Erythromycin Research Articles

Commonly Used Therapeutics Associated with Changes in Arousal Inhibit GABAAR Activation.

GABAA receptor-positive modulators are well-known to induce sedation, sleep, and general anesthesia. Conversely, GABAA receptor negative allosteric modulators (GABAARNAMs) can increase arousal and induce seizures. Motivated by our studies with patients with hypersomnia, and our discovery that two GABAARNAMs can restore the Excitation/Inhibition (E/I) balance in vitro and arousal in vivo, we chose to screen 11 compounds that have been reported to modulate arousal, to see if they shared a GABA-related mechanism. We determined modulation with both conventional and microfluidic patch clamp methods. We found that receptor activation was variably modulated by all 11 compounds: Rifampicin (RIF), Metronidazole (MET), Minocycline (MIN), Erythromycin (ERY), Ofloxacin (OFX), Chloroquine (CQ), Hydroxychloroquine sulfate (HCQ), Flumazenil (FLZ), Pentylenetetrazol (PTZ), (-)-Epigallocatechin Gallate (EGCG), and clarithromycin (CLR). The computational modeling of modulator-receptor interactions predicted drug action at canonical binding sites and novel orphan sites on the receptor. Our findings suggest that multiple avenues of investigation are now open to investigate large and brain-penetrant molecules for the treatment of patients with diminished CNS E/I balance.

Preparation of composite nanofiltration membrane with interlayer for pharmaceutical rejection

It is necessary to prepare a nanofiltration (NF) membrane with high water permeability and excellent pharmaceutical selectivity. In this study, polydopamine/poly(sulfobetaine methacrylate) (PDA/PSBMA) was selected as the interlayer to improve the water permeance of polyamide (PA) composite NF membrane. The introduction of the PDA/PSBMA interlayer led to an increase in the degree of crosslinking of the PA layer and the formation of cracks inside and below the PA layer. As a result, a negatively charged NF membrane with a molecular weight cut-off (MWCO) of 348 Da and an average pore size of 0.23 nm was obtained. The pure water permeance of the optimal NF membrane was 22.0 L·m−2·h−1·bar−1, and the Na2SO4 rejection was 98.9%. Meanwhile, this NF membrane showed excellent rejection of antibiotics. The rejections of erythromycin (ERY), tetracycline hydrochloride (TC), and cephalexin (CA) were 100.0%, 99.4%, and 97.5%, respectively. The separation coefficients of NaCl/TC and NaCl/ERY were as high as 108.2 and 80.8, respectively. In addition, this NF membrane demonstrated outstanding properties in terms of antifouling and long-term stability. The NF membrane with PDA/PSBMA interlayer has excellent potential for pharmaceutical wastewater treatment and antibiotic extraction.

Distribution of Multidrug-Resistant Invasive Serotypes of Streptococcus pneumoniae during the Period 2007-2021 in Madrid, Spain.

After the systematic use of conjugate vaccines, the invasive pneumococcal disease (IPD) was included into the Madrid Notifiable Diseases Surveillance System through an Epidemiological Surveillance Network. Furthermore, Streptococcus pneumoniae was included in the Spanish Plan of Antibiotic Resistance. The aim of this study was to analyse the multidrug-resistant (MDR) phenotype distribution among invasive strains of Streptococcus pneumoniae isolated during 2007-2021 from usually sterile clinical samples in Madrid, Spain. A total number of 7133 invasive pneumococcal isolates were studied during the period from February 2007 to December 2021. Serotyping was characterised using the Pneumotest-Latex and by the Quellung reaction. Antibiotic susceptibility testing to penicillin (PEN), erythromycin (ERY), and levofloxacin (LVX) was performed using the E-test according to the EUCAST guidelines and breakpoints. Combination of non-susceptibility to PEN at standard dosing regimen (PNSSDR), resistance to ERY (ERYR) and to LVX (LVXR) was considered to be multidrug-resistant at standard dosing regimen of penicillin (MRPSDR), whereas the combination of resistance to PEN (PENR), ERYR, and LVXR was considered multidrug-resistant (MDR). The number of MDRPSDR and or MDR strains in the entire population (n = 7133) during the complete period (2007-2021) were 51 (0.7%) and 6 (0.1%), respectively. All MDRPSDR and/or MDR strains belonged to nine serotypes: 19A (n = 13), 15A (n = 12), 9V (n = 12), 14 (n = 7), 24F (n = 3), 15F (n = 1), 19F (n = 1), 6B (n = 1) and 6C (n = 1). Only two serotypes (9V and 19A) were found among MDR strains, and most of them (5/6) belonged to serotype 9V. Only 12.4% of the strains typified as serotype 9V were MDRPSDR and only 5.2% as MDR. The levels of pneumococcal MDRPSDR and/or MDR in this study were low and all six MDR strains were isolated between 2014 and 2018. These results reinforce the importance of monitoring the evolution of non-susceptible serotypes including those with MDR in the coming years, especially after the introduction of new conjugate vaccines of a broader spectrum.

