Víctor Hormazábal

Persistence of antibacterial agents in marine sediments

Abstract The persistence of the antibacterial agents oxytetracycline chloride (OTC), oxolinic acid (OA), flumequine (FLU), sarafloxacin (SAR), florfenicol (FLO), sulfadiazine (SDZ) and trimethoprim (TRM) were compared in marine sediments. Polyethylene boxes were filled with sediment, the antibacterial compounds added and placed on the sea bed at approximately 15 m depth for a period of 180–230 days. Sediment cores were collected by a diver and analyzed for residues of the antibacterials in four depth intervals from 1 to 7 cm. OTC and the quinolones OA, F and SAR were found to be very persistent in the sediment. In the deeper layer of the sediment the initial concentrations of these compounds were present after 180 days, whereas the residues in the top layer of the sediment depurated more rapidly. The depuration of these substances from the sediment is most probably due to leaching and redistribution rather than degradation. The quinolones were found to adsorb to sediment. SDZ and TRM were less persistent than the quinolones; however, the estimated half-life in the deepest layer (6–7 cm) was approximately 90 days for both substances. The concentration of FLO decreased rapidly in the sediment with a calculated half-life of 4.5 days, and a metabolite, florfenicol amine, was identified in the sediment.

Toxin-Producing Ability among Bacillus spp. Outside the Bacillus cereus Group

ABSTRACT A total of 333 Bacillus spp. isolated from foods, water, and food plants were examined for the production of possible enterotoxins and emetic toxins using a cytotoxicity assay on Vero cells, the boar spermatozoa motility assay, and a liquid chromatography-mass spectrometry method. Eight strains produced detectable toxins; six strains were cytotoxic, three strains produced putative emetic toxins (different in size from cereulide), and one strain produced both cytotoxin(s) and putative emetic toxin(s). The toxin-producing strains could be assigned to four different species, B. subtilis, B. mojavensis, B. pumilus, or B. fusiformis, by using a polyphasic approach including biochemical, chemotaxonomic, and DNA-based analyses. Four of the strains produced cytotoxins that were concentrated by ammonium sulfate followed by dialysis, and two strains produced cytotoxins that were not concentrated by such a treatment. Two cultures maintained full cytotoxic activity, two cultures reduced their activity, and two cultures lost their activity after boiling. The two most cytotoxic strains (both B. mojavensis) were tested for toxin production at different temperatures. One of these strains produced cytotoxin at growth temperatures ranging from 25 to 42°C, and no reduction in activity was observed even after 24 h of growth at 42°C. The strains that produced putative emetic toxins were tested for the influence of time and temperature on the toxin production. It was shown that they produced putative emetic toxin faster or just as fast at 30 as at 22°C. None of the cytotoxic strains produced B. cereus-like enterotoxins as tested by PCR or by immunological methods.

Resistance to oxytetracycline, oxolinic acid and furazolidone in bacteria from marine sediments

Abstract Sediments experimentally treated with oxytetracycline (OTC) or oxolinic acid (OXA) were placed on the seabottom for a period of 1 year. At the end of the test period the fraction of bacteria resistant to OTC in sediments to which OTC had been added (SOT) was more than three times higher (16%) than the background level (5%). The same tendency was found for the sediments to which OXA was added (SOX). Cross-resistance towards OTC and OXA was found both in SOT and SOX. A high level of cross-resistance (34%) towards furazolidone was found for SOX, but was not observed for SOT.

Pharmacokinetic study of oxytetracycline in fish. I. Absorption, distribution and accumulation in rainbow trout in freshwater

Abstract The absorption, distribution and elimination of oxytetracycline in plasma, muscle, liver, intestine, mucus, skin and vertebrae in rainbow trout in freshwater were studied after a single dose of 150 mg/kg fish. The absorption of the drug was slow and only about 2.6% of the administered dose was absorbed at the time of maximum absorption. The distribution to all tissues of the fish was good, and a considerable affinity of OTC to tissues was observed. The slow elimination was demonstrated by the long halflife which was 11.6 days from plasma.

