Resistant Gram-positive Pathogens Research Articles

Antibiotic Resistance to Molecules Commonly Prescribed for the Treatment of Antibiotic-Resistant Gram-Positive Pathogens: What Is Relevant for the Clinician?

Antibiotic resistance in Gram-positive pathogens is a relevant concern, particularly in the hospital setting. Several antibiotics are now available to treat these drug-resistant pathogens, such as daptomycin, dalbavancin, linezolid, tedizolid, ceftaroline, ceftobiprole, and fosfomycin. However, antibiotic resistance can also affect these newer molecules. Overall, this is not a frequent phenomenon, but it is a growing concern in some settings and can compromise the effectiveness of these molecules, leaving few therapeutic options. We reviewed the available evidence about the epidemiology of antibiotic resistance to these antibiotics and the main molecular mechanisms of resistance, particularly methicillin-resistant Sthaphylococcus aureus, methicillin-resistant coagulase-negative staphylococci, vancomycin-resistant Enterococcus faecium, and penicillin-resistant Streptococcus pneumoniae. We discussed the interpretation of susceptibility tests when minimum inhibitory concentrations are not available. We focused on the risk of the emergence of resistance during treatment, particularly for daptomycin and fosfomycin, and we discussed the strategies that can be implemented to reduce this phenomenon, which can lead to clinical failure despite appropriate antibiotic treatment. The judicious use of antibiotics, epidemiological surveillance, and infection control measures is essential to preserving the efficacy of these drugs.

Treatment challenges in the management of difficult-to-treat gram-positive infections: A consensus view apropos therapeutic role of novel anti-MRSA antibiotics, levonadifloxacin (IV) and alalevonadifloxacin (oral)

PurposeTreatment of antibiotic-resistant Gram-positive infections (GPIs), including methicillin-resistant Staphylococcus aureus (MRSA) is becoming increasingly difficult, particularly in patients with multiple co-morbidities who require antibiotics with greater safety and a consistent pharmacokinetic/pharmacodynamic (PK/PD) profile. Such difficult-to-treat GPIs are often associated with poor outcomes, extended hospital stay and increased expenditure. This can be partly attributed to the limited safety and aberrant PK/PD profile of existing anti-MRSA antibiotics. In this context, intravenous levonadifloxacin and its oral prodrug alalevonadifloxacin are novel anti-MRSA antibiotics that have significant advantages over conventional anti-Gram-positive antibiotics. The purpose of this paper was to generate a consensus on the optimal use of levonadifloxacin and alalevonadifloxacin for tackling resistant Gram-positive infections in patients with multiple co-morbidities. MethodUsing a modified Delphi approach that combines critical appraisal of evidence and expert opinion, therapeutic use of levonadifloxacin and alalevonadifloxacin in various clinical scenarios and specific unmet conditions was deliberated. Fifteen expert members from medicine, critical-care, emergency, microbiology, and intensive-care disciplines participated and voted on 11 pre-conceived statements. When there was at least 70 % agreement, a consensus was reached. ResultsFollowing the voting, agreements were reached on 10 out of the 11 statements. Broadly, a consensus was reached in defining the therapeutic role of levonadifloxacin and alalevonadifloxacin in the treatment of various clinical indications involving resistant Gram-positive pathogens, including MRSA, in patients with co-morbidities, such as co-existing or increased risk for kidney dysfunction or hepatic disease and/or immunosuppression; also, in therapeutically challenging conditions caused by Gram-positive bacteria such as bacteraemia, bone and joint infection, diabetic foot infection, febrile neutropenia, and hospital-acquired pneumonia. ConclusionsThis consensus supports the therapeutic use of levonadifloxacin and alalevonadifloxacin in the treatment of antibiotic-resistant GPIs, including those caused by MRSA and certain polymicrobial infections, in patients with multiple co-morbidities requiring drug with adequate safety and consistent efficacy.

Experimental Evaluation of the Hypersensitivity Reactions of a New Glycopeptide Antibiotic Flavancin in Animal Models.

