High Doses Of Ciprofloxacin Research Articles

Bacterial Filaments Induced by Antibiotic Minimal Inhibitory Concentrations in Persister Cells

Background: The ability of minor subpopulations among clonal populations to survive antibiotics is referred to as bacterial persistence. It is believed that persisters come from latent cells, where antibiotic target areas are less active and incapable of being affected. Objective: 112 clinical Escherichia coli isolates were acquired out of diverse medical samples and genetically identified using the uspA gene, which is part of the housekeeping genes. Methods: The examination of persister cells was carried out by subjecting isolates of E. coli in the exponential phase with high dose of ciprofloxacin (20 fold MIC) and calculating the surviving persister cells using CFU (colony forming units) counts. The detection and measurement of bacterial filament production was done using scanning electron and light microscopy. Results: Results showed that the bacterial filament cells kept on lengthen but cease to divide (no septa formation) at sub-minimal inhibitory doses of ciprofloxacin. Persistent isolates were shown to exhibit a wide range of form and size variations, with cells up to 4.5 times longer than usual. Conclusions: The results showed the importance of antibiotic stress on persisted cells that result in the production of filaments as a means of survival and the need to examine these rare phenotypic variations. These occurrences may be the beginning of the spread of bacterial resistance.

Evolution of antimicrobial resistance in E. coli biofilm treated with high doses of ciprofloxacin.

The evolution of antimicrobial resistance (AMR) has mainly been studied in planktonic bacteria exposed to sub-inhibitory antimicrobial (AM) concentrations. However, in a number of infections that are treated with AMs the bacteria are located in biofilms where they tolerate high doses of AM. In the present study, we continuously exposed biofilm residing E. coli at body temperature to high ciprofloxacin (CIP) concentrations increasing from 4 to 130 times the minimal inhibitory concentration (MIC), i.e., from 0.06 to 2.0 mg/L. After 1 week, the biofilms were full of CIP resistant bacteria. The evolutionary trajectory observed was the same as described in the literature for planktonic bacteria, i.e., starting with a single mutation in the target gene gyrA followed by mutations in parC, gyrB, and parE, as well as in genes for regulation of multidrug efflux pump systems and outer membrane porins. Strains with higher numbers of these mutations also displayed higher MIC values. Furthermore, the evolution of CIP resistance was more rapid, and resulted in strains with higher MIC values, when the bacteria were biofilm residing than when they were in a planktonic suspension. These results may indicate that extensive clinical AM treatment of biofilm-residing bacteria may not only fail to eradicate the infection but also pose an increased risk of AMR development.

Study of hepatotoxins influence in vitro on basic biochemical indicators of liver functional state

An antimicrobial drug of the fluoroquinolone group, ciprofloxacin, is widely used in Ukraine. However, some researchers have noted the probable hepatotoxicity of this drug with prolonged use or use of high doses of ciprofloxacin. The aim of this study was to compare the effects of carbon tetrachloride, as a classical model of hepatocyte injury, with the effects of ciprofloxacin.
 The aim of the study was to investigate the biochemical parameters of the liver when simulating toxic damage to hepatocytes with carbon tetrachloride or ciprofloxacin.
 Materials and methods. The study was carried out on isolated rat hepatocytes, in whose culture medium carbon tetrachloride or ciprofloxacin was added. After incubation in the supernatant and cell homogenate, the activities of marker enzymes of cytolysis were determined: ALT, AST, γ-GTP, LF, LDH, DC and MDA.
 Results. The introduction of ciprofloxacin into the culture of hepatocytes at a concentration of LC50 caused changes in biochemical parameters similar to those caused by carbon tetrachloride. Thus, an increase in ALT, AST, γ-GTP, LF, LDH, DC and MDA was observed when CCl4 or ciprofloxacin was added to the culture.
 Conclusion. Incubation of rat hepatocytes with carbon tetrachloride or ciprofloxacin caused an increase in the level of enzymes and lipid peroxidation products. These parameters are indicators of gross changes in cells, which are the result of impaired keto acid formation, impaired redox reactions, impaired glycogen production

Real-time detection of antibiotics cytotoxicity in rabbit periosteal cells using microfluidic devices with comparison to conventional culture assays

