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Antibiotic Resistance (antibiotic + resistance)
Terms modified by Antibiotic Resistance Selected AbstractsEVOLUTION O ANTIBIOTIC RESISTANCE BY HUMAN AND BACTERIAL NECHE CONSTRUCTIONEVOLUTION, Issue 3 2005Maciej F. Boni Abstract Antibiotic treatment by humans generates strong viability selection for antibiotic-resistant bacterial strains. The frequency of host antibiotic use often determines the strength of this selection, and changing patterns of antibiotic use can generate many types of behaviors in the population dynamics of resistant and sensitive bacterial populations. In this paper, we present a simple model of hosts dimorphic for their tendency to use/avoid antibiotics and bacterial pathogens dimorphic in their resistance/sensitivity to antibiotic treatment. When a constant fraction of hosts uses antibiotics, the two bacterial strain populations can coexist unless host use-frequency is above a critical value; this critical value is derived as the ratio of the fitness cost of resistance to the fitness cost of undergoing treatment. When strain frequencies can affect host behavior, the dynamics may be analyzed in the light of niche construction. We consider three models underlying changing host behavior: conformism, the avoidance of long infections, and adherence to the advice of public health officials. In the latter two, we find that the pathogen can have quite a strong effect on host behavior. In particular, if antibiotic use is discouraged when resistance levels are high, we observe a classic niche-construction phenomenon of maintaining strain polymorphism even in parameter regions where it would not be expected. [source] CLINICAL NEED FOR OTOTOPICAL FLUOROQUINOLONES OUTWEIGHS MINISCULE RISK OF ANTIBIOTIC RESISTANCEJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 4 2006Sophie Couzos Dr No abstract is available for this article. [source] Antibiotic Resistance by Enzyme Inactivation: From Mechanisms to SolutionsCHEMBIOCHEM, Issue 10 2010Gianfranco De Pascale Resistance is fertile: Bacteria evade antibiotics by using a number of methods, but the selection and optimization of enzymes that destroy or modify drugs is a particularly prominent mechanism. We review recent advances in our understanding of the molecular mechanisms of these enzymes as well as efforts to block their activities through small molecule inhibitors. [source] Antibiotic Resistance in Bacteria: Novel Metalloenzyme InhibitorsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 4 2009Sung-Kun Kim ,-Lactam antibiotics are among the most important drugs used to fight bacterial infection. Overuse and misuse of ,-lactam antibiotics has caused the evolution of resistance mechanisms, allowing pathogenic bacteria to survive antibiotic treatment. The major source of resistance to ,-lactam antibiotics occurs through production of enzymes called ,-lactamases capable of catalyzing hydrolysis of the ,-lactam rings in these drug compounds. The metallo-,-lactamases have become a major threat due to their broad substrate specificities; there are no clinically useful inhibitors for these metalloenzymes. We have obtained single-stranded DNA's that are potent inhibitors of the Bacillus cereus 5/B/6 metallo-,-lactamase. These are rapid, reversible, non-competitive inhibitors of the metalloenzyme, with Ki and Ki, values in the nanomolar range. The inhibition patterns and metal ion dependence of their inhibition suggest that the oligonucleotides alter the coordination of the active site metal ion(s); inhibition is efficient and highly specific. Microbiological growth experiments, using combinations of ssDNA with the ,-lactam antibiotic cephalexin, reveal that the inhibitor is capable of causing cell death in liquid cultures of both Gram-positive and Gram-negative metallo-,-lactamase producing bacteria in the micromolar concentration range. [source] Acute effects of the antibiotic oxytetracycline on the bacterial community of the grass shrimp, Palaemonetes pugio,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Miguel Uyaguari Abstract The toxicity of oxytetracycline (OTC) was evaluated in adult grass shrimp, Palaemonetes pugio. Initially, static acute (96 h) toxicity tests were conducted with shrimp exposed from 0 to 1,000 mg/L OTC. A calculated lethal concentration 50% value of 683.30 mg/L OTC (95% confidence interval 610.85,764.40 mg/L) was determined from these tests, along with a lowest-observable-effect concentration of 750 mg/L and no-observable-effect concentration of 500 mg/L. Moreover, chronic sublethal effects of OTC exposure on grass shrimp intestinal bacterial population were assessed using doses from 0 to 32 mg/L OTC. The total viable counts in digestive tract content had levels between 5.2 and 1 × 104 colony-forming units per gram of tissue at times 0 and 96 h, respectively. Aeromonas hydrophila were the most resistant isolates (27.78%) to OTC exposure. Vibrio alginolyticus showed significant positive growth following exposure to OTC, whereas other bacterial species abundance declined over time. A total of 268 bacterial isolates were screened using antibiotic resistance analysis from a library containing 459 isolates. Among the tested isolates from the OTC treatments, 15.4% were resistant to OTC and 84.6% were OTC sensitive. Oxytetracycline was generally not consistently quantifiable with liquid chromatography-mass spectroscopy technique in shrimp homogenates. The only peak detected was at the 32 mg/L dose of OTC at 96 h. Nevertheless, OTC had a significant biological effect on the bacterial population. Antibiotic resistance to five other antibiotics (penicillin G, sulfathiazole, trimethoprim, trimethoprim and sulfamethoxazole, and tetracycline) was strongly associated with OTC exposures. The present study indicates that OTC toxicity effects in P. pugio and changes in the shrimp microbial community would only be expected under special circumstances. [source] Antibiotic resistance in staphylococci associated with cats and dogsJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2005S. Malik [source] Evolution and spread of antibiotic resistanceJOURNAL OF