The impact of bacteremia on lipoprotein concentrations and patient's outcome: a retrospective analysis.

Bacteremia is a major clinical challenge requiring early treatment. Metabolic alterations occur during bacteremia, and accordingly plasma concentrations of lipoproteins LDL-C and HDL-C are substantially changed. We questioned whether bacteremia with Gram-negative versus Gram-positive bacteria causes contrasting changes of lipoprotein levels in order to differentiate between the 2-g stain types and if there is a relation with outcome parameters namely ICU-admission, 30-day mortality, duration of hospitalization. This is a retrospective dual-center cross-sectional study, including 258 patients with bacteremia. Plasma lipid levels were analyzed within 48 h to positive blood culture. Upon admission, HDL-C, LDL-C, and total cholesterol (p = 0.99) in plasma did not significantly differ between patients with Gram-negative and Gram-positive bacteremia, while significantly higher triglyceride concentrations were found in Gram-negative bacteremia (p < 0.05). 30-day mortality and ICU admission were associated with lower LDL-C and HDL-C concentrations as compared to survivors and non-ICU patients, and patients with HDL-C < 20 mg dl-1 and LDL-C < 55 mg dl-1 had a relative risk (RR) of 2.85 for ICU therapy requirement and RR = 2 of death within 30 days. Reduced HDL-C and LDL-C concentrations were associated with adverse patient's outcome in bacteremia. Discrimination between Gram-negative and Gram-positive pathogens upon lipoprotein patterns is unlikely.

Lyophilized allogeneic bone tissue as an antibiotic carrier.

The rising number of primary joint replacements worldwide causes an increase of revision surgery of endoprostheses due bacterial infection. Revision surgery using non-cemented implants seems beneficial for the long-term outcome and the use of antibiotic-impregnated bone grafts might control the infection and give a good support for the implant. In this study we evaluated the release of antibiotics from fresh-frozen and lyophilized allogeneic bone grafts. Lyophilized bone chips and fresh frozen bone chips were mixed with gentamicin sulphate, gentamicin palmitate, vancomycin, calcium carbonate/calcium sulphate impregnated with gentamicin sulphate, and calcium carbonate/calcium sulphate bone substitute material impregnated with vancomycin. The efficacy of each preparation was measured by drug release tests and bacterial susceptibility using B. subtilis, S. aureus and methicillin-resistant Staphylococcus aureus. The release of gentamicin from lyophilized bone was similar to the release rate from fresh frozen bone during all the experimental time. That fact might be related to the similar porosity and microstructure of the bone chips. The release of gentamicin from lyophilized and fresh frozen bone was high in the first and second day, decreasing and keeping a low rate until the end of the second week. Depending on the surgical strategy either polymethylmethacrylate or allogeneic bone are able to deliver sufficient concentrations of gentamicin to achieve bacterial inhibition within two weeks after surgery. In case of uncemented revision of joint replacements allogeneic bone is able to deliver therapeutic doses of gentamicin and peak levels immediately after implantation during a fortnight. The use of lyophilized and fresh frozen bone allografts as antibiotic carriers is recommended for prophylaxis of bone infection.

Antibiotic-loaded calcium carbonate/calcium sulfate granules as co-adjuvant for bone grafting.

In this study HERAFILL(®) granules containing gentamicin was evaluated as a bone void filling material once mixed with allograft bone grafts. The efficacy of the bone grafts mixed with HERAFILL(®) was measured by drug release tests and bacterial susceptibility using Bacillus subtilis, Staphylococcus epidermidis and Staphylococcus aureus. The effect of storage at -80 °C on the delivery and efficacy of gentamicin from bone grafts mixed with HERAFILL(®) was also investigated. Higher elution of gentamicin was detected in all stored groups (1 and 6 months) in comparison with non-stored samples. The gentamicin elution released from all groups was efficient on reducing S. aureus and S. epidermidis CFU. The susceptibility tests using S. aureus showed less resistance of the strain after 1 month of the elution storage. That resistance was not observed after 6 months of storage. The capacity of bone grafts to act as gentamicin carriers has been confirmed in this study. The different granules sizes did not interfere in the delivery rate of the antibiotics or in the activity against the bacteria. Storage at -80 °C does not interfere on the antibiotic activity.

