Multiresistant Gram-negative infections: a global perspective

Arginine Methylation of β-Catenin Induced by PRMT2 Aggravates LPS-Induced Cognitive Dysfunction and Depression-Like Behaviors by Promoting Ferroptosis

Depression is a prevalent and debilitating psychiatric disorder, imposing substantial societal and individual burdens. This study aims to investigate the involvement of ferroptosis and microglial polarization in the pathogenesis of depression, as well as the underlying mechanism. Increased protein arginine methyltransferase 2 (PRMT2) expression was observed in BV2 cells and the hippocampus following lipopolysaccharide (LPS) stimulation. Mechanistically, alkylation repair homolog protein 5 (ALKBH5)-mediated m6A modification enhanced the stability of PRMT2 mRNA. PRMT2 promoted arginine methylation of β-catenin and induced proteasomal degradation of β-catenin proteins, resulting in transcriptional inhibition of glutathione peroxidase 4 (GPX4). The upregulation of PRMT2 further accelerated microglia polarization by activating ferroptosis through the β-catenin-GPX4 axis. Depletion of PRMT2 improved LPS-induced depressive- and anxiety-like behaviors as well as cognitive impairment by inhibiting ferroptosis and M1 polarization of microglia. Our findings underscore the crucial involvement of the ALKBH5-PRMT2-β-catenin-GPX4 axis in ferroptosis and M1 polarization of microglia, thereby offering novel insights into the pathogenesis interventions for depression.

Assessment of the pattern of antibiotic resistance among microorganisms isolated from the culture medium prepared from hospitalized patients: A retrospective study

Background

Antibiotic resistance has become quite a challenge in the treatment of bacterial infections in the world. Therefore, the present study was conducted with the aim of investigating the pattern of antibiotic resistance among microorganisms isolated from the culture medium prepared from hospitalized patients.

Methods

The type of study was cross-sectional descriptive. The antibiotic resistance pattern of positive samples collected from patients who got hospitalized in Shahid Faghihi hospital of Shiraz University of Medical Sciences between 2020 and 2021 using the disc diffusion method according to CLSI standards was measured. Then the data were entered into SPSS version 22 software and analyzed with appropriate statistical tests.

Results

Of all positive samples, 69.7% were Gram-negative and the rest were Gram-positive. The most frequent Gram-negative bacteria were Acinetobacter baumannii (31.4%), Escherichia coli (25.3), and Klebsiella pneumonia (21.2%), and the most frequent Gram-positive bacteria were Staphylococcus aureus (79%), Coagulase-negative staphylococci (15.4%), and Enterococcus (3.6%). The resistance rate of Acinetobacter baumannii, Klebsiella pneumonia, and Pseudomonas aeroginosa against ciprofloxacin was 91.4%, 74.3%, and 52.3%; the resistance rate against gentamicin was 90.5%, 54.3%, and 43.9%; the resistance rate against Piperacillin-Tazobactam was 85.6%, 65%, and 43.1%; the resistance rate against imipenem was 97.1%, 57.9%, and 65.4%; and the resistance rate against colostin was 1.9%, 0%, and 3.4%, respectively. The resistance rate of Staphylococcus aureus against cefoxotin and vancomycin was 42.7% and 2.8%, respectively.

Conclusion

Finally, we concluded from this study that microorganisms isolated from patients have developed resistance to many commonly used antibiotics.

Exploration and Biological Evaluation of 1,3-Diamino-7H-pyrrol[3,2-f]quinazoline Derivatives as Dihydrofolate Reductase Inhibitors

Dihydrofolate reductase (DHFR), a core enzyme of folate metabolism, plays a crucial role in the biosynthesis of purines and thymidylate for cell proliferation and growth in both prokaryotic and eukaryotic cells. However, the development of new DHFR inhibitors is challenging due to the limited number of scaffolds available for drug development. Hence, we designed and synthesized a new class of DHFR inhibitors with a 1,3-diamino-7H-pyrrol[3,2-f]quinazoline derivative (PQD) structure bearing condensed rings. Compound 6r exhibited therapeutic effects on mouse models of systemic infection and thigh infection caused by methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. Moreover, methyl-modified PQD compound 8a showed a strong efficacy in a murine model of breast cancer, which was better than the effects of taxol. The findings showcased in this study highlight the promising capabilities of novel DHFR inhibitors in addressing bacterial infections as well as breast cancer.

Bacteriophage-Antibiotic Combination Therapy against Pseudomonas aeruginosa

Phage therapy is an alternative therapy that is being used as the last resource against infections caused by multidrug-resistant bacteria after the failure of standard treatments. Pseudomonas aeruginosa can cause pneumonia, septicemia, urinary tract, and surgery site infections mainly in immunocompromised people, although it can cause infections in many different patient profiles. Cystic fibrosis patients are particularly vulnerable. In vitro and in vivo studies of phage therapy against P. aeruginosa include both bacteriophages alone and combined with antibiotics. However, the former is the most promising strategy utilized in clinical infections. This review summarizes the recent studies of phage-antibiotic combinations, highlighting the synergistic effects of in vitro and in vivo experiments and successful treatments in patients.

Cross-Border Antibiotic Resistance Patterns in Burn Patients

Background: Antimicrobial resistance (AMR) is a growing problem worldwide, with differences in regional resistance patterns partially driven by local variance in antibiotic stewardship. Trauma patients transferring from Mexico have more AMR than those injured in the United States; we hypothesized a similar pattern would be present for burn patients. Patients and Methods: The registry of an American Burn Association (ABA)-verified burn center was queried for all admissions for burn injury January 2015 through December 2019 with hospital length-of-stay (LOS) longer than seven days. Patients were divided into two groups based upon burn location: United States (USA) or Mexico (MEX). All bacterial infections were analyzed. Results: A total of 73 MEX and 826 USA patients were included. Patients had a similar mean age (40.4 years MEX vs. 42.2 USA) and gender distribution (69.6% male vs. 64.4%). The MEX patients had larger median percent total body surface area burned (%TBSA; 11.1% vs. 4.3%; p ≤ 0.001) and longer hospital LOS (18.0 vs. 13.0 days; p = 0.028). The MEX patients more often had respiratory infections (16.4% vs. 7.4%; p = 0.046), whereas rates of other infections were similar. The MEX patients had higher rates of any resistant organism (47.2% of organisms MEX vs. 28.1% USA; p = 0.013), and were more likely to have resistant infections on univariable analysis; however, on multivariable analysis country of burn was no longer significant. Conclusions: Antimicrobial resistance is more common in burn patients initially burned in Mexico than those burned in the United States, but location was not a predictor of resistance compared to other traditional burn-related factors. Continuing to monitor for AMR regardless of country of burn remains critical.

Gram-negative bacilli carrying mcr gene in Brazil: a pathogen on the rise

The incidence of infections caused by resistant Gram-negative pathogens has become a critical factor in public health due to the limitation of therapeutic options for the control of infections caused, especially, by Enterobacteriaceae (Escherichia coli and Klebsiella pneumoniae), Pseudomonas spp., and Acinetobacter spp. Thus, given the increase in resistant pathogens and the reduction of therapeutic options, polymyxins were reintroduced into the clinic. As the last treatment option, polymyxins were regarded as the therapeutic key, since they were one of the few classes of antimicrobials that had activity against multidrug-resistant Gram-negative bacilli. Nonetheless, over the years, the frequent use of this antimicrobial has led to reports of resistance cases. In 2015, mcr (mobile colistin resistance), a colistin resistance gene, was described in China. Due to its location on carrier plasmids, this gene is characterized by rapid spread through conjugation. It has thus been classified as a rising threat to public health worldwide. In conclusion, based on several reports that show the emergence of mcr in different regional and climatic contexts and species of isolates, this work aims to review the literature on the incidence of the mcr gene in Brazil in different regions, types of samples identified, species of isolates, and type of carrier plasmid.

