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BioRxiv : the Preprint Server For... Jun 2024Emerging antibiotic resistance requires continual improvement in the arsenal of antimicrobial drugs, especially the critical macrolide antibiotics. Formation of the...
Emerging antibiotic resistance requires continual improvement in the arsenal of antimicrobial drugs, especially the critical macrolide antibiotics. Formation of the macrolactone scaffold of these polyketide natural products is catalyzed by a modular polyketide synthase (PKS) thioesterase (TE). The TE accepts a linear polyketide substrate from the termina PKS acyl carrier protein to generate an acyl-enzyme adduct that is resolved by attack of a substrate hydroxyl group to form the macrolactone. Our limited mechanistic understanding of TE selectivity for a substrate nucleophile and/or water has hampered development of TEs as biocatalysts that accommodate a variety of natural and non-natural substrates. To understand how TEs direct the substrate nucleophile for macrolactone formation, acyl-enzyme intermediates were trapped as stable amides by substituting the natural serine OH with an amino group. Incorporation of the unnatural amino acid, 1,3-diaminopropionic acid (DAP), was tested with five PKS TEs. DAP-modified TEs (TE ) from the pikromycin and erythromycin pathways were purified and tested with six full-length polyketide intermediates from three pathways. The erythromycin TE had permissive substrate selectivity, whereas the pikromycin TE was selective for its native hexaketide and heptaketide substrates. In a crystal structure of a native substrate trapped in pikromycin TE , the linear heptaketide was curled in the active site with the nucleophilic hydroxyl group positioned 4 Å from the amide-enzyme linkage. The curled heptaketide displayed remarkable shape complementarity with the TE acyl cavity. The strikingly different shapes of acyl cavities in TEs of known structure, including those reported here for juvenimicin, tylosin and fluvirucin biosynthesis, provide new insights to facilitate TE engineering and optimization.
PubMed: 38948807
DOI: 10.1101/2024.06.20.599880 -
BMC Infectious Diseases Jun 2024An improper host immune response to Mycoplasma pneumoniae generates excessive inflammation, which leads to the impairment of pulmonary ventilation function (PVF).... (Meta-Analysis)
Meta-Analysis
BACKGROUND
An improper host immune response to Mycoplasma pneumoniae generates excessive inflammation, which leads to the impairment of pulmonary ventilation function (PVF). Azithromycin plus inhaled terbutaline has been used in the treatment of Mycoplasma pneumoniae pneumonia (MPP) in children with impaired pulmonary function, but previous randomized controlled trials (RCTs) showed inconsistent efficacy and safety. This study is aimed to firstly provide a systematic review of the combined therapy.
METHODS
This study was registered at the International Prospective Register of Systematic Reviews (PROSPERO CRD42023452139). A PRISMA-compliant systematic review and meta-analysis was performed. Six English and four Chinese databases were comprehensively searched up to June, 2023. RCTs of azithromycin sequential therapy plus inhaled terbutaline were selected. The revised Cochrane risk of bias tool for randomized trials (RoB2) was used to evaluate the methodological quality of all studies, and meta-analysis was performed using Stata 15.0 with planned subgroup and sensitivity analyses. Publication bias was evaluated by a funnel plot and the Harbord' test. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation recommendations.
RESULTS
A total of 1,938 pediatric patients from 20 RCTs were eventually included. The results of meta-analysis showed that combined therapy was able to significantly increase total effectiveness rate (RR = 1.20, 95%CI 1.15 to 1.25), forced expiratory volume in one second (SMD = 1.14, 95%CIs, 0.98 to 1.29), the ratio of forced expiratory volume in one second/forced vital capacity (SMD = 2.16, 95%CIs, 1.46 to 2.86), peak expiratory flow (SMD = 1.17, 95%CIs, 0.91 to 1.43). The combined therapy was associated with a 23% increased risk of adverse reactions compared to azithromycin therapy alone, but no significant differences were found. Harbord regression showed no publication bias (P = 0.148). The overall quality of the evidence ranged from moderate to very low.
