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Many countries have reported increasing rates of penicillin-susceptible methicillin-sensitive Staphylococcus aureus (MSSA-PEN S ). To date, there is relatively little known about the current situation and molecular characteristics of MSSA-PEN S in China. In this study, we carried out a laboratory-based multi-region retrospective study to investigate the genomic epidemiology and characterisation of MSSA-PEN S isolated from invasive bloodstream infections (BSIs) across 17 provinces. The prevalence of MSSA-PEN S isolates increased significantly over the 6-year period, with the proportion increasing from 3.51% in 2014-8.80% in 2019, an average relative increase of 22.14% per year (95% confidence interval 9.67%-34.61%, P for trend <0.001), suggesting that China is experiencing a resurgence of MSSA-PEN S . Phylogenetic analysis showed a higher strain diversity occurred; the most frequent clonal complexes (CCs) identified were CC188 (17.14%), CC398 (15.71%) and CC5 (15.71%). Over half of MSSA-PEN S strains were pan-susceptible, with erythromycin the most frequent resistance observed. Moreover, 25 isolates were identified as immune evasion cluster negative, including CC15, CC188 and CC1, and 6 strains encoded the Panton-Valentine leucocidin gene. Importantly, virulence assays showed that MSSA-PEN S exhibited a level of virulence comparable to that of penicillin-resistant MSSA (MSSA-PEN R ), indicating that more-sensitive strains should not be mistaken for lacking aggressiveness in vivo. Furthermore, 11 of these isolates were confirmed as blaZ positive but phenotype sensitive, with different amino acid changes in blaZ. Our data support the recommendation to clinicians regarding the usage of penicillin in invasive BSIs caused by MSSA-PEN S , which might create a novel opportunity for better antimicrobial stewardship in the future.

Maternal anaphylaxis is rare albeit life-threatening critical incident dreaded by many due to negative effects on not only the mother but the foetus as well. Antibiotics and anaesthetic agents still contribute to majority of the episodes. Consequences of anaphylaxis such as placental insufficiency and subsequent foetal neurocognitive deficits are devastating outcomes. Acute respiratory distress syndrome following anaphylaxis is even rarer among the normal population. The management of maternal anaphylaxis does not differ from routine recommendations even though close monitoring and preparedness for early delivery should be embedded in the protocols. This is a rare case report of a primi mother who developed anaphylactic shock following intravenous penicillin in the background of negative allergic history, resultant foetal distress requiring emergency lower segment caesarian section and delayed onset acute respiratory distress syndrome which was later attributed to anaphylaxis. Pertinent identification and management which included a multidisciplinary team culminated in favourable outcomes.

Background: Chlamydomonas reinhardtii , a green micro-alga can be grown at the lab heterotrophically or photo-heterotrophically in Tris-Phosphate-Acetate (TAP) medium which contains acetate as the sole carbon source. When grown in TAP medium, Chlamydomonas can utilize the exogenous acetate in the medium for gluconeogenesis using the glyoxylate cycle, which is also present in many bacteria and higher plants. A novel bacterial strain, LMJ, was isolated from a contaminated TAP medium plate of Chlamydomonas . We present our work on the isolation and physiological and biochemical characterizations of LMJ. Methods: Several microbiological tests were conducted to characterize LMJ, including its sensitivity to four antibiotics. We amplified and sequenced partially the 16S rRNA gene of LMJ. We tested if LMJ can utilize cyclic alkanes, aromatic hydrocarbons, poly-hydroxyalkanoates, and fresh and combusted car motor oil as the sole carbon source on Tris-Phosphate (TP) agar medium plates for growth. Results: LMJ is a gram-negative rod, oxidase-positive, mesophilic, non-enteric, pigmented, salt-sensitive bacterium. LMJ can ferment glucose, is starch hydrolysis-negative, and is very sensitive to penicillin and chloramphenicol. Preliminary spectrophotometric analyses indicate LMJ produces pyomelanin. NCBI-BLAST analyses of the partial 16S rRNA gene sequence of LMJ showed that it matched to that of an uncultured bacterium clone LIB091_C05_1243. The nearest genus relative of LMJ is an Acidovorax sp. strain. LMJ was able to use alkane hydrocarbons, fresh and combusted car motor oil, poly-hydroxybutyrate, phenanthrene, naphthalene, benzoic acid and phenyl acetate as the sole carbon source for growth on TP-agar medium plates. Conclusions: LMJ has 99.14% sequence identity with the Acidovorax sp. strain A16OP12 whose genome has not been sequenced yet. LMJ’s ability to use chemicals that are common environmental pollutants makes it a promising candidate for further investigation for its use in bioremediation and, provides us with an incentive to sequence its genome.

