Doses Of Chloramphenicol Research Articles

Pulmonary disposition and pharmacokinetics of a single oral dose of chloramphenicol in healthy fasted adult horses

Abstract Objective To describe and compare the pulmonary and plasma pharmacokinetics of different oral formulations of chloramphenicol administered as a single dose to healthy adult horses. Methods A single dose of chloramphenicol was administered to 6 healthy, university-owned fasted adult horses IV (25 mg/kg), orally as commercial tablets (50 mg/kg), or orally or intragastrically as compounded suspension (50 mg/kg), according to a randomized crossover protocol. Plasma was collected 5, 10, 15, 20, and 30 minutes and 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours after drug administration. Bronchoalveolar lavage (BAL) fluid was collected after 1, 4, and 8 hours and processed to obtain pulmonary epithelial lining fluid (PELF) and the BAL cell pellet (BALc). Chloramphenicol concentrations were determined by means of liquid chromatography–tandem mass spectrometry in plasma, PELF, and BALc. Data were used for plasma noncompartmental analysis and calculation of apparent PELF and BALc concentrations. Results Chloramphenicol concentrations were higher in the PELF than in plasma, irrespective of formulation and administration route (IV, orally, or intragastrically). Compounded suspension administered intragastrically yielded higher maximum concentration and drug exposure than administered orally, with a relative bioavailability of 79%. After oral administration, no significant differences were found between compounded suspension and commercial tablets. Conclusions Oral administration of chloramphenicol achieved pulmonary concentrations ≥ 2 and 4 µg/mL for at least 4 hours (50% to 75% of a 6- to 8-hour dosing interval) in 4 out of 5 treated horses. Clinical Relevance Pulmonary pharmacokinetics can be used by practitioners to judiciously select an antimicrobial for the treatment of complex equine pneumonia cases.

Cell death and DNA damage via ROS mechanisms after applied antibiotics and antioxidants doses in prostate hyperplasia primary cell cultures.

Tumor heterogeneity results in aggressive cancer phenotypes with acquired resistance. However, combining chemical treatment with adjuvant therapies that cause cellular structure and function perturbations may diminish the ability of cancer cells to resist at chemical treatment and lead to a less aggressive cancer phenotype. Applied treatments on prostate hyperplasia primary cell cultures exerted their antitumor activities through mechanisms including cell cycle blockage, oxidative stress, and cell death induction by flow cytometry methods. A 5.37 mM Chloramphenicol dose acts on prostate hyperplasia cells by increasing the pro-oxidant status, inducing apoptosis, autophagy, and DNA damage, but without ROS changes. Adding 6.30 mM vitamin C or 622 µM vitamin E as a supplement to 859.33 µM Chloramphenicol dose in prostate hyperplasia cells determines a significant increase of ROS level for a part of cells. However, other cells remain refractory to initial ROS, with significant changes in apoptosis, autophagy, and cell cycle arrest in G0/G1 or G2/M. When the dose of Chloramphenicol was increased to 5.37 mM for 6.30 mM of vitamin C, prostate hyperplasia cells reacted by ROS level drastically decreased, cell cycle arrest in G2/M, active apoptosis, and autophagy. The pro-oxidant action of 1.51 mM Erythromycin dose in prostate hyperplasia cell cultures induces changes in the apoptosis mechanisms and cell cycle arrest in G0/G1. Addition of 6.30 mM vitamin C to 1.51 mM Erythromycin dose in hyperplasia cell cultures, the pro-oxidant status determines diminished caspase 3/7 mechanism activation, but ROS level presents similar changes as Chloramphenicol dose and cell cycle arrest in G2/M. Flow cytometric analysis of cell death, oxidative stress, and cell cycle are recommended as laboratory techniques in therapeutic and diagnostic fields.

Potential for extending the chloramphenicol dosing interval for canine urinary tract infections.