Prediction of pharmaceuticals removal in activated sludge system under different operational parameters using an extended ASM-PhACs model

Removal of pharmaceuticals is essential in wastewater treatment systems due to their release and accumulation in the environment, which are raising issues for the environment and human health. A mathematical model could be used to predict pharmaceuticals removal under various operational parameters and assess the contributions of different removal pathways to pharmaceuticals removal. Here an ASM-PhACs model was established to describe pharmaceuticals removal including diclofenac (DCF), erythromycin (ERY), gemfibrozil (GEM) and carbamazepine (CBZ) removal in activated sludge system. The pharmaceuticals removal processes linked to co-metabolic biodegradation through the growth of ammonia oxidizing bacteria (AOB), metabolic biodegradation through AOB, metabolic biodegradation through heterotrophic bacteria (HB) and sludge adsorption were incorporated into activated sludge model (ASM1) framework. The kinetic equations were established for each pharmaceuticals removal process. To provide the experimental data for model calibration and validation, two sets of batch tests were designed and conducted in the laboratory scale using SBR technology. According to the batch test data and results of sensitivity analysis, the newly added parameters and some original default parameters affecting pharmaceuticals removal processes were screened and calibrated. The model could accurately simulate all the dynamics of chemical oxygen demand, nitrogen and pharmaceuticals under various conditions. To explore the effect of operational parameters on pharmaceuticals removal efficiency, the wide range of operational parameters was analyzed during model simulation. According to the simulation results, both influent NH4+-N concentration and DO were found to be the significant parameters that impact the removal of DCF, ERY and GEM. AOB biodegradation played an important role in DCF, ERY and GEM removal. The developed model framework helps to investigate the removal mechanisms and key influencing factors of pharmaceuticals removal, thus providing guidelines for reactor design, operation and optimization aiming at pharmaceuticals removal.

Development and Optimization of Erythromycin Loaded Transethosomes Cinnamon Oil Based Emulgel for Antimicrobial Efficiency

Erythromycin (EM) is a macrolide antibiotic that is frequently used to treat skin bacterial infections. It has a short half-life (1-1.5 h), instability in stomach pH, and a low oral bioavailability. These foregoing factors limit its oral application; therefore, the development of topical formulations loaded with erythromycin is an essential point to maximize the drug's concentration at the skin. Accordingly, the current study's goal was to boost the antimicrobial activity of EM by utilizing the advantages of natural oils such as cinnamon oil. Erythromycin-loaded transethosomes (EM-TE) were generated and optimized using a Box-Behnken design employing, phospholipid concentration (A), surfactant concentration (B), and ethanol content (C) as independent variables. Their effects on entrapment efficiency, EE, (Y1) and the total amount of erythromycin that penetrated the skin after 6 h, Q6h (Y2), were assessed. The optimized transethosome showed a particle size of 256.2 nm, EE of 67.96 ± 0.59%, and Q6h of 665.96 ± 5.87 (µg/cm2) after 6 h. The TEM analysis revealed that, the vesicles are well-known packed structures with a spherical shape. The optimized transethosomes formulation was further transformed into a cinnamon oil-based emulgel system using HPMC as a gelling agent. The generated EM-TE-emulgel was characterized by its physical features, in vitro, ex vivo studies, and antimicrobial activities. The formulation showed sufficient characteristics for effective topical application, and demonstrated a great stability. Additionally, EM-TE-Emulgel had the highest transdermal flux (120.19 μg/cm2·h), and showed considerably (p < 0.05) greater antimicrobial activity, than EM-TE-gel and placebo TE-Emulgel. The action of EM was subsequently augmented with cinnamon oil, which eventually showed a notable effect against bacterial growth. Finally, these results demonstrate that the transethosomes-loaded cinnamon oil-based emulgel is an alternative way to deliver erythromycin for the treatment of topical bacterial infections.

