Hospital-acquired infections: diseases with increasingly limited therapies

Feasibility of using a combination of staphylococcal superantigen-like proteins 3, 7 and 11 in a fusion vaccine for Staphylococcus aureus

Staphylococcus aureus is a significant bacterial pathogen in both community and hospital settings, and the escalation of antimicrobial-resistant strains is of immense global concern. Vaccination is an inviting long-term strategy to curb staphylococcal disease, but identification of an effective vaccine has proved to be challenging. Three well-characterized, ubiquitous, secreted immune evasion factors from the staphylococcal superantigen-like (SSL) protein family were selected for the development of a vaccine. Wild-type SSL3, 7 and 11, which inhibit signaling through Toll-like receptor 2, cleavage of complement component 5 and neutrophil function, respectively, were successfully combined into a stable, active fusion protein (PolySSL7311). Vaccination of mice with an attenuated form of the PolySSL7311 protein stimulated significantly elevated specific immunoglobulin G and splenocyte proliferation responses to each component relative to adjuvant-only controls. Vaccination with PolySSL7311, but not a mixture of the individual proteins, led to a > 102 reduction in S. aureus tissue burden compared with controls after peritoneal challenge. Comparable antibody responses were elicited after coadministration of the vaccine in either AddaVax (an analog of MF59) or an Alum-based adjuvant; but only AddaVax conferred a significant reduction in bacterial load, aligning with other studies that suggest both cellular and humoral immune responses are necessary for protective immunity to S. aureus. Anti-sera from mice immunized with PolySSL7311, but not individual proteins, partially neutralized the functional activities of SSL7. This study confirms the importance of these SSLs for the survival of S. aureus in vivo and suggests that PolySSL7311 is a promising vaccine candidate.

Effect of Early Enteral Nutrition on Graft Loss After Living Donor Liver Transplantation: A Propensity Score Matching Analysis

BACKGROUND

This study aimed to elucidate the effect of early enteral nutrition on graft loss within 12 h after living-donor liver transplantation (LDLT) using propensity score-matching analysis and subsequently examine the risk factors for graft loss after LDLT.

METHODS

We retrospectively reviewed the data of 467 LDLT patients who were assigned to the early and non-early groups based on the optimal cutoff value of 12 h for the starting time of early enteral nutrition after LDLT to predict graft loss.

RESULTS

The 1-year graft survival rate of the early group before propensity score-matching was 92.1%, whereas the 1-year graft survival rate of the non-early group was 86.2%. There was no significant difference between the 2 groups (P = .067). The incidences of early allograft dysfunction (EAD), small-for-size graft (SFSG) syndrome, acute cellular rejection (ACR), and sepsis were not statistically different between the 2 groups (P = .12, .91, .46, and .056, respectively). After propensity score-matching, the 1-year graft survival rate of the early group was 94.4%, whereas the 1-year graft survival rate of the non-early group was 85.4% (P = .034). The incidences of EAD, SFSG syndrome, and ACR were not statistically different between the 2 groups (P = .43, .81, and .24, respectively). However, the incidence of sepsis was statistically different between the 2 groups (non-early: 10.7% vs early: 3.6%, P = .038).

CONCLUSION

Early enteral nutrition within 12 h after LDLT may contribute to better graft survival in LDLT patients by preventing sepsis.

Nasogastric enteral feeding tubes modulate preterm colonization in early life

BACKGROUND

Preterm infants are generally fed through nasogastric enteral feeding tubes (NEFTs). The aim of this work was to evaluate the role of NEFTs in the initial colonization of the preterm gut and its evolution within the first 2 weeks after birth.

METHODS

For this purpose, fecal and NEFT-derived samples from 30 preterm infants hospitalized in a neonatal intensive care unit (NICU) were collected from birth to the second week of life. Samples were cultivated in ten culture media, including three for the isolation of antibiotic-resistant microorganisms.

RESULTS

Isolates (561) were identified by 16S ribosomal RNA gene sequencing. Although the first NEFTs inserted into the neonates after birth were rarely colonized, analysis of NEFTs and fecal samples over time revealed a significant increase in bacterial abundance, diversity, and detection frequency. Results showed a parallel colonization between time-matched NEFTs and fecal samples, suggesting an ongoing bidirectional transfer of bacteria from the neonatal gut to the NEFTs and vice versa.

CONCLUSIONS

In short-term hospitalization, length is by far the determinant factor for the early colonization of preterm infants. As NEFT populations reflect the bacterial populations that are colonizing the preterm in a precise moment, their knowledge could be useful to prevent the dissemination of antibiotic-resistant strains.

