Spread Of Antibiotic-resistant Bacteria Research Articles

Computational redesign of bacterial biotin carboxylase inhibitors using structure-based virtual screening of combinatorial libraries.

As the spread of antibiotic resistant bacteria steadily increases, there is an urgent need for new antibacterial agents. Because fatty acid synthesis is only used for membrane biogenesis in bacteria, the enzymes in this pathway are attractive targets for antibacterial agent development. Acetyl-CoA carboxylase catalyzes the committed and regulated step in fatty acid synthesis. In bacteria, the enzyme is composed of three distinct protein components: biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase. Fragment-based screening revealed that amino-oxazole inhibits biotin carboxylase activity and also exhibits antibacterial activity against Gram-negative organisms. In this report, we redesigned previously identified lead inhibitors to expand the spectrum of bacteria sensitive to the amino-oxazole derivatives by including Gram-positive species. Using 9,411 small organic building blocks, we constructed a diverse combinatorial library of 1.2 × 108 amino-oxazole derivatives. A subset of 9 × 106 of these compounds were subjected to structure-based virtual screening against seven biotin carboxylase isoforms using similarity-based docking by eSimDock. Potentially broad-spectrum antibiotic candidates were selected based on the consensus ranking by several scoring functions including non-linear statistical models implemented in eSimDock and traditional molecular mechanics force fields. The analysis of binding poses of the top-ranked compounds docked to biotin carboxylase isoforms suggests that: (1) binding of the amino-oxazole anchor is stabilized by a network of hydrogen bonds to residues 201, 202 and 204; (2) halogenated aromatic moieties attached to the amino-oxazole scaffold enhance interactions with a hydrophobic pocket formed by residues 157, 169, 171 and 203; and (3) larger substituents reach deeper into the binding pocket to form additional hydrogen bonds with the side chains of residues 209 and 233. These structural insights into drug-biotin carboxylase interactions will be tested experimentally in in vitro and in vivo systems to increase the potency of amino-oxazole inhibitors towards both Gram-negative as well as Gram-positive species.

English

Drug resistant Escherichia coli persist in the intestinal flora of poultry birds, and these serve as route via which they can be transmitted directly to humans, thus contributing to the already growing crisis of antibiotic resistance. The purpose of this study was to determine the cloacal feacal carriage and occurrence of antibiotic resistant E. coli isolates from chicken fed with and without antibiotic supplemented feeds. Cloacal feacal swabs (n = 200) were aseptically obtained from two poultry farms in Abakaliki metropolis, Ebonyi state of Nigeria, and these were inoculated on MacConkey and cystine-lactose-electrolyte-deficient (CLED) media and incubated at 37°C for 18 to 24 h. Suspected colonies of E. coli growing on the agar media were subcultured, purified and further characterized using standard microbiology techniques. Antibiogram was investigated using the Kirby-Bauer disk diffusion method as per the clinical laboratory standards institute (CLSI) criteria. A total of 45 E. coli was isolated from the 200 cloacal feacal swab samples used for this study. Overall, 28% of E. coli were isolated from chicken fed with feed supplemented with antibiotics while only 17% of E. coli was isolated from chicken that received feed without antibiotics supplements. All the E. coli isolates showed varying rates of resistance and susceptibility to the tested antibiotics. Our results strongly reveal the occurrence of antibiotic resistant E. coli from chicken fed with and without antibiotic supplemented feeds. It is very critical that the continuous use of antibiotics in poultry production be strictly monitored, controlled and discouraged in order to contain the emergence and spread of antibiotic resistant bacteria through poultry production. Key words: Resistance, Escherichia coli, poultry, veterinary, Nigeria.

Urban Wastewater as Hotspot for Antibiotic and Antibiotic Resistant Bacteria Spread into the Aquatic Environment

Urban Wastewater as Hotspot for Antibiotic and Antibiotic Resistant Bacteria Spread into the Aquatic Environment

Can Gloves and Gowns Prevent the Spread of Antibiotic-Resistant Bacteria?

