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Abstract
The main factors affecting the evolution of drug resistance in malaria according to theoretical models are reviewed here. The overwhelming influence on the emergence and rate of spread of drug resistance is the proportion of infected hosts that are treated with drugs. A second important effect is drug efficacy in killing parasites. Factors such as average transmission rate, recombination, the biological cost of resistance, and the mode of gene action also influence the rate of spread but have relatively minor impacts. A simple population dynamics model that captures the epidemiological effects of drug treatment and resistance, as opposed to a population genetics model that does not, is presented in order to illustrate the main conclusions.
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Affiliation(s)
- M J Mackinnon
- School of Biological Sciences, University of Edinburgh, West Mains Rd., Edinburgh EH9 3JT, UK.
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102
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103
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104
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Boni MF, Feldman MW. EVOLUTION OF ANTIBIOTIC RESISTANCE BY HUMAN AND BACTERIAL NICHE CONSTRUCTION. Evolution 2005. [DOI: 10.1554/04-425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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105
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Bruinsma N, Kristinsson KG, Bronzwaer S, Schrijnemakers P, Degener J, Tiemersma E, Hryniewicz W, Monen J, Grundmann H. Trends of penicillin and erythromycin resistance among invasive Streptococcus pneumoniae in Europe. J Antimicrob Chemother 2004; 54:1045-50. [PMID: 15531598 DOI: 10.1093/jac/dkh458] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To forecast trends in resistance to penicillin and erythromycin among Streptococcus pneumoniae in Europe. METHODS Since 1999, the European Antimicrobial Resistance Surveillance System (EARSS) has collected routine antimicrobial susceptibility test results of S. pneumoniae. To observe and predict changes of reduced susceptibility over time, we used a multinomial logistic regression model. RESULTS Large variations in penicillin and erythromycin non-susceptibility were observed between countries, and reduced susceptibility to erythromycin (17%) has become more frequent than reduced susceptibility to penicillin (10%) in Europe overall. An overall decrease in single penicillin non-susceptibility, but an increase in dual non-susceptibility was observed, indicating a shift of single penicillin to combined non-susceptibility with erythromycin. By 2006, the proportion of single erythromycin and dual non-susceptibility could increase to as much as 20.4% and 8.9%, respectively. CONCLUSIONS Our results indicate that appropriately dosed beta-lactams for empirical therapy are still the treatment of choice, and that macrolides should be used with prudence.
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Affiliation(s)
- Nienke Bruinsma
- Centre for Infectious Disease Epidemiology, National Institute for Public Health and the Environment, PO Box 1, 3720 BA Bilthoven, The Netherlands.
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106
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Kaplancikli ZA, Turan-Zitouni G, Revial G, Guven K. Synthesis and study of antibacterial and antifungal activities of Novel 2-[[(benzoxazole/benzimidazole-2-yl)sulfanyl] acetylamino]thiazoles. Arch Pharm Res 2004; 27:1081-5. [PMID: 15595406 DOI: 10.1007/bf02975108] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Several 2-[[(benzoxazole/benzimidazole-2-yl)sulfanyl]acetylamino]thiazoles derivatives were synthesized by reacting 4-substituted-2-(chloroacetylamino)thiazoles with benzoxazole/benzimidazole-2-thioles in acetone and in the presence of K2CO3. The chemical structures of the compounds were elucidated by IR, 1H-NMR, and FAB(+)-MS spectral data. Their antimicrobial activities against Micrococcus luteus (NRLL B-4375), Bacillus cereus (NRRL B-3711), Proteus vulgaris (NRRL B-123), Salmonella typhimurium (NRRL B-4420), Staphylococcus aureus (NRRL B-767), Escherichia coli (NRRL B-3704), Candida albicans and Candida globrata (isolates obtained from Osmangazi Uni. Fac.of Medicine) were investigated and in this investigation, a significant level of activity was illustrated.
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Affiliation(s)
- Zafer Asim Kaplancikli
- Anadolu University, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, 26470 Eskisehir, Turkey.
