Gram-negative Bacterial Species Research Articles

Bacterial Pathogens and Their Antimicrobial Resistance Patterns of Inanimate Surfaces and Equipment in Ethiopia: A Systematic Review and Meta-analysis.

Background Hospital-acquired infections have remained a serious cause of mortality, morbidity, and extended hospitalization. Bacterial contamination of inanimate surfaces of the hospital environment and equipment is considered a major contributing factor to the development of several nosocomial infections worldwide. The hospital environment and many devices are an important reservoir of many clinically important bacterial agents including multidrug-resistant pathogens. Therefore, this systematic review and meta-analysis are aimed at investigating bacterial pathogens and their antimicrobial resistance patterns of inanimate surfaces and equipment in Ethiopia. Methods An exhaustive literature search was carried out using the major electronic databases including PubMed, Web of Science, MEDLINE, EMBASE, CINAHL, Google Scholar, Cochrane Library, Scopus, and Wiley online library to identify potentially relevant studies without date restriction. Original articles which address the research question were identified, screened, and included using the PRISMA flow diagram. Data extraction was prepared in Microsoft Excel, and data quality was assessed by using 9-point Joanna Briggs Institute critical appraisal tools. Then, data were exported to STATA 16.0 software for analyses of pooled estimation of outcome measures. Estimation of outcome measures at a 95% confidence interval was performed using DerSimonian-Laird's random-effects model. Finally, results were presented via text, figures, and tables. Results A total of 18 studies with 3058 bacterial isolates recovered from 3423 swab specimens were included for systematic review and meta-analysis. The pooled prevalence of bacterial contamination of inanimate surfaces and equipment was found 70% (95% CI: 59, 82). Among the Gram-negative bacterial species, the prevalence of ampicillin-resistant K. pneumoniae was the highest 80% (95% CI: 78, 92) followed by Citrobacter species 78% (95% CI: 57, 83). Conclusion This study has shown a high prevalence of bacterial contamination of inanimate surfaces and equipment in Ethiopia.

Bacterial isolates and their antibiotic sensitivity pattern of surgical site infections among the surgical ward patients of Asella Referral and Teaching Hospital

BackgroundSurgical site infection (SSI) is the most typical problem for patients who undergo operative procedures. It remains a typical and widespread problem causing morbidity and mortality, partly related to a rise in infections due to antimicrobial-resistant bacterial pathogens. The study was purposed to evaluate the bacterial isolates and their drug susceptibility patterns in patients with postoperative surgical site infection.ResultsThe rate of postoperative surgical site infections was studied at Asella Referral and Teaching Hospital and found to be 23.3%. One hundred fifty specimens of pus and surface swabs were collected from the surgical site-infected patients over the period of March 2016 to May 2017, and from that, a total of 147 bacterial pathogens were recovered. The predominant organisms associated with postoperative surgical site infections were Klebsiella species 38 (26%, n=147), Escherichia coli 31 (21%, n=147), Staphylococcus aureus 25 (17%, n=147), and Pseudomonas aeruginosa 18 (12%, n=147).ConclusionHigher number of bacterial isolates were recovered. The predominant isolates were Klebsiella species, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The majority of gram-negative bacterial species which were isolated were found to be resistant to the commonly prescribed antimicrobial agents in the study setting. Thus, to achieve effective therapy for wound infections and to reduce/stop the appearance of multidrug-resistant (MDR) pathogens, continuous monitoring is essential with the fair use of antimicrobial agents.

Molecular Simplification of Natural Products: Synthesis, Antibacterial Activity, and Molecular Docking Studies of Berberine Open Models.

Berberine, the main bioactive component of many medicinal plants belonging to various genera such as Berberis, Coptis, and Hydrastis is a multifunctional compound. Among the numerous interesting biological properties of berberine is broad antimicrobial activity including a range of Gram-positive and Gram-negative bacteria. With the aim of identifying berberine analogues possibly endowed with higher lead-likeness and easier synthetic access, the molecular simplification approach was applied to the secondary metabolite and a series of analogues were prepared and screened for their antimicrobial activity against Gram-positive and Gram-negative bacterial test species. Rewardingly, the berberine simplified analogues displayed 2–20-fold higher potency with respect to berberine. Since our berberine simplified analogues may be easily synthesized and are characterized by lower molecular weight than the parent compound, they are further functionalizable and should be more suitable for oral administration. Molecular docking simulations suggested FtsZ, a well-known protein involved in bacterial cell division, as a possible target.

