Synergistic Effect of Silver Nanoparticles with Neomycin or Gentamicin Antibiotics on Mastitis-Causing Staphylococcus aureus

Objective: Mastitis is one of the most costly diseases in dairy cows, which greatly decreases milk production. Use of antibiotics in cattle leads to antibiotic-resistance of mastitis-causing bacteria. The present study aimed to investigate synergistic effect of silver nanoparticles (AgNPs) with neomycin or gentamicin antibiotic on mastitis-causing Staphylococcus aureus. Materials and Methods: In this study, 46 samples of milk were taken from the cows with clinical and subclinical mastitis during the august-October 2015 sampling period. In addition to biochemical tests, nuc gene amplification by PCR was used to identify strains of Staphylococcus aureus. Disk diffusion test and microdilution were performed to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Fractional Inhibitory Concentration (FIC) index was calculated to determine the interaction between a combination of AgNPs and each one of the antibiotics. Results: Twenty strains of Staphylococcus aureus were isolated from 46 milk samples and were confirmed by PCR. Based on disk diffusion test, 35%, 10% and 55% of the strains were respectively susceptible, moderately susceptible and resistant to gentamicin. In addition, 35%, 15% and 50% of the strains were respectively susceptible, moderately susceptible and resistant to neomycin. According to FIC index, gentamicin antibiotic and AgNPs had synergistic effects in 50% of the strains. Furthermore, neomycin antibiotic and AgNPs had synergistic effects in 45% of the strains. Conclusion: It could be concluded that a combination of AgNPs with either gentamicin or neomycin showed synergistic antibacterial properties in Staphylococcus aureus isolates from mastitis. In addition, some hypotheses were proposed to explain antimicrobial mechanism of the combination.

Ligustrazine facilitates hair cell regeneration in the cochlea following gentamicin ototoxicity

BACKGROUND： Ligustrazine （tetramethylpyrazine） decreases ototoxicity induced by gentamicin and facilitates hair cell regeneration and repair, but the precise mechanisms remain controversial.OBJECTIVE： To explore the protective effects of ligustrazine on gentamicin ototoxicity by determining heat shock protein 70 mRNA and protein expression in the cochlear stria vascularis of guinea pigs at different time points.DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the Laboratory of Physiology, Shenyang Medical College of China in 2007.MATERIALS： Ligustrazine parenteral solution （Qiqihar Pharmaceutical Factory, China） and gentamicin sulfate （Shenyang First Pharmaceutical Factory, China） were used in this experiment.METHODS： White guinea pigs with red eyes were randomly intraperitoneally administered gentamicin sulfate injection ＋ saline, gentamicin sulfate injection ＋ ligustrazine, and ligustrazine ＋ saline, respectively.MAIN OUTCOME MEASURES： Auditory brains tern response threshold was measured. Immunohistochemistry, in situ hybridization, and image analyzing techniques were utilized to determine heat shock protein 70 mRNA and protein expression in cochlear stria vascularis of guinea pigs.RESULTS： Following gentamicin ototoxicity, the auditory brainstem response threshold increased, peaked on day 3, and then decreased with increased time after drug withdrawal. The auditory brainstem response threshold was significantly diminished following ligustrazine intervention, but recovered to normal on day 30 （P〉0.05）. Heat shock protein 70 expression also increased, peaked on day 3, and then decreased in the cochlear stria vascularis of guinea pigs following gentamicin ototoxicity. Ligustrazine intervention resulted in decreased heat shock protein 70 expression in the cochlear stria vascularis, which recovered to normal on day 14. Heat shock protein 70 mRNA expression increased in the cochlear stria vascularis following gentamicin ototoxicity, but ligustrazine intervention resulted in decreased levels. CONCLUSION： Ligustrazine significantly ameliorated gentamicin ototoxicity by reducing heat shock protein 70 mRNA and protein expression in the cochlear stria vascularis.