BackgroundLocal antibiotic application has been widely used in orthopedic surgery. The dose-related toxicity of antibiotics towards periosteal tissues and resulting effects on osteogenic expression are yet to be studied.MethodsPeriosteal cells harvested from the medial tibia of New Zealand White rabbits were used. A seeding density of 5 × 103 cells/cm2 was determined to be optimal for testing in the pilot study; the cells were cultured in xCELLigence 96-well plates. Microfluidic impedance analyzers were used to monitor cellular proliferation in microfluidic culture systems with exposure to three different concentrations (10 μg/mL, 100 μg/mL, and 1000 μg/mL) of cefazolin, ciprofloxacin, and vancomycin, respectively. The correlation of cell index at day 7 with optical density values from WST-1 assays using conventional cultures was evaluated by calculating the Pearson’s coefficient. RNA analysis was performed to investigate the expression of osteogenic markers in the cultured cells, including core-binding factor alpha 1 (Cbfa1), osteopontin (OPN), and osteopontin promoter (OPNp), relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as the endogenous control.ResultsA significant dose-related inhibition of cell index was found for all the 3 antibiotics, whereas the WST-1 assays showed a significant dose-related inhibition of cellular proliferation only at a high dose of cefazolin (1000 μg/mL) and medium-to-high dose of ciprofloxacin (100 μg/mL and 1000 μg/mL). Pearson’s coefficient analysis indicated a high correlation between the cell index and optical density values of WST-1 assays only for medium and high doses of ciprofloxacin (100 μg/mL and 1000 μg/mL); a moderate correlation was seen for cefazolin, and a low dose of ciprofloxacin (10 μg/mL). RNA analysis confirmed significant dose-related inhibition of cfba1, OPN, and OPNp expression by all three antibiotics.ConclusionWith optimal seeding amounts, rabbit periosteal cells can be dynamically monitored in the xCELLigence microfluidic system. Dose-related inhibition of cellular proliferation and osteogenic expression was found after exposure to cefazolin and ciprofloxacin. By providing real-time detection and exhibiting comparable correlation, microfluidic impedance-based analyzer is a feasible alternative to the conventional WST-1 assays.

Evaluation of the electron transfer flavoprotein as an antibacterial target in Burkholderia cenocepacia.

There are hundreds of essential genes in multidrug-resistant bacterial genomes, but only a few of their products are exploited as antibacterial targets. An example is the electron transfer flavoprotein (ETF), which is required for growth and viability in Burkholderia cenocepacia. Here, we evaluated ETF as an antibiotic target for Burkholderia cepacia complex (Bcc). Depletion of the bacterial ETF during infection of Caenorhabditis elegans significantly extended survival of the nematodes, proving that ETF is essential for survival of B. cenocepacia in this host model. In spite of the arrest in respiration in ETF mutants, the inhibition of etf expression did not increase the formation of persister cells, when treated with high doses of ciprofloxacin or meropenem. To test if etf translation could be inhibited by RNA interference, antisense oligonucleotides that target the etfBA operon were synthesized. One antisense oligonucleotide was effective in inhibiting etfB translation in vitro but not in vivo, highlighting the challenge of reduced membrane permeability for the design of drugs against B. cenocepacia. This work contributes to the validation of ETF of B. cenocepacia as a target for antibacterial therapy and demonstrates the utility of a C. elegans liquid killing assay to validate gene essentiality in an in vivo infection model.

Pefloxacin as a Surrogate Marker for Fluoroquinolone Susceptibility for Salmonella typhi: Problems and Prospects.

Pefloxacin as a Surrogate Marker for Fluoroquinolone Susceptibility for Salmonella typhi: Problems and Prospects.