IMPACT

The hospital environment modulates preterm colonization immediately after birth. The colonization of preterm feces and NEFTs occurs in parallel. There is an ongoing bidirectional transfer of microorganisms from the neonatal gut to the NEFTs and vice versa. Bacterial communities inside NEFTs could act as reservoirs of antibiotic resistance genes. NEFT populations reflect the bacteria that are colonizing the preterm at a precise moment.

Antibiotic resistance in agriculture: Perspectives on upcoming strategies to overcome upsurge in resistance

Antibiotic resistance is a massive problem rising constantly and spreading rapidly since the past decade. The major underlying mechanism responsible for this problem is an overuse or severe misuse of antibiotics. Regardless of this emerging global threat, antibiotics are still being widely used, not only for treatment of human infections, but also to a great extent in agriculture, livestock and animal husbandry. If the current scenario persists, we might enter into a post-antibiotic era where drugs might not be able to treat even the simplest of infections. This review discusses the current status of antibiotic utilization and molecular basis of antibiotic resistance mechanisms acquired by bacteria, along with the modes of transmittance of the resultant resistant genes into human pathogens through their cycling among different ecosystems. The main focus of the article is to provide an insight into the different molecular and other strategies currently being studied worldwide for their use as an alternate to antibiotics with an overall aim to overcome or minimize the global problem of antibiotic resistance.

A facile method for vancomycin C-terminus functionalization and derivatization through hydrazide

Over 60-year clinical use of vancomycin led to the emergence of vancomycin-resistant bacteria and threatened our health. To combat vancomycin-resistant strains, numerous vancomycin analogues were developed, such as Telavancin, Oritavancin and Dalbavancin. Extra structures embedded on C-terminus has been proved to be an effective strategy to promote antibacterial activity of vancomycin against vancomycin-resistant strains. Here, we reported a facile strategy, inspired by native chemical ligation, for vancomycin C-terminus functionalization and derivatization. The introduction of C-terminal hydrazide on vancomycin not only provided us an accessible method for C-terminus functionalization through carbonyl azide and thioester, also acted as an efficient site for vancomycin structure modifications. Based on hydrazide-vancomycin, we effectively conjugated cysteine and cysteine containing peptides onto vancomycin C-terminus, and two fluorescent FITC-vancomycin were prepared through Cys-Maleimide conjugation. Meanwhile, we introduced lipophilic structures onto vancomycin C-terminus via the hydrazide moiety. The obtained vancomycin derivatives were evaluated against both Gram-positive and negative bacteria strains.

Antimicrobial Hyperbranched Polymer-Usnic Acid Complexes through a Combined ROP-RAFT Strategy

Polymer-drug conjugates have received considerable attention over the last decades due to their potential for improving the clinical outcomes for a range of diseases. It is of importance to develop methods for their preparation that have simple synthesis and purification requirements but maintain high therapeutic efficacy and utilize macromolecules that can be cleared via natural excretory pathways upon breakdown. Herein, the combination of ring-opening polymerization (ROP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization is described for the straightforward synthesis of amphiphilic, stimuli-responsive, biodegradable, and highly functionalizable hyperbranched polymers. These unimolecular nanoparticles demonstrate a versatile platform for the synthesis of polymer-drug conjugates owing to the inclusion of a Boc-protected polycarbonate moiety in either a block or random copolymer formation. A proof-of-concept study on the complexation of the poorly water-soluble antimicrobial drug usnic acid results in polymer-drug complexes with powerful antimicrobial properties against gram-positive bacteria. Therefore, this work highlights the potential of amphiphilic and biodegradable hyperbranched polymers for antimicrobial applications.

Continuous Peritoneal Dialysis-Associated Peritonitis of Nosocomial Origin

Objective

To describe our experience with nosocomial continuous peritoneal dialysis (CPD)-associated peritonitis focusing on the incidence, possible risk factors, spectrum of organisms, and outcome.

Design

Retrospective review of the medical records of our CPD patients admitted to an acute-care hospital between November, 1993 and December, 1994.

Setting

University-associated acute-care hospitals in New Haven, Connecticut.

Patients

One hundred and eighty-eight patients maintained on CPD therapy and admitted to an acute-care hospital.