Ultrastructural features of gentamicin-induced glomerular damages in rabbits

In order to clarify whether gentamicin （GM） could damage the renal glomeruli,theultrastructural changes of the renal cortex were observed in rabbits after they received a singleinjection of 100 mg/kg GM or 100 mg·kg-10·d-1 GM for 3 consecutive days.The animals ofthe control group received equal amount of normal saline.It was found that some myelin figuresappeared in the epithelial cells of the proximal tubules as early as 1 h after a single GM injec-tion;severe swelling,degeneration,and obvious changes of the organelles were seen in the en-dothelial cells of the glomerular capillaries,the podocytes and the epithelial cells of the proxi-mal tubules 24 h after an injection of GM;and fusion of the processes of podocytes,thickeningof the glomerular membrane and necrosis of the epithelial cells of a part of the’proximal tubuleswere encountered 24h after the 3rd GM injection.These findings demonstrate that GM can in-jure not only the proximal tubules but also the glomeruli in rabbits.

Pattern of hair cell loss and delayed peripheral neuron degeneration in inner ear by a high-dose intratympanic gentamicin

To gain insights into the ototoxic effects of aminoglycoside antibiotics(AmAn) and delayed peripheral ganglion neuron death in the inner ear.experimental animal models were widely used with several different approaches including AmAn systemic injections,combination treatment of AmAn and diuretics,or local application of AmAn.In these approaches,systemic AmAn treatment alone usually causes incomplete damage to hair cells in the inner ear.Co-administration of diuretic and AmAn can completely destroy the cochlear hair cells,but it is impossible to damage the vestibular system.Only the approach of AmAn local application can selectively eliminate most sensory hair cells in the inner ear.Therefore,AmAn local application is more suitable for studies for complete hair cell destructions in cochlear and vestibular system and the following delayed peripheral ganglion neuron death.In current studies,guinea pigs were unilaterally treated with a high concentration of gentamicin(GM,40 nig/ml) through the tympanic membrane into the middle ear cavity.Auditory functions and vestibular functions were measured before and after GM treatment.The loss of hair cells and delayed degeneration of ganglion neurons in both cochlear and vestibular system were quantified 30 days or 60 days after treatment.The results showed that both auditory and vestibular functions were completely abolished after GM treatment.The sensory hair cells were totally missing in the cochlea,and severely destroyed in vestibular end-organs.The delayed spiral ganglion neuron death 60 days after the deafening procedure was over 50%.However,no obvious pathological changes were observed in vestibular ganglion neurons 60 days post-treatment.These results indicated that a high concentration of gentamycin delivered to the middle ear cavity can destroy most sensory hair cells in the inner ear that subsequently causes the delayed spiral ganglion neuron degeneration.This model might be useful for studies of hair cell regenerations,delayed degeneration of peripheral auditory neurons,and/or vestibular compensation.In addition,a potential problem of ABR recording for unilateral deafness and issues about vestibular compensation are also discussed.

Nephroprotective activity of Solanum xanthocarpum fruit extract against gentamicin-induced nephrotoxicity and renal dysfunction in experimental rodents

Objective:To evaluate nephroprotective potential of Solarium xanthocarpum(S.xanthocarpum) fruit extract(SXE) against gentamicin(GM) induced nephrotoxicity) and renal dysfunction. Methods:Twenty-four Wistar rats were divided into four groups(n=6).Control rats that received normal saline(i.p.) and 0.5%carboxymethyl cellulose(p.o.) per day lor 8 d.Nephrotoxicity was induced in rats by intraperitoneal administration of GM(100 mg/kg/d for 8 d) and were treated with SXE(200 and 400 mg/kg/d(p.o.) for 8 d).Plasma and urine urea and creatinine,kidney weight,urine output,blood urea nitrogen,renal enzymatic and non-enzymatic antioxidants and lipid peroxidation was evaluated along with histopathological investigation in various experimental groupsof rats.Results:It was observed that the GM treatment induced significant elevation(P【0.001) in plasma and urine urea,creatinine,kidney weight,blood urea nitrogen, renal lipid peroxidation along with significant decrement(P【0.001) in urine output,renal enzymatic and non-enzymatic antioxidants.SXE 200 and 400 mg/kg treatment to GM treated rats recorded significant decrement(up to P【0.001) in plasma and mine urea and creatinine, renal lipid peroxidation along with significanl increment(up to P【0.001) in renal enzymatic and non-enzvmatic antioxidants.Histological obsenatioiis of kidney tissues too correlated with the biochemical obsenatioiis.Conclusions:These finding powerfully supports that S,xanthocarpum fruit extract acts in the kidney as a potent scavenger of free radicals to prevent the toxic effects of GM both in the biochemical and histopathological parameters and thus validates its elhnomedicinal use.