Design, Synthesis, and Bioactivity Investigation of Cyclic Lipopeptide Antibiotics Containing Eight to Nine Amino Acids

The current global issue of antibiotic resistance is serious, and there is an urgent requirement of developing novel antibiotics. Octapeptins have recently regained interest because of their activities against resistant Gram-negative bacteria. We synthesized four natural octapeptins and 33 derivatives with diverse polarity, amphiphilicity, and acid-base properties by solid-phase synthesis and investigated their in vitro antibacterial activity and renal cytotoxicity. We also assessed the structure-activity relationship and structure-toxicity relationship of the cyclic lipopeptide compounds. Some compounds showed increased activity against Gram-negative and/or Gram-positive bacteria, with improved renal cytotoxicity. C-02 showed remarkable in vitro antibacterial activity and low renal cytotoxicity. We found that C-02 showed high antibacterial activity against Escherichia coli in vivo and manifested its effects preliminarily by increasing outer membrane permeability. Therefore, C-02 might be a new antibiotic lead compound with not only high efficacy but also low renal cytotoxicity.

Antimicrobial Resistance Among Gram-Negative Bacteria Isolated in the Newborn Intensive Care Unit at ABDERREZAK-BOUHARA Hospital of Skikda, Algeria

Background: This study aimed to determine the epidemiology of gram-negative bacteria (GNB) isolated in the newborn intensive care unit (NICU) population, to assess their antibiotic susceptibility patterns and possible associated risk factors. Methods: All neonates admitted to the NICU of ABDERREZAK-BOUHARA hospital (Skikda, Algeria) with a clinical diagnosis of neonatal infections from March to May 2019 were included in the study. The extended-spectrum β-lactamase (ESBLs), plasmidic cephalosporinase (pAmpC), and carbapenemases genes were screened by polymerase chain reaction (PCR) and sequencing. PCR amplification of oprD among carbapenem-resistant Pseudomonas aeruginosa isolates was also performed. The clonal relatedness of the ESBLs isolates was studied using multilocus sequence typing (MLST). Results: Among 148 clinical specimens, 36 (24.3%) GNB strains were isolated from urine (n = 22), wound (n = 8), stool (n = 3), and blood (n = 3) samples. The bacterial species identified were Escherichia coli (n = 13), Klebsiella pneumoniae (n = 5), Enterobacter cloacae (n = 3), Serratia marcescens (n = 3), Salmonella spp. (n = 3), Proteus mirabilis (n = 1), P. aeruginosa (n = 5), and Acinetobacter baumannii (n = 3). PCR and sequencing showed that eleven Enterobacterales isolates harbored the bla_CTX-M-15 gene, two E. coli isolates harbored the bla_CMY-2 gene, and three A. baumannii isolates harbored both bla_OXA-23 and bla_OXA-51 genes. Also, five strains of P. aeruginosa were found to harbor mutations in the oprD gene. MLST showed that the K. pneumoniae strains belonged to ST13 and ST189, E. coli belonged to ST69, and E. cloacae belonged to ST214. Different risk factors that could predict positive GNB cultures were found, including female sex, Apgar score <8 at 5 min of life, enteral nutrition, antibiotic use, and extended length of hospitalization. Conclusion: Our study highlights the importance of determining the epidemiology of pathogens causing neonatal infections, their sequence types (ST), and their antibiotic susceptibility patterns to address rapidly a correct antibiotic treatment regimen.

The prevalence and distribution of aminoglycoside resistance genes

Choosing the appropriate antibiotics to treat bacterial infections has grown more challenging as a result of the emergence of antibiotic-resistant bacteria. Aminoglycosides, as broad-spectrum antibiotics, are increasingly being used clinically; however, for most effective employment of aminoglycosides, a comprehensive understanding of aminoglycoside resistance genes' prevalence and dissemination is required. Therefore, to better understand the global resistance status of aminoglycoside antibiotics and the prevalence of antibiotic-resistance genes (ARGs) in various bacterial species, this systematic review gathered relevant data from multiple studies. Two primary resistance mechanisms-aminoglycoside enzymatic modification and 16S rRNA methylation-were assessed, and the prevalence of the corresponding ARGs was described. The coexistence of aminoglycoside ARGs with other ARGs was also demonstrated, as was the relationship between aminoglycoside ARGs and resistant phenotypes. The lack of effective therapeutic agents to combat resistant pathogens presents a real threat to public health. The combination of aminoglycosides with other antibiotics may provide a novel treatment strategy.

Repurposing the Ionophore, PBT2, for Treatment of Multidrug-Resistant Neisseria gonorrhoeae Infections

Multidrug-resistant (MDR) N. gonorrhoeae is a current public health threat. New therapies are urgently needed. PBT2 is an ionophore that disrupts metal homeostasis. PBT2 administered with zinc is shown to reverse resistance to antibiotics in several bacterial pathogens. Here we show that both N. meningitidis and MDR N. gonorrhoeae are sensitive to killing by PBT2 alone. PBT2 is, thus, a candidate therapeutic for MDR N. gonorrhoeae infections.

The Exploration of Complement-Resistance Mechanisms of Pathogenic Gram-Negative Bacteria to Support the Development of Novel Therapeutics

Resistance to antibiotics in Bacteria is one of the biggest threats to human health. After decades of attempting to isolate or design antibiotics with novel mechanisms of action against bacterial pathogens, few approaches have been successful. Antibacterial drug discovery is now moving towards targeting bacterial virulence factors, especially immune evasion factors. Gram-negative bacteria present some of the most significant challenges in terms of antibiotic resistance. However, they are also able to be eliminated by the component of the innate immune system known as the complement system. In response, Gram-negative bacteria have evolved a variety of mechanisms by which they are able to evade complement and cause infection. Complement resistance mechanisms present some of the best novel therapeutic targets for defending against highly antibiotic-resistant pathogenic bacterial infections.

Design and synthesis of hybrid compounds as novel drugs and medicines

The development of highly effective conjugate chemistry approaches is a way to improve the quality of drugs and of medicines. The aim of this paper is to highlight and review such hybrid compounds and the strategies underpinning their design. A variety of unique hybrid compounds provide an excellent toolkit for novel biological activity, e.g. anticancer and non-viral gene therapy (NVGT), and as templates for killing bacteria and preventing antibiotic drug resistance. First we discuss the anticancer potential of hybrid compounds, containing daunorubicin, benzyl- or tetrahydroisoquinoline-coumarin, and cytotoxic NSAID-pyrrolizidine/indolizine hybrids, then NVGT cationic lipid-based delivery agents, where steroids or long chain fatty acids as the lipid moiety are bound to polyamines as the cationic moiety. These polyamines can be linear as in spermidine or spermine, or on a polycyclic sugar template, aminoglycosides kanamycin and neomycin B, the latter substituted with six amino groups. They are highly efficient for the delivery of both fluorescent DNA and siRNA. Molecular precedents can be found for the design of hybrid compounds in the natural world, e.g., squalamine, the first representative of a previously unknown class of natural antibiotics of animal origin. These polyamine-bile acid (e.g. cholic acid type) conjugates display many exciting biological activities with the bile acids acting as a lipidic region and spermidine as the polycationic region. Analogues of squalamine can act as vectors in NVGT. Their natural role is as antibiotics. Novel antibacterial materials are urgently needed as recalcitrant bacterial infection is a worldwide problem for human health. Ribosome inhibitors founded upon dimers of tobramycin or neomycin, bound as ethers by a 1,6-hexyl linker or a more complex diether-disulfide linker, improved upon the antibiotic activity of aminoglycoside monomers by 20- to 1200-fold. Other hybrids, linked by click chemistry, conjugated ciprofloxacin to neomycin, trimethoprim, or tedizolid, which is now in clinical trials.

