Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study. Lancet Infect Dis. 2010;10:597-602. [PMID: 20705517 PMCID: PMC2933358 DOI: 10.1016/s1473-3099(10)70143-2]

Identification of New Delhi metallo-β-lactamase gene (NDM-1) from a clinical isolate of Acinetobacter junii in China

New Delhi metallo-β-lactamase-1 (NDM-1) is a novel type of metallo-β-lactamase (MBL) responsible for bacterial resistance to β-lactam antibiotics. Acinetobacter junii was previously shown to possess a MBL phenotype; however, the genes responsible for this phenotype were not identified. In this study, we reported the identification of NDM-1 gene in a clinical isolate of A. junii from a child patient in China, which was resistant to all β-lactams except aztreonam but sensitive to aminoglycosides and quinolones. The cloned NDM-1 gene contained an open reading frame of 813 bp and had a nucleotide sequence 99.9% identical (812/813) to reported NDM-1 genes carried by Acinetobacter baumannii , Enterococcus faecium , Escherichia coli , and Klebsiella pneumoniae . Recombinant NDM-1 protein was successfully expressed in E. coli BL21, and antibiotic sensitivities of the NDM-1-producing E. coli were largely similar to the A. junii 1454 isolate. The findings of this study raise attention to the emergence and spread of NDM-1-carrying bacteria in China.

Antibiotics in phase II and III clinical trials

There are 19 compounds in late-stage clinical trials, of which ten may be suitable for Gram-positive infections. However, there are only five compounds in development for Gram-negative infections, in addition to four broad-spectrum ones. There are two new classes in late-stage clinical development. This chapter discusses in some detail each of the antibiotics in Phase II and Phase III clinical trials. Only those that appear in the literature are covered. The shortage of compounds in development for Gram-negatives and the small number of new classes in the pipeline is of serious concern; this matter needs to be addressed by governments, the regulatory authorities, the pharmaceutical industry and academia urgently.

Dissemination of the Klebsiella pneumoniae carbapenemase in the health care settings: tracking the trails of an elusive offender

Transmission of antibiotic resistance genes may be mediated by a variety of molecular mechanisms, from mobility of small genetic elements to clonal spread. Since 1997, the carbapenem-hydrolyzing enzyme Klebsiella pneumoniae carbapenemase (KPC) has spread in the United States and across the world, mainly via a single K. pneumoniae clone, sequence type 258. By tracking the trail of dissemination of the bla_KPC gene inside their institution, Mathers et al. (mBio 2:e00204–11, 2011) have shown evidence of the ability of this gene to spread by several modes, including plasmid transfer and clonal spread. The ever-evolving modes of transmission of resistance genes challenge our ability to detect, track, and eventually control the spread of what has become a major threat to hospitalized patients worldwide.

Appraising contemporary strategies to combat multidrug resistant gram-negative bacterial infections--proceedings and data from the Gram-Negative Resistance Summit

The emerging problem of antibiotic resistance, especially among Gram-negative bacteria (GNB), has become a serious threat to global public health. Very few new antibacterial classes with activity against antibiotic-resistant GNB have been brought to market. Renewed and growing attention to the development of novel compounds targeting antibiotic-resistant GNB, as well as a better understanding of strategies aimed at preventing the spread of resistant bacterial strains and preserving the efficacy of existing antibiotic agents, has occurred. The Gram-Negative Resistance Summit convened national opinion leaders for the purpose of analyzing current literature, epidemiologic trends, clinical trial data, therapeutic options, and treatment guidelines related to the management of antibiotic-resistant GNB infections. After an in-depth analysis, the Summit investigators were surveyed with regard to 4 clinical practice statements. The results then were compared with the same survey completed by 138 infectious disease and critical care physicians and are the basis of this article.

Tn125-related acquisition of blaNDM-like genes in Acinetobacter baumannii

A multidrug-resistant Acinetobacter baumannii isolate recovered from a patient hospitalized in Switzerland after a transfer from Serbia produced the NDM-1 carbapenemase. The bla(NDM-1) gene was part of a chromosomally located Tn125 composite transposon bracketed by two copies of the same insertion sequence, ISAba125. This transposon was also associated with the acquisition and expression of the bla(NDM-2) gene in an A. baumannii isolate in Germany. Tn125 appears to be the main vehicle for dissemination of bla(NDM) genes in that species.