INTERNAL MEDICINE, Issue 2 2002B. Henriques Normark Abstract., Antibiotic resistance is a clinical and socioeconomical problem that is here to stay. Resistance can be natural or acquired. Some bacterial species, such as Pseudomonas aeruginosa, show a high intrinsic resistance to a number of antibiotics whereas others are normally highly antibiotic susceptible such as group A streptococci. Acquired resistance evolve via genetic alterations in the microbes own genome or by horizontal transfer of resistance genes located on various types of mobile DNA elements. Mutation frequencies to resistance can vary dramatically depending on the mechanism of resistance and whether or not the organism exhibits a mutator phenotype. Resistance usually has a biological cost for the microorganism, but compensatory mutations accumulate rapidly that abolish this fitness cost, explaining why many types of resistances may never disappear in a bacterial population. Resistance frequently occurs stepwise making it important to identify organisms with low level resistance that otherwise may constitute the genetic platform for development of higher resistance levels. Self-replicating plasmids, prophages, transposons, integrons and resistance islands all represent DNA elements that frequently carry resistance genes into sensitive organisms. These elements add DNA to the microbe and utilize site-specific recombinases/integrases for their integration into the genome. However, resistance may also be created by homologous recombination events creating mosaic genes where each piece of the gene may come from a different microbe. The selection with antibiotics have informed us much about the various genetic mechanisms that are responsible for microbial evolution. [source] Antibiotic resistance in Listeria species isolated from catfish fillets and processing environmentLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2010B.-Y. Chen Abstract Aims:, To investigate the susceptibility of 221 Listeria spp. (86 Listeria monocytogenes, 41 Listeria innocua and 94 Listeria seeligeri-Listeria welshimeri-Listeria ivanovii) isolated from catfish fillets and processing environment to 15 antibiotics. Methods and Results:,Listeria isolates were analysed by disc-diffusion assay for their resistance to 15 drugs. All isolates were resistant to cefotaxime and clindamycin but were sensitive to ampicillin, cephalothin, chloramphenicol, erythromycin, gentamycin, kanamycin, rifampin, streptomycin, sulfamethoxazole/trimethoprim and vancomycin. Unlike L. monocytogenes and L. seeligeri-L. welshimeri-L. ivanovii isolates, 22% of L. innocua isolates displayed tetracycline/oxytetracycline resistance. Screening of tet genes by PCR identified tet(M) gene in the chromosome of all tetracycline/oxytetracycline-resistant L. innocua. However, this gene was not associated with the integrase gene of Tn1545. Repetitive extragenic palindromic- and enterobacterial repetitive intergenic consensus-PCR typing methods showed no genotype-specific tetracycline resistance in the tet(M)-positive strains. Conclusions:, Catfish fillets and processing environment were currently free of L. monocytogenes resistant to antibiotics commonly used in human listeriosis treatment. However, the presence of tet(M) gene in L. innocua raises the possibility of future acquisition of resistance by L. monocytogenes. Significance and Impact of the Study:, These data will be helpful in improving background data on antibiotics resistance strains isolated from food and processing environment. [source] Nitrofurantoin quadruple therapy for Helicobacter pylori infection: effect of metronidazole resistanceALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 4 2001D. Y. Graham Background: Antibiotic resistance has increasingly been recognized as the major cause of treatment failure for Helicobacter pylori infection. New therapies for patients with metronidazole- or clarithromycin-resistant H. pylori are needed. Aim: To investigate the role of nitrofurantoin quadruple therapy for the treatment of H. pylori. Methods: Patients with confirmed H. pylori infection received nitrofurantoin (100 mg t.d.s.), omeprazole (20 mg b.d.), Pepto-Bismol (two tablets t.d.s.), and tetracycline (500 mg t.d.s.) for 14 days. Four or more weeks after the end of therapy, outcome was assessed by repeat endoscopy with histology and culture or urea breath testing. Results: Thirty patients were entered, including 25 men and five women; the mean age was 54.9 years. The most common diagnoses were duodenal ulcer (23%) and GERD (18%). The intention-to-treat cure rate was 70% (95% CI: 50.6,85%). Nitrofurantoin quadruple therapy was more effective with metronidazole-sensitive strains (88%; 15 out of 17) than with metronidazole-resistant strains (33%; three out of nine; P=0.008). Two of the treatment failures had pre-treatment isolates susceptible to metronidazole, which were resistant after therapy. Conclusions: Because nitrofurantoin quadruple therapy performed inadequately in the presence of metronidazole resistance, we conclude that nitrofurantoin is unlikely to find clinical utility for the eradication of H. pylori. [source] Screening of herbal extracts against multi-drug resistant Acinetobacter baumanniiPHYTOTHERAPY RESEARCH, Issue 8 2010Yoko Miyasaki Abstract Antibiotic resistance is increasing resulting in a decreasing number of fully active antimicrobial agents available to treat infections with multi-drug resistant (MDR) bacteria. Herbal medicines may offer alternative treatment options. A direct inoculation method simulating the standard disc diffusion assay was developed to determine in vitro antimicrobial activity of sixty herbal extracts against MDR- Acinetobacter baumannii (A. baumannii). Eighteen herbal extracts inhibited MDR- A. baumannii on agar plates, although the magnitude and quality of bacterial inhibition differed considerably among the antibacterial herbal extracts. Next, minimal inhibitory concentration (MIC) of these antibacterial herbal extracts was calculated using a broth microdilution assay. For most herbal extracts, the larger the zone of inhibition on agar plates, the lower the MIC. In