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107
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Diep BA, Sensabaugh GF, Somboonna N, Somboona NS, Carleton HA, Perdreau-Remington F. Widespread skin and soft-tissue infections due to two methicillin-resistant Staphylococcus aureus strains harboring the genes for Panton-Valentine leucocidin. J Clin Microbiol 2004; 42:2080-4. [PMID: 15131173 PMCID: PMC404676 DOI: 10.1128/jcm.42.5.2080-2084.2004] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Infections caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are emerging as a major public health problem. CA-MRSA has been associated previously with skin and soft-tissue infection (SSTI) and with carriage of staphylococcal cassette chromosome mec (SCCmec) type IV and the Panton-Valentine leucocidin (PVL) virulence factor. To assess the clonal distribution of PVL-carrying strains and the association with SSTI in the San Francisco Bay area, we surveyed six collections of S. aureus isolates-671 isolates in all-collected between 1997 and 2002 originating from inpatient and outpatient clinical specimens and from a community-based sampling. Isolates were genotyped by pulsed-field gel electrophoresis, multilocus restriction fragment typing, and multilocus sequence typing and assayed for the PVL virulence factor. The S. aureus populations showed a high proportion of PVL-carrying strains, with frequencies ranging up to 70% in MRSA isolated from jail inmate patients and 69% in MRSA from patients receiving surgical treatment at an outpatient clinic specializing in treating SSTIs. PVL-carrying isolates were identified in nine clonal groups, but 88.5% of the PVL-carrying MRSA isolates belonged to only two clonal groups. These two clonal groups carried the SCCmec type IV resistance determinant and were more likely than other clonal groups to be recovered from SSTI sites than from other sites (P < 0.0001). There is evidence of clonal replacement over the period from 1999 to 2002, with one of these two clonal groups being supplanted by the other.
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Affiliation(s)
- Binh An Diep
- Division of Infectious Diseases, School of Public Health, University of California, Berkeley, California 94720, USA
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108
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Warren WJ, Jeter RM, Kimbrough RC, Zak JC. Population patterns and antimicrobial resistance ofAeromonasin urban playa lakes. Can J Microbiol 2004; 50:397-404. [PMID: 15284885 DOI: 10.1139/w04-029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Bacteria belonging to the genus Aeromonas are indigenous to aquatic environments. Once regarded as unimportant human pathogens, reports of opportunistic infections caused by these organisms have appeared increasingly in the medical literature. To estimate the potential for human infection by Aeromonas where limited water resources are being used intensively, we studied the spatial and temporal variation and incidence of antimicrobial resistance among environmental isolates of Aeromonas from two urban playa lakes in Lubbock, Texas. Aeromonas population densities varied seasonally, with the highest densities occurring from mid-April to late October. The greatest range of densities was 100-fold, from 2.50 to 255.17 colony-forming units per 0.1 mL of water sample. Densities also varied with water depth, although the variation did not display a consistent pattern. One hundred fifty-one Aeromonas isolates were divided into 10 species or subspecies groups by using the BIOLOG identification system. Nine isolates displayed resistance to co-trimoxazole, tetracycline, and cefuroxime, and none was resistant to more than one of these antimicrobial agents. In summary, the results of this study showed that the densities of Aeromonas peak in the late spring and again in late summer, times when human activity around the playa lakes is also high. Thus, we infer that human exposure to these potential pathogens varies seasonally. Compared to other published studies, the incidence of antimicrobial-resistant Aeromonas is relatively low in urban playa lakes in Lubbock, Texas. Nevertheless, resistant organisms were detected.Key words: Aeromonas, water, playa, antibiotic resistance, population dynamics.
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Affiliation(s)
- William J Warren
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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109
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Langford FM, Weary DM, Fisher L. Antibiotic resistance in gut bacteria from dairy calves: a dose response to the level of antibiotics fed in milk. J Dairy Sci 2004; 86:3963-6. [PMID: 14740833 DOI: 10.3168/jds.s0022-0302(03)74006-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dairy calves are commonly fed milk from cows treated with antibiotics. The concentration of beta-lactam antibiotic residues found in milk from treated cows was used to determine the range of concentrations of penicillin used in a dose-regulated experiment. Thirty-one Holstein calves were randomly assigned to milk with penicillin G added at concentrations of 0, 6.25, 12.5, 25, and 50 microl/kg. Fecal swabs were taken from each calf twice weekly. Resistance to penicillin was tested by measuring the zone of inhibition in bacterial growth around a disk impregnated with the antibiotic. Inhibition was greatest for bacteria from calves fed milk with no penicillin (2.89 +/- 0.14 mm), and declined as the penicillin dose provided in the milk increased (to a low of 0.70 +/- 0.10 for the 50 microl/kg treatment group). In conclusion, resistance of gut bacteria to antibiotics increases with increasing concentrations of penicillin in the milk fed to dairy calves.
