Beta-lactam Antibiotics Research Articles

Potential involvement of beta-lactamase homologous proteins in resistance to beta-lactam antibiotics in gram-negative bacteria of the ESKAPEE group

BackgroundEnzymatic degradation mediated by beta-lactamases constitutes one of the primary mechanisms of resistance to beta-lactam antibiotics in gram-negative bacteria. This enzyme family comprises four molecular classes, categorized into serine beta-lactamases (Classes A, C, and D) and zinc-dependent metallo-beta-lactamases (Class B). Gram-negative bacteria producing beta-lactamase are of significant concern, particularly due to their prevalence in nosocomial infections. A comprehensive understanding of the evolution and dissemination of this enzyme family is essential for effective control of these pathogens.In this study, we conducted the prospecting, phylogenetic analysis, and in silico analysis of beta-lactamases and homologous proteins identified in 1827 bacterial genomes with phenotypic data on beta-lactam resistance. These genomes were distributed among Klebsiella pneumoniae (45%), Acinetobacter baumannii (31%), Pseudomonas aeruginosa (14%), Escherichia coli (6%), and Enterobacter spp. (4%). Using an HMM profile and searching for conserved domains, we mined 2514, 8733, 5424, and 2957 proteins for molecular classes A, B, C, and D, respectively. This set of proteins encompasses canonical subfamilies of beta-lactamases as well as hypothetical proteins and other functional groups. Canonical beta-lactamases were found to be phylogenetically distant from hypothetical proteins, which, in turn, are closer to other representatives of the penicillin-binding-protein (PBP-like) and metallo-beta-lactamase (MBL) families. The catalytic amino acid residues characteristic of beta-lactamases were identified from the sequence alignment and revealed that motifs are less conserved in homologous groups than in beta-lactamases. After comparing the frequency of protein groups in genomes of resistant strains with those of sensitive ones applying Fisher’s exact test and relative risk, it was observed that some groups of homologous proteins to classes B and C are more common in the genomes of resistant strains, particularly to carbapenems.We identified the beta-lactamase-like domain widely distributed in gram-negative species of the ESKAPEE group, which highlights its importance in the context of beta-lactam resistance. Some hypothetical homologous proteins have been shown to potentially possess promiscuous activity against beta-lactam antibiotics, however, they do not appear to expressly determine the resistance phenotype. The selective pressure due to the widespread use of antibiotics may favor the optimization of these functions for specialized resistance enzymes.

Structure-Based Virtual Screening, ADMET Properties Prediction and Molecular Dynamics Studies Reveal Potential Inhibitors of Mycoplasma pneumoniae HPrK/P.

Mycoplasma pneumoniae pneumonia (MPP) is a frequent cause of community-acquired pneumonia (CAP) in children. The incidence of childhood pneumonia caused by M. pneumoniae infection has been rapidly increasing worldwide. M. pneumoniae is naturally resistant to beta-lactam antibiotics due to its lack of a cell wall. Macrolides and related antibiotics are considered the optimal drugs for treating M. pneumoniae infection. However, clinical resistance to macrolides has become a global concern in recent years. Therefore, it is imperative to urgently identify new targets and develop new anti-M. pneumoniae drugs to treat MMP. Previous studies have shown that deficiencies in HPrK/P kinase or phosphorylase activity can seriously affect carbon metabolism, growth, morphology, and other cellular functions of M. pneumoniae. To identify potential drug development targets against M. pneumoniae, this study analyzed the sequence homology and 3D structure alignment of M. pneumoniae HPrK/P. Through sequence and structure analysis, we found that HPrK/P lacks homologous proteins in the human, while its functional motifs are highly conserved in bacteria. This renders it a promising candidate for drug development. Structure-based virtual screening was then used to discover potential inhibitors among 2614 FDA-approved drugs and 948 bioactive small molecules for M. pneumoniae HPrK/P. Finally, we identified three candidate drugs (Folic acid, Protokylol and Gluconolactone) as potential HPrK/P inhibitors through molecular docking, molecular dynamics (MDs) simulations, and ADMET predictions. These drugs offer new strategies for the treatment of MPP.