Streptococcus pneumoniae ( S. pneumoniae ) has developed resistance to β-lactam antibiotics, largely due to mutations in penicillin-binding protein 2x (PBP2x), particularly within conserved motifs such as STMK and KSG. PBP2x mutations are frequently reported in multidrug-resistant pneumococcal strains associated with pneumonia, meningitis, and septicaemia. especially in serotypes 19A, 19F, and 23F, showing reduced susceptibility to β-lactam antibiotics. These mutations in the PBP2x disrupt antibiotic binding and enzymatic functions, highlighting the need for alternative therapeutic strategies. This study focused on five clinically relevant PBP2x mutations (T338A/G/P and K547G/T) within its active site. A library of phytocompounds was screened using a machine learning model trained to identify antibacterial compounds. Top candidates were filtered based on ADMET properties, and their electronic characteristics were assessed using HOMO–LUMO analysis and electrostatic potential mapping, through density functional theory (DFT). Glucozaluzanin C, a phytochemical derived from Elephantopus scaber , emerged as a potential candidate. Molecular docking and dynamics simulations revealed strong binding affinity and structural integrity with all PBP2x mutants, over a 100-ns timescale. RMSD, RMSF, and hydrogen bonding analysis confirmed stable interactions, suggesting Glucozaluzanin C may effectively interact with PBP2x mutants. Overall, the study highlights an effective strategy for identifying plant-derived inhibitors against β-lactam-resistant S. pneumoniae.

Infections caused by multidrug-resistant Streptococcus pneumoniae remain the leading cause of pneumonia-related deaths in children < 5 years globally, and mutations in penicillin-binding protein (PBP) 2 × have been identified as the major cause of resistance in the organism to beta-lactams. Thus, the development of new modulators with enhanced binding of PBP2x is highly encouraged. In this study, phenolics, due to their reported antibacterial activities, were screened against the active site of PBP2x using structure-based pharmacophore and molecular docking techniques, and the ability of the top-hit phenolics to inhibit the active and allosteric sites of PBP2x was refined through 120 ns molecular dynamic simulation. Except for gallocatechin gallate and lysidicichin, respectively, at the active and allosteric sites of PBP2x, the top-hit phenolics had higher negative binding free energy (ΔG bind ) than amoxicillin [active site (− 19.23 kcal/mol), allosteric site (− 33.75 kcal/mol)]. Although silicristin had the best broad-spectrum effects at the active (− 38.41 kcal/mol) and allosteric (− 50.54 kcal/mol) sites of PBP2x, the high thermodynamic entropy (4.90 Å) of the resulting complex might suggest the need for its possible structural refinement for enhanced potency. Interestingly, silicristin had a predicted synthetic feasibility score of < 5 and quantum calculations using the DFT B3LYP/6-31G+ (dp) revealed that silicristin is less stable and more reactive than amoxicillin. These findings point to the possible benefits of the top-hit phenolics, and most especially silicristin, in the direct and synergistic treatment of infections caused by S. pneumoniae . Accordingly, silicristin is currently the subject of further confirmatory in vitro research.

