'''Antibiotic resistance''' is the ability of a [[microorganism]] to withstand the effects of an [[antibiotic]]. It is a specific type of [[drug resistance]]. Antibiotic resistance evolves naturally via [[natural selection]] through random [[mutation]], but it could also be engineered by applying an evolutionary stress on a population. Once such a [[gene]] is generated, bacteria can then transfer the genetic information in a horizontal fashion (between individuals) by [[plasmid]] exchange. If a bacterium carries several resistance genes, it is called '''multiresistant''' or, informally, a '''superbug'''.
Antibiotic resistance can also be introduced artificially into a microorganism through [[transformation (genetics)|transformation]] protocols. This can be a useful way of implanting artificial genes into the microorganism.
<!--More detail needed-->
==Causes==
[[Image:Antibiotic resistance.svg|thumb|size=180px|right|Schematic representation of how antibiotic resistance evolves via natural selection. The top section represents a population of bacteria before exposure to an antibiotic. The middle section shows the population directly after exposure, the phase in which selection took place. The last section shows the distribution of resistance in a new generation of bacteria. The legend indicates the resistance levels of individuals.]]
Antibiotic resistance is a consequence of [[evolution]] via [[natural selection]]. The antibiotic action is an environmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspring, which will be a fully resistant generation.
Several studies have demonstrated that patterns of antibiotic usage greatly affect the number of resistant organisms which develop. Overuse of [[broad-spectrum antibiotic]]s, such as second- and third-generation [[cephalosporin]]s, greatly hastens the development of '''[[methicillin]]''' resistance. Other factors contributing towards resistance include incorrect diagnosis, unnecessary prescriptions, improper use of antibiotics by patients, and the use of antibiotics as livestock food additives for growth promotion.
Researchers have recently demonstrated the bacterial protein [[LexA]] may play a key role in the acquisition of bacterial mutations.<ref name="pmid15869329">{{cite journal |author=Cirz RT, Chin JK, Andes DR, de Crécy-Lagard V, Craig WA, Romesberg FE |title=Inhibition of mutation and combating the evolution of antibiotic resistance |journal=PLoS Biol. |volume=3 |issue=6 |pages=e176 |year=2005 |pmid=15869329 |doi=10.1371/journal.pbio.0030176 |url=http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030176}}</ref>
==Mechanisms==
The four main mechanisms by which microorganisms exhibit resistance to antimicrobials are:
# Drug inactivation or modification: e.g. enzymatic deactivation of [[Penicillin|''Penicillin'' G]] in some penicillin-resistant bacteria through the production of [[Beta-lactamases|β-lactamases]].
# Alteration of target site : e.g. alteration of [[Penicillin binding protein|PBP]]—the binding target site of penicillins—in [[MRSA]] and other penicillin-resistant bacteria.
# Alteration of metabolic pathway: e.g. some [[sulfa drugs|sulfonamide]]-resistant bacteria do not require [[para-aminobenzoic acid]] (PABA), an important precursor for the synthesis of [[folic acid]] and [[nucleic acids]] in bacteria inhibited by sulfonamides. Instead, like mammalian cells, they turn to utilizing preformed folic acid.
# Reduced drug accumulation: by decreasing drug [[Semipermeable membrane|permeability]] and/or increasing active [[efflux]] (pumping out) of the drugs across the cell surface.
==Resistant pathogens==
''[[Staphylococcus aureus]]'' (colloquially known as "Staph aureus" or a ''Staph infection'') is one of the major resistant pathogens. Found on the [[mucous membranes]] and the [[skin]] of around a third of the population, it is extremely adaptable to antibiotic pressure. It was the first bacterium in which [[penicillin]] resistance was found—in 1947, just four years after the drug started being mass-produced. [[Methicillin]] was then the antibiotic of choice, but has since been replaced by [[oxacillin]] due to significant kidney toxicity. MRSA ([[Methicillin-resistant Staphylococcus aureus|methicillin-resistant ''Staphylococcus aureus'']]) was first detected in Britain in 1961 and is now "quite common" in hospitals. MRSA was responsible for 37% of fatal cases of [[blood poisoning]] in the [[United Kingdom|UK]] in 1999, up from 4% in 1991. Half of all ''S. aureus'' infections in the [[United States|US]] are resistant to penicillin, methicillin, [[tetracycline]] and [[erythromycin]].