Ecotin and LamB in Escherichia coli influence the susceptibility to Type VI secretion-mediated interbacterial competition and killing by Vibrio cholerae

BackgroundA prevailing action of the Type VI secretion system (T6SS) in several Gram-negative bacterial species is inter-bacterial competition. In the past several years, many effectors of T6SS were identified in different bacterial species and their involvement in inter-bacterial interactions were described. However, possible defence mechanisms against T6SS attack among prey bacteria were not well clarified yet. MethodsEscherichia coli was assessed for susceptibility to T6SS-mediated killing by Vibrio cholerae. TheT6SS-mediated bacterial killing assays were performed in absence or presence of different protease inhibitors and with different mutant E. coli strains. Expression levels of selected proteins were monitored using SDS-PAGE and immunoblot analyses. ResultsThe T6SS-mediated killing of E. coli by V. cholerae was partly blocked when the serine protease inhibitor Pefabloc was present. E. coli lacking the periplasmic protease inhibitor Ecotin showed enhanced susceptibility to killing by V. cholerae. Mutations affecting E. coli membrane stability also caused increased susceptibility to killing by V. cholerae. E. coli lacking the maltodextrin porin protein LamB showed reduced susceptibility to killing by V. cholerae whereas E. coli with induced high levels of LamB showed reduced survival in inter-bacterial competition. ConclusionsOur study identified two proteins in E. coli, the intrinsic protease inhibitor Ecotin and the outer membrane porin LamB, that influenced E. coli susceptibility to T6SS-mediated killing by V. cholerae. General significanceWe envision that it is feasible to explore these findings to target and modulate their expression to obtain desired changes in inter-bacterial competition in vivo, e.g. in the gastrointestinal microbiome.

Drug screening to identify compounds to act as co-therapies for the treatment of Burkholderia species.

Burkholderia pseudomallei is a soil-dwelling organism present throughout the tropics. It is the causative agent of melioidosis, a disease that is believed to kill 89,000 people per year. It is naturally resistant to many antibiotics, requiring at least two weeks of intravenous treatment with ceftazidime, imipenem or meropenem followed by 6 months of orally delivered co-trimoxazole. This places a large treatment burden on the predominantly middle-income nations where the majority of disease occurs. We have established a high-throughput assay for compounds that could be used as a co-therapy to potentiate the effect of ceftazidime, using the related non-pathogenic bacterium Burkholderia thailandensis as a surrogate. Optimization of the assay gave a Z' factor of 0.68. We screened a library of 61,250 compounds and identified 29 compounds with a pIC50 (-log10(IC50)) greater than five. Detailed investigation allowed us to down select to six "best in class" compounds, which included the licensed drug chloroxine. Co-treatment of B. thailandensis with ceftazidime and chloroxine reduced culturable cell numbers by two orders of magnitude over 48 hours, compared to treatment with ceftazidime alone. Hit expansion around chloroxine was performed using commercially available compounds. Minor modifications to the structure abolished activity, suggesting that chloroxine likely acts against a specific target. Finally, an initial study demonstrates the utility of chloroxine to act as a co-therapy to potentiate the effect of ceftazidime against B. pseudomallei. This approach successfully identified potential co-therapies for a recalcitrant Gram-negative bacterial species. Our assay could be used more widely to aid in chemotherapy to treat infections caused by these bacteria.

Effective Small Molecule Antibacterials from a Novel Anti-Protein Secretion Screen.

