Synergistic effects of sulopenem in combination with cefuroxime or durlobactam against Mycobacterium abscessus.

Mycobacterium abscessus (Mab) affects patients with immunosuppression or underlying structural lung diseases such as cystic fibrosis (CF). Additionally, Mab poses clinical challenges due to its resistance to multiple antibiotics. Herein, we investigated the synergistic effect of dual ß-lactams [sulopenem and cefuroxime (CXM)] or the combination of sulopenem and CXM with ß-lactamase inhibitors [BLIs-avibactam (AVI) or durlobactam (DUR)]. The sulopenem-CXM combination yielded low minimum inhibitory concentration (MIC) values for 54 clinical Mab isolates and ATCC19977 (MIC50 and MIC90 ≤0.25 µg/mL). Similar synergistic effects were observed in time-kill studies conducted at concentrations achievable in clinical settings. Sulopenem-CXM outperformed monotherapy, yielding ~1.5 Log10 CFU/mL reduction during 10 days. Addition of BLIs enhanced this antibacterial effect, resulting in an additional reduction of CFUs (~3 Log10 for sulopenem-CXM and AVI and ~4 Log10 for sulopenem-DUR). Exploration of the potential mechanisms of the synergy focused on their interactions with L,D-transpeptidases (Ldts; LdtMab1-LdtMab4), penicillin-binding-protein B (PBP B), and D,D-carboxypeptidase (DDC). Acyl complexes, identified via mass spectrometry analysis, demonstrated the binding of sulopenem with LdtMab2-LdtMab4, DDC, and PBP B and CXM with LdtMab2 and PBP B. Molecular docking and mass spectrometry data suggest the formation of a covalent adduct between sulopenem and LdtMab2 after the nucleophilic attack of the cysteine residue at the ß-lactam carbonyl carbon, leading to the cleavage of the ß-lactam ring and the establishment of a thioester bond linking the LdtMab2 with sulopenem. In conclusion, we demonstrated the biochemical basis of the synergy of sulopenem-CXM with or without BLIs. These findings potentially broaden the selection of oral therapeutic agents to combat Mab. IMPORTANCE: Treating infections from Mycobacterium abscessus (Mab), particularly those resistant to common antibiotics like macrolides, is notoriously difficult, akin to a never-ending struggle for healthcare providers. The rate of treatment failure is even higher than that seen with multidrug-resistant tuberculosis. The role of combination ß-lactams in inhibiting L,D-transpeptidation, the major peptidoglycan crosslink reaction in Mab, is an area of intense investigation, and clinicians have utilized this approach in the treatment of macrolide-resistant Mab, with reports showing clinical success. In our study, we found that cefuroxime and sulopenem, when used together, display a significant synergistic effect. If this promising result seen in lab settings, translates well into real-world clinical effectiveness, it could revolutionize current treatment methods. This combination could either replace the need for more complex intravenous medications or serve as a "step down" to an oral medication regimen. Such a shift would be much easier for patients to manage, enhancing their comfort and likelihood of sticking to the treatment plan, which could lead to better outcomes in tackling these tough infections. Our research delved into how these drugs inhibit cell wall synthesis, examined time-kill data and binding studies, and provided a scientific basis for the observed synergy in cell-based assays.

Inhibiting Mycobacterium abscessus Cell Wall Synthesis: Using a Novel Diazabicyclooctane ß-Lactamase Inhibitor To Augment ß-Lactam Action.

Mycobacterium abscessus (Mab) infections are a growing menace to the health of many patients, especially those suffering from structural lung disease and cystic fibrosis. With multidrug resistance a common feature and a growing understanding of peptidoglycan synthesis in Mab, it is advantageous to identify potent ß-lactam and ß-lactamase inhibitor combinations that can effectively disrupt cell wall synthesis. To improve existing therapeutic regimens to address serious Mab infections, we evaluated the ability of durlobactam (DUR), a novel diazobicyclooctane ß-lactamase inhibitor to restore in vitro susceptibilities in combination with ß-lactams and provide a biochemical rationale for the activity of this compound. In cell-based assays, susceptibility of Mab subsp. abscessus isolates to amoxicillin (AMOX), imipenem (IMI), and cefuroxime (CXM) was significantly enhanced with the addition of DUR. The triple drug combinations of CXM-DUR-AMOX and IMI-DUR-AMOX were most potent, with MIC ranges of ≤0.06 to 1 µg/mL and an MIC50/MIC90 of ≤0.06/0.25 µg/mL, respectively. We propose a model by which this enhancement may occur, DUR potently inhibited the ß-lactamase BlaMab with a relative Michaelis constant (Ki app) of 4 × 10-3 ± 0.8 × 10-3 µM and acylation rate (k2/K) of 1 × 107 M-1 s-1. Timed mass spectrometry captured stable formation of carbamoyl-enzyme complexes between DUR and LdtMab2-4 and Mab d,d-carboxypeptidase, potentially contributing to the intrinsic activity of DUR. Molecular modeling showed unique and favorable interactions of DUR as a BlaMab inhibitor. Similarly, modeling showed how DUR might form stable Michaelis-Menten complexes with LdtMab2-4 and Mab d,d-carboxypeptidase. The ability of DUR combined with amoxicillin or cefuroxime and imipenem to inactivate multiple targets such as d,d-carboxypeptidase and LdtMab2,4 supports new therapeutic approaches using ß-lactams in eradicating Mab. IMPORTANCE Durlobactam (DUR) is a potent inhibitor of BlaMab and provides protection of amoxicillin and imipenem against hydrolysis. DUR has intrinsic activity and forms stable acyl-enzyme complexes with LdtMab2 and LdtMab4. The ability of DUR to protect amoxicillin and imipenem against BlaMab and its intrinsic activity along with the dual ß-lactam target redundancy can explain the rationale behind the potent activity of this combination.