general, hetero-resistance on agar plates correlated with higher MIC. The skip well phenomenon was seen with two herbal extracts. In conclusion, 30% of the screened herbal extracts demonstrated in vitro antibacterial activity against MDR- A. baumannii using similar rigorous testing methods as those commonly employed for assessing antimicrobial activity of synthetic antibacterial agents. Characterization of a specific compound conferring this antibacterial activity of the herbal extracts may help to identify novel antimicrobial agents active against highly resistant bacteria. Copyright © 2010 John Wiley & Sons, Ltd. [source] Screening of binding activity of Streptococcus pneumoniae, Streptococcus agalactiae and Streptococcus suis to berries and juicesPHYTOTHERAPY RESEARCH, Issue S1 2010Marko Toivanen Abstract Antiadhesion therapy is a promising approach to the fight against pathogens. Antibiotic resistance and the lack of effective vaccines have increased the search for new methods to prevent infectious diseases. Previous studies have shown the antiadhesion activity of juice from cultivated cranberries (Vaccinium macrocarpon Ait.) against bacteria, especially E. coli. In this study, the binding of two streptococcal strains, Streptococcus pneumoniae and Streptococcus agalactiae, to molecular size fractions (FI, FII and FIII, <10,kDa, 10,100,kDa, and >100,kDa, respectively) of berries and berry and fruit juices from 12 plant species were studied using a microtiter well assay. For Streptococcus suis a hemagglutination inhibition assay was used. In general, binding activity was detected especially to wild cranberry (Vaccinium oxycoccos L.) and to other Vaccinium species. S. pneumoniae cells bound most to cranberry juice fraction FI and S. agalactiae cells to cranberry fraction FIII. Hemagglutination induced by S. suis was most effectively inhibited by cranberry fraction FII. NMR spectra of some characteristic active and non-active fractions were also measured. They indicate that fractions FII and FIII contained proanthocyanidins and/or other phenolic compounds. The results suggest Vaccinium berries as possible sources of antiadhesives against bacterial infections. Copyright © 2009 John Wiley & Sons, Ltd. [source] Latest news and product developmentsPRESCRIBER, Issue 21 2007Article first published online: 3 DEC 200 NSAIDs and SSRIs increase GI bleeding Taking an NSAID and an SSRI increases the risk of GI bleeding more than six-fold compared with taking neither drug, a meta-analysis shows (Aliment Pharmacol Ther online: 5 Oct 2007; doi:10.1111/j.1365-2036.20 07.03541.x). The analysis included four observational studies involving a total of 153 000 patients, and 101 cases reported in postmarketing surveillance. Compared with nonuse, the odds ratio for upper GI haemorrhage in patients taking an SSRI alone was 2.36; the number needed to harm (NNH) was 411 for one year's treatment in patients aged over 50 with no risk factors. For those taking an SSRI and an NSAID, it was 6.33 (NNH 106). Of 22 cases where treatment duration was known, the median time to onset of bleeding was 25 weeks and five occurred within one month. The MHRA warns of this interaction in its latest issue of Drug Safety Update, noting: ,corticosteroids, antiplatelet agents, and SSRIs may increase the risk of GI ulceration or bleeding. NSAIDs may enhance the effects of anticoagulants, such as warfarin'. MHRA warning on NSAID safety The MHRA reminds prescribers of new restrictions on prescribing piroxicam and the risks associated with ketorolac and ketoprofen in its latest Drug Safety Update (2007;1:Issue 3). Treatment with piroxicam should now only be initiated by a specialist as a second-line drug; patients currently taking it should be reviewed at the next routine appointment. Piroxicam is no longer indicated for any acute indications. These restrictions do not apply to topical piroxicam (Feldene gel). Ketorolac and ketoprofen are associated with a higher risk of adverse GI effects than other NSAIDs. The MHRA advises prescribers to adhere to the licensed indications that limit oral ketorolac therapy to seven days (two days for continuous iv or im use) and the maximum dose of ketoprofen to 100-200mg. Inhaled steroids may increase the risk of pneumonia in patients with COPD. In the TORCH study (N Engl J Med 2007;356:775-89), fluticasone (Flixotide) and fluticasone plus salmeterol (Seretide) were associated with a significantly increased risk compared with salmeterol alone. The MHRA recommends vigilance for signs of pneumonia or bronchitis in patients with COPD who are treated with inhaled steroids; affected patients should have their treatment reconsidered. Other issues reviewed in Drug Safety Update include: a more intense reaction after revaccination with the pneumococcal vaccine, Pneumovax II; exacerbation of osteonecrosis of the jaw by dental surgery in patients taking a bisphosphonate; a lower maximum dose for lorazepam (4mg for severe anxiety, 2mg for severe insomnia) rare reactions with botulinum toxin; and the cardiovascular safety and risk of fractures with the glitazones. Antibiotic resistance GPs who reduce their antibiotic prescribing achieve a significant reduction in bacterial resistance, a study from Wales has shown (Br J Gen Pract 2007;57:785-92). The analysis of 164 225 coliform isolates from urine samples submitted from 240 general practices found a 5.2 per cent decrease in ampicillin resistance in practices with the greatest reductions in total antibiotic prescribing. Overall, ampicillin resistance decreased by 1 per cent for every reduction of 50 amoxicillin prescriptions per 1000 patients. Trimethoprim resistance showed a similar trend. Mortality risk with discontinuing statins Patients who discontinue statin therapy after acute stroke are almost three times more likely to die than those who do not, an Italian study shows (Stroke 2007;38:2652-7). Follow-up of 631 patients discharged after acute stroke revealed that 39 per cent discontinued statin therapy. The hazard ratio for all-cause mortality in the first 12 months was 2.78 compared with those who continued treatment; this compared with a hazard ratio of 1.81 