Canine urinary excretion of chloramphenicol was evaluated to optimize a dosing protocol for treating urinary tract infections. Seven healthy male intact purpose-bred Beagles and six healthy client-owned dogs of various breeds each received a single oral 50 mg/kg dose of chloramphenicol. Urine was collected at baseline, and 6, 8, 12, and 24 h after chloramphenicol. Chloramphenicol urine concentrations were measured and compared to the epidemiological cutoff value for E. coli (16 mcg/mL). At 8 h, mean chloramphenicol concentration from all dogs was 266.9 mcg/mL (90% CI 136.2-397.7 mcg/mL) but was lower in Beagles than client-owned dogs. At 12 h, mean chloramphenicol concentration from all dogs was 111.0 mcg/mL (90% CI 36.9-185.0 mcg/mL) and was lower in Beagles (10.6 mcg/mL, 90% CI 1.4-19.8 mcg/mL) than client-owned dogs (228.0 mcg/mL, 90% CI 103.0-353.1 mcg/mL). Urine half-life was similar for all dogs (1.8-3.8 h). This justifies dosing chloramphenicol 50 mg/kg PO q 8 h. All client-owned dogs additionally maintained concentrations well above 16 mcg/mL, for 12 h, suggesting that q 12-h dosing might be appropriate for non-Beagle dogs with susceptible lower urinary tract infections. A clinical trial in dogs with urinary tract infections is needed as well as further investigation into potential breed differences.

Enhancing the Efficacy of Chloramphenicol Therapy for Escherichia coli by Targeting the Secondary Resistome.

The increasing prevalence of antimicrobial resistance and the limited availability of new antimicrobial agents have created an urgent need for new approaches to combat these issues. One such approach involves reevaluating the use of old antibiotics to ensure their appropriate usage and maximize their effectiveness, as older antibiotics could help alleviate the burden on newer agents. An example of such an antibiotic is chloramphenicol (CHL), which is rarely used due to its hematological toxicity. In the current study, we employed a previously published transposon mutant library in MG1655/pTF2::blaCTX-M-1, containing over 315,000 unique transposon insertions, to identify the genetic factors that play an important role during growth in the presence of CHL. The list of conditionally essential genes, collectively referred to as the secondary resistome (SR), included 67 genes. To validate our findings, we conducted gene knockout experiments on six genes: arcA, hfq, acrZ, cls, mdfA, and nlpI. Deleting these genes resulted in increased susceptibility to CHL as demonstrated by MIC estimations and growth experiments, suggesting that targeting the products encoded from these genes may reduce the dose of CHL needed for treatment and hence reduce the toxicity associated with CHL treatment. Thus, the gene products are indicated as targets for antibiotic adjuvants to favor the use of CHL in modern medicine.

Effect of sublethal dose of chloramphenicol on biofilm formation and virulence in Vibrio parahaemolyticus.

Vibrio parahaemolyticus isolates are generally very sensitive to chloramphenicol. However, it is usually necessary to transfer a plasmid carrying a chloramphenicol resistance gene into V. parahaemolyticus to investigate the function of a specific gene, and the effects of chloramphenicol on bacterial physiology have not been investigated. In this work, the effects of sublethal dose of chloramphenicol on V. parahaemolyticus were investigated by combined utilization of various phenotypic assays and RNA sequencing (RNA-seq). The results showed that the growth rate, biofilm formation capcity, c-di-GMP synthesis, motility, cytoxicity and adherence activity of V. parahaemolyticus were remarkably downregulated by the sublethal dose of chloramphenicol. The RNA-seq data revealed that the expression levels of 650 genes were significantly differentially expressed in the response to chloramphenicol stress, including antibiotic resistance genes, major virulence genes, biofilm-associated genes and putative regulatory genes. Majority of genes involved in the synthesis of polar flagellum, exopolysaccharide (EPS), mannose-sensitive haemagglutinin type IV pilus (MSHA), type III secretion systems (T3SS1 and T3SS2) and type VI secretion system 2 (T6SS2) were downregulated by the sublethal dose of chloramphenicol. Five putative c-di-GMP metabolism genes were significantly differentially expressed, which may be the reason for the decrease in intracellular c-di-GMP levels in the response of chloramphenicol stress. In addition, 23 genes encoding putative regulators were also significantly differentially expressed, suggesting that these regulators may be involved in the resistance of V. parahaemolyticus to chloramphenicol stress. This work helps us to understand how chloramphenicol effect on the physiology of V. parahaemolyticus.