Meropenem/Vaborbactam-A Mechanistic Review for Insight into Future Development of Combinational Therapies.

Beta-lactam antibiotics have been a major climacteric in medicine for being the first bactericidal compound available for clinical use. They have continually been prescribed since their development in the 1940s, and their application has saved an immeasurable number of lives. With such immense use, the rise in antibiotic resistance has truncated the clinical efficacy of these compounds. Nevertheless, the synergism of combinational antibiotic therapy has allowed these drugs to burgeon once again. Here, the development of meropenem with vaborbactam-a recently FDA-approved beta-lactam combinational therapy-is reviewed in terms of structure rationale, activity gamut, pharmacodynamic/pharmacokinetic properties, and toxicity to provide insight into the future development of analogous therapies.

Theoretical study of the hydrolysis mechanism of β-lactam antibiotics catalysed by a Zn(II) dinuclear biomimetic organometallic complex

The degradation and metabolism of antibiotics have attracted the scientific community's attention due to the environmental problems caused by the inappropriate use and disposal of these drugs. Therefore, it is crucial to understand the reaction mechanism involved in the degradation of these compounds. We studied the hydrolysis of nitrocefin and benzylpenicillin, two β-lactam ring antibiotics, mediated by an enzymatic mimetic Zn organometallic compound, using DFT methods. The electronic effects of functional groups adjacent to the β-lactam ring were analysed and good agreement between experimental and theoretical results was found. The reaction involves the nucleophilic attack of the bridging hydroxide group on the Zn atoms towards the β-lactam ring. A stepwise mechanism was found to agree with the experimental results. Chemical hardness profiles were affected by the solvent and reaction synchronicity. Geometric rearrangements dominated the activation barrier, and both antibiotics exhibited late transition states.

Cefiderocol – An effective antimicrobial for MDR infections but a challenge for routine antimicrobial susceptibility testing

PurposeCefiderocol is a novel cephalosporin–siderophore conjugate antibiotic that holds promise to thwart infections caused by multi-drug-resistant gram-negative bacilli. Its antibacterial activity against normally susceptible species is not affected by most β-lactamases, including metallo-β-lactamases. Due to the siderophore-mediated entry into the cell, the activity of cefiderocol is less affected by porin loss or active efflux resistance than many other β-lactam antibiotics. The aim of this study was to assess in vitro susceptibility to the cefiderocol of carbapenemase-producing gram-negative bacilli from clinical samples of hospitalized patients. Materials and methodsWe analyzed 102 clinical strains of carbapenemase-producing Enterobacterales and non-fermentives from hospital centers in Łódź, Poland. Antimicrobial susceptibility to cefiderocol was tested by the minimum inhibitory concentration test strips and disc diffusion methods. ResultsThe obtained results turned out to be ambiguous, and the area of technical uncertainty made their interpretation very difficult. ConclusionsThe cost of therapy with this antibiotic, and difficulties in interpreting the drug susceptibility are the limitations to the use of cefiderocol. Intensive work should be carried out to finally standardize an easily accessible and reliable method for the determination of susceptibility to cefiderocol.

Antibiotic resistance of heterotrophic bacteria from the sediments of adjoining high Arctic fjords, Svalbard.

Antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) are now considered major global threats. The Kongsfjorden and Krossfjorden are the interlinked fjords in the Arctic that are currently experiencing the effects of climate change and receiving input of pollutants from distant and regional sources. The present study focused on understanding the prevalence of antibiotic resistance of retrievable heterotrophic bacteria from the sediments of adjacent Arctic fjords Kongsfjorden and Krossfjorden. A total of 237 bacterial isolates were tested against 16 different antibiotics. The higher resistance observed towards Extended Spectrum β-lactam antibiotic (ESBL) includes ceftazidime (45.56%) followed by trimethoprim (27%) and sulphamethizole (24.05%). The extent of resistance was meagre against tetracycline (2.53%) and gentamycin (2.95%). The 16S rRNA sequencing analysis identified that Proteobacteria (56%) were the dominant antibiotic resistant phyla, followed by Firmicutes (35%), Actinobacteria (8%) and Bacteroidetes. The dominant resistant bacterial isolates are Bacillus cereus (10%), followed by Alcaligenes faecalis (6.47%), Cytobacillus firmus (5.75%) Salinibacterium sp. (5%) and Marinobacter antarcticus (5%). Our study reveals the prevalence of antibiotic resistance showed significant differences in both the inner and outer fjords of Kongsfjorden and Krossfjorden (p < 0.05). This may be the input of antibiotic resistance bacteria released into the fjords from the preserved permafrost due to the melting of glaciers, horizontal gene transfer, and human influence in the Arctic region act as a selection pressure for the development and dissemination of more antibiotic resistant bacteria in Arctic fjords.