Glycopeptide antibiotics are still in demand in clinical practice for treating infections caused by resistant gram-positive pathogens; however, their use is limited due to severe adverse reactions. Their predominant types of side effects are immunoglobulin E-mediated or nonmediated hypersensitivity reactions. Therefore, the development of new glycopeptide antibiotics with improved toxicity profiles remains an important objective in advancing modern antimicrobial agents. We investigated a new eremomycin aminoalkylamide flavancin, its anaphylactogenic properties, influence on histamine levels in blood plasma, pseudoallergic inflammatory reaction on concanavalin A and the change in the amount of flavancin in the blood plasma after administration. It has been shown that flavancin does not demonstrate anaphylactogenic properties. The injection of flavancin resulted in a level of histamine in the blood three times lower than that caused by vancomycin. The therapeutic dose of vancomycin led to a statistically significant increase in the concanavalin A response index compared to flavancin (54% versus 3.7%). Thus, flavancin does not cause a pseudo-allergic reaction. The rapid decrease in flavancin concentration in the blood and the low levels of histamine in the plasma lead us to assume that any pseudoallergic reactions resulting from flavancin application, if they do occur in clinical practice, will be significantly less compared to the use of vancomycin.

Riboflavin-Vancomycin Conjugate Enables Simultaneous Antibiotic Photo-Release and Photodynamic Killing against Resistant Gram-Positive Pathogens.

Decades of antibiotic misuse have led to alarming levels of antimicrobial resistance, and the development of alternative diagnostic and therapeutic strategies to delineate and treat infections is a global priority. In particular, the nosocomial, multidrug-resistant "ESKAPE" pathogens such as Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp (VRE) urgently require alternative treatments. Here, we developed light-activated molecules based on the conjugation of the FDA-approved photosensitizer riboflavin to the Gram-positive specific ligand vancomycin to enable targeted antimicrobial photodynamic therapy. The riboflavin-vancomycin conjugate proved to be a potent and versatile antibacterial agent, enabling the rapid, light-mediated, killing of MRSA and VRE with no significant off-target effects. The attachment of riboflavin on vancomycin also led to an increase in antibiotic activity against S. aureus and VRE. Simultaneously, we evidenced for the first time that the flavin subunit undergoes an efficient photoinduced bond cleavage reaction to release vancomycin, thereby acting as a photoremovable protecting group with potential applications in drug delivery.

Synthesis of 1-(2-Hydroxyphenyl)- and (3,5-Dichloro-2-hydroxyphenyl)-5-oxopyrrolidine-3-carboxylic Acid Derivatives as Promising Scaffolds for the Development of Novel Antimicrobial and Anticancer Agents.

Increasing antimicrobial resistance among Gram-positive pathogens and pathogenic fungi remains one of the major public healthcare threats. Therefore, novel antimicrobial candidates and scaffolds are critically needed to overcome resistance in Gram-positive pathogens and drug-resistant fungal pathogens. In this study, we explored 1-(2-hydroxyphenyl)-5-oxopyrrolidine-3-carboxylic acid and its 3,5-dichloro-2-hydroxyphenyl analogue for their in vitro antimicrobial activity against multidrug-resistant pathogens. The compounds showed structure-dependent antimicrobial activity against Gram-positive pathogens (S. aureus, E. faecalis, C. difficile). Compounds 14 and 24b showed promising activity against vancomycin-intermediate S. aureus strains, and favorable cytotoxic profiles in HSAEC-1 cells, making them attractive scaffolds for further development. 5-Fluorobenzimidazole, having a 3,5-dichloro-2-hydroxyphenyl substituent, was found to be four-fold, and hydrazone, with a thien-2-yl fragment, was two-fold stronger than clindamycin against methicillin resistant S. aureus TCH 1516. Moreover, hydrazone, bearing a 5-nitrothien-2-yl moiety, showed promising activity against three tested multidrug-resistant C. auris isolates representing major genetic lineages (MIC 16 µg/mL) and azole-resistant A. fumigatus strains harboring TR34/L98H mutations in the CYP51A gene. The anticancer activity characterization demonstrated that the 5-fluorobenzimidazole derivative with a 3,5-dichloro-2-hydroxyphenyl substituent showed the highest anticancer activity in an A549 human pulmonary cancer cell culture model. Collectively these results demonstrate that 1-(2-hydroxyphenyl)-5-oxopyrrolidine-3-carboxylic acid derivatives could be further explored for the development of novel candidates targeting Gram-positive pathogens and drug-resistant fungi.