CONCLUSIONS
This first systematic review and meta-analysis suggested that azithromycin sequential therapy plus inhaled terbutaline was safe and beneficial for children with MPP. In addition, the combined therapy represented significant improvement of PVF. Due to lack of high-quality evidence, our results should be confirmed by adequately powered RCTs in the future.
Topics: Humans; Azithromycin; Terbutaline; Pneumonia, Mycoplasma; Child; Anti-Bacterial Agents; Mycoplasma pneumoniae; Drug Therapy, Combination; Administration, Inhalation; Treatment Outcome; Randomized Controlled Trials as Topic; Child, Preschool
PubMed: 38944667
DOI: 10.1186/s12879-024-09564-x -
Communications Biology Jun 2024Macrolide antibiotics, pivotal in clinical therapeutics, are confronting resistance challenges mediated by enzymes like macrolide esterases, which are classified into...
Macrolide antibiotics, pivotal in clinical therapeutics, are confronting resistance challenges mediated by enzymes like macrolide esterases, which are classified into Ere-type and the less studied Est-type. In this study, we provide the biochemical confirmation of EstX, an Est-type macrolide esterase that initially identified as unknown protein in the 1980s. EstX is capable of hydrolyzing four 16-membered ring macrolides, encompassing both veterinary (tylosin, tidipirosin, and tilmicosin) and human-use (leucomycin A5) antibiotics. It uses typical catalytic triad (Asp233-His261-Ser102) from alpha/beta hydrolase superfamily for ester bond hydrolysis. Further genomic context analysis suggests that the dissemination of estX is likely facilitated by mobile genetic elements such as integrons and transposons. The global distribution study indicates that bacteria harboring the estX gene, predominantly pathogenic species like Escherichia coli, Salmonella enterica, and Klebsiella pneumoniae, are prevalent in 74 countries across 6 continents. Additionally, the emergence timeline of the estX gene suggests its proliferation may be linked to the overuse of macrolide antibiotics. The widespread prevalence and dissemination of Est-type macrolide esterase highlight an urgent need for enhanced monitoring and in-depth research, underlining its significance as an escalating public health issue.
Topics: Esterases; Anti-Bacterial Agents; Macrolides; Humans; Bacterial Proteins; Phylogeny; Hydrolases
PubMed: 38944651
DOI: 10.1038/s42003-024-06473-2 -
Acta Tropica Jun 2024Gram-positive catalase-negative cocci (GPCNCs) are significant components of the genital microbiota in sheep and goats. However, characterizing them can be difficult due...
Gram-positive catalase-negative cocci (GPCNCs) are significant components of the genital microbiota in sheep and goats. However, characterizing them can be difficult due to overlapping culture features and the limited information on their susceptibility to antibiotics. In this study, 97 foreskin and 13 vaginal swabs were investigated using a culturomic approach. Of 110 animals, 76 (69.09%) hosted GPCNCs, including strains from Streptococcaceae (37, 33.64%), Aerococcaceae (30, 27.27%), Enterococcaceae (6, 5.45%) and other minor species. With increasing antimicrobial resistance rates in livestock, surveillance programs are globally required, so we conducted a pilot study on GPCNCs isolated from the genital mucosa surfaces of sheep and goats using the minimal inhibitory concentration assay (MIC). Due to gaps in interpretative standard breakpoints, normalized resistance interpretation was used for setting epidemiological susceptibility cut-off values (CO). Of 57 suitable strains, the majority (80.71%) showed high CO with decrease susceptibility to at least one antimicrobial class, with 22.81% displaying multiresistant profiles. Of interest, combined resistances to beta-lactams, macrolides, lincosamides, and tetracyclines were detected in strains of Streptococcus plurianimalium. Further combinations, including resistance to beta-lactams, pleuromutilins, aminoglycosides, and lincosamides, were also recorded in both Streptococcus uberis and Enterococcus spp. strains. Being beta-lactams, macrolides, and tetracyclines the most used antibiotics in livestock worldwide, our results highlight the need for their prudent use. Collectively, our findings highlight that small ruminant genital microbiota can serve as reservoirs for opportunistic severe pathogens, often zoonotic, carrying multidrug resistances, thus standing for high risks for both animals and humans.