Cyclic di-AMP Oversight of Counter-Ion Osmolyte Pools Impacts Intrinsic Cefuroxime Resistance in Lactococcus lactis.

The broadly conserved cyclic di-AMP (c-di-AMP) is a conditionally essential bacterial second messenger. The pool of c-di-AMP is fine-tuned through diadenylate cyclase and phosphodiesterase activities, and direct binding of c-di-AMP to proteins and riboswitches allows the regulation of a broad spectrum of cellular processes. c-di-AMP has a significant impact on intrinsic ß-lactam antibiotic resistance in Gram-positive bacteria; however, the reason for this is currently unclear. In this work, genetic studies revealed that suppressor mutations that decrease the activity of the potassium (K+) importer KupB or the glutamine importer GlnPQ restore cefuroxime (CEF) resistance in diadenylate cyclase (cdaA) mutants of Lactococcus lactis Metabolite analyses showed that glutamine is imported by GlnPQ and then rapidly converted to glutamate, and GlnPQ mutations or c-di-AMP negatively affects the pools of the most abundant free amino acids (glutamate and aspartate) during growth. In a high-c-di-AMP mutant, GlnPQ activity could be increased by raising the internal K+ level through the overexpression of a c-di-AMP-insensitive KupB variant. These results demonstrate that c-di-AMP reduces GlnPQ activity and, therefore, the level of the major free anions in L. lactis through its inhibition of K+ import. Excessive ion accumulation in cdaA mutants results in greater spontaneous cell lysis under hypotonic conditions, while CEF-resistant suppressors exhibit reduced cell lysis and lower osmoresistance. This work demonstrates that the overaccumulation of major counter-ion osmolyte pools in c-di-AMP-defective mutants of L. lactis causes cefuroxime sensitivity.IMPORTANCE The bacterial second messenger cyclic di-AMP (c-di-AMP) is a global regulator of potassium homeostasis and compatible solute uptake in many Gram-positive bacteria, making it essential for osmoregulation. The role that c-di-AMP plays in ß-lactam resistance, however, is unclear despite being first identified a decade ago. Here, we demonstrate that the overaccumulation of potassium or free amino acids leads to cefuroxime sensitivity in Lactococcus lactis mutants partially defective in c-di-AMP synthesis. It was shown that c-di-AMP negatively affects the levels of the most abundant free amino acids (glutamate and aspartate) in L. lactis Regulation of these major free anions was found to occur via the glutamine transporter GlnPQ, whose activity increased in response to intracellular potassium levels, which are under c-di-AMP control. Evidence is also presented showing that they are major osmolytes that enhance osmoresistance and cell lysis. The regulatory reach of c-di-AMP can be extended to include the main free anions in bacteria.

Mode of bacterial killing affects the inflammatory response and associated organ dysfunctions in a porcine E. coli intensive care sepsis model.