The Challenge of Emerging Resistant Gram-Positive Pathogens in Hip and Knee Periprosthetic Joint Infections.

An increase in resistant bacterial pathogens has occurred over the last 4 decades. Careful patient selection and improving or correcting risk factors for periprosthetic joint infection (PJI) before elective surgical treatment are strongly recommended. Appropriate microbiological methods, including those used to detect and grow Cutibacterium acnes, are recommended. Antimicrobial agents used in the prevention or management of infection should be selected appropriately and the duration of therapy should be carefully considered in order to mitigate the risk of developing bacterial resistance. Molecular methods including rapid polymerase chain reaction (PCR) diagnostics, 16S sequencing, and/or shotgun and/or targeted whole-genome sequencing are recommended in culture-negative cases of PJI. Expert consultation with an infectious diseases specialist (if available) is recommended to assist with the appropriate antimicrobial management and monitoring of patients with PJI.

Population Pharmacokinetics and Dosing Regimen Optimization of Linezolid in Cerebrospinal Fluid and Plasma of Post-operative Neurosurgical Patients

BackgroundLinezolid is a valuable therapeutic option for infections of the central nervous system caused by multi-drug resistant Gram-positive pathogens. Data regarding linezolid pharmacokinetics in cerebrospinal fluid from post-operative neurosurgical patients have revealed wide inter-individual variability. The objectives of this study were to establish a population pharmacokinetic model for linezolid in plasma and cerebrospinal fluid, as well as to optimize dosing strategies in this susceptible population. MethodsThis was a prospective pharmacokinetic study in post-operative neurosurgical patients receiving intravenous linezolid. Parallel blood and cerebrospinal fluid samples were collected and analyzed. The population pharmacokinetic modelling and Monte Carlo simulations were performed using the Phoenix NLME software. ResultsA two-compartment model (central plasma and cerebrospinal fluid compartments) fit the linezolid data well, with creatinine clearance and serum procalcitonin as significant variables. Linezolid demonstrated highly variable penetration into cerebrospinal fluid, with a mean cerebrospinal fluid/plasma ratio of 0.53. A strong correlation was found between plasma trough concentration and cerebrospinal fluid exposure of linezolid. Based on simulation results, optimal dosage regimens stratified by various renal functions and inflammatory status were proposed. ConclusionA modeling and simulating strategy was employed in dose individualization to improve the efficacy and safety of linezolid treatment.

Ring-fused 2-pyridones effective against multidrug-resistant Gram-positive pathogens and synergistic with standard-of-care antibiotics

The alarming rise of multidrug-resistant Gram-positive bacteria has precipitated a healthcare crisis, necessitating the development of new antimicrobial therapies. Here we describe a new class of antibiotics based on a ring-fused 2-pyridone backbone, which are active against vancomycin-resistant enterococci (VRE), a serious threat as classified by the Centers for Disease Control and Prevention, and other multidrug-resistant Gram-positive bacteria. Ring-fused 2-pyridone antibiotics have bacteriostatic activity against actively dividing exponential phase enterococcal cells and bactericidal activity against nondividing stationary phase enterococcal cells. The molecular mechanism of drug-induced killing of stationary phase cells mimics aspects of fratricide observed in enterococcal biofilms, where both are mediated by the Atn autolysin and the GelE protease. In addition, combinations of sublethal concentrations of ring-fused 2-pyridones and standard-of-care antibiotics, such as vancomycin, were found to synergize to kill clinical strains of VRE. Furthermore, a broad range of antibiotic resistant Gram-positive pathogens, including those responsible for the increasing incidence of antibiotic resistant healthcare-associated infections, are susceptible to this new class of 2-pyridone antibiotics. Given the broad antibacterial activities of ring-fused 2-pyridone compounds against Gram-positive (GmP) bacteria we term these compounds GmPcides, which hold promise in combating the rising tide of antibiotic resistant Gram-positive pathogens.