for stopping antiplatelet therapy. The authors argue that patient care should be improved during the transition from hospital to outpatient primary care. ACEI ± ARB = ADRs Combining an ACE inhibitor and an angiotensin-II receptor blocker increases the risk of adverse effects in patients with symptomatic left ventricular dysfunction, according to a US study (Arch Intern Med 2007;167:1930-6). Meta-analysis of four trials involving a total of 17 337 patients followed up for about two years showed that, compared with therapy including an ACE inhibitor, combined treatment increased the risk of stopping treatment due to adverse events by 38 per cent in patients with heart failure and by 17 per cent in patients with MI. The authors estimate that, for every 1,000 patients treated, 25 will discontinue treatment due to adverse effects and 17 will develop renal dysfunction. WOSCOPS: statin protection continues Pravastatin reduces the risk of death years after treatment has stopped, according to a follow-up of the WOSCOPS study (N Engl J Med 2007;357:1477-86). The West of Scotland Coronary Prevention Study originally randomised men with hypercholesterolaemia but no history of myocardial infarction (MI) to treatment with pravastatin or placebo. After five years, the combined incidence of death from CHD or nonfatal MI was reduced from 7.9 to 5.5 per cent in the treatment group. During the 10 years after completion of the trial, the incidence of the combined end-point was 8.6 per cent in those originally assigned to pravastatin and 10.3 per cent in the placebo group. All- cause mortality was also reduced over the entire 15-year period. The proportions of patients still taking a statin in the middle of this period, ie five years after the trial ended, were 39 per cent of the placebo group. Prescribing policies on HRT need reappraisal Health authorities should reconsider their policy on prescribing HRT, the International Menopause Society (IMS) says. In an open letter, the IMS says current safety concerns over HRT use are founded, but have been misinterpreted in observational studies, such as the Women's Health Initiative, that led to changes in guidelines. The IMS says HRT is the most effective treatment for vasomotor and urogenital symptoms and the risk:benefit profile is favourable until age 60. Low-dose oestrogen or the transdermal route of administration may lead to a more favourable risk profile. Flu vaccine does cut morbidity and mortality Following The Lancet's commentary doubting the effectiveness of flu vaccination (Lancet Infectious Diseases 2007;7:658-66), a US cohort study has found that it does reduce morbidity and mortality (N Engl J Med 2007;357:1373-81). The observational study included 713 872 person-seasons in older people living in the community over a 10year period from 1990 to 2000. Vaccination was associated with a 48 per cent reduction in the risk of death and a 27 per cent reduction in admission for pneumonia or flu. These benefits changed little in subgroups or with age. Copyright © 2007 Wiley Interface Ltd [source] Macrolide resistance in group A beta haemolytic Streptococcus isolated from outpatient children in LatviaAPMIS, Issue 5 2010DACE ZAVADSKA Zavadska D, B,rzin¸a D, Drukal¸ska L, Puga,ova N¸, Mikla,evi,s E, Gardovska D. Macrolide resistance in group A beta haemolytic Streptococcus isolated from outpatient children in Latvia. APMIS 2010; 118: 366,70. Group A streptococci (GAS) are responsible for up to 30% of cases of pharyngitis in children, and such children do not benefit from treatment with antibiotics. During the last decade, increased resistance to macrolides has emerged as a critical issue in the treatment of GAS pharyngitis. The objective of this study was to determine the antimicrobial resistance of group A beta haemolytic Streptococcus isolated from outpatient children. From 2002 to 2006, 96 GAS strains were obtained from the pharynx of outpatients having symptoms of acute pharyngitis. Antibiotic resistance was determined by disc susceptibility tests according to CLSI standards. The presence of ermA, ermB and mefA was established by the amplification of streptococcal DNA with specific primers. Antimicrobial susceptibility tests revealed that all the strains tested were sensitive to vancomycin, linezolid, penicillin and ceftriaxone. Simultaneously, high levels of resistance to macrolides were evident; 78% of the isolates were resistant to clindamycin and erythromycin. No significant change in the yearly or seasonal incidence of resistance was observed. We describe high antimicrobial resistance of GAS to macrolides in outpatient children (78%), which can be explained by the frequent use of macrolides in the treatment of such individuals. Therefore, macrolides should not be the first drug of choice. [source] Structure and function of GlmU from Mycobacterium tuberculosisACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2009Zhening Zhang Antibiotic resistance is a major issue in the treatment of infectious diseases such as tuberculosis. Existing antibiotics target only a few cellular pathways and there is an urgent need for antibiotics that have novel molecular mechanisms. The glmU gene is essential in Mycobacterium tuberculosis, being required for optimal bacterial growth, and has been selected as a possible drug target for structural and functional investigation. GlmU is a bifunctional acetyltransferase/uridyltransferase that catalyses the formation of UDP-GlcNAc from GlcN-1-P. UDP-GlcNAc is a substrate for two important biosynthetic pathways: lipopolysaccharide and peptidoglycan synthesis. The crystal structure of M. tuberculosis GlmU has been determined in an unliganded form and in complex with GlcNAc-1-P or UDP-GlcNAc. The structures reveal the residues that are responsible for substrate binding. Enzyme activities were characterized by 1H NMR and suggest that the presence of acetyl-coenzyme A has an inhibitory effect on uridyltransferase activity. [source] High-resolution structure of the antibiotic resistance protein NimA from Deinococcus radioduransACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2008Hanna-Kirsti S. Leiros Many anaerobic