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  • C12Q1/18—Testing for antimicrobial activity of a material
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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  • C07K14/195—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria
  • C07K14/24—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
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  • C07K5/00—Peptides containing up to four amino acids in a fully defined sequence; Derivatives thereof
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  • C07K5/06—Dipeptides
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  • C07K5/06078—Dipeptides with the first amino acid being neutral and aromatic or cycloaliphatic
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  • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
  • C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides

Definitions

• This invention relates to methods and compositions for manipulating bacterial resistance to non-antibiotic antibacterial compositions, disinfectants and organic solvents.
• Antibiotic or antimicrobial substances have long been used to inhibit the growth of bacteria or other microbes and to treat bacterial or microbial infections in humans, other animals, and in tissue culture.
• the use of antibiotics or antimicrobials in a treatment regimen has the undesirable effect of selecting for bacteria or other microbes which are resistant to those antibiotics or antimicrobials which are administered or applied.
• treatment regimens can be adversely affected or, in some cases, rendered ineffective. This necessitates a continual search for new antibiotics and antimicrobials.
• Bacteria expressing a chromosomal multiple antibiotic resistance phenotype can be isolated by selecting bacteria with a single antibiotic and then screening for cross-resistance to structurally unrelated antibiotics.
• George and Levy initially described a chromosomal multiple antibiotic resistance system which exists in Escherichia coli and which can be selected by a single drug. e.g.. tetracvcline or chloramphenicol (George and Levy, 1983).
• the Mar phenotype includes resistance to structurally unrelated agents, including nalidixic acid, rifampin, penicillins, and cephalosporins (George and Levy 1983) as well as fluoroquinolones (Cohen et al. 1989).
• the chromosomal gene locus which correlates with the Mar phenotype observed in E. coli has been identified.
• the chromosomal mar locus located at 34 min on the E. coli chromosomal map, is involved in the regulation of intrinsic susceptibility to structurally unrelated antibiotics (Cohen et al.. J. Bacteriol. 175: 1484-1492. 1993; Cohen et al.. Aniimicrob.
• the mar locus consists of two transcription units (marC and marRAB) which are divergently transcribed from a central putative operator-promoter region (marO) (Cohen et al., 1993; Goldman et al., 1996).
• marR is the repressor of the marRAB operon (Cohen et al.. 1993; Martin and Rosner. Proc. Natl. Acad. Sci. USA 92:5465-5460, 1995; Seoane and Levy, J. Bacteriol. 177:3414-3419. 1995). Mutations in marR result in increased expression of the marRAB operon. Overexpression o ⁇ marA alone is sufficient to produce the multiple antibiotic resistance phenotype (Cohen et al.. 1993; Gambino et al.. J. Bacteriol.
• mar A confers multiple antibiotic resistance via increased efflux of antibiotics, including fluoroquinolones, tetracycline, and chloramphenicol (Cohen et al., 1989; George and Levy, 1983; McMurry et al., Aniimicrob. Agents Chemother. 38:542-546, 1994).
• Non-antibiotic antibacterial compositions such as disinfectants are widely used in both clinical and consumer environments for reducing bacterial contamination of work surfaces, equipment, products and the like. These non-antibiotic antibacterial compositions have been incorporated into a wide spectrum of cleansers, disinfectant compositions, soaps, lotions, plastics, etc. It is not known whether exposure of bacteria to non-antibiotic antibacterial compositions also can select for bacterial mutants, including those which display a multiple antibiotic resistance phenotype.
• bacterial mutants having multiple antibiotic resistance can be selected by non-antibiotic antibacterial agents such as common disinfectants. It further has been discovered that the phenotype of the multiple antibiotic resistant mutants selected by a non-antibiotic antibacterial agent results from mutations in chromosomal gene loci which regulate expression of efflux pumps, which loci have been implicated in multiple antibiotic resistance phenotypes as described above. The efflux pumps actively pump out the non-antibiotic antibacterial agents, as well as organic solvents and antibiotics, thereby rendering the mutant bacteria resistant to all of the foregoing compounds.
• a method for inhibiting the selection and/or propagation of a bacterial mutant that overexpresses an efflux pump.
• Bacteria are contacted with an agent that binds to a gene locus (the expression of the gene locus enhances expression of the efflux pump) or an expression product thereof, in an amount effective to inhibit the gene locus-enhanced expression of the efflux pump.
• the gene locus is selected from the group consisting of a mar locus, a sox locus and a rob locus.