The increasing problem of bacterial resistance to antibiotics underscores the urgent need for new antibacterials. Protein export pathways are attractive potential targets. The Sec pathway is essential for bacterial viability and includes components that are absent from eukaryotes. Here, we used a new high-throughput in vivo screen based on the secretion and activity of alkaline phosphatase (PhoA), a Sec-dependent secreted enzyme that becomes active in the periplasm. The assay was optimized for a luminescence-based substrate and was used to screen a ~240K small molecule compound library. After hit confirmation and analoging, 14 HTS secretion inhibitors (HSI), belonging to eight structural classes, were identified with IC50 < 60 µM. The inhibitors were evaluated as antibacterials against 19 Gram-negative and Gram-positive bacterial species (including those from the WHO’s top pathogens list). Seven of them—HSI#6, 9; HSI#1, 5, 10; and HSI#12, 14—representing three structural families, were bacteriocidal. HSI#6 was the most potent hit against 13 species of both Gram-negative and Gram-positive bacteria with IC50 of 0.4 to 8.7 μM. HSI#1, 5, 9 and 10 inhibited the viability of Gram-positive bacteria with IC50 ~6.9–77.8 μM. HSI#9, 12, and 14 inhibited the viability of E. coli strains with IC50 < 65 μM. Moreover, HSI#1, 5 and 10 inhibited the viability of an E. coli strain missing TolC to improve permeability with IC50 4 to 14 μM, indicating their inability to penetrate the outer membrane. The antimicrobial activity was not related to the inhibition of the SecA component of the translocase in vitro, and hence, HSI molecules may target new unknown components that directly or indirectly affect protein secretion. The results provided proof of the principle that the new broad HTS approach can yield attractive nanomolar inhibitors that have potential as new starting compounds for optimization to derive potential antibiotics.

Isolation and Characterization of Gram-Negative Bacterial Species from Pasteurized Dairy Products: Potential Risk to Consumer Health

Pathogenic bacterial contaminants of dairy products cause economic and human life losses if not destroyed by pasteurization. Gram-negative bacteria are among such major contaminants. Contamination persists because of faulty pasteurization or occurs during postpasteurization processing. Many factors, including presence of asymptomatic healthy carriers, existence of broad-range host pathogens, and resistance of pathogens to ordinary disinfectants, hamper the control of such pathogens. Here, samples of pasteurized dairy products were subjected to enrichment/selective cultures to test for possible Salmonella contamination, followed by growth on/in various media to test for phenotypic properties and some virulence characteristics of isolates (catalase, urease, oxidase, gelatinase, etc.). Isolates were characterized by phenotypic and genotypic tests for identification and resistance to clinically relevant antibiotics, including disk diffusion and for β-lactamase production. All milk samples harbored Gram-negative bacilli, which constitute a public health hazard. All of the isolates exhibited intermediate-level or higher resistance to ≥2 clinically relevant antibiotics, while some were susceptible. None tested positive for phenotypic gelatin hydrolysis but exhibited alpha- or beta-hemolysis. Sequence alignments of 16S rRNA gene partial sequences suggested up to 99% sequence similarities to subspecies of Salmonella enterica. Most isolates were also β-lactamase producers, especially blaTEM. In conclusion, high contamination rates were found in all Ethiopian pasteurized milk samples. The reasons for this burden of contamination need to be elucidated for meaningful and targeted control. Larger studies are needed, specifically to reveal points of entry of potential pathogens into dairy products. Information from this work will help to address and control previously unrecognized health hazards associated with consumption of pasteurized dairy products.

Chemical Highlights Supporting the Role of Lipid A in Efficient Biological Adaptation of Gram-Negative Bacteria to External Stresses.

The outer membrane (OM) of Gram-negative bacteria provides an efficient barrier against external noxious compounds such as antimicrobial agents. Associated with drug target modification, it contributes to the overall failure of chemotherapy. In the complex OM architecture, Lipid A plays an essential role by anchoring the lipopolysaccharide in the membrane and ensuring the spatial organization between lipids, proteins, and sugars. Currently, the targets of almost all antibiotics are intracellularly located and require translocation across membranes. We report herein an integrated view of Lipid A synthesis, membrane assembly, a structure comparison at the molecular structure level of numerous Gram-negative bacterial species, as well as its recent use as a target for original antibacterial molecules. This review paves the way for a new vision of a key membrane component that acts during bacterial adaptation to environmental stresses and for the development of new weapons against microbial resistance to usual antibiotics.

A Secreted NlpC/P60 Endopeptidase from Photobacterium damselae subsp. piscicida Cleaves the Peptidoglycan of Potentially Competing Bacteria.