Phospholipon 90H(P90H)-based PEGylated microscopic lipospheres delivery system for gentamicin:an antibiotic evaluation

Objective:To formulate gentamicin liposphere by solvent-melting method using lipids and polyethylene glycol 4000(PEG-4000) for oral administration.Methods:Gentamicin lipospheres were prepared by melt-emulsification using 30%w/w Phospholipon(?) 90H in Beeswax as the lipid matrix containing PEC-4000.These lipospheres were characterized by evaluating on encapsulation efficiency,loading capacity,change in pH and the release profile. Antimicrobial activities were evaluated against Escherichia coli,Pseudomonas aeruginosa. Salmonella paratyphii and Staphylococcus aureus using the agar diffusion method.Results: Photomicrographs revealed spherical particles within a micrometer range with minimal growth after 1 month.The release of gentamicin in vitro varied widely with the PEC-4000 contents. Moreover,significant(P>0.05) amount of gentamicin was released in vivo from the formulation. The encapsulation and loading capacity were all high,indicating the ability of the lipids to take up the drug.The antimicrobial activities were very high especially against Pseudomonas compare to other test organisms.This strongly suggested that the formulation retain its bioactive characteristics.Conclusions:This study strongly suggest that the issue of gentamicin stability and poor absorption in oral formulation could be adequately addressed by tactical engineering of lipid drug delivery systems such as lipospheres.

The impact of storage conditions upon gentamicin coated antimicrobial implants

A systematic approach was developed to investigate the stability of gentamicin sulfate(GS) and GS/poly(lacticco-glycolic acid)(PLGA) coatings on hydroxyapatite surfaces.The influence of environmental factors(light,humidity,oxidation and heat) upon degradation of the drug in the coatings was investigated using liquid chromatography with evaporative light scattering detection and mass spectrometry.GS coated rods were found to be stable across the range of environments assessed,with only an oxidizing atmosphere resulting in significant changes to the gentamicin composition.In contrast,rods coated with GS/PLGA were more sensitive to storage conditions with compositional changes being detected after storage at 60 °C,75% relative humidity or exposure to light.The effect of γ-irradiation on the coated rods was also investigated and found to have no significant effect.Finally,liquid chromatography–mass spectrometry analysis revealed that known gentamines C_1,C_1 aand C_2were the major degradants formed.Forced degradation of gentamicin coatings did not produce any unexpected degradants or impurities.

Anti-inflammatory, anti-oxidative and anti-apoptotic effects of Heracleum persicum L. extract on rats with gentamicin-induced nephrotoxicity

Objective:To evaluate the effect of Heracleum persicum L.against gentamicin-induced nephrotoxicity in rats.Methods:Thirty-six Wistar rats were divided into 6 groups including control(normal saline),gentamicin(80 mg/kg/d for 10 d),Heracleum persicum(750 mg/kg/d),and gentamicin(10 d)+Heracleum persicum extract at three different doses(250,500,and 750 mg/kg/d for 40 d).Urine creatinine,urea,protein,and albumin levels were determined.In addition,serum urea,creatinine,sodium,potassium,cytokines(TNF-α,IL-1β,IL-6,and IL-10),glutathione peroxidase activity,total antioxidant capacity,kidney malondialdehyde,stereological parameters,and expressions of apoptosis-related genes(p53,Bax,Bcl-2,and caspase-3)were measured.The LD50 of Heracleum persicum extract was determined based on Lorke’s method.Histopathological evaluation was also performed.Results:In addition to decreased urine protein and albumin,and increased creatinine and urea,co-treatment with gentamicin and Heracleum persicum significantly reduced levels of creatinine and urea,and increased sodium and potassium in serum.Heracleum persicum treatment also improved stereological parameters and serum inflammatory cytokines.There was a significant increase in serum glutathione peroxidase activity and total antioxidant capacity as well as a reduction in malondialdehyde level.Furthermore,treatment with Heracleum persicum extracts downregulated p53,caspase-3,and Bax and upregulated Bcl-2 expressions.In histopathological evaluation,Heracleum persicum extracts showed protection against gentamicin-induced renal damages.Conclusions:Heracleum persicum exhibits protective effects against gentamicin-induced structural and functional renal impairments.