Results

Nineteen patients (5%) developing nosocomial peritonitis (NP) were identified from the 408 admissions occurring during the study period. Patients developing NP were older than the hospitalized CPD patients not developing NP(65.5± 14.6vs58.4± 14.7years, p<0.05). Comorbid diseases including diabetes, peripheral vascular disease, gastrointestinal disease, cardiovascular disease, and human immunodeficiency virus seropositivity were not more common in the patients developing NP. Patients developing NP were hospitalized significantly longer than the CPD patients not developing NP (39.5 ± 46.5 days vs 12.7 ± 12.4 days, p < 0.001). The mean serum albumin was lower in the NP patients than in the CPD patients not developing NP (2.35 ± 0.52 g/dL vs 3.02 ± 0.60 g/dL, p < 0.001). Antecedent antibiotic use and performance of invasive procedures were noted in 89% and 68% of the patients developing NP, respectively. Staphylococcal species, enterococcal species, and gram-negative organisms accounted for 26%, 21 %, and 53% of the episodes of NP, respectively. Furthermore, two strains of Enterococcus resistant to vancomycin were cultured. Eight patients developing NP expired, 8 patients continued CPD therapy, 2 patients transferred to hemodialysis, and one patient recovered renal function.

Conclusion

We conclude that NP is uncommon. Increased age, increased length of hospital stay, and hypoalbuminemia may predispose patients to the development of NP. Further studies with case controls should help to clarify whether antecedent antibiotics or prior performance of invasive procedures predispose patients to the development of nosocomial peritonitis. The spectrum of organisms accounting for NP is different than the spectrum of organisms causing community-acquired CPD-associated peritonitis. Some of these organisms may be resistant to standard antibiotic therapies. Patients developing NP do poorly, with 42% expiring while being treated for NP.

Surface Characterization, Antimicrobial Effectiveness, and Human Cell Response for a Biomedical Grade Polyurethane Blended with a Mixed Soft Block PTMO-Quat/PEG Copolyoxetane Polyurethane

Infection is a serious medical complication associated with health care environments. Despite advances, the 5-10% incidence of infections for hospital patients is well documented. Sources of pathogenic organisms include medical devices such as catheters and endotracheal tubes. Offering guidance for curbing the spread of such infections, a model antimicrobial coating is described herein that kills bacteria on contact but is compatible with human cells. To achieve these characteristics, a novel blend of a conventional biomedical grade polyurethane (Tecoflex) with mixed soft block polyurethane is described. The functional polyurethane (UP-C12-50-T) has a copolyoxetane soft block P-C12-50 with quaternary ammonium (C12) and PEG-like side chains and a conventional poly(tetramethylene oxide) (PTMO, T) soft block. DSC and DMA data point to limited miscibility of UP-C12-50-T with Tecoflex. The blend of Tecoflex with 10 wt % UP-C12-50-T designated UP-C12-50-T-10 radically changed surface properties. Evidence for surface concentration of the P-C12-50 soft block was obtained by atomic force microscopy (AFM), dynamic contact angles (DCAs), zeta potentials (ζ), and X-ray photoelectron spectroscopy (XPS). The antimicrobial effectiveness of the blend coatings was established by the ASTM E2149 "shake flask" test for challenges of E. coli and a methicillin resistant strain of S. epidermidis. Cytocompatibility was demonstrated with an in vitro test designed for direct contact (ISO 10993-5). Growth of human mesenchymal stem cells (MSCs) beside and under UP-C12-50-T-10 indicated remarkable biocompatibility for a composition that is also strongly antimicrobial. Overall, the results point to a model coating with a level of P-C12-50 that combines high antimicrobial effectiveness and low toxicity to human cells.

Avilamycin and evernimicin induce structural changes in rProteins uL16 and CTC that enhance the inhibition of A-site tRNA binding

Two structurally unique ribosomal antibiotics belonging to the orthosomycin family, avilamycin and evernimicin, possess activity against Enterococci, Staphylococci, and Streptococci, and other Gram-positive bacteria. Here, we describe the high-resolution crystal structures of the eubacterial large ribosomal subunit in complex with them. Their extended binding sites span the A-tRNA entrance corridor, thus inhibiting protein biosynthesis by blocking the binding site of the A-tRNA elbow, a mechanism not shared with other known antibiotics. Along with using the ribosomal components that bind and discriminate the A-tRNA-namely, ribosomal RNA (rRNA) helices H89, H91, and ribosomal proteins (rProtein) uL16-these structures revealed novel interactions with domain 2 of the CTC protein, a feature typical to various Gram-positive bacteria. Furthermore, analysis of these structures explained how single nucleotide mutations and methylations in helices H89 and H91 confer resistance to orthosomycins and revealed the sequence variations in 23S rRNA nucleotides alongside the difference in the lengths of the eukaryotic and prokaryotic α1 helix of protein uL16 that play a key role in the selectivity of those drugs. The accurate interpretation of the crystal structures that could be performed beyond that recently reported in cryo-EM models provide structural insights that may be useful for the design of novel pathogen-specific antibiotics, and for improving the potency of orthosomycins. Because both drugs are extensively metabolized in vivo, their environmental toxicity is very low, thus placing them at the frontline of drugs with reduced ecological hazards.