The new ophthalmic formulation for infection control by combining collagen/gelatin/alginate biomaterial with liposomal chloramphenicol

Eye drops are a conventional method of drug delivery to the eye, accounting for 90% of currently accessible ophthalmic formulations. The major problem with eye drop treatments is rapid pre-corneal drug loss. Furthermore, the need for frequent administration of eye drops can profoundly affect the quality of life of ophthalmological patients. In the current study, we developed a liposomal nanoparticle encapsulated with chloramphenicol mixed with biodegradable materials against ophthalmological disease. We first established a protocol for chloramphenicol (CAP) loaded into liposomal nanoparticle (LipoCAP). We also established the collagen/gelatin/sodium alginate (CGA) as the component of biodegradable polymers and calibrated the novel drug-releasing formulation. Finally, we combined LipoCAP with CGA to generate an 8-h degradable ophthalmic chloramphenicol gel, CGA-LipoCAP-8. CGA-LipoCAP-8 reached the effective working concentration in 75 min and prolonged the drug-releasing time for at least 12 h. In addition, CGA-LipoCAP-8 could stably and continuously inhibit E. coli proliferation. The inhibiting phenomenon was more pronounced over time. Furthermore, there were no significant toxicities observed when CGA-LipoCAP-8 co-cultured with ocular epithelial cells. In conclusion, CGA-LipoCAP-8 achieved effective CAP dose concentrations in a short time and sustained CAP release for a prolonged period. Our results provide an innovative concept in relation to novel drug-release formulations, with safety and efficiency supporting use in future treatments for ophthalmological diseases.

The Effects of Prolonged Chloramphnicol Administration on Heamatological Parameters and Histophatology of Liver, Kidney and Spleen in Broiler Chicken

Chloramphenicol a broad spectrum antibiotic was tested on broiler birds to evaluate the effect of its prolonged administration on heamatological parameters, identification of histopathological changes on organs (Liver, Spleen and Kidneys) and to determine if prolonged effect has effects on weight gain and mortality rate.
 One hundred and twenty day old chicks from Kamadex Ibadan were used for the experiment. The birds were assign to two (2) treatments and control group each replicated in a Complete Randomized Design (CRD), birds in treatment one (T1) were administered normal dose of Chloramphenicol (250 mg/Kg), while treatment two (T2) were served with triple dose in medicated water served ad-lib for seven weeks, while the control (T3) were served with un-medicated water ad-lib. Samples (blood, liver, kidney and spleen) were collected and analyzed after 8 weeks of the experiment.
 Birds showed significant variations in heamatological values across treatments. Lymphocysts count: treatment two (T2) was higher than the treatment one (T1) whereas that of (T3) was found to be less, compared to those of T1 and T2. Heterophils: T3 was higher than the T1 while that of T2 was less as compared to T3 and T1. Basophil: T1 was higher than T3 while that of T2 was less. A lower value was observed in weight gain with birds on T2 as compared to T1 and T3. The liver of birds on T1 and T2 were significantly larger than those on T3. High mortality was recorded in birds on T2 compared to those in T3 and T2.
 The histopathological pictures of the liver, kidney and the Spleen depict a varying degree of necrosis and hemorrhagic foci on all the organs, the changes were much severe on T2 as compared to those of T1 and T3.

Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

To the authors’ knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached. Seven healthy adult horses were administered 50 mg/kg chloramphenicol base tablets PO q6 h for 4 days. Blood was collected via venipuncture daily at 4 and 6 h after administration for the first 15 doses. After the 16th dose, an IV catheter was aseptically placed in the right jugular vein and blood was collected at regular intervals for pharmacokinetic analysis.Maximum chloramphenicol concentration was variable between horses (2.1–42.7 μg/mL). The highest average chloramphenicol concentration was just below the susceptibility breakpoint at 7.7 ug/mL while the lowest was well below the breakpoint at 1.5 ug/mL. On average, the time above 8.0 μg/mL was 75 min, considerably less than the recommended 50% of the dosing interval. When chloramphenicol is administered at a dose of 50 mg/kg PO q6 h in horses, the highest reliably achievable steady state concentration for at least half of the dosing interval is 2.0 μg/mL. The established susceptibility breakpoint of 8.0 ug/mL is not achievable in adult horses, and should be re-evaluated.