Bactericidal activity of N-chlorotaurine against biofilm-forming bacteria grown on metal disks.

Many orthopedic surgeons consider surgical irrigation and debridement with prosthesis retention as a treatment option for postoperative infections. Usually, saline solution with no added antimicrobial agent is used for irrigation. We investigated the activity of N-chlorotaurine (NCT) against various biofilm-forming bacteria in vitro and thereby gained significant information on its usability as a soluble and well-tolerated active chlorine compound in orthopedic surgery. Biofilms of Staphylococcus aureus were grown on metal alloy disks and in polystyrene dishes for 48 h. Subsequently, they were incubated for 15 min to 7 h in buffered solutions containing therapeutically applicable concentrations of NCT (1%, 0.5%, and 0.1%; 5.5 to 55 mM) at 37°C. NCT inactivated the biofilm in a time- and dose-dependent manner. Scanning electron microscopy revealed disturbance of the biofilm architecture by rupture of the extracellular matrix. Assays with reduction of carboxanilide (XTT) showed inhibition of the metabolism of the bacteria in biofilms. Quantitative cultures confirmed killing of S. aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa biofilms on metal alloy disks by NCT. Clinical isolates were slightly more resistant than ATCC type strains, but counts of CFU were reduced at least 10-fold by 1% NCT within 15 min in all cases. NCT showed microbicidal activity against various bacterial strains in biofilms. Whether this can be transferred to the clinical situation should be the aim of future studies.

Influence of poly-N-acetylglucosamine in the extracellular matrix on N-chlorotaurine mediated killing of Staphylococcus epidermidis.

N-chlorotaurine (NCT) has recently been shown to have bactericidal activity against bacterial biofilm on metal discs (Coraca-Huber et al., 2014). In a biofilm, Staphylococcus epidermidis polymerizes poly-N-acetylglucosamine (PNAG) to form an extracellular matrix (ECM). Pseudomonas aeruginosa does not express this PNAG and has been shown to be highly susceptible to NCT. We compared the action of NCT on S. epidermidis 1457, a PNAG positive strain (SE1457) and S. epidermidis 1457- M10 an isogenic PNAG negative mutant (SE1457 M10). NCT-mediated killing was more effective and quicker on the PNAG negative strain SE1457 M10. Bacteria hidden in biofilms for prolonged periods of time were generally more susceptible than freshly formed biofilms. The differences in NCT-mediated killing might not be direct effects since NCT did not react with the monomeric N-acetylglucosamine, but might be explained by denser growth in the PNAG-containing biofilm produced by the wild type strain, which results in delayed penetration of NCT. The higher susceptibility of older biofilms to NCTmediated killing could be explained by more pronounced 3D architecture and subsequent larger surface area for interactions with NCT.

Gentamicin palmitate as a new antibiotic formulation for mixing with bone tissue and local release.

During surgery with bone grafting, the impaction of bone tissue creates an avascular area where local circulation is disrupted. If infections arise, they may prevent systemically administered antibiotics from reaching the infected bone. In this study we evaluated gentamicin palmitate (GP) mixed with gentamicin sulfate (GS) as a coating for bone chips (BCh). The efficacy of the coated BCh was measured by gentamicin base release tests using B. subtilis, S. epidermidis and S. aureus. Gentamicin base release was evaluated in phosphate-buffered saline for up to 7 days using B. subtilis bioassay. Antimicrobial efficacy was tested with S. aureus and S. epidermidis. A significant difference on the release of gentamicin base between GS and GS + GP was observed. S. epidermidis are significantly more susceptible to GS + GP and GS than S. aureus. BCh can act as gentamicin carriers and showed efficacy against S. aureus and S. epidermidis.