The discovery of 1, 3-diamino-7H-pyrrol[3, 2-f]quinazoline compounds as potent antimicrobial antifolates

The shortage of new antibiotics makes infections caused by gram-negative (G^-) bacteria a significant clinical problem. The key enzymes involved in folate biosynthesis represent important targets for drug discovery, and new antifolates with novel mechanisms are urgently needed. By targeting to dihydrofolate reductase (DHFR), a series of 1,3-diamino-7H-pyrrol[3,2-f]quinazoline (PQZ) compounds were designed, and exhibited potent antibacterial activities in vitro, especially against multi-drug resistant G^- strains. Multiple experiments indicated that PQZ compounds contain a different molecular mechanism against the typical DHFR inhibitor, trimethoprim (TMP), and the thymidylate synthase (TS) was identified as another potential but a relatively weak target. A significant synergism between the representative compound, OYYF-175, and sulfamethoxazole (SMZ) was observed with a strong cumulative and significantly bactericidal effect at extremely low concentrations (2 μg/mL for SMZ and 0.03 pg/mL for OYYF-175), which could be resulted from the simultaneous inhibition of dihydropteroate synthase (DHPS), DHFR and TS. PQZ compounds exhibited therapeutic effects in a mouse model of intraperitoneal infections caused by Escherichia coli (E. coli). The co-crystal structure of OYYF-175-DHFR was solved and the detailed interactions were provided. The inhibitors reported represent innovative chemical structures with novel molecular mechanism of action, which will benefit the generation of new, efficacious bactericidal compounds.

Challenges to Antimicrobial Stewardship in the Countries of the Arab League: Concerns of Worsening Resistance during the COVID-19 Pandemic and Proposed Solutions

The COVID-19 pandemic is expected to worsen the global problem of antimicrobial resistance (AMR). There is a heightened interest in understanding this effect and to develop antimicrobial stewardship (AMS) interventions accordingly to curb this threat. Our paper aims to evaluate the potential magnitude of COVID-19 on AMR and AMS with a focus on the countries of the Arab league, given the social, political, and economic environments. We also evaluate obstacles in applying the rational use of antibiotics, monitoring resistance trends in the midst of the pandemic, and evaluating the impact of the economic crisis in some countries. We aim to raise awareness about the potential effects of antibiotic overuse during the pandemic and to propose practical approaches to tackle this issue.

Influence of New Compound Disinfectant From N-Dodecyl-2-(Piridin-1-Ium)Acetamide Chloride on Pathogenic Microorganisms in Poultry Houses

With the development of large-scale and intensive poultry farming, environmental disinfection has become particularly important, and the effectiveness of disinfection depends upon the performance of the disinfectants. Quaternate ammonium salt is a group of positively charged polyatomic ions with both antibacterial and antiviral activities. In order to prepare an ideal disinfectant for poultry farms, we combined a quaternate ammonium salt N-dodecyl-2-(piridin-1-ium)acetamide chloride with two other disinfectants (chlorhexidine acetate and glutaraldehyde), respectively. The antimicrobial activity, mutagenicity, and safety of the compound disinfectants were assessed by the European Standard methods using ATCC strains and clinical isolates. The results showed that both compound disinfectants meet the requirements of microbial reduction, and their effectiveness was not affected by organic matter. Quaternary ammonium disinfectant resistance genes were not detected in the strains tested indicating that bacteria are less likely to develop resistance to these compound disinfectants. Ames test showed that there was no detectable mutagenicity in the strains treated with the compound disinfectants. In vivo experiment showed that both compound disinfectants did not have significant pathological effect in mice. The bactericidal effect of the compound disinfectants was not significantly different among strains of different sources (p>0.05). Clinical tests showed that compound disinfectant had a good bactericidal effect on the air and ground of poultry farms. These results show that quaternary ammonium salts in combination with other compounds can enhance the bactericidal effect and can be used safely in poultry feedlots. This study provides a technical reference for the development of a new quaternate ammonium compound disinfectant with strong disinfection effect and low irritation.

14-year trends and resistance patterns of blood and cerebrospinal fluid cultures in children under three years old

OBJECTIVES

Bacterial infections are a major cause of UK paediatric hospitalisations, yet longitudinal data on causative organisms or antimicrobial resistance are scarce. This retrospective analysis describes trends in blood and cerebrospinal fluid (CSF) cultures and resistance patterns in children under three years old from a large UK centre.

METHODS

All culture results, and resistance data for Gram-negative rods (GNR) in blood cultures, collected between January 2005 and December 2018 were extracted from Oxford University Hospitals NHS Foundation Trust microbiology database.

RESULTS

Of 49,298 samples, 6.7% of blood and 3.1% of CSF cultures were positive for bacterial growth; 2.3% and 1.1%, respectively grew pathogens. Number of cultures taken increased over time; the proportion growing pathogens declined. Resistance of GNR to first-line antimicrobials was 9.3% to gentamicin (neonatal units), and 17.1% and 25.8% to ceftriaxone (paediatric ED and wards respectively). Resistance to any two of ceftriaxone, ciprofloxacin, gentamicin, or meropenem was ≤ 6% in both areas.

CONCLUSIONS

The proportion of positive cultures declined over time. Resistance of GNR to empirical antimicrobials were observed, but resistance to a second agent were lower. Our study informs clinician decisions on when, and to which antimicrobials, to escalate if a child is not improving on empirical therapy.

Antibacterial Potential of a Novel Peptide from the Consensus Sequence of Dermaseptin Related Peptides Secreted by Agalychnis annae

BACKGROUND

The consistently increasing reports of bacterial resistance and the reemergence of bacterial epidemics have inspired the health and scientific community to discover new molecules with antibacterial potential continuously. Frog-skin secretions constitute bioactive compounds essential for finding new biopharmaceuticals. The exact antibacterial characterization of dermaseptin related peptides derived from Agalychnis annae, is limited. The resemblance in their conserved and functionally linked genomes indicates an unprecedented opportunity to obtain novel bioactive compounds.

OBJECTIVE

In this study, we derived a novel peptide sequence and determined its antibacterial potentials.

METHODS

Consensus sequence strategy was used to design the novel and active antibacterial peptide named 'AGAAN' from skin secretions of Agalychnis annae. The in-vitro activities of the novel peptide against some bacterial strains were investigated. Time kill studies, DNA retardation, cytotoxicity, betagalactosidase, and molecular computational studies were conducted.