Effect of Chloramphenicol on Rabbit Doe Fertility and Prenatal Development

Chloramphenicol (CP) is a synthetic antibiotic with large spectrum, mostly used in human and veterinary medicine to fight against diverse infections. In the present study the effects of this antibiotic on some does reproductive parameters were evaluated on 24 nulliparous, sexually mature female (6 months). The animals were divided into 4 groups of 6 does each, comparable in terms of body weight. To each group was randomly attributed by gavage 25, 50 and 75mg of CP/kg of body weight 30 days before mating (6 females for 1 male) and during the whole gestation period. After sacrifice of the does on the 28th day post-coitum, the organs (ovaries, liver, and kidneys) and fetus were collected and were examined to detect eventual anomalies. The main results showed a non-significant increase (P>0.05) of the relative weight of the liver and kidneys and a non-significant decrease (P>0.05) of that of the ovaries with increase in the dose of CP. No abortions were registered no matter the dose of CP. Gestation index, the rate of fetal mortality and of fetal viability were not significantly affected by the dose of CP used. A decreasing (P<0.05) dependent dose of the average litter size, the average litter weight, the placenta and the gravid uterus, the number of placenta and the implantation sites were registered. However, a non-significant reduction (P>0.05) of the average weight of the fetus and their body measurement, the number of corpus luteum and the sex-ratio (M/F) were registered from treated animals in relation to the control animals. A dose-dependent increase (P<0.05) of number of pre and post-implantation resorptions were noted. The only anomaly registered was the insufficient fusion of the cranial bones at the dose 50 and 75mg/kg of CP. A significant decrease (P<0.05) of the level of proteins in the serum and ovaries were noted in animals treated in relation to those of the control group. It was concluded that CP administered at doses of 25, 50 and 75 mg/kg bw to pre and post-coital rabbit does, negatively affects fertility but has no significant teratogenic effects. Its use should therefore be limited or prohibited in husbandry.

Histological Changes in Liver and Kidney of Clarias gariepinus (Burchell, 1822) Juvenile Exposed to Sub-lethal Doses of Chloramphenicol (CAP)

Histological Changes in Liver and Kidney of Clarias gariepinus (Burchell, 1822) Juvenile Exposed to Sub-lethal Doses of Chloramphenicol (CAP)

Evaluation of days-dependent chloramphenicol dosage on rat liver microsomal lipid peroxidation and catalase activity

Drugs and chemical agents can alter the cellular functions associated with the oxidative metabolism, thereby stimulating ROS production. The objective of the this study was the in vivo study of the inhibitory effect of chloramphenicol on hepatic microsomal enzyme system and the effect on lipid peroxidation using the thiobarbituric acid (TBA) reactive as index of peroxidation damage was investigated. The rats were randomly divided into 3 groups; group 1 serves as the control receiving saline water, group 2 receive chloramphenicol at a dose of 28.6 mg/kg body weight/day for 5 days and group 3 for 7 days. Liver protein content, lipid hydroperoxides and catalase activity were all determined. TBARS concentration increased statistically significantly with time of exposure. After 5 days of treatment, the level of TBARS increased by 103.56% with exogenous oxidant and by 141.54% for without oxidant, as compared to the respective control. On day 7, TBARS level in the liver was approximately 90.75% higher than in the control group with oxidant and 117.03% higher than the control without oxidant. The antibiotic elicited significant increase in rat liver lipid peroxidation compared to control. There were decreases in microsomal protein content of the liver in the drug-treated rats when compared with the control rats. It also showed that chloramphenicol treatment affects cytosolic catalase activities. It decreases catalase levels by 15.75% in 5 days dosage treatment and 17.81% in 7 days dosage treatment respectively. There were significance difference (P<0.05) in the treated and control irrespective of the days of dosage. The catalase level in hepatocyte in 5 days and 7 days group was significance at p<0.01. In conclusion, it was evident that treatment of rats for 5 days and 7 days with the therapeutic doses of Chloramphenicol altered antioxidant system and the intensity of effects was concentration/dosage days dependent, it resulted in membrane lipid peroxidation, protein damage, and inhibition of microsomal catalase due to increased generation of free radicals, reactive oxygen species and reactive nitrogen speciesKeywords: Chloramphenicol, rat liver, lipid peroxidation, catalase activity, antioxidant