Identification and Morphological Characterization of Biofilms Formed by Strains Causing Infection in Orthopedic Implants.

Objectives: For a better understanding of the mechanisms involved in biofilm formation, we performed a broad identification and characterization of the strains affecting implants by evaluating the morphology of biofilms formed in vitro in correlation with tests of the strains' antibiotic susceptibility in planktonic form. The ability of the strains to form biofilms in vitro was evaluated by means of colony forming units counting, metabolic activity tests of biofilm cells, and scanning electron microscopy. Methods: A total of 140 strains were isolated from patients with orthopedic implant-related infections during the period of 2015 to 2018. The identification of the isolates was carried out through microbiological cultures and confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antibiotic susceptibility rates of the isolates were accessed according to EUCAST (European Committee on Antimicrobial Susceptibility Testing). The ability of all isolates to form biofilms in vitro was evaluated by counting the colony forming units, by measuring the metabolic activity of biofilm cells, and by analyzing the morphology of the formed biofilms using scanning electron microscopy. Results: From all the isolates, 41.84% (62 strains) were Staphylococcus epidermidis and 15.60% (22 strains) were Staphylococcus aureus. A significant difference in the capacity of biofilm formation was observed among the isolates. When correlating the biofilm forming capacity of the isolates to their antibiotic susceptibility rates, we observed that not all strains that were classified as resistant were biofilm producers in vitro. In other words, bacteria that are not good biofilm formers can show increased tolerance to multiple antibiotic substances. Conclusion: From 2015 until 2018, Staphylococcus epidermidis was the strain that caused most of the orthopedic implant-related infections in our hospital. Not all strains causing infection in orthopedic implants are able to form biofilms under in vitro conditions. Differences were observed in the number of cells and morphology of the biofilms. In addition, antibiotic resistance is not directly related to the capacity of the strains to form biofilms in vitro. Further studies should consider the use of in vitro culture conditions that better reproduce the joint environment and the growth of biofilms in humans.

Cerebrospinal fluid impairs antimicrobial activity of fosfomycin in vitro.

OBJECTIVES: Fosfomycin penetrates well into cerebrospinal fluid (CSF) and is considered for treatment of infections of the central nervous system (CNS). This study evaluated the influence of human CSF on the antimicrobial activity of fosfomycin. METHODS: Time-kill curves were performed in Mueller-Hinton broth (MHB) and in pooled human CSF using fosfomycin concentrations ranging from 0.25x to 8x MIC for a clinical Staphylococcus aureus isolate. To estimate the activity of fosfomycin at the target site, the concentration-time curve measured in CSF of a patient at steady state was simulated in vitro in human CSF using two S. aureus isolates. RESULTS: In CSF a higher fosfomycin concentration (8x MIC) was required to achieve sustained bacterial killing than in MHB (1x MIC). In vitro simulation of the pharmacokinetic profile measured in CSF of the selected patient showed initial killing, but terminal re-growth of both test strains. CONCLUSIONS: The antibacterial activity of fosfomycin is lower in CSF than in MHB, and drug concentrations slightly exceeding the MIC may not be sufficient to achieve bactericidal effects in the CNS.

Antibiotic resistance of blood cultures in regional and tertiary hospital settings of Tyrol, Austria (2006-2015): Impacts & trends.