• the efflux pump is acr-like. including the acrAB efflux pump.
• the agent can be selected from the group consisting of chemicals, antisense nucleic acids, antibodies, ribozymes, and proteins which repress expression of the gene locus.
• a preferred embodiment is an agent that is an antisense nucleic acid, and in particularly preferred embodiments, the agent is antisense to the mar locus, sox locus and/or rob locus.
• Another preferred embodiment is chemical inhibitors of efflux pumps, particularly L-phenylalanyl-L-arginyl- ⁇ -naphthylamide.
• a method for rendering bacterial cells more susceptible to a non-antibiotic bactericidal or bacteriostatic agent that is a substrate of an efflux pump.
• An inhibitor of a gene locus or an expression product thereof is administered to a bacterial cell, wherein the expression of the gene locus enhances expression of an efflux pump.
• the gene locus is selected from the group consisting of a mar locus, a sox locus and a rob locus.
• the efflux pump is ⁇ cr-like and can be acrAB. The preferred inhibitors are as described above.
• a method for rendering bacterial cells more susceptible to a non-antibiotic bactericidal or bacteriostatic agent that is a substrate of an efflux pump.
• the method involves administering to the bacterial cell an inhibitor of the efflux pump.
• the efflux pump is ⁇ cr-like and can be acrAB.
• the inhibitor is selected from the group consisting of about 4% ethanol, methanol. hexane. minocycline and L-phenylalanyl-L-arginyl- ⁇ -naphthylamide.
• a method for modulating (increasing or decreasing) the ability of bacterial cells to survive in an organic solvent.
• the method involves enhancing expression in the bacterial cells of an organic solvent bacterial efflux pump by growing the bacterial cells in the presence of a non-mar/s ox/rob inducing agent, wherein the agent induces the overexpression of the organic solvent bacterial efflux pump.
• the agent can be a gene encoding an ⁇ cr-like pump, the acrAB pump, or expression products thereof.
• the method involves reducing expression in the bacterial cells of an organic solvent bacterial efflux pump by growing the bacterial cells in the presence of an agent, wherein the agent reduces the expression of the organic solvent bacterial efflux pump.
• the agent can be an antisense nucleic acid which binds to a gene locus encoding an ⁇ cr-like pump, especially the acrAB pump, a gene locus which enhances expression of an efflux pump, such as mar A, soxA and rob A. and the like.
• the agent also can be a ribozyme or a protein which represses expression of the gene locus.
• the agent also can be an antibody to an expression product of the foregoing genes.
• the agent also can be a chemical compound which reduces expression of the efflux pump, or reduces activity of the efflux pump, such as L-phenylalanyl-L-arginyl- ⁇ -naphthylamide.
• a method for testing the ability of a non-antibiotic composition to induce a multiple antibiotic resistance phenotype in a bacterium.
• the bacterium is contacted with the non-antibiotic composition.
• the expression of a bacterial gene locus is determined, the altered expression of which is indicative of induction of the multiple antibiotic resistance phenotype in the bacterium.
• the result of this determination is compared with a control, wherein altered expression of the bacterial gene locus indicates that the non- antibiotic composition induces the multiple antibiotic resistance phenotype in the bacterium.
• the gene locus is selected from the group consisting of a mar locus, a sox locus, a rob locus and an ⁇ cr-like efflux pump locus.
• the efflux pump locus is acrAB.
• the foregoing method can be carried out using a non-antibiotic composition that is an inactive ingredient.
• the inactive ingredient can be a non-bactericidal ingredient.
• the inactive ingredient also can be a non-bacteriostatic ingredient.
• a composition is provided.
• the composition includes a non-antibiotic bactericidal or bacteriostatic first agent and a second agent that inhibits the expression of activity of an efflux pump.
• the second agent inhibits the expression of a gene locus or an expression product thereof, wherein the expression of the gene locus enhances expression of the efflux pump.
• the second agent is selected from the group consisting of antisense nucleic acids, antibodies, ribozymes and proteins that repress expression of the gene locus.
• the second agent inhibits an ⁇ cr-like efflux pump, and particularly preferred is an antisense nucleic acid.
• the second agent also can be selected from the group consisting of 4% ethanol, methanol, hexane, minocycline and L-phenylalanyl-L-arginyl- ⁇ -naphthylamide.
• the preferred second agent is [preferred inhibitor].