Management of Typhoid Fever and Bacterial Meningitis by Chloramphenicol in Infants and Children

Chloramphenicol inhibits protein synthesis in bacteria and is usually bacteriostatic but is bactericidal against Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitis. Chloramphenicol penetrates all body tissues well. The cerebrospinal fluid concentration averages 60% of the serum level, while brain levels are 9 times higher because of high lipid solubility of this drug. Chloramphenicol acts primarily by binding reversibly to the 50S ribosomal subunit. This antibiotic is the drug of choice for the treatment of typhoid and paratyphoid fevers and bacterial meningitis. Chloramphenicol possesses a broad-spectrum of antimicrobial activity. Strains are considered sensitive if they are inhibited by chloramphenicol concentrations of ≤ 8 µg/ml. Neisseria gonorrhea, Brucella species, Bordetella pertussis, gram-positive cocci, Clostridium species, and gram-negative rods including Bacillus fragilis are inhibited by chloramphenicol. Most anaerobic bacteria including Mycoplasma, Chlamydia, Rickettsiae, Vibrio cholera, Escherichia coli and Klebsiella pneumoniae are inhibited by this antibiotic. The doses of chloramphenicol are 40.5 mg/kg/day for neonates and 75.5 mg/kg/day for older children. The therapeutic concentrations of chloramphenicol are 10-25 µg/ml. Peak therapeutic concentrations are obtained in 60% and therapeutic trough concentrations are found in 42% of children. Children affected by typhoid fever are cu red by chloramphenicol and the sensitivity to this antibiotic is 100%. Acute bacterial meningitis is the most dangerous infections disease in children. The causative organisms are gram-positive and gram-negative bacteria, and chloramphenicol is effective in killing these microorganisms. The aim of this study is to review the management of typhoid fever and bacterial meningitis in infants and children by chloramphenicol.

Synergistic effect of haloduracin and chloramphenicol against clinically important Gram-positive bacteria

The emergence of drug-resistant pathogens has triggered the search for more efficient antimicrobial agents and formulations for treatment of infections. In recent years, combination therapy has become one of the effective clinical practices in treating infections. The present study deals with the effect of haloduracin, a lantibiotic bateriocin and chloramphenicol against clinically important bacteria. The combined use of haloduracin and chloramphenicol resulted in remarkable synergy against a spectrum of microorganisms including strains of Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis and different groups of Streptococcus. The synergy allowed using these antimicrobial agents at substantially reduced concentrations without compromising their efficiency. Use of lower doses of chloramphenicol can avoid the severity of its side effects. In addition to minimizing undesirable side effects of some drugs, this approach brings the possibility of using antibiotics that are no longer effective due to drug resistance. Furthermore, the observed synergy between haloduracin and chloramphenicol opens a new window of using bacteriocins and antibiotics in combination therapy of infections.