A Lysozyme Murein Hydrolase with Broad-Spectrum Antibacterial Activity from Enterobacter Phage myPSH1140.

ABSTRACTBacteriophages and bacteriophage-derived peptidoglycan hydrolases (endolysins) present promising alternatives for the treatment of infections caused by multidrug resistant Gram-negative and Gram-positive pathogens. In this study, Gp105, a putative lysozyme murein hydrolase from Enterobacter phage myPSH1140 was characterized in silico, in vitro as well as in vivo using the purified protein. Gp105 contains a T4-type lysozyme-like domain (IPR001165) and belongs to Glycoside hydrolase family 24 (IPR002196). The putative endolysin indeed had strong antibacterial activity against Gram-negative pathogens, including E. cloacae, K. pneumoniae, P. aeruginosa, S. marcescens, Citrobacter sp., and A. baumannii. Also, an in vitro peptidoglycan hydrolysis assay showed strong activity against purified peptidoglycans. This study demonstrates the potential of Gp105 to be used as an antibacterial protein to combat Gram-negative pathogens.

Філогенія білків-експортерів глікопептидних і деяких споріднених антибіотиків

Glycopeptide antibiotics (GPAs) represent one of the most important classes of natural antibiotics coming from actinomycetes – high GC soil-dwelling Gram-positive bacteria. Among GPAs are important clinical compounds, such as vancomycin and teicoplanin, being “last defense line” against multidrug resistant Gram-positive pathogens. Recent works de­monstrated, that peptide antibiotics like ramoplanin and feglymycin, although having rather distinct structure, are genetically related to GPAs. Biosynthesis of all these compounds is coded within large gene assemblages – biosynthetic gene cluster (BGCs). BGCs of GPAs, ramoplanin, feglymycin and other related peptide antibiotics share multiple common features. One of them is the presence of genes coding for ABC-transporters. Most obvious role of these ABC-transporters is export of antibiotics. However, certain role of ABC-transporters in the auto-resistance cannot be excluded as well. Multiple genomes of actinomycetes were sequenced and are fully available today, allowing to build a significant collection of BGCs for GPAs and related peptide antibiotics. Therefore, in this work we aimed to investigate in silico distribution, structural features and phylogeny of ABC-transporters, encoded within 102 BGC of GPAs and related peptide antibiotics. We found out, that ABC-transporters from GPA BGCs are very similar to ABC-transporters from ramoplanin and feglymycin BGCs, as well as to ABC-transporters coded within BGCs of putative compounds. All these proteins belonged to MdlB(MsbA)-like ABC-transporters, possessing N-terminal transmembrane domain with 6 α-helices. Phylogenetic reconstruction revealed that these ABC-transporters fall into several clades, which might be correlated with specific types of peptide antibiotics. Finally, a wider phylogenetic reconstruction allowed to conclude the monophyly of ABC-transporters, encoded within BGCs of GPAs and other related peptide antibiotics.

Tigecycline. Prospects of its application in the fight against polyresistant strains

Despite the advances in antimicrobial therapy, infectious diseases remain one of the leading causes of death worldwide. In most cases, negative results of treatment of bacterial infections are associated with the emergence of pathogens that are resistant to the used antibacterial agents. This whole situation is complicated by the fact that the issue of strain resistance to antibiotics is now becoming more and more threatening. The rate of resistance spread is far outstripping the development of new antimicrobials. For instance, the reports of carbapenem resistance in strains of Klebsiella pneumoniae and other enterobacteria, as well as the rapid spread of carbapenemases among non-fermenting gram-negative bacteria (NFGB), are alarming. The only approved antimicrobial with activity against resistant gram-positive and gram-negative pathogens is tigecycline, the first and only representative of a new class of antibiotics, glycylcyclines. Tigecycline, under the trade name Tygacil® (Wyeth Pharmaceuticals Inc.), was registered in the Russian Federation in October 2009.