Hospitals are now taking multiple approaches to prevent the spread of antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus

Abundance of class 1–3 integrons in South Carolina estuarine ecosystems under high and low levels of anthropogenic influence

The impact of human activity on the spread of antibiotic resistant bacteria throughout coastal estuarine ecosystems is not well characterized. It has been suggested that laterally transferred genetic agents, such as integrons, play a role in the spread of resistant bacteria throughout ecosystems. This study compares the distribution of three integron classes throughout a coastal estuarine ecosystem. To determine integron distribution patterns, DNA was extracted from sediment and water collected at seven sites throughout two estuaries with different levels of anthropogenic input and integrons analyzed using quantitative PCR. The data show that while all three integron classes are present, the relative abundance is different, with class 2 integrons significantly elevated in areas of high anthropogenic input and class 1 integrons elevated in areas of low input. Our results provide a foundation for using integron gene distribution as a biomarker of urban impact on antibiotic resistance gene flow and ecosystem health.

Antibiotic resistant Escherichia coli in hospital and municipal sewage and their emission to the environment

The spreading of antibiotic resistant bacteria in the environment is a threat to human health but little is known about the transmission of extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli from the hospital and municipal sewage to the water basin and to the air at the WWTPs (Waste Water Treatment Plants) area and their surroundings. Accordingly, it seems particularly interesting to trace the fate of these bacteria and their genes encoding antibiotic resistance in both untreated sewage from hospitals, and in sewage after different stages of purification, and finally to examine the degree of their emissions to environment. Although wastewater treatment processes reduce number of bacteria in sewage up to 99%, in the presented study it was reported that more than 2.7×103 CFU/mL E. coli reached the receiving water and contributed to dissemination of resistant bacteria into the environment. We received 395 E. coli strains from sewage and environmental samples and we investigated their antibiotic susceptibility and the presence of bla gene encoding TEM, CTX, OXA and SHV. From among 167 and 147 E. coli strains isolated from hospital effluents and municipal sewage in Olsztyn, Poland, up to 37.1% and 17.7%, respectively, were ESBL-positive. From among 38 and 43 strains isolated from river water and the air up to 18.4% and 27.9%, respectively, were ESBL-producers. The blaCTX-M (blaCTX-M-1, blaCTX-M-3, blaCTX-M-5, blaCTX-M-15) genes were the predominant group of the plasmid-coded ESBLs. More than 38% out of ESBL-producing isolates carried several bla genes. The multiple-antibiotic-resistant (MAR) indexes for ESBL-positive were higher than for ESBL-negative isolates and ranged from 0.45 to 0.63. The MAR indexes for E. coli from hospital effluents and air samples were greater than the indexes calculated for strains isolated from other samples. Presumably, the preliminary disinfection of hospital sewage before its inflow into the sewage system might minimize the spreading of antibiotic-resistant bacteria to the environment.

Meropenem: a potent drug against superbug as unveiled through bioinformatics approaches

Global spread of multi-drug resistant bacteria like Klebsiella pneumoniae and Escherichia coli have raised the alarm for researchers and doctors throughout the world. This new mechanism of resistance and the ability of ndm-1 gene to be transferred between the species may end the era of antibiotics treatment. Carbapenems are reliable drugs against many multi-resistant gram-negative pathogens. A 3-D homology model of NDM-1 was built and analysed for elucidation of functional site and binding interactions. This study revealed that meropenem has good interaction with the active sites of the receptor that could retard the spread of antibiotic resistant bacteria.

