gene floR , which can also be associated with Class 1 integrons Toleman et al.

Remarkably, one of the two isolates from the present study with broadest spectra of antimicrobial resistance identified as A. The A. Since the prawns were boiled and frozen and then sold unfrozen over the counter on ice, there is a possibility that this strain arrived to the food by cross contamination during handling. We want to know if and which special combinations of antibiotics and material protection agents can lead to antibiotic-resistant bacteria on surfaces. Left: Medical hoses must be germ-free.

Right: bacteria in the biofilm of a ureteral stent. Many people are dealing with precisely this problem in their everyday work, e.

They must disinfect medical surfaces, equipment or implants, i. But what happens if the remedy only works poorly because an environment has developed in which certain germs can still grow and neither the disinfectant — i. Then it becomes a considerable health risk and a high cost. In addition to interactions on surfaces and the formation of cross-resistance, Frank Schreiber is also interested in learning what happens when biocides are cyclically used on surfaces, as is often the case with things like disinfectants and with applications in industry.

It has been observed that this cyclical use can lead to microorganism populations exposed to this stress developing the very special property where individuals gain a higher stress tolerance. They are more persistent than others and can survive longer.

This phenomenon is called persistence and it has also been described for antibiotics. Persistence is always a first step in developing resistance. Though this remains to be investigated in biocides", says Frank Schreiber. Furthermore, the team is researching the potential for the development and spread of biocide resistance in the environment. Legislators have defined the use of hazardous substances in different regulations.