Regio‐ and Stereoselective Epoxidation and Acidic Epoxide Opening of Antibacterial and Antiplasmodial Chlorotonils Yield Highly Potent Derivatives

The rise of antimicrobial resistance poses a severe threat to public health. The natural product chlorotonil was identified as a new antibiotic targeting multidrug resistant Gram‐positive pathogens and Plasmodium falciparum. Although chlorotonil shows promising activities, the scaffold is highly lipophilic and displays potential biological instabilities. Therefore, we strived towards improving its pharmaceutical properties by semisynthesis. We demonstrated stereoselective epoxidation of chlorotonils and epoxide ring opening in moderate to good yields providing derivatives with significantly enhanced solubility. Furthermore, in vivo stability of the derivatives was improved while retaining their nanomolar activity against critical human pathogens (e.g. methicillin‐resistant Staphylococcus aureus and P. falciparum). Intriguingly, we showed further superb activity for the frontrunner molecule in a mouse model of S. aureus infection.

Characterization, cytotoxicity, and genotoxicity properties of novel biomediated nanosized-silver by Egyptian Streptomyces roseolus for safe antimicrobial applications

Multi-drug resistant bacteria are not effectively managed with current treatments, making it a serious global problem. Therefore, there is an essential need for finding new antimicrobial agents. In this regard, silver nanoparticles (Ag-NPs) have been projected as a new generation of antimicrobial agents. Ag-NPs were biomediated by Egyptian Streptomyces roseolus for the first time, which was molecularly identified using 16S rRNA sequencing under accession no. MT071505. Biosynthesized Ag-NPs were characterized using UV–Vis spectroscopy, XRD, TEM, FTIR, and DLS. FTIR analysis confirmed the presence of different bioactive functional groups, such as N–H, C–H, C–O–C, C–NH2, and C=O acting as bioreducing/stabilizing agents for Ag-NPs. Ag-NPs exhibited antimicrobial activity against some multi-drug resistant Gram-positive and Gram-negative pathogens. MBC of Ag-NPs against Listeria monocytogenes and Klebsiella pneumonia were 0.195 and 0.048 mg/mL, respectively, with a tolerance level of 2 confirming its biocidal effect. SEM imaging of Ag-NPs-treated L. monocytogenes and K. pneumonia showed shrunk destroyed cells after 6 h of treatment. Biosynthesized Ag-NPs exhibited IC50 of < 0.3 and 8.21 mg/mL, on normal Human Skin Fibroblast, and Blood Lymphocytes, respectively. IC50 values were significantly higher than its MBC values, with no harmful cytotoxic effect, thus can be safely applied at its biocidal concentration. For biosafety purposes, the genotoxicity of biosynthesized Ag-NPs was assessed using Comet assay for the first time on Blood Lymphocytes, with zero-tail and 100% head intensity indicating non-genotoxic effect. An ecofriendly biomediated synthesis of Ag-NPs was described with easy scale-up, non-toxic by-products, so, it can be recommended as a powerful-safe antimicrobial agent.Graphical abstract

Efflux-Mediated bile Resistance in Gram-Positive Pathogens

Gram-positive pathogens are causing many serious infections that affect humans and result in mild to severe diseases worldwide. In order to survive and initiate infection, enteric pathogens must resist the physiochemical defence factors in the human intestinal tract. One of these defence factors is bile, a potent antibacterial like compound in the intestine. Efflux pumps are the important mechanism by which bacteria resist antibacterial agents such as bile. Efflux of antimicrobial substances outside the bacterial cell is considered as a key factor for intestinal colonization and virulence of enteric pathogens. This paper will review the research conducted on efflux–mediated bile resistance in Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis and Clostridium perfringens. These bacteria colonize in the human &amp; animal gastrointestinal tract and they have a multiple mechanism to resist the innate defences in the gut and antibacterial activity of bile. However, bile resistance in these bacteria is not fully understood. The evidence from this review suggests that Gram-positive pathogens have the ability to active transport of bile. Further research is needed to know how these pathogens sense bile and how bile regulates its virulence factor. In general, therefore, it seems that understanding the specific mechanism of bile resistance in enteric bacteria including gram-positive pathogens may involve in the development of novel strategies to control and treatment of gastrointestinal infections.