Effects of Therapeutical and Reduced Levels of Antibiotics on the Fraction of Antibiotic-Resistant Strains of Escherichia coli in the Chicken Gut

Development of antibiotic resistance in the microbiota of farm animals and spread of antibiotic-resistant bacteria in the agricultural sector not only threaten veterinary use of antibiotics, but jeopardize human health care as well. The effects of exposure to antibiotics on spread and development of antibiotic resistance in Escherichia coli from the chicken gut were studied. Groups of 15 pullets each were exposed under strictly controlled conditions to a 2-day course of amoxicillin, oxytetracycline, or enrofloxacin, added to the drinking water either at full therapeutic dose, 75% of that, or at the carry-over level of 2.5%. During treatment and for 12 days afterwards, the minimal inhibitory concentration (MIC) for the applied antibiotics of E. coli strains isolated from cloacal swabs was measured. The full therapeutic dose yielded the highest percentage of resistant strains during and immediately after exposure. After 12 days without antibiotics, only strains from chickens that were given amoxicillin were significantly more often resistant than the untreated control. Strains isolated from pullets exposed to carry-over concentrations were only for a few days more often resistant than those from the control. These results suggest that, if chickens must be treated with antibiotics, a short intensive therapy is preferable. Even short-term exposure to carry-over levels of antibiotics can be a risk for public health, as also under those circumstances some selection for resistance takes place.

Integron Involvement in Environmental Spread of Antibiotic Resistance

The spread of antibiotic-resistant bacteria is a growing problem and a public health issue. In recent decades, various genetic mechanisms involved in the spread of resistance genes among bacteria have been identified. Integrons – genetic elements that acquire, exchange, and express genes embedded within gene cassettes (GC) – are one of these mechanisms. Integrons are widely distributed, especially in Gram-negative bacteria; they are carried by mobile genetic elements, plasmids, and transposons, which promote their spread within bacterial communities. Initially studied mainly in the clinical setting for their involvement in antibiotic resistance, their role in the environment is now an increasing focus of attention. The aim of this review is to provide an in-depth analysis of recent studies of antibiotic-resistance integrons in the environment, highlighting their potential involvement in antibiotic-resistance outside the clinical context. We will focus particularly on the impact of human activities (agriculture, industries, wastewater treatment, etc.).

Antibiotic resistant bacteria/genes dissemination in lacustrine sediments highly increased following cultural eutrophication of Lake Geneva (Switzerland)

This study investigates faecal indicator bacteria (FIB), multiple antibiotic resistant (MAR), and antibiotic resistance genes (ARGs), of sediment profiles from different parts of Lake Geneva (Switzerland) over the last decades. MARs consist to expose culturable Escherichia coli (EC) and Enterococcus (ENT) to mixed five antibiotics including Ampicillin, Tetracycline, Amoxicillin, Chloramphenicol and Erythromycin. Culture-independent is performed to assess the distribution of ARGs responsible for , β-lactams ( blaTEM; Amoxicillin/Ampicillin) , Streptomycin/Spectinomycin ( aadA) , Tetracycline ( tet) Chloramphenicol ( cmlA) and Vancomycin ( van). Bacterial cultures reveal that in the sediments deposited following eutrophication of Lake Geneva in the 1970s, the percentage of MARs to five antibiotics varied from 0.12% to 4.6% and 0.016% to 11.6% of total culturable EC and ENT, respectively. In these organic-rich bacteria-contaminated sediments, the blaTEM resistant of FIB varied from 22% to 48% and 16% to 37% for EC and ENT respectively, whereas the positive PCR assays responsible for tested ARGs were observed for EC, ENT, and total DNA from all samples. The aadA resistance gene was amplified for all the sediment samples, including those not influenced by WWTP effluent water. Our results demonstrate that bacteria MARs and ARGs highly increased in the sediments contaminated with WWTP effluent following the cultural eutrophication of Lake Geneva. Hence, the human-induced changing limnological conditions highly enhanced the sediment microbial activity, and therein the spreading of antibiotic resistant bacteria and genes in this aquatic environment used to supply drinking water in a highly populated area. Furthermore, the presence of the antibiotic resistance gene aadA in all the studied samples points out a regional dissemination of this emerging contaminant in freshwater sediments since at least the late nineteenth century.