A Concurrent Extended Spectrum Beta-lactamase Production and Multidrug Resistance among Proteus Species isolated from Clinical samples of patients attending selected Hospitals in North Eastern Nigeria.

Proteus species are rod-shaped, Gram-negative bacteria that cause opportunistic infections in the urinary tract and occasionally in the gastrointestinal tract. They are implicated in infections like cystitis and pyelonephritis, particularly in immunocompromised individuals, and are frequently present in cases of asymptomatic bacteriuria. Herein, we aimed to investigate the co-occurrence of extended-spectrum beta-lactamase (ESBL) enzyme production and multidrug resistance (MDR) among Proteus spp. Isolated from patients attending selected hospitals in Northeastern Nigeria. A total of 1,500 clinical samples from consenting patients across six states in the Northeastern region of Nigeria were collected. The samples were cultured on Blood agar, and growth resembling that of Proteus species were again subcultured onto MacConkey agar to obtain discrete colonies, further confirmed using biochemical tests. Antibiotics susceptibility test was carried out for all isolates using the Kirby-Bauer disc diffusion method, coupled with a screening of the production of extended-spectrum beta-lactamase using the Combined Disc Diffusion Method. Of the 1500 samples collected, 144 yielded positive growth for Proteus spp., resulting in a prevalence rate of 9.60%. Among these Proteus isolates, three species were identified, with Proteus mirabilis (90.97%) being the most abundant, followed by Proteus vulgaris (8.33%) and Proteus penneri (0.70%). The Proteus isolates displayed significant resistance to β-lactam antibiotics, with a Mean ± SD of 96.64 ± 22.73. A substantial portion of the Proteus spp. Isolated exhibited multidrug resistance (87.89%), with Proteus mirabilis (82.27%) being the most prevalent MDR species. Moreover, about 71.0% of the Proteus spp were ESBL producers, with Proteus mirabilis (64.54%) being the most predominant. Furthermore, 67.38% of all isolates exhibited MDR and ESBL production, and Proteus mirabilis (62.41%) was the most significant among the three Proteus species. These findings highlight the occurrence of multidrug resistance and ESBL production among Proteus spp. in Northeastern Nigeria, with Proteus mirabilis particularly noteworthy. This information is crucial for guiding clinical decision-making, especially in managing infections caused by multidrug-resistant and ESBL-producing Proteus strains.

Efficacy of Green Silver Nanoparticles (GAbNPs) against Multidrug Resistance in Staphylococcus aureus from Mastitis-infected Cows

Background: Antimicrobial resistance being the major emerging problem for management of mastitis in cow hence, the research work was undertaken in a geographical area around Shirwal town in Satara district of Western Maharashtra, India to investigate the occurrence of multidrug resistance in Staphylococcus aureus (MDRSA) isolated from mastitic cow milk samples. Further assessment was carried out for antimicrobial efficacy of formulation of Green Silver Nanoparticles (GAgNPs) synthesized from Azadirechta indica against MDRSA of mastitis origin. Methods: A total of 250 milk samples from cows suspected of mastitis were screened by the California Mastitis Test (CMT). The CMT-positive samples were subjected to bacteriological investigation for the presence of S. aureus as an etiological agent. The isolates identified as S. aureus were further authenticated by the molecular method targeting 16s-rRNA and nuc gene. All isolates of S. aureus were subjected to an antimicrobial susceptibility test. The randomly selected MDRSA isolates were subjected to antimicrobial susceptibility testing with GAgNPs formulation were prepared from silver nitrate by reducing with Azadirachta indica leaf extract. Result: Out of 250 cow milk samples suspected for having mastitis were screened with CMT, 170 tested positive. From these milk samples 145 isolates of S. aureus were isolated and bacteriologically identified. When processed for antibiotic sensitivity 60 were detected having multidrug resistance. Maximum resistance was shown against beta-lactam antibiotics. GAgNP synthesized and characterized with visual appearance, spectroscopy and TEM (Transmission electron microscopy) and tested for in vitro antimicrobial efficacy against MDRSA showed significant antimicrobial property.