PubMed: 38944406
DOI: 10.1016/j.actatropica.2024.107305 -
Antimicrobial Agents and Chemotherapy Jun 2024Intrinsic resistance to macrolides in Gram-negative bacteria is primarily attributed to the low permeability of the outer membrane, though the underlying genetic and...
Intrinsic resistance to macrolides in Gram-negative bacteria is primarily attributed to the low permeability of the outer membrane, though the underlying genetic and molecular mechanisms remain to be fully elucidated. Here, we used transposon directed insertion-site sequencing (TraDIS) to identify chromosomal non-essential genes involved in intrinsic resistance to a macrolide antibiotic, tilmicosin. We constructed two highly saturated transposon mutant libraries of >290,000 and >390,000 unique Tn5 insertions in a clinical enterotoxigenic strain (ETEC5621) and in a laboratory strain (K-12 MG1655), respectively. TraDIS analysis identified genes required for growth of ETEC5621 and MG1655 under 1/8 MIC ( = 15 and 16, respectively) and 1/4 MIC ( = 38 and 32, respectively) of tilmicosin. For both strains, 23 genes related to lipopolysaccharide biosynthesis, outer membrane assembly, the Tol-Pal system, efflux pump, and peptidoglycan metabolism were enriched in the presence of the antibiotic. Individual deletion of genes ( = 10) in the wild-type strains led to a 64- to 2-fold reduction in MICs of tilmicosin, erythromycin, and azithromycin, validating the results of the TraDIS analysis. Notably, deletion of or , which impairs the outer membrane, led to the most significant decreases in MICs of all three macrolides in ETEC5621. Our findings contribute to a genome-wide understanding of intrinsic macrolide resistance in , shedding new light on the potential role of the peptidoglycan layer. They also provide an proof of concept that can be sensitized to macrolides by targeting proteins maintaining the outer membrane such as SurA and WaaG.
PubMed: 38940570
DOI: 10.1128/aac.00452-24 -
Frontiers in Bioscience (Landmark... Jun 2024The inhibitors of mammalian target of rapapmycin (mTOR), everolimus, temsirolimus and rapamycin, have a wide range of clinical utility; however, as is inevitably the... (Review)
Review
The inhibitors of mammalian target of rapapmycin (mTOR), everolimus, temsirolimus and rapamycin, have a wide range of clinical utility; however, as is inevitably the case with other chemotherapeutic agents, resistance development constrains their effectiveness. One putative mechanism of resistance is the promotion of autophagy, which is a direct consequence of the inhibition of the mTOR signaling pathway. Autophagy is primarily considered to be a cytoprotective survival mechanism, whereby cytoplasmic components are recycled to generate energy and metabolic intermediates. The autophagy induced by everolimus and temsirolimus appears to play a largely protective function, whereas a cytotoxic function appears to predominate in the case of rapamycin. In this review we provide an overview of the autophagy induced in response to mTOR inhibitors in different tumor models in an effort to determine whether autophagy targeting could be of clinical utility as adjuvant therapy in association with mTOR inhibition.
Topics: Humans; Autophagy; TOR Serine-Threonine Kinases; MTOR Inhibitors; Animals; Neoplasms; Signal Transduction; Antineoplastic Agents; Cytoprotection; Sirolimus
PubMed: 38940039
DOI: 10.31083/j.fbl2906231 -
Open Forum Infectious Diseases Jun 2024Antimicrobial resistance (AMR) is a global threat to infectious disease control, particularly among recently hospitalized children. We sought to determine the prevalence...