Peptidoglycan (PG) is a major component of the bacterial cell wall, forming a mesh-like structure enwrapping the bacteria that is essential for maintaining structural integrity and providing support for anchoring other components of the cell envelope. PG biogenesis is highly dynamic and requires multiple enzymes, including several hydrolases that cleave glycosidic or amide bonds in the PG. This work describes the structural and functional characterization of an NlpC/P60-containing peptidase from Photobacterium damselae subsp. piscicida (Phdp), a Gram-negative bacterium that causes high mortality of warm-water marine fish with great impact for the aquaculture industry. PnpA ( PhotobacteriumNlpC-like protein A) has a four-domain structure with a hydrophobic and narrow access to the catalytic center and specificity for the γ-d-glutamyl-meso-diaminopimelic acid bond. However, PnpA does not cleave the PG of Phdp or PG of several Gram-negative and Gram-positive bacterial species. Interestingly, it is secreted by the Phdp type II secretion system and degrades the PG of Vibrio anguillarum and Vibrio vulnificus This suggests that PnpA is used by Phdp to gain an advantage over bacteria that compete for the same resources or to obtain nutrients in nutrient-scarce environments. Comparison of the muropeptide composition of PG susceptible and resistant to the catalytic activity of PnpA showed that the global content of muropeptides is similar, suggesting that susceptibility to PnpA is determined by the three-dimensional organization of the muropeptides in the PG.IMPORTANCE Peptidoglycan (PG) is a major component of the bacterial cell wall formed by long chains of two alternating sugars interconnected by short peptides, generating a mesh-like structure that enwraps the bacterial cell. Although PG provides structural integrity and support for anchoring other components of the cell envelope, it is constantly being remodeled through the action of specific enzymes that cleave or join its components. Here, it is shown that Photobacterium damselae subsp. piscicida, a bacterium that causes high mortality in warm-water marine fish, produces PnpA, an enzyme that is secreted into the environment and is able to cleave the PG of potentially competing bacteria, either to gain a competitive advantage and/or to obtain nutrients. The specificity of PnpA for the PG of some bacteria and its inability to cleave others may be explained by differences in the structure of the PG mesh and not by different muropeptide composition.

Synthesis, Characterization, Single-Crystal X-ray Structure and Biological Activities of [(Z)-N′-(4-Methoxybenzylidene)benzohydrazide–Nickel(II)] Complex

(Z)-N′-(4-methoxybenzylidene)benzohydrazide (HL) and its Ni(II) complex (Ni(II)-2L) were synthesized using eco-friendly protocols. The single X-ray crystal structure of Ni(II)-2L was solved. Moreover, the structural properties were evaluated using Fourier transform infrared, proton nuclear magnetic resonance, mass, and Ultraviolet/Visible spectroscopy. The diamagnetic and thermal stability were assessed using magnetic susceptibility and thermogravimetric analysis, respectively. The biological activities of both HL and Ni(II)-2L (62.5–1000 μg/mL) against Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial and fungal (Candida albicans, Aspergillus niger, and Aspergillus clavatus) species were studied using the minimum inhibitory concentration (MIC) tests method in reference to Gentamycin and Nystatin standard drugs, respectively. The results revealed an affordable, environmentally friendly, and efficient synthetic method of HL using water as a green solvent. The Ni(II)-2L complex crystallized in a distorted square planar, P21/n space group, and one Ni(II) to two bidentate negatively charged ligand ratio. The analysis of biological activity revealed higher activity of the complex against S. aureus and S. pyogenes (bacteria) and A. niger and A. clavatus (fungi) compared to the ligand. However, the highest activity was at a MIC of 62.5 μg/mL for the complex against S. pyogenes and for the ligand against E. coli. Therefore, both HL and Ni(II)-2L could be promising potential antimicrobials and their selective activity could be an additional benefit of these bioactive materials.

Microwave-Assisted Synthesis, Structural Characterization and Assessment of the Antibacterial Activity of Some New Aminopyridine, Pyrrolidine, Piperidine and Morpholine Acetamides.

A series of new acetamide derivatives 22–28 of primary and secondary amines and para-toluene sulphinate sodium salt have been synthesized under microwave irradiation and assessed in vitro for their antibacterial activity against one Gram-positive and two Gram-negative bacterial species such as S. pyogenes, E. coli, and P. mirabilis using the Mueller-Hinton Agar diffusion (well diffusion) method. The synthesized compounds with significant differences in inhibition diameters and MICs were compared with those of amoxicillin, ampicillin, cephalothin, azithromycin and doxycycline. All of the evaluated acetamide derivatives were used with varying inhibition concentrations of 6.25, 12.5, 37.5, 62.5, 87.5, 112.5 and 125 µg/mL. The results show that the most important antibacterial properties were displayed by the synthetic compounds 22 and 24, both of bear a para-chlorophenyl moiety incorporated into the 2-position moiety of acetamide 1. The molecular structures of the new compounds were determined using the FT-IR and 1H-NMR techniques.

