Kinds Of Antimicrobial Agents Research Articles

Fungal communities in the biofilms colonizing the basalt sculptures of the Leizhou Stone Dogs and assessment of a conservation measure

The Leizhou Peninsula in China is very famous for its unique folk art creation, especially for the stonework, like the basalt sculptures of the Leizhou Stone Dogs, which have a history of more than two thousand years. Since these sculptures are usually exposed outdoors, many of them are suffering from severe damage by lichen and fungi. To protect them from microbial attack, we determined fungal communities in the biofilms colonizing the stone dogs and explored an effective conservation measure. Specifically, the micromorphology analysis of the biofilms on the stone dogs was performed through both on-site and laboratory-based microscopies in order to provide an overview of the fungal community structure. High-throughput sequencing analysis revealed that the predominant fungi in the biofilms belong to the following genera Caloplaca, Chaetomium, Clitopilus, Acanthostigma, Tolypocladium, Aspergillus, and Toxicocladosporium. The energy dispersive X-ray spectrometry (EDS) showed that the basalt is mainly composed of silica (53% by weight), followed by Al2O3 (14.4%), Fe2O3 (10.1%), CaO (8.4%), and MgO (7.4%) that are oxides susceptible to corrosion of biogenic acids. The EDS analysis of the hyphae provided the direct evidence on the leaching of the minerals of the sculptures. To control microbial attack, three kinds of antimicrobial agents were tested for 2 years. As a result, the mixture of biocide and water repellent showed the best effectiveness. Our findings provide an overview of fungi diversity in the biofilms on the stone dogs and help the investigation of fungi-induced biodeterioration and the exploration of specific conservation measure.

Risk Factors for Acute Cholangitis Caused by Enterococcus faecalis and Enterococcus faecium.

Background/AimsAcute cholangitis (AC) is a potentially life-threatening bacterial infection, and timely antimicrobial treatment, faster than that achieved with bacterial cultures, is recommended. Although the current guidelines refer to empirical antimicrobial treatment, various kinds of antimicrobial agents have been cited because of insufficient analyses on the spectrum of pathogens in AC. Enterococcus spp. is one of the most frequently isolated Gram-positive bacteria from the bile of patients with AC, but its risk factors have not been extensively studied. This study aimed to analyze the risk factors of AC caused by Enterococcus faecalis and Enterococcus faecium.MethodsPatients with AC who were hospitalized in a Japanese tertiary center between 2010 and 2015 were retrospectively analyzed. Patients’ first AC episodes in the hospital were evaluated.ResultsA total of 266 patients with AC were identified. E. faecalis and/or E. faecium was isolated in 56 (21%) episodes of AC. Prior endoscopic sphincterotomy (EST), the presence of a biliary stent, prior cholecystectomy, and past intensive care unit admission were more frequently observed in AC patients with E. faecalis and/or E. faecium than in those without such bacteria. Prior EST was identified as an independent risk factor for AC caused by E. faecalis and/or E. faecium in the multivariate analysis.ConclusionsGiven the intrinsic resistance of E. faecalis and E. faecium to antibiotics, clinicians should consider empirical therapy with anti-enterococcal antibiotics for patients with prior EST.

Rifampicin conjugated silver nanoparticles: a new arena for development of antibiofilm potential against methicillin resistant Staphylococcus aureus and Klebsiella pneumoniae.