This left [[vancomycin]] as the only effective agent available at the time. However, VRSA ([[Vancomycin-resistant Staphylococcus aureus|Vancomycin-resistant ''Staphylococcus aureus'']]) was first identified in Japan in 1996, and has since been found in hospitals in England, France and the US. VRSA is also termed GISA (glycopeptide intermediate ''Staphylococcus aureus'') or VISA (vancomycin insensitive ''Staphylococcus aureus''), indicating resistance to all [[Glycopeptide antibiotic|glycopeptide]] antibiotics.
A ''new'' class of antibiotics, [[Linezolid|oxazolidinone]]s, became available in the 1990s, and the first commercially available oxazolidinone, [[linezolid]], is comparable to vancomycin in effectiveness against MRSA. Linezolid-resistance in ''[[Staphylococcus aureus]]'' was reported in 2003.
CA-MRSA (Community-acquired MRSA) has now emerged as an epidemic that is responsible for rapidly progressive, fatal diseases including necrotizing pneumonia, severe sepsis and necrotizing fasciitis.<ref name="pmid17146447">{{cite journal |author=Boyle-Vavra S, Daum RS |title=Community-acquired methicillin-resistant Staphylococcus aureus: the role of Panton-Valentine leukocidin |journal=Lab. Invest. |volume=87 |issue=1 |pages=3–9 |year=2007 |pmid=17146447 |doi=10.1038/labinvest.3700501}}</ref> Methicillin-resistant ''[[Staphylococcus aureus]]'' ([[MRSA]]) is the most frequently identified antimicrobial drug-resistant pathogen in US hospitals. The [[epidemiology]] of infections caused by MRSA is rapidly changing. In the past 10 years, infections caused by this organism have emerged in the community. The 2 MRSA clones in the United States most closely associated with community outbreaks, USA400 (MW2 strain, ST1 lineage) and USA300, often contain [[Panton-Valentine leukocidin]] (PVL) genes and, more frequently, have been associated with skin and soft tissue infections. Outbreaks of community-associated (CA)-MRSA infections have been reported in correctional facilities, among athletic teams, among military recruits, in newborn nurseries, and among active [[Homosexuality|homosexual]] men. CA-MRSA infections now appear to be endemic in many urban regions and cause most CA-S. aureus infections.<ref name="pmid17479885">{{cite journal |author=Maree CL, Daum RS, Boyle-Vavra S, Matayoshi K, Miller LG |title=Community-associated methicillin-resistant Staphylococcus aureus isolates causing healthcare-associated infections |journal=Emerging Infect. Dis. |volume=13 |issue=2 |pages=236–42 |year=2007 |pmid=17479885 |doi= |url=http://www.cdc.gov/eid/content/13/2/236.htm?s_cid=eid236_e}}</ref>
''[[Enterococcus|Enterococcus faecium]]'' is another superbug found in hospitals. [[Penicillin-Resistant Enterococcus]] was seen in 1983, [[Vancomycin-Resistant Enterococcus]] (VRE) in 1987, and [[Linezolid-Resistant Enterococcus]] (LRE) in the late 1990s.