A study of gentamicin injury mechanisms using cultured mouse cochlear spiral ganglion cells

Objective To study gentamicin injury mechanisms using postnatal mouse cochlear spiral gangcells （SGC）. Methods SGCs were isolated using a combinatorial approach of enzymatic digestion and mechanical separation from P2 - 6 Kunming mouse cochleae. After 4 days, cultured SGCs were fixed with 4% paraformaldehyde at room temperature for immunocytochemical examination using the methods of S-P and the monoclonal antibody against mouse neurofilament protein （Neurofilament-68/200Kda, NF-L＋ H）. SGCs were randomly divided into a blank control group and three gentamicin treatment groups （medium gentamicin concentration at 50 mg/L, 100 mg/L and 150 mg/L respectively）, SGCs were collected and examined under a transmission electron microscope after being cultured for 48 h. Results SGC primary culture was successful. SGC cytoplasm and neurites were dyed brownish yellow by the monoelonal mouse neurofilament protein antibody. SGCs showed classical bipolar neuron appearance. Under the transmission electron microscope,.gentamicin treated SGCs showed morphological features different compared to those in the blank control group, which might indicate apoptosis. Conclusion Our results indicate that gentamicin has direct toxic effects on cochlear SGCs in mice and the injury mechanism is closely related with apoptosis. Damage to mitochor, dria may play an important role in the process.

蝉花菌丝体对大鼠Gentamicin肾损伤之保护作用

Gentamicin被用于治疗由革兰氏阴性菌所引起的致命性感染,然而,因gentamicin有较强的肾毒性,能抑制肾脏细胞蛋白质的合成,所以易导致急性肾衰竭的发生。蝉花(Cordycepscicadae)为名贵传统中药材,具有保护肾功能等多样生理功效。本篇研究分为三个部分,我们首先比较两株虫草属真菌–蝉花及禅草(Cordyceps cicadicola),何者对于gentamicin诱导之急性肾损伤有较好的预防功效;接着,我们评估发酵时间长短对于蝉花之肾脏保护功能有无影响;第三部分则进行蝉花对于gentamicin诱导之急性肾损伤的剂量效应评估。试验期间每日进行实验动物之临床观察并测量动物体重,并于试验结束时取大鼠血液、尿液及脏器进行血清生化学检查、尿液分析及组织病理学检查。试验结果显示,蝉花菌丝体对于gentamicin诱导之急性肾损伤大鼠有良好预防功效。

Postoperative multidrug-resistant Acinetobacter baumannii meningitis successfully treated with intravenous doxycycline and intraventricular gentamicin: A case report

BACKGROUND Multidrug-resistant Acinetobacter baumannii(MDRAB) has emerged as an increasingly important pathogen that causes nosocomial meningitis. However,MDRAB-associated nosocomial meningitis is rarely reported in children.CASE SUMMARY We report the case of a 1-year-old girl with a choroid plexus papilloma, who developed postoperative nosocomial meningitis due to MDRAB. The bacterial strain was sensitive only to tigecycline and colistin, and showed varying degrees of resistance to penicillin, amikacin, ceftriaxone, cefixime, cefotaxime,ciprofloxacin, levofloxacin, gentamicin, meropenem, imipenem, and tobramycin.She was cured with intravenous doxycycline and intraventricular gentamicin treatment.CONCLUSION Doxycycline and gentamicin were shown to be effective and safe in the treatment of a pediatric case of MDRAB meningitis.

Floral extract of Tecoma stans:A potent inhibitor of gentamicin-induced nephrotoxicity in vivo

Objective:To highlight the nephroprotective activity of ethyl acetate extract of dried flowers of Tecomu stans for its protective effects on genlamicin-induced nephrotoxicity in albino rats. Methods:For studying acute toxicity study,single oral dose of 5（KM） mg ethyl acetate floral extract/kg hodv weight was administered to albino rats（five females,five males）.Nephrotoxicity was induced in albino rats by intraperitoneal administration of gentamicin 80 mg/kg/day for eight days.Effect of concurrent administration of ethyl acetate floral extract of Tecoma stans at a dose of 100.200 and 300 mg/kg/day given by oral mute was determined using serum creatinine,serum uric acid,blood urea nitrogen and serum urea as indicators of kidney damage.The study groups contained six rats in each group.As nephrotoxicity of gentamicin is known to involve induction of oxidative stress,in vitro antioxidant aclivity and free radical-scavenging activity of this extract was also evaluated.Results:For acute toxicity testing both female and male rats administered with the extract at a dose of 5 000 mg/kg.The results showed no toxicity in terms of general behavior change,mortality,or change in gross appearance of internal organs(LD50】5 000 mg/kg). It was observed that the ethyl acetate floral extract of Tecoma stans significantly protected rat kidneys from gentamicin-induced histopathological changes.Gentamicin-induced glomerular congestion,peritubular and blood vessel congestion,epithelial desquamation,accumulation ol inflamnialoiy cells and necrosis of the kidney cells were found to be reduced in the groups receiving the ethyl acetate floral extract of Tecoma starts along with gentamicin in a dose dependent manner.The floral extract also reduced the gentamicin-induced increase in serum creatinine,serum uric acid,blood urea nitrogen and serum urea levels（P】0.01）.Conclusions: The present study indicates a verv important role of reactive oxygen species（BOS） and the relation to renal dysfunction and point to the therapeutic potential of Tecoma stans in gentamicin induced nephrotoxicity.