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Affiliation(s)
- F M Langford
- Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Veterinary Centre, Easter Bush, Midlothian, EH25 9RG, UK
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110
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Iwasa Y, Michor F, Nowak MA. Evolutionary dynamics of escape from biomedical intervention. Proc Biol Sci 2004; 270:2573-8. [PMID: 14728779 PMCID: PMC1691545 DOI: 10.1098/rspb.2003.2539] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Viruses, bacteria, eukaryotic parasites, cancer cells, agricultural pests and other inconvenient animates have an unfortunate tendency to escape from selection pressures that are meant to control them. Chemotherapy, anti-viral drugs or antibiotics fail because their targets do not hold still, but evolve resistance. A major problem in developing vaccines is that microbes evolve and escape from immune responses. The fundamental question is the following: if a genetically diverse population of replicating organisms is challenged with a selection pressure that has the potential to eradicate it, what is the probability that this population will produce escape mutants? Here, we use multi-type branching processes to describe the accumulation of mutants in independent lineages. We calculate escape dynamics for arbitrary mutation networks and fitness landscapes. Our theory shows how to estimate the probability of success or failure of biomedical intervention, such as drug treatment and vaccination, against rapidly evolving organisms.
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Affiliation(s)
- Yoh Iwasa
- Department of Biology, Kyushu University, Fukuoka 812-8581, Japan
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111
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Blake DP, Hillman K, Fenlon DR, Low JC. Transfer of antibiotic resistance between commensal and pathogenic members of the Enterobacteriaceae under ileal conditions. J Appl Microbiol 2003; 95:428-36. [PMID: 12911689 DOI: 10.1046/j.1365-2672.2003.01988.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM To determine the rate of antibiotic resistance transmission between commensal and pathogenic representatives of the Enterobacteriaceae. METHODS AND RESULTS Through the use of a validated in vitro simulation of the porcine ileum, the transmission of antibiotic resistance was detected between commensal Escherichia coli, E. coli O157 and Salmonella spp. Countable transconjugant populations arose readily and, in one example, proved capable of indefinite persistence. CONCLUSIONS Genetic material conferring antibiotic resistance is readily transmissible between members of the Enterobacteriaceae under ileal conditions. Recipient phenotype influences the persistence of multi-resistant transconjugants. SIGNIFICANCE AND IMPACT OF THE STUDY The observation that the conjugal transmission of antibiotic resistance is commonplace under ileal conditions impacts primarily on the risk of food contamination by multi-resistant bacteria. The establishment of a multi-resistant transconjugant population as a dominant member of the microflora maintains a genetic reservoir of antimicrobial resistance.
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Affiliation(s)
- D P Blake
- Centre for Microbiological Research, Veterinary Science Division, SAC, Craibstone, Aberdeen, AB21 9YA, UK.
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112
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He Y, Wu B, Yang J, Robinson D, Risen L, Ranken R, Blyn L, Sheng S, Swayze EE. 2-piperidin-4-yl-benzimidazoles with broad spectrum antibacterial activities. Bioorg Med Chem Lett 2003; 13:3253-6. [PMID: 12951103 DOI: 10.1016/s0960-894x(03)00661-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A series of 2-piperidin-4-yl-benzimidazoles were synthesized and evaluated for antibacterial activities. Certain compounds inhibit bacterial growth with low micromolar minimal inhibitory concentration (MIC). These benzimidazoles are effective against both Gram-positive and Gram-negative bacteria of clinical importance, particularly enterococci, and represent a new class of potential antibacterial agents.
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Affiliation(s)
- Yun He
- Ibis Therapeutics, A Division of Isis Pharmaceuticals, Inc., 2292 Faraday Avenue, Carlsbad, CA 92008, USA.
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113
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Abstract
To address the worsening problem of antibiotic-resistant bacteria there is an urgent need to develop new antibiotics. Comparative genomics and molecular genetics are being applied to produce lists of essential new targets for compound screening programmes. Combinatorial chemistry and structural biology are being applied to rapidly explore and optimize the interactions between lead compounds and their biological targets. Several compounds that have been identified from target-based screens are now in development, but technical and economic constraints might result in a trickle, rather than a flood, of new antibiotics onto the market in the near future.
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Affiliation(s)
- Diarmaid Hughes
- Department of Cell and Molecular Biology, Box 596, The Biomedical Center, Uppsala University, S-751 24 Uppsala, Sweden.