BACKGROUND: Sepsis is often treated with penicillin-binding protein 3 (PBP-3) acting ß-lactam antibiotics, such as piperacillin-tazobactam, cefotaxime, and meropenem. They cause considerable bacterial structural changes and have in vitro been associated with an increased inflammatory response. In a clinically relevant large animal sepsis model, our primary aim was to investigate whether bacteria killed by a PBP-3-active antibiotic has a greater effect on the early inflammatory response and organ dysfunction compared with corresponding amounts of live or heat-killed bacteria. A secondary aim was to determine whether the addition of an aminoglycoside could mitigate the cefuroxime-induced response. METHOD: Killed or live Escherichia coli were administrated as a 3-h infusion to 16 healthy pigs in a prospective, randomized controlled interventional experimental study. Cefuroxime was chosen as the PBP-3-active antibiotic and tobramycin represented the aminoglycosides. The animals were randomized to receive (I) bacteria killed by cefuroxime, (II) live bacteria, (III) bacteria killed by heat, or (IV) bacteria killed by the combination of cefuroxime and tobramycin. Plasma endotoxin, tumor necrosis factor alpha, interleukin-6, interleukin-10, leukocytes, and organ function were recorded at the start of the experiment and then hourly for 6 h. RESULTS: Differences in dynamics of concentration over time between the four treatment groups were found for the three cytokines (p < 0.001). Animals receiving cefuroxime-killed bacteria demonstrated higher responses than those receiving live (p < 0.05) or heat-killed bacteria (p < 0.01). The addition of tobramycin reduced the cefuroxime-induced responses (p < 0.001). The cytokine responses were associated with leucocyte activation that was further associated with pulmonary dysfunction and increases in lactate (p < 0.01). CONCLUSIONS: In comparison with live or heat-killed bacteria, bacteria killed by a PBP-3-active antibiotic induced an increased inflammatory response that appears to be associated with deteriorated organ and cellular function. The addition of an aminoglycoside to the PBP-3-active antibiotic reduced that response.

Antibacterial effect of fosfomycin tromethamine on the bacteria inside urinary infection stones.

OBJECTIVE: This study sought to evaluate the antibacterial effect of fosfomycin tromethamine (FT) on the bacteria inside urinary infection stones. METHODS: The internal structures of urinary stones were observed via scanning electron microscopy to verify the presence of internal bacteria. We randomly assigned equal numbers of patients with kidney stones who met the inclusion criteria into two groups in a prospective study and treated them with different perioperative antibiotics. One group (experimental group) was treated with FT, and the other (control group) was treated with cefuroxime sodium. All stone specimens were collected via percutaneous nephrolithotomy (PCNL). The primary infection stones were screened via a stone component analysis, 30 cases in the experimental group and 31 cases in the control group. High-performance liquid chromatography (HPLC)-mass spectrometry was used to measure the drug concentration inside the stones, the bacterial count was calculated via stone culture, and the clinical infection index were monitored for between-group comparisons. RESULTS: Compared with the control group, the experimental group had a higher internal drug concentration, a higher drug sensitivity against various pathogenic bacteria, a lower bacterial colony count in the stone culture, and a lower incidence of postoperative clinical infection. CONCLUSIONS: FT is more effective than cefuroxime, which is commonly used during the perioperative period of urinary stones, and exerts a high antibacterial effect on these internal bacteria, and effectively reduces the probability of infection and sepsis after urinary stone surgery. FT can be used as an antibiotic during the perioperative period of urinary stones.

Tryptoline-based benzothiazoles re-sensitize MRSA to ß-lactam antibiotics.

Resistance-modifying agents (RMAs) offer a promising solution to combat bacterial antibiotic resistance. Here we report the discovery and structure-activity relationships of a new class of RMAs with a novel tryptoline-based benzothiazole scaffold. Our most potent compound in this series (4ad) re-sensitizes multiple MRSA strains to cephalosporins at low concentrations (2 µg/mL) and has low mammalian cytotoxicity with a half growth inhibitory concentration (GI50) > 100 µg/mL in human cervical carcinoma (HeLa) cells. In addition, the same core scaffold with different substitutions also gives good antibacterial activity against MRSA.

Investigating the effect of intracameral cefuroxime on oxidative stress and apoptosis in the rat cornea / Investigando o efeito de cefuroxima intracameral sobre o estresse oxidativo e a apoptose na córnea de ratos

ABSTRACT PURPOSE: We examined the effect of intracameral administration of cefuroxime on oxidative stress and endothelial apoptosis in rat corneal tissue. METHODS: In total, 30 rats were divided into 3 groups of 10 rats each (intracameral administration of cefuroxime 0.1 mg/0.01 mL (cefuroxime group); intracameral administration of balanced salt solution 0.01 mL (control group); or absence of intracameral injection (sham group). Corneal endothelial apoptosis was assessed by immunohistochemical analysis using caspase-3 and caspase-8. Total oxidant status, total antioxidant status, oxidative stress index, and paraoxonase and arylesterase levels were examined in corneal endothelial tissue and serum. RESULTS: Paraoxonase levels in the serum were significantly different between the sham and cefuroxime groups (p=0.027). A significant difference was also observed in total oxidant status levels between the cefuroxime and balanced salt solution groups (p=0.023). In addition, there were significant differences in total antioxidant status levels in corneal tissue between the cefuroxime and sham groups (p<0.001) and between the cefuroxime and balanced salt solution groups (p<0.001). Furthermore, significant differences were also observed in oxidative stress index levels between the cefuroxime and balanced salt solution groups (p=0.001) and between the cefuroxime and sham groups (p=0.026). According to the immunohistochemical staining results, a significant association with caspase-3 activity existed between the cefuroxime and balanced salt solution groups (p=0.007), while no significant difference was found with caspase-8 activity (p=0.541). Caspase-3 activity exhibited a significant relationship between the sham and balanced salt solution groups (p=0.018), but no relationship was found with caspase-8 activity (p=0.623). CONCLUSION: Immunohistochemical examination revealed that intracameral cefuroxime increased apoptosis when compared to the sham and balanced salt solution groups. Moreover, intracameral cefuroxime increased oxidative stress in the cornea and simultaneously induced apoptosis.