Effect of nettle(Urtica dioica) extract on gentamicin induced nephrotoxicity in male rabbits

Objective:To investigate the antioxidant ef ect of an orally administered ethanol extract of nettle(Urtica dioica) and its protective role in preventing or ameliorating oxidative stress as a major factor in gentamicin-induced nephrotoxicity in male rabbits. Methods: Twenty rabbits were divided into 4 equal groups:(G1) control group,(G2) gentamicin treated group(100 mg/kg),(G3) nettle treated group(100 mg/kg),(G4) combination treated group with both gentamicin(100 mg/kg) and nettle(100 mg/kg) for 10 days. The antioxidant properties of nettle were evaluated using dif erent antioxidant tests, such as determination of glutathione and malondialdehyde levels and total phenolic content analysis. Results: Biochemical and histopathological study revealed that gentamicin caused nephrotoxicity observed clearly in the histopathological section of the kidney in the gentamicin treated group. Serum creatinine and blood urea nitrogen were biochemical indicators for nephrotoxicity which increased signii cantly in gentamicin treated group; other groups have no signii cant change in these two parameters. Nettle extract protected the rabbits from alteration in the level of blood urea nitrogen and serum creatinine when given after inducing of gentamicin nephrotoxicity. The nettle treated group showed a great ef ect as an antioxidant factor by increasing the glutathione level and reducing malondialdehyde level. No signii cant changes in biochemical parameters and no renal histopathological changes observed in the groups treated with nettle extract, which meant nettle had powerful antioxidant activity. Conclusions: Therefore, it can be assumed that the nephroprotective ef ect shown by nettle in gentamicin-induced nephrotoxicity can reserve intracellular levels of biological pathways and supportively enhance excretion of toxic levels of gentamicin.

Effects of gentamicin on choline acetyltransferase expression in paraolivary nucleus neurons of guinea pigs

BACKGROUND： It is generally accepted that gentamicin can damage the cochlear nerve and acoustic nerve. In recent years, scholars have focused on neuronal changes and neurochemical information in the brainstem primary auditory center. OBJECTIVE： To explore morphological changes of choline acetyltransferase （ChAT）-positive neurons in the paraolivary nucleus （PON） of guinea pigs, and the effect on hearing following gentamicin injection. DESIGN, TIME AND SETTING： Randomized grouping and morphological observational study was performed at Animal Experimental Center of General Hospital of Shenyang Military Area Command of Chinese PLA from January to August 2007. MATERIALS： A total of 48 healthy guinea pigs were randomly divided into model （n = 40） and control （n = 8） groups. The model group was divided into five subgroups at five time points of 1 and 3 days, 1, 2, and 3 weeks. METHODS： Guinea pigs in the model group were intraperitoneally injected with gentamicin, and those in the control group were intraperitoneally injected with the same volume of saline. MAIN OUTCOME MEASURES： Auditory brainstem-evoked potential was used to record auditory threshold; distribution and morphological changes of ChAT-positive neurons in the PON were observed with immunohistochemistry; section area and gray value of ChAT-positive neurons were measured with Quantimet 570 image-analyzing system. RESULTS： ChAT-positive neurons were diffusedly distributed in the PON. The majority was composed of large, round cells, with positive neurites that could be clearly observed. Following gentamicin injection, the positive neurons displayed an irregular outline, and their neurites began to shorten and disappear. The gray value increased with prolonged gentamicin administration （P 〈 0.05）. In addition, the somatic cross-sectional area was enlarged in the model group at 1 and 3 days after injection （P 〈 0.05）, whereas cell number significantly decreased at ;three weeks after injection （P 〈 0.05）. Starting at 3-4 days, behavioral features and auditory degrees became gradually aggravated with prolonged gentamicin administration （P 〈 0.05）. CONCLUSION： Gentamicin damaged ChAT-positive neurons in the PON, and long-term gentamicin treatment aggravated hearing impairment.