T6SS Mediated Stress Responses for Bacterial Environmental Survival and Host Adaptation

The bacterial type VI secretion system (T6SS) is a protein secretion apparatus widely distributed in Gram-negative bacterial species. Many bacterial pathogens employ T6SS to compete with the host and to coordinate the invasion process. The T6SS apparatus consists of a membrane complex and an inner tail tube-like structure that is surrounded by a contractile sheath and capped with a spike complex. A series of antibacterial or antieukaryotic effectors is delivered by the puncturing device consisting of a Hcp tube decorated by the VgrG/PAAR complex into the target following the contraction of the TssB/C sheath, which often leads to damage and death of the competitor and/or host cells. As a tool for protein secretion and interspecies interactions, T6SS can be triggered by many different mechanisms to respond to various physiological conditions. This review summarizes our current knowledge of T6SS in coordinating bacterial stress responses against the unfavorable environmental and host conditions.

Synthesis and Docking Studies of Novel Carbazole-Thiazolidinedione Hybrid Derivatives as Antibacterial Agents

A series of novel carbazol-thiazolidinedione hybrid derivatives were designed, synthesised and screened for antimicrobial activity against gram-positive and gram-negative bacterial species. All the novel compounds were characterized by 1H, 13C NMR, IR, and Mass spectral analysis data. The results of antibacterial study indicated that compounds (Vc) and (Vh) showed appreciable antibacterial activity. Furthermore, molecular docking of selected compounds was also performed to see interaction between active compound and binding site.

Synthesis, crystal structure and biological application of a Cu(II) coordination compound of 2-hydroxy-5-methyl-3-(pyridin-3-yliminomethyl)-benzaldehyde

A Cu(II) compound, [Cu(L)2] (1) [HL = 2-Hydroxy-5-methyl-3-(pyridin-3-yliminomethyl)-benzaldehyde] has been characterized by single-crystal X-ray diffraction technique and other spectroscopic data. Presence of different noncovalent interactions leads to 3D supramolecular structure. Hirshfeld surfaces analysis is performed to investigate the extent of non-covalent interactions in the solid state. Compound 1 exhibits potential antibacterial activity against Gram-positive (S. aureus) and Gram-negative (E. coli) bacterial species. The measurement of ROS generation may also help to explain the mechanism of microbial action which may be due to one or multiple steps of signaling cascades ensuing in damaged cell wall synthesis or impaired cross-linking of polymer units. Furthermore, the compound improves cellular ROS in human liver cancer cells which in turn culminates in the death of cancer cells. The toxicity has been checked by MTT assay. The compound shows promising anticancer activity against HepG2 cell line and the LD50 is 62 μg/ml. The compound can also be employed for promising material applications; after theoretical and experimental investigations it is observed that the band gap is in the range of semiconducting material.

Growth and morphologic response of rumen methanogenic archaea and bacteria to cashew nut shell liquid and its alkylphenol components.

The growth and morphology of rumen methanogenic archaea (15 strains of 10 species in 5 genera, including 7 strains newly isolated in the present study) and bacteria (14 species in 12 genera) were investigated using unsupplemented in vitro pure cultures and cultures supplemented with cashew nut shell liquid (CNSL) and its phenolic compound components, anti-methanogenic agents for ruminant animals. Growth of most of the methanogens tested was inhibited by CNSL and alkylphenols at different concentrations ranging from 1.56 to 12.5μg/ml. Of the alkylphenols tested, anacardic acid exhibited the most potent growth inhibition. Three gram-negative bacterial species involved in propionate production were resistant to CNSL and alkylphenols (>50 μg/ml). All the methanogens and bacteria that were sensitive to CNSL and alkylphenols exhibited altered morphology; disruption of the cell surface was notable, possibly due to surfactant activity of the tested materials. Cells division was inhibited in some organisms, with cell elongation and unclear septum formation observed. These results indicate that CNSL and alkylphenols, particularly anacardic acid, inhibit both rumen bacteria and methanogens in a selective manner, which could help mitigate rumen methane generation.