Procalcitonin-guided antibiotic therapy for chronic obstructive pulmonary disease exacerbations

The aim of this article is to review the current literature examining the use of procalcitonin-guided antibiotic therapy for management of chronic obstructive pulmonary disease (COPD) exacerbations. Procalcitonin is a serum marker that rises in response to bacterial infections, but remains low in nonbacterial infections and other proinflammatory conditions. To date, there are four randomized clinical trials which compare procalcitonin-guided antibiotic therapy to standard therapy in patients with COPD exacerbations. In all four trials the use of procalcitonin was associated with a reduction in antibiotic use (prescription and/or duration) without an increase in the rates of adverse patient outcomes including death, admission to the intensive care unit, re-exacerbation and readmission to the hospital. This data is clinically significant and suggests that the use of procalcitonin-guided antibiotic therapy has the potential to decrease unnecessary antibiotic use in nonbacterial COPD exacerbations, thereby curtailing the spread of antibiotic-resistant bacteria, reducing antibiotic-related adverse reactions, including Clostridium difficile infection, and potentially reducing healthcare costs.

Sewage sludge and liquid pig manure as possible sources of antibiotic resistant bacteria

Within the last decades, the environmental spread of antibiotic resistant bacteria has become a topic of concern. In this study, liquid pig manure (n=305) and sewage sludge (n=111) - used as agricultural fertilizers between 2002 and 2005 - were investigated for the presence of Escherichia coli, Enterococcus faecalis and Enterococcus faecium. Bacteria were tested for their resistance against 40 chemotherapeutics including several "reserve drugs". E. coli (n=613) from pig manure were at a significantly higher degree resistant to streptomycin, doxycycline, spectinomycin, cotrimoxazole, and chloramphenicol than E. coli (n=116) from sewage sludge. Enterococci (Ent. faecalis, n=387, and Ent. faecium, n=183) from pig manure were significantly more often resistant to high levels of doxycycline, rifampicin, erythromycin, and streptomycin than Ent. faecalis (n=44) and Ent. faecium (n=125) from sewage sludge. Significant differences in enterococcal resistance were also seen for tylosin, chloramphenicol, gentamicin high level, fosfomycin, clindamicin, enrofloxacin, moxifloxacin, nitrofurantoin, and quinupristin/dalfopristin. By contrast, aminopenicillins were more effective in enterococci from pig manure, and mean MIC-values of piperacillin+tazobactam and third generation cefalosporines were significantly lower in E. coli from pig manure than in E. coli from sewage sludge. 13.4% (E. coli) to 25.3% (Ent. faecium) of pig manure isolates were high-level multiresistant to substances from more than three different classes of antimicrobial agents. In sewage sludge, high-level-multiresistance reached from 0% (Ent. faecalis) to 16% (Ent. faecium). High rates of (multi-) resistant bacteria in pig manure emphasize the need for a prudent - cautious - use of antibiotics in farm animals.

Transmission of a Klebsiella pneumoniae clone harbouring genes for CTX-M-15-like and SHV-112 enzymes in a neonatal intensive care unit of a Kuwaiti hospital

The spread of antibiotic-resistant bacteria has become a large problem in most countries including Kuwait. This antibiotic resistance is usually due to the production of extended-spectrum beta-lactamase (ESBL) enzymes such as SHV, TEM and CTX-M. This study reports the emergence and spread of an ESBL-producing Klebsiella pneumoniae clone in a neonatal intensive care unit (NICU) in a Kuwaiti hospital. Eight ESBL-producing K. pneumoniae isolates were from blood cultures of seven neonates, and two were from the fingers of two healthcare workers in a NICU in Al Jahra Hospital, Kuwait. All isolates were obtained in February-March 2006, except for one, which was obtained in August 2005. Identification of the bacteria was based on traditional bacteriological and biochemical tests using the Vitek system. Antibiotic susceptibility was tested by the disc diffusion method using 16 different antibiotics. ESBLs were detected using disc approximation and double-disc synergy methods and confirmed as ESBLs using Etest. PCR and DNA sequencing were performed to determine the genotypes and mutations in the beta-lactamase genes (blaTEM, blaSHV and blaCTX-M). Genetic relatedness was determined by PFGE. All isolates were confirmed to have ESBLs by the Vitek system, disc approximation test, double-disc diffusion test and Etest, being resistant to cefotaxime, ceftazidime, cefepime, gentamicin, tobramycin and ciprofloxacin but susceptible to tetracycline and trimethoprim-sulfamethoxazole. Molecular studies showed the isolates to have TEM-1 beta-lactamase, a CTX-M-15-like ESBL and the newly discovered SHV-112 ESBL. PFGE showed that all isolates had identical banding patterns. The results indicate that a single clone of ESBL-producing K. pneumoniae caused bloodstream infections among babies in a NICU of a Kuwaiti hospital, and may have emerged at least 5 years ago. This clone was also present on the hands of healthcare workers, suggesting that they may have been involved in its transmission. Further studies are recommended to determine whether this clone is also spreading in other Kuwaiti hospitals.