Background: Infections caused by drug resistant bacteria are a major health concern worldwide and have prompted scientists to carry out efforts to overcome this challenge. Researchers and pharmaceutical companies are trying to develop new kinds of antimicrobial agents by using different physical and chemical methods to overcome these problems.Materials and methods: In the present study, rifampicin conjugated silver (Rif-Ag) nanoparticles have successfully been synthesized using a chemical method. Characterization of the nanoparticles was performed using a UV-Vis spectrophotometer, FTIR, SEM, TEM, and AFM.Results: The AFM, SEM, and TEM results showed that the average particle size of Rif-Ag nanoparticles was about 15–18±4 nm. The FTIR spectra revealed the conjugation of –NH2 and –OH functional moiety with silver nanoparticles surface. Considering the penetrating power of rifampicin, the free drug is compared with synthesized nanoparticle for antimicrobial, biofilm inhibition, and eradication potential. Synthesized nanoparticles were found to be significantly active as compared to drug alone.Conclusion: This study has shown greater biofilm inhibitory and eradicating potential against methicillin resistant Staphylococcus aureus and Klebsiella pneumoniae, as evident by crystal violet, MTT staining, and microscopic analysis. So, it will be further modified, and studies for the mechanism of action are needed.

Characterization of antimicrobial activity of three Lactobacillus plantarum strains isolated from Chinese traditional dairy food.

Many Lactobacillus plantarum strains can secrete some antimicrobial substances and be added to food as antimicrobial agents and preservatives. In this study, three L. plantarum strains (P1, S11, and M7) with strong antimicrobial activity against three pathogenic bacteria were isolated from Xinjiang traditional dairy products. Five common organic acids produced by fermentation of strains play a key role in inhibiting three pathogenic bacteria. At the same pH, the antimicrobial activity of the fermentation broth against Escherichia coli and Salmonella is stronger than that of the organic acid alone. Thus, three kinds of antimicrobial agents (P1‐1, M7‐1, and S11‐1) mixed with five common organic acids were produced. Moreover, the antimicrobial activity against Salmonella ASI.1174 of the antimicrobial agents was about 30% higher than that of the fermentation broth. In addition, organic acid antimicrobial agents combined in different proportions can inhibit different pathogenic bacteria. According to this result, it is a potential approach to develop novel antimicrobial agents used in food preservation by mixing different organic acids.

Analysis of clinical distribution and drug resistance of pseudomonas aeruginosa in the Sixth Hospital of Ningbo

Objective To investigate the drug resistance of pseudomonas aeruginosa changes in the Sixth Hospital of Ningbo, Zhejiang province, in order to provide a basis for clinical rational use of antimicrobial drugs. Methods The clinical distribution and drug resistance to commonly used antimicrobial agents in 1970 strains of pseudomonas aeruginosa from the Sixth Hospital of Ningbo in 2014-2016 were retrospectively analyzed.The data were statistically analyzed using WHONET 5.6 software, excel software, SPSS17.0 software. Results Clinical specimens isolated 15 963 strains of pathogenic bacteria, including 1 970 strains pseudomonas aeruginosa, accounted for 12.34%.The detection rate of multi-drug resistance pseudomonas aeruginosa(MDRPA) reduced year by year, the detection rate in 2014 was 60.95%, which in 2015 was 58.00%, which in 2016 was 45.58%.Pseudomonas aeruginosa was mainly isolated from sputum(67.16%), followed by wound secretion(23.05%). The detection rate of pseudomonas aeruginosa in ICU and geriatric department was higher, accounted for 20.25% and 25.28% respectively.The resistance of pseudomonas aeruginosa to many kinds of antimicrobial agents was increased from 2014 to 2016, the resistance rates to cefoperazone/ sulbactam were>30% in 3 years, the resistance rate to imipenem was higher than meropenem.The drug resistance of pseudomonas aeruginosa isolated from sputum in ICU was higher than that in geriatric department(all P<0.05). Conclusion Pseudomonas aeruginosa nosocomial infection in the Sixth Hospital of Ningbo is severe, the infection rate and drug resistance monitoring should be strengthened, in order to reduce the infection rate and drug resistance. Key words: Pseudomonas aeruginosa; Drug resistance, bacterial; Infection; Anti-bacterial agents; Small-area analysis

Distribution and drug resistance analysis of carbapenems-resistant Klebsiella pneumoniae