Eco-friendly gelatin-based electrospun fibers to control the release of chloramphenicol

Chloramphenicol, antibiotic drug is widely used in the developing countries, may cause bone marrow suppression during its topical treatment and affecting red blood cells. Because the accumulation of high dose of chloramphenicol is necessary for this side effect, controlling its release rate is a possible approach to reduce the risk of its topical application. In the present work, chloramphenicol was encapsulated into gelatin electrospun fibers that cross-linked with non-toxic crosslinker. β-cyclodextrin, cyclic oligosaccharides of 7 membered-sugar ring, was selectively oxidized to cleave the carboncarbon bond in positions C-2 and C-3 of the glucose units to yield two aldehyde groups and end up with poly aldehyde β- cyclodextrin (PA-β-CD). Matrix was designed to control chloramphenicol release rate from nontoxic and biodegradable electrospun mat for topical applications. Bead-free electrospun fibers were produced at the concentration of 24 % w/v gelatin solution at 15 kV with gap distance of 17 cm with a flow rate of 2 ml/hr. Electrospun fibers were produced in the nanoscale (450-150 nm). 6 % of chloramphenicol was chosen to carry out the cross-linked matrices by using PA-β-CD. The encapsulation efficacy was investigated by UV-isible spectroscopy and the antimicrobial activities were demonstrated against Staphylococcus aureus (gram positive) and Pseudomonas aeruginosa (gram negative bacteria) and Candida albicans. The results showed that the samples have a strong inhibitory activity against all pathogenic microorganisms used.

Florfenicol induces more severe hemotoxicity and immunotoxicity than equal doses of chloramphenicol and thiamphenicol in Kunming mice

Amphenicols are effective, broad-spectrum antibiotics that function by inhibiting the peptidyl transferase activity of bacteria, while the drugs can also inhibit mitochondrial protein synthesis in eukaryotes through the same mechanism, which leads to multi-organ toxicity. Some side effects of each drug have been studied, while differences in the severity of the hemotoxicities and immunotoxicities of amphenicols have not been reported. Thus, it is important to identify, evaluate, and compare the potential hemotoxicities and immunotoxicities to guide their proper use in humans and animals, which will guarantee food safety and animal welfare. Ovalbumin-immunized Kunming mice were gavaged daily with amphenicols for seven days. Blood samples were collected for hematology analysis, and measuring anti-ovalbumin antibody levels and serum intereukin-2 concentrations. The bone marrow, spleen and thymus were collected for histopathology and apoptosis analyzes. Bone marrow nucleated cells (BMNCs) and splenocytes were harvested to determine their cell cycle stages and to analyze lymphocyte proliferation. The results demonstrated that amphenicols, especially florfenicol (FLO), induced cell cycle arrest and apoptosis of hematopoietic cells, and it changed the bone marrow hematopoietic microenvironment by decreasing the number of peripheral blood cells. Moreover, amphenicols, especially FLO, induced hypoplasia and atrophy of the spleen and thymus, induced cell cycle arrest, as well as splenocyte apoptosis, and decreased the proliferation and viability of lymphocytes and the humoral and cellular immunity of the treated mice. These results suggest that amphenicols induce hemotoxicity and immunotoxicity to some extent, and that FLO induces more severe toxicity than equal doses of chloramphenicol (CAP) and thiamphenicol (TAP).

Distribution of chloramphenicol to tissues, plasma and urine in pigs after oral intake of low doses

ABSTRACTToxic effects of chloramphenicol in humans caused the ban for its use in food-producing animals in the EU. A minimum required performance level (MRPL) was specified for chloramphenicol at 0.3 μg kg–1 for various matrices, including urine. In 2012, residues of chloramphenicol were found in pig urine and muscle without signs of illegal use. Regarding its natural occurrence in straw, it was hypothesised that this might be the source, straw being compulsory for use as bedding material for pigs in Sweden. Therefore, we investigated if low daily doses of chloramphenicol (4, 40 and 400 μg/pig) given orally during 14 days could result in residues in pig tissues and urine. A dose-related increase of residues was found in muscle, plasma, kidney and urine (showing the highest levels), but no chloramphenicol was found in the liver. At the lowest dose, residues were below the MRPL in all tissues except in the urine. However, in the middle dose, residues were above the MRPL in all tissues except muscle, and at the highest dose in all matrices. This study proves that exposure of pigs to chloramphenicol in doses occurring naturally in straw could result in residues above the MRPL in plasma, kidney and especially urine.

Regulatory science needs for neonates: a call for neonatal community collaboration and innovation.