Modeling economic implications of alternative treatment strategies for acute bacterial skin and skin structure infections

OBJECTIVE

The economic implications from the US Medicare perspective of adopting alternative treatment strategies for acute bacterial skin and skin structure infections (ABSSSIs) are substantial. The objective of this study is to describe a modeling framework that explores the impact of decisions related to both the location of care and switching to different antibiotics at discharge.

METHODS

A discrete event simulation (DES) was developed to model the treatment pathway of each patient through various locations (emergency department [ED], inpatient, and outpatient) and the treatments prescribed (empiric antibiotic, switching to a different antibiotic at discharge, or a second antibiotic). Costs are reported in 2012 USD.

RESULTS

The mean number of days on antibiotic in a cohort assigned to a full course of vancomycin was 11.2 days, with 64% of the treatment course being administered in the outpatient setting. Mean total costs per patient were $8671, with inpatient care accounting for 58% of the costs accrued. The majority of outpatient costs were associated with parenteral administration rather than drug acquisition or monitoring. Scenarios modifying the treatment pathway to increase the proportion of patients receiving the first dose in the ED, and then managing them in the outpatient setting or prescribing an oral antibiotic at discharge to avoid the cost associated with administering parenteral therapy, therefore have a major impact and lower the typical cost per patient by 11-20%. Since vancomycin is commonly used as empiric therapy in clinical practice, based on these analyses, a shift in treatment practice could result in substantial savings from the Medicare perspective.

CONCLUSIONS

The choice of antibiotic and location of care influence the costs and resource use associated with the management of ABSSSIs. The DES framework presented here can provide insight into the potential economic implications of decisions that modify the treatment pathway.

Efficacy of the small molecule inhibitor of Lipid II BAS00127538 against Acinetobacter baumannii

Objective

To test the activity of a small molecule compound that targets Lipid II against Acinetobacter baumannii.

Methods

Susceptibility to small molecule Lipid II inhibitor BAS00127538 was assessed using carbapenem- and colistin-resistant clinical isolates of A. baumannii. In addition, synergy between colisitin and this compound was assessed.

Results

Small molecule Lipid II inhibitor BAS00127538 potently acts against A. baumannii and acts synergistically with colistin.

Conclusion

For the first time, a compound that targets Lipid II is described that acts against multi-drug resistant isolates of A. baumannii. The synergy with colistin warrants further lead development of BAS00127538.

A modern-day purgatory: older adults in the emergency department with nonoperative injuries

Older adults frequently present to the emergency department (ED) with injuries that do not require operative treatment but are sufficiently severe to make it unsafe for them to return home. These individuals typically do not meet criteria for hospital admission, but because of limited reimbursement for observation, admitting physicians are often reluctant to accept these individuals for observation. Admission to a skilled nursing or assisted living facility from the ED or rapid access to additional in-home care is also often difficult or impossible. As a result, older adults with nonoperative injuries often spend a long time in the ED waiting for an appropriate disposition. The challenges of identifying an appropriate disposition for these individuals, the consequences for patients, and some potential solutions to this commonly encountered problem are described.

Turning defense into offense: defensin mimetics as novel antibiotics targeting lipid II

We have previously reported on the functional interaction of Lipid II with human alpha-defensins, a class of antimicrobial peptides. Lipid II is an essential precursor for bacterial cell wall biosynthesis and an ideal and validated target for natural antibiotic compounds. Using a combination of structural, functional and in silico analyses, we present here the molecular basis for defensin-Lipid II binding. Based on the complex of Lipid II with Human Neutrophil peptide-1, we could identify and characterize chemically diverse low-molecular weight compounds that mimic the interactions between HNP-1 and Lipid II. Lead compound BAS00127538 was further characterized structurally and functionally; it specifically interacts with the N-acetyl muramic acid moiety and isoprenyl tail of Lipid II, targets cell wall synthesis and was protective in an in vivo model for sepsis. For the first time, we have identified and characterized low molecular weight synthetic compounds that target Lipid II with high specificity and affinity. Optimization of these compounds may allow for their development as novel, next generation therapeutic agents for the treatment of Gram-positive pathogenic infections.

Every year, an increasing number of people are at risk for bacterial infections that cannot be effectively treated. This is because many bacteria are becoming more resistant to antibiotics. Of particular concern is the rise in hospital-acquired infections. Infection caused by the methicillin-resistant Staphylococcus aureus bacterium or MRSA is the cause of many fatalities and puts a burden on health care systems in many countries. The antibiotic of choice for treatment of S. aureus infections is vancomycin, an antimicrobial peptide that kills bacteria by binding to the bacterial cell wall component Lipid II. Here, we have identified for the first time, small synthetic compounds that also bind Lipid II with the aim to develop new antibiotic drugs to fight against bacterial infections.