• the first agent in some embodiments is selected from the group consisting of triclosan, pine oil, quaternary amine compounds including alkyl dimethyl benzyl ammonium chloride, chloroxylenol, triclocarbon, disinfectants and organic solvents.
• Figure 1 shows the Northern blot analysis of marRAB mRNA in bacterial mutants.
• the invention is based on the discovery that non-antibiotic antibacterial compositions and organic solvents select for mutant bacteria which are resistant not only to the non-antibiotic antibacterial compositions, but also to a range of antibiotics (i.e. a multiple antibiotic resistant phenotype) and also to organic solvents. All of the foregoing compounds are pumped out of bacteria by efflux pumps, i.e.. the foregoing compounds are substrates for the efflux pumps. Based on these discoveries it is now possible to enhance the antibacterial properties of non-antibiotic antibacterial compositions and also reduce the selection of bacterial mutants having a multiple antibiotic resistance phenotype by such compositions.
• the invention also provides methods for testing the ability of non-antibiotic antibacterial compositions to select for or induce a multiple antibiotic resistance phenotype in bacteria.
• the invention also provides methods for increasing or decreasing bacterial tolerance to organic solvents by increasing or decreasing the activity of bacterial organic solvent efflux pumps, such as by increasing or decreasing expression of an efflux pump, increasing or decreasing expression of genes which positively regulate efflux pump gene loci, and the like.
• Compositions useful in the foregoing methods are also provided.
• a non-antibiotic antibacterial composition is a molecule or combination of molecules which are bactericidal or bacteriostatic, but which are not antibiotics.
• Antibiotics are those bactericidal or bacteriostatic compounds which are administered in vivo to people, animals or plants which have a bacterial infection, or which are used in vitro for research on bacterial infections of animals.
• a non-antibiotic antibacterial composition is not administered to a subject, but rather is used as a disinfectant for killing bacteria or reducing the growth rate of a population of bacteria.
• Non-antibiotic antibacterial compositions are added as the active ingredients in a variety of industrial and household disinfectants, such as LYSOLTM, PINE-SOLTM, and the like.
• Non-antibiotic antibacterial compositions also are added as the antibacterial active ingredient in non-disinfectant compositions such as soaps, lotions, cleansers and the like. More recently, non-antibiotic antibacterial composition have been incorporated into plastics for making a variety of articles of manufacture which have resistance to bacterial growth.
• the non-antibiotic antibacterial compositions may have active and inactive ingredients.
• the active ingredients are, of course, the bactericidal or bacteriostatic agents which have the effect of slowing or stopping growth of populations of bacteria, or even killing such populations of bacteria.
• Active bactericidal or bacteriostatic ingredients include triclosan, pine oil, quaternary amine compounds such as alkyl dimethyl benzyl ammonium chloride, chloroxylenol. triclocarbon, and other well known disinfectants.
• the inactive ingredients are the balance of the components of the non-antibiotic antibacterial compositions, including surfactants and other cleansing agents, binders, bulking agents and other compounds.
• non-antibiotic antibacterial compositions refers both to the active ingredient of the compositions as well as the compositions themselves.
• the invention provides methods for inhibiting the selection or propagation of a bacterial mutant that overexpresses an efflux pump.
• inhibiting the selection or propagation it is meant that the method provides inhibition of selection of a multiple antibiotic resistant bacterial mutant (i.e.. the initial mutation event which causes the induction of an efflux pump) and/or inhibition of propagation of a multiple antibiotic resistant bacterial mutant (i.e.. growth and/or replication of such bacteria).
• the invention also provides methods for rendering bacterial cells more susceptible to non-antibiotic antibacterial compositions by administering to the bacterial cells inhibitors of an efflux pump or a gene locus which enhances expression of the efflux pump, or an expression product thereof.
• administered to it is meant that the bacterial cells are contacted with the inhibitor for a time sufficient to permit inhibition of the efflux pump or gene locus.
• the invention further provides methods for increasing or decreasing organic solvent tolerance of bacterial cells.
• overexpression of an organic solvent efflux pump is induced or decreased by growing the cells in the presence of an agent.
• induced “overexpression” it is meant that the organic solvent efflux pump is expressed at a higher level in bacterial cells grown in the presence of an inducing agent than in identical bacterial cells grown under identical conditions but without the agent, i.e.. a level of expression that is sufficient to increase organic solvent tolerance.