RESUMO OBJETIVO: Examinamos o efeito da administração intracameral da cefuroxima sobre o estresse oxidativo e a apoptose endotelial no tecido corneano de ratos. MÉTODOS: No total, 30 ratos foram divididos em 3 grupos de 10 ratos cada (administração intracameral de cefuroxima 0,1 mg/0,01 mL (grupo cefuroxima), administração intracameral de solução salina balanceada 0,01 mL (grupo controle) ou ausência de injeção intracameral (grupo sham)). A apoptose endotelial da córnea foi avaliada por análise imuno-histoquimica usando caspase-3 e -8. O status oxidante total, o status antioxidante total, o índice de estresse oxidativo e os níveis de a paraoxonase e arilesterase foram investigados no tecido endotelial da córnea e no soro. RESULTADOS: Os níveis de paraoxonase no soro foram significativamente diferentes entre os grupos sham e cefuroxima (p=0,027). Foi também observada uma diferença significativa nos níveis de estado oxidante total entre os grupos cefuroxima e solução salina balanceada (p=0,023). Além disso, houve diferenças significativas nos níveis de status antioxidante total no tecido da córnea entre os grupos cefuroxima e sham (p<0,001) e entre os grupos cefuroxima e solução salina balanceada (p<0,001). Diferenças significativas também foram observadas nos níveis do índice de estresse oxidativo entre os grupos cefuroxima e solução salina balanceada (p=0,001) e entre os grupos cefuroxima e sham (p=0,026). De acordo com os resultados de coloração imuno-histoquimica, houve associação significativa com a atividade da caspase-3 entre os grupos cefuroxima e solução salina balanceada (p=0,007), enquanto não houve diferença significativa com a atividade da caspase-8 (p=0,541). A atividade da caspase-3 exibiu uma relação significativa entre os grupos sham e solução salina balanceada (p=0,018), mas nenhuma relação foi encontrada com a atividade da caspase-8 (p=0,623). CONCLUSÃO: O exame imuno-histoquímico revelou que a cefuroxima intracameral aumentou a apoptose quando comparada com os grupos sham e solução salina balanceada. Além disso, a cefuroxima intracameral aumentou o estresse oxidativo na córnea e induziu simultaneamente a apoptose.

In vivo biochemical evaluations of some ß-lactam group antibiotics on glutathione reductase and glutathione S- transferase enzyme activities.

OBJECTIVES: The aim of this study was to investigate whether some of the cephalosporin group antibiotics have inhibition effects on GR and GST enzymes with important functions in the metabolic pathway. METHODS: In this study, some selected cephalosporin group antibiotics on GST and GR enzyme was carried out using 96 rats. 16 groups (16 × 6) were created from these rats, divided to another 4 groups (4 × 24). The resulting groups were named as sham groups, cefazolin groups, cefuroxime groups and cefoperazone groups, respectively. The antibiotics used were injected to cefazolin, cefuroxime and cefoperazone groups. The inhibition effects of the antibiotics were measured in the different time intervals (1st, 3th, 5th, 7th). The statistical investigation of the results was performed using the SPSS software program. RESULTS: Results revealed the complex effects of the tested substances on GR and GST activity at different time intervals and in different tissues (p < 0.05). This indicated that the tested substances could be exposed to different interactions in vivo. CONCLUSION: The tested antibiotics showed some significant inhibition effects on the GST and GR enzyme activity in some tissues of brain, eye and muscle. The interaction of enzyme - the drug is a key factor to highlight the toxicological mechanism. For this reason, the results obtained from in vivo experiments are crucial to explane the physiological properties of the enzymes.

Diatom shell incorporated PHBV/PCL-pullulan co-electrospun scaffold for bone tissue engineering.