Prescription-Event Monitoring Study on Safety and Efficacy of Levonadifloxacin (Oral and I.V.) in Management of Bacterial Infections: Findings of Real-World Observational Study.

Background:Levonadifloxacin is a novel broad-spectrum antibiotic belonging to the benzoquinolizine subclass of quinolones. It is available in intravenous as well as oral formulation for the treatment of infections caused by common Gram-positive bacterial pathogens including methicillin-resistant Staphylococcus aureus (MRSA).Patients and Methods:This study retrospectively assessed the real-world safety and efficacy of levonadifloxacin (oral and/or IV) in the treatment of 1229 patients across various clinical conditions. Study outcomes were clinical and microbiological success at the end of therapy.Results:The mean duration of levonadifloxacin therapy was 7.2 days, with a time to clinical improvement averaging at 4 days. Three hundred and three patients received oral therapy, 875 received IV, and 51 received a combination of IV followed by oral therapy. Patients were prescribed levonadifloxacin for skin and soft-tissue infections, diabetic foot infections, septicemia, catheter-related bloodstream infections, bone and joint infections, febrile neutropenia, and respiratory infections including COVID-19 pneumonia. High clinical success rates of 98.3%, 93.7%, and 96.1% with oral, IV, and IV followed by oral levonadifloxacin, respectively, were obtained. Only 11 mild adverse events were reported in 9 patients which included constipation, diarrhea, hyperglycemia, nausea, fatigue, and vomiting. Overall, 96.3% and 97.3% of investigators rated the efficacy and safety of levonadifloxacin as “good to excellent.”Conclusions:An excellent safety and efficacy profile of levonadifloxacin was observed in this study making it a suitable treatment option for management of various bacterial infections, including those caused by resistant Gram-positive pathogens such as MRSA and quinolone-resistant S. aureus.

Glycopeptide antibiotic discovery in the genomic era.

Glycopeptide antibiotics are essential drugs used to treat infections caused by multi-drug resistant Gram-positive pathogens. There is a continuous need for new antibiotics, including GPAs, to address emerging resistance and offer desirable pharmacological profiles for improved efficacy. Microbial natural products are proven sources of antibiotics, and this source has dominated drug discovery over the past century. Bacteria from the phylum Actinobacteria are particularly renowned for producing a diverse range of bioactive natural products including glycopeptide antibiotics. The traditional approach to mining this resource is through the culture and extraction of natural products followed by assay for cell-killing activity. Unfortunately, this method no longer efficiently yields new antibiotic leads, delivering instead known compounds. Whole-genome sequencing programs on the other hand are revealing thousands of unexplored natural product biosynthetic gene clusters in the chromosomes of Actinobacteria. These gene clusters encode the necessary enzymes, transport and resistance mechanisms, along with regulatory elements for the biosynthesis of a variety of antibiotics. Identification of uncharacterized or cryptic biosynthetic gene clusters to unlock the chemical "dark matter" represents a new direction for the discovery of new drug candidates. This chapter discusses the identification of glycopeptide antibiotic biosynthetic gene clusters in microbial genomes, the improved production of these antibiotics using the GPAHex synthetic biology platform, and methods for their purification.

1,2,3-Triazole-gold(I)-triethylposphine derivatives active against resistant Gram-positive pathogens

Innovative organogold(I) antibacterial compounds were synthesized by click chemistry with triethylphosphine-gold(I) azides and an alkyne derivative. The resulting organo-gold(I) compounds exhibit high levels of antibacterial activity against Gram-positive pathogens, with particularly low MICs against Clostridium difficile.