• organic solvent efflux pump is expressed at a lower level in bacterial cells grown in the presence of an inhibiting agent than in identical bacterial cells grown under identical conditions but without the agent, i.e., a level of expression that is sufficient to reduce tolerance or increase organic solvent susceptibility.
• These methods can also confer organic solvent tolerance or susceptibility by modulating the activity of an efflux pump as described herein.
• Organic solvent tolerance or susceptibility can be determined by standard methodologies, including those exemplified in Example 2 below.
• non-antibiotic antibacterial products are the reduction in bacterial populations in those products or on those products, or on surfaces to which such products are applied.
• non-antibiotic antibacterial products also can select for multiple antibiotic resistant bacteria. It would be useful to be able to determine which non-antibiotic antibacterial compositions select for deleterious mutants. Having determined that non-antibiotic antibacterial compositions can select for mutants, it is also possible that other non-antibiotic compositions can select for mutations. Therefore the invention embraces methods for testing the ability of non-antibiotic compositions to induce a multiple antibiotic resistance phenotype. These methods permit testing of any non-antibiotic composition, including the inactive ingredients in cleansers, soaps, disinfectants and the like.
• a bacterial culture is contacted with a non- antibiotic composition and the expression of a gene locus which is indicative of a multiple antibiotic resistant phenotype is determined.
• the gene locus expression can be determined by any convenient method, of which many are known in the art. These methods include enzyme assays comprising fusions of regulatory loci to a marker gene (e.g. as described for a mar regulatory locus in PCT published application W094/05810), amplification of gene transcripts (such as using polymerase chain reaction), hybridization methods including Northern blots, and measurement of protein expression including Western blots. ELISA. etc. The level of expression of the gene locus is then compared with a control to determine if the non-antibiotic compositions induced the multiple antibiotic resistant phenotype.
• various agents which inhibit the expression or activity of an efflux pump or gene loci which control expression of the efflux pump are useful for reducing selection and/or propagation of mutant bacteria, and also render the cells more susceptible to non-antibiotic antibacterial compositions.
• These inhibitors are contacted with or administered to the bacterial cells to prevent the undesirable effects of the non-antibiotic antibacterial compositions.
• One convenient way to ensure contact of the appropriate bacterial cell populations is to include the inhibitors and agents in the non-antibiotic antibacterial compositions.
• the invention further provides compositions comprising a non-antibiotic bactericidal or bacteriostatic first agent and a second agent which inhibits the expression or activity of an efflux pump, as described above.
• compositions can be prepared according to the standard procedures used to prepare non-antibiotic antibacterial compositions.
• a standard disinfectant composition such as PINE-SOLTM can have added to it an effective amount of an inhibitor of an efflux pump such as described in PCT published patent application W096/33285, or an antisense nucleic acid which binds to the efflux pump gene locus, etc.
• an effective amount is meant an amount of the second agent which reduces the selection of mutants by the non-antibiotic first agent. Effective amounts can be determined using standard bacterial growth and mutation assays, including those provided herein. For example, various amounts of the second agent can be added to a non-antibiotic antibacterial composition, and the combined composition can be used as provided in the examples below to select bacterial mutants. Any amount of the second agent which reduces the number of mutants selected relative to the number of mutants selected by the non-antibiotic antibacterial composition alone is an effective amount.
• One of ordinary skill in the art can determine with no more than routine experimentation what constitutes an effective amount of a second agent, and what amount of a second agent is optimal to prevent selection of mutants by the non-antibiotic antibacterial compositions. Effective amounts of other inhibitors and agents disclosed herein can be determined similarly.
• inhibitors of the marA gene locus and other loci which regulate efflux pumps are effective to reduce the selection of antibiotic resistant bacterial mutants by non-antibiotic antibacterial compositions, and also potentiate the antibacterial properties of such compositions.
• the marA gene has been cloned and sequenced. the sequence deposited as GenBank accession number M96235.
• the marA gene has homologs in E. coli. as well as in other species of bacteria. Inhibitors of such marA homologs also are useful for reducing the selection of antibiotic resistant bacterial mutants and potentiating the antibacterial properties of non-antibiotic antibacterial compositions.
• the MarA protein is homologous to both SoxS. the effector of the s ⁇ xRS regulon (Fawcett and Wolf. Mol. Microbiol. 14:669-679, 1994; Li and Demple. J. Biol. Chem. 269: 18371 - 18377. 1994), and RobA. a small protein that binds to the E. coli replication origin and some stress gene promoters (Ariza et al.. 1995; Cohen et al., 1995; Jair et al.. J. Bacteriol. 178:2507-2513, 1996; Skarstad et al.. J. Biol. Chem. 268:5365-5370. 1993).