Modified Hodge test: A simple and effective test for detection of carbapenemase production

BACKGROUND AND OBJECTIVES

Resistance among bacterial isolates is the leading cause of increased mortality and morbidity worldwide. Carbapenems once thought to be effective are becoming ineffective mostly due to the emergence of carbapenemase. This study was designed to determine in vitro efficacy of Modified Hodge test for detection of carbapenemase production in Gram negative rods.

MATERIAL AND METHODS

The study was done in the Department of Microbiology, Armed Forces Institute of Pathology Rawalpindi Pakistan from January 2010 to December 2010. A total of 200 Gram negative rods from different clinical samples were taken. Those isolates which showed intermediate or susceptible zones i.e 16mm-21mm on disc diffusion were included in the study. These isolates were then subjected to Modified Hodge test.

RESULT

Out of 200 isolates, 138 (69%) were positive for carbapenemase production by Modified Hodge test. Out of 138 MHT positive organisms, the frequency of E. coli was 38%, followed by Pseudomonas aeruginosa (30%), Klebsiella pneumoniae (17%), Acinetobacter baumannii (12%), Citrobacter diversus (2%) and Enterobacter agglomerans (1.4%).

CONCLUSION

Modified Hodge test is a simple test which can be performed in the routine lab for detection of carbapenemases in isolates showing intermediate or sensitive zone diameter on disc diffusion.

Scenario driven data modelling: a method for integrating diverse sources of data and data streams

Background

Biology is rapidly becoming a data intensive, data-driven science. It is essential that data is represented and connected in ways that best represent its full conceptual content and allows both automated integration and data driven decision-making. Recent advancements in distributed multi-relational directed graphs, implemented in the form of the Semantic Web make it possible to deal with complicated heterogeneous data in new and interesting ways.

Results

This paper presents a new approach, scenario driven data modelling (SDDM), that integrates multi-relational directed graphs with data streams. SDDM can be applied to virtually any data integration challenge with widely divergent types of data and data streams. In this work, we explored integrating genetics data with reports from traditional media. SDDM was applied to the New Delhi metallo-beta-lactamase gene (NDM-1), an emerging global health threat. The SDDM process constructed a scenario, created a RDF multi-relational directed graph that linked diverse types of data to the Semantic Web, implemented RDF conversion tools (RDFizers) to bring content into the Sematic Web, identified data streams and analytical routines to analyse those streams, and identified user requirements and graph traversals to meet end-user requirements.

Conclusions

We provided an example where SDDM was applied to a complex data integration challenge. The process created a model of the emerging NDM-1 health threat, identified and filled gaps in that model, and constructed reliable software that monitored data streams based on the scenario derived multi-relational directed graph. The SDDM process significantly reduced the software requirements phase by letting the scenario and resulting multi-relational directed graph define what is possible and then set the scope of the user requirements. Approaches like SDDM will be critical to the future of data intensive, data-driven science because they automate the process of converting massive data streams into usable knowledge.

The crisis of no new antibiotics--what is the way forward?

Antibiotic use not only underpins modern medicine, but has brought huge changes to the world, especially in expectations of survival of children into adulthood. The theme of World Health Day, 2011, was "antimicrobial resistance: no action today and no cure tomorrow". The demise of antibacterial drug discovery brings the spectre of untreatable infections. To prevent this crisis immediate action is needed and a new initiative, Antibiotic Action, has been launched. By bringing together communities who need these drugs with academia, health-care professionals, and pharmaceutical companies, this initiative aims to strengthen and enhance academic-industrial partnerships, bring about revision of costly and laborious processes of licensing and regulation of new antibiotics, and address the economics of antimicrobial drugs (cost of use vs profit). A global alliance for antibiotic drug discovery and development would provide a platform for these initiatives.