Blood stream infections rank among the top seven causes of death of the general population. The aim of our study was to better understand the epidemiology of BSI in order to improve diagnostics and patient outcome. We used retrospective aggregated laboratory data of blood samples received from all public hospitals in Tyrol, Austria between 2006 and 2015. Microorganisms were categorized into obligatory, facultative, unusual pathogens and contaminants. The distribution, the cumulative incidence and antimicrobial susceptibility patterns were compared between the tertiary (TH) and regional peripheral hospitals (PH). Among 256,364 blood samples, 76.1% were from the TH The incidence of obligatory pathogens was 1.7 fold, and up to 3 times higher for facultative, unusual pathogens and contaminants in the TH and increased mainly due to an increase of E.coli, which was the most common isolated pathogen (n = 2,869), followed by Staphylococcus aureus (n = 1,439), Enterococcus sp. (n = 953) and Klebsiella sp. (n = 816). The distribution of obligatory pathogens differed between the hospital settings: In the TH Enterococcus sp. accounted for 40.8% and E.coli for 70.4%, respectively, whereas in the PH for 25.4% (p<0.0001) and 57.8%, respectively (p<0.0001) Antibiotic resistance of Gram negative bacteria and Staphylococcus aureus did not change during the observation period. Carbapenem resistance of Klebsiella sp. and vancomycin and linezolid resistance of Enterococcus faecium showed a non-significant increase since 2010 in the TH setting. We concluded that the incidence of BSI in TH was higher compared to PH. We observed higher contamination rates in the TH. We could not interpret the data of coagulase negative staphylococci due to lack of clinical data. We strongly recommend enhancement of training on blood culture sampling to decrease the rate of contamination. Due to differences in pathogen distribution and antimicrobial resistance between different hospital settings we recommend separate treatment guidelines for BSI by hospital setting.

Activities of antifungal agents against yeasts and filamentous fungi: assessment according to the methodology of the European Committee on Antimicrobial Susceptibility Testing.

We compared the activities of antifungal agents against a wide range of yeasts and filamentous fungi. The methodology of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for yeasts and spore-forming molds was applied; and a total of 349 clinical isolates of Candida spp., other yeast species, Aspergillus spp., and nondermatophyte non-Aspergillus spp. were investigated. The average geometric mean (GM) of the MICs of the various drugs for Candida spp. were as follows: amphotericin B (AMB), 0.55 microg/ml; liposomal amphotericin B (l-AMB); 0.35 microg/ml; itraconazole (ITC), 0.56 microg/ml; voriconazole (VRC), 0.45 microg/ml; posaconazole (POS), 0.44 microg/ml; and caspofungin (CPF), 0.45 microg/ml. The data indicated that the majority of Candida spp. were susceptible to the traditional and new antifungal drugs. For Aspergillus spp., the average GM MICs of AMB, l-AMB, ITC, VRC, POS, and CPF were 1.49 microg/ml, 1.44 microg/ml, 0.65 microg/ml, 0.34 microg/ml, 0.25 microg/ml, and 0.32 microg/ml, respectively. For the various zygomycetes, the average GM MICs of AMB, l-AMB, ITC, and POS were 1.36 microg/ml, 1.42 microg/ml, 4.37 microg/ml, and 1.65 microg/ml, respectively. Other yeastlike fungi and molds displayed various patterns of susceptibility. In general, the minimal fungicidal concentrations were 1 to 3 dilutions higher than the corresponding MICs. POS, AMB, and l-AMB showed activities against a broader range of fungi than ITC, VRC, and CPF did. Emerging pathogens such as Saccharomyces cerevisiae and Fusarium solani were not killed by any drug. In summary, the EUCAST data showed that the in vitro susceptibilities of yeasts and filamentous fungi are variable, that susceptibility occurs among and within various genera and species, and that susceptibility depends on the antifungal drug tested. AMB, l-AMB, and POS were active against the majority of pathogens, including species that cause rare and difficult-to-treat infections.

Plasma protein binding of fluoroquinolones affects antimicrobial activity.