human pathogenic bacteria are treated using 5-nitroimidazole-based (5-Ni) antibiotics, a class of inactive prodrugs that contain a nitro group. The nitro group must be activated in an anaerobic one-electron reduction and is therefore dependent on the redox system in the target cells. Antibiotic resistance towards 5-Ni drugs is found to be related to the nim genes (nimA, nimB, nimC, nimD, nimE and nimF), which are proposed to encode a reductase that is responsible for converting the nitro group of the antibiotic into a nonbactericidal amine. A mechanism for the Nim enzyme has been proposed in which two-electron reduction of the nitro group leads to the generation of nontoxic derivatives and confers resistance against these antibiotics. The cofactor was found to be important in the mechanism and was found to be covalently linked to the reactive His71. In this paper, the 1.2,Å atomic resolution crystal structure of the 5-nitroimidazole antibiotic resistance protein NimA from Deinococcus radiodurans (DrNimA) is presented. A planar cofactor is clearly visible and well defined in the electron-density map adjacent to His71, the identification of the cofactor and its properties are discussed. [source] New developments in carbapenemsCLINICAL MICROBIOLOGY AND INFECTION, Issue 12 2008J. N. Kattan Abstract Antibiotic resistance among Gram-negative pathogens in hospitals is a growing threat to patients and is driving the increased use of carbapenems. Carbapenems are potent members of the ,-lactam family of antibiotics, with a history of safety and efficacy for serious infections that exceeds 20 years. Original and review articles were identified from a Medline search (1979,2008). Reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and package inserts were also used. Carbapenems are effective in treating severe infections at diverse sites, with relatively low resistance rates and a favourable safety profile. Carbapenems are the ,-lactams of choice for the treatment of infections caused by multidrug-resistant organisms. Optimized dosing of carbapenems should limit the emergence of resistance and prolong the utility of these agents. The newly approved doripenem should prove to be a valuable addition to the currently available carbapenems: imipenem, meropenem and ertapenem. [source] Antibiotic resistance , from pathogen to disease surveillanceCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2002R. Finch Surveillance is central to defining the epidemiology of antibiotic resistance, developing new strategies for its control, informing disease management, identifying targets for new drugs and vaccines and in turn, evaluating and refining the impact of these interventions. Current surveillance systems often fall short of this ideal. Since antibiotics are prescribed for the treatment of specific disease, surveillance that reliably links diagnosis, pathogen and antibiotic usage is likely to be more informative. By identifying diseases that are readily recognized, and are usually reliably defined microbiologically, and in turn have clear links to public-health issues, a broader ownership of surveillance data should result. The case is argued for a more disease-focused microbiological surveillance approach than exists at present. Examples are provided which reflect a cross-section of community, nosocomial, zoonotic and imported infectious disease challenges, and where new approaches are urgently required to combat the upward spiral of resistance. [source] Prevention of pneumococcal disease in children.ACTA PAEDIATRICA, Issue 5 2001Pneumococcal conjugate vaccines: their use globally could have a major impact on public health Pneumococcal disease is a major cause of morbidity and mortality in infants and young children worldwide. New pneumococcal conjugate vaccines include 7 to 11 serotypes, which are the most common cause of paediatric disease in most parts of the world. The efficacy of a 7-valent conjugate vaccine was 97.4% (95% CI, 82.7,99.9) against invasive pneumococcal disease, and 57% (95% CI, 44,67) against otitis media, caused by vaccine serotypes. Evidence shows that the vaccine has the potential to prevent pneumonia. Pneumococcal conjugate vaccination has also been shown to reduce nasopharyngeal carriage of vaccine serotypes (particularly serotypes associated with antibiotic resistance). Thus widespread use of pneumococcal conjugate vaccine could substantially reduce the burden of invasive disease and would have the potential to control the global spread of antibiotic resistance in pneumococci. Conclusion: It is important that these highly effective vaccines should be made available to children in the developing countries. [source] Gastrointestinal Bacterial Transmission among Humans, Mountain Gorillas, and Livestock in Bwindi Impenetrable National Park, UgandaCONSERVATION BIOLOGY, Issue 6 2008INNOCENT B. RWEGO ecología de enfermedades; Escherichia coli; primates; salud del ecosistema; zoonosis Abstract:,Habitat overlap can increase the risks of anthroponotic and zoonotic pathogen transmission between humans, livestock, and wild apes. We collected Escherichia coli bacteria from humans, livestock, and mountain gorillas (Gorilla gorilla beringei) in Bwindi Impenetrable National Park, Uganda, from May to August 2005 to examine whether habitat overlap influences rates and patterns of pathogen transmission between humans and apes and whether livestock might facilitate transmission. We genotyped 496 E. coli isolates with repetitive extragenic palindromic polymerase chain reaction fingerprinting and measured susceptibility to 11 antibiotics with the disc-diffusion method. We conducted population genetic analyses to examine genetic differences among populations of bacteria from different hosts and locations. Gorilla populations that overlapped in their use of habitat at high rates with people and livestock harbored E. coli that were genetically similar to E. coli from those people and livestock, whereas E. coli from gorillas that did not overlap in their use of habitats with people and livestock were more distantly related to human or livestock bacteria. Thirty-five percent of isolates from humans, 