Unmasking Hidden Threats Global Spread of MBL Resistance Exposed

This study aims to establish a routine monitoring system for MBL enzymes to provide timely data to healthcare professionals and policy makers, enabling informed decision making on antibiotic use and resistance management. Using a combination of molecular biology techniques and data analysis, we monitor MBL activity in various institutional settings. The increasing prevalence of multidrug-resistant (MDR) bacteria is a significant threat to public health globally. Metallo-beta-lactamase (MBL), an enzyme that confers resistance to a wide range of beta-lactam antibiotics, is particularly concerning due to its ability to spread rapidly in healthcare and community settings. Despite the importance of this issue, systematic monitoring and understanding of MBL remains inadequate. Our findings reveal a significant, previously unreported presence of MBLs, underscoring the urgent need for targeted antibiotic stewardship programs. The implications of this study emphasize the importance of integrating enzyme monitoring into standard healthcare practices to reduce the spread of MDR bacteria. Highlights: Regular Monitoring: Essential for tracking MBL enzyme prevalence and guiding antibiotic use. Advanced Techniques: Molecular biology methods enhance MBL detection and analysis. Policy Integration: Crucial for implementing enzyme monitoring in healthcare to combat MDR bacteria spread. Keywords: MBL Enzymes, Antibiotic Resistance, Healthcare Monitoring, Molecular Biology, Stewardship Programs

Epidemiological Study of Pathogens in Spontaneous Bacterial Peritonitis in 2017-2024-A Preliminary Report of the University Hospital in South-Eastern Poland.

Spontaneous Bacterial Peritonitis (SBP) is a serious complication and a common cause of death in patients with liver cirrhosis. Between January 2017 and March 2024, a retrospective study was conducted involving 302 patients (>18 years old) with ascites treated at a tertiary referral center in south-eastern Poland. Microbiological analysis of the ascitic fluids was performed in all patients. The presence of microorganisms was found in samples from 17 patients, and 21 pathogens were isolated, including 15 Gram-positive bacteria and 6 Gram-negative bacteria. Staphylococcus epidermidis, MRCNS (methicillin-resistant coagulase-negative staphylococci, resistant to all beta-lactam antibiotics: penicillins, penicillins with beta-lactamase inhibitor, cephalosporins and carbapenems) was the main pathogen detected (19.05%, 4/21), followed by Enterococcus faecalis (9.52%, 2/21), Enterococcus faecium (9.52%, 2/21), Staphylococcus haemolyticus, MRCNS (4.76%, 1/21), Streptococcus mitis (9.52%, 2/21), Streptococcus parasanguinis (9.52%, 2/21), Micrococcus luteus (4.76%, 1/21) and Bacillus spp. (4.76%, 1/21). The following Gram-negative bacteria were also found in the specimens examined: Escherichia coli, ESBL (extended-spectrum β-lactamase producing E. coli) (4.76%, 1/21), Escherichia coli (4.76%, 1/21), Pseudomonas aeruginosa (4.76%, 1/21), Klebsiella oxytoca (9.52%, 2/21) and Sphingomonas paucimobilis (4.76%, 1/21). Gram-positive bacteria caused nosocomial infections in nine patients with SBP, Gram-negative bacteria caused nosocomial infections in two patients. In six patients with SBP, community-acquired infections caused by Gram-negative bacteria were found in three cases, Gram-positive bacteria in two cases, and in one case, community-acquired infection was caused by mixed Gram-positive and Gram-negative. Bacteria isolated from patients with hospital-acquired SBP showed higher drug resistance than those found in patients with non-hospital SBP. Bacterial infections in cirrhotic patients with complications may be responsible for their deteriorating health. Prompt intervention is critical to reducing mortality.