Tissue engineering can benefit from wide variety of materials produced by microorganisms. Natural origin materials often possess good biocompatibility, biodegradability with sustainable production by microorganisms. A phytoplankton, diatom, produces an amorphous silica shell that can be obtained by a cost efficient production process. Diatom shells (DS) are promising for bone tissue engineering since silicon enhances bone regeneration. Biocompatible and biodegradable biopolymers with microorganism origin can be combined with DS to produce tissue engineering constructs. In this study, a novel multifunctional 3D fibrous scaffold for bone tissue engineering was produced by co-electrospinning system; antibiotic loaded poly(hydroxybutyrate-co-hydroxyvalerate)/poly(ε-caprolactone) (PHBV/PCL) fibers and DS incorporated pullulan (PUL) fibers. Controlled release of cefuroxime axetil (CA) from DS and scaffolds were investigated upon loading CA into DS or PHBV/PCL fibers. Purified DS were characterized with ESCA, SEM, and EDX analyses while scaffolds were evaluated in terms of morphology, porosity, degradation, calcium deposition, water retention and mechanical properties. In vitro studies showed that scaffolds bearing DS have improved human osteosarcoma (Saos-2) cell viability. Developed co-electrospun scaffold showed higher osteocompatibility with better cell spreading and cell distribution. Results showed that DS loaded, co-electrospun scaffold having both hydrophobic and hydrophilic characteristics can be a promising biomaterial for bone tissue engineering.

Bacteriology and cefuroxime resistance in endophthalmitis following cataract surgery before and after the introduction of prophylactic intracameral cefuroxime: a retrospective single-centre study.

BACKGROUND: Intracameral cefuroxime as prophylaxis against postoperative endophthalmitis (POE) following cataract surgery was introduced in 1996 at St Erik Eye Hospital. Soon after the introduction of intracameral cefuroxime, the rate of POE fell dramatically and a shift in the aetiology was noticed. AIM: To analyse bacteriology and susceptibility to cefuroxime before and after the introduction of intracameral cefuroxime. METHODS: All culture-proven cases of endophthalmitis at St Erik Eye Hospital after cataract surgery performed over a 20-year period were included in a retrospective observational study. FINDINGS: Sixty-two cases of endophthalmitis occurred in 34,390 (0.18%) cataract surgeries before the introduction of intracameral cefuroxime (Period 1), while 33 cases occurred in 75,144 (0.044%) operations after the introduction of intracameral cefuroxime (Period 2), showing a significant difference between the periods (P < 0.001). The incidence of coagulase-negative staphylococci (1/1400 vs 1/15,000; P < 0.001), Staphylococcus aureus (1/2000 vs 1/30,000; P < 0.001), streptococci other than enterococci (1/2500 vs 1/25,000; P < 0.001) and Propionibacterium acnes (1/16,000 vs 0/75,000; P = 0.04) fell sharply in Period 2. Cefuroxime-sensitive strains became less frequent in Period 2 (P < 0.001). Enterococci became the predominant species, albeit not significantly (P = 0.13), whereas the rate of cefuroxime-resistant strains almost reached significance (P = 0.05) in Period 2. CONCLUSIONS: Intracameral cefuroxime leads to a reduction of the rate of endophthalmitis after cataract surgery, and brings about a shift in pathogens from cefuroxime-sensitive to cefuroxime-resistant organisms.

Colo-Pro: a pilot randomised controlled trial to compare standard bolus-dosed cefuroxime prophylaxis to bolus-continuous infusion-dosed cefuroxime prophylaxis for the prevention of infections after colorectal surgery.

Standard bolus-dosed antibiotic prophylaxis may not inhibit growth of antibiotic resistant colonic bacteria, a cause of SSIs after colorectal surgery. An alternative strategy is continuous administration of antibiotic throughout surgery, maintaining concentrations of antibiotics that inhibit growth of resistant bacteria. This study is a pilot comparing bolus-continuous infusion with bolus-dosed cefuroxime prophylaxis in colorectal surgery. This is a pilot randomised controlled trial in which participants received cefuroxime bolus-infusion (intervention arm) targeting free serum cefuroxime concentrations of 64 mg/L, or 1.5 g cefuroxime as a bolus dose four-hourly (standard arm). Patients in both arms received metronidazole (500 mg intravenously). Eligible participants were adults undergoing colorectal surgery expected to last for over 2 h. Results were analysed on an intention-to-treat basis. The study was successfully piloted, with 46% (90/196) of eligible patients recruited and 89% (80/90) of participants completing all components of the protocol. A trialled bolus-continuous dosing regimen was successful in maintaining free serum cefuroxime concentrations of 64 mg/L. No serious adverse reactions were identified. Rates of SSIs (superficial and deep SSIs) were lower in the intervention arm than the standard treatment arm (24% (10/42) vs. 30% (13/43)), as were infection within 30 days of operation (41% (17/43) vs 51% (22/43)) and urinary tract infections (2% (1/42) vs. 9% (4/43)). These infection rates can be used to power future clinical trials. This study demonstrates the feasibility of cefuroxime bolus-continuous infusion of antibiotic prophylaxis trials, and provides safety data for infusions targeting free serum cefuroxime concentrations of 64 mg/L. Trial registration: NCT02445859 .