152. rapid Ultra-high Enrichment of Bacterial Pathogens at Low Concentration from Blood for Species ID and AMR Prediction Using Nanopore Sequencing

BackgroundEach year in the United States there are over 1.7 million cases of sepsis that account for a third of hospital deaths. A key to reducing morbidity and mortality rates is early, appropriate antibiotic therapy. Most new diagnostic approaches still suffer from insufficient sensitivity to low bacterial loads in blood and limited sets of detection targets for bacterial species identification (ID) and antimicrobial resistance (AMR) determination. As such, blood culture remains the gold standard for diagnosing bacteremia despite limitations such as > 2-day turnaround time (TAT), incompatibility with fastidious organisms, and frequent inability to recover causative pathogens.Methods31 clinically relevant bacterial pathogens, made up of 17 gram-positive and 14 gram-negative bacterial species, were spiked into 2 to 4 healthy donor blood samples at 1 to 5 CFU/mL. The samples were run through our proprietary Blood2Bac™ pipeline, sequenced on a nanopore platform, and data were passed through Keynome®, our proprietary machine learning algorithm to determine species ID and AMR.ResultsBy assessing the efficiency of pathogen DNA enrichment and genome coverage post sequencing, we report high performance of 3 CFU/mL for 3 bacterial species and ≤ 2 CFU/mL for the 28 remaining species, which includes S. aureus, E. coli, and Streptococcus spp., three of the leading causes of sepsis.For all 31 bacterial species tested, Keynome called species ID with 100% accuracy. In addition, Keynome also predicted the AMR profile of pathogens with 100% accuracy for 19 drug/species AMR combinations, including ciprofloxacin for E. coli, clindamycin for S. aureus, and aztreonam for K. pneumoniae.ConclusionBlood2Bac is able to enrich a wide range of bacterial pathogens directly from blood and enable bacterial whole genome sequencing with an estimated TAT of 12 hours. When coupled with Keynome, our process provides accurate species ID and AMR calls for key BSI pathogens even at single-digit CFU/mL concentrations. Our species-agnostic and culture-free process enables detection of a diverse range of bacterial species with high sensitivity, providing a robust and comprehensive diagnostic.DisclosuresChiahao Tsui, n/a, Day Zero Diagnostics (Employee, Shareholder) Lisa S. Cunden, PhD, Day Zero Diagnostics (Shareholder) Nicole Billings, PhD, Day Zero Diagnostics (Employee) Imaly A. Nanayakkara, PhD, Day Zero Diagnostics (Employee, Shareholder) Ian Herriott, BS, Day Zero Diagnostics (Employee, Shareholder) Rachel R. Martin, n/a, Day Zero DIagnostics (Employee) Michelle Chen, MS, Day Zero Diagnostics (Employee, Shareholder) Febriana Pangestu, n/a, Day Zero Diagnostics (Employee, Shareholder) Paul Knysh, PhD, Day Zero Diagnostics (Employee) Cabell Maddux, n/a, Day Zero Diagnostics (Employee, Shareholder) Zachary Munro, n/a, Day Zero Diagnostics Inc. (Employee, Shareholder) Miriam Huntley, PhD, Day Zero Diagnostics (Employee, Shareholder)

Sputum bacterial profile and antibiotics sensitivity pattern in acute exacerbation of chronic obstructive pulmonary disease

ABSTRACT Background: Constant microbiologic screening of patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is vital to control the possible alteration of pathogens, as well as their antibiotic resistance. Objective: to identify sputum bacterial profile and antibiotics sensitivity in patients with AECOPD aiming to adjust antibiotics use and reduce antibiotics resistance. Methodology: This cross-sectional study was conducted on 100 patients with AECOPD. The total and differential leucocytic count, spirometric-indices, sputum gram stain, sputum semi-quantitative culture using colony forming unit (CFU) were done for all patients. Additionally, assessments of the sensitivity of the isolated pathogenic bacterial species were done for 25 antibiotics by disk diffusion method. Results: by sputum semi-quantitative culture 28% of the studied patients have non-pathogenic bacterial growth (i.e., growth of normal flora) and 72% have pathogenic bacterial growth. Amongthose with pathogenic bacterial growth the isolated bacterial species in descending order were klebsiella (40.3%), staphylococcus aureus (19.4%), pseudomonas (12.5%), streptococcal pneumoniae, E. coli (8.3% each), acinetobacter (6.9%), citrobacter (2.8%) and enterobacter (1.4%). The most predictive factors for bacterial etiology in AECOPD in descending orders were decreased blood eosinophils % (B = - 0.16), increased blood neutrophils % (B = 0.04), increased blood lymphocytes (B = 0.02), and lower FEV1% (B = - 0.01). Levofloxacin was the most sensitive antibiotics (91.7%), followed by amikacin (88.9%), ciprofloxacin (87.5%) and gentamycin (87.5%) then imipenem (81.7%) and ofloxacin (76.4%). On the other hand, linezolid and vancomycin were the most resistant antibiotics (95.8% each), followed by clindamycin and cefotaxime (91.7% each) then colistin sulphate and tetracycline (90.3% each). Conclusion: Gram-negative bacterial species especially klebsiella was the most prevalent organism’s in AECOPD. The isolated bacterial species were sensitive mainly to quinolones, gentamycin, amikacin, and imipenem, while it was mainly resistant to clindamycin, cefotaxime, colistin sulphate, tetracycline.