Clinical Features and Genomic Epidemiology of Bloodstream Infections due to Enterococcal Species Other Than Enterococcus faecalis or E. faecium in Patients With Cancer.

Non-Enterococcus faecium, non-E. faecalis (NFF) enterococci are a heterogeneous group of clinically pathogenic enterococci that include species with intrinsic low-level vancomycin resistance. Patients with cancer are at increased risk for bacteremia with NFF enterococci, but their clinical and molecular epidemiology have not been extensively described. We conducted a retrospective review of all patients (n = 70) with NFF bacteremia from 2016 to 2022 at a major cancer center. The main outcomes assessed were 30-day mortality, microbiological failure (positive blood cultures for ≥4 days), and recurrence of bacteremia (positive blood culture <14 days after clearance). Whole-genome sequencing was performed on all available NFF (n = 65). Patients with hematological malignancies made up 56% of the cohort (77% had leukemia). The majority of solid malignancies (87%) were gastrointestinal in origin. The majority of infections (83%) originated from an intra-abdominal source. The most common NFF species were E. gallinarum (50%) and E. casseliflavus (30%). Most (61%) patients received combination therapy. Bacteremia recurred in 4.3% of patients, there was a 30-day mortality of 23%, and 4.3% had microbiological failure. E. gallinarum and E. casseliflavus isolates were genetically diverse with no spatiotemporal clustering to suggest a single strain. Frequencies of ampicillin resistance (4.3%) and daptomycin resistance (1.9%) were low. Patients with hematologic malignancy had infections with NFF enterococci that harbored more resistance genes than patients with solid malignancy (P = .005). NFF bacteremia is caused by a heterogeneous population of isolates and is associated with significant mortality. Hematological malignancy is an important risk factor for infection with NFF resistant to multiple antibiotics.

Molecular detection of enterotoxins in multidrug resistant Aeromonas from ready to eat foods in North Western Himalayas: Public health significance

Aeromonas spp. are normal inhabitants of aquatic environments and are emerging foodborne bacterial pathogens. Aeromonas spp. contamination is frequent in ready-to-eat (RTE) seafood and can also occur in products prepared from milk or meat. The study determined the enterotoxin and antimicrobial susceptibility profiles of Aeromonas spp. isolates recovered from RTE milk products (n = 105), RTE meat/fish products (n = 40) and drinking water (n = 60) samples collected from tourist places in Himachal Pradesh, India, in northwestern Himalayas. 7.3 % (16/220) samples were found contaminated with Aeromonas spp. These isolates were identified as A. hydrophila (31.3 %), A. schubertii (25.0 %), A. sobria (25.0 %) and A. veronii (18.8 %). Aeromonas spp. contamination was significantly higher (14.3 %, 15/105, p = 0.0001) in RTE milk products. The contamination levels for water samples were 1.7 % whereas none of the tested RTE meat or fish products yielded Aeromonas spp. Among RTE milk products, contamination was significantly higher in paneer (South Asian soft cheese) (26.1 %, p = 0.0027) and cream (25.0 %, p = 0.046) based RTE foods. All isolates carried alt (361 bp), encoding a cytotonic heat-labile enterotoxin. Ampicillin resistance was 100 % and high levels (>30 %) of resistance were recorded for amoxicillin/clavulanic acid, amikacin, cefotaxime and ceftazidime. Six (37.5 %) isolates were multi drug resistant (MDR), showing resistance to aminoglycosides, cephams and penicillins. Isolation of alt carrying MDR isolates from RTE foods indicates that Aeromonas spp. can be potential foodborne public health threat in northwestern Himalayas.

Trends in serotype distribution and antimicrobial susceptibility pattern of invasive Haemophilus influenzae isolates from Brazil, 2009-2021.