• soxRS regulon mediates the cell's response to oxidative stress (Amabile-Cuevas and Demple. Nucleic Acids Res. 19:4479-4484, 1991 ; Nunoshiba et al.. J. Bacteriol. 174:6054-6060. 1992; Wu and Weiss. J. Bacteriol. 173:2864-2871 , 1991 ).
• sox S genes include those found in S. typhimurium (GenBank accession number U61 147) and E. coli (GenBank accession numbers X59593 and M601 1 1).
• rob A genes include those found in E. coli (GenBank accession numbers AE000509. U00096. M97495 and M94042).
• marA homologs of marA include those found in Enter obacteriaceae by nucleic acid hybridization under stringent conditions (Cohen et al., 1993).
• marA homologs include pqrA, identified in Proteus vulgaris (GenBank accession number D 13561), ramA identified in Klebsiella pneumonia (GenBank accession number U 19581 ), and aarP identified in Providencia stuartil (GenBank accession number L38718).
• Additional homologs of marA can be identified by conventional techniques. Such techniques include cloning by hybridization to marA or to known homologs thereof, and functional cloning. Cloning by hybridization involves subjecting marA or known homologs thereof to hybridization with nucleic acids of bacteria (preferably the chromosomal DNA) under stringent conditions.
• stringent conditions refers to parameters with which the art is familiar. Nucleic acid hybridization parameters may be found in references which compile such methods, e.g. Molecular Cloning: A Laborator Manual, J. Sambrook, et al.. eds.. Second Edition. Cold Spring Harbor Laboratory Press, Cold Spring Harbor. New York, 1989.
• stringent conditions refers, for example, to hybridization at 65°C in hybridization buffer (3.5 x SSC. 0.02% Ficoll, 0.02% polyvinyl pyrrolidone, 0.02% Bovine Serum Albumin. 2.5mM NaH 2 PO 4 (pH7). 0.5% SDS. 2mM EDTA).
• SSC is 0.15M sodium chloride/0.15M sodium citrate. pH7; SDS is sodium dodecyl sulphate; and EDTA is ethylenediaminetetracetic acid.
• the membrane upon which the DNA is transferred is washed at 2 x SSC at room temperature and then at 0.1 x SSC/0.1 x SDS at temperatures up to 65°C.
• homologs typically will share at least 30% nucleotide identity and or at least 40% amino acid identity to mar/sox/rob genes or to efflux pumps genes, or their polypeptide products respectively, in some instances will share at least 50% nucleotide identity and/or at least 65% amino acid identity and in still other instances will share at least 60% nucleotide identity and/or at least 75% amino acid identity.
• Watson-Crick complements of the foregoing nucleic acids also are embraced by the invention.
• Functional cloning is useful to isolate homologs which do not share sufficient homology at the nucleotide or amino acid sequence level to permit cloning by nucleic acid hybridization, but which nevertheless are functional equivalents of the genes useful in the invention. Functional equivalents need not exhibit the same level of activity, merely activity of the same kind. For example, one phenotypic manifestation of marA expression is the induction of the expression of a set of genes, including acrA. A gene which induces substantially the same set of genes but at a lower level of expression would be considered a functional equivalent.
• Functional cloning involves expression of a nucleic acid sequence in a bacterium and determining whether the expression of that sequence confers a desired phenotype on the bacterium. It is known that marA homologs exhibit similar functional characteristics with respect to multiple antibiotic resistance phenotype. For example, overexpression of either soxS or robA in E coli produces both increased organic solvent tolerance and low-level resistance to multiple antimicrobial agents (A ⁇ za et al.. J. Bacteriol 177 1665-1661. 1995; Nakajima et al.. Biosci Biotechnol Biochem 59.1323-1325. 1995a: Nakajima et A..
• the desired phenotype can be multiple antibiotic resistance, induction of w ⁇ r-regulated genes (see, e.g., U.S. Patent 5.650,321), and the like.
• marA homologs can be expressed according to standard procedures, such as transformation with an expression plasmid containing the marA homolog.
