Feeding Tetracycline Research Articles

High Prevalence of Fluoroquinolone-Resistant Campylobacter Bacteria in Sheep and Increased Campylobacter Counts in the Bile and Gallbladders of Sheep Medicated with Tetracycline in Feed.

Campylobacter is a major foodborne pathogen in humans and a significant cause of abortion in sheep. Although ruminants are increasingly recognized as important reservoirs for Campylobacter species, limited information is available about the molecular epidemiology and antimicrobial resistance (AMR) profiles of sheep Campylobacter Here, we describe a two-trial study that examined Campylobacter profiles in sheep and determined whether in-feed tetracycline (TET) influenced the distribution and AMR profiles of Campylobacter Each trial involved 80 commercial sheep naturally infected with Campylobacter: 40 of these sheep were medicated with tetracycline in feed, while the other 40 received feed without antibiotics. Fecal and bile samples were collected for the isolation of Campylobacter The bacterial isolates were analyzed for antimicrobial susceptibility and genotypes. The results revealed that 87.0% and 61.3% of the fecal and bile samples were positive for Campylobacter (Campylobacter jejuni and Campylobacter coli), with no significant differences between the medicated and nonmedicated groups. All but one of the tested Campylobacter isolates were resistant to tetracycline. Although fluoroquinolone (FQ) resistance remained low in C. jejuni (1.7%), 95.0% of the C. coli isolates were resistant to FQ. Genotyping revealed that C. jejuni sequence type 2862 (ST2862) and C. coli ST902 were the predominant genotypes in the sheep. Feed medication with tetracycline did not affect the overall prevalence, species distribution, and AMR profiles of Campylobacter, but it did increase the total Campylobacter counts in bile and gallbladder. These findings identify predominant Campylobacter clones, reveal the high prevalence of FQ-resistant C. coli, and provide new insights into the epidemiology of Campylobacter in sheep.IMPORTANCECampylobacter is a major cause of foodborne illness in humans, and antibiotic-resistant Campylobacter is considered a serious threat to public health in the United States and worldwide. As a foodborne pathogen, Campylobacter commonly exists in the intestinal tract of ruminant animals, such as sheep and cattle. Results from this study reveal the predominant genotypes and high prevalence of tetracycline (TET) and fluoroquinolone (FQ) resistance in sheep Campylobacter The finding on fluoroquinolone resistance in sheep Campylobacter is unexpected, as this class of antibiotics is not used for sheep in the United States, and it may suggest the transmission of fluoroquinolone-resistant Campylobacter from cattle to sheep. Additionally, the results demonstrate that in-feed medication with tetracycline increases Campylobacter counts in gallbladders, suggesting that the antibiotic promotes Campylobacter colonization of the gallbladder. These findings provide new information on Campylobacter epidemiology in sheep, which may be useful for curbing the spread of antibiotic-resistant Campylobacter in animal reservoirs.

Analysis of Tetracyclines in Medicated Feed for Food Animal Production by HPLC-MS/MS.

The use of medicated feed is a common practice in animal food production to improve animal health. Tetracyclines and β-Lactams are the groups that are most frequently added to this type of feed. The measurement of the concentration of the analytes in these types of samples is sometimes due to the matrix characteristic, and manufacturers are demanding fast, precise and reproducible methods. A rapid confirmatory method based on a simple extraction protocol using acidified methanol and followed by high performance liquid chromatography coupled to a tandem mass spectrometer for the quantification of four tetracyclines in feed is presented. Validation was performed following the guidelines of Decision 2002/657/EC. Results indicated that the four tetracyclines can be identified and quantified in a concentration range between 50 and 500 mg/kg with recoveries between 84% and 109% and RSD for precision under reproducible conditions between 12% and 16%. Satisfactory results were also obtained with interlaboratory studies and by comparing the method with an HPLC-Fluorescent method.

Ion Suppression Study for Tetracyclines in Feed

Ion suppression in analysis of tetracyclines in feed was studied. The conventional analysis consists of a liquid extraction followed by a clean-up step using solid phase extraction (SPE) technique and analysis of the tetracyclines by liquid chromatography and mass spectrometric detection. Various strategies for extraction and cleanup were tested in the present work, and the effectiveness to decrease the ion suppression on the MS/MS signals was evaluated. Four sample treatment methods were tested with five different feed samples. Extraction solvents tested were McIlvaine buffer and a mixture of McIlvaine buffer dichloromethane (3 : 1). SPE cartridges for cleanup were Oasis HLB, Oasis MCX, and Oasis MAX. The effectiveness of the methods was evaluated in terms of decreasing the ion suppression effect but also of decreasing the variability of ion suppression between samples. The method that provided the most satisfactory results involved a clean-up step based on SPE using mixed-mode cation exchange cartridges (Oasis MCX).