Cefuroxime conjugated chitosan hydrogel for treatment of wound infections.

Hydrogels are excellent drug delivery systems for the treatment of chronic wound infections. However, the problem of high burst release still remains a challenge that needs to be tackled. In terms of antibiotic release from the hydrogels, as the drug payload depletes it could act as a substrate for bacterial seeding which can create a life-threatening condition. Therefore, to provide the sustained effect of an antibiotic at the localized site via hydrogel matrix, we prepared a chitosan (CS) hydrogel system in which cefuroxime (CEF) is covalently conjugated with chitosan polymer via an ester linkage. To prepare the cefuroxime conjugated chitosan hydrogel, the formulations were optimized using different concentrations of cefuroxime, 0% (CS/CEF_0), 5% (CS/CEF_5), 10% (CS/CEF_10) and 20% (CS/CEF_20) w/w of chitosan. Fourier Transform Infra-red Spectroscopy (FTIR) confirmed the conjugation of cefuroxime and chitosan. The drug release studies showed that the release of cefuroxime was higher in the phosphate buffer (pH 7.4) with esterase enzyme and alkaline medium (pH 10) compared to phosphate buffer (pH 7.4) alone. Hemolysis assay was performed to demonstrate the hemocompatibility of the prepared hydrogel samples. The cell viability study using the L929 fibroblast and MG63 osteosarcoma cell lines revealed that synthesized hydrogel is biocompatible. Furthermore, a potent antibacterial activity for the extended time period proved the biological efficacy of a hydrolyzed cefuroxime. Thus, CS/CEF_5, CS/CEF_10, and CS/CEF_20 hydrogels have a promising future in the treatment of chronic wound infections.

Combination Effect of Cefuroxime and Levofloxacin Against Bacteria Isolated from the Healthy Conjunctival Sac and Endophthalmitis Cases Using a Fractional Inhibitory Concentration Index.

PURPOSE: Intracameral cefuroxime (CXM) and antibiotic eye drops such as fluoroquinolone are widely used for preventing endophthalmitis after cataract surgery. However, few reports are available regarding their interactions. This study was conducted to examine the in vitro interaction of CXM and levofloxacin (LVFX) against bacterial isolates from the healthy conjunctival sac before cataract surgery and from endophthalmitis cases. METHODS: The activity of each drug was determined using a broth dilution method. Checkerboard synergy testing was performed for 43 isolates from the healthy conjunctival sac before cataract surgery and 15 isolates from endophthalmitis cases, respectively. Antimicrobial combinations were classified as synergistic, additive, indifferent, or antagonistic based on their fractional inhibitory concentration (FIC). RESULTS: Minimum inhibitory concentrations of CXM and LVFX against endophthalmitis isolates were compared against conjunctival sac isolates. The average FIC indices of combined CXM and LVFX used in endophthalmitis isolates were significantly lower than those in conjunctival sac isolates (P < 0.001). The synergistic activities of CXM and LVFX combinations were observed in 50% of endophthalmitis isolates and no conjunctival sac isolates. No consistent additive or synergistic effect was observed in Enterococcus faecalis isolates from endophthalmitis cases. CONCLUSIONS: CXM and LVFX resistance was frequently identified in the endophthalmitis isolates. However, CXM and LVFX combination showed a synergistic effect against endophthalmitis isolates and increased the antibiotic activity of each drug, suggesting that the combination may improve effects of both antibiotics and combat drug-resistant bacteria that cause endophthalmitis.

Does cefuroxime alter fracture healing in vivo? A micro-computertomographic, biomechanical, and histomorphometric evaluation using a rat fracture model.