Allolobophora caliginosa coelomic fluid ameliorates gentamicin-induced hepatorenal toxicity in rats

Objective:To explore the efficacy of earthworm’s coelomic fluid against gentamicin-induced hepatic and renal toxicity in rats.Methods:The animals were divided randomly into three groups(n=6 per group):control,gentamicin,and Allolobophora caliginosa coelomic fluid-treated groups.Toxicity was established after injection of gentamicin daily for 8 days at a dose of 100 mg/kg.Aspartate aminotransferase,alanine aminotransferase,alkaline phosphatase,total proteins,albumin,creatinine,urea,uric acid,malondialdehyde,glutathione,catalase and histopathology of tissues were investigated in the study.Results:Allolobophora caliginosa coelomic fluid significantly decreased urea,creatinine,uric acid,alanine aminotransferase,aspartate aminotransferase,alkaline phosphatase,and malondialdehyde levels while significantly increasing levels of total proteins,albumin,glutathione and catalase.The histopathological investigation showed partial restoration of renal and hepatic architecture.Conclusions:This study shows the potency of Allolobophora caliginosa coelomic fluid in improving the biochemical and histopathological changes induced by gentamicin in the liver and kidney of the rats.

Toxicological evaluation and protective effect of ethanolic leaf extract of Launaea taraxacifolia on gentamicin induced rat kidney injury

Objective: To evaluate the toxic potential of Launaea taraxacifolia leaf extract(LTE) in rats within 14 d of oral administration and also assess the potential of LTE in protecting against kidney injury induced by gentamicin using rat model.Methods: The protective ability of LTE was done after sub-acute toxicity evaluation has been carried out. Acute Kidney Injury(AKI) was induced by gentamicin at a dose of 160 mg/kg intraperitoneal i.p. Parameters and indicators considered include mortality,clinical signs, body and organ weights, haematological and clinical chemistry parameters.Gross examination and histopathological assessment was also done on selected internal organs.Results: There were no treatment-related deaths or changes in clinical signs, haematological and clinical chemistry indices during sub-acute toxicity studies with the exception of creatinine levels. This was confirmed by micrographs obtained from histopathological analysis. Co-administration of LTE with 160 mg/kg of gentamicin(i.p) markedly decreased the levels of urea and creatinine when compared to negative control group.Histological studies of kidney tissues showed an insignificant change in tubular epithelium in LTE plus gentamicin treated group compared to LTE treated only.Conclusions: Data obtained show that ethanolic leaf extract of Launaea taraxacifolia is non-toxic within a 14 d administration at a maximum dose of 1 000 mg/kg bwt and also possesses the ability to protect against gentamicin-induced kidney damage in rats at a dose of 300 mg/kg bwt.

Preliminary study on synergistic combinations of raw honey with gentamicin against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa of veterinary origin

Objective:To search for further synergistic combinations of gentamicin and raw honey that might have potential in treating wounds.Methods:The antibacterial activity and synergistic interaction of raw honey and gentamicin was assessed by using agar well diffusion method.Two Gram-negative(Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 2154)bacteria were selected for antibacterial activity assay.The cultures of bacteria were maintained in their appropriate agar slants at 4°C throughout the study and used as stock cultures.Results:Raw honey and gentamicin interacted synergistically to inhibit Escherichia coli and Pseudomonas aeruginosa.Conclusions:These results suggest that combinations of raw honey and gentamicin have therapeutic benefits in prophylaxis of infections caused by multidrug-resistant Gram-negative bacilli.