''[[Streptococcus pyogenes]]'' (Group A Streptococcus: GAS) infections can usually be treated with many different antibiotics. Early treatment may reduce the risk of death from invasive group A streptococcal disease. However, even the best medical care does not prevent death in every case. For those with very severe illness, supportive care in an intensive care unit may be needed. For persons with necrotizing fasciitis, surgery often is needed to remove damaged tissue.<ref>{{cite web |author=Division of Bacterial and Mycotic Diseases |title=Group A Streptococcal (GAS) Disease (strep throat, necrotizing fasciitis, impetigo) -- Frequently Asked Questions |url=http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupastreptococcal_g.htm |date=October 11, 2005 |publisher=Centers for Disease Control and Prevention |accessdate=2007-12-11}}</ref> Strains of ''S. pyogenes'' resistant to [[macrolide]] antibiotics have emerged, however all strains remain uniformly sensitive to [[penicillin]].<ref name="pmid15109426">{{cite journal |author=Albrich WC, Monnet DL, Harbarth S |title=Antibiotic selection pressure and resistance in Streptococcus pneumoniae and Streptococcus pyogenes |journal=Emerging Infect. Dis. |volume=10 |issue=3 |pages=514–7 |year=2004 |pmid=15109426 |doi= |url=http://www.cdc.gov/ncidod/eid/vol10no3/03-0252.htm}}</ref>
Resistance of ''[[Streptococcus pneumoniae]]'' to penicillin and other beta-lactams is increasing worldwide. The major mechanism of resistance involves the introduction of mutations in genes encoding penicillin-binding proteins. Selective pressure is thought to play an important role, and use of beta-lactam antibiotics has been implicated as a risk factor for infection and colonization. Streptococcus pneumoniae is responsible for [[pneumonia]], [[bacteremia]], [[otitis media]], [[meningitis]], [[sinusitis]], [[peritonitis]] and [[arthritis]].<ref name="pmid15109426">{{cite journal |author=Albrich WC, Monnet DL, Harbarth S |title=Antibiotic selection pressure and resistance in Streptococcus pneumoniae and Streptococcus pyogenes |journal=Emerging Infect. Dis. |volume=10 |issue=3 |pages=514–7 |year=2004 |pmid=15109426 |doi= |url=http://www.cdc.gov/ncidod/eid/vol10no3/03-0252.htm}}</ref>
''Proteus'' can cause urinary tract infections and hospital-acquired infections. ''Proteus'' is unique, however, because it is highly motile and does not form regular colonies. Instead, ''Proteus'' forms what are known as "swarming colonies" when plated on non-inhibitory media. The most important member of this genus is considered to be ''[[Proteus mirabilis]]'', a cause of wound and urinary tract infections. Fortunately, most strains of ''Proteus mirabilis'' are sensitive to ampicillin and cephalosporins. Unlike its relative, ''[[Proteus vulgaris]]'' is not sensitive to these antibiotics. However, this organism is isolated less often in the laboratory and usually only targets immunosuppressed individuals. ''Proteus vulgaris'' occurs naturally in the intestines of humans and a wide variety of animals; also manure, soil and polluted waters. More than 80% of human [[urinary tract infections]] (UTI) are due to the bacterium ''[[Escherichia coli]]'' but urinary infections due to ''Proteus mirabilis'' are also well documented. ''Proteus mirabilis'' once attached to urinary tract, infects the kidney more commonly than ''E. coli''. ''Proteus mirabilis'' belongs to family Enterobacteriaceae and is a gram-negative motile swarmer bacterium. ''Proteus mirabili''s are often found as free-living organisms in soil and water but they are also parasitic in the upper urinary tract of human beings.
Penicillin-resistant [[pneumonia]] caused by ''[[Streptococcus pneumoniae]]'' (commonly known as ''pneumococcus''), was first detected in 1967, as was penicillin-resistant [[gonorrhea]]. Resistance to penicillin substitutes is also known as beyond ''S. aureus''. By 1993 ''[[Escherichia coli]]'' was resistant to five [[quinolones|fluoroquinolone]] variants. ''[[tuberculosis|Mycobacterium tuberculosis]]'' is commonly resistant to [[isoniazid]] and [[rifampin]] and sometimes universally resistant to the common treatments. Other pathogens showing some resistance include ''[[Salmonella]]'', ''[[Campylobacter]]'', and ''[[Streptococci]]''.