Neonates have long been a vulnerable population to unstudied therapies, starting as early as the late nineteenth century with Mrs. Winslow’s Soothing Syrup, a purported remedy for teething that contained alcohol and morphine sulfate, causing numerous infant deaths (1). In 1959, Gray baby syndrome was first reported in infants receiving large doses of chloramphenicol as a broad spectrum antibacterial agent (2), and in 1983, Mulhall et al. (3) noted the altered pharmacokinetics (PK) of chloramphenicol in neonates and young infants resulting in elevated serum levels and some toxic effects.

Effect of phenobarbital on chloramphonicol-induced toxicity in rat liver and small intestine.

The aim of the present study is to determine the effect of Chloramphenicol (CAP) on rat liver and small intestine. Effect of phenobarbital (PB) on CAP toxicity was also investigated. Rats were received CAP at doses of 0, 200, 400 and 600 mg/kg. Another group was pretreated with 80 mg/kg PB 30 min prior to administration of various doses of CAP. The experiment was repeated for seven consecutive days. Blood was collected for determination of serum aspartate aminotransferase (AST) alanine aminotransferase (ALT). The liver and small intestine tissues were processed for light microscopy. CAP induced a dose dependent elevation of AST and ALT and produced injury in the liver and small intestine when compared to control animals. PB markedly decreased AST and ALT levels and protected liver and small intestine against CAP-induced toxicity. Conclusion : This study suggested rat liver and small intestine have potential to bioactivate CAP.

Uncovering toxicological complexity by multi-dimensional screenings in microsegmented flow: modulation of antibiotic interference by nanoparticles

The technique of microsegmented flow was applied for the generation of two- and higher dimensional concentration spaces for the screening of toxic effects of selected substances on the bacterium Escherichia coli at the nanolitre scale. Up to about 5000 distinct experiments with different combinations of effector-concentrations could be realized in a single experimental run. This was done with the help of a computer program controlling the flow rates of effector-containing syringe pumps and resulted in the formation of multi-dimensional concentration spaces in segment sequences. Prior to the application of this technique for toxicological studies on E. coli the accuracy of this method was tested by simulation experiments with up to five dissolved dyes with different spectral properties. Photometric microflow-through measurement of dye distribution inside the concentration spaces allowed the monitoring of microfluid segment compositions. Finally, we used this technique for the investigation of interferences of the antibiotics ampicillin and chloramphenicol towards E. coli cultures and their modulation by silver nanoparticles by measuring bacterial autofluorescence. Each concentration point in this three-dimensional concentration space was represented by 4 or 5 single segments. Thus, a high reliability of the measured dose/response relations was achieved. As a result, a complex response pattern was discovered including synergistic and compensatory effects as well as the modulation of the range of stimulation of bacterial growth by a sublethal dose of chloramphenicol by silver nanoparticles.

Identification of Enterococcus mundtii as a pathogenic agent involved in the “flacherie” disease in Bombyx mori L. larvae reared on artificial diet

Enterococcus mundtii was shown to be directly correlated with flacherie disease of the silkworm larvae reared on artificial diet supplemented with chloramphenicol. Its identification was carried out by means of light and electron microscopy and nucleotide sequencing of 16S gene. The bacterium is capable of rapidly multiplying in the silkworm gut and of invading other body tissues, as demonstrated by deliberate infection of germfree larvae and by subsequent TEM observations. E. mundtii can endure alkaline pH of the silkworm gut and it has been proved to adapt in vitro to commonly applied doses of chloramphenicol, whose use can further contribute to reduce competition by other bacteria in Bombyx mori alimentary canal.The modality of transmission of the infection to the larvae was among the objectives of the present research. Since contamination of the progeny by mother moths can be avoided through routine egg shell disinfection, a trans-ovarian vertical transmission can be ruled out. On the other hand the bacterium was for the first time identified on mulberry leaves, and therefore artificial diet based on leaf powder could be a source of infection. We showed that while microwaved diet could contain live E. mundtii cells, the autoclaved diet is safe in this respect. Being E. mundtii also part of the human-associated microbiota, and since B. mori is totally domestic species, a possible role of man in its epidemiology can be postulated.