Objective To investigate the clinical distribution and drug resistance of carbapenems-resistant Klebsiella pneumoniae (CRKP). Methods A total of 134 clinical strains of CRKP were collected from inpatients in our hospital from January 2014 to December 2016. VITEK-2 compact automatic microbiological analyzer was used to identify the bacteria and the supporting gram-negative bacterial drug susceptibility card was used for susceptibility testing. The sensitivity of other clinical commonly used antimicrobial agents was measured by K-B method. And the clinical distribution of CRKP and its resistance to antimicrobial agents were investigated and analyzed. Results The clinical strains of CRKP were isolated mainly from urine (n=70, 52.2%) and sputum (n=38, 28.4%). Klebsiella pneumoniae was identified in samples from the department of neurosurgery, including neurosurgery ICU (47.8%, 64/134), ICU (23.9%, 32/134), department of hepatobiliary surgery (8.2%,11/134) and department of urology (6.0%, 8/134). Among all 22 antimicrobial agents tested, the resistant rates of CRKP to 16 antimicrobial agents were >90%, especially for ampicillin it was 100%, and those to 19 antibiotics were >80%, only for tigecycline it was 23.1%. There were 16 strains of CRKP with positive extended spectrum β-lactamases (ESBLs) (11.9%). All the CRKP strains were resistant to more than three kinds of antimicrobial agents, except one strain that was resistant to two kinds. Conclusion There is a wide range of clinical distribution of CRKP, which is resistant to most of antimicrobial agents, while tigecycline still has a strong antibacterial activity to CRKP. Key words: Klebsiella pneumoniae; Carbapenems; Drug resistance

Molecular interaction of triclosan with superoxide dismutase (SOD) reveals a potentially toxic mechanism of the antimicrobial agent

In this article, the interaction mechanism between the superoxide dismutase (SOD) and the triclosan (TCS), a kind of antimicrobial agent which is of widely application with potential effects both on environment and human health, was explored through a series of spectroscopic methods, animal experiment and the molecular docking simulation. The negative free energy change ∆G, enthalpy change (∆H = 162.21 kJmol−1) and entropy change (∆S = 615 Jmol−1K−1) demonstrated that TCS could combine with SOD spontaneously through hydrophobic interaction to form a complex. The binding constants of Ka293 and Ka313 were 1.706 × 103 and 1.2 × 105 Lmol−1, respectively. Furthermore, the interaction could also influence the skeleton structure and secondary contents of SOD. The molecular docking analysis revealed the TCS located between two subunits of SOD, and there was a hydrogen bond between TCS and the residue Asn51 of SOD, which influenced the structure of protein and resulted in a decrease of enzyme activity. This work could help understand the interaction mechanism between SOD and TCS. Moreover, it could also be used to consult for toxicity assessment of TCS at molecular level.

A nano-silver composite based on the ion-exchange response for the intelligent antibacterial applications

As a kind of antimicrobial agent, nano-silver composites have attracted a great deal of interest in biomedical applications. However, the typical loadings of silver nanoparticles (AgNPs) in such composites could result in dose-related cytotoxicity. In this study, a nano-silver composite leading to antimicrobial activity without cytotoxicity was fabricated by loading AgNPs into a dried alginate hydrogel. The biological performance of this composite mainly depended on the release of AgNPs, which needed to be triggered by the ion-exchange response and was further influenced by the loadings of AgNPs in the composite. The antimicrobial activity against E. coli and S. aureus demonstrated that the released silver no less than 678ppb in the medium caused a reduction of 7log10CFU/mL (100%) bacteria. Significantly, the dose (~1.10×103ppb) of released silver was not toxic and allowed attachment, and growth of MC3T3-E1 pre-osteoblast cells. These results supported that the composite was compatible with in vitro mammalian cells yet exhibited antimicrobial activity by carefully designing the loadings of AgNPs within the alginate. Thus, it indicated that the performance of this composite might permit management of bacterial infection in wound beds without impairment of wound healing.