Low temperature preservation: Influence of putative bioactive microalgae and hop extracts on sperm quality and bacterial load in porcine semen

The frequent use of antibiotics in artificial insemination promotes the development of antibiotic resistance. Therefore, alternatives must be considered. In this study, putative bioactive microalgae and hop extracts were examined to estimate their effect on quality and bacterial load of preserved porcine semen when used a low-temperature storage at 5 °C in Androstar® Premium (ASP) extender (Minitüb). Firstly, five algae extracts (Neochloris oleoabundans (NEO), Pseudococcomyxa simplex (PSEY), Phormidium ambiquum (PHA), Schizochlamydella minutissima (SCH), Cyanidioschyzon merolae (CYA)) and one hop extract (Humulus lupulus (HOP)) in four concentrations (0.2, 2, 20 and 200 μg/mL) were tested on their sperm-compatibility at 17 °C. All extracts in the concentrations 0.2 and 2 μg/mL appeared to be sperm compatible. After 72 h of storage at 5 °C, variants showed an increase of total bacterial subcultures from 103 (ASP w/o supplements) to 113/136/135/136/126/118 (ASP w/NEO/PSEY/PHA/HOP/SCH/CYA). Even though bacterial growth was not inhibited in general, all extracts showed an antimicrobial effect on specific bacteria, including Gram-positive (Trueperella pyogenes, Streptococcus porcinus) and Gram-negative bacterial species (Alcaligenes faecalis, Pseudomonas aeruginosa, Ralstonia sp., Pasteurella sp., Proteus sp., Providencia stuartii, and Escherichia coli). While the proportion of these species was 10% in the control (ASP w/o supplements), their proportion in the supplemented variants ranged from 8% (NEO, HOP) to as low as 3% (PSEY). Although the tested extracts are not suitable to replace conventional antibiotics due to their lack of broad-spectrum antimicrobial activity, they nevertheless present promising opportunities for bacteria-specific, customizable usage in boar semen extenders combined with antibiotics or other antimicrobial agents.

Comparison of Agar Dilution to Broth Microdilution for Testing In Vitro Activity of Cefiderocol against Gram-Negative Bacilli.

Cefiderocol (CFDC) is a siderophore cephalosporin with activity against Gram-negative bacterial species that are resistant to carbapenems and other drugs. The MICs of CFDC were determined for 610 Gram-negative bacilli, including 302 multinational Enterobacterales isolates with characterized mechanisms of beta-lactam resistance, 180 clinical isolates from the Mayo Clinic and Mayo Clinic Laboratories not characterized for specific resistance mechanisms, and 128 isolates with CFDC MICs of ≥8 μg/ml obtained from International Health Management Associates, Inc. (IHMA, Schaumburg, IL). Broth microdilution using standard cation-adjusted Mueller-Hinton broth (BMD) and iron-depleted cation-adjusted Mueller-Hinton broth (ID-BMD), and agar dilution (AD) using standard Mueller-Hinton agar were performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. MICs were interpreted according to the investigational CLSI, FDA, and EUCAST breakpoints, and results were compared. MICs inhibiting 50 and 90% of organisms (MIC50 and MIC90, respectively), essential agreement (EA), categorical agreement (CA), and error of different types were determined. Results showed considerable discordance between AD and ID-BMD. CFDC showed low EA and CA rates and high error rates for AD in comparison to ID-BMD. Overall, this study does not support use of standard AD for determining CFDC MICs.

Current Advances in Burkholderia Vaccines Development.

The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.