OBJECTIVES: In contrast to most antimicrobial classes, there is a doubt about the impact of protein binding (PB) on the antimicrobial activity of fluoroquinolones. We set out to evaluate the suitability of previously used models for investigating the influence of PB on bacterial killing by fluoroquinolones. METHODS: PB of moxifloxacin and trovafloxacin was determined in Mueller-Hinton broth (MHB) containing different concentrations of human serum or albumin. Bacterial growth curves of Staphylococcus aureus and Pseudomonas aeruginosa were determined in pure serum, pure MHB and MHB containing different amounts of serum or albumin. Killing of both strains at concentrations equal to the MIC was investigated for moxifloxacin and trovafloxacin in MHB and also in medium that showed PB values identical to those of pure serum. RESULTS: Frequently used media for investigating the impact of PB, i.e. MHB containing 20% to 70% serum or 4% albumin, did not reach the level of PB achieved in pure serum or significantly hampered bacterial growth compared with pure MHB. PB in MHB containing 12% albumin was identical to that in pure serum but did not impair bacterial growth. Addition of 12% albumin significantly reduced bacterial killing by both fluoroquinolones compared with that found in pure MHB. CONCLUSIONS: For fluoroquinolones, standard media might be insufficient to investigate the impact of PB on bacterial killing. MHB containing 12% albumin seems to be a promising medium in this context. For moxifloxacin and trovafloxacin, PB leads to significant reduction of antimicrobial activity.

Antimicrobial activity of cefepime and rifampicin in cerebrospinal fluid in vitro.

OBJECTIVES: Though used for infections of the central nervous system, the pharmacodynamics of antimicrobial agents is commonly evaluated only in commercially available bacterial growth media. In the present study, the effects of cerebrospinal fluid (CSF) on bacterial killing by cefepime and rifampicin were investigated. METHODS: CSF was collected from patients who did not receive antibiotics. Time-kill curves were performed over 24 h using drug concentrations of 0.25-, 0.5-, 1-, 2-, 4- and 8-fold the respective MIC for the Staphylococcus aureus test strain. Killing curves were performed in Mueller-Hinton broth (MHB), in CSF incubated in ambient air (CSF(AIR)) and in CSF in air with 5% CO(2) (CSF(CO(2))). CO(2) served to adjust the pH of CSF to physiological values. RESULTS: Sustained bacterial killing was achieved by cefepime at lower drug concentrations in CSF(CO(2)) than in MHB. In contrast, rifampicin concentrations above the MIC were required to exert sustained killing in CSF(CO(2)). Both drugs were least effective in CSF(AIR). CONCLUSIONS: Standard susceptibility tests may lead to over- or underestimation of the activity of distinct antibiotics in CSF. Evaluation of the antimicrobial activity in pH-adjusted CSF can provide useful information on drugs considered for the treatment of bacterial infections residing in CSF.

Acute nosocomial urinary tract infection in children.

The spectrum and antimicrobial susceptibilities of pathogens causing acute nosocomial urinary tract infection in hospitalized pediatric patients were revealed to be heterogeneous. Therefore, to avoid the failure of empirical antimicrobial therapy in these patients, underlying disease and previous antimicrobial treatment have to be considered.

Enterocolitis due to simultaneous infection with rotavirus and Clostridium difficile in adult and pediatric solid organ transplantation.

Diarrhea is a well-known complication of immunosuppression but is also frequently caused by pathogens such as Clostridium difficile (CD) and rotavirus (RV). Three adult and five pediatric solid organ recipients (SORs) developed diarrhea with simultaneous identification of CD and RV. Rotavirus was identified using an immunochromatografic- or enzyme-linked immunosorbent assay; CD was identified using a rapid immunoassay or enzyme immunoassay. One adult renal, one adult kidney-pancreas, one adult liver, and five pediatric liver recipients were affected. Onset of RV/CD infection ranged from 2 weeks to 4 years posttransplant. All patients presented with enterocolitis causing significant fluid and electrolyte loss. In adults, CD was treated with metronidazole and in children with oral vancomycin. RV infection was treated with fluid/electrolyte replacement. During diarrhea, a significant rise in tacrolimus serum level was noted. All patients cleared CD. One child developed recurrent episodes of RV infection and died from bacterial sepsis; the renal recipient died 6 months posttransplant from myocardial infarction. The remaining six patients are currently alive with well-functioning grafts. Simultaneous infection with CD and RV may lead to severe diarrhea in SORs. Both pathogens should be considered in SOR presenting with diarrhea.