The Dynamic Observation of Plasma Concentration of Antimicrobial Agents During Balanced Ultrafiltration In Vitro

Routine perioperative intravenous antimicrobial agents are administered as surgical prophylaxis. However, whether balanced ultrafiltration during extracorporeal circulation has substantial effect on the concentration of antimicrobial agents remains unclear. The concentrations of antimicrobial agents in plasma and ultrafiltrate samples were measured in this pseudo-extracorporeal circulation model. Extracorporeal circulation consisted of cardiotomy reservoir, membrane oxygenator, and pediatric arterial line filter. A hemoconcentrator was placed between the arterial purge line and oxygenator venous reservoir. Fresh donor human whole blood was added into the circuit and mixed with Ringer's solution to obtain a final hematocrit of 24-28%. Two kinds of antimicrobial agents, cefotiam (320 mg) and cefmetazole (160 mg), were bolus added into the circuit. After 30 min of extracorporeal circulation, zero-balanced ultrafiltration was initiated and arterial line pressure was maintained at approximately 100 mm Hg with a Hoffman clamp. The rate of ultrafiltration (12 mL/min) was controlled by ultrafiltrate outlet pressure. An identical volume of Plasmalyte A was dripped into the circuit to maintain stable hematocrit during 45 min of experiment. Plasma and ultrafiltrate samples were drawn every 5 min, and concentrations of antimicrobial agents (including cefotiam and cefmetazole) were measured with high performance liquid chromatography. Both antimicrobial agents were detected in ultrafiltrate, demonstrating hemoconcentration may remove antimicrobial agents. The concentrations of plasma antimicrobial agents decreased linearly with the increase of ultrafiltrate volume. At end of balanced ultrafiltration, the concentration of plasma cefotiam was 104.96 ± 44.36 mg/L, which is about 44.38% ± 7.42% of the initial concentration (238.95 ± 101.12 mg/L) (P < 0.001); the concentration of plasma cefmetazole decreased linearly to 25.76 ± 14.78 mg/L, which is about 49.69% ± 10.49% of the initial concentration (51.49 ± 28.03 mg/L) (P < 0.001). The total amount of cefotiam in ultrafiltrate is 27.16% ± 12.17% of the total dose administered, whereas cefmetazole in ultrafiltrate is 7.74% ± 4.17%. Balanced ultrafiltration may remove antimicrobial agents from plasma and has a prominent influence on plasma concentration of antimicrobial agent. The strategy of surgical prophylaxis should consider this unique technique during extracorporeal circulation.

Suppressive efficacies of antimicrobial agents against human peripheral-blood mononuclear cells stimulated with T cell mitogen and bacterial superantigen

The immunomodulatory efficacies of 12 antimicrobial agents clinically used were examined against T cell mitogen- or bacterial superantigen-induced proliferation of peripheral-blood mononuclear cells of healthy subjects. Minocycline (CAS 13614-98-7), rifampicin (CAS 13292-46-1), trimethoprim (CAS 738-70-5), and ribavirin (CAS 36791-04-5) significantly inhibited the proliferation of mitogen-stimulated mononuclear cells at 1-100 microg/ ml (p < 0.001), whereas ofloxacin (CAS 82419-36-1) enhanced the proliferation (p < 0.001). Ampicillin (CAS 69- 53-4), lincomycin (CAS 859-18-7), vancomycin (CAS 1404-93-9), sulfamethoxazole (CAS 723-46-6), fosfomycin (CAS 26016-99-9), colistin (CAS 1264-72-8), and polymyxin B (CAS 1405-20-5) showed no significant effect. Minocycline, rifampicin, trimethoprim, and ribavirin also inhibited the proliferation of superantigen-stimulated peripheral-blood mononuclear cells at 1-100 microg/ml (<0.001), whereas ofloxacin stimulated the proliferation (p < 0.001). Rifampicin and minocycline at 10-100 microg/ml significantly inhibited interleukin-2 production from mitogen- or superantigen-stimulated peripheral-blood mononuclear cells (p < 0.025). These results suggest that certain kinds of antimicrobial agents inhibited the proliferation of mitogen- and superantigen-stimulated human peripheral-blood mononuclear cells and suppressed interleukin-2 production from these cells. The ofloxacin effect is immunostimulative, while the drug did not influence the interleukin-2 production.