Prevalence of Antibiotic Resistance in Drinking Water Treatment and Distribution Systems

The occurrence and spread of antibiotic-resistant bacteria (ARB) are pressing public health problems worldwide, and aquatic ecosystems are a recognized reservoir for ARB. We used culture-dependent methods and quantitative molecular techniques to detect and quantify ARB and antibiotic resistance genes (ARGs) in source waters, drinking water treatment plants, and tap water from several cities in Michigan and Ohio. We found ARGs and heterotrophic ARB in all finished water and tap water tested, although the amounts were small. The quantities of most ARGs were greater in tap water than in finished water and source water. In general, the levels of bacteria were higher in source water than in tap water, and the levels of ARB were higher in tap water than in finished water, indicating that there was regrowth of bacteria in drinking water distribution systems. Elevated resistance to some antibiotics was observed during water treatment and in tap water. Water treatment might increase the antibiotic resistance of surviving bacteria, and water distribution systems may serve as an important reservoir for the spread of antibiotic resistance to opportunistic pathogens.

Antibiotic resistance in the absence of antimicrobial use: mechanisms and implications

The selective pressure generated by the use of antibiotics in clinical, veterinary, husbandry and agricultural practices is considered the major factor responsible for the emergence and spread of antibiotic-resistant bacteria since the beginning of the antibiotic era. However, recent studies have consistently demonstrated that acquired resistance traits can also be found in bacteria isolated from humans and wild animals not subjected to significant antibiotic exposure and living in remote areas of the planet. The scope of this article is to review and discuss the current knowledge on this intriguing phenomenon, which underscores the complexity of the mechanisms involved in the emergence and spread of antibiotic resistance and bears some relevant implications to the design and success of resistance-control strategies.

Nitrofurantoin resistance mechanism and fitness cost in Escherichia coli

The biological fitness cost of antibiotic resistance is a key parameter in determining the rate of appearance and spread of antibiotic-resistant bacteria. We identified mutations conferring nitrofurantoin resistance and examined their effect on the fitness of clinical Escherichia coli isolates. By plating bacterial cells on agar plates containing nitrofurantoin, spontaneous nitrofurantoin-resistant E. coli mutants were isolated. The fitness of susceptible and resistant strains was measured as growth rate in the presence and absence of nitrofurantoin in rich culture medium. Time-kill kinetics of the resistant mutants was compared with the susceptible strains. Resistance mutations were identified by DNA sequencing. Spontaneous resistant mutants of initially susceptible clinical E. coli appeared with a rate of 10(-7)/cell/generation, and these mutants showed a reduction in the growth rate compared with the susceptible parent strain. Similarly, comparison of a set of susceptible and resistant clinical isolates of E. coli showed that the average growth rate of the resistant mutants was approximately 6% lower than the susceptible strains. Furthermore, the bacterial growth rate in the presence of nitrofurantoin at therapeutic levels was greatly reduced even for nitrofurantoin-resistant mutants. The resistance-conferring mutations were identified in the nsfA and nfsB genes that encode oxygen-insensitive nitroreductases. Nitrofurantoin resistance confers a reduction in fitness in E. coli in the absence of antibiotic. In the presence of therapeutic levels of nitrofurantoin, even resistant mutants are so disturbed in growth that they are probably unable to become enriched and establish an infection.