In November 2004, the [[Centers for Disease Control and Prevention]] (CDC) reported an increasing number of ''[[Acinetobacter baumannii]]'' bloodstream infections in patients at military medical facilities in which service members injured in the [[Iraq]]/[[Kuwait]] region during [[Iraq war|Operation Iraqi Freedom]] and in [[Afghanistan]] during [[Operation Enduring Freedom]] were treated. Most of these showed [[multidrug resistance]] (MRAB), with a few isolates resistant to all drugs tested.<ref name="pmid15549020">{{cite journal |author= |title=Acinetobacter baumannii infections among patients at military medical facilities treating injured U.S. service members, 2002-2004 |journal=MMWR Morb. Mortal. Wkly. Rep. |volume=53 |issue=45 |pages=1063–6 |year=2004 |pmid=15549020 |doi= |url=http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5345a1.htm}}</ref>
===''Pseudomonas''===
''[[Pseudomonas aeruginosa]]'' is a highly relevant [[opportunistic pathogen]]. One of the most worrisome characteristics of ''[[P. aeruginosa]]'' consists in its low [[antibiotic]] susceptibility. This low susceptibility is attributable to a concerted action of [[multidrug efflux pump]]s with chromosomally-encoded [[antibiotic resistance]] genes and the low permeability of the bacterial cellular envelopes. Besides intrinsic resistance, ''P. aeruginosa'' easily develop acquired resistance either by [[mutation]] in chromosomally-encoded genes, or by the horizontal gene transfer of antibiotic resistance determinants. Development of [[multidrug resistance]] by ''P. aeruginosa'' isolates requires several different genetic events that include acquisition of different mutations and/or horizontal transfer of antibiotic resistance genes. Hypermutation favours the selection of mutation-driven antibiotic resistance in ''P. aeruginosa'' strains producing chronic infections, whereas the clustering of several different antibiotic resistance genes in [[integron]]s favours the concerted acquisition of antibiotic resistance determinants. Some recent studies have shown that phenotypic resistance associated to [[biofilm]] formation or to the emergence of small-colony-variants may be important in the response of ''P. aeruginosa'' populations to [[antibiotic]]s treatment.<ref name=Cornelis>{{cite book | author = Cornelis P (editor). | title = Pseudomonas: Genomics and Molecular Biology | edition = 1st ed. | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/pseudo | isbn=978-1-904455-19-6 ]}}</ref>
==Role of animals==
[[Methicillin Resistant Staphylococcus Aureus|MRSA]] is acknowledged to be a human [[commensal]] and [[pathogen]]. MRSA has been found in cats, dogs and horses, where it can cause the same problems as it does in humans. Owners can transfer the organism to their pets and vice-versa, and MRSA in animals is generally believed to be derived from humans.
Currently, it is estimated that greater than 70%{{fact|date=December 2007}} of the antibiotics used in the US are given to food animals (e.g. chickens, pigs and cattle) in the absence of disease. Antibiotic use in food animal production has been associated with the emergence of antibiotic-resistant strains of bacteria including [[Salmonella]], [[Campylobacter]], [[Escherichia coli]] and [[Enterococcus]], among others. There is substantial evidence from the US and European Union that these resistant bacteria cause antibiotic-resistant infections in humans. The [[American Society for Microbiology]] (ASM), the [[American Public Health Association]] (APHA) and the [[American Medical Association]] (AMA) have called for substantial restrictions on antibiotic use in food animal production including an end to all non-therapeutic uses. The food animal and pharmaceutical industries have fought hard to prevent new regulations that would limit the use of antibiotics in food animal production. For example, in 2000 the [[US Food and Drug Administration]] (FDA) announced their intention to rescind approval for [[fluoroquinolone]] use in poultry production because of substantial evidence linking it to the emergence of fluoroquinolone resistant Campylobacter infections in humans. The final decision to ban fluoroquinolones from use in poultry production was not made until 5 years later because of challenges from the food animal and pharmaceutical industries.<ref>{{cite journal | author=Nelson JM, Chiller TM, Powers JH, Angulo FJ | title=Fluoroquinolone-resistant ''Campylobacter'' species and the withdrawal of fluoroquinolones from use in poultry: A public health success story | journal=Clin Infect Dis | year=2007 | volume=44 | pages=977–80 | url=http://www.journals.uchicago.edu/CID/journal/issues/v44n7/41120/41120.html }}</ref> Today, there are two federal bills (S.742 and H.R. 2562) aimed at phasing out non-therapeutic antibiotics in US food animal production. These bills are endorsed by many public health and medical organizations including the [[American Nurses Association]] (ANA), the [[American Academy of Pediatrics]] (AAP), and the [[American Public Health Association]] (APHA).