Rapid single cell detection of Staphylococcus aureus by aptamer-conjugated gold nanoparticles

Staphylococcus aureus is one of the most important human pathogens, causing more than 500,000 infections in the United States each year. Traditional methods for bacterial culture and identification take several days, wasting precious time for patients who are suffering severe bacterial infections. Numerous nucleic acid-based detection methods have been introduced to address this deficiency; however, the costs and requirement for expensive equipment may limit the widespread use of such technologies. Thus, there is an unmet demand of new platform technology to improve the bacterial detection and identification in clinical practice. In this study, we developed a rapid, ultra-sensitive, low cost, and non-polymerase chain reaction (PCR)-based method for bacterial identification. Using this method, which measures the resonance light-scattering signal of aptamer-conjugated gold nanoparticles, we successfully detected single S. aureus cell within 1.5 hours. This new platform technology may have potential to develop a rapid and sensitive bacterial testing at point-of-care.

Bacterial sepsis after living donor liver transplantation: the impact of early enteral nutrition

BACKGROUND

Bacterial sepsis is a significant problem that must be addressed after living donor liver transplantation (LDLT).

STUDY DESIGN

A retrospective analysis of 346 adult-to-adult LDLT patients was performed.

RESULTS

Forty-six patients (13.3%) experienced bacterial sepsis, with primary and secondary origins in 23.9% and 76.1%, respectively. Gram-negative bacteria accounted for 71.7% of the bacteria isolated. The 2-year cumulative graft survival rate in patients with bacterial sepsis was 45.7%. Patients with bacterial sepsis secondary to pneumonia (n = 12) had poorer 2-year graft survival rates (16.7%) than did those with primary or other types of secondary sepsis (p = 0.004). Multivariate analysis showed that intraoperative massive blood loss >10L (p < 0.001) and no enteral feeding started within 48 hours after transplantation (p = 0.005) were significant risk factors for bacterial sepsis. Among patients who received enteral nutrition, the incidences of bacterial sepsis in patients who received enteral nutrition within 48 hours (n = 135) or later than 48 hours (n = 57) were 5.9% and 21.0%, respectively (p = 0.002). The incidence of early graft loss was 8-fold higher in recipients with massive intraoperative blood loss without early enteral nutrition (p < 0.001).

CONCLUSIONS

Early enteral nutrition was associated with significantly reduced risk of developing bacterial sepsis after LDLT.

Gold-catalyzed cyclizations of alkynol-based compounds: synthesis of natural products and derivatives

The last decade has witnessed dramatic growth in the number of reactions catalyzed by gold complexes because of their powerful soft Lewis acid nature. In particular, the gold-catalyzed activation of propargylic compounds has progressively emerged in recent years. Some of these gold-catalyzed reactions in alkynes have been optimized and show significant utility in organic synthesis. Thus, apart from significant methodology work, in the meantime gold-catalyzed cyclizations in alkynol derivatives have become an efficient tool in total synthesis. However, there is a lack of specific review articles covering the joined importance of both gold salts and alkynol-based compounds for the synthesis of natural products and derivatives. The aim of this Review is to survey the chemistry of alkynol derivatives under gold-catalyzed cyclization conditions and its utility in total synthesis, concentrating on the advances that have been made in the last decade, and in particular in the last quinquennium.

A review of telavancin in the treatment of complicated skin and skin structure infections (cSSSI)

Telavancin is a novel antibiotic being investigated for the treatment of serious infections caused by Gram-positive bacteria, including complicated skin and skin structure infections (cSSSI) and pneumonia. This once-daily intravenous lipoglycopeptide exerts rapid bactericidal activity via a dual mechanism of action. It is intended for use to combat infections caused by Staphylococcus aureus and other Gram-positive bacteria, including methicillin-resistant and vancomycin-intermediate strains of S. aureus (MRSA and VISA, respectively). Vancomycin is the current gold standard in treating serious infections caused by Gram-positive bacteria, especially MRSA. In recent clinical trials, telavancin has shown excellent efficacy in phase II and III multinational, randomized, double-blinded studies of cSSSI. In the phase II FAST 2 study, which compared telavancin 10 mg/kg intravenously q 24 h vs standard therapy (an antistaphylococcal penicillin at 2 g IV q 6 h or vancomycin 1 gm IV q 12 h), the clinical success rate in the telavancin-treated group was 96% vs 94% in the standard therapy group. In two identical phase III trials comparing telavancin versus vancomycin at the doses of the FAST 2 study for cSSSI, the clinical cure rates were 88.3% and 87.1%, respectively. Two additional phase III clinical trials investigating telavancin for use in hospital-acquired pneumonia, caused by Gram-positive bacteria are currently ongoing. Telavancin is currently under regulatory review in both the United States and Europe for the indication of treatment of cSSSI.