Cefuroxime is widely used for antibiotic prophylaxis in orthopedic surgery. However, a recent study indicated a dose-dependent reduction in osteoblast function in vitro. Nevertheless, cell culture might not sufficiently imitate the complex process of bone remodeling. As data concerning possible in vivo interactions of cefuroxime on fracture healing are completely missing, we investigated the following hypothesis: Does Cefuroxime impair bone healing in vivo? Therefore, 34 male Wistar rats were randomised to cefuroxime-treated or control groups, a Kirschner wire was inserted into right femora and closed transverse fractures were produced. Twenty-one days later, the structural properties of the fracture callus in the early fracture healing phase were evaluated via a combination of micro-CT (µCT), biomechanics and histology. µCT demonstrated similar values in the cefuroxime and control group (e.g., callus volume: 67.19 ± 14.90 mm3 vs. 55.35 ± 6.74 mm3 , p = 0.12; density: 635.48 ± 14.81 mg HA/cm3 vs. 647.87 ± 13.01 mg HA/cm3 , p = 0.16). Biomechanically, similar values were again determined between the groups, in terms of both maximum load (77.65 ± 41.82 vs. 78.54 ± 20.52, p = 0.95) and stiffness (122.44 ± 81.16 vs. 123.74 ± 60.08, p = 0.97). Histological findings were consistent with the radiographic results. Thus, no relevant differences between the cefuroxime and control groups could be found and the reported negative effects on osteoblasts in vitro were not confirmed in vivo by using standard concentrations of cefuroxime. In conclusion, cefuroxime can reasonably be recommended in a clinical setting as an antibiotic therapy when fracture healing is involved. However, supraphysiological doses were not evaluated, which may be present when cefuroxime is used as an additive to bone cement and released over time. Therefore, future studies should evaluate the in vivo effects of prolonged high cefuroxime doses on implant incorporation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2282-2291, 2017.

Safety Profile of Stromal Hydration of Clear Corneal Incisions with Cefuroxime in the Mouse Model.

PURPOSE: The use of sutureless clear corneal incisions (CCIs) for phacoemulsification is an established surgical technique, but the dynamic morphology of the wound and poor construction can lead to an increased risk of postoperative endophthalmitis. Stromal hydration with balanced salt solution (BSS) can improve the self-sealing status. Intracameral cefuroxime has reduced endophthalmitis rates. This study investigates the safety profile of stromal hydration with cefuroxime, as sequestering antibiotic at the wound may potentially provide added protection against infection. METHODS: MF-1 mice underwent bilateral CCI, followed by stromal hydration with 5 µL of 10 mg/mL cefuroxime, cefuroxime-texas red conjugate (for detection using confocal microscopy), or BSS. Corneas were harvested from 1 h to 12 weeks postoperatively; gross morphology, histology, and apoptotic cell death levels were investigated to determine the safety profile. Bactericidal activity of cefuroxime was assayed using homogenized whole cornea following stromal hydration at 1 h, 24 h, and day 7 against gram-negative Escherichia coli. RESULTS: Cefuroxime stromal hydration did not alter corneal morphology, with no evidence of corneal scarring or vascularization. Corneal histology and levels of apoptosis were minimal and comparable to the BSS groups up to 12 weeks. Confocal microscopy detected cefuroxime-texas red up to 1 week surrounding the corneal wound. Whole corneal tissue homogenates displayed bactericidal activity up to 24 h postoperatively. CONCLUSIONS: Stromal hydration of CCI with cefuroxime is safe in mouse corneas. A reservoir of antibiotic at the wound can potentially act as a barrier of defense against infection following cataract and associated ocular surgery.

Novel water soluble neutral vanadium(IV)-antibiotic complex: Antioxidant, immunomodulatory and molecular docking studies.

A novel water soluble five coordinate oxovanadium(IV) complex, [VO(C16H15N4O8S)HSO4] incorporating cefuroxime, a cephalosporin group of antibiotic have been prepared from an interaction of vanadyl sulfate and cefuroxime in aqueous solution. The compound was characterized by Fourier transform infrared spectroscopy (FTIR), CHN microanalyses, ultraviolet-visible spectroscopy (UV-Vis), fast atom bombardment (FAB) mass spectrometry and thermogravimetric analysis (TGA). Density Functional Theory (DFT) computation using Gaussian 09 program at B3LYP level revealed a distorted square pyramidal energy optimized geometry for the vanadyl(IV) complex. The molecular docking studies show that the interaction between the vanadium complex and protein receptor, clathrin is dominated by hydrophobic forces. The experimental (1)H nuclear magnetic resonance (NMR) features of the analogous Zn(II) complex matched well with the theoretically computed values further affirming the distorted square pyramidal geometry for the vanadyl(IV) complex. Cyclic voltammetry revealed a metal centered single-electron oxidation-reduction response for VO(IV)/VO(V) couple. The antioxidant activity of the vanadium(IV)-complex vis-à-vis the antibiotic has been assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The vanadium complex showed comparatively better radical scavenging ability compared to the antibiotic cefuroxime. The antimicrobial activity of the compound has been assayed for five different microbial strains using minimum inhibitory concentration (MIC) method. Immunomodulatory studies carried out using phagocytosis index, myeloperoxidase release and cytokine assay indicated the vanadium(IV)-complex to be immunosuppressant. The cytotoxicity of the compound was evaluated by MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) reduction assay.

Iontophoresis of amoxicillin and cefuroxime: rapid therapeutic concentrations in skin.