Rapid detection of blaIMP-6 by amplification refractory mutation system

Klebsiella pneumoniae resistant to almost all ß-lactams except imipenem designated as ISMRK (imipenem-susceptible meropenem-resistant Klebsiella) is emerging in Japan. All ISMRK carries bla(IMP-6) which differs from bla(IMP-1) by only a single nucleotide at position 640. We devised a rapid detection system of bla(IMP-6) by using ARMS PCR.

The role of long-range intermolecular interactions in discovery of new drugs

INTRODUCTION

Long-range intermolecular interactions (interactions at distances between 100 and 1000 Å) play an important role in the interaction between drugs and therapeutic targets, and design techniques based on this concept could significantly improve and accelerate new drug discovery. Understanding these long-range intermolecular interactions will also help further our understanding of the molecular mechanisms and the underlying basic biological processes.

AREAS COVERED

This article looks at the physical bases of long-range intermolecular interactions in biological systems with a brief review of the literature data to support this concept. The article also gives some examples of techniques used in drug discovery that were based on the long-range intermolecular interaction concept.

EXPERT OPINION

The electron-ion interaction potential (EIIP) and average quasivalence number (AQVN) concepts shed new light on the role of long-range intermolecular interactions in biological systems. Further research of physicochemical mechanisms underlying long-range interactions between biological molecules is necessary for a better understanding of the basic biological processes. The addition of the computer-aided design techniques based on the EIIP/AQVN concept to the research and development will lead not only to a significant reduction in cost but also to an acceleration in the development of new drugs.

When and how to cover for resistant gram-negative bacilli in severe sepsis and septic shock

In the 80s and 90s, increasing antibiotic resistance was met by the introduction of new effective agents with broader antibacterial spectra for the empirical treatment of severe infections. In recent years, however, few novel antimicrobials have been developed, and this has critically weakened our strength in the fight against resistant bacteria, especially Gram-negative bacilli. It has been well proven that mortality increases if initial empirical antibiotic treatment for severe infection is inappropriate due to resistance of the pathogen. Physicians are already faced with the increasing challenge of untreatable or almost untreatable Gram-negative infections due to antibiotic resistance. Empirical treatment with broader spectra and high antibiotic pressure both in- and outside hospital is the driving force behind resistance. Since new efficient drugs against Gram-negative bacilli will not be available for some time, the best we can do to stop infections caused by multidrug-resistant bacteria is to improve infection control and choice of antibiotics, which should be based on surveillance of local antibiotic consumption and resistance. We must learn more about the revived antibacterial agents colistin and fosfomycin, and the few next generation Gram-negative antibiotics that have been developed. The aim of this review is to give an update on present therapeutic options in the fight against multidrug-resistant Gram-negative bacteria.

A call to arms: the imperative for antimicrobial stewardship

Antimicrobial resistance is a major public health crisis. The prevalence of drug-resistant organisms, such as the emerging NAP1 strain of Clostridium difficile, now highly resistant to fluoroquinolones, Acinetobacter species, Klebsiella pneumoniae carbapenemase-producing organisms, and methicillin-resistant Staphylococcus aureus, is increasing nationwide. The sources of antimicrobial resistance are manifold, but there is a well-documented causal relationship between antimicrobial use and misuse and the emergence of antimicrobial-resistant pathogens. As the development of new antimicrobial agents is on the decline, the medical community, across all specialties and in conjunction with public health services, must develop and implement programs and strategies designed to preserve the integrity and effectiveness of the existing antimicrobial armamentarium. Such strategies are collectively known as antimicrobial stewardship programs and have the potential to minimize the emergence of resistant pathogens.

The emerging NDM carbapenemases

Carbapenems were the last β-lactams retaining near-universal anti-Gram-negative activity, but carbapenemases are spreading, conferring resistance. New Delhi metallo-β-lactamase (NDM) enzymes are the latest carbapenemases to be recognized and since 2008 have been reported worldwide, mostly in bacteria from patients epidemiologically linked to the Indian subcontinent, where they occur widely in hospital and community infections, and also in contaminated urban water. The main type is NDM-1, but minor variants occur. NDM enzymes are present largely in Enterobacteriaceae, but also in non-fermenters and Vibrionaceae. Dissemination predominantly involves transfer of the blaNDM-1 gene among promiscuous plasmids and clonal outbreaks. Bacteria with NDM-1 are typically resistant to nearly all antibiotics, and reliable detection and surveillance are crucial.

