Antibacterial activity of gentamicin sulfate in tissue culture

Effects of long-term antibiotic treatment on mice urinary aromatic amino acid profiles

The gut microbiota-host co-metabolites are good indicators for representing the cross-talk between host and gut microbiota in a bi-direct manner. There is increasing evidence that levels of aromatic amino acids (AAAs) are associated with the alteration of intestinal microbial community though the effects of long-term microbial disturbance remain unclear. Here we monitored the gut microbiota composition and host-microbiota co-metabolites AAA profiles of mice after gentamicin and ceftriaxone treatments for nearly 4 months since their weaning to reveal the relationship between host and microbiome in long- term microbial disturbances. The study was performed employing targeted LC-MS measurement of AAA-related metabolites and 16S RNA sequence of mice cecal contents. The results showed obvious decreased gut microbial diversity and decreased Firmicutes/Bacteroidetes ratio in the cecal contents after long-term antibiotics treatment. The accumulated AAA (tyrosine, phenylalanine and tryptophan) and re-distribution of their downstreaming metabolites that produced under the existence of intestinal flora were found in mice treated with antibiotics for 4 months. Our results suggested that the long-term antibiotic treatment significantly changed the composition of the gut microbiota and destroyed the homeostasis in the intestinal metabolism. And the urinary AAA could be an indicator for exploring interactions between host and gut microbiota.

Long-term stability of gentamicin sulfate-ethylenediaminetetraacetic acid disodium salt (EDTA-Na2) solution for catheter locks

A lock solution composed of gentamicin sulfate (5 mg/mL) and ethylenediaminetetraacetic acid disodium salt (EDTA-Na₂, 30 mg/mL) could fully eradicate in vivo bacterial biofilms in totally implantable venous access ports (TIVAP). In this study, fabrication, conditioning and sterilization processes of antimicrobial lock solution (ALS) were detailed and completed by a stability study. Stability of ALS was conducted for 12 months in vial (25 °C ± 2 °C, 60% ± 5% relative humidity (RH), and at 40 °C ± 2 °C, RH 75% ± 5%) and for 24 h and 72 h in TIVAP (40 °C ± 2 °C, RH 75% ± 5%). A stability indicating HPLC assay with UV detection for simultaneous quantification of gentamicin sulfate and EDTA-Na₂ was developed. ALS was assayed by ion-pairing high performance liquid chromatography (HPLC) needing gentamicin derivatization, EDTA-Na₂ metallocomplexation of samples and gradient mobile phase. HPLC methods to separate four gentamicin components and EDTA-Na₂ were validated. Efficiency of sterility procedure and conditioning of ALS was confirmed by bacterial endotoxins and sterility tests. Physicochemical stability of ALS was determined by visual inspection, osmolality, pH, and sub-visible particle counting. Results confirmed that the stability of ALS in vials was maintained for 12 months and 24 h and 72 h in TIVAP.

Gut microbiota composition modifies fecal metabolic profiles in mice

The gut microbiome is known to be extensively involved in human health and disease. In order to reveal the metabolic relationship between host and microbiome, we monitored recovery of the gut microbiota composition and fecal profiles of mice after gentamicin and/or ceftriaxone treatments. This was performed by employing (1)H nuclear magnetic resonance (NMR)-based metabonomics and denaturing gradient gel electrophoresis (DGGE) fingerprint of gut microbiota. The common features of fecal metabolites postantibiotic treatment include decreased levels of short chain fatty acids (SCFAs), amino acids and primary bile acids and increased oligosaccharides, d-pinitol, choline and secondary bile acids (deoxycholic acid). This suggests suppressed bacterial fermentation, protein degradation and enhanced gut microbial modification of bile acids. Barnesiella, Prevotella, and Alistipes levels were shown to decrease as a result of the antibiotic treatment, whereas levels of Bacteroides, Enterococcus and Erysipelotrichaceae incertae sedis, and Mycoplasma increased after gentamicin and ceftriaxone treatment. In addition, there was a strong correlation between fecal profiles and levels of Bacteroides, Barnesiella, Alistipes and Prevotella. The integration of metabonomics and gut microbiota profiling provides important information on the changes of gut microbiota and their impact on fecal profiles during the recovery after antibiotic treatment. The correlation between gut microbiota and fecal metabolites provides important information on the function of bacteria, which in turn could be important in optimizing therapeutic strategies, and developing potential microbiota-based disease preventions and therapeutic interventions.