Use of a product based on wood vinegar of Eucalyptus clone I144 used in the control of bovine mastitis

Bovine mastitis is one of the most frequent diseases in dairy cattle worldwide. The use of antiseptics in milking, if properly used, can lead to a reduction in potentially pathogenic microorganisms and their transmission between herds. Several medicinal plants have antiseptic potential, including eucalyptus (Eucalyptus spp.). Therefore, the objective of this study was to evaluate the effectiveness of wood vinegar from Eucalyptus urograndis clone GG I144 (EU) as an antiseptic in vitro and in vivo; in addition, to its cytotoxicity and antimicrobial resistance. Fifteen bovines were used, lactating females 3–6 years of age and divided into three groups of five animals each. The wood vinegar was placed in the teats of the animal for 28 days and collections of cellular debris were performed every 7 days. At the Veterinary Microbiology Laboratory (LAMIV) of UFERSA, the samples were processed and serial dilution was performed in Petri plates with plate count agar (PCA) at 37 °C. Cytotoxicity was verified based on morphological alterations and metabolic activity. Morphological changes were not observed in all cells incubated with 1 % pyroligneous extract. The in vitro data demonstrated antimicrobial activity against S. aureus, S. agalactiae, Salmonella, E. coli and P. aeruginosa. The bacteria of the genus Staphylococcus and Corynebacterium were resistant to penicillin (PEN), rifampicin (RIF), nitrofurantoin (NIT), erythromycin (ERI), and ciprofloxacin (CIP). The extract was used in vivo in the post-dipping of dairy cows, which reduced the microbiological load present in the mammary glands from 4.74 to 2.54 CFU, indicating its future use as an antiseptic.

Investigating the potential anticancer activities of antibiotics as topoisomerase II inhibitors and DNA intercalators: in vitro, molecular docking, molecular dynamics, and SAR studies

Topoisomerase II (TOP-2) is a promising molecular target for cancer therapy. Numerous antibiotics could interact with biologically relevant macromolecules and provoke antitumor potential. Herein, molecular docking studies were used to investigate the binding interactions of 138 antibiotics against the human topoisomerase II-DNA complex. Followed by the MD simulations for 200 ns and MM-GBSA calculations. On the other hand, the antitumor activities of the most promising candidates were investigated against three cancer cell lines using doxorubicin (DOX) as a reference drug. Notably, spiramycin (SP) and clarithromycin (CL) showed promising anticancer potentials on the MCF-7 cell line. Moreover, azithromycin (AZ) and CL exhibited good anticancer potentials against the HCT-116 cell line. Finally, the TOP-2 enzyme inhibition assay was carried out to confirm the proposed rationale. Briefly, potent TOP-2 inhibitory potentials were recorded for erythromycin (ER) and roxithromycin (RO). Additionally, a SAR study opened eyes to promising anticancer pharmacophores encountered by these antibiotics. Highlights Molecular docking studies of 139 antibiotics against the topoisomerase II-DNA complex. SP, RO, AZ, CL, and ER were the most promising and commercially available candidates. Molecular dynamics simulations for 200 ns for the most promising five complexes. MM-GBSA calculations for the frontier five complexes. SP and CL showed promising anticancer potentials on the MCF-7 cell line, besides, AZ and CL exhibited good anticancer potentials against the HCT-116 cell line. Potent TOP-2 inhibitory potentials were recorded for ER and RO.