Antibiotic stewardship: overcoming implementation barriers

PURPOSE OF REVIEW

Antimicrobial stewardship is now recognized as a formal strategy for curbing the upward trend in antibiotic resistance. Literature on antimicrobial stewardship has focused on areas of strategic importance and operational delivery. A number of barriers have been recognized in the implementation of successful programs. These include lack of physician participation, lack of diagnostic facility, absence of formal mechanism of data collection, variation between countries, and lack of cooperative strategies. In this review, we suggest strategies to overcome these barriers.

RECENT FINDINGS

In the last few years, it has been recognized that an executive program is necessary for successful implementation of strategies to control the growing antibiotic resistance. Efforts have been made at higher levels of government through organizations such as the European Centre for Disease Prevention and Control. The need for community healthcare involvement has also been recognized. At a local level, strategies to promote cooperation between various committees (e.g. infection control and antimicrobial management teams) have been proposed and adopting antibiotic care bundles as part of patient safety and healthcare is being explored.

SUMMARY

We suggest that executive level planning, local cooperation, sustained education, emphasis on de-escalation, and use of care bundles could stem the tide of growing resistance.

β-Lactam/β-lactam inhibitor combinations for the treatment of bacteremia due to extended-spectrum β-lactamase-producing Escherichia coli: a post hoc analysis of prospective cohorts

BACKGROUND

Extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) is an important cause of invasive infections. Alternatives to carbapenems--considered the drugs of choice--are needed because of the emergence of carbapenemase-producing enterobacteria. The efficacy of ß-lactam/ß-lactam inhibitors (BLBLI) in such infections is controversial.

METHODS

The authors performed a post hoc analysis of patients with bloodstream infections due to ESBL-EC from 6 published prospective cohorts. Mortality and length of hospital stay in patients treated with an active BLBLI (amoxicillin-clavulanic acid [AMC] and piperacillin-tazobactam [PTZ]) or carbapenem were compared in 2 cohorts: the empirical therapy cohort (ETC) and the definitive therapy cohort (DTC). Confounding was controlled by multivariate analysis; for patients in the ETC, a propensity score for receiving carbapenem was also used.

RESULTS

The ETC included 103 patients (BLBLI, 72; carbapenem, 31), and the DTC included 174 (BLBLI, 54; carbapenem, 120). Mortality rates at day 30 for those treated with BLBLI versus carbapenems were 9.7% versus 19.4% for the ETC and 9.3% versus 16.7% for the DTC, respectively (P > .2, log-rank test). After adjustment for confounders, no association was found between either empirical therapy with BLBLI (adjusted hazard ratio [HR], 1.14; 95% confidence interval [CI], .29-4.40; P = .84) or definitive therapy (adjusted HR, 0.76; 95% CI, .28-2.07; P = .5) and increased mortality. Furthermore, BLBLI therapy, with respect to carbapenem, was not found to influence length of hospital stay.

CONCLUSIONS

These results suggest that AMC and PTZ are suitable alternatives to carbapenems for treating patients with bloodstream infections due to ESBL-EC if active in vitro and would be particularly useful as definitive therapy.

Characterization of Streptomyces padanus JAU4234, a producer of actinomycin X₂, fungichromin, and a new polyene macrolide antibiotic

Strain JAU4234, identified as Streptomyces padanus, was isolated from soil collected in Jiangxi Province, China. It produced actinomycin X2, fungichromin, and a new polyene macrolide compound with antifungal activity, antifungalmycin 702. Antifungalmycin 702 had good general antifungal activity and may have potential future agricultural and/or clinical applications.