Broad-spectrum antibiotics for suspected early-onset neonatal sepsis (sEONS) may have pronounced effects on gut microbiome development and selection of antimicrobial resistance when administered in the first week of life, during the assembly phase of the neonatal microbiome. Here, 147 infants born at ≥36 weeks of gestational age, requiring broad-spectrum antibiotics for treatment of sEONS in their first week of life were randomized 1:1:1 to receive three commonly prescribed intravenous antibiotic combinations, namely penicillin + gentamicin, co-amoxiclav + gentamicin or amoxicillin + cefotaxime (ZEBRA study, Trial Register NL4882). Average antibiotic treatment duration was 48 hours. A subset of 80 non-antibiotic treated infants from a healthy birth cohort served as controls (MUIS study, Trial Register NL3821). Rectal swabs and/or faeces were collected before and immediately after treatment, and at 1, 4 and 12 months of life. Microbiota were characterized by 16S rRNA-based sequencing and a panel of 31 antimicrobial resistance genes was tested using targeted qPCR. Confirmatory shotgun metagenomic sequencing was executed on a subset of samples. The overall gut microbial community composition and antimicrobial resistance gene profile majorly shift directly following treatment (R 2  = 9.5%, adjusted p -value = 0.001 and R 2  = 7.5%, adjusted p -value = 0.001, respectively) and normalize over 12 months (R 2  = 1.1%, adjusted p -value = 0.03 and R 2  = 0.6%, adjusted p -value = 0.23, respectively). We find a decreased abundance of Bifidobacterium spp. and increased abundance of Klebsiella and Enterococcus spp. in the antibiotic treated infants compared to controls. Amoxicillin + cefotaxime shows the largest effects on both microbial community composition and antimicrobial resistance gene profile, whereas penicillin + gentamicin exhibits the least effects. These data suggest that the choice of empirical antibiotics is relevant for adverse ecological side-effects. Here, in a randomized trial of 147 infants receiving distinct antibiotic regimens for early-onset neonatal sepsis, Reyman et al. characterize the gut microbiome and resistance profiles, finding differential effects of antibiotic combinations on microbial community composition and antimicrobial resistance genes.

A recent study in a Medicaid population indicated an increased risk of cardiovascular death with azithromycin. The current study in a population in Denmark indicates no increase in risk. In a related Perspective, the FDA reviews its reasons for adding a warning of increased risk to the drug label. Azithromycin is a macrolide antibiotic agent primarily used for the treatment of lower and upper respiratory infections and some sexually transmitted infections. This commonly used agent is considered to be generally free of serious adverse effects, including cardiac toxicity. 1 – 5 A recent observational study, however, showed that use of azithromycin was associated with a risk of death from cardiovascular causes that was 2 to 3 times as high as the risk associated with no use of antibiotics and the risk associated with amoxicillin treatment. 6 Given that certain other macrolides are known to prolong the QT interval and therefore are thought . . .

In the face of increasing antimicrobial tolerance and resistance there is a global obligation to optimise oral antimicrobial dosing strategies including narrow spectrum penicillins, such as penicillin-V. We conducted a randomised, crossover study in healthy volunteers to characterise the influence of probenecid on penicillin-V pharmacokinetics and estimate the pharmacodynamics against Streptococcus pneumoniae . Twenty participants took six doses of penicillin-V (250 mg, 500 mg or 750 mg four times daily) with and without probenecid. Total and free concentrations of penicillin-V and probenecid were measured at two timepoints. A pharmacokinetic model was developed, and the probability of target attainment (PTA) calculated. The mean difference (95% CI) between penicillin-V alone and in combination with probenecid for serum total and free penicillin-V concentrations was significantly different at both timepoints (total: 45 min 4.32 (3.20–5.32) mg/L p  <  0.001 , 180 min 2.2 (1.58–3.25) mg/L p  <  0.001 ; free: 45 min 1.15 (0.88–1.42) mg/L p  <  0.001 , 180 min 0.5 (0.35–0.76) mg/L p  <  0.001 ). There was no difference between the timepoints in probenecid concentrations. PTA analysis shows probenecid allows a fourfold increase in MIC cover. Addition of probenecid was safe and well tolerated. The data support further research into improved dosing structures for complex outpatient therapy and might also be used to address penicillin supply shortages.