Adsorption of antibiotics from wastewater by cabbage-based N, P co-doped mesoporous carbon materials

Research on low-polluting, economical, and reliable antibiotic adsorption materials is of great significance for reducing pollution in the pharmaceutical and aquaculture industries. Herein, N, P co-doped carbon material (PCC500) with a high specific surface area of 1400 m2/g and a high mesoporous ratio of 89.9% were prepared from cabbage waste by H3PO4 hydrothermal combined with activation. PCC500 showed good adsorption performance for various antibiotics, including chloramphenicol (CHL), tetracycline (TC), ofloxacin (OFX) and erythromycin (ERY). 99% removal efficiency and 247 mg/g adsorption capacity of TC on PCC500 were obtained at 298 K (C0 = 50 mg/L), and 471 mg/g of the maximum adsorption capacity of was achieved at 318 K. The adsorption kinetics and thermodynamic analysis indicated that there was chemisorption during the adsorption process. A series of characterizations including SEM, EDS, N2 adsorption and desorption, FTIR, XPS showed that the abundant pore structure and P, N functional groups are important factors affecting the adsorption performance, and the graphite-N and C3-PO structures in PCC500 could be the important active sites responsible for antibiotic chemisorption. Moreover, PCC500 exhibits good resistance to impurity ions and cyclic stability.

The Study of Antibacterial Effects of Combining Some Medicinal Plants with Certain Antibiotics Against the Multidrug-Resistant E. coli.

As resistant microorganisms are causing a serious global problem, medicinal plants had begun to draw scientists' attention to use them as alternative medicines or in case of this research; to be combined with antibiotics to find a solution against one of these resistant microorganisms. This research shows the possibility of getting positive results in inhibiting the growth of Multidrug-resistant E. coli; through the synergism between medicinal plant extracts with antibiotics. Each of the alcoholic and aqueous extract of the plants: Glycyrrhiza glabra, Viscum album and Chamaemelum nobile were combined with Erythromycin ethylsuccinate and Gramicidin in certain percentages individually to get three types of combinations (A, B and C). Combinations that contained more percentages of extracts than antibiotic in them showed the highest synergistic positive results in inhibiting the growth of E. coli. Furthermore, these plant extracts as the phytochemical screening tests showed, contain certain active contents which in rule have antimicrobial effects.

Predation risk affects the ecotoxicity evaluation of antibiotics: Population growth and antioxidase activity in the ciliate Paramecium jenningsi

Although predation risk exists under natural conditions, its role is usually ignored when evaluating the ecotoxicity of environmental contaminants, and the interaction between predation risk and antibiotic ecotoxicity is not yet clear. To investigate the nonconsumptive effects (NCEs) of predation on the ecotoxicity evaluation of antibiotics, the median lethal concentration (LC50), relative population growth rate (RGR), and activities of three antioxidases were measured in the ciliate Paramecium jenningsi exposed to graded concentrations of the antibiotics nitrofurazone (NFZ) or erythromycin (ERY) in the presence or absence of a predator, i.e., the ciliate Didinium nasutum. The results showed that (1) NCEs significantly reduced the LC50 of NFZ but had no effect on that of ERY; (2) predation pressure alone had no significant effect on the inhibitory rate of the P. jenningsi population, but the interaction with NFZ was synergistic, while that with CRY was additive; (3) the concentrationresponse (i.e., mortality) model for each antibiotic exposure with and without predation pressure differed significantly in the parameter slope; (4) RGRs were significantly reduced by antibiotic exposure or NCEs; only in NFZ-exposed groups did the RGRs decrease linearly with increasing exposure concentration; and (5) the activities of all three antioxidases significantly increased due to NCEs or following exposure to antibiotics. In brief, NCEs were detected in P. jenningsi, and these had additive or synergistic effects on antibiotic ecotoxicity, but their magnitude depended on the properties and exposure concentrations of the antibiotics. Our findings suggest that it is necessary to consider the roles of NCEs in the ecotoxicity evaluation of environmental contaminants.

Pharmacokinetics, PK/PD analysis and placental transfer of erythromycin administered to pregnant goats