Reservoir of quinolone residues in fish

Different tissues from salmon treated with the quinolones oxolinic acid, flumequine, enrofloxacin and sarafloxacin were analysed in search of possible reservoirs of the drugs. Residues of oxolinic acid and flumequine seem to be especially bound to bone, enrofloxacin to skin, and sarafloxacin to both skin and bone. The results showed that residues of these drugs were present in the fish for prolonged periods after the end of treatment.

Antibacterial activity of sphagnum acid and other phenolic compounds found in Sphagnum papillosum against food-borne bacteria.

Aims:  To identify the phenolic compounds in the leaves of Sphagnum papillosum and examine their antibacterial activity at pH appropriate for the undissociated forms.

DETERMINATION OF AMPROLIUM, ETHOPABATE, LASALOCID, MONENSIN, NARASIN, AND SALINOMYCIN IN CHICKEN TISSUES, PLASMA, AND EGG USING LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

A liquid chromatographic-atmospheric pressure ionization ion spray method for the determination of some coccidiostatics in chicken egg, fat, liver, muscle, and plasma is presented. The samples were extracted with acetone-tetrahydrofuran. The water and the organic layer was then separated using a liquid-liquid extraction step and the organic phase was then evaporated to dryness. The dry residue was diluted in hexane and a portion of the organic phase was cleaned-up with a simple step for ethopabate analyses while the rest of the organic phase was purified using a silica solid phase extraction column to analyse lasalocid, monensin, narasin, and salinomycin. The water phase (amprolium analyses) was diluted with water, filtered, and injected into the LC-MS. Three different analytical columns were used. The detection limits were from 1 ng/g to 7 ng/g for chicken tissue and from 4 to 10 ng/mL for plasma.

SIMULTANEOUS DETERMINATION OF THE CYANOTOXINS ANATOXIN A, MICROCYSTIN DESMETHYL-3, LR, RR, AND YR IN FISH MUSCLE USING LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

A liquid chromatographic-atmospheric pressure ionization ion spray method for the determination of anatoxin-a, microcystin desmethyl-3, LR, RR, and YR in fish muscle, is described. A salmon muscle sample was extracted with a mixture of methanol-water and acetone. The organic layer was evaporated and cleaned-up using LMS solid phase extraction columns. The method is simple, specific, and requires only small quantities of chemical reagents. The lower limits of quantification were 15, 2, 10, 1, and 10 ng/g for anatoksin-a, microcystin desmethyl-3, LR, RR, and YR, respectively.

Optimization of Solid Phase Extraction of Oxytetracycline from Fish Tissue and its Determination by HPLC

Abstract The extraction of oxytetracycline from fish tissues by use of solid phase extraction columns has been studied. The best recovery was obtained by using a C8 column and eluting with water/acetone (5% and 10% mixtures). The sensitivity of the method was 5 ng/g for muscle and 10 ng/g for liver. The repeatability of the assay on 10 samples at 1 μg/g and 0.1 μg/g was determined by the standard deviation equal to 4.2% and 6.7%, respectively. The recovery was 89.3% and 94.8%, respectively. The recovery of the internal standard (demeclocycline) was 82.8%.

SIMULTANEOUS DETERMINATION OF CHLORAMPHENICOL AND KETOPROFEN IN MEAT AND MILK AND CHLORAMPHENICOL IN EGG, HONEY, AND URINE USING LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

A liquid chromatographic-atmospheric pressure ionization ion spray method is described for the determination of chloramphenicol and ketoprofen in meat and milk, chloramphenicol in egg, honey, and urine. The samples were extracted with acetonitrile (acetone for urine), the organic layer was separated from water with chloroform and evaporated to dryness, and then purified using LMS solid phase extraction columns. The method is simple, requiring only small quantities of reagents and involves minimal manual work-up procedures. The lower limits of quantification were 1 ng/mL(g) for chloramphenicol and 5 ng/mL(g) for ketoprofen in milk and meat and 2 ng/g for chloramphenicol in egg and honey, and 3 ng/mL for chloramphenicol in urine.