Cost-effectiveness analysis of linezolid, daptomycin, and vancomycin in methicillin-resistant Staphylococcus aureus: complicated skin and skin structure infection using Bayesian methods for evidence synthesis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) complicated skin and skin structure infection (cSSSI) is a prominent infection encountered in hospital and outpatient settings that is associated with high resource use for the health-care system.

OBJECTIVE

A decision analytic (DA) model was developed to evaluate the cost-effectiveness analysis (CEA) of linezolid, daptomycin, and vancomycin in MRSA cSSSI.

METHODS

Bayesian methods for evidence synthesis were used to generate efficacy and safety parameters for a DA model using published clinical trials. CEA was done from the US health-care perspective. Efficacy was defined as a successfully treated patient at the test of cure without any adverse reaction. Primary outcome was the incremental cost-effectiveness ratio between linezolid and vancomycin, daptomycin and vancomycin, and linezolid and daptomycin in MRSA cSSSI. Univariate and probabilistic sensitivity analyses were performed to test the robustness of the model.

RESULTS

The total direct costs of linezolid, daptomycin, and vancomycin were $18,057, $20,698, and $23,671, respectively. The cost-effectiveness ratios for linezolid, daptomycin, and vancomycin were $37,604, $44,086, and $52,663 per successfully treated patient, respectively. Linezolid and daptomycin were dominant strategies compared to vancomycin. However, linezolid was dominant when compared to daptomycin. The model was sensitive to the duration of daptomycin and linezolid treatment.

CONCLUSION

Linezolid and daptomycin are potentially cost-effective based on the assumptions of the DA model; however, linezolid appears to be more cost-effective compared to daptomycin and vancomycin for MRSA cSSSIs.

Perioperative synbiotic treatment to prevent infectious complications in patients after elective living donor liver transplantation: a prospective randomized study

BACKGROUND

Although the effect of synbiotic therapy using prebiotics and probiotics has been reported in hepatobiliary surgery, there are no reports of the effect on elective living-donor liver transplantation (LDLT).

METHODS

Fifty adult patients undergoing LDLT between September 2005 and June 2009 were randomized into a group receiving 2 days of preoperative and 2 weeks of postoperative synbiotic therapy (Bifidobacterium breve, Lactobacillus casei, and galactooligosaccharides [the BLO group]) and a group without synbiotic therapy (the control group). Postoperative infectious complications were recorded as well as fecal microflora before and after LDLT in each group.

RESULTS

Only 1 systemic infection occurred in the BLO group (4%), whereas the control group showed 6 infectious complications (24%), with 3 cases of sepsis and 3 urinary tract infections with Enterococcus spp (P = .033 vs BLO group). No other type of complication showed any difference between the groups.

CONCLUSIONS

Infectious complications after elective LDLT significantly decreased with the perioperative administration of synbiotic therapy.

Nosocomial infections prevalence study in a Serbian university hospital

BACKGROUND/AIM

Nosocomial infections (NI) are a serious health problem resulting in an enromous burden of excess morbidity and mortaliti rates, and health care costs. The aim of this study was to assess the prevalence of NI and to identify groups of patients at special risk for NI in the University Clinical Center, Kragujevac, Serbia.

METHODS

A period prevalence study design was used in this study. A survey of NI included all patients hospitalized in all departments in the University Clinical Center, Kragujevac.

RESULTS

Among 764 patients surveyed, the global prevalence rate of patients with at least one NI was 6.2% (95% CI = 5.6-6.8), while the prevalence of NI was 7.1%. The most frequent infections were surgical site infections (14.1%; 95% CI = 12.9-15.3), followed by pneumonia (2.3%; 95% CI = 2.1-2.5) in surgical patients. In medical wards, the most common NI were skin and subcutaneous tissue infections (1.6%; 95% CI = 1.4-1.8), and urinary infections (1.4%; 95% CI = 1.3-1.5). Overall, 85.1% NI were culture-proven; the leading pathogens were Pseudomonas species (40.0%), followed by Staphylococcus species (25.0%), Escherichia coli (22.5%), Proteus mirabilis (17.5%) and Klebsiella-Enterobacter (12.5%). Multivariate logistic regression analysis identified 3 risk factors independently associated with NI appearance: hospital stay > or =8 days (p = 0.0015), urinary catheter (p = 0.0022) and antibiotic use (p < 0.001).