Comparative mutant prevention concentration and mechanism of resistance to veterinary fluoroquinolones in Staphylococcus pseudintermedius

The problem of antibacterial drug resistance is increasing worldwide, in part due to the therapeutic concentrations currently used based on the minimal inhibitory concentration (MIC) as a measure of potency are often the very concentrations required to selectively enrich the resistant mutant portion of the population. A mutant prevention concentration (MPC)-based dosing strategy is suggested to improve the therapeutic outcome based on the MIC. Our aim was to investigate the MPC and mechanism of resistance to various fluoroquinolones using recent Staphylococcus pseudintermedius isolates from canine pyoderma. The broth microdilution method for MIC and a series of agar plates containing different concentrations of fluoroquinolones were inoculated with ∼10(10) colony-forming units of the bacterial culture for MPC were used. PCR was used to identify mutation in the resistant isolates. The rank order of potency based on MIC and MPC was ciprofloxacin = enrofloxacin ≥ marbofloxacin > difloxacin ≥ orbifloxacin. Integrating our data with reported pharmacokinetic data at the recommended dose ranges revealed that only high doses of ciprofloxacin, enrofloxacin and marbofloxacin could achieve a maximal plasma concentration (C(max)) greater than the MPC of 90% of isolates (C(max)/MPC(90)). The overall rank of potency against S. pseudintermedius, based on C(max)/MIC, C(max)/MPC, the area under concentration-time curve (AUC)/MIC and AUC/MPC values, was in decreasing order: enrofloxacin > ciprofloxacin ≥ marbofloxacin ≥ orbifloxacin = difloxacin. Sequencing of the quinolone resistant determining region of gyrA, gyrB, grlA and grlB of resistant strains showed a base-pair substitution in both gyrA and gyrB that resulted in Ser-84 to Leu and Ser-80 to Arg amino acid changes, respectively. High doses of ciprofloxacin, enrofloxacin and marbofloxacin could minimize the selection of resistant mutants, whereas the possibility of selecting mutants with the conventional doses of difloxacin and orbifloxacin, and low clinical doses of all fluoroquinolones, seems high.

Effect of Chloroquine on the Bioavailability of Ciprofloxacin in Humans

Chloroquine, a front-line drug in the treatment of malaria, has developed widespread resistance, especially to the Plasmodium falciparum strains. Ciprofloxacin is a second-generation quinolone used as a broad-spectrum fluoroquinolone antibacterial agent. The possibility of using ciprofloxacin as an antimalarial, especially in chloroquine-resistant strains, is very promising. They concluded from in vitro studies however that the anti-malarial effect occur at high dose level of ciprofloxacin to achieve the required serum concentrations. Studies have shown that there is little interstrain variability in the in vitro susceptibility of P. falciparum to fluoroquinolones. There is also no cross-resistance between them. Another study stated that 50% inhibition of parasite growth in vitro required 6.6 microg/mL after a high dose of ciprofloxacin was used. They thus concluded that ciprofloxacin should not be used alone. There is need for in vivo studies to ascertain the achievable serum concentration of ciprofloxacin when given alone and when given in combination with chloroquine. The serum concentration of ciprofloxacin was studied when ciprofloxacin was given alone and in combination with chloroquine in humans. Five healthy male volunteers aged (19-31) years who were not taking any of the prescribed medications and had no sensitivity to either ciprofloxacin or chloroquine, each received 500 mg ciprofloxacin orally with 250 mL of water, and after a 2-week wash-out period, 500 mg ciprofloxacin plus 600 mg of chloroquine was administered orally with 250 mL of water after informed consent. A blood sample (2.5 mL) was collected just before taking the drug at 8:00 AM representing 0 hours and continued afterward at 1, 2, 4, 8, 12, and 24 hours the following day. Serum samples were stored at -20 degrees C until analyzed. The minimal inhibitory concentrations (MIC) by diffusion through agar technique was used for the assay of serum ciprofloxacin. The following bioavailability parameters: Cmax, tmax, and AUC 0-24, AUC 0-infinity were calculated. The peak serum concentration Cmax of ciprofloxacin was 3.42 +/- 0.32 microg/mL, which dropped to 2.8 +/- 0.18 microg/mL when chloroquine was taken together with ciprofloxacin. These values were less than the in vitro 12.5 microg/mL concentrations required to inhibit P. falciparum. Though the effect of parasitemia was not ascertained, the in vivo use of ciprofloxacin alone or in combination is doubtful because increasing the dose that will reach the in vitro level will lead to toxicity in vivo.