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114
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McCormick AW, Whitney CG, Farley MM, Lynfield R, Harrison LH, Bennett NM, Schaffner W, Reingold A, Hadler J, Cieslak P, Samore MH, Lipsitch M. Geographic diversity and temporal trends of antimicrobial resistance in Streptococcus pneumoniae in the United States. Nat Med 2003; 9:424-30. [PMID: 12627227 DOI: 10.1038/nm839] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2002] [Accepted: 01/24/2003] [Indexed: 11/09/2022]
Abstract
Resistance of Streptococcus pneumoniae to antibiotics is increasing throughout the United States, with substantial variation among geographic regions. We show that patterns of geographic variation are best explained by the intensity of selection for resistance, which is reflected by differences between the proportions of resistance within individual serotypes, rather than by differences between the frequencies of particular serotypes. Using a mathematical transmission model, we analyzed temporal trends in the proportions of singly and dually resistant organisms and found that pneumococcal strains resistant to both penicillin and erythromycin are increasing faster than strains singly resistant to either. Using the model, we predict that by 1 July 2004, in the absence of a vaccine, 41% of pneumococci at the Centers for Disease Control and Prevention (CDC)'s Active Bacterial Core surveillance (ABCs) sites, taken together, will be dually resistant, with 5% resistant to penicillin only and 5% to erythromycin only.
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Affiliation(s)
- Althea W McCormick
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
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115
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McDermott PF, Walker RD, White DG. Antimicrobials: modes of action and mechanisms of resistance. Int J Toxicol 2003; 22:135-43. [PMID: 12745995 DOI: 10.1080/10915810305089] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
After six decades of widespread antibiotic use, bacterial pathogens of human and animal origin are becoming increasingly resistant to many antimicrobial agents. Antimicrobial resistance develops through a limited number of mechanisms: (a). permeability changes in the bacterial cell wall/membrane, which restrict antimicrobial access to target sites; (b). active efflux of the antimicrobial from the cell; (c). mutation in the target site; (d). enzymatic modification or degradation of the antimicrobial; and (e). acquisition of alternative metabolic pathways to those inhibited by the drug. Numerous bacterial antimicrobial resistance phenotypes result from the acquisition of external genes that may provide resistance to an entire class of antimicrobials. These genes are frequently associated with large transferable extrachromosomal DNA elements called plasmids, on which may be other mobile DNA elements such as transposons and integrons. An array of different resistance genes may accumulate on a single mobile element, presenting a situation in which multiple antibiotic resistance can be acquired via a single genetic event. The versatility of bacterial populations in adapting to toxic environments, along with their facility in exchanging DNA, signifies that antibiotic resistance is an inevitable biological phenomenon that will likely continue to be a chronic medical problem. Successful management of current antimicrobials, and the continued development of new ones, is vital to protecting human and animal health against bacterial pathogens.
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Affiliation(s)
- Patrick F McDermott
- Office of Research, Center for Veterinary Medicine, US Food and Drug Administration, Laurel, Maryland 20708, USA.
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116
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Wichelhaus TA, Böddinghaus B, Besier S, Schäfer V, Brade V, Ludwig A. Biological cost of rifampin resistance from the perspective of Staphylococcus aureus. Antimicrob Agents Chemother 2002; 46:3381-5. [PMID: 12384339 PMCID: PMC128759 DOI: 10.1128/aac.46.11.3381-3385.2002] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Resistance determinants that interfere with normal physiological processes in the bacterial cell usually cause a reduction in biological fitness. Fitness assays revealed that 17 of 18 in vitro-selected chromosomal mutations within the rpoB gene accounting for rifampin resistance in Staphylococcus aureus were associated with a reduction in the level of fitness. There was no obvious correlation between the level of resistance to rifampin and the level of fitness loss caused by rpoB mutations. Among 23 clinical rifampin-resistant S. aureus isolates from six countries, only seven different rpoB genotypes could be identified, whereby the mutation 481His-->Asn was present in 21 (91%) of these 23 isolates. The mutation 481His-->Asn, in turn, which confers low-level rifampin resistance on its own, was not shown to be associated with a cost of resistance in vitro. The restriction to distinct mutations that confer rifampin resistance in vivo, as demonstrated here, appears to be determined by the Darwinian fitness of the organisms.
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Affiliation(s)
- Thomas A Wichelhaus
- Institut für Medizinische Mikrobiologie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
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117
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Pym AS, Saint-Joanis B, Cole ST. Effect of katG mutations on the virulence of Mycobacterium tuberculosis and the implication for transmission in humans. Infect Immun 2002; 70:4955-60. [PMID: 12183541 PMCID: PMC128294 DOI: 10.1128/iai.70.9.4955-4960.2002] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The usefulness of isoniazid (INH), a key component of short-course chemotherapy of tuberculosis, is threatened by the emergence of drug-resistant strains of Mycobacterium tuberculosis with mutations in the katG gene. It is shown here that the most commonly occurring KatG mutation, where Ser 315 is replaced by Thr (S315T), is associated with clinically significant levels of INH resistance. In contrast to another resistant isolate, in which Pro replaces Thr 275, the S315T mutant produces active catalase-peroxidase and is virulent in the mouse model of the disease, indicating that a significant loss of bacterial fitness does not result from this frequent mutation. The implications of this finding for the transmission and reactivation of multidrug-resistant strains of M. tuberculosis are severe.