Treatment of destructive aortic valve endocarditis with the Freestyle Aortic Root Bioprosthesis.

BACKGROUND: Successful treatment of destructive aortic valve endocarditis with annular abscess formation requires extensive surgical debridement and reconstruction of the left ventricular outflow tract and aortic root. Homograft aortic roots are the conduits of choice, but because they are not available in all cases, alternative conduits are needed. METHODS: Owing to its features, which are comparable to those of homografts, the Freestyle aortic root xenograft was used in 10 consecutive patients aged between 32 and 77 years. All patients had extensive abscess formation, 5 presented with prosthetic valve endocarditis, 2 had additional mitral valve endocarditis requiring partial leaflet resection and reconstruction, 1 patient had an additional fistula into the right atrium, and 1 required coronary bypass. One patient developed a septic ventricular septal defect and fistula into the right atrium with tricuspid valve endocarditis. RESULTS: None of the patients required reoperation for bleeding. Two (20%) patients died in the postoperative period, 1 due to multiorgan failure, and 1 due to preexisting invasive pulmonary aspergillosis. At autopsy, neither had evidence of intrapericardial hematoma or suture dehiscence. One patient died 13 months postoperatively without clinical signs of valve dysfunction or recurrent endocarditis. All other patients are well at 12 to 42 months after surgery. Clinical examination and echocardiography at the most recent follow-up showed no signs of valve dysfunction, recurrent fistulation, or endocarditis. CONCLUSIONS: The Freestyle aortic root appears to be an acceptable alternative to homografts in the treatment of severe endocarditis. Long-term valve durability in younger patients, however, remains to be determined.

Bactericidal activity of herbal extracts.

The antimicrobial activity of total herbal extracts has been investigated. The MIC of extracts of Evodia rutaecarpa and grape kernel ranged between 0.25 and 1 mg/ml against gram-positive cocci and P. aeruginosa. Cocci were killed after 30-90 min of incubation in grape kernel extract (0.5-1.5 mg/ml), and after 8 h in evodia extract (0.5-1 mg/ml), respectively. C. albicans was only susceptible to evodia (MIC 0.5 mg/ml). The organic solvents of the preparations contributed to the antibacterial effect of herbal extracts with MICs of ethanol between 4 and 10 vol% and those of methanol between 6 and 10 vol%. Taking this into consideration, mastic and thyme extracts exerted hardly any microbicidal activity, while grape kernel extract and evodia were still effective at 2- to 6-fold dilutions below the MIC of the solvent. Because of the weak antimicrobial activity of total herbal extracts we recommend to give preference to preparations of single or more purified compounds.

Efficacy of antibacterial bioactive glass S53P4 against S. aureus biofilms grown on titanium discs in vitro.

We evaluated the effectiveness of different sizes of bioactive glass S53P4 against Staphylococcus aureus biofilms grown on metal discs in vitro. S. aureus biofilms were cultivated on titanium discs. BAG-S53P4 (0.5-0.8 mm and <45 µm) were placed in contact with the discs containing biofilms. Glass beads (0.5 mm) were used as a control. After each interval, the pH from each sample was measured. Colony forming units were counted for the biofilm recovery verification. In parallel, we tested the activity of bioactive glass against S. aureus planktonic cells. We found that BAG-S53P4 can suppress S. aureus biofilm formation on titanium discs in vitro. The suppression rate of biofilm cells by BAG-S53P4 <45 µm was significantly higher than by BAG-S53P4 0.5-0.8 mm. BAG-S53P4 has a clear growth-inhibitory effect on S. aureus biofilms. BAG-S53P4 <45 µm is more efficient against biofilm growth in vitro comparing with BAG-S53P4 0.5-0.8 mm. Bioactive glass S53P4 has potential to be used as bone substitute for the resolution of infection complications in joint replacement surgeries and treatment of chronic osteomyelitis.

Effect of freezing on the release rate of gentamicin palmitate and gentamicin sulfate from bone tissue.