• the acrAB locus positively regulated by MarA. (Ma et al . Mol Microbiol 16 45-55. 1995) and SoxS and RobA (Ma et al., Mol Microbiol 19: 101-1 12, 1996). specifies a proton-motive-torce-dependent multidrug efflux pump for a wide variety of mostly lipophihc substances (Ma et al., 1995; Nikaido. Bacteriol 178:5853- 5859, 1996; Nikaido, Science 264.382-387. 1994, Paulsen et al .
• Sequence homologs of acrAB efflux pumps are referred to herein as " ⁇ cr-like" efflux pumps. Isolation of ⁇ cr-hke efflux pumps and other efflux pumps can be earned out according to the methods described above for nucleic acid hybridization and functional cloning. Inhibitors of such acrAB homologs also are useful for reducing the selection of antibiotic resistant bacterial mutants and potentiating the antibacterial properties of non- antibiotic antibacterial compositions.
• Agents which induce overexpression of ⁇ cr-hke efflux pumps are useful in promoting organic solvent tolerance.
• Inducers of efflux pumps include genes which encode the vanous efflux pumps which when expressed in a bacterium as a nucleic acid operably linked to a promoter can increase the numbers of efflux pump protein molecules in the bacterium.
• Agents also include molecules which inhibit the function of efflux pump regulatory genes. For example, antisense nucleic acids which bind to acrR and prevent its transcription or translation would function as inducers of acrAB.
• Efflux pumps can also be induced by mutation of regulatory genes (such as acrR for the acrAB pump).
• Agents useful in decreasing the expression or activity of an efflux pump for increasing organic solvent susceptibility are provided in the following paragraphs.
• Agents which bind to a gene locus which mediates enhanced expression of an efflux pump (such as the mar/sox/rob class of genes) or a nucleic acid expression product thereof include antisense nucleic acids, ribozymes and regulatory proteins such as repressor proteins (e.g. MarR).
• antisense nucleic acids which bind to marA and prevent transcription or translation thereof would function as inhibitors of marA and agents which bind marA.
• Agents which bind to a protein expression product of a gene locus include antibodies.
• Inhibitors of the foregoing gene loci and expression products also include molecules which bind to the gene loci and expression products as described above. Other classes of agents and inhibitors of these types will be known to those of skill in the art.
• inhibitors include ethanol (concentrations of about 4%). methanol. hexane and minocycline.
• Still other inhibitors include antisense nucleic acids and ribozymes directed against the gene(s) encoding the efflux pump.
• antisense nucleic acids which bind to acrAB genes and prevent transcription or translation thereof would function as inhibitors o ⁇ acrAB.
• Antibodies which bind efflux pumps or proteins which, regulate the expression of efflux pumps are another class of inhibitors.
• Still other inhibitors include genes which repress expression of the efflux pumps or regulatory loci (such as marR) which regulate expression of efflux pumps. Increasing the amount of such genes or the expression products thereof reduces the expression of efflux purnps in bacteria.
• the invention embraces antisense nucleic acids, including oligonucleotides. that selectively bind to a nucleic acid molecule encoding an efflux pump (e.g. acrA) or a molecule which regulates expression of an efflux pump (e.g. marA).
• an efflux pump e.g. acrA
• a molecule which regulates expression of an efflux pump e.g. marA
• antisense oligonucleotide or “antisense” describes an oligonucleotide that is an oligoribonucleotide. oligodeoxyribonucleotide.
• modified oligoribonucleotide or modified oligodeoxyribonucleotide which hybridizes under physiological conditions to DNA comprising a particular gene or to an RNA transcript of that gene and. thereby, inhibits the transcription of that gene and/or the translation of that RNA.
• the antisense molecules are designed so as to interfere with transcription or translation of a target gene upon hybridization with the target gene or transcript. Those skilled in the art will recognize that the exact length of the antisense oligonucleotide and its degree of complementarity with its target will depend upon the specific target selected, including the sequence of the target and the particular bases which comprise that sequence.
• the antisense oligonucleotide be constructed and arranged so as to bind selectively with the target under physiological conditions, i e., to hybridize substantially more to the target sequence than to any other sequence in the target cell under physiological conditions.
• the antisense oligonucleotide should comprise at least 10 and.
• the antisense ohgonucleotides comprise a complementary sequence of 20-30 bases.
• ohgonucleotides may be chosen which are antisense to any region of the gene or RNA transcripts, in preferred embodiments the antisense ohgonucleotides correspond to N-terminal or 5' upstream sites such as translation initiation, transcription initiation or promoter sites. In addition.