BACKGROUND
Antimicrobial resistance (AMR) is a global threat to infectious disease control, particularly among recently hospitalized children. We sought to determine the prevalence and mitigating factors of resistance in enteric among children discharged from health facilities in western Kenya.
METHODS
Between June 2016 and November 2019, children aged 1 to 59 months were enrolled at the point of discharge from the hospital. was isolated by microbiological culture from rectal swabs at baseline. β-Lactamases and macrolide resistance-conferring genes were detected by polymerase chain reaction. A modified Poisson regression model was used to assess the predictors (A) and CTX-M-type extended-spectrum β-lactamase (ESBL).
RESULTS
Of the 238 children whose isolates were tested, 91 (38.2%) and 109 (45.8%) had detectable CTX-M-type ESBL and (A) genes, respectively. Antibiotic treatment during hospitalization (adjusted prevalence ratio [aPR], 2.47; 95% CI, 1.12-5.43; = .025), length of hospitalization (aPR, 1.42; 95% CI, 1.00-2.01; = .052), and the practice of open defecation (aPR, 2.47; 95% CI, 1.40-4.36; = .002) were independent predictors for CTX-M-type ESBL and (A) genes. Pneumococcal vaccination was associated with a 43% lower likelihood of CTX-M-type ESBL (aPR, 0.57; 95% CI, .38-.85; = .005), while measles vaccination was associated with a 32% lower likelihood of (A) genes (aPR, 0.68; 95% CI, .49-.93; = .017) in isolates.
CONCLUSIONS
Among children discharged from the hospital, history of vaccination, shorter hospital stay, lack of in-hospital antibiotic exposure, and improved sanitation were associated with a lower likelihood of AMR genes. To mitigate the continued spread of AMR, AMR control programs should consider strategies beyond antimicrobial stewardship, including improvements in sanitation, increased vaccine coverage, and the development of novel vaccines.
PubMed: 38938894
DOI: 10.1093/ofid/ofae307 -
Open Veterinary Journal May 2024Young farm animals are susceptible to opportunistic infections which may cause economic losses due to mortality and poor weight gain. The development of antimicrobial...
BACKGROUND
Young farm animals are susceptible to opportunistic infections which may cause economic losses due to mortality and poor weight gain. The development of antimicrobial resistance and the desire to improve therapy efficacy and safety are the reasons to seek for new antibacterial drugs ensuring rapid recovery with minimum adverse events.
AIM
To estimate the efficacy of DOKSI AVZ 500 in respiratory pathologies in young pigs.
METHODS
The study was conducted in 65-70-day-old Yorkshire piglets with signs of bacterial respiratory pathologies. The animals were treated with the test drug for 3 or 5 days. The reference group received TETRAMAX 500 which is similar to the test drug in terms of chemical structure, mechanism of action, and activity spectrum. The animal's status was assessed using clinical examination, clinical blood count, and bacteriological tests.
RESULTS
Both test and reference drugs were well tolerated and ensured the animal recovery within about 4 days. The recovery was accompanied by normalization of hematological parameters and flora composition. The bacterium associated with the disease development, , was virtually completely eliminated in all groups. No adverse events were noted. After the treatment, all the animals readily gained weight and live market quality.
CONCLUSION
DOKSI AVZ 500 was a highly efficient therapy for respiratory pathologies caused by the resident opportunistic flora in piglets. It has also shown noninferiority TETRAMAX 500 in terms of all the health-related parameters and thus can be recommended for introduction in veterinary practice in pig farms.
Topics: Animals; Swine; Swine Diseases; Anti-Bacterial Agents; Respiratory Tract Infections; Female; Male; Tylosin
PubMed: 38938427
DOI: 10.5455/OVJ.2024.v14.i5.2 -
BMC Infectious Diseases Jun 2024Refractory Helicobacter pylori (H. pylori) infection inevitably increase the difficulty of drug selection. Here, we described our experience with the use of a novel... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Refractory Helicobacter pylori (H. pylori) infection inevitably increase the difficulty of drug selection. Here, we described our experience with the use of a novel tetravalent IgY against H. pylori for the treatment of patients with refractory H. pylori infection.