Bacterial recombination promotes the evolution of multi-drug-resistance in functionally diverse populations

Bacterial recombination is believed to be a major factor explaining the prevalence of multi-drug-resistance (MDR) among pathogenic bacteria. Despite extensive evidence for exchange of resistance genes from retrospective sequence analyses, experimental evidence for the evolutionary benefits of bacterial recombination is scarce. We compared the evolution of MDR between populations of Acinetobacter baylyi in which we manipulated both the recombination rate and the initial diversity of strains with resistance to single drugs. In populations lacking recombination, the initial presence of multiple strains resistant to different antibiotics inhibits the evolution of MDR. However, in populations with recombination, the inhibitory effect of standing diversity is alleviated and MDR evolves rapidly. Moreover, only the presence of DNA harbouring resistance genes promotes the evolution of resistance, ruling out other proposed benefits for recombination. Together, these results provide direct evidence for the fitness benefits of bacterial recombination and show that this occurs by mitigation of functional interference between genotypes resistant to single antibiotics. Although analogous to previously described mechanisms of clonal interference among alternative beneficial mutations, our results actually highlight a different mechanism by which interactions among co-occurring strains determine the benefits of recombination for bacterial evolution.

Multidrug-resistant Acinetobacter spp.: increasingly problematic nosocomial pathogens

Pathogenic bacteria have increasingly been resisting to antimicrobial therapy. Recently, resistance problem has been relatively much worsened in Gram-negative bacilli. Acinetobacter spp. are typical nosocomial pathogens causing infections and high mortality, almost exclusively in compromised hospital patients. Acinetobacter spp. are intrinsically less susceptible to antibiotics than Enterobacteriaceae, and have propensity to acquire resistance. A surveillance study in Korea in 2009 showed that resistance rates of Acinetobacter spp. were very high: to fluoroquinolone 67%, to amikacin 48%, to ceftazidime 66% and to imipenem 51%. Carbapenem resistance was mostly due to OXA type carbapenemase production in A. baumannii isolates, whereas it was due to metallo-β-lactamase production in non-baumannii Acinetobacter isolates. Colistin-resistant isolates were rare but started to be isolated in Korea. Currently, the infection caused by multidrug-resistant A. baumannii is among the most difficult ones to treat. Analysis at tertiary care hospital in 2010 showed that among the 1,085 isolates of Acinetobacter spp., 14.9% and 41.8% were resistant to seven, and to all eight antimicrobial agents tested, respectively. It is known to be difficult to prevent Acinetobacter spp. infection in hospitalized patients, because the organisms are ubiquitous in hospital environment. Efforts to control resistant bacteria in Korea by hospitals, relevant scientific societies and government agencies have only partially been successful. We need concerted multidisciplinary efforts to preserve the efficacy of currently available antimicrobial agents, by following the principles of antimicrobial stewardship.

Ecology drives a global network of gene exchange connecting the human microbiome

Horizontal gene transfer (HGT), the acquisition of genetic material from non-parental lineages, is known to be important in bacterial evolution. In particular, HGT provides rapid access to genetic innovations, allowing traits such as virulence, antibiotic resistance and xenobiotic metabolism to spread through the human microbiome. Recent anecdotal studies providing snapshots of active gene flow on the human body have highlighted the need to determine the frequency of such recent transfers and the forces that govern these events. Here we report the discovery and characterization of a vast, human-associated network of gene exchange, large enough to directly compare the principal forces shaping HGT. We show that this network of 10,770 unique, recently transferred (more than 99% nucleotide identity) genes found in 2,235 full bacterial genomes, is shaped principally by ecology rather than geography or phylogeny, with most gene exchange occurring between isolates from ecologically similar, but geographically separated, environments. For example, we observe 25-fold more HGT between human-associated bacteria than among ecologically diverse non-human isolates (P = 3.0 × 10(-270)). We show that within the human microbiome this ecological architecture continues across multiple spatial scales, functional classes and ecological niches with transfer further enriched among bacteria that inhabit the same body site, have the same oxygen tolerance or have the same ability to cause disease. This structure offers a window into the molecular traits that define ecological niches, insight that we use to uncover sources of antibiotic resistance and identify genes associated with the pathology of meningitis and other diseases.