CONCLUSION

This study showed that NI are a serious health problem in our hospital. The most common infections were surgical site infections, followed by skin and subcutaneous tissue infection and urinary tract infections. Nosocomial infections were most common in patients in urological and orthopedic departments, and then in intensive care units. Prolonged hospital stay, urinary catheter and antibiotic exposure were risk factors independently associated with NI appearance.

A crystal structure of a dimer of the antibiotic ramoplanin illustrates membrane positioning and a potential Lipid II docking interface

The glycodepsipeptide antibiotic ramoplanin A2 is in late stage clinical development for the treatment of infections from Gram-positive pathogens, especially those that are resistant to first line antibiotics such as vancomycin. Ramoplanin A2 achieves its antibacterial effects by interfering with production of the bacterial cell wall; it indirectly inhibits the transglycosylases responsible for peptidoglycan biosynthesis by sequestering their Lipid II substrate. Lipid II recognition and sequestration occur at the interface between the extracellular environment and the bacterial membrane. Therefore, we determined the structure of ramoplanin A2 in an amphipathic environment, using detergents as membrane mimetics, to provide the most physiologically relevant structural context for mechanistic and pharmacological studies. We report here the X-ray crystal structure of ramoplanin A2 at a resolution of 1.4 A. This structure reveals that ramoplanin A2 forms an intimate and highly amphipathic dimer and illustrates the potential means by which it interacts with bacterial target membranes. The structure also suggests a mechanism by which ramoplanin A2 recognizes its Lipid II ligand.

Linezolid versus glycopeptide or beta-lactam for treatment of Gram-positive bacterial infections: meta-analysis of randomised controlled trials

Linezolid has been approved for the treatment of patients with infections caused by Gram-positive cocci that are resistant to traditionally used antibiotics, including glycopeptides. This oxazolidinone antibiotic has been reported to have excellent pharmacokinetics and effectiveness. We did a meta-analysis of randomised controlled trials (RCTs) to clarify whether linezolid is superior to glycopeptides or beta-lactams for the treatment of Gram-positive infections. 12 RCTs, involving 6093 patients, were included. Overall, with respect to treatment success, linezolid was more effective than glycopeptides or beta-lactams (odds ratio [OR] 1.41 [95% CI 1.11-1.81]). Mortality was similar between the groups (OR 0.97 [0.79-1.19]). Linezolid was more effective than comparators in patients with skin and soft-tissue infections (OR 1.67 [1.31-2.12]) and bacteraemia (OR 2.07 [1.13-3.78]). However, there was no difference in treatment success for patients with pneumonia (OR 1.03 [0.75-1.42]). Treatment with linezolid was not associated with more adverse effects in general (OR 1.40 [0.95-2.06]); however, thrombocytopenia was recorded more commonly in patients receiving linezolid (OR 11.72 [3.66-37.57]). Although linezolid is more effective than its comparators for the empirical treatment of selected patients, several points, such as the use of less potent antistaphylococcal beta-lactams, the same all-cause mortality, and the higher probability of thrombocytopenia, should be taken into account and may limit the use of linezolid to specific patient populations or infections that are difficult to treat with other antibiotics.

Synthesis, SAR and antibacterial studies on novel chalcone oxazolidinone hybrids

With an intention to synergise the antibacterial activity of chalcones and oxazolidinones, several hybrid compounds possessing both chalcone and oxazolidinone moieties were synthesized and tested for antibacterial activity. The hybrid molecules containing heterocycles instead of aromatic ring were found to be active. A SAR study with various heterocycles resulted in a lead molecule 20, which was converted to one of the potent antibacterial compounds 27.

Synthesis of novel tricyclic oxazolidinones by a tandem SN2 and SNAr reaction: SAR studies on conformationally constrained analogues of Linezolid

A series of conformationally constrained analogues of Linezolid were synthesised by employing a tandem SN(2) and SNAr reaction as the key step and tested for antibacterial activity. While the hexahydroazolo-quinoxaline compounds were inactive, the tetrahydroazolo-benzothiazine compounds exhibited interesting antibacterial activity. The introduction of fluorine in the aromatic ring further made the compounds more potent in acetamide compounds resulting in an interesting analogue 32. However, the introduction of fluorine (analogue 34) on the already potent non-fluorine thiocarbamate 21 did not have any influence on the activity.