Antibacterial activity and mechanism of recombinant human - defensin 5 against clinical antibiotic-resistant strains

The increasing clinical bacterial strains resistant to conventional antibiotics have being a great challenge to the public’s health. As a novel kind of antimicrobial agent, defensins are undoubtedly worthy of exploitation for the treatment of antibiotic-resistant bacteria. To evaluate the antibacterial potency of recombinant mature human α-defensin 5 (rmHD5) against clinical pathogenic strains, we examined its antibacterial kinetics and bactericidal efficacy on forty-nine bacterial strains (belonging to eleven species) with different antibiotic-resistant phenotypes, isolated from digestive and urogenital tracts of the inpatient. Meanwhile, the action mechanism of rmHD5 was analyzed by transmission electron microscopy observation and membrane permeability detection. The peptide of rmHD5 was found to possess high potency against all the tested isolates at concentrations of 6 - 12 μg/ml for gram-negative (G-) bacteria and 28 - 32 μg/ml for gram-positive (G+) bacteria. G- bacteria were more susceptible to the peptide than G+ bacteria. Abnormal morphological changes and increased permeabilization of the cytomembrane were observed in both G- bacteria and G+ bacteria treated with rmHD5. The antibacterial activity of rmHD5 may be tightly associated with the biomembrane permeabilization. Recombinant mHD5 is a promising candidate to be developed into therapeutic agents for bacterial infections. Key words: Antibacterial activity, mechanism, antibiotics resistant strain, human alpha defensin 5.

Isolamento e perfil de suscetibilidade de bactérias de pé diabético e úlcera de estase venosa de pacientes admitidos no pronto-socorro do principal hospital universitário do estado de Goiás, Brasil

CONTEXTO: Lesões infectadas de membros inferiores (úlceras diabéticas e úlceras de estase venosa) são causa de grande sofrimento e incapacitação funcional com impacto social, econômico e aumento do risco de complicações severas. OBJETIVO: Caracterizar a microbiota e determinar o perfil de suscetibilidade antimicrobiana das bactérias isoladas de lesões de membros inferiores secundárias a úlcera de estase venosa e pé diabético. MÉTODOS: Foram incluídos no estudo pacientes portadores de lesões de membros inferiores, sendo diabéticos, e pacientes com úlcera de estase venosa, atendidos em um serviço de urgência de um hospital universitário de Goiânia (GO), no período de fevereiro de 2005 a agosto de 2006. A coleta de material foi realizada com swab de algodão para realização de cultura e teste de sensibilidade antimicrobiana, empregando-se técnicas preconizadas. RESULTADOS: Das amostras analisadas, foi detectada a presença de bactérias em 88,46%. Os cocos gram-positivos foram caracterizados como Staphylococcus aureus e Staphylococcus epidermidis. Dentre os bastonetes gram-negativos, detectou-se Pseudomonas aeruginosa,Escherichia coli,Proteus mirabilis e Enterobacter sp. CONCLUSÕES: Os microrganismos isolados das lesões de membros inferiores (pé diabético e úlcera de estase venosa) incluíram bactérias gram-positivas e negativas, sendo Staphylococcus aureus,Pseudomonas aeruginosa e Escherichia coli as mais freqüentes, com elevada resistência a diversos antimicrobianos.