The aims of the present study were i) to characterize the pharmacokinetic of erythromycin (ERY) after intravenous (IV) and intramuscular (IM) administration to pregnant goats, ii) to make a PK/PD analysis by Monte Carlo simulation from steady-state pharmacokinetic parameters of ERY by IV and IM routes considering sensitivity of coagulase negative staphylococci isolate of milk of goats, and iii) to determine the placental transfer of the drug after intravenous maternal administration. Six pregnant goats (87–89 days of pregnancy) received ERY by the IV (10 mg/kg) and the IM (15 mg/kg) routes of administration. Blood samples were collected at predetermined times. The same animals (145–147 days of pregnancy) received a 10 mg/kg dose of erythromycin by IV route of administration and underwent a cesarean surgery; blood venous fetal and maternal samples were collected. ERY concentrations were determined by microbiological assay. MIC of one hundred and twenty seven coagulase negative staphylococci isolated from goats was determined by broth macrodilution method. ERY showed a wide distribution with low serum concentrations after IV and a high bioavailability after IM administration. PK/PD analysis by Monte Carlo simulation indicates that 15 mg/kg every 8 h IM administration of ERY in pregnant goats may be adequate for sensitive microorganisms with MIC ≤ 0.25 µg/mL. However, 10 mg/kg IV showed that does not meet the objective even for strains with MIC ≤ 0.125 µg/mL. Placental transfer of ERY was low (Concentrationfetus/Concentrationmother = 0.10).

Epsilon-poly-l-lysine conjugated erythromycin for enhanced antibiotic therapy.

Antibiotic resistance is a big threat to public health. How to improve the therapeutic efficacy of conventional antibiotics is an effective way to address this issue. In order to enhance the antibacterial activity of conventional antibiotic erythromycin (EM), EM is conjugated to positively charged ε-poly-l-lysine (EPL) to obtain EPL modified EM (EPL-EM). The grafting ratio of EM can be calculated from the 1H NMR spectrum. EPL-EM is stable in physiological environment, while EM can be readily released from EPL-EM upon incubating with esterase which can be secreted by most bacteria. Because of the presence of cationic EPL, EPL-EM showed much stronger antibacterial activity than free EM, with much lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Moreover, compared to free EM, the development of drug resistance can be slowed down if EPL-EM is used, which can be ascribed to the reduction of EM dosage. Meanwhile, EPL-EM cannot induce hemolysis and cytotoxicity, which indicates that EPL-EM exhibits excellent biocompatibility. The design of EPL-EM with enhanced antibacterial activity and excellent biocompatibility provides an innovative way to combat antibiotic resistance.

Influence of metabolism and microbiology on organic micropollutants biotransformation in anoxic heterotrophic reactors.

There is scarce information about the biotransformation of organic micropollutants (OMPs) under anoxic conditions. In this study, a heterotrophic denitrifying bioreactor was set up to study the fate of several OMPs from metabolic and microbiological points of view. Primary metabolic activity was increased by adding progressively higher nitrogen loading rates during the operation (from 0.075 to 0.4gN-NO3- L-1 d-1), which resulted in an important shift in the microbial population from a specialized biomass to a more diverse community. Such a change provoked a significant increase in the removal efficiency of erythromycin (ERY), roxithromycin (ROX) and bisphenol-A (BPA), and some bacterial taxa, such as Rhodoplanes, were identified as possible indicators related to the biodegradation of these compounds. The increasing primary metabolic activity in the reactor did not enhance the OMP-specific removal rates, suggesting that the bacterial composition is more influential than cometabolism.

DETERMINATION OF ANTIBIOTIC RESIDUES IN COW MILK BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHOD

Antibiotics are used as growth boosters, illness prevention and treatment in animal agriculture. The majority of cattle farmers take advantage of the system and do not adhere to the withdrawal periods. These antibiotics are identified as residues in ready-to-eat meat, causing negative consequences in human beings. The majority of the study on determining antibiotic residues in ready-to-eat meat relied on thorough research and paid little attention to animal products such as cow milk. The goal of this study was to use a method that could be used on a regular basis to determine the amounts of antibiotic residues in cow milk marketed to the general population in Ibadan. These antibiotics residues (chloramphenicol and erythromycin) were extracted from cow milk by centrifugation and liquid-liquid extraction using acetonitrile. Vacuum-liquid chromatography was used to clean the extracts, and 10mL of a 1:1:1 v/v mixture of n-hexane, chloroform, and methanol was used. After that, a high-resolution liquid chromatography analysis was performed on the extracts. All of the samples included residues of chloramphenicol (CAP), with mean values ranging from 91.4610.89 to 692.6616.74 ng/g, while erythromycin (ERY) was not observed. All of the samples contained chloramphenicol, proving that cow farmers had been abusing it.&#x0D;

Isolation of multidrug-resistant Escherichia coli and Salmonella spp. from sulfonamide-treated diarrheic calves.