The Effect of Antibiotics and lonophores on the Gain of Stocker Cattle Grazing Native Grass Pasture

AbstractThe feeding of antibiotics or ionophores in free-choice mineral mixtures was evaluated in four studies with stockers (heifers and steers) grazing native range. In trial 1, heifers with access to lasalocid in a free-choice mineral mixture consumed more mineral (P<.05) and had greater gains (P<.10) than heifers offered monensin mixtures. In trial 2, heifers consuming mineral mixtures containing either oxytetracycline or lasalocid were similar (P>.05) in daily gain and in ruminal propionic acid. Both groups gained more (P<.01) than the controls (salt-dicalcium phosphate). In trial 3, the combination of lasalocid and chlortetracycline in a free-choice mineral mixture resulted in greater gains (P<.08) than chlortetracycline alone but was not different from lasalocid. In trial 4, the combination of lasalocid and oxytetracycline in a free-choice mineral mixture resulted in greater gain (P<.05) than with lasalocid alone but was not different from oxytetracycline. There is little difference in cattle gains between feeding tetracycline or an ionophore in a mineral mixture. Lasalocid and tetracycline fed in combination appear to improve gain over feeding each singly, but they are not presently cleared for feed manufacturers to mix the combination into supplements for grazing cattle.

The cost of anaplasmosis in the Red River Plains and south-east areas of Louisiana.

Losses from morbidity and mortality due to anaplasmosis were assessed in beef and dairy cattle of the Red River Plains and south-east areas of Louisiana. The cost of treatment and prevention of anaplasmosis and losses in milk production and those due to deaths or culling were valued at $0.5 million for the year 1983 in these two areas. The cost of prevention included the use of tetracyclines in feed and salt-mineral supplements, injectable tetracycline, vaccination and an estimated 10% of the cost of insecticidal ear tags, sprays, pour-on applications and dust bags. The remainder of these costs and the total cost of vector control in dairy cattle was attributed to the control of fly annoyance. Treatment costs included veterinary fees and the owner's treatment costs, including labour costs.

Role of bacteria in maintaining the redox potential in the hindgut of termites and preventing entry of foreign bacteria

The hindgut of the lower termites, Mastotermes darwiniensis and Coptotermes lacteus and the higher termite Nasutitermes exitiosus were made aerobic by exposure of the termites to pure oxygen, a procedure which killed their spirochaetes and their protozoa (lower termites only). The time taken for the hindgut to become anaerobic after the termites were restored to normal atmospheric conditions ranged from 2 to 4.5 hr. After oxygen treatment the number of gut bacteria increased some six- to ten-fold in all termite species, indicating that the bacteria are poised to use oxygen entering the gut. Removal of all the hindgut microbiota by feeding tetracycline caused the hindgut to become aerobic in M. darwiniensis and N. exitiosus. The transferring of M. darwiniensis to fresh wood, free of antibiotic, resulted in the return of the normal flora and the eventual establishment of anaerobic conditions in the hindgut. Thus the bacteria appear to be important in maintaining anaerobic conditions in the gut. Attempts to determine whether the protozoa (in the lower termites) played any part in maintaining the Eh of the hindgut were unsuccessful. Serratia marcescens failed to colonise the gut of normal C. lacteus and transiently colonized (for 5 days) the gut of normal N. exitiosus. Transient colonization by S. marcescens (from 6 to 10 days) occurred in N. exitiosus when its hindgut spirochaetes were killed and in C. lacteus when its spirochaetes and protozoa were killed, indicating a possible role for the spirochaetes and/or protozoa in influencing the bacteria allowed to reside in the hindgut. Exposure of normal termites to Serratia provoked an increase in the numbers of the normal gut bacteria.

The origin and distribution of cellulase in the termites, Nasutitermes exitiosus and Coptotermes lacteus

The cellulase of the higher termite Nasutitermes exitiosus was located in the foregut (19%), the midgut (59%), the mixed segment (14%) and in the hindgut (8%). Removal of the gut flora by feeding tetracycline or by starving the termite did not affect the activity of the enzymes indicating that the termite secretes its own cellulase and is not dependent on its gut flora for the digestion of cellulose. The cellulase of the lower termite Coptotermes lacteus was distributed through the foregut (19%), midgut (32%) and hindgut (49%). Removal of the gut flora and fauna, left the specific activity of the cellulase of the fore- and mid-gut largely unaffected, but led to a 20% decrease in the specific activity of the cellulase in the hindgut. In starved C. lacteus the distribution of cellulase activity was foregut, 44%; midgut, 30% and hindgut, 26%. These results indicate that C. lacteus synthesises its own cellulase in addition to using the gut protozoa for cellulose digestion.