• the antisense ohgonucleotides of the invention may be composed of "natural" deoxyribonucleotides, ribonucleotides, or any combination thereof. That is, the 5' end of one native nucleotide and the 3' end of another native nucleotide may be covalently linked, as in natural systems, via a phosphodiester internucleoside linkage. These ohgonucleotides may be prepared by standard methods which may be carried out manually or by an automated synthesizer. They also may be produced recombinantly by vectors.
• the antisense ohgonucleotides of the invention also may include "modified" ohgonucleotides. That is. the ohgonucleotides may be modified in a number of ways which do not prevent them from hybridizing to their target but which enhance their stability or targeting or which otherwise enhance their therapeutic effectiveness.
• modified oligonucleotide as used herein describes an oligonucleotide in which (1) at least two of its nucleotides are covalently linked via a synthetic internucleoside linkage (i.e.. a linkage other than a phosphodiester linkage between the 5' end of one nucleotide and the 3' end of another nucleotide) and/or (2) a chemical group not normally associated with nucleic acids has been covalently attached to the oligonucleotide.
• Preferred synthetic internucleoside linkages are phosphorothioates. alkylphosphonates. phosphorodithioates, phosphate esters, alkylphosphonothioates, phosphoramidates. carbamates, carbonates, phosphate triesters. acetamidates. carboxymcthyl esters and peptides.
• modified oligonucleotide also encompasses ohgonucleotides with a covalently modified base and or sugar.
• modified ohgonucleotides include ohgonucleotides having backbone sugars which are covalently attached to low molecular weight organic groups other than a hydroxyl group at the 3' position and other than a phosphate group at the 5' position.
• modified ohgonucleotides may include a 2'-0-alkylated ribose group.
• modified ohgonucleotides may include sugars such as arabinose instead of ribose.
• the present invention contemplates preparations containing modified antisense molecules that are complementary to and hybridizable with, under physiological conditions, nucleic acids encoding mar/sox/rob or efflux pump polypeptides. together with one or more carriers.
• the invention further embraces the use of antibodies or fragments of antibodies having the ability to selectively bind to efflux pumps, as well as polypeptides which regulate the expression of efflux pumps.
• Antibodies include polyclonal and monoclonal antibodies, prepared according to conventional methodology.
• an antibody from which the pFc' region has been enzymatically cleaved, or which has been produced without the pFc' region designated an F(ab') 2 fragment
• an antibody from which the Fc region has been enzymatically cleaved, or which has been produced without the Fc region designated an Fab fragment
• Fab fragments consist of a covalently bound antibody light chain and a portion of the antibody heavy chain denoted Fd.
• the Fd fragments are the major determinant of antibody specificity (a single Fd fragment may be associated with up to ten different light chains without altering antibody specificity) and Fd fragments retain epitopebinding ability in isolation. Any of the foregoing antigen fragments are useful in the methods and compositions of the invention.
• the present invention also includes so-called single chain antibodies and intracellular antibodies.
• Pine oil is a disinfectant used in products designed for household use. The possibility that such products might select for antibiotic resistance was investigated. In initial studies of a formulation whose active ingredient was pine oil, mutant colonies of Escherichia coli sometimes grew within the zone of inhibition surrounding a 6 mm absorbent paper disc impregnated with the product and placed upon a bacterial lawn. These and other pine oil-resistant mutants were tested for resistance to multiple antibiotics, and the genetic basis for the observed phenotype was examined.
• Mutants resistant to Pine-Sol/pine oil were obtained from stationary phase LB broth cultures of E. coli strain "W ⁇ C” (wild type strain 15-5068 from Carolina Biological Supply Co.. Burlington. NC) and AG100 (George and Levy. J. Bacteriol. 155:531-540. 1983), at 30°C on nutrient agar (NP3.5GP) or LB agar with 2-3 days * incubation in a variety of ways: using the 6mm disc method: plating cells on plates or gradient plates (Curiale and Levy, ./. Bacteriol. 151 :209-215, 1982). containing PIN ⁇ - SOLTM (product of Clorox Co..
• Antibiotic susceptibility was measured at 30°C using antibiotic susceptibility discs (Carolina Biological), gradient plates with the drug in the top agar (Curiale and Levy, 1982), or agar dilution plates (concentration steps of 1.5 fold; inocula of 10 5 cells/ 5 , ⁇ l spot).