The bovine industry is threatened by one of the most serious and deadly enteric diseases, calf diarrhea, particularly in developing nations like Bangladesh. In this context, bacterial resistance to antimicrobial drugs and its detrimental consequences have become a critical public health issue that is difficult to address globally. This study aimed to isolate and identify Escherichia coli and Salmonella spp. with their antibiogram and antibiotic resistance gene detection from sulfonamide-treated diarrheic calves. Twelve diarrheic calves suffering from calf diarrhea in a dairy farm were selected and a total of 36 fecal samples were aseptically collected directly from rectum before, during, and at the end of treatment for each calf to determine the total viable count, total E. coli count and total Salmonella count. A polymerase chain reaction was used for the specific detection of E. coli and Salmonella genus targeting fliC and invA genes, respectively. Antibiotic sensitivity test of the isolated E. coli and Salmonella spp. were performed by the disk diffusion method for eight commonly used antibiotics. A total of 36 E. coli (100%) and 12 Salmonella spp. (33%) were isolated from the samples and were confirmed by polymerase chain reaction. Total viable count was found to be ranged from 35 × 107 to 99 × 1010 colony-forming unit (CFU)/g fecal sample before starting sulfonamide treatment, 34 × 105 to 25 × 1010 CFU/g during treatment with sulfonamide, and 48 × 103 to 69 × 1010 CFU/g immediately after completion of sulfonamide treatment. Total E. coli count was found to be ranged from 4 × 104 to 36 × 1010 CFU/g, 24 × 104 to 23 × 108 CFU/g, and 13 × 104 to 85 × 1010 CFU/g, whereas total Salmonella count was found to be ranged from 16 × 106 to 18.5 × 1011 CFU/g, 15 × 104 to 44 × 107 CFU/g, and 13.2 × 105 to 21 × 1010 CFU/g fecal sample before starting sulfonamide treatment, during treatment with sulfonamide immediately after completion of sulfonamide treatment, respectively. The in vitro antibiotic sensitivity test showed that all the E. coli and Salmonella spp. isolated from diarrheic calves (100%) contained multidrug-resistant (MDR) phenotypes. Escherichia coli isolates were found 100% resistant to amoxicillin (AMX), cefuroxime, cephalexin (CN), erythromycin (ERY), and tetracycline (TET); whereas 94.4%, 86.1%, and 77.8% isolates were resistant to doxycycline (DOX), moxifloxacin (MOF), and gentamycin (GEN), respectively. In case of Salmonella isolates, all were found 100% resistant to AMX, CN, and ERY; whereas 91.7% of resistance was observed for DOX, MOF, cefuroxime, GEN, and TET. Based on the molecular screening of the antibiotic resistance genes, tetA gene was present in 83.3% of the isolated E. coli and 75% of the isolated Salmonella strains, whereas 83.3% E. coli and 79.2% Salmonella isolates contained blaTEM gene. These findings suggest that MDR E. coli and Salmonella spp. might be responsible for calf scouring, which is challenging to treat with antibiotics or sulfonamide drugs alone. Therefore, it is important to check the antibiotic sensitivity pattern to select a suitable antibiotic for the treatment of calf scoring. A suitable antibiotic or combination of an antibiotic and sulfonamide could be effective against E. coli and Salmonella spp. responsible for calf scouring.