RESULTS

AGAAN inhibited P. aeruginosa, E. faecalis, and S. typhimurium at 20 μM concentration. E. coli and S. aureus were inhibited at 25 μM, and lastly, B. subtilis at 50 μM. Kinetics of inactivation against exponential and stationary growing bacteria was found to be rapid within 1-5 hours of peptide exposure, depending on time and concentration. The peptide displayed weak hemolytic activity between 0.01%-7.31% at the antibacterial concentrations. AGAAN efficiently induced bacterial membrane damage with subsequent cell lysis. The peptide's DNA binding shows that it also targets intracellular DNA by retarding its movement. Our in-silico molecular docking analysis displayed a strong affinity to the bacterial cytoplasmic membrane.

CONCLUSION

AGAAN exhibits potential antibacterial properties that could be used to combat bacterial resistance.

Clinical and Microbiological Outcomes of Ceftazidime-Avibactam Treatment in Adults with Gram-Negative Bacteremia: A Subset Analysis from the Phase 3 Clinical Trial Program

Introduction

This exploratory analysis assessed efficacy and safety outcomes in patients with Gram-negative bacteremia treated with ceftazidime-avibactam or comparator across five phase 3, randomized, controlled, multi-center trials in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis, hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP).

Methods

In each trial, RECLAIM and RECLAIM 3 (cIAI; NCT01499290/NCT01726023), REPRISE (cIAI/cUTI; NCT01644643), RECAPTURE (cUTI; NCT01595438/NCT01599806), and REPROVE (HAP/VAP; NCT01808092), patients were randomized 1:1 to intravenous ceftazidime-avibactam (plus metronidazole for those with cIAI) or comparators (carbapenems in > 97% patients) for 5–21 days. Efficacy assessments included clinical and microbiological responses at the test-of-cure visit in the pooled Gram-negative extended microbiologically evaluable (GNeME) population (bacteremia subset). Safety outcomes were summarized for patients with positive bacterial blood culture(s) at baseline who received ≥ 1 dose of study treatment.

Results

The overall safety population included 4050 patients (ceftazidime-avibactam, n = 2024; comparator, n = 2026). The GNeME population (bacteremia subset) comprised 101 patients (ceftazidime-avibactam, n = 54; comparator, n = 47). Clinical cure rates (all indications combined) were 47/54 (87.0%) for ceftazidime-avibactam and 39/47 (83.0%) for comparators; favorable microbiological response rates were 43/54 (79.6%) and 32/47 (68.1%), respectively. Clinical and microbiological responses in the bacteremia subset were generally similar to those in the overall set. The pattern of adverse events in patients with bacteremia was similar between treatment groups and was consistent with the known safety profile of ceftazidime-avibactam.

Conclusion

This analysis provides supportive evidence of the efficacy and safety of ceftazidime-avibactam in patients with Gram-negative bacteremia associated with cIAI, cUTI/pyelonephritis, or HAP/VAP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00506-7.

Risk factors for the development of neonatal sepsis in a neonatal intensive care unit of a tertiary care hospital of Nepal

BACKGROUND

Sepsis is an overwhelming and life-threatening response to bacteria in bloodstream and a major cause of neonatal morbidity and mortality. Understanding the etiology and potential risk factors for neonatal sepsis is urgently required, particularly in low-income countries where burden of infection is high and its epidemiology is poorly understood.

METHODS

A prospective observational cohort study was conducted between April 2016 and October 2017 in a level three NICU at a tertiary care hospital in Nepal to determine the bacterial etiology and potential risk factors for neonatal sepsis.

RESULTS

Among 142 NICU admitted neonates, 15% (21/142) and 32% (46/142) developed blood culture-positive and -negative neonatal sepsis respectively. Klebsiella pneumoniae (34%, 15/44) and Enterobacter spp. (25%, 11/44) were the most common isolates. The antimicrobial resistance of isolates to ampicillin (100%, 43/43), cefotaxime (74%, 31/42) and ampicillin-sulbactam (55%, 21/38) were the highest. BlaTEM (53%, 18/34) and blaKPC (46%, 13/28) were the commonest ESBL and carbapenemase genes respectively. In univariate logistic regression, the odds of sepsis increased with each additional day of use of invasive procedures such as mechanical ventilation (OR 1.086, 95% CI 1.008-1.170), umbilical artery catheter (OR 1.375, 95% CI 1.049-1.803), intravenous cannula (OR 1.140, 95% CI 1.062-1.225); blood transfusion events (OR 3.084, 95% CI 1.407-6.760); NICU stay (OR 1.109, 95% CI 1.040-1.182) and failure to breast feed (OR 1.130, 95% CI 1.060-1.205). Sepsis odds also increased with leukopenia (OR 1.790, 95% CI 1.04-3.082), increase in C-reactive protein (OR 1.028, 95% CI 1.016-1.040) and decrease in platelets count (OR 0.992, 95% CI 0.989-0.994). In multivariate analysis, increase in IV cannula insertion days (OR 1.147, 95% CI 1.039-1.267) and CRP level (OR 1.028, 95% CI 1.008-1.049) increased the odds of sepsis.

CONCLUSIONS

Our study indicated various nosocomial risk factors and underscored the need to improve local infection control measures so as to reduce the existing burden of sepsis. We have highlighted certain sepsis associated laboratory parameters along with identification of antimicrobial resistance genes, which can guide for early and better therapeutic management of sepsis. These findings could be extrapolated to other low-income settings within the region.

Direct detection of OXA-48-like carbapenemase variants with and without co-expression of an extended-spectrum β-lactamase from bacterial cell lysates using mass spectrometry

INTRODUCTION

Antibiotic-resistant Gram-negative bacteria are of a growing concern globally, especially those producing enzymes conferring resistance. OXA-48-like carbapenemases hydrolyze most β-lactam antibiotics, with typically low-level hydrolysis of carbapenems, but have limited effect on broad-spectrum cephalosporins. These are frequently co-expressed with extended spectrum β-lactamases, especially CTX-M-15, which typically shows high level resistance to broad-spectrum cephalosporins, yet is carbapenem susceptible. The combined resistance profile makes the need for successful detection of these specific resistance determinants imperative for effective antibiotic therapy.

OBJECTIVES

The objective of this study is to detect and identify OXA-48-like and CTX-M-15 enzymes using mass spectrometry, and to subsequently develop a method for detection of both enzyme types in combination with liquid chromatography.

METHODS

Cells grown in either broth or on agar were harvested, lysed, and, in some cases buffer-exchanged. Lysates produced from bacterial cells were separated and analyzed via liquid chromatography with mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS).

RESULTS

The intact proteins of OXA-48, OXA-181, and OXA-232 (collectively OXA-48-like herein) and CTX-M-15 were characterized and detected. Acceptance criteria based on sequence-informative fragments from each protein group were established as confirmatory markers for the presence of the protein(s). A total of 25 isolates were successfully tested for OXA-48 like (2), CTX-M-15 (3), or expression of both (7) enzymes. Thirteen isolates served as negative controls.

CONCLUSIONS

Here we present a method for the direct and independent detection of both OXA-48-like carbapenemases and CTX-M-15 β-lactamases using LC-MS/MS. The added sensitivity of MS/MS allows for simultaneous detection of at least two co-eluting, co-isolated and co-fragmented proteins from a single mass spectrum.