Effect of Taurine on the antimicrobial efficiency of Gentamicin

CONTEXT

Gentamicin is mainly used in severe infections caused by gram-negatives. However toxicity including nephrotoxicity and ototoxicity is one of the most important complications of its treatment. The production of free radicals seems to be involved in gentamicin toxicity mechanism. Taurine, a major intracellular free β-amino acid, is known to be an endogenous antioxidant. So potentially the co-therapy of taurine and gentamicin would reduce the adverse effects of the antibiotic.

OBJECTIVES

In this study, we wished to know the effect of taurine on the antibiotic capacity of gentamicin.

METHODS

strainsof P. aeruginosa, E. coli, S. aureus and S. epidermidis were used as test organisms. Minimum inhibitory concentrations of gentamicin in the presence and absence of taurine at quantities from 40 to 2 mg/L were determined using macro-dilution method.

RESULTS

MICs were determined in the various concentrations of taurine for bacterial indicators. The MIC values of gentamicin for P. aeruginosa, S. aureus and E. coli remained unchanged in the values of 2.5, 5 and 20 μg/ml respectively in the absence and presences of different concentrations of taurine. The bactericidal activity of gentamicin against S. epidermidis was increased by addition of taurine in the concentrations higher than 6 mg/L.

CONCLUSION

According to our study the antibacterial activity of gentamicin against the indicator microorganisms were not interfere with taurine at selected concentrations. Further in vivo studies are needed to establish if a combination of gentamicin and taurine would have the same effect.

Oxygen dependency of hydrogen sulfide-mediated vasoconstriction in cyclostome aortas

Hydrogen sulfide (H2S) has been proposed to mediate hypoxic vasoconstriction (HVC), however, other studies suggest the vasoconstrictory effect indirectly results from an oxidation product of H2S. Here we examined the relationship between H2S and O2 in isolated hagfish and lamprey vessels that exhibit profound hypoxic vasoconstriction. In myographic studies, H2S (Na2S) dose-dependently constricted dorsal aortas (DA) and efferent branchial arteries (EBA) but did not affect ventral aortas or afferent branchial arteries; effects similar to those produced by hypoxia. Sensitivity of H2S-mediated contraction in hagfish and lamprey DA was enhanced by hypoxia. HVC in hagfish DA was enhanced by the H2S precursor cysteine and inhibited by amino-oxyacetate, an inhibitor of the H2S-synthesizing enzyme,cystathionine β-synthase. HVC was unaffected by propargyl glycine, an inhibitor of cystathionine λ-lyase. Oxygen consumption(ṀO2) of hagfish DA was constant between 15 and 115 mmHg PO2 (1 mmHg=0.133 kPa), decreased when PO2 <15 mmHg, and increased after PO2 exceeded 115 mmHg. 10 μmol l–1 H2S increased and ⩾100μmol l–1 H2S decreased ṀO2. Consistent with the effects on HVC, cysteine increased and amino-oxyacetate decreased ṀO2. These results show that H2S is a monophasic vasoconstrictor of specific cyclostome vessels and because hagfish lack vascular NO, and vascular sensitivity to H2S was enhanced at low PO2, it is unlikely that H2S contractions are mediated by either H2S–NO interaction or an oxidation product of H2S. These experiments also provide additional support for the hypothesis that the metabolism of H2S is involved in oxygen sensing/signal transduction in vertebrate vascular smooth muscle.