Differences in antimicrobial susceptibility breakpoints for Pseudomonas aeruginosa, isolated from blood cultures, set by the Clinical and Laboratory Standards Institute (CLSI) and the Japanese Society of Chemotherapy

A study was made of the antimicrobial susceptibility to and efficacy of various kinds of antimicrobial agents against 179 strains of Pseudomonas aeruginosa that were isolated from blood cultures at Kansai Medical University Hospital from 1990 through 2004. The annual detection rate was highest in 1994, at 22 strains (6.5%). There were 9 multidrug resistant strains of Pseudomonas aeruginosa (5.0%). Among 14 antimicrobial agents tested for measurements, ciprofloxacin (CPFX) showed the best minimum inhibitory concentration (MIC) 50 value, of 0.25 microg/ml, followed by pazufloxacin (PZFX) and biapenem (BIPM), each at 0.5 microg/ml. When the period of 15 years was divided into three stages, the MIC50 value for each antimicrobial agent was highest in the middle stage (1995 to 1999). Assuming that the percentage of sensitive strains according to the breakpoints set by the Clinical and Laboratory Standards Institute (CLSI) represents the antimicrobial susceptibility rate, amikacin (AMK) showed the best value, of 85.5%. According to the sepsis breakpoint set by the Japanese Society of Chemotherapy (JSC), the efficacy of CPFX showed the highest rate (77.1%) of all the antimicrobial agents tested. Among beta-lactams, BIPM showed the highest efficacy rate, of 67.0%. When the efficacy rates were compared with each other, the difference in efficacy rate between the breakpoint set by the CLSI and the sepsis breakpoint set by the JSC was large for beta-lactams. Comparisons made based on the CLSI criteria showed no difference in cross-resistance rates between CPFX, meropenem (MEPM), and BIPM. However, when comparisons were made using the JSC sepsis breakpoint, MEPM showed a cross-resistance rate of 87.8%, while the rate for BIPM was lower, at 56.1%, with the chi2 test showing a significant difference, at P = 0.0014. In accordance with the pharmacokinetics/pharmacodynamics theory that has been advocated, breakpoints which are more suitable for the clinical setting in Japan should be set so that more effective and more appropriate treatment can be carried out.

Determination of Genomospecies and Characterization of Antimicrobial Resistance of Multi-drug ResistantAcinetobacterspp. Isolates

Acinetobacter species are non-fermentative Gram-negative coccobacilli and they have emerged as important nosocomial pathogens which are associated with the significant multidrug resistance in recent years. Carbapenem-resistant A. baumannii (CRAB) and pandrug-resistant A. baumannii (PDRAB) were reported in 1991 and 1998, respectively. Fiftyeight isolates of Acinetobacter species recovered from a university hospital between August 2004 and March 2005 were investigated for the existence of CRAB, PDRAB, extended-spectrum β-lactamase (ESBL)-producing Acinetobacter and examined for their phenotypic and genotypic characteristics. Genomospecies of Acinetobacter species were determined by amplified rDNA restriction analysis (ARDRA) and antimicrobial susceptibility test was performed with 13 kinds of antimicrobial agents. Metallo-β-lactamase (MBL) producers were screened by modified hodge test and confirmed by imipenem-EDTA disk synergy test. Detection of bla IMP-1 , bla VIM-2 , bla TEM , and bla PER-1 was performed by PCR. Genomic DNAs were analyzed by pulsed-field gel electrophoresis (PFGE). Among 58 isolates of Acinteobacter species, 40 isolates were identified as genospecies 2 (A. baumannii), 9 were 13TU, 5 were A. phenon 6/ct, and 4 were Acinetobacter genospecies 3 by ARDRA. Thirteen isolates were confirmed as MBL-producers and blaIMP-1 and blaVIM-2 were carried by 5 and 8 isolates of them, respectively. MBL-producers were mostly 13TU, A. phenon 6/ct 13TU, and Acinetobacter genospecies 3 and they were susceptible to ciprofloxacin and ampicillin-sulbactam. Bla PER-1 was carried by thirteen isolates and 12 isolates of them were PDRAB showing resistance to all antimicrobial agents tested, including ceftazidime, cefepime, aztreonam, ciprofloxacin, amikacin, gentamicin, ampicillin-sulbactam, and imipenem. In conclusion, most MBL-producers belonged to 13TU, A. phenon 6/ct 13TU, and Acinetobacter genospecies 3 which were susceptible to ciprofloxacin and ampicillin-sulbactam, whereas 12 of 13 PER-1-producers were PDRAB originated from the same clone.