Impact of ciprofloxacin in the human-flora-associated (HFA) rat model: Comparison with the HFA mouse model

The ecological impact of different doses of ciprofloxacin was investigated in an experimental germ-free rat model into which human fecal flora was inoculated. Animals received oral doses (gavage) of 0, 0.25, 2.5, and 25 mg/kg body weight (bw) of ciprofloxacin once daily for 5 weeks. All doses of ciprofloxacin significantly reduced aerobic populations. Elimination of Enterobacteriaceae and reduction of bifodibacteria were noticed in the group treated with 25 mg/kg of the antibiotic. The rest of the intestinal flora was not affected. These effects were reversible after the treatment ended. The percentage of resistant enterococci increased in rats treated with 2.5 and 25 mg/kg; however, this increase was not statistically significant. There was a significant ( P < 0.05) emergence of ciprofloxacin-resistant Bacteroides fragilis group with 25 mg/kg bw, which is equivalent to a human therapeutic dosage of the antibiotic. The MIC values and the percentage of resistance remained elevated 2 weeks after the end of treatment in this anaerobic population. Although sub-populations of enterococci and Enterobacteriaceae showed decreased susceptibility after ciprofloxacin administration, resistance was not evident. The ability of an exogenous strain of Salmonella to colonize the intestine of animals treated with 25 mg/kg of ciprofloxacin confirmed that the drug disrupted the colonization barrier effect of the indigenous flora at the high dose level tested. No changes in the metabolic parameters occurred during the antibiotic treatment. The results obtained in the HFA rat model were similar to those obtained in our previous study using the HFA mice model where ciprofloxacin at 0.125, 1.25, and 12.5 mg/kg bw induced a decrease of enterococci and Enterobacteriaceae populations. The high dose of ciprofloxacin also induced a decrease in bifidobacteria counts, an increase in levels of resistant B. fragilis group and a significant ( P < 0.05) disruption of the colonization resistance of the barrier flora in HFA mice.

Treatment of encrusted cystitis caused by Corynebacterium group D2 with norfloxacin, ciprofloxacin, and teicoplanin in an experimental model in rats

Oral doses of norfloxacin (80 mg/kg of body weight per day) and ciprofloxacin (25 and 80 mg/kg/day) and intramuscular doses of teicoplanin (5 mg/kg/day), all administered once a day for 10 days, were evaluated as a means of preventing encrusted cystitis caused by Corynebacterium group D2. Zinc disks dipped into a 24-h broth culture of these microorganisms were inserted into the bladders of female Wistar rats, and treatment was started 14 days after bacterial challenge. The appearance of encrusted cystitis was directly related to a documented urinary tract infection by these coryneforms (71.7 and 0% for rats with positive and negative urine cultures, respectively). All rats that died between days 18 to 43 after bacterial challenge presented very severe encrusted cystitis, which was prevented by teicoplanin and high doses of ciprofloxacin. Rats surviving up to day 44 after bacterial challenge were sacrificed; they presented a lower incidence of encrusted cystitis which was also less severe, with teicoplanin and a high dose of ciprofloxacin being more active in reducing the rate of positive cultures (78.8 and 65.7% reduction, respectively). All antibiotics and doses used were active in vivo at preventing encrusted cystitis by Corynebacterium group D2, but the best therapeutic effect was obtained with teicoplanin.

Effect of ciprofloxacin on stationary bacteria studied in vivo in a murine granuloma pouch model infected with Escherichia coli.

A granuloma pouch model in mice was used to investigate the effect of ciprofloxacin in vivo on cells of Escherichia coli (Neumann) under stationary growth conditions. The animals were treated up to three times intraperitoneally with 2.5, 10 or 40 mg/kg ciprofloxacin 24 h after infection. The numbers of viable bacteria in the pouch exudate were determined over a period of 24 h. A rapid decline of more than 1 logarithmic unit of the number of colony forming units was observed after 2-4 h with all treatment schedules. The effect on stationary cells was more pronounced with the high dose of ciprofloxacin and also dependent on the frequency of treatment. Ciprofloxacin penetrated well into the pouch exudate and reached concentrations of 2.08 +/- 0.16 microgram/ml and 0.1 +/- 0.05 microgram/ml 2 h after treatment with 40 and 2.5 mg/kg, respectively. The results of this study demonstrate that ciprofloxacin is effective in the treatment of a local inflammatory abscess in mice harbouring a stationary population of E. coli.