Is the Isolation of Pseudomonas aeruginosa Associated with Outcomes from Intra-Abdominal Infection? No, But the Receipt of an Empiric Anti-Pseudomonal Agent Is

Background: Pseudomonas aeruginosa is isolated at variable rates from intra-abdominal infections (IAI). Not all recommended empiric regimens for IAI include anti-Pseudomonas aeruginosa activity, for example, ceftriaxone and metronidazole. We hypothesized that within an adult population, Pseudomonas aeruginosa is a relatively rare isolate and has no association with mortality, and thus, empiric therapy with anti-Pseudomonas aeruginosa activity is not warranted. Patients and Methods: All IAI with positive cultures treated between 1997 and 2017 at a single institution were analyzed. This data set was divided into two cohorts, namely, those with cultures positive for Pseudomonas aeruginosa and those without. Demographics and in-hospital mortality were compared by Student t-test and χ² analysis. Predictors of isolation of Pseudomonas aeruginosa and in-hospital mortality were done by logistic regression (LR) analysis. Results: In total, 2,420 IAIs were identified, 104 (4.3%) with Pseudomonas aeruginosa and 2,316 (95.7%) without. Major demographic differences between patients with Pseudomonas aeruginosa and those without included a higher rate of health-care-associated infections (87/104, 83.7% vs. 621/2316, 26.8%; p = 0.02), a higher rate of intensive care unit (ICU)-acquired infections (23/104, 22.1% vs. 329/2316, 14.2%; p = 0.04) and a higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (17.7 ± 0.8 vs. 14.5 ± 0.2; p < 0.0001). There was an increased rate of Pseudomonas aeruginosa isolation with increasing APACHE II score. Independent predictors of isolation of Pseudomonas aeruginosa by LR included APACHE II score and days of hospitalization prior to diagnosis. Crude in-hospital mortality was similar between groups: Pseudomonas aeruginosa 14/104 (13.5%) and 276/2316 (11.9%), p = 0.79. After controlling for age, gender, APACHE II, prior transfusion, immunosuppression status, solid organ transplant status, healthcare-association, and days of hospitalization prior to diagnosis, the isolation of Pseudomonas aeruginosa was not associated with mortality. Conclusion: Pseudomonas aeruginosa is infrequently isolated and overall not associated with mortality. Nonetheless, there may be a population that merits empiric anti-Pseudomonas aeruginosa therapy: those with APACHE II ≥20 or a significant length of hospitalization prior to diagnosis.

Performance of the BD Phoenix CPO detect assay for detection and classification of carbapenemase-producing organisms

Increasing worldwide, prevalence of carbapenem-resistant gram-negative bacteria demands urgent a need for rapid detection and accurate identification of carbapenemases. The BD Phoenix CPO detect (PCD) assay possesses an in-built capacity for parallel susceptibility testing and detection of carbapenemases. Here, the ability of the assay to detect and classify carbapenemase production was tested in a collection of carbapenem-resistant Enterobacterales and non-fermentative gram-negative rods. The ability of the PCD assay to detect and classify carbapenemases was investigated in a collection of 194 clinical, carbapenem-resistant isolates (Enterobacterales [n = 65]; non-fermentative gram-negative rods [n = 129]). AST results were compared to MICS determined by gradient diffusion to determine accuracy of the PCD assay. The accuracy of the PCD assay to detect carbapenemases was compared to the results of molecular isolate characterization using a LDT multiplex carbapenemase PCR assay. All 194 isolates classified as carbapenem-resistant by reference susceptibility testing were also classified correctly as CRO by the PCD assay. Performance analysis of the PCD assay to detect carbapenemase production revealed an overall sensitivity of 98.29% and specificity of 17.95% for the detection of carbapenemase production. For the classification of carbapenemases classes A, B, and D, the PCD correctly classified 79.17% Enterobacterales and 67.16% non-fermentative gram-negative rods. The PCD assay is a reliable tool for the detection of carbapenem resistance and allows for parallel analysis of carbapenemase production. However, while sensitivity is high, low specificity in carbapenemase detection and erroneous classification demands mandatory confirmation by alternative methods, especially in non-fermentative gram-negative bacteria.

Clinical Features and Co-Infections in Invasive Pulmonary Aspergillosis in Elderly Patients

Introduction

Invasive pulmonary aspergillosis (IPA) is a potentially lethal opportunistic infection. Old age is one of the important risk factors of IPA. However, data regarding the clinical characteristics and prognostic factors of elderly patients with IPA are limited, with data regarding co-infection of other bacteria or fungi even scarcer.

Methods

We performed a retrospective study of elderly patients (aged≥60) with IPA diagnosed in the First Affiliated Hospital of Sun Yat-sen University from January 2000 to December 2019. Data collection included demographic characteristics, premorbid conditions, underlying diseases, clinical manifestations, therapeutic procedures, and pathogenic detection. Associated factors were analyzed by logistic regression analysis.

Results

A total of 97 elderly patients (75 males, 22 females) with IPA were included. The all-cause mortality rate was 36.1% (35/97). Body mass index (BMI) (adjusted odds ratio (OR) 1.27, 95% confidence interval (CI) 1.08–1.50, P=0.01), solid organ malignancy (adjusted OR 5.37, 95% CI 1.35–21.33, P=0.02), and co-infections (adjusted OR 5.73, 95% CI 1.40–23.51, P=0.02) were associated with mortality in the elderly patients with IPA. Nearly, 76.3% (74/97) of the patients developed co-infections. Most of the infections (55/74, 74.3%) involved the lung. A total of 77 strains of bacteria were isolated, and Gram-negative bacteria (63/77, 81.3%) were predominant. Patients with co-infections are older (72.3±7.6 vs 67.4±7.4, P=0.04), prone to admit to the intensive care unit (ICU) (59.5% vs 26.1%, P=0.01), and present lymphopenia (60.8% vs 26.1%, P=0.004). In multivariate analysis, ICU admission (adjusted OR 4.57, 95% CI 1.53–13.67, P=0.01), and lymphopenia (adjusted OR 4.82, 95% CI 1.62–14.38, P=0.01) were significantly associated with co-infection in the elderly patients with IPA.

Conclusion

IPA is a fatal disease in the elderly population. Co-infection is closely associated with mortality. Lymphopenia could be an indicator for co-infection in the elderly patients with IPA.

Direct detection of intact Klebsiella pneumoniae carbapenemase variants from cell lysates: Identification, characterization and clinical implications

Introduction

Carbapenemase-producing organisms (CPOs) are a growing threat to human health. Among the enzymes conferring antibiotic resistance produced by these organisms, Klebsiella pneumoniae carbapenemase (KPC) is considered to be a growing global health threat. Reliable and specific detection of this antibiotic resistance-causing enzyme is critical both for effective therapy and to mitigate further spread.

Objectives

The objective of this study is to develop an intact protein mass spectrometry-based method for detection and differentiation of clinically-relevant KPC variants directly from bacterial cell lysates. The method should be specific for any variant expressed in multiple bacterial species, limit false positive results and be rapid in nature to directly influence clinical outcomes.

Methods

Lysates obtained directly from bacterial colonies were used for intact protein detection using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Bottom-up and top-down proteomic methods were used to characterize the KPC protein targets of interest. Comparisons between KPC-producing and KPC-non-producing isolates from a wide variety of species were also performed.

Results

Characterization of the mature KPC protein revealed an unexpected signal peptide cleavage site preceding an AXA signal peptide motif, modifying the molecular weight (MW) of the mature protein. Taking the additional AXA residues into account allowed for direct detection of the intact protein using top-down proteomic methods. Further validation was performed by transforming a KPC-harboring plasmid into a negative control strain, followed by MS detection of the KPC variant from the transformed cell line. Application of this approach to clearly identify clinically-relevant variants among several species is presented for KPC-2, KPC-3, KPC-4 and KPC-5.