Invasive Haemophilus influenzae (Hi) disease poses a significant global health challenge. With the relaxation of COVID-19 pandemic measures and declining H. influenzae serotype b (Hib) vaccination coverage, there is concern about a potential increase in Hi cases worldwide. This study analyzed 1437 invasive Hi isolates in Brazil over 13years, determining capsular serotypes, antimicrobial susceptibility, and genetic relatedness through multilocus sequence typing. The primary source of isolation for these invasive H. influenzae isolates was blood (54.4%), followed by cerebrospinal fluid (37.1%) and lung specimens (8.5%), respectively. Consequently, bacteremia (47%) was the most common clinical presentation, followed by meningitis (39.6%) and pneumonia (13.4%). Non-encapsulated Hi (NTHi) predominated among the isolates (51.4%), along with serotype a (22%) and serotype b (21.5%) among the encapsulated isolates. The majority of the encapsulated isolates were isolated from children under 14years of age (76.7%), while NTHi isolates were identified in patients older than 15years, particularly those ≥ 60years old (40%). Ampicillin resistance was observed in 17.1% of cases, displaying β-lactamase production as the principal resistance mechanism. MLST revealed a diverse NTHi population, whereas the encapsulated isolates presented a clonal structure. This study describes the prevalence of NTHi isolates circulating in Brazil after two decades of the Hib vaccine immunization program. Continuous universal surveillance is crucial for implementing prompt public health measures to prevent and control invasive Hi disease and monitor changes in antibiotic resistance profiles.

Population pharmacokinetic meta-analysis of five beta-lactams antibiotics to support dosing regimens in dogs for surgical antimicrobial prophylaxis

The Pharmacokinetic/Pharmacodynamic (PK/PD) relationship of antimicrobial drugs (AMD) for surgical prophylaxis has been poorly studied, hampering evidence-based decision making around AMD dosing and timing. Our objective is to use PK/PD principles to inform (1) the timing of administration and (2) the interval for re-administration of AMD used peri-operatively in dogs. Raw plasma concentrations of cefazolin, cefuroxime, cefalexin, amoxicillin and ampicillin were retrieved from original intravenous studies performed in dogs. E. coli and methicillin-susceptible staphylococci were identified as possible intraoperative contaminants and their epidemiological cut-offs (ECOFF) were retrieved from the EUCAST database. Individual PK data were refitted with non-linear mixed effect models (Phoenix®). We performed Monte Carlo simulation to compute i) the 95th percentile of time of peak concentration in the peripheral compartment (informing timing between administration and first incision) and ii) the duration for which at least 90% of dogs maintain a free plasma concentration above ECOFF (informing timing of re-administration: 1.5–4 h). Cefazolin (22–25 mg/kg), cefuroxime (20 mg/kg), cefalexin (15 mg/kg) and amoxicillin (16.7 mg/kg) reached peak peripheral concentrations within 30 min, but ampicillin (20 mg/kg) required 82 min, respectively. For methicillin-susceptible staphylococci, cefazolin and cefuroxime require re-administration every 2 h, whereas cefalexin and both amoxicillin and ampicillin can be readministered every 3 and 4 h, respectively. For E. coli, only cefazolin provided adequate perioperative coverage with 2-hourly administration, where cefuroxime and cefalexin failed uniformly. Alternatively, ampicillin and amoxicillin (critically ill dogs) may cover E. coli contaminations, but only if readministered every 1.5 h. These PK-derived conclusions provide a rationale for perioperative AMD administration timing.

Ertapenem's therapeutic potential for Mycobacterium avium lung disease in the hollow fibre model