METHODS
Patients were randomly assigned to receive the standard quadruple therapy (amoxicillin, clarithromycin, omeprazole and bismuth potassium citrate ) for 2 weeks or 250 mg of avian polyclonal IgY orally twice a day for 4 weeks. The binding efficacy of IgY to H. pylori antigens was detected by western blotting. C-urea breath test was performed to evaluate the eradication therap's efficacy. The side effects of IgY were evaluated via various routine tests. The questionnaire was used to gather clinical symptoms and adverse reactions.
RESULTS
Western blot analysis showed that tetravalent IgY simultaneously bind to VacA, HpaA, CagA and UreB of H. pylori. Tetravalent IgY had an eradication rate of 50.74% in patients with refractory H. pylori and an inhibition rate of 50.04% against DOB (delta over baseline) of C-urea. The symptom relief rate was 61.76% in thirty-four patients with clinical symptoms, and no adverse reactions were observed during tetravalent IgY treatment period.
CONCLUSIONS
Polyclonal avian tetravalent IgY reduced H. pylori infection, and showed good efficacy and safety in the treatment of refractory H. pylori infection patients, which represented an effective therapeutic option of choice for patients with refractory H. pylori infection.
Topics: Humans; Helicobacter Infections; Male; Female; Helicobacter pylori; Middle Aged; Immunoglobulins; Adult; Anti-Bacterial Agents; Treatment Outcome; Aged; Drug Therapy, Combination; Clarithromycin; Amoxicillin; Young Adult; Antibodies, Bacterial
PubMed: 38937679
DOI: 10.1186/s12879-024-09498-4 -
Scientific Reports Jun 2024Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus...
Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus aureus and Staphylococci other than S. aureus (SOSA) among young volunteers in Egypt to determine their risk potential. Nasal swabs collected over 1 week in June 2019 from 196 volunteers were cultured for staphylococcus isolation. The participants were interviewed to assess sex, age, general health, hospitalization and personal hygiene habits. Identification was carried out using biochemical tests and VITEK 2 automated system. Disc diffusion and minimum inhibitory concentration tests were performed to determine antibiotic susceptibility. Screening for macrolide resistance genes (ermA, ermB, ermC, ermT and msrA) was performed using polymerase chain reaction. Thirty four S. aureus and 69 SOSA were obtained. Multi-drug resistance (MDR) was detected among most staphylococcal species, ranging from 30.77% among S. hominis to 50% among S. epidermidis. Phenotypic resistance to all tested antibiotics, except for linezolid, was observed. Susceptibility to rifampicin, vancomycin and teicoplanin was highest. ermB showed the highest prevalence among all species (79.41% and 94.2% among S. aureus and SOSA, respectively), and constitutive macrolide-lincosamide-streptogramin B (MLS) resistance was equally observed in S. aureus and SOSA (11.11% and 16.22%, respectively), whereas inducible MLS resistance was more often found in S. aureus (77.78% and 43.24%, respectively). The species or resistance level of the carried isolates were not significantly associated with previous hospitalization or underlying diseases. Although over all colonization and carriage of resistance genes are within normal ranges, the increased carriage of MDR S. aureus is alarming. Also, the fact that many macrolide resitance genes were detected should be a warning sign, particularly in case of MLS inducible phenotype. More in depth analysis using whole genome sequencing would give a better insight into the MDR staphylococci in the community in Egypt.
Topics: Humans; Egypt; Female; Male; Staphylococcus; Microbial Sensitivity Tests; Staphylococcal Infections; Anti-Bacterial Agents; Adult; Phenotype; Young Adult; Genotype; Staphylococcus aureus; Drug Resistance, Multiple, Bacterial; Adolescent
PubMed: 38937465
DOI: 10.1038/s41598-024-60924-8