Carbapenem-resistant Enterobacteriaceae: epidemiology and prevention

Over the past 10 years, dissemination of Klebsiella pneumoniae carbapenemase (KPC) has led to an increase in the prevalence of carbapenem-resistant Enterobacteriaceae (CRE) in the United States. Infections caused by CRE have limited treatment options and have been associated with high mortality rates. In the previous year, other carbapenemase subtypes, including New Delhi metallo-β-lactamase, have been identified among Enterobacteriaceae in the United States. Like KPC, these enzymes are frequently found on mobile genetic elements and have the potential to spread widely. As a result, preventing both CRE transmission and CRE infections have become important public health objectives. This review describes the current epidemiology of CRE in the United States and highlights important prevention strategies.

Country-to-country transfer of patients and the risk of multi-resistant bacterial infection

Management of patients with a history of healthcare contact in multiple countries is now a reality for many clinicians. Leisure tourism, the burgeoning industry of medical tourism, military conflict, natural disasters, and changing patterns of human migration may all contribute to this emerging epidemiological trend. Such individuals may be both vectors and victims of healthcare-associated infection with multiresistant bacteria. Current literature describes intercountry transfer of multiresistant Acinetobacter spp and Klebsiella pneumoniae (including Klebsiella pneumoniae carbapenemase- and New Delhi metallo-β-lactamase-producing strains), methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and hypervirulent Clostridium difficile. Introduction of such organisms to new locations has led to their dissemination within hospitals. Healthcare institutions should have sound infection prevention strategies to mitigate the risk of dissemination of multiresistant organisms from patients who have been admitted to hospitals in other countries. Clinicians may also need to individualize empiric prescribing patterns to reflect the risk of multiresistant organisms in these patients.

The emergence of pan-resistant Gram-negative pathogens merits a rapid global political response

Recent media coverage of New Delhi metallo-β-lactamase (NDM-1) put antibiotic resistance back on the political map if only for the wrong reasons, mainly the reaction to the naming of NDM-1 and the incorrect assumption that medical tourism was being deliberately targeted. However, work on NDM-1 has most certainly highlighted the rapid dissemination of new antibiotic resistance mechanisms via economic globalization. The example of NDM-1 has also magnified the desperate need for a publicly funded global antibiotic surveillance system rather than just national or regional systems. Furthermore, there is a pressing need to establish a global task force to enforce international transparency and accountability on antibiotic stewardship and the implementation of measures to curb antibiotic resistance. An international antibiotic stewardship index should be established that is related to each country's gross domestic product (GDP) and assesses how much of their GDP is committed to publically funded health initiatives aimed at controlling antibiotic resistance.

Plasmid DNA linearization in the antibacterial action of a new fluorescent Ag nanoparticle-paracetamol dimer composite

Herein, we report the generation of a composite comprised of p-hydroxyacetanilide dimer and Ag nanoparticles (NPs) by reaction of AgNO(3) and p-hydroxyacetanilide. The formation of the composite was established by UV-vis, FTIR and NMR spectroscopy, transmission electron microscopy and X-ray diffraction along with substantiation by mass spectrometry. Interestingly, the composite exhibited an emission spectrum with a peak at 435 nm when excited by light of wavelength 320 nm. The composite showed superior antimicrobial activity with respect to its individual components against a wide range of Gram positive and Gram negative bacteria at relatively low concentrations of Ag NPs and at which there was no apparent cytotoxicity against mammalian cells. Our results suggest that the composite strongly interacted with the bacterial cell walls leading to cell bursting. Interestingly, enhancement in the reactive oxygen species (ROS) generation in bacteria was observed in the presence of the composite. It is proposed that the ROS generation led to oxidation of the dimer to N-acetyl-p-benzoquinone imine (NAPQI). The generated NAPQI acted as a DNA gyrase inhibitor causing cell death following linearization of DNA.

Designed antimicrobial and antitumor peptides with high selectivity

We report a new class of cationic amphiphilic peptides with short sequences, G(IIKK)(n)I-NH(2) (n = 1-4), that can kill Gram-positive and Gram-negative bacteria as effectively as several well-known antimicrobial peptides and antibiotics. In addition, some of these peptides possess potent antitumor activities against cancer cell lines. Moreover, their hemolytic activities against human red blood cells (hRBCs) remain remarkably low even at some 10-fold bactericidal minimum inhibitory concentrations (MICs). When bacteria or tumor cells are cocultured with NIH 3T3 fibroblast cells, G(IIKK)(3)I-NH(2) showed fast and strong selectivity against microbial or tumor cells, without any adverse effect on NIH 3T3 cells. The high selectivity and associated features are attributed to two design tactics: the use of Ile residues rather than Leu and the perturbation of the hydrophobic face of the helical structure with the insertion of a positively charged Lys residue. This class of simple peptides hence offers new opportunities in the development of cost-effective and highly selective antimicrobial and antitumor peptide-based treatments.