27% of isolates from livestock, and 17% of isolates from gorillas were clinically resistant to at least one antibiotic used by local people, and the proportion of individual gorillas harboring resistant isolates declined across populations in proportion to decreasing degrees of habitat overlap with humans. These patterns of genetic similarity and antibiotic resistance among E. coli from populations of apes, humans, and livestock indicate that habitat overlap between species affects the dynamics of gastrointestinal bacterial transmission, perhaps through domestic animal intermediates and the physical environment. Limiting such transmission would benefit human and domestic animal health and ape conservation. Resumen:,El traslape de hábitats puede incrementar los riesgos de transmisión de patógenos antroponótica y zoonótica entre humanos, ganado y simios silvestres. Recolectamos bacterias Escherichia coli de humanos, ganado y gorilas de montaña (Gorilla gorilla beringei) en el Parque Nacional Bwindi Impenetrable, Uganda, de mayo a agosto 2005 para examinar sí el traslape de hábitat influye en las tasas y patrones de transmisión de patógenos entre humanos y simios y sí el ganado facilita esa transmisión. Determinamos el genotipo de 496 aislados de E. coli con marcaje de reacción en cadena de polimerasa palindrómica extragénica (rep-PCR) y medimos la susceptibilidad a 11 antibióticos con el método de difusión de disco. Realizamos análisis de genética poblacional para examinar las diferencias genéticas entre poblaciones de bacterias de huéspedes y localidades diferentes. Las poblaciones de gorilas con alto grado de traslape en el uso de hábitat con humanos y ganado presentaron E. coli genéticamente similar a E. coli de humanos y ganado, mientras que E. coli de gorilas sin traslape en el uso hábitat con humanos y ganado tuvo relación lejana con las bacterias de humanos y ganado. Treinta y cinco porciento de los aislados de humanos, 27% de los aislados de ganado y 17% de los aislados de gorilas fueron clínicamente resistentes a por lo menos un antibiótico utilizado por habitantes locales, y la proporción de gorilas individuales con presencia de aislados resistentes declinó en las poblaciones proporcionalmente con la disminución en el grado de traslape con humanos. Estos de patrones de similitud genética y resistencia a antibióticos entre E. coli de poblaciones de simios, humanos y ganado indican que el traslape de hábitat entre especies afecta la dinámica de transmisión de bacterias gastrointestinales, probablemente a través de animales domésticos intermediarios y el ambiente físico. La limitación de esa transmisión beneficiaría a la salud de humanos y animales domésticos y a la conservación de simios. [source] New and emerging treatments in dermatology: acneDERMATOLOGIC THERAPY, Issue 2 2008A. Katsambas ABSTRACT:, Topical retinoids, benzoyl peroxide, azelaic acid, and topical and oral antibiotics remain the milestone of treatment for mild to moderate acne vulgaris. Oral isotretinoin is useful for the treatment of severe nodular acne, treatment-resistant acne, and acne with a risk of physical or psychological scarring. Hormonal treatment in female acne is useful in resistant or late-onset acne. With increasing concerns regarding teratogenicity of isotretinoin and increasing antibiotic resistance, there is a clear need for therapeutic alternatives to these long-used treatments. Research in the pathogenesis of acne has allowed for new therapies and future perspectives regarding acne to evolve. They include low-dose long-term isotretinoin regimens, insulin-sensitizing agents, 5,-reductase type 1 inhibitors, topical photodynamic therapy, new combination formulations, dietary interventions, and antiinflammatory agents such as lipoxygenase inhibitors. [source] Coevolution of antibiotic production and counter-resistance in soil bacteriaENVIRONMENTAL MICROBIOLOGY, Issue 3 2010Paris Laskaris Summary We present evidence for the coexistence and coevolution of antibiotic resistance and biosynthesis genes in soil bacteria. The distribution of the streptomycin (strA) and viomycin (vph) resistance genes was examined in Streptomyces isolates. strA and vph were found either within a biosynthetic gene cluster or independently. Streptomyces griseus strains possessing the streptomycin cluster formed part of a clonal complex. All S. griseus strains possessing solely strA belonged to two clades; both were closely related to the streptomycin producers. Other more distantly related S. griseus strains did not contain strA. S. griseus strains with only vph also formed two clades, but they were more distantly related to the producers and to one another. The expression of the strA gene was constitutive in a resistance-only strain whereas streptomycin producers showed peak strA expression in late log phase that correlates with the switch on of streptomycin biosynthesis. While there is evidence that antibiotics have diverse roles in nature, our data clearly support the coevolution of resistance in the presence of antibiotic biosynthetic capability within closely related soil dwelling bacteria. This reinforces the view that, for some antibiotics at least, the primary role is one of antibiosis during competition in soil for resources. [source] Coselection for microbial resistance to metals and antibiotics in freshwater microcosmsENVIRONMENTAL MICROBIOLOGY, Issue 9 2006Ramunas Stepanauskas Summary Bacterial resistances to diverse metals and antibiotics are often genetically linked, suggesting that exposure to toxic metals may select for strains resistant to antibiotics and vice versa. To test the hypothesis that resistances to metals and antibiotics are coselected for in environmental microbial assemblages, we investigated the frequency of diverse resistances in freshwater microcosms amended with Cd, Ni, ampicillin or tetracycline. We found that all four toxicants significantly increased the frequency of bacterioplankton resistance to multiple, chemically unrelated metals and antibiotics. An ampicillin-resistant strain of the opportunistic human pathogen Ralstonia mannitolilytica was enriched in microcosms amended with