Conclusion

Direct detection of these enzymes contributes to the understanding of occurrence and spread of these antibiotic-resistant organisms. The ability to detect intact KPC variants via a simple LC-MS/MS approach could have a direct and positive impact on clinical therapy, by providing both direction for epidemiological tracking and appropriate therapy.

Trends in antimicrobial resistance among bacteria causing septic arthritis in adults in a single center: A 15-years retrospective analysis

Septic arthritis (SA) is commonly associated with Staphylococcal or Streptococcal infections. Overtime, there has been a global increase in the distribution of antimicrobial resistance within both Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria such as extended-spectrum beta-lactamase (ESBL) positive Enterobacteriacea. The aim of this study was to determine whether this change in epidemiology similarly affected the distribution of resistant pathogens causing SA. The study was conducted at the Shaare Zedek Medical Center in Jerusalem, Israel. All adult patients diagnosed with SA during 2002-2016 were included in the cohort. Antimicrobial resistance trends were examined over three periods: 2002-2009, 2010-2013, and 2014-2016. Of 85 patients with SA, mean age of patients was 66.8 (± 20.3) years, with male predominance (n = 62, 66%). Most SA cases involved native knee joints and more than 85% (n = 80) were acquired in the community. The most common isolates were S. aureus (n = 38, 45%) and beta-hemolytic streptococci (n = 13, 15%). MRSA SA was diagnosed in 8% of all SA cases (n = 7). An increasing, although non-significant trend in MRSA SA was observed during the study period (p = 0.3). Gram-negative infections were uncommon (n = 14). No ESBL-positive or carbapenem-resistant Enterobacteriacea were detected. Over a 15-year study period, no significant increase in resistant pathogens causing SA was observed. In the era of antibiotic stewardship, these results strengthen our practice of administering narrow-spectrum antimicrobials empirically for SA. However, our findings cannot be generalized to regions with higher rates of MRSA in the community.

Rational Substitution of ε-Lysine for α-Lysine Enhances the Cell and Membrane Selectivity of Pore-Forming Melittin

Here, we present a rational approach that enhances the membrane selectivity of a prolific pore-forming peptide, melittin, based on experimental observations that the cationic polymer, ε-polylysine, disrupts bacterial membranes with greater affinity over mammalian cells when compared to poly-l-lysine and poly-d-lysine. We systematically replaced three α-lysine residues in melittin with ε-lysine residues and identified key residues that are important for cytotoxicity. We then assessed the antimicrobial properties of the modified peptides which carry two or three ε-lysyl residues. Two modified melittin peptides displayed rapid bactericidal properties against antibiotic-resistant strains, low innate resistance development by pathogenic bacteria, remained nonimmunogenic for T lymphocytes, and increased bioavailability in tear fluids. In proof-of-concept in vivo experiments, one of the peptides was noncytotoxic for ocular surfaces and had comparable antimicrobial efficacy to that of fluoroquinolone antibiotics. The results uncover a simple and potential strategy that can enhance the membrane selectivity of cytolytic peptides by ε-lysylation.

Long-Term Surveillance of Antibiotic Prescriptions and the Prevalence of Antimicrobial Resistance in Non-Fermenting Gram-Negative Bacilli

The increasing emergence of multidrug-resistant (MDR) bacteria has been recognized as a public health threat worldwide. Hospitalized patients and outpatients are commonly infected by non-fermenting Gram-negative bacilli (NFGNB), particularly the Acinetobacter calcoaceticus-Acinetobacter baumannii complex (ACB) and Pseudomonas aeruginosa. Antimicrobial agents are critical for treating the nosocomial infections caused by NFGNB. The aim of this study was to assess antimicrobial resistance and the use of antimicrobial agents. The bacterial isolates of 638,152 specimens from both inpatients and outpatients, retrieved from 2001 to 2008 at a medical center in central Taiwan, were examined for their susceptibility to various antimicrobial agents, including cefepime, imipenem, ciprofloxacin, gentamicin, amikacin, meropenem, and levofloxacin. Administrated prescriptions of the monitored antibiotics were analyzed using the Taiwan National Health Insurance Research Database (NHIRD). Our results show that the defined daily doses (DDDs) for cefepime, imipenem, and ciprofloxacin increased with time, and a trend toward reduced antimicrobial sensitivities of both ACB and P. aeruginosa was noticeable. In conclusion, the antimicrobial sensitivities of ACB and P. aeruginosa were reduced with the increased use of antibiotics. Continuous surveillance of antibiotic prescriptions and the prevalence of emerging resistance in nosocomial infections is warranted.

Next-generation strategy for treating drug resistant bacteria: Antibiotic hybrids

Resistance against nearly all antibiotics used clinically have been documented in bacteria. There is an ever-increasing danger caused by multidrug-resistant Gram-negative bacteria in both hospital and community settings. In Gram-negative bacteria, intrinsic resistance to currently available antibiotics is mainly due to overexpressed efflux pumps which are constitutively present and also presence of protective outer membrane. Combination therapy, i.e., use of two or more antibiotics, was thought to be an effective strategy because it took advantage of the additive effects of multiple antimicrobial mechanisms, lower risk of resistance development and lower mortality and improved clinical outcome. However, none of the benefits were seen in in vivo studies. Antibiotic hybrids are being used to challenge the growing drug resistance threat and increase the usefulness of current antibiotic arsenal. Antibiotic hybrids are synthetic constructs of two molecules which are covalently linked. These could be two antibiotics or antibiotic with an adjuvant (efflux pump inhibitor, siderophore, etc.) which increases the access of the antibiotics to the target. The concepts, developments and challenges in the future use of antibiotic hybrids are discussed here. Majority of the studies have been conducted on fluoroquinolones and aminoglycosides molecules. The antibiotic tobramycin has the property to enhance the action of antimicrobial agents against which the multidrug-resistant Gram-negative bacteria were earlier resistant, and thus potentiating the action of legacy antibiotics. Antibiotic hybrids may have a role as the silver bullet in Gram-negative bacteria to overcome drug resistance as well as extend the spectrum of existing antibiotics.

The Transmissibility of Antibiotic-Resistant Enterobacteriaceae in Intensive Care Units

Background

The global emergence of infections caused by Enterobacteriaceae resistant to expanded-spectrum cephalosporins (ESCs) in intensive care units (ICUs) is, at least partly, driven by cross-transmission. Yet, individual transmission capacities of bacterial species have not been quantified.

Methods

In this post hoc analysis of a multicenter study in 13 European ICUs, prospective surveillance data and a mathematical model were used to estimate transmission capacities and single-admission reproduction numbers (R_A) of Escherichia coli and non–E. coli Enterobacteriaceae (non-EcE), all being ESC resistant. Surveillance was based on a chromogenic selective medium for ESC-resistant Enterobacteriaceae, allowing identification of E. coli and of Klebsiella, Enterobacter, Serratia, and Citrobacter species, grouped as non-EcE.

Results

Among 11420 patients included, the admission prevalence was 3.8% for non-EcE (74% being Klebsiella pneumoniae) and 3.3% for E. coli. Acquisition rates were 7.4 and 2.6 per 100 admissions at risk for non-EcE and E. coli, respectively. The estimated transmission capacity of non-EcE was 3.7 (95% credibility interval [CrI], 1.4–11.3) times higher than that of E. coli, yielding single-admission reproduction numbers (R_A) of 0.17 (95% CrI, .094–.29) for non-EcE and 0.047 (95% CrI, .018–.098) for E. coli.