Plasmid-mediated transfer of the bla(NDM-1) gene in Gram-negative rods

The latest threat of multidrug-resistant Gram-negative bacteria corresponds to the emergence of carbapenemase NDM-1 (New Delhi metallo-β-lactamase) producers, mostly in Enterobacteriacae. Five bla(NDM) (-1) -positive plasmids of different incompatibility groups (IncL/M, FII, A/C and two untypeable plasmids) from clinical Enterobacteriaceae were evaluated for conjugation properties and host specificity. Successful conjugative transfers were obtained using all tested enterobacterial species as recipients (Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium and Proteus mirabilis) and all plasmid types. Conjugation frequencies varied from 1 × 10(-4) to 6 × 10(-8) transconjugants per donor. Higher conjugation rates were obtained for two plasmids at 30 °C compared with that observed at 25 and 37 °C. Carbapenems used as selector did not lead to higher conjugation frequencies. None of the five plasmids was transferable to Acinetobacter baumannii or Pseudomonas aeruginosa by conjugation. This work underlines how efficient the spread of the carbapenemase bla(NDM) (-1) gene could be among Enterobacteriaceae.

Mortality and hospital stay associated with resistant Staphylococcus aureus and Escherichia coli bacteremia: estimating the burden of antibiotic resistance in Europe

BACKGROUND

The relative importance of human diseases is conventionally assessed by cause-specific mortality, morbidity, and economic impact. Current estimates for infections caused by antibiotic-resistant bacteria are not sufficiently supported by quantitative empirical data. This study determined the excess number of deaths, bed-days, and hospital costs associated with blood stream infections (BSIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) and third-generation cephalosporin-resistant Escherichia coli (G3CREC) in 31 countries that participated in the European Antimicrobial Resistance Surveillance System (EARSS).

METHODS AND FINDINGS

The number of BSIs caused by MRSA and G3CREC was extrapolated from EARSS prevalence data and national health care statistics. Prospective cohort studies, carried out in hospitals participating in EARSS in 2007, provided the parameters for estimating the excess 30-d mortality and hospital stay associated with BSIs caused by either MRSA or G3CREC. Hospital expenditure was derived from a publicly available cost model. Trends established by EARSS were used to determine the trajectories for MRSA and G3CREC prevalence until 2015. In 2007, 27,711 episodes of MRSA BSIs were associated with 5,503 excess deaths and 255,683 excess hospital days in the participating countries, whereas 15,183 episodes of G3CREC BSIs were associated with 2,712 excess deaths and 120,065 extra hospital days. The total costs attributable to excess hospital stays for MRSA and G3CREC BSIs were 44.0 and 18.1 million Euros (63.1 and 29.7 million international dollars), respectively. Based on prevailing trends, the number of BSIs caused by G3CREC is likely to rapidly increase, outnumbering the number of MRSA BSIs in the near future.

CONCLUSIONS

Excess mortality associated with BSIs caused by MRSA and G3CREC is significant, and the prolongation of hospital stay imposes a considerable burden on health care systems. A foreseeable shift in the burden of antibiotic resistance from Gram-positive to Gram-negative infections will exacerbate this situation and is reason for concern.