Prevention of Staphylococcus aureus biofilm formation on metallic surgical implants via controlled release of gentamicin

Implant associated infections are a critical health concern following orthopaedic surgery. Sustained local delivery of antibiotics has been suggested as a means of preventing these infections. Poly(D,L-lactide) (PDLLA) is a biodegradable polymer that has been used to coat implants for the delivery of antibiotics and other bioactive molecules. While effective, these studies show that antibiotics are released in a burst profile. Here we evaluated a method for controlled release of gentamicin from implant surfaces using the palmitate alkyl salt to decrease its solubility in aqueous solution. Steel Kirschner wires (K-wires) were coated with Gentamicin-palmitate (GP)-PDLLA, gentamicin sulphate (GS)-PDLLA or vancomycin sulphate (VS)-PDLLA, and elution of antibiotics from coated K-wires investigated using HPLC/MS/ MS. In contrast to burst antibiotic release from the GS-PDLLA and VS-PDLLA groups, GP was released in a slower sustained manner. Colonisation and initial attachment of Staphylococcus aureus Xen29 to gentamicin-coated K-wires was reduced by 90% when compared to the non-coated control group. However there was no statistical difference in recovery of bacteria from GS or GP groups. Bacteria recovered from VS-PDLLA coated K-wires decreased by 36%. Bioluminescence emitted by S. aureus Xen29 was also reduced over seven days in the antibiotic control groups, demonstrating that growth and biofilm development over the longer term was impaired by antibiotic-PDLLA coating. These results indicate that using alkyl salts of antibiotics may be an effective strategy for controlling the release of antibiotics from implants.

Kinetics of Elution of Gentamicin from a Gentamicin-Loaded PMMA Bone Cement

Antibiotic-loaded poly (methyl methacrylate) bone cement (ALBC) is widely used for anchoring joint replacements as a means of reducing the potential for peri-prosthetic joint infection (primary cases) and treating a patient who has an infected joint replacement (revision cases). One shortcoming of the cement is the high maximum exothermic temperature experienced upon polymerization (Tmax), a phenomenon that, it has been postulated, may cause or be implicated in thermal necrosis of peri-prosthetic tissues. There are many reports in the literature on methods of reducing Tmax, with one such study involving the addition of a phase change material (microencapsulated paraffin) (MEPAR) to the cement powder or adding a chain-stopping chemical (1-dodecyl mercaptan) (DDM) to the liquid. In that report, the results of gentamicin elution tests were presented. In the present work, those results were used to calculate various indices of gentamicin elution kinetics, namely 1) diffusion coefficient (Dgent);and 2) values of the coefficients in four equations that are widely used to model antibiotic elution from ALBCs. We found 1) the difference in Dgent of either a MEPAR- or DDM-containing formulation, on the one hand, and that of the control cement, on the other, was not significant;and 2) a consistent trend in the value of only one coefficient in one of the four model equations, with this change suggesting insignificant difference in gentamicin elution mechanism between an experimental cement formulation and the control cement. The implications of these findings for guiding selection of additives that simultaneously produce significant reduction of Tmax but minimal effect on gentamicin elution kinetics are discussed. This guide is a novel contribution to the literature.

Novel genomic biomarkers for acute gentamicin nephrotoxicity in dog

Objectives: Novel biomarkers indicative of drug-induced kidney injury (DIKI) in dogs would have significant application in preclinical drug development. We conducted a feasibility study to identify genomic expression profiles for monitoring progressive, acute DIKI in dogs. Materials and Methods: Animals were intramuscularly administered either 0.9% physiological saline or gentamicin (40 mg/kg/day) for 10 consecutive days and euthanized on day 11. Serum and urine samples were collected at various time points and kidney samples were collected at necropsy for biomarker measurements. Results: Acute gentamicin-induced renal histopathology changes were localized to the proximal convoluted tubules and characterized as slight-to-marked, diffuse cortical-medullary tubular epithelial degeneration/necrosis. Serum creatinine (sCr) and blood urea nitrogen (BUN) elevations suggestive of mild renal dysfunction were first observed on days 7 to 8. Gentamicin-induced increased urinary kidney injury molecule-1 (KIM-1) mRNA was observed on day 6 preceding detectable elevations of sCr and/or BUN. Increased urinary KIM-1 mRNA correlated with multifocal KIM-1 immunostaining in the corticomedullary tubular epithelial cells. Microarray analysis revealed changes in additional mRNA expression products detected in urine and/or kidney that should be further investigated for use as potential biomarkers for acute gentamicin related nephrotoxicity in dogs. Conclusion: These findings suggested the utility of non-invasive urinary genomic parameters for monitoring acute DIKI in dogs.