Modeling antibiotic resistance in hospitals: The impact of minimizing treatment duration

Infections caused by antibiotic-resistant pathogens are a global public health problem. Numerous individual- and population-level factors contribute to the emergence and spread of these pathogens. An individual-based model (IBM), formulated as a system of stochastically determined events, was developed to describe the complexities of the transmission dynamics of antibiotic-resistant bacteria. To simplify the interpretation and application of the model's conclusions, a corresponding deterministic model was created, which describes the average behavior of the IBM over a large number of simulations. The integration of these two model systems provides a quantitative analysis of the emergence and spread of antibiotic-resistant bacteria, and demonstrates that early initiation of treatment and minimization of its duration mitigates antibiotic resistance epidemics in hospitals.

The Routine Use of Antibiotics to Promote Animal Growth Does Little to Benefit Protein Undernutrition in the Developing World

Some persons argue that the routine addition of antibiotics to animal feed will help alleviate protein undernutrition in developing countries by increasing meat production. In contrast, we estimate that, if all routine antibiotic use in animal feed were ceased, there would be negligible effects in these countries. Poultry and pork production are unlikely to decrease by more than 2%. Average daily protein supply would decrease by no more than 0.1 g per person (or 0.2% of total protein intake). Eliminating the routine use of in-feed antibiotics will improve human and animal health, by reducing the development and spread of antibiotic-resistant bacteria.

Putting copper into action: copper-impregnated products with potent biocidal activities.

Copper ions, either alone or in copper complexes, have been used for centuries to disinfect liquids, solids, and human tissue. Today copper is used as a water purifier, algaecide, fungicide, nematocide, molluscicide, and antibacterial and antifouling agent. Copper also displays potent antiviral activity. We hypothesized that introducing copper into clothing, bedding, and other articles would provide them with biocidal properties. A durable platform technology has been developed that introduces copper into cotton fibers, latex, and other polymeric materials. This study demonstrates the broad-spectrum antimicrobial (antibacterial, antiviral, antifungal) and antimite activities of copper-impregnated fibers and polyester products. This technology enabled the production of antiviral gloves and filters (which deactivate HIV-1 and other viruses), antibacterial self-sterilizing fabrics (which kill antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci), antifungal socks (which alleviate symptoms of athlete's foot), and anti-dust mite mattress covers (which reduce mite-related allergies). These products did not have skin-sensitizing properties, as determined by guine pig maximization and rabbit skin irritation tests. Our study demonstrates the potential use of copper in new applications. These applications address medical issues of the greatest importance, such as viral transmissions; nosocomial, or healthcare-associated, infections; and the spread of antibiotic-resistant bacteria.

Antimicrobial resistance in Campylobacter spp., Escherichia coli and enterococci associated with pigs in Australia.

The major influences on the amplification and spread of antibiotic-resistant bacteria are the therapeutic use of antibiotics in human medicine and their use in livestock for therapy, prophylaxis and growth promotion. The use of veterinary antibiotics has many benefits to the livestock industries ensuring animal health and welfare, but use at subtherapeutic levels also exerts great selective pressure on emergence of resistant bacteria. The possible effect on human health is a problem of current debate. This study involved sampling pig carcasses, pig meat and assessing the level of resistance in zoonotic enteric bacteria of concern to human health. In South Australian pigs, thermophilic Campylobacter species showed widespread resistance (60-100%) to tylosin, erythromycin, lincomycin, ampicillin and tetracycline. No resistance was seen to ciprofloxacin. The enterococci demonstrated little resistance (0-30%) to vancomycin or virginiamycin, but the overall results from the antibiotic sensitivity testing of the enterococci have demonstrated how widespread their resistance has become. Escherichia coli strains showed widespread resistance to tetracycline and moderately common resistance (30-60%) to ampicillin and sulphadiazine. Resistance to more than one antibiotic was common. Pigs from New South Wales were also sampled and differences in resistance patterns were noted, perhaps reflecting different antibiotic use regimens in that state.