In this study we evaluated gentamicin palmitate salt and gentamicin sulfate salt mixed with bone chips after storage at -80°C. Different concentration rates of gentamicin sulfate and gentamicin palmitate were mixed with human bone chips and stored for 1-6 months at -80°C. Nonstored samples were used as control. The release of the antibiotics from the bone was carried out in phosphate-buffered saline. Antibiotic concentrations in the elutions were determined with microbiological agar diffusion assay using Bacillus subtilis. Susceptibility tests were carried out using Staphylococci strains. The rate of gentamicin base (GB) released from bone was similar for all gentamicin salts and all storage conditions. The elutions released were efficient on reducing S. aureus and S. epidermidis CFU during all storage time. In resume, the capacity of bone grafts to act as gentamicin carriers has been confirmed in this study. GS + GP showed equivalent efficacy against S. aureus and S. epidermidis compared with GS pure. The lower delivery rate of GS + GP, related to its affinity with fat tissue can be an advantage for longer release times, increasing the local protection against infections. Storage at -80°C does not interfere on the gentamicin salts activity used.

Calcium carbonate powder containing gentamicin for mixing with bone grafts.

Bone grafts are used for reconstructing bone defects caused by implant-associated complications, trauma, and tumors. Surgery with bone allografts is complex and time consuming; therefore, it is prone to a higher infection rate (2.0%-2.5%). In the case of site infection, systemically administered antibiotics cannot reach the infected bone graft. This study evaluated the use of resorbable bone graft substitute powder (HERAFILL; Heraeus Medical GmbH, Wehrheim, Germany) as a bone void-filling material as well as an antibiotic carrier for mixing with bone grafts. The antibiotic activity of the bone chips mixed with HERAFILL powder was measured by drug release tests and bacterial susceptibility with Bacillus subtilis, Staphylococcus epidermidis, and Staphylococcus aureus. HERAFILL powder was added to the bone chips (bone chips/HERAFILL; w/w = 1:1), mixed with a spatula, and vortexed for 1 minute. Gentamicin base release was evaluated in phosphate-buffered saline for up to 7 days using B subtilis bioassay. Antimicrobial efficacy was tested with S aureus and S epidermidis. The average amount of gentamicin base released from bone chips mixed with HERAFILL at 0 to 12 hours was 99.66 mg/mL. On day 7, the gentamicin base released 0.42 mg/mL. The elution released from bone chips mixed with HERAFILL promoted the formation of a zone of inhibition on S epidermidis and S aureus plates. This study confirmed the capacity of bone grafts to act as antibiotic carriers once mixed with HERAFILL powder. Bone chips mixed with HERAFILL showed efficacy against S aureus and S epidermidis.

Sepsis otopathy: experimental sepsis leads to significant hearing impairment due to apoptosis and glutamate excitotoxicity in murine cochlea.

Hearing loss is frequent in intensive care patients and can be due to several causes. However, sepsis has not been examined as a possible cause. The aim of this study is to assess the influence of experimental sepsis on hearing thresholds and to evaluate pathological changes in the cochlea. The cecal ligation puncture technique was used to induce sepsis in 18 mice. Results were compared with those from 13 sham-operated and 13 untreated control mice. The hearing thresholds of the animals were evaluated with auditory evoked brainstem responses prior to the induction of sepsis and again at the peak of the disease. Immediately after the second measurement, the mice were sacrificed and the inner ears harvested and prepared for further evaluation. The cochleae were examined with light microscopy, electron microscopy and immunohistochemistry for Bax, cleaved caspase-3 and Bcl-2. The mice with sepsis showed a significant hearing loss but not the control groups. Induction of apoptosis could be shown in the supporting cells of the organ of Corti. Furthermore, excitotoxicity could be shown at the basal pole of the inner hair cells. In this murine model, sepsis leads to significant hearing impairment. The physiological alteration could be linked to apoptosis in the supporting cells of the organ of Corti and to a disturbance of the synapses of the inner hair cells.