==Alternatives==
===Prevention===
[[Hand washing|Washing hands]] properly reduces the chance of getting infected or spreading infection. Thoroughly washing or avoiding raw foods such as fruits, vegetables, raw eggs, and undercooked meat can also reduce the chance of an infection. High risk activities include: unprotected sex;<ref name="pmid11263546">{{cite journal |author= |title=Resurgent bacterial sexually transmitted disease among men who have sex with men--King County, Washington, 1997-1999 |journal=MMWR Morb. Mortal. Wkly. Rep. |volume=48 |issue=35 |pages=773–7 |year=1999 |pmid=11263546 |doi= |url=http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4835a1.htm}}</ref><ref name="pmid15550210">{{cite journal |author=Marrazzo JM |title=Barriers to infectious disease care among lesbians |journal=Emerging Infect. Dis. |volume=10 |issue=11 |pages=1974–8 |year=2004 |pmid=15550210 |doi= |url=http://www.cdc.gov/ncidod/eid/vol10no11/04-0467.htm}}</ref><ref name="pmid16888612">{{cite journal |author=Workowski KA, Berman SM |title=Sexually transmitted diseases treatment guidelines, 2006 |journal=MMWR Recomm Rep |volume=55 |issue=RR-11 |pages=1–94 |year=2006 |pmid=16888612 |doi= |url=http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5511a1.htm}}</ref> use of equipment in a public gymnasium or on a playground; being a patient in a nursing home or hospital; being a prison inmate; visiting a barbershop; the sharing of personal products (cosmetic items, lotion, bedding, toothpaste, headphones, nail clippers, shampoo).{{Fact|date=June 2007}}
Avoiding the use of [[antibiotics]], in some situations, can also reduce the chances of infection by antibiotic-resistant bacteria. In one study the use of fluoroquinolones are clearly associated with [[Clostridium difficile]] infection, which is a leading cause of [[nosocomial]] [[diarrhea]] in the United States,<ref name="pmid12781017">{{cite journal |author=McCusker ME, Harris AD, Perencevich E, Roghmann MC |title=Fluoroquinolone use and Clostridium difficile-associated diarrhea |journal=Emerging Infect. Dis. |volume=9 |issue=6 |pages=730–3 |year=2003 |pmid=12781017 |doi= |url-http://www.cdc.gov/ncidod/eid/vol9no6/02-0385.htm}}</ref> and a major cause of death, worldwide.<ref name="pmid9866738">{{cite journal |author=Frost F, Craun GF, Calderon RL |title=Increasing hospitalization and death possibly due to Clostridium difficile diarrheal disease |journal=Emerging Infect. Dis. |volume=4 |issue=4 |pages=619–25 |year=1998 |pmid=9866738 |doi= |url=http://www.cdc.gov/ncidod/eid/vol4no4/frost.htm }}</ref>
[[Vaccine]]s do not suffer the problem of resistance because a vaccine enhances the body's natural defenses, while an antibiotic operates separately from the body's normal defenses. Nevertheless, new strains may [[evolve]] that escape immunity induced by vaccines.
While theoretically promising, anti-staphylococcal vaccines have shown limited efficacy, because of immunological variation between ''Staphylococcus'' species, and the limited duration of effectiveness of the antibodies produced. Development and testing of more effective vaccines is under way.
===Phage therapy===
[[Phage therapy]], an approach that has been extensively researched and utilized as a therapeutic agent for over 60 years, especially in the [[Soviet Union]], is an alternative that might help with the problem of resistance. Phage Therapy was widely used in the United States until the discovery of antibiotics, in the early 1940's. Bacteriophages or "phages" are viruses that invade bacterial cells and, in the case of lytic phages, disrupt bacterial metabolism and cause the bacterium to [[lysis|lyse]]. Phage Therapy is the therapeutic use of lytic [[bacteriophages]] to treat [[pathogenic]] bacterial infections.<ref>{{cite journal
| title=Phages and their application against drug-resistant bacteria
| journal=J. Chem. Technol. Biotechnol.)
| year=2001
| volume=76
| pages=689–699
| author=N Chanishvili, T Chanishvili, M. Tediashvili, P.A. Barrow
| url=http://cat.inist.fr/?aModele=afficheN&cpsidt=1096871 }}</ref><ref>{{cite journal
| title=The use of a novel biodegradable preparation capable of the sustained release of bacteriophages and ciprofloxacin, in the complex treatment of multidrug-resistant Staphylococcus aureus-infected local radiation injuries caused by exposure to Sr90
| author=D. Jikia, N. Chkhaidze, E. Imedashvili, I. Mgaloblishvili, G. Tsitlanadze
| journal=Clinical & Experimental Dermatology
| year=2005
| volume=30
| pages=23
| url=http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2230.2004.01600.x?journalCode=ced }}</ref><ref>{{cite journal
| title=Bacteriophages as an efficient therapy for antibiotic-resistant septicemia in man.
| author=Weber-Dabrowska B, Mulczyk M, Gorski A.
| journal=Transplant Proc.