Monolayer cultures of perikarya isolated from postnatal rat cerebellum

Viable cerebellar perikarya of mixed cell type obtained from 7--9-day-old rats were maintained in monolayer cutlure for up to 12 days. During this time extensive neurite formation and outgrowth occurred. The large majority of the cells developing in culture were tentatively identified as granule neurons. This identification was based on the large number isolated from the starting tissue, and the cells' general morphological features in culture such as perikaryal and nuclear size, the bipolar nature of neurite extension, and their migratory behaviour.

Effects of some antibiotics on the growth of human diploid skin fibroblasts in cell culture

During serial subcultures 50 micrograms per ml gentamicin and penicillin (100 U per ml)-streptomycin (100 micrograms per ml) depressed cell growth signficantly 2 weeks after the addition of the antibiotics; gentamicin, but not penicillin-streptomycin, stimulated cell growth before it became inhibitory. Removal of the antibiotics resulted in the cell yield returning to normal. The results show that these antibiotics can be harmful to cells even at concentrations thought to be safe.

Computed resolution and relative specific radioactivities of radiolabelled proteins synthesized by isolated gastric mucosal cells

1. By radiolabelling, polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate and fluorography, more than 50 soluble proteins in the molecular-weight range 15000-100000 were shown to continue to be synthesized after cells had been isolated from rat gastric mucosa. 2. Densitometric measurements of stained gels and fluorographic films were processed by computer to resolve individual overlapping Gaussian peaks corresponding to the protein bands. 3. Comparison of resolved peak areas of radioactivity and staining showed certain bands to have characteristically high relative specific radioactivities. 4. The computer programs (in FORTRAN) permit the analysis of a single densitometric trace or the simultaneous comparison of a corresponding pair of densitometric records of stained gels, or of fluorographic films, or a combination. Central processing unit time is used economically. 5. The programs identify the Gaussian components that contribute to the records and estimate their means, standard deviations and enclosed areas. These estimates are improved by a piecewise iterative method that minimizes the errors between the calculated and the experimental data. 6. Relative specific radioactivities are calculated as the normalized ratio of the area of a fluorographic film peak and the area of the corresponding stained gel peak. The computer programs have been deposited as Supplementary Publication SUP 50094 (55 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1978) 169, 5.

Uptake and release of tetracycline by cultured carrot cells

The nature of tetracycline uptake by carrot cell suspension cultures is described. Tetracycline enters the cells by diffusion and the intracellular level of the antibiotic increases with the amount added. Exposure of carrot cells to high levels of tetracycline for a limited time (24 hr) followed by the removal of the drug and the resuspension of the cells in drug-free medium does not affect cell growth and has no inhibitory effect on protein synthesis (14C-leucine incorporation).

Effect of gentamicin on growth of viral, chlamydial, and rickettsial agents in mice and embryonated eggs

Gentamicin, at concentrations up to 500 mug/ml, showed no effect on the replication, yield, or infectivity of seven viruses or on the agents of psittacosis and meningopneumonitis when grown in mice or embryonated eggs. At the 500 mug/ml level, lymphogranuloma venereum cultures had a slight reduction in infectivity. Rickettsia akari demonstrated susceptibility at the 5 mug/ml level, whereas R. rickettsii, R. mooseri, and R. canada grown in embryonated eggs were susceptible in varying degrees to gentamicin at or above the 50 mug/ml concentration.

Clinical evaluation of the addition of gentamicin to commercially prepared mycological media