The synthon 3-(anthracen-9-yl)-2-cyanoacryloyl chloride 4 was produced and exploited in the creation of a wide variety of highly reactive heterocyclic compounds, by its interaction with diverse nitrogen nucleophiles. Using spectral and elemental analysis, the structures of each synthesized heterocycles were fully investigated. Ten of the thirteen novel heterocycles showed encouraging efficacy against antibiotic-resistant bacteria (MRSA). Among these, compounds 6 , 7 , 10 , 13b , and 14 demonstrated the highest antibacterial activity, showing inhibition zones near 4 cm. However, molecular docking studies revealed varied binding affinities for Penicillin-Binding Protein 2a (PBP2a), a crucial target in MRSA resistance. Some compounds, such as 7 , 10 , and 14 , displayed higher binding affinities and interaction stability within the PBP2a active site compared to the co-crystallized quinazolinone ligand. In contrast, compounds 6 and 13b exhibited lower docking scores but still showed substantial antimicrobial activity, with 6 showing the lowest MIC (9.7 μg/100 μL) and MBC (78.125 μg/100 μL) values. The docking analysis revealed key interactions, including hydrogen bonding and π-stacking, particularly with residues like Lys 273 , Lys 316 , and Arg 298 , which were identified as interacting with the co-crystallized ligand within the crystal structure of PBP2a . These residues are essential for the enzymatic activity of PBP2a. These findings suggest that the synthesized compounds could serve as promising anti-MRSA agents, highlighting the importance of integrating molecular docking with biological assays to identify effective therapeutic candidates.

The recent demonstration that naturally occurring amino acid substitutions in Streptococcus pyogenes PBP2X are sufficient to cause severalfold reduced susceptibility to multiple β-lactam antibiotics in vitro raises the concern that these therapeutic agents may become compromised. Substitutions in PBP2X are common first-step mutations that, with the incremental accumulation of additional adaptive mutations within the PBPs, can result in high-level resistance. Identification of genetic polymorphisms causing increased antibiotic resistance in bacterial pathogens traditionally has proceeded from observed phenotype to defined mutant genotype. The availability of large collections of microbial genome sequences that lack antibiotic susceptibility metadata provides an important resource and opportunity to obtain new information about increased antimicrobial resistance by a reverse genotype-to-phenotype bioinformatic and experimental workflow. We analyzed 26,465 genome sequences of Streptococcus pyogenes , a human pathogen causing 700 million infections annually. The population genomic data identified amino acid changes in penicillin-binding proteins 1A, 1B, 2A, and 2X with signatures of evolution under positive selection as potential candidates for causing decreased susceptibility to β-lactam antibiotics. Construction and analysis of isogenic mutant strains containing individual amino acid replacements in penicillin-binding protein 2X (PBP2X) confirmed that the identified residues produced decreased susceptibility to penicillin. We also discovered the first chimeric PBP2X in S. pyogenes and show that strains containing it have significantly decreased β-lactam susceptibility. The novel integrative reverse genotype-to-phenotype strategy presented is broadly applicable to other pathogens and likely will lead to new knowledge about antimicrobial agent resistance, a massive public health problem worldwide. IMPORTANCE The recent demonstration that naturally occurring amino acid substitutions in Streptococcus pyogenes PBP2X are sufficient to cause severalfold reduced susceptibility to multiple β-lactam antibiotics in vitro raises the concern that these therapeutic agents may become compromised. Substitutions in PBP2X are common first-step mutations that, with the incremental accumulation of additional adaptive mutations within the PBPs, can result in high-level resistance. Because β-lactam susceptibility testing is not routinely performed, the nature and extent of such substitutions within the PBPs of S. pyogenes are poorly characterized. To address this knowledge deficit, polymorphisms in the PBPs were identified among the most comprehensive cohort of S. pyogenes genome sequences investigated to date. The mutational processes and selective forces acting on the PBPs were assessed to identify specific substitutions likely to influence β-lactam susceptibility and to evaluate factors posited to be impediments to resistance emergence.