Bioecologic Control of Inflammation and Infection in Critical Illness

Surgical and medical emergencies and treatments are still affected by an unacceptably high rate of morbidity and mortality. Sepsis is the most common medical and surgical complication and the tenth most common cause of death. Antibiotics and antagonists and inhibitors of proinflammatory cytokines have not met expectations. Selective bowel decontamination is no longer a treatment option. After more than 30 randomized clinical trials and 30 years of dedicated efforts to combat sepsis by the use of various combinations of antibiotics, we seem ready to conclude that the vigorous use of antibiotics does not significantly reduce mortality in critically ill patients. Side effects and price constitute important obstacles, especially when it comes to use of cytokine antagonists and inhibitors.

Genomics of the fungal kingdom: Insights into eukaryotic biology

The last decade has witnessed a revolution in the genomics of the fungal kingdom. Since the sequencing of the first fungus in 1996, the number of available fungal genome sequences has increased by an order of magnitude. Over 40 complete fungal genomes have been publicly released with an equal number currently being sequenced--representing the widest sampling of genomes from any eukaryotic kingdom. Moreover, many of these sequenced species form clusters of related organisms designed to enable comparative studies. These data provide an unparalleled opportunity to study the biology and evolution of this medically, industrially, and environmentally important kingdom. In addition, fungi also serve as model organisms for all eukaryotes. The available fungal genomic resource, coupled with the experimental tractability of the fungi, is accelerating research into the fundamental aspects of eukaryotic biology. We provide here an overview of available fungal genomes and highlight some of the biological insights that have been derived through their analysis. We also discuss insights into the fundamental cellular biology shared between fungi and other eukaryotic organisms.

Linezolid versus vancomycin in treatment of complicated skin and soft tissue infections

Skin and soft tissue infections (SSTIs) are a common cause of morbidity in both the community and the hospital. An SSTI is classified as complicated if the infection has spread to the deeper soft tissues, if surgical intervention is necessary, or if the patient has a comorbid condition hindering treatment response (e.g., diabetes mellitus or human immunodeficiency virus). The purpose of this study was to compare linezolid to vancomycin in the treatment of suspected or proven methicillin-resistant gram-positive complicated SSTIs (CSSTIs) requiring hospitalization. This was a randomized, open-label, comparator-controlled, multicenter, multinational study that included patients with suspected or proven methicillin-resistant Staphylococcus aureus (MRSA) infections that involved substantial areas of skin or deeper soft tissues, such as cellulitis, abscesses, infected ulcers, or burns (<10% of total body surface area). Patients were randomized (1:1) to receive linezolid (600 mg) every 12 h either intravenously (i.v.) or orally or vancomycin (1 g) every 12 h i.v. In the intent-to-treat population, 92.2% and 88.5% of patients treated with linezolid and vancomycin, respectively, were clinically cured at the test-of-cure (TOC) visit (P=0.057). Linezolid outcomes (124/140 patients or 88.6%) were superior to vancomycin outcomes (97/145 patients or 66.9%) at the TOC visit for patients with MRSA infections (P<0.001). Drug-related adverse events were reported in similar numbers in both the linezolid and the vancomycin arms of the trial. The results of this study demonstrate that linezolid therapy is well tolerated, equivalent to vancomycin in treating CSSTIs, and superior to vancomycin in the treatment of CSSTIs due to MRSA.

Prevalence of hospital-acquired infection in a Tunisian hospital

In order to estimate the prevalence of hospital-acquired infection (HAI) and research factors associated with its occurrence, a one-day prevalence survey was conducted at the Habib Bourguiba University Hospital, Tunisia. We studied 280 patients who had been present in the same ward for at least 48 h, and who had occupied a hospital bed between 17 April 2002 (midnight) and 18 April 2002 (midnight). The overall prevalence of HAI was 17.9%. The most frequently infected sites were the lungs (32%), surgical wounds (28%) and the urinary tract (20%). Microbiological documentation was available in only 28% of HAIs, and the most frequently isolated organisms were Gram-negative rods (80.8%). Results of multiple logistic regression analysis indicated that HAI is linked to the medical category, the use of intravascular devices and antibiotic prophylaxis. This survey provided information on the prevalence of HAI in Tunisian hospitals, the breakdown of infections, and HAI predisposing factors.

[Antimicrobial resistance and bacterial virulence]

Hospitals are places with high selective pressure by antimicrobial agents. For this reason, bacteria producing nosocomial infections need to be not only virulent, but also resistant to antimicrobial agents. In the present review we analyse the effect of the acquisition of an antibiotic resistance phenotype in bacterial fitness and virulence. Besides that, we review as well the existence of common mechanisms for resistance to antimicrobial agents and bacterial virulence. In this line, we highlight the role of multidrug efflux pumps on bacterial virulence. Since opportunistic pathogens frequently have an environmental origin, we also discuss the role of natural ecosystems, as well as their potential contamination, on the selection of bacteria resistant to antimicrobial agents.