Antibiotic Collateral Damage: Resistance and Antibiotic-Associated Diarrhea

The purpose of this review is to describe dilemmas associated with antibiotic collateral damage and provide clinical pharmacists with information to improve antibiotic utilization. The clinical use of antibiotics has been associated with acquisition and spread of nosocomial pathogens and multidrug-resistant strains, such as extended-spectrum beta-lactamases, AmpC hyper-producers, carbapenemases, and resistant gram-positive organisms. The mobility of plasmid-mediated resistance, such as extended-spectrum beta-lactamases and the more recently isolated Klebsiella pneumoniae carbapenemases, have been well-demonstrated with worldwide distribution across several different species. The challenges surrounding antibiotic-associated diarrhea, particularly Clostridium difficile infection (CDI), continue to evolve with outbreaks of hypervirulent strains linked to the use of less commonly implicated antibiotics. Published literature was searched and reviewed using PubMed. Undesirable attributes related to antibiotic use can have broad consequences in addition to their effect on individual patients. This collateral damage can evolve over time, and prescribers must be aware of current concerns and be diligent in their judicious use of antibiotics.

Antimicrobial fibers: therapeutic possibilities and recent advances

The emergence of multi-drug-resistant bacteria such as methicillin-resistant strains of Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, Pseudomonas aeruginosa, Acinetobacter baumannii and extended-spectrum β-lactamase (carbapenemase)-producing Enterobacteriaceae is becoming a serious threat. New-generation antimicrobial agents need to be developed. This includes the design of novel antimicrobial compounds and drug-delivery systems. This review provides an introduction into different classes of antimicrobial materials. The main focus is on strategies for the introduction of antimicrobial properties in polymer materials. These can be roughly divided into surface modification, inclusion of antimicrobial compounds that can leach from the polymer, and the introduction of polymer-bound moieties that provide the polymer with antimicrobial properties. One of the main challenges in the development of antimicrobial polymers for the use in contact with human tissue is the concomitant demand of non-cytotoxicity. Current research is strongly focused on the latter aspect.

The characteristics of VIM-1-producing Klebsiella pneumoniae from South Africa

A study was designed to characterize a carbapenem-resistant Klebsiella pneumoniae (KPSA01) isolated from a patient in Gauteng, South Africa without recent travel outside South Africa. Molecular characterization was done using isoelectric focusing, polymerase chain reaction and sequencing for bla(VIM), bla(IMP), bla(NDM), bla(CTX-Ms), bla(OXAs), bla(TEMs), and bla(SHV), plasmid-mediated quinolone resistance determinants, multilocus sequencing typing, plasmid replicon typing, and addiction factors. KPSA01 produced VIM-1 and belonged to the newly described sequence type ST569. The plasmid that harboured bla(VIM) typed within the narrow host range IncF replicon group, contained the aadA1 gene cassette, and tested positive for the vagCD and ccdAB addiction systems. This is the first report of VIM-1-producing K. pneumoniae outside Europe. It is important that surveillance studies be undertaken in Africa to determine if VIM-1-producing K. pneumoniae are present in significant numbers.

Complete sequencing of the bla(NDM-1)-positive IncA/C plasmid from Escherichia coli ST38 isolate suggests a possible origin from plant pathogens

The complete sequence of the plasmid pNDM-1_Dok01 carrying New Delhi metallo-β-lactamase (NDM-1) was determined by whole genome shotgun sequencing using Escherichia coli strain NDM-1_Dok01 (multilocus sequence typing type: ST38) and the transconjugant E. coli DH10B. The plasmid is an IncA/C incompatibility type composed of 225 predicted coding sequences in 195.5 kb and partially shares a sequence with bla(CMY-2)-positive IncA/C plasmids such as E. coli AR060302 pAR060302 (166.5 kb) and Salmonella enterica serovar Newport pSN254 (176.4 kb). The bla(NDM-1) gene in pNDM-1_Dok01 is terminally flanked by two IS903 elements that are distinct from those of the other characterized NDM-1 plasmids, suggesting that the bla(NDM-1) gene has been broadly transposed, together with various mobile elements, as a cassette gene. The chaperonin groES and groEL genes were identified in the bla(NDM-1)-related composite transposon, and phylogenetic analysis and guanine-cytosine content (GC) percentage showed similarities to the homologs of plant pathogens such as Pseudoxanthomonas and Xanthomonas spp., implying that plant pathogens are the potential source of the bla(NDM-1) gene. The complete sequence of pNDM-1_Dok01 suggests that the bla(NDM-1) gene was acquired by a novel composite transposon on an extensively disseminated IncA/C plasmid and transferred to the E. coli ST38 isolate.