CONTEXT: Amoxicillin (AMX) and cefuroxime (CFX) are antibiotics used often to treat skin bacterial infections. Typically, high oral doses are required to achieve minimum inhibitory concentration (MIC) at the site of infection that may affect only a very small area of skin. OBJECTIVES: To lower side effects and increase therapeutic effectiveness, the percutaneous absorption and retention of AMX and CFX administered by iontophoresis was investigated in a rabbit model by measuring dermis concentrations via microdialysis. METHODS: Iontophoresis was performed using a stainless steel electrode and a non-woven polypropylene pad. The cartridge pad was soaked with a solution of AMX in glycerin or of CFX in glycerin/water (60:40). Constant current density of 0, 100, 200 or 300 µA/cm(2) was applied for 60 min. RESULTS: For AMX, therapeutically effective skin concentrations were detected immediately after the application of electrical current for any of the current density tested and remained above it for at least 2 h from the end of iontophoresis. For CFX, skin concentrations rose above MIC only at the higher current densities and fell below the MIC by the end of the experiment. CONCLUSION: Iontophoresis is a promising method to obtain a fast and sustained concentration of AMX and CFX in skin.

A newly designed total implantable venous access device in rats for research with high efficiency and low cost.

BACKGROUND: In this study, we introduced a newly designed totally implantable device for long-term vascular access in rats and compared its efficacy, related complications, and cost-effectiveness with conventional exteriorized jugular vein catheters. METHODS: Forty adult male Sprague-Dawley rats, weighing 250-300 g, were equally divided into two groups (I and II) and all underwent jugular vein catheterization surgery. The totally implanted device was used in group I and conventional exteriorized catheters were used in group II. The functionality of each catheter was checked every 3 d and evaluation included vascular accessibility, patency, and infection. The weight of the animal and microbial culture from the wound and tube were also monitored. We analyzed the cause of vascular access failure and complications, both mechanical and infectious, and compared related variables. RESULTS: The proportions of 9-d patency and 30-d patency in group I were 90% (18/20) and 75% (15/20), respectively, and in group II 80% (16/20) and 35% (7/20), respectively. There was a statistically significant difference in 30-d patency. The rats in group II were more liable to involve vascular access failure because of catheter dislodgment and had a higher infection rate (P = 0.001). Daily body weight gain was also greater in group I than in group II (2.46 ± 0.59 g/d versus 1.84 ± 0.96 g/d; P = 0.02). CONCLUSIONS: This newly designed and totally implanted device substantially increases the success rate of long-term venous access compared with conventional methods. It reinforces the merits of the subcutaneous port and a tethered swivel system and overall has better performance and reliability. Furthermore, given its low cost and the high level of effectiveness offered, this technology could be a powerful tool to be used in future translational medicine research, especially in cases of long-term intravascular administration.

[Spectrum and susceptibility of preoperative conjunctival bacteria]. / Espectro y susceptibilidad de las bacterias conjuntivales preoperatorias.

PURPOSE: To describe the conjunctival bacterial spectrum of our patients undergoing intraocular surgery and their antibiotic sensitivity during the study period. METHODS: A retrospective study of preoperative conjunctival culture of patients consecutively scheduled for intraocular surgery from 21 February 2011 to 1 April 2013. Specimens were directly seeded onto blood-agar and MacConkey-agar (aerobiosis incubation, 2 days), and on chocolate-agar (6% CO2 incubation, 7 days). The identified bacteria were divided into 3 groups according to their origin; the bacteria susceptibility tests were performed on those more pathogenic and on some of the less pathogenic when more than 5 colonies were isolated. The sensitivity of the exigent growing bacteria was obtained with disk diffusion technique, and for of the non-exigent bacteria by determining their minimum inhibitory concentration. The Epidat 3.1 program was used for statistical calculations. RESULTS: A total of 13,203 bacteria were identified in 6,051 cultures, with 88.7% being typical colonizers of conjunctiva (group 1), 8.8% typical of airways (group 2), and the remaining 2.5% of undetermined origin (group 3). 530 cultures (8.8%) were sterile. The sensitivity of group 1 was: 99% vancomycin, 95% rifampicin, 87% chloramphenicol, 76% tetracycline. Levels of co-trimoxazole, aminoglycosides, quinolones, ß-lactams and macrolides decreased since 2007. The group 2 was very sensitive to chloramphenicol, cefuroxime, rifampicin, ciprofloxacin and amoxicillin/clavulanate. In group 3, to levofloxacin 93%, ciprofloxacin 89%, tobramycin 76%, but ceftazidime 53% and cefuroxime 29% decreased. CONCLUSIONS: None of the tested antibiotics could eradicate all possible conjunctival bacteria. Bacteria living permanently on the conjunctiva (group 1) have achieved higher resistance than the eventual colonizers.