Cd. Frequencies of antibiotic resistance were elevated in microcosms with metal concentrations representative of industry and mining-impacted environments (0.01,1 mM). Metal but not antibiotic amendments decreased microbial diversity, and a weeklong exposure to high concentrations of ampicillin (0.01,10 mg l,1) and tetracycline (0.03,30 mg l,1) decreased microbial abundance only slightly, implying a large reservoir of antibiotic resistance in the studied environment. Our results provide first experimental evidence that the exposure of freshwater environments to individual metals and antibiotics selects for multiresistant microorganisms, including opportunistic human pathogens. [source] Worldwide distribution of Pseudomonas aeruginosa clone C strains in the aquatic environment and cystic fibrosis patientsENVIRONMENTAL MICROBIOLOGY, Issue 7 2005Ute Römling Summary Highly successful bacterial clones have the ability to effectively colonize environmental niches and patients. However, the factors which determine the complex interplay between the colonization of environmental niches and patients are mainly unknown. In this study we show that Pseudomonas aeruginosa clone C strains are distributed worldwide and highly prone to infect cystic fibrosis (CF) patients in Canada, England, France and Germany. In Hanover, Germany and Vancouver, Canada, clone C strains are highly prevalent in the CF patient community, although the mechanisms of acquisition may have been different. All clone C strains showed highly related macrorestriction fragment pattern of the whole genome as visualized by pulsed-field gel electrophoresis and harboured the 102 kbp plasmid pKLC102. Comparison of three prevalent P. aeruginosa clones with different distribution between the environment and patients revealed that neither enhanced biofilm formation nor antibiotic resistance was responsible for the spread of clone C. Clone M, which was highly prevalent in the clinical environment such as sanitary facilities, lacked motility, which could explain its relatively low prevalence in CF patients. Elucidation of the mechanisms which lead to the prevalence of clone C strain in patients and the environment requires the investigation of additional phenotypes. [source] Analysis of the Pseudomonas aeruginosa oprD gene from clinical and environmental isolatesENVIRONMENTAL MICROBIOLOGY, Issue 12 2002Jean-Paul Pirnay Summary Genomes are constantly evolving. Our report highlights the wide mutational diversity of clinical as well as environmental isolates, compared with the laboratory strain(s), through the systematic genetic analysis of a chromosomal porin gene (oprD) in relation to a specific antibiotic resistance. Mutational inactivation of the oprD gene is associated with carbapenem resistance in Pseudomonas aeruginosa. The sequence of the oprD gene of 55 Pseudomonas aeruginosa natural isolates obtained from across the world , from sources as diverse as patients and rhizospheres , was analysed. A microscale mosaic structure for this gene , resulting from multiple intra- and possibly interspecies recombinational events , is reported. An array of independent and seemingly fast-occurring defective oprD mutations were found, none of which had been described before. A burn wound isolate demonstrated unusually high overall sequence variability typical of mutator strains. We also present evidence for the existence of OprD homologues in other fluorescent pseudomonads. [source] Studies on structural and functional divergence among seven WhiB proteins of Mycobacterium tuberculosis H37RvFEBS JOURNAL, Issue 1 2009Md. Suhail Alam The whiB -like genes (1-7) of Mycobacterium tuberculosis are involved in cell division, nutrient starvation, pathogenesis, antibiotic resistance and stress sensing. Although the biochemical properties of WhiB1, WhiB3 and WhiB4 are known, there is no information about the other proteins. Here, we elucidate in detail the biochemical and biophysical properties of WhiB2, WhiB5, WhiB6 and WhiB7 of M. tuberculosis and present a comprehensive comparative study on the molecular properties of all WhiB proteins. UV,Vis spectroscopy has suggested the presence of a redox-sensitive [2Fe,2S] cluster in each of the WhiB proteins, which remains stably bound to the proteins in the presence of 8 m urea. The [2Fe,2S] cluster of each protein was oxidation labile but the rate of cluster loss decreased under reducing environments. The [2Fe,2S] cluster of each WhiB protein responded differently to the oxidative effect of air and oxidized glutathione. In all cases, disassembly of the [2Fe,2S] cluster was coupled with the oxidation of cysteine-thiols and the formation of two intramolecular disulfide bonds. Both CD and fluorescence spectroscopy revealed that WhiB proteins are structurally divergent members of the same family. Similar to WhiB1, WhiB3 and WhiB4, apo WhiB5, WhiB6 and WhiB7 also reduced the disulfide of insulin, a model substrate. However, the reduction efficiency varied significantly. Surprisingly, WhiB2 did not reduce the insulin disulfide, even though its basic properties were similar to those of others. The structural and functional divergence among WhiB proteins indicated that each WhiB protein is a distinguished member of the same family and together they may represent a novel redox system for M. tuberculosis. [source] Characterization of DNA transport in the thermophilic bacterium Thermus thermophilus HB27FEBS JOURNAL, Issue 18 2006Cornelia Schwarzenlander Horizontal gene transfer has been a major force for genome plasticity over evolutionary history, and is largely responsible for fitness-enhancing traits, including antibiotic resistance and virulence factors. In particular, for adaptation of prokaryotes to extreme environments, lateral gene transfer seems to have played a crucial role. Recently, by performing a genome-wide mutagenesis approach with Thermus thermophilus HB27, we identified the first genes in a thermophilic bacterium for the uptake of free DNA, a process called natural transformation. Here, we present the first data on the biochemistry and bioenergetics of the DNA transport process in this thermophile. We report