Conclusions

In ICUs, non-EcE, mainly K. pneumoniae, are 3.7 times more transmissible than E. coli. Estimated R_A values of these bacteria were below the critical threshold of 1, suggesting that in these ICUs outbreaks typically remain small with current infection control policies.

Control of Gram-negative multi-drug resistant microorganisms in an Italian ICU: Rapid decline as a result of a multifaceted intervention, including conservative use of antibiotics

BACKGROUND

Gram-negative Multi-Drug-Resistant Organisms (GNMDROs) cause an increasing burden of disease in Intensive Care Units (ICUs). We deployed a multifaceted intervention to control selection and transmission of GNMDROs and to estimate at which rate GNMDROs would decline with our interventional bundle.

METHODS

Interventions implemented in 2015: in-ward Antimicrobial-Stewardship-Program for appropriate management of antimicrobial prescription; infection monitoring with nasal/rectal swabs and repeated procalcitonin assays; 24 h microbiological support (since 2016); prevention of catheter-related infections, VAPs and in-ward GNMDROs transmission; education of ICU personnel. In May 2017, epidemiological, clinical and microbiological data were collected and retrospectively analyzed. Rates of resistance in Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii, as well as percentages of resistance among all Gram-negative bacteria were compared during the study period.

RESULTS

Of 668 patients, at least one isolate was obtained from 399 patients. The proportions of patients with infection and with Gram-negative isolates were even across the 5 semesters (p = 0.8). For Klebsiella pneumoniae, the number of strains resistant to carbapenems fell from 94% to 6% (p < 0.001). Significant drops were also observed for Pseudomonas aeruginosa and Acinetobacter baumannii. Percentages of resistance for all Gram-negative isolates fell from 91% to 13% (p < 0.0001). The reduction in antibiotic prescription translated in a considerable reduction of pharmacy costs. Multivariate models confirmed that the hospitalization semester was the most relevant independent predictor of resistance among Gram-negative bacteria.

CONCLUSIONS

Our experience provides further evidence that a multi-faceted intervention, aimed to reduce selection and transmission of GNMDROs with efficient microbiological support, may yield remarkable results in a short time interval.

Bacteremia in Childhood Life-Threatening Infections in Urban Gambia: EUCLIDS in West Africa

Background

The limited availability of microbiology services in sub-Saharan Africa impedes accurate diagnosis of bacterial pathogens and understanding of trends in prevalence and antibiotic sensitivities. We aimed to characterize bacteremia among hospitalized children in The Gambia and to identify factors associated with bacteremia and mortality.

Methods

We prospectively studied children presenting with suspected severe infection to 2 urban hospitals in The Gambia, between January 2013 and September 2015. Demographic and anthropometric data, clinical features, management, and blood culture results were documented. Urine screens for antibiotic activity were performed in a subset of participants.

Results

Of 411 children enrolled (median age, 29 months; interquartile range, 11–82), 79.5% (325 of 409) reported prehospital antibiotic use. Antimicrobial activity by urinary screen for antibiotic activity was detected in 70.8% (n = 80 of 113). Sixty-six bacterial pathogens were identified in 65 (15.8%) participants and Staphylococcus aureus predominated. Gram-positive organisms were more commonly identified than Gram-negative (P < .01). Antibiotic resistance against first-line antimicrobials (ampicillin and gentamicin) was common among Gram-negative bacteria (39%; range, 25%–100%). Factors significantly associated with bacteremia included the following: gender, hydration status, musculoskeletal examination findings, admission to the Medical Research Council The Gambia at London School of Hygiene & Tropical Medicine hospital, and meeting sepsis criteria. Those associated with increased mortality were presence of a comorbidity, clinical pallor, tachypnea, and altered consciousness. Tachycardia was associated with reduced mortality.

Conclusions

The bacteremia rate in children with suspected childhood life-threatening infectious diseases in The Gambia is high. The pattern of pathogen prevalence and antimicrobial resistance has changed over time compared with previous studies illustrating the importance of robust bacterial surveillance programs in resource-limited settings.

Clinical outcomes following treatment of Enterobacter species pneumonia with piperacillin/tazobactam compared to cefepime or ertapenem

BACKGROUND

Enterobacter spp. are a common cause of nosocomial pneumonia and treatment can be complicated by AmpC resistance. Carbapenems are the treatment of choice; however, alternatives are needed. Cefepime has been shown to be non-inferior to carbapenems. There are limited data to support the use of piperacillin/tazobactam. The objective of this study was to determine if piperacillin/tazobactam is non-inferior to cefepime or ertapenem for Enterobacter pneumonia treatment.

OBJECTIVES

To compare the rate of clinical cure in patients with Enterobacter pneumonia receiving definitive treatment with piperacillin/tazobactam, cefepime, or ertapenem. Secondary outcomes included hospital mortality, infection-related length of stay, duration of mechanical ventilation, recurrent pneumonia, and resistance.

METHODS

Retrospective, single-center study.

RESULTS

Of 114 patients included, 59 received definitive treatment with piperacillin/tazobactam and 55 received cefepime or ertapenem. There was no difference in the proportion of patients who achieved clinical cure in the piperacillin/tazobactam group compared to the cefepime or ertapenem group (76.3% vs. 87.3%, P = 0.13). Treatment group was not associated with clinical cure when controlling for confounders in multivariable logistic regression (adjusted odds ratio [OR] 0.59, 95% confidence interval [CI] 0.15-2.37). The rate of recurrent pneumonia was 11.4% in the piperacillin/tazobactam group and 6.7% in the cefepime or ertapenem group (P = 0.48). Other secondary outcomes did not differ between the groups.

CONCLUSIONS

In this retrospective study of patients with Enterobacter pneumonia, clinical cure with piperacillin/tazobactam was comparable to that with cefepime or ertapenem; however, a prospective trial with a larger population is needed to determine if definitive treatment with piperacillin/tazobactam is non-inferior to definitive treatment with cefepime or ertapenem.

Microbial Diversity and Antimicrobial Resistance Profile in Microbiota From Soils of Conventional and Organic Farming Systems

Soil is one of the biggest reservoirs of microbial diversity, yet the processes that define the community dynamics are not fully understood. Apart from soil management being vital for agricultural purposes, it is also considered a favorable environment for the evolution and development of antimicrobial resistance, which is due to its high complexity and ongoing competition between the microorganisms. Different approaches to agricultural production might have specific outcomes for soil microbial community composition and antibiotic resistance phenotype. Therefore in this study we aimed to compare the soil microbiota and its resistome in conventional and organic farming systems that are continually influenced by the different treatment (inorganic fertilizers and pesticides vs. organic manure and no chemical pest management). The comparison of the soil microbial communities revealed no major differences among the main phyla of bacteria between the two farming styles with similar soil structure and pH. Only small differences between the lower taxa could be observed indicating that the soil community is stable, with minor shifts in composition being able to handle the different styles of treatment and fertilization. It is still unclear what level of intensity can change microbial composition but current conventional farming in Central Europe demonstrates acceptable level of intensity for soil bacterial communities. When the resistome of the soils was assessed by screening the total soil DNA for clinically relevant and soil-derived antibiotic resistance genes, a low variety of resistance determinants was detected (resistance to β-lactams, aminoglycosides, tetracycline, erythromycin, and rifampicin) with no clear preference for the soil farming type. The same soil samples were also used to isolate antibiotic resistant cultivable bacteria, which were predominated by highly resistant isolates of Pseudomonas, Stenotrophomonas, Sphingobacterium and Chryseobacterium genera. The resistance of these isolates was largely dependent on the efflux mechanisms, the soil Pseudomonas spp. relying mostly on RND, while Stenotrophomonas spp. and Chryseobacterium spp. on RND and ABC transporters.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Structural and Functional Studies of Bacterial Enolase, a Potential Target against Gram-Negative Pathogens