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Affiliation(s)
- Alexander S Pym
- Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, Paris, France
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118
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Abstract
PURPOSE OF THE REVIEW Nosocomial infections remain among the most common treatment complications, particularly in intensive care unit patients. In many countries antibiotic resistance is increasingly hampering treatment of these infections. Preventive strategies have therefore become more important and have been directed both against the development of specific infections and against the spread of antibiotic-resistant pathogens. The present review addresses recent data on the latter issue. In particular, we discuss the first approaches to use mathematical modelling as a tool to analyse and guide strategies to prevent infection, and the effects of antibiotic cycling. RECENT FINDINGS Several mathematical models to address the dynamics of pathogen transmission in hospital settings have been developed. One of the models may allow quantification of the effects of different strategies to prevent infection in intensive care units, and another may be used to determine the relative importance of different colonization routes, without the need for expensive genotyping methods. The results of the first prospective studies on antibiotic cycling are inconclusive, and again mathematical modelling may help to provide testable hypotheses for such interventions. Finally, recent studies have shown that alcohol-based hand rubs are better than hand washing with soap and water for most hand disinfection purposes. SUMMARY The first results of use of mathematical modelling to guide infection control strategies should be subjected to prospective, empirical testing in order to determine their clinical usefulness. More rigorously designed studies are needed to determine the benefits of antibiotic cycling strategies. Hands should be disinfected with alcohol-based hand rubs, which should be available at each bedside.
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Affiliation(s)
- Marc J M Bonten
- Department of Internal Medicine, Division of Acute Internal Medicine & Infectious Diseases, University Medical Center Utrecht, Utrecht, The Netherlands.
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119
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Abstract
The emergence of bacterial strains exhibiting resistance to multiple antibiotic classes poses a major threat to medicine and public health. This has been compounded over the last few decades by the failure of drug discovery programmes to provide new broad spectrum antibacterials with novel modes of action. As a consequence, there is renewed interest in antibacterial targets which disrupt the capacity of pathogenic bacteria to cause infection by attenuating virulence. In this respect, one crucial feature of almost all bacterial infections is that the pathogen must attain a critical cell population density sufficient to overwhelm the host defences. Many pathogens are now known to regulate diverse physiological processes, including virulence, in a cell density dependent manner through cell-cell communication. This phenomenon, which relies upon the interaction of a diffusible signal molecule with a sensor kinase or response regulator, has become known as 'quorum sensing'. This review considers the molecular basis of quorum sensing and whether it constitutes a potential therapeutic target for the design of small molecule antagonists capable of controlling infection by attenuating adaptation to the host environment.
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Affiliation(s)
- Paul Williams
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH UK.
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120
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Lipsitch M, Singer RS, Levin BR. Antibiotics in agriculture: when is it time to close the barn door? Proc Natl Acad Sci U S A 2002; 99:5752-4. [PMID: 11983874 PMCID: PMC122845 DOI: 10.1073/pnas.092142499] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Marc Lipsitch
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
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121
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Abstract
The need to stem the growing problem of antimicrobial resistance has prompted multiple, sometimes conflicting, calls for changes in the use of antimicrobial agents. One source of disagreement concerns the major mechanisms by which antibiotics select resistant strains. For infections like tuberculosis, in which resistance can emerge in treated hosts through mutation, prevention of antimicrobial resistance in individual hosts is a primary method of preventing the spread of resistant organisms in the community. By contrast, for many other important resistant pathogens, such as penicillin-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus faecium resistance is mediated by the acquisition of genes or gene fragments by horizontal transfer; resistance in the treated host is a relatively rare event. For these organisms, indirect, population-level mechanisms of selection account for the increase in the prevalence of resistance. These mechanisms can operate even when treatment has a modest, or even negative, effect on an individual host's colonization with resistant organisms.
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Affiliation(s)
- Marc Lipsitch
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachussetts 02115, USA.
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122
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Jank B, Rath J. Antibiotic-resistance management on the farm. Trends Microbiol 2002; 10:11-2. [PMID: 11755078 DOI: 10.1016/s0966-842x(01)02273-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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