A simple procedure is presented whereby an antibiotic solution can be added to prepared agar media for conversion to a selective medium to isolate fungi. Gentamicin solution was deposited onto slants of a variety of previously prepared agar media, allowed to diffuse overnight, and then the slants were inoculated with clinical specimens. Control media without gentamicin included a cycloheximide-chloramphenicol medium (CC), Sabouraud dextrose agar (SDA), and brain heart infusion agar (BHI). Of 75 specimens originating from the respiratory tract, the fungi isolated were predominantly yeast; 35, 39, and 43 were positive on CC, SDA, and SDA with gentamicin, respectively, incubated at 25 C. At 37 C, 32, 34, and 41 positive cultures were obtained with the same media, respectively. The same specimens, inoculated onto BHI with and without gentamicin, yielded 23 and 39 positive cultures, respectively. Of 90 specimens that were either urine, cutaneous, or mucocutaneous, the predominant flora again were yeasts, although on nine occasions dermatophytes were isolated. Positive cultures, 32, 34, and 41, were obtained with CC, SDA, and SDA containing gentamicin, respectively. Bacterial contamination was significantly reduced by the gentamicin, especially on BHI incubated at 37 C. None of the specimens was positive for systemically pathogenic fungi, other than species of Candida, Torulopsis, and Aspergillus. The effectiveness of varying concentrations of gentamicin was investigated by comparing growth of recently isolated bacteria. Of the bacterial isolates, 33% grew on CC, 16% grew on SDA containing gentamicin, 50 mug/ml, and 3% grew on SDA with a gentamicin concentration at 100 mug/ml. With BHI, 3% grew in the presence of 50 mug of gentamicin/ml and less than 1% grew at 100 mug of gentamicin/ml.

Gentamicin as a bactericidal antibiotic in tissue culture

The effects of gentamicin on cellular physiology were studied in a total of 9 mammalian cell lines, using the following parameters: cell morphology and viability (cytotoxicity), proliferation, culture medium acidification, lactic acid production, lactate dehydrogenase release, virus susceptibility, and effects on karyotype. With regard to cytotoxicity no gross differences could be found in the sensitivity of the diploid and aneuploid cells investigated, as judged by morphological criteria. However, cells exposed to the antibiotic in the lag-log phase of growth showed damage at lower concentrations (1000 mug/ml) than cells treated in the stationary phase (2000 mug/ml). As regards the influence of gentamicin on cell growth and metabolsim, dose-response relationship were found proving that the antibiotic causes a depression of proliferation, a striking increase in lactate production, an elevated LDH release, and changes in pH behaviour. All these parameters were unaffected by concentrations up to 125 mug/ml. No gross changes in chromosome morphology and number could be detected in huploid cell line after 10 passages with 50 mug/ml gentamicin in lieu of the usual penicillin plus streptomycin combination. The minimal bactericidal concentrations (MBC) were determined in cell-free media and in tissue cultures against 4 species of bacteria. The MBC of gentamicin was generally lower as compared with the penicillin plus streptomycin combination. In some instances MBC was higher in the presence than in the absence of ti-sue culture cells. Comparison of the bactericidal efficiency against 31 strains of 7 species of bacteria of gentamicin (50 mug/ml) and penicillin plus streptomycin (100 units plus 100 mug/ml) in cell cultures proved that gentamicin is superior for control of bacterial growth in tissue culture.

Gentamicin as a selective agent for the isolation of beta haemolytic streptococci

The isolation of beta haemolytic streptococci was compared using Columbia sheep blood agar with and without gentamicin in a final concentration of 5.5 micrograms per ml. The inclusion of gentamicin gave greatly improved results whenever the isolation of this organism in pure culture was complicated by overgrowth with Gram-negative bacilli or staphylococci.

Evaluation of gentamicin for use in virology and tissue culture

Data are presented comparing gentamicin to penicillin and streptomycin (Pen-Strep) in tissue culture medium with respect to a number of parameters associated with virology and tissue culture. Unlike Pen-Strep, gentamicin was stable at pH 2 to 10 for 15 days at 37 C in tissue culture medium, and its activity was unaffected by the presence of serum. Moreover, it was stable to autoclaving. Twenty cell types replicated normally at the suggested concentration of 50 mug/ml, and all cells were unaffected by 20 times this concentration. Evidence for its practical use in virus studies was demonstrated in that (i) it was not viricidal to ribonucleic acid or deoxyribonucleic acid viruses at 40 times the suggested concentration at 37 C, (ii) the size and number of plaques were not affected by 20 times the suggested concentration, (iii) interferon assays and production were unaffected by 20 times the suggested concentrations. Gentamicin may be uniquely useful for shipment of clinical specimens and long-term tissue culture and virus studies.