Effects of antimicrobial treatment on fiberglass-acrylic filters.

The aims of the present study were to: (i) analyse a group of antimicrobial agents and to select the most active against test microbial strains; (ii) test the effect of the antimicrobial treatment on air filters in order to reduce microbial colonization. Different kinds of antimicrobial agents were analysed to assess their compatibility with the production process of air filter media. The minimal inhibitory concentration for each antimicrobial agent was determined against a defined list of microbial strains, and an antimicrobial activity assay of filter prototypes was developed to determine the most active agent among the compatible antimicrobials. Then, the most active was chosen and added directly to the filter during the production process. The microbial colonization of treated and untreated filter media was assessed at different working times for different incubation times by stereomicroscope and scanning electron microscope analysis. Some of the antimicrobial agents analysed were more active against microbial test strains and compatible with the production process of the filter media. Filter sections analysis of treated filter media showed a significantly lower microbial colonization than those untreated, a reduction of species both in density and varieties and of the presence of bacteria and fungal hyphae with reproductive structures. This study demonstrated the ability of antimicrobial treatments to inhibit the growth of micro-organisms in filter media and subsequently to increase indoor air quality (IAQ), highlighting the value of adding antimicrobials to filter media. To make a contribution to solving the problem of microbial contamination of air filters, by demonstrating the efficacy of incorporating antimicrobial agents in the filter media to improve IAQ and health.

Preface

A lack of a clear distinction between antimicrobial prophylaxis and therapy still exists in the surgical setting. Major concerns are: 1) Which surgical procedures are eligible for antimicrobial prophylaxis? 2) Which kind of antimicrobial agent should be used for surgical prophylaxis? 3) What is the optimal timing for administering antimicrobial prophylaxis and how long should administration be continued? In this paper we assess the rationales leading to the following answers: 1) Only clean-contaminated and prosthetic clean operations should be eligible for antimicrobial prophylaxis, whereas contaminated or dirty operations should be eligible for "early therapy". 2) First- or second-generation cephalosporins or aminopenicillin/beta-lactamase inhibitors are optimal choices for surgical prophylaxis, depending on location of the surgical wound. 3) The highest licensed dosage of the chosen antimicrobial agent should be administered at induction of anesthesia and redosing should be considered when the intervention lasts more than 2 antibiotic half-lives. This allows maintenance of optimal drug exposure against the potential pathogens in plasma and in the extracellular environment of the potentially contaminated tissues for the entire procedure and for some hours after wound closure. Post-surgical doses are not recommended in most cases whereas ultra-short prophylaxis is preferred.

Release profile of antimicrobial agents from α-tricalcium phosphate cement

A new method for treating carious dentine with α-tricalcium phosphate ( α-TCP) dental cement containing antimicrobial agents has been recently introduced. However, the release behavior of antimicrobial agents from this cement has not yet been clarified. The aim of this study is therefore to examine the release profile of the antimicrobial agents from the α-TCP cement. Three kinds of antimicrobial agents (metronidazole, cefaclor and ciprofloxacin) were added to two commercially available α-TCP cements (new apatite liner type I and type II). The set cements were then immersed in water at 37°C and the released antimicrobial agents and Ca ion were determined at regular intervals for three months. In addition, scanning electron microscopic observations were conducted before and after immersion for three months. The release profile of the cements containing antimicrobial agents varied depending on the types of antimicrobial agents. The incorporation of antimicrobial agents affected the setting reaction of the cements. The release behavior of the drugs also varied depending on the types of the cements. The differences in the release profile between type I and type II cements reflected the structures and compositions of their matrices.