IntroductionGuideline-based therapy for Mycobacterium avium complex (MAC) pulmonary disease achieves sustained sputum conversion rates in only 43–53% of patients. Repurposing of β-lactam antibiotics such as ertapenem could expedite design of more efficacious regimens, compared to developing new drugs. MethodsWe performed an ertapenem exposure-response study in the hollow fibre system model of intracellular MAC (HFS-MAC). We recapitulated human-like intrapulmonary concentration-time profiles of eight once-daily intravenous doses of ertapenem over 28 days and performed repetitive sampling for drug concentration-time profiles and MAC burden. The % of time concentration persisted above MIC (%TMIC) mediating either 50% or 80% of maximal effect (E50, EC80) were identified. The EC80 was used as target exposure in a 10 000 subject Monte Carlo experiments for ertapenem doses of 1G, 2G, or 4G administered once versus twice daily. ResultsThe ertapenem MIC ranged from 0.5 to 2 mg/L on three occasions. Ertapenem achieved a half-life of 4.04 ± 0.80 h in the HFS-MAC and killed a maximum of 2.17 log10 CFU/mL below day 0. The EC50 was %TMIC of 75.9% (95% confidence interval: 68.43%–86.54%) and the EC80 was %TMIC of 100%. Target attainment probability was >90% for 1G twice daily up to an MIC of 2 mg/L, while for 2G twice daily the susceptibility MIC breakpoint was 4–8 mg/L. ConclusionsErtapenem microbial kill below day 0 burden was better than guideline-based therapy drugs in the HFS-MAC in the past. Ertapenem is a promising drug for novel combination therapies for MAC lung disease.

Reducing Peptidoglycan Crosslinking by Chemical Modulator Reverts β-lactam Resistance in Methicillin-Resistant Staphylococcus aureus.

Small molecule can be utilized to restore the effectiveness of existing major classes of antibiotics against antibiotic-resistant bacteria. In this study, it is demonstrated that celastrol, a natural compound, can modify the bacterial cell wall and subsequently render bacteria more suceptible to β-lactam antibiotics. It is shown that celastrol leads to incomplete cell wall crosslinking by modulating levels of c-di-AMP, a secondary messenger, in methicillin-resistant Staphylococcus aureus (MRSA). This mechanism enables celastrol to act as a potentiator, effectively rendering MRSA susceptible to a range of penicillins and cephalosporins. Restoration of in vivo susceptibility of MRSA to methicillin is also demonstrated using a sepsis animal model by co-administering methicillin along with celastrol at a much lower amount than that of methicillin. The results suggest a novel approach for developing potentiators for major classes of antibiotics by exploring molecules that re-program metabolic pathways to reverse β-lactam-resistant strains to susceptible strains.

Investigation of Thermodynamic and Morphological Properties of Crystalline 4-HPG (4-hydroxyphenylglycine) Using Raman, PXRD and DTA/TGA

This study focuses on the detailed physical characterization of 4-HPG, a significant impurity found in some of the most commonly prescribed β-lactam antibiotics worldwide. Various analytical techniques, including X-ray powder diffractometry, dynamic light scattering, scanning electron microscopy, Fourier-transform infrared, and Raman spectroscopy, were employed to characterize the properties of 4-HPG crystals. XRD analysis revealed the crystallinity and small crystallite sizes of 4-HPG particles, supported by DLS and SEM analyses. FT-IR and Raman spectroscopy results exhibited excellent agreement, providing insight into the structural characterization of 4-HPG. Thermal analysis revealed a two-stage degradation feature of 4-HPG. Overall, this study contributes to a better understanding of 4-HPG's structure and its impact on antibiotic stability.

Novel Siderophore Cephalosporin and Combinations of Cephalosporins with β-Lactamase Inhibitors as an Advancement in Treatment of Ventilator-Associated Pneumonia.

In an era of increasing antibiotic resistance among pathogens, the treatment options for infectious diseases are diminishing. One of the clinical groups especially vulnerable to this threat are patients who are hospitalized in intensive care units due to ventilator-associated pneumonia caused by multidrug-resistant/extensively drug-resistant Gram-negative bacteria. In order to prevent the exhaustion of therapeutic options for this life-threatening condition, there is an urgent need for new pharmaceuticals. Novel β-lactam antibiotics, including combinations of cephalosporins with β-lactamase inhibitors, are proposed as a solution to this escalating problem. The unique mechanism of action, distinctive to this new group of siderophore cephalosporins, can overcome multidrug resistance, which is raising high expectations. In this review, we present the summarized results of clinical trials, in vitro studies, and case studies on the therapeutic efficacy of cefoperazone-sulbactam, ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol in the treatment of ventilator-associated pneumonia. We demonstrate that treatment strategies based on siderophore cephalosporins and combinations of β-lactams with β-lactamases inhibitors show comparable or higher clinical efficacy than those used with classic pharmaceuticals, like carbapenems, colistin, or tigecycline, and are often associated with a lower risk of adverse events.