| year=2003
| url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12826166 }}</ref>
Bacteriophage therapy is an important alternative to antibiotics in the current era of multidrug resistant pathogens. A review of studies that dealt with the therapeutic use of phages from 1966–1996 and few latest ongoing phage therapy projects via internet showed: phages were used topically, orally or systemically in Polish and Soviet studies. The success rate found in these studies was 80–95% with few gastrointeslinal or allergic side effects. British studies also demonstrated significant efficacy of phages against ''[[Escherichia coli]]'', ''[[Acinetobacter]]'' spp., ''[[Pseudomonas]]'' spp and ''[[Staphylococcus aureus]]''. US studies dealt with improving the bioavailability of phage. Phage therapy may prove as an important alternative to antibiotics for treating multidrug resistant pathogens.<ref>{{cite journal | title= Bacteriophage therapy: an alternative to conventional antibiotics. | author=Mathur MD, Vidhani S, Mehndiratta PL.| journal=J Assoc Physicians India | year=2003 | volume=51 | pages=593–6 | url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15266928&query_hl=13&itool=pubmed_docsum | PMID 15266928 }}</ref> <ref name=McGrath>{{cite book | author = Mc Grath S and van Sinderen D (editors). | title = Bacteriophage: Genetics and Molecular Biology | edition = 1st ed. | publisher = Caister Academic Press | year = 2007 | url=http://www.horizonpress.com/phage | id = [http://www.horizonpress.com/phage ISBN 978-1-904455-14-1 ]}}</ref>
==Development of new drugs==
Until recently, [[research and development]] (R&D) efforts have provided new drugs in time to treat bacteria that became resistant to older antibiotics. That is no longer the case. The potential crisis at hand is the result of a marked decrease in industry R&D, government inaction, and the increasing prevalence of resistant bacteria. Infectious disease physicians are alarmed by the prospect that effective antibiotics may not be available to treat seriously ill patients in the near future.
The pipeline of new antibiotics is drying up. Major [[list of pharmaceutical companies|pharmaceutical companies]] are losing interest in the antibiotics market because these drugs may not be as profitable as drugs that treat chronic (long-term) conditions and lifestyle issues.<ref>{{cite web |title=Bad Bugs, No Drugs Executive Summary |url=http://www.idsociety.org/PrintFriendly.aspx?id=5558 |date= |publisher=Infectious Diseases Society of America |accessdate=2007-12-11}}</ref>
The resistance problem demands that a renewed effort be made to seek antibacterial agents effective against pathogenic bacteria resistant to current antibiotics. One of the possible strategies towards this objective is the rational localization of [[bioactive]] [[phytochemical]]s. Plants have an almost limitless ability to synthesize [[aromatic]] substances, most of which are [[phenol]]s or their oxygen-substituted derivatives such as [[tannin]]s. Most are secondary [[metabolite]]s, of which at least 12,000 have been isolated, a number estimated to be less than 10% of the total{{Fact|date=February 2007}}. In many cases, these substances serve as plant defense mechanisms against [[predation]] by [[microorganism]]s, [[insect]]s, and [[herbivore]]s. Many of the herbs and spices used by humans to season food yield useful medicinal compounds including those having antibacterial activity.<ref name="pmid15831135">{{cite journal |author=Wallace RJ |title=Antimicrobial properties of plant secondary metabolites |journal=Proc Nutr Soc |volume=63 |issue=4 |pages=621–9 |year=2004 |pmid=15831135 |doi=}}</ref><ref name="pmid12872531">{{cite journal |author=Thuille N, Fille M, Nagl M |title=Bactericidal activity of herbal extracts |journal=Int J Hyg Environ Health |volume=206 |issue=3 |pages=217–21 |year=2003 |pmid=12872531 |doi=}}</ref><ref name="pmid12410554">{{cite journal |author=Singh G, Kapoor IP, Pandey SK, Singh UK, Singh RK |title=Studies on essential oils: part 10; antibacterial activity of volatile oils of some spices |journal=Phytother Res |volume=16 |issue=7 |pages=680–2 |year=2002 |pmid=12410554 |doi=10.1002/ptr.951}}</ref>
Traditional healers have long used plants to prevent or cure infectious conditions. Many of these plants have been investigated scientifically for antimicrobial activity and a large number of plant products have been shown to inhibit growth of pathogenic bacteria. A number of these agents appear to have structures and modes of action that are distinct from those of the antibiotics in current use, suggesting that [[cross-resistance]] with agents already in use may be minimal. For example the combination of [[5'-methoxyhydnocarpine]] and [[berberine]] in herbs like [[Hydrastis canadensis]] and [[Berberis vulgaris]] can block the MDR-pumps that cause multidrug resistance. This has been shown for [[Staphylococcus aureus]].<ref name="pmid10677479">{{cite journal |author=Stermitz FR, Lorenz P, Tawara JN, Zenewicz LA, Lewis K |title=Synergy in a medicinal plant: antimicrobial action of berberine potentiated by 5'-methoxyhydnocarpin, a multidrug pump inhibitor |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=97 |issue=4 |pages=1433–7 |year=2000 |pmid=10677479 |doi=10.1073/pnas.030540597 |url=http://www.pnas.org/cgi/content/full/97/4/1433}}</ref>
==Applications==
Antibiotic resistance is an important tool for [[genetic engineering]]. By constructing a [[plasmid]] which contains an antibiotic resistance gene as well as the gene being engineered or expressed, a researcher can ensure that when bacteria replicate, only the copies which carry along the plasmid survive. This ensures that the gene being manipulated passes along when the bacteria replicates.