Enolase is a glycolytic metalloenzyme involved in carbon metabolism. The advantage of targeting enolase lies in its essentiality in many biological processes such as cell wall formation and RNA turnover and as a plasminogen receptor. We initially used a DARTS assay to identify enolase as a target in Escherichia coli. The antibacterial activities of α-, β-, and γ-substituted seven-member ring tropolones were first evaluated against four strains representing a range of Gram-negative bacteria. We observed that the chemical properties and position of the substituents on the tropolone ring play an important role in the biological activity of the investigated compounds. Both α- and β-substituted phenyl derivatives of tropolone were the most active with minimum inhibitory concentrations in the range of 11-14 μg/mL. The potential inhibitory activity of the synthetic tropolones was further evaluated using an enolase inhibition assay, X-ray crystallography, and molecular docking simulations. The catalytic activity of enolase was effectively inhibited by both the naturally occurring β-thujaplicin and the α- and β-substituted phenyl derivatives of tropolones with IC₅₀ values in range of 8-11 μM. Ligand binding parameters were assessed by isothermal titration calorimetry and differential scanning calorimetry techniques and agreed with the in vitro data. Our studies validate the antibacterial potential of tropolones with careful consideration of the position and character of chelating moieties for stronger interaction with metal ions and residues in the enolase active site.

HEXIM1 Peptide Exhibits Antimicrobial Activity Against Antibiotic Resistant Bacteria Through Guidance of Cell Penetrating Peptide

The emergence of antibiotic resistant bacteria is one of the biggest threats to human health worldwide. In 2017, World Health Organization listed the world’s most dangerous antibiotic-resistant bacteria or “superbugs,” such as carbapenem-resistant Pseudomonas aeruginosa and Escherichia coli, indicating the highest priority needs for new antibiotics. The possibility that such infectious diseases may soon be untreatable, due to decreased antibiotic efficacy, creates an urgent need for novel and alternative antimicrobials. Antimicrobial peptides are naturally occurring small molecules found in the innate immunity of mammals, plants and bacteria, and are potentially therapeutic candidates against drug-resistant bacteria. In this study, we examine the antimicrobial activities of the cytotoxic peptides derived from the basic region (BR) of the human hexamethylene bisacetamide-inducible protein 1 (HEXIM1). We found that, when fused with a cell penetrating peptide, the HEXIM1 BR peptide and its derivative, BR-RRR12, exhibited inhibitory activities against selected “superbugs.” Negligible effects on the viability of human keratinocyte cell line were observed when the bactericidal dosages of HEXIM1 BR peptides were used. Different killing kinetics were observed between the membrane permeabilizing antimicrobial peptides and HEXIM1 BR peptides, suggesting that a different antimicrobial mechanism might be utilized by the HEXIM1 BR peptides. Using an in vitro translation system based on E. coli lysates, we found that HEXIM1 BR peptides blocked bacterial translation. Taken together, we identify the HEXIM1 BR peptide as a novel antimicrobial peptide with potent inhibitory activity against antibiotic-resistant “superbugs.”

Impact of Gram-negative bacteria on the treatment of venous leg ulcers

Gram-negative germs with and without multi-resistance are garnering more and more importance. The aim of this study was to investigate the frequency and rate of resistance against antibiotics and to clarify the impact of Gram-negative bacteria, especially with high rates of resistance, for the treatment of venous leg ulcers. This is a retrospective, monocentric, non-randomised open study. Included were all data within 1 year of bacterial swabs of venous leg ulcers. We performed summarization, pooling, and descriptive analysis for frequencies and crossover. We analysed 679 swabs of 285 patients with venous leg ulcers. The mean patient age was 69.78 years. There were 76.1% Gram-positive and 58.2% Gram-negative germs detected; 56.5% of the swabs showed multi-resistance. Gram-negative bacteria were associated with more pain. Exacerbation and relevant aggravation of wounds that led to stationary treatment occurred more frequently. With polihexanid treatment, we saw less Gram-negative flora. This study showed an immediate impact of Gram-negative germs on the patient's pain, the risk for aggravation, and the choice of treatment. Further studies for prophylaxis and treatment of Gram-negative germs in venous leg ulcer therapy are needed.

Rapid Increase in Prevalence of Carbapenem-Resistant Enterobacteriaceae (CRE) and Emergence of Colistin Resistance Gene mcr-1 in CRE in a Hospital in Henan, China

The global spread of carbapenem-resistant Enterobacteriaceae (CRE) is one of the most severe threats to human health in a clinical setting. The recent emergence of plasmid-mediated colistin resistance gene mcr-1 among CRE strains greatly compromises the use of colistin as a last resort for the treatment of infections caused by CRE. This study aimed to understand the current epidemiological trends and characteristics of CRE from a large hospital in Henan, the most populous province in China. From 2014 to 2016, a total of 7,249 Enterobacteriaceae isolates were collected from clinical samples, among which 18.1% (1,311/7,249) were carbapenem resistant. Carbapenem-resistant Klebsiella pneumoniae and carbapenem-resistant Escherichia coli were the two most common CRE species, with Klebsiella pneumoniae carbapenemases (KPC) and New Delhi metallo-β-lactamases (NDM), respectively, responsible for the carbapenem resistance of the two species. Notably, >57.0% (n = 589) of the K. pneumoniae isolates from the intensive care unit were carbapenem resistant. Furthermore, bla_NDM-5 and mcr-1 were found to coexist in one E. coli isolate, which exhibited resistance to almost all tested antibiotics. Overall, we observed a significant increase in the prevalence of CRE isolates during the study period and suggest that carbapenems may no longer be considered to be an effective treatment for infections caused by K. pneumoniae in the studied hospital.

Antibiotic Hybrids: the Next Generation of Agents and Adjuvants against Gram-Negative Pathogens?

The global incidence of drug-resistant Gram-negative bacillary infections has been increasing, and there is a dire need to develop novel strategies to overcome this problem. Intrinsic resistance in Gram-negative bacteria, such as their protective outer membrane and constitutively overexpressed efflux pumps, is a major survival weapon that renders them refractory to current antibiotics. Several potential avenues to overcome this problem have been at the heart of antibiotic drug discovery in the past few decades. We review some of these strategies, with emphasis on antibiotic hybrids either as stand-alone antibacterial agents or as adjuvants that potentiate a primary antibiotic in Gram-negative bacteria. Antibiotic hybrid is defined in this review as a synthetic construct of two or more pharmacophores belonging to an established agent known to elicit a desired antimicrobial effect. The concepts, advances, and challenges of antibiotic hybrids are elaborated in this article. Moreover, we discuss several antibiotic hybrids that were or are in clinical evaluation. Mechanistic insights into how tobramycin-based antibiotic hybrids are able to potentiate legacy antibiotics in multidrug-resistant Gram-negative bacilli are also highlighted. Antibiotic hybrids indeed have a promising future as a therapeutic strategy to overcome drug resistance in Gram-negative pathogens and/or expand the usefulness of our current antibiotic arsenal.