• Mutant NP3.5GP, selected on Pine-Sol from strain W ⁇ C. was more resistant than the parent strain to tetracycline, ampicillin, and chloramphenicol (Table 1 A). Nalidixic acid was included in further tests of 1 1 independent mutants from strain AG100.
• PS Pine-Sol
• Ap ampicillin
• Cm chloramphenicol
• the marCORAB locus was deleted in the Pine-Sol/pine oil mutants and in AG102 by P I transduction (Maritime and Curtiss, p.317-347. In Gerhardt et al. eds.. Methods for General and Molecular Bacteriology. American Society for Microbiology. Washington. D. C. 1994) using AG 100/Kan (Maneewannakul and Levy. 1996) as the donor strain and selecting on kanamycin. The deletion caused a 60-70% reduction in the resistance of mutants to Pine-Sol (Table 2 ), down to approximately a wild type level. The same was true for mutant NP3.5GP (data not shown).
• a Relative MIC is the MIC of the inactivated strain divided by the MIC of the strain before inactivation. Values in bold face indicate notable increases in susceptibility. Values obtained from both gradient plate and agar dilution experiments were averaged.
• mutant API did not overexpress soxRS (data not shown: the probe was a 432 bp Ec ⁇ RI-H/ lII fragment from pSXS (Amabile-Cuevas and Demple. Nucleic Acids Res. 19:4479-4484, 1991 ), and the constitutive overexpressing strain JTG1078 (Greenberg et al., 1991) was a positive control).
• this mutant may have a mutation in rob; alternately it may have a mutation in acrR (leading to overexpression of acrAB [Okusu et al., 1996]) that requires that the wild type mar, sox and rob loci be intact for the full resistance phenotype.
• Pine-Sol/pine oil and Mar mutants showed no resistance to household disinfectants containing hydrogen peroxide, hypochlorite, alkyl dimethyl benzyl ammonium chloride (a quaternary amine). or chloroxylenol (a phenol) as their active ingredients (data not shown).
• E. coli strains Bacterial strains and plasmids.
• the E. coli strains, plasmids. and their relevant properties are listed in Table 3. Unless otherwise noted, bacteria were grown and maintained at 30°C in LB broth or LB agar plates with or without the appropriate antibiotics for selection.
• E coli strains AG100-A. AG 100-B, and AG102-A were kindly provided by H. Nikaido (Okusu et al.. J. Bacteriol. 178:306-308, 1996).
• pSRob 926-bp Sall-Sacl fragment Ariza et al. 1 95 containing the entire rob gene from pBt35-13 inserted into pSE380.
• Plasmid DNA was prepared using the Promega WizardTM Prep Kit (Madison. WI). Restriction endonucleases and T4 DNA ligase were purchased from New England Biolabs (Beverly, MA) and used under conditions suggested by the supplier.
• PCR amplification was carried out using the Perkin Elmer Cetus DNA thermal cycler 480. Ta polymerase and reagents were provided by Perkin Elmer Cetus and used as directed. Primers were created which flanked the coding sequence and allowed amplification of marAB ( 1893-2592 bp of the published sequence, Cohen et al.. J: Bacteriol. 175: 1484-1492. 1993). This PCR amplicon was approximately 699 bp in size.
• Organic solvent tolerance assays Organic solvent tolerance of bacterial strains grown to late logarithmic phase was measured in cultures diluted to a concentration of approximately 10 7 cells/ml. A 5 ⁇ l aliquot of the bacterial suspension was plated on LB agar and allowed to dry. An organic solvent was overlaid to a depth of 2-3 mm. The plate was sealed and incubated overnight at 30°C (Aono et al.. Biosci. Biotech. Biochem. 59:213-218, 1995). Cyclohexane. ⁇ -hexane or /7-pentane were used as organic solvents. IPTG was added to the agar plates at a concentration of 0.5 mM when induction of plasmid genes was required.
• EOP efficiency of plating experiments
• the organic solvent tolerance of the E. coli K-12 strain AG100 was compared to an isogenic strain that constitutively expressed the mar operon due to a mutation in marR
• DJ901 pSRob ++ ++ a (- u +) signifies confluent growth; (+)v ⁇ s ⁇ ble growth( ⁇ 100 colonies); (-) signifies no growth.
• IPTG was added to plates at a concentration of 0.5mM when induction of plasmid genes was required (pSE380 derivatives).
• c Values in parenthese are log Pow
• Control LB and cyclohexane layered LB agar plates are averages of two plates
• EOP ⁇ Efficiency of plating experiment

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