1321. Increased Prevalence of Group A Streptococcus (GAS) High Level Macrolide Resistance During the COVID-19 Pandemic

Abstract Background COVID-19 affected the epidemiology of many respiratory pathogens including GAS. Assessing genetic heterogeneity (emm type, antimicrobial resistance, virulence factors) can inform treatment recommendations and targets for potential GAS vaccines. We assessed GAS clinical antibiotic susceptibility and performed whole genome sequencing (WGS) among pediatric pharyngeal isolates from 2020–2022. Methods From 1/2020–3/2022 we collected throat swabs in pediatric clinics and EDs from children aged 3-18 years in Chicago, IL; Atlanta, GA; Portland, OR; and Phoenix, AZ: 1) with acute GAS pharyngitis and 2) among a convenience sample of asymptomatic children to assess for GAS colonization. Swabs were plated on blood agar. E-tests were used to assess clinical susceptibility to erythromycin (ERY) and ciprofloxacin (CIP). emm type and antimicrobial resistance genes (ERY, Clindamycin (CLI), and fluoroquinolones) were assessed by WGS. Results 1144 pharyngeal swabs were collected: 359/684 (52%) from children with GAS pharyngitis by rapid test and 20/460 (4.3%) from asymptomatic children yielded GAS on culture. Phenotypic resistance: 55/364 (15%) tested isolates were ERY resistant and 5/364 (1.4%) CIP resistant. The proportion of isolates with ERY resistance increased significantly from 2020 (6%) to 2021–2022 (25%) (χ2 = 23.70, p&amp;lt; .00001) (Figure 1). MICs were high among ERY resistant GAS (Table 1). Genotypic resistance: Of 304 sequenced GAS isolates 40/304 (13%) were ERY resistant, 35/304 (11.5%) were both ERY resistant and CLI (inducible or constitutive) resistant, and 4/304 (1.3%) fluoroquinolone resistant. ermB (62%) was the most common gene for ERY resistance and constitutive CLI resistance, followed by ermTR (23%) and ermT (11%) both conferring inducible CLI resistance. Among the 20 isolates from asymptomatic children no ERY, CLI, or CIP resistance occurred, and no resistance genes were identified. emm types 11, 9, 77, 58 and 94 were associated with ERY and CLI resistance. Conclusion ERY resistance increased from 2020–2022. The high rate of CLI resistance among ERY resistant GAS was associated with erm genes. These results are important to inform treatment recommendations for GAS pharyngitis and targets for vaccine development that can reduce antimicrobial-resistant GAS disease. Disclosures All Authors: No reported disclosures.

Green Nanoemulsion Water/Ethanol/Transcutol/LabM-Based Treatment of Pharmaceutical Antibiotic Erythromycin-Contaminated Aqueous Bulk Solution.

Contaminated wastewater released from hospital, domestic, and industrial sources is a major challenge to aquatic animals and human health. In this study, we addressed removal of erythromycin (ERN) from contaminated water employing water/ethanol/Transcutol/Labrafil M 1944 CS (LabM) green nanoemulsions as a nanocarrier system. ERN is a major antibiotic contaminant harming aquatic and human lives. Green nanoemulsions were prepared and evaluated for size, size distribution (measuring polydispersity index), stability, zeta potential, refractive index, and viscosity. Transmission electron microscopy (TEM) was used to visualize morphological behavior. The treated-water was analyzed for ERN by the spectroscopy, scanning electron microscopy-energy-dispersive X-ray analysis mode (SEM-EDX), and inductively coupled plasma-optical emission spectroscopy (ICP-OES) techniques. We studied factors (composition, size, viscosity, and time of exposure) affecting removal efficiency (%RE). The obtained green nanoemulsions (ENE1-ENE5) were stable and clear (<180 nm). ENE5 had the smallest size (58 nm), a low polydispersity index value (0.19), optimal viscosity (∼121.7 cP), and a high negative zeta potential value (-25.4 mV). A high %RE value (98.8%) was achieved with a reduced size, a high water amount, a low Capryol 90 content, and optimal viscosity as evidenced by the obtained results. Moreover, contact time had insignificant effect on %RE. UV-vis spectroscopy, SEM-EDX, and ICP-OES confirmed the absence of ERN from the treated water. Conclusively, ERN can easily be removed from polluted water employing green nanoemulsions prepared from the optimized excipients, and evaluated characteristics.

Adsorption and competition mechanism of tetracycline and erythromycin on montmorillonite: experimental and theoretical investigation

Concerns about antibiotic contamination have grown dramatically. Based on batch adsorption equilibrium experiments, the adsorption properties and mechanisms of two antibiotics, namely Tetracycline (TC) and erythromycin (ERY), on the typical clay montmorillonite (Mt) were investigated in single and binary systems. Results indicated that the adsorption of both antibiotics on Mt was a multistage process control and charge-limited intercalation. It was also clearly demonstrated the presence of the competitive adsorption between TC and ERY on the active sites of Mt. Moreover, the site energy theory and electrostatic potential (ESP) distribution were used to quantify the adsorption sites, interaction force and electrostatic attraction between Mt and antibiotics, elucidating that TC had a relatively strong competitiveness than ERY. Additionally, combined with FT-IR, XRD and molecular simulation, the adsorption process was simulated to investigate the conformational behavior of antibiotics in the confined space of Mt. These results and methodologies can aid to further study the migration-transformation of antibiotics in the environment.