The most commonly used antibiotics in genetic engineering are generally "older" antibiotics which have largely fallen out of use in clinical practice. These include:
* [[ampicillin]]
* [[kanamycin]]
* [[tetracycline]]
* [[chloramphenicol]]
Industrially the use of antibiotic resistance is disfavored since maintaining bacterial cultures would require feeding them large quantities of antibiotics. Instead, the use of [[auxotrophic]] bacterial strains (and function-replacement plasmids) is preferred.
==See also==
*[[Repressor lexA|LexA]]
*[[Efflux]]
*[[List of environment topics]]
*[[Nosocomial infection]]
*[[Tuberculosis]]
*[[Bacterial conjugation]]
*[[Drug of last resort]]
==References==
* {{cite journal |author=Soulsby EJ |title=Resistance to antimicrobials in humans and animals |journal=BMJ |volume=331 |issue=7527 |pages=1219–20 |year=2005 |pmid=16308360 |doi=10.1136/bmj.331.7527.1219 |url=http://www.bmj.com/cgi/content/full/331/7527/1219}}
==Footnotes==
{{reflist|2}}
==External links==
* [http://www.mrsaactionuk.net MRSA Action UK Registered Charity No. 1115672 - Supporting sufferers, dependants and carers in the UK]
* [http://www.cdc.gov/ncidod/dhqp/ar_mrsa_spotlight_2006.html CDC Article on Hospital Acquired MRSA]
* [http://www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html CDC Article on Community Acquired MRSA]
* [http://www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf CDC Guideline "Management of Multidrug-Resistant Organisms in Healthcare Settings, 2006"]
* [http://www.cc.nih.gov/hes/vre.html Vancomycin Resistant Enterococcus—Guidelines for Healthcare Workers]
* [http://antibiotic.org Alliance for the Prudent Use of Antibiotics]
*[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16492187&query_hl=1&itool=pubmed_docsum Quantifying potential human health impacts of animal antibiotic use: Enrofloxacin and macrolides in chickens.]
* [http://www.fda.gov/fdac/features/795_antibio.html|The Rise of Antibiotic-Resistant Infections]
* [http://www.bacteriophagetherapy.info Information about phage therapy – a possible alternative to antibiotics in case of resistant infections]
* [http://www.gmo-safety.eu/en/gene_transfer/44.docu.html Antibiotic-resistance genes as markers] Once necessary, now undesirable
*[http://cbs5.com/health/local_story_025195614.html CBS Article on Phage Therapy and Antibiotic Resistance]
* [http://www.eu-burden.info/burden/pages/home.php BURDEN of Resistance and Disease in European Nations - An EU-Project to estimate the financial burden of antibiotic resistance in European Hospitals ]
[[Category:Antibiotics]]
[[ar:مقاومة المضادات الحيوية]]
[[da:Antibiotikaresistens]]
[[de:Antibiotikum-Resistenz]]
[[fr:Résistance aux antibiotiques]]
[[it:Resistenza agli antibiotici]]
[[nl:Resistentie tegen antibiotica]]
[[pl:Oporność na antybiotyki]]
[[pt:Resistência antibiótica]]
[[ro:Rezistenţa la antibiotice]]
[[sv:Antibiotikaresistens]]
[[uk:Антибіотичний опір]]