that linear and circular plasmid DNA are equally well taken up with a high maximal velocity of 1.5 µg DNA·(mg protein),1·min,1, demonstrating an extremely efficient binding and uptake rate of 40 kb·s,1·cell,1. Uncouplers and ATPase inhibitors immediately inhibited DNA uptake, providing clear evidence that DNA translocation in HB27 is an energy-dependent process. DNA uptake studies with genomic DNA of Bacteria, Archaea and Eukarya revealed that Thermus thermophilus HB27 takes up DNA from members of all three domains of life. We propose that the extraordinary broad substrate specificity of the highly efficient Thermus thermophilus HB27 DNA uptake system may contribute significantly to thermoadaptation of Thermus thermophilus HB27 and to interdomain DNA transfer in hot environments. [source] Survey of antibiotic resistance in an integrated marine aquaculture system under oxolinic acid treatmentFEMS MICROBIOLOGY ECOLOGY, Issue 3 2006Etienne Giraud Abstract The consequences of antibiotic use in aquatic integrated systems, which are based on trophic interactions between different cultured organisms and physical continuity through water, need to be examined. In this study, fish reared in a prototype marine integrated system were given an oxolinic acid treatment, during and after which the level of resistance to this quinolone antibiotic was monitored among vibrio populations from the digestive tracts of treated fish, co-cultured bivalves and sediments that were isolated on thiosulfate,citrate,bile,sucrose. Oxolinic acid minimum inhibitory concentration distributions obtained from replica plating of thiosulfate,citrate,bile,sucrose plates indicated that a selection towards oxolinic acid resistance had occurred in the intestines of fish under treatment. In contrast, and despite oxolinic acid concentrations higher than minimum inhibitory concentrations of susceptible bacteria, no clear evolution of resistance levels was detected either in bivalves or in sediments. [source] Characterization of potential stress responses in ancient Siberian permafrost psychroactive bacteriaFEMS MICROBIOLOGY ECOLOGY, Issue 1 2005Monica A. Ponder Abstract Past studies of cold-acclimated bacteria have focused primarily on organisms not capable of sub-zero growth. Siberian permafrost isolates Exiguobacterium sp. 255-15 and Psychrobacter sp. 273-4, which grow at subzero temperatures, were used to study cold-acclimated physiology. Changes in membrane composition and exopolysaccharides were defined as a function of growth at 24, 4 and ,2.5 °C in the presence and absence of 5% NaCl. As expected, there was a decrease in fatty acid saturation and chain length at the colder temperatures and a further decrease in the degree of saturation at higher osmolarity. A shift in carbon source utilization and antibiotic resistance occurred at 4 versus 24 °C growth, perhaps due to changes in the membrane transport. Some carbon substrates were used uniquely at 4 °C and, in general, increased antibiotic sensitivity was observed at 4 °C. All the permafrost strains tested were resistant to long-term freezing (1 year) and were not particularly unique in their UVC tolerance. Most of the tested isolates had moderate ice nucleation activity, and particularly interesting was the fact that the Gram-positive Exiguobacterium showed some soluble ice nucleation activity. In general the features measured suggest that the Siberian organisms have adapted to the conditions of long-term freezing at least for the temperatures of the Kolyma region which are ,10 to ,12 °C where intracellular water is likely not frozen. [source] Intramembrane-sensing histidine kinases: a new family of cell envelope stress sensors in Firmicutes bacteriaFEMS MICROBIOLOGY LETTERS, Issue 2 2006Thorsten Mascher Abstract Two-component signal-transducing systems (TCS) consist of a histidine kinase (HK) that senses a specific environmental stimulus, and a cognate response regulator (RR) that mediates the cellular response. Most HK are membrane-anchored proteins harboring two domains: An extracytoplasmic input and a cytoplasmic transmitter (or kinase) domain, separated by transmembrane helices that are crucial for the intramolecular information flow. In contrast to the cytoplasmic domain, the input domain is highly variable, reflecting the plethora of different signals sensed. Intramembrane-sensing HK (IM-HK) are characterized by their short input domain, consisting solely of two putative transmembane helices. They lack an extracytoplasmic domain, indicative for a sensing process at or from within the membrane interface. Most proteins sharing this domain architecture are found in Firmicutes bacteria. Two major groups can be differentiated based on sequence similarity and genomic context: (1) BceS-like IM-HK that are functionally and genetically linked to ABC transporters, and (2) LiaS-like IM-HK, as part of three-component systems. Most IM-HK sense cell envelope stress, and identified target genes are often involved in maintaining cell envelope integrity, mediating antibiotic resistance, or detoxification processes. Therefore, IM-HK seem to constitute an important mechanism of cell envelope stress response in low G+C Gram-positive bacteria. [source] Predicting the emergence of resistance to antifungal drugsFEMS MICROBIOLOGY LETTERS, Issue 1 2001Leah E Cowen Abstract The emergence of antifungal drug resistance is inevitable. Here I discuss antibiotic resistance in the context of the adaptive potential of fungi and I propose an approach to predicting the evolution of antifungal resistance using experimental evolution of DNA sequences and microbial populations. Prediction is based on determination of evolutionary potential at two levels, the gene and the genome. At the level of the gene, evolutionary potential depends on the sequence space of candidate resistance genes defined by the fitness effects of all possible mutations in all possible combinations. At the level of the genome, evolutionary potential depends on the adaptive landscape defined by the fitness effects of all possible interactions among alleles constituting the genotype. [source] | ||||||||||||||||||||||||||||||||||