Antibiotic Toxicity Isolated and as Binary Mixture to Freshwater Algae Raphidocelis subcapitata: Growth Inhibition, Prediction Model, and Environmental Risk Assessment.

Antibiotics in aqueous environments can have extremely adverse effects on non-targeted organisms. However, many research projects have only focused on the toxicological evaluation of individual antibiotics in various environments. In the present work, individual and binary mixture toxicity experiments have been conducted with the model organism Raphidocelis subcapitata (R. subcapitata), and a mixture concentration-response curve was established and contrasted with the estimated effects on the basis of both the concentration addition (CA) and the independent action (IA) models. In addition, different risk assessment methods were used and compared to evaluate the environmental risk of binary mixtures. The toxic ranking of the selected antibiotics to R. subcapitata was erythromycin (ERY) &gt; sulfamethoxazole (SMX) &gt; sulfamethazine (SMZ). In general, the conclusion of this study is that the adverse effects of binary mixtures are higher than the individual antibiotics. The CA model and RQSTU are more suitable for toxicity prediction and risk assessment of binary mixtures. This study reveals the potential ecological risks that antibiotics and their mixtures may pose to water ecosystems, thus providing scientific information for environmental quality regulation.

Campylobacter spp. isolated from poultry in Iran: Antibiotic resistance profiles, virulence genes, and molecular mechanisms.

Campylobacter spp. genera is one of the most common causes of microbial enteritis worldwide. The objective of this work was to investigate the antimicrobial resistance (AMR) patterns, virulence genes, and genetic variation of thermophilic Campylobacter species collected from chicken meat samples in Iran. A total of 255 meat specimens were taken and transferred to the laboratory. Culture methods were utilized to identify the Campylobacter genus, and PCR and sequencing were performed to confirm the organisms. Antimicrobial susceptibility evaluation was performed using broth microdilution for six antimicrobials [ciprofloxacin (CIP), nalidixic acid (NAL), sitafloxacin (SIT), erythromycin (ERY), tetracycline (TET), and gentamicin (GEN)]. By using PCR, AMR and virulence genes were detected. The detection rate of Campylobacter spp. was 64 (25.09%) out of 255 meat samples, with C.jejuni and C.coli accounting for 41 (64.06%) and 14 (21.87%), respectively. Other Campylobacter isolates accounted for 14.06% of the total (nine samples). The antibiotic susceptibility of all Campylobacter isolates was tested using six antibiotics, and all (100%) were resistant to CIP and NAL. However, TET resistance was observed in 93.9% and 83.3% of C.jejuni and C.coli isolates, respectively. Four (8.2%) C.jejuni isolates were multidrug-resistant (MDR), while none of the C.coli isolates were MDR. Two of the four MDR isolates were resistant to CIP, NAL, TET, and ERY, whereas the other two isolates were resistant to CIP, NAL, TET, and GEN. The values of the Minimum Inhibitory Concentration (MIC) were as follows: CIP, 64-256 μg/ml; NAL, 128-512 μg/ml; TET, 2-1024 μg/ml; SIT, 0.25-1μg/ml; ERY, 1-32 μg/ml; and GEN, 1-256 μg/ml. recR, dnaJ, cdtC, cdtB, cdtA, flaA, ciaB, cadF, and pidA were discovered in more than 50% of C.jejuni isolates, although wlaN, virbll, cgtB, and ceuE were found in <50%. flaA, cadF, pidA, and ciaB were discovered in more than 50% of the C.coli samples, whereas recR, cdtC, cdtB, cdtA, and cgtB were found in less than half. For C.coli, the percentages for wlaN, dnaJ, virbll, and ceuE were all zero. The results of this study show Campylobacter isolates obtained from poultry have higher resistance to quinolones and TET, pathogenicity potential, and varied genotypes.