Prevalence of antibiotic-resistant organisms among hospitalized patients at a tertiary care center in Lebanon, 2010–2018

BackgroundInfections due to antibiotic resistant organisms (ARO) among hospitalized patients are associated with increased morbidity, mortality, and healthcare costs. Longitudinal data about antimicrobial resistance are scarce in Lebanon and the region. The objective of this study is to describe the temporal trends of resistance of selected pathogens among hospitalized patients at a tertiary care center in Lebanon. MethodsWe conducted a retrospective review of surveillance data from 2010 until 2018. Six target organisms isolated from hospitalized patients were included: carbapenem-resistant Escherichia coli (CREC), carbapenem-resistant Klebsiella spp. (CRKP), multi-drug resistant Pseudomonas aeruginosa (MDRPA), carbapenem-resistant Acinetobacter baumannii (CRAB), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus spp. (VRE). Correlation analysis was performed to evaluate for temporal trends. ResultsA total of 15,901 isolates were examined, most of which were obtained from urinary specimens. Among Gram-negative organisms, the highest resistance was found among CRAB (81.7%), followed by CRKP (6.5%) and CREC (3.3%). MDRPA overall prevalence was 0.8%. Among Gram-positive organisms, the prevalence of MRSA and VRE was 26.2% and 2.6%, respectively. CREC, MRSA, and VRE showed statistically significant increasing temporal trends, while CRAB decreased significantly from 2013 to 2018. ConclusionThese data are helpful in characterizing the epidemiology of antimicrobial resistance in Lebanon and show that controlling emerging resistance is achievable with concerted infection control and antimicrobial stewardship efforts. Caution should be exercised to contain early on the spread of CREC and of resistant Gram-positive pathogens.

Antimicrobial Sensitivity Pattern of Isolates from Neonatal Sepsis in Yekatit 12 Teaching Hospital, Addis Ababa, Ethiopia

Sepsis is one of the commonest reasons of neonatal deaths. It is accountable for about 30 - 50% of the whole baby deaths in the developing ountries. The current study aimed to assess drug susceptibility patterns of isolates from cases of neonatal sepsis. Institution based cross-sectional study was conducted among 132 neonates admitted to Yekatit 12 teaching hospital with the diagnosis of sepsis and who had a positive result for culture and sensitivity test. Data was collected through medical chart review using data abstraction tool. The data was analyzed using excel and reported using descriptive tables. Gram-negative bacteria were the commonest organisms identified 124 (93.9%), followed by gram-positive isolates (6.1%). Klebsiella (87.9%) was the predominant gram-negative bacteria. Of the gram-positive organisms, coagulase negative staphylococci (3.03%) were the commonest pathogen, followed by Staphylococcus aureus (2.27%). Among the gram-negative isolates, overall sensitivity was high to meropenem (96.0%), amikacin (94.3%) and amoxicillin + clavulanate (74.2%) but sensitivity was very low to ampicillin (2.7%), and amoxicillin (7.3%).Generally, the isolated pathogens were resistant to commonly used antibiotics in the study setting and resistance of gram-positive pathogens Against penicillins and cephalosporins was also high. Hence, rational and tailored antibiotic use based on the susceptibility data is recommended and regular antibiotic susceptibility surveillance should be conducted.&#x0D; Keywords: neonatal sepsis, cross-sectional study, antibiotics, culture, sensitivity, resistance

Improved A40926 production from Nonomuraea gerenzanensis using the promoter engineering and the co-expression of crucial genes

The semi-synthetic antibiotic dalbavancin is clinically used in the treatment of severe infections caused by multidrug resistant Gram-positive pathogens. So far, fermentation has still been the only approach for the production of A40926 in the industrial scale, which is used as the precursor of dalbavancin and biosynthesized by the rare actinomycete Nonomuraea gerenzanensis (N. gerenzanensis). Therefore, it is particularly essential and necessary to enhance the yield of A40926 continually. In this paper, we firstly assessed the activity of 6 heterologous promoters using the enhanced green fluorescence protein (EGFP) reporter system in N. gerenzanensis. Furthermore, the strongest constitutive promoter gapdh confirmed in this study was applied to separately overexpress the total of ten dbv genes involved in the A40926 biosynthesis. PCR and RT-qPCR were successively carried out to verify the mutant and the overexpression of dbv genes. As a consequence, the overexpression of dbv3 and dbv20 genes both increased the A40926 production remarkably. Based on the above consequences, a mutant strain named N320 laboring the co-expression of dbv3 and dbv20 was constructed. The results of fermentation showed that the N320 strain enhanced the yield of A40926 from 163 mg/L to 272 mg/L.