Chemical Profile with Antibacterial and Modulatory Activity of Extracts from the Stem Bark of Cnidoscolus quercifolius Pohl.

Objective: The present study aimed to investigate the chemical profile and evaluate the antibacterial and antibiotic-modulating activity of the methanolic extract and ethyl acetate of the stem bark of C. quercifolius against standard and multiresistant strains. Methods: The Minimum Inhibitory Concentration was determined by the microdilution method, and the modulating potential of the extracts on aminoglycoside and β-lactam antibiotics was evaluated. Results: The classes of secondary metabolites identified from qualitative chemical prospecting were flavones, flavonols, xanthones, flavonones, flavonols, catechins and leucoanthocyanidins. The assays showed inhibition only for Klebsiella pneumoniae-producing extended-spectrum β- lactamase, Klebsiella pneumoniae carbapenemase and Escherichia coli ATCC 25922 with MICs of 256, 512 and 512 μg/mL, respectively. The extracts, when associated with gentamicin and amoxicillin, showed synergism against all standard and multiresistant strains, with the exception of Klebsiella pneumoniae carbapenemase and Klebsiella pneumoniae producing extendedspectrum β-lactamase, respectively. When combined with amikacin, they also demonstrated synergism against multidrug-resistant strains; however, only the ethyl acetate extract had a synergistic effect against E. coli ATCC 25922. The association of penicillin with methanolic extract showed synergism only for Klebsiella pneumoniae producing extended-spectrum β-lactamase and S. aureus ATCC 29213, while the ethyl acetate extracts demonstrated synergism against S. aureus and Klebsiella pneumoniae producing extended-spectrum β-lactamase. Conclusion: It was found that C. quercifolius extracts have antibacterial potential against gramnegative bacteria. However, the need for additional research using specific methods against bacteria carrying different resistance mechanisms, especially gram-positive ones, is highlighted, with the aim of elucidating their mechanism of action. conclusion: The species was found to have substances with potential against Gram-negative bacteria. However, the need for additional research using specific methods against bacteria carrying different resistance mechanisms, especially Gram-positive ones, is highlighted, with the aim of elucidating their mechanism of action.

Analysis of Antibiotics in Milk from Smallholder Farmers from Kenya Shows Traces Above the Recommended Maximum Residue Limits

Antimicrobial resistance (AMR) is rising globally and is likely to cause more deaths because of antibiotic-resistant microbial infections and antibiotic residues in animal foods and products as a result of misuse of antibiotics in dairying. Thus, we determined the presence and quantities of sulfonamide, tetracycline, and beta-lactam drug residues in milk sampled in Nyandarua, Meru, and Kiambu counties in Kenya using the Charm TRIO® test kit and liquid chromatography (LC) coupled to the triple quadrupole mass spectroscopy (MS) (LC-MS/MS). The TRIO® test kit showed dicloxacillin as the most prevalent at 9.3%, followed by penicillin and cloxacillin at 3.7% each, and nafcillin at 0.9% among the beta-lactams. Among the tetracyclines, demeclocycline and tigecycline were the most prevalent at 10.3% each, followed by oxytetracycline at 9.3%, chlortetracycline at 7.5%, and doxycycline at 3.7%, while sulfaquinoxaline was the only sulfonamide drug detected at 4%. The LC-MS/MS detected the presence of all the tested β-lactam and tetracycline antimicrobial traces and all sulfonamide drugs except sulfamerazine in all three counties. All the tetracycline antibiotics recorded between 3 and 10.5% of antibiotic residues above the recommended Maximum Residue Levels (MRLs) in milk across all three counties, with beta-lactam antibiotics recording between 2 and 33.3%, indicating their misuse in the three counties. Sulfaquinoxaline was the only sulfonamide detected in milk samples above the recommended MRLs, indicating sulfonamides are less used in those counties. Therefore, it is important to enforce a regulatory framework to control antibiotic use in livestock to minimize potential health risks related to their traces in the foods.