Enrofloxacin Treatment Research Articles

Effect of a 5 day enrofloxacin treatment on Salmonella enterica serotype Typhimurium DT104 in the pig.

There are concerns that the use of enrofloxacin in livestock production may contribute to the development of fluoroquinolone resistance in zoonotic bacteria. The objective of our study was to investigate the effect of a single 5 day enrofloxacin treatment on Salmonella enterica serotype Typhimurium DT104 in a pig model. Our results showed that a single treatment failed to eradicate S. Typhimurium DT104, which continued to be isolated up to 35 days after treatment. We also provide evidence that treatment positively selects for S. Typhimurium DT104 strains that are already nalidixic acid resistant (gyrA Asn-87) or cyclohexane resistant, the latter being indicative of an up-regulated efflux pump. Emergence of fluoroquinolone resistance was not detected during treatment or post-treatment in any of the Salmonella strains monitored. However, the effect of enrofloxacin on the nalidixic acid-resistant and cyclohexane-resistant S. Typhimurium DT104 outlasted the current withdrawal time of 10 days for Baytril (commercial veterinary formulation of enrofloxacin). In conclusion, our study has provided direct evidence that enrofloxacin-treated pigs could be entering abattoirs with higher numbers of quinolone-resistant zoonotic bacteria than untreated pigs, increasing the risk of these entering the food chain.

Use of enrofloxacin for treatment of large-form Haemobartonella felis in experimentally infected cats.

To compare treatment with enrofloxacin and doxycycline with no treatment in cats experimentally infected with Haemobartonella felis. Prospective case-control study. 16 cats. Cats were inoculated with large-form H. felis from a chronically infected donor. Cats were assigned to 1 of 4 treatment groups: doxycycline (5 mg/kg [2.3 mg/lb], p.o., q 12 h), low-dose enrofloxacin (5 mg/kg, p.o., q 24 h), high-dose enrofloxacin (10 mg/kg [4.5 mg/lb], p.o., q 24 h), and an untreated control group. Clinical signs, Hct, blood smears, and a polymerase chain reaction (PCR) assay were used to monitor progression of the infection. All cats were confirmed to be infected with H. felis via blood smear evaluations and PCR assay results. Treatment had no effect on Hct during the intratreatment period, but Hct values were significantly greater in the low-dose enrofloxacin group, compared with the control group, during the posttreatment period. During the intratreatment period, H. felis organism counts per 1,000 RBC in the doxycycline treatment and the high-dose enrofloxacin treatment groups decreased at a significantly faster rate than those in the control group. In the posttreatment period, organism counts in the doxycycline treatment group and the low- and high-dose enrofloxacin groups decreased at significantly faster rates than counts in the control group. There was no significant effect of treatment on the number of positive PCR assay results. Two cats treated with enrofloxacin and 1 cat treated with doxycycline completely cleared the H. fe is organism despite presumed immunosuppression caused by glucocorticoids. Results support the hypothesis that enrofloxacin has anti-H. felis effects.

Effect of enrofloxacin treatment on plasma endotoxin during bovine Escherichia coli mastitis.

To investigate the effect of enrofloxacin on endotoxin resorption during bovine Escherichia coli mastitis. 12 healthy early post partum Holstein cows. Mastitis was induced by intramammary infusion of 10(4) cfu E. coli P4:032. Six cows were treated twice according to the usual enrofloxacin therapy: 5 mg/kg enrofloxacin 1) intravenously at 10 h and 2) subcutaneously at 30 h after challenge. The other 6 cows served as non-treated controls. Blood and milk samples were collected at several time points after challenge. LPS in plasma was quantified using the limulus amoebocyte lysate (LAL) assay. The somatic cell count (SCC) and cfu of milk samples were also analysed. Occasional LPS peaks were detected in the plasma of 2 control cows at 6 h post-challenge and of 1 enrofloxacin-treated cow at 10 h post-challenge (P < 0.01 and P < 0.05, respectively, in comparison with time 0), just before enrofloxacin treatment. After enrofloxacin treatment, no significant LPS amounts were detected in the plasma of treated cows, but neither in the control cows. During induced coliform mastitis, LPS resorption in plasma occured only sporadically and within 10 h post-challenge. Whereas enrofloxacin treatment clearly limited bacterial growth in milk, significant effects on LPS resorption could not be detected. This suggests that enrofloxacin treatment of E. coli mastitis is predominantly beneficial by its bactericidal activity and is not associated with enhanced resorption of endotoxins.

Ciprofloxacin resistance in Campylobacter jejuni evolves rapidly in chickens treated with fluoroquinolones.

Fluoroquinolones are commonly used to treat gastroenteritis caused by Campylobacter species. Domestically acquired fluoroquinolone-resistant Campylobacter infection has been documented recently in the United States. It has been proposed that the increase in resistance is due, in part, to the use of fluoroquinolones in poultry. In separate experiments, the effects of sarafloxacin and enrofloxacin treatment of Campylobacter jejuni-infected chickens on the development of ciprofloxacin resistance were measured. Fecal samples were collected before and after treatment and were cultured for C. jejuni. When enrofloxacin or sarafloxacin was used at US Food and Drug Administration-approved doses in broiler chickens, resistance developed rapidly and persisted in C. jejuni. MICs of ciprofloxacin increased from a base of 0.25 microg/mL to 32 microg/mL within the 5-day treatment time frame. These results show that the use of these drugs in chickens rapidly selects for resistant Campylobacter organisms and may result in less effective fluoroquinolone therapy for cases of human campylobacteriosis acquired from exposure to contaminated chicken.

Elimination of Pasteurella pneumotropica from a contaminated mouse colony by oral administration of Enrofloxacin.

Enrofloxacin, a fluoroquinolone bactericidal antibiotic, was administered in an attempt to eradicate Pasteurella pneumotropica (P. pneumotropica) from a contaminated mouse colony. Contaminated mice, maintained within 4 animal rooms, were administered Enrofloxacin in drinking water at a daily dosage of 25.5 mg/kg for 2 weeks. Following one week of Enrofloxacin treatment, mice were selected randomly from each room and examined for P. pneumotropica. This procedure was repeated two or three times until all mice examined tested negative for the Pasteurella strain. With the exception of one room, treated mice consistently tested negative for P. pneumotropica for up to 45 weeks following completion of Enrofloxacin treatment. Thus, oral administration of Enrofloxacin significantly eliminated P. pneumotropica from a contaminated mouse colony.

Tumor necrosis factor-α and nitrite/nitrate responses during acute mastitis induced by Escherichia coli infection and endotoxin in dairy cows

Concentrations of tumor necrosis factor-α (TNF-α) and of NO x (sum of nitrite and nitrate as indicators of endogenous nitric oxide production) in milk and blood plasma were measured in three mastitis models in dairy cows in early lactation. Escherichia coli P4:037 bacteria or endotoxin 0111:B4 were administered into both left quarters of 12 and 6 cows, respectively. Six of the E. coli-infected cows were treated with a bactericidal antibiotic (Enrofloxacin; Bayer AG, Leverkusen, Germany) i.v. at 10 hr and subcutaneously (sc) at 30 hr after infection. NO x concentrations transiently increased maximally 10- to 11-fold in milk of E. coli-infected quarters with or without antibiotic treatment at 24 hr and after endotoxin administration. NO x concentrations did not change in milk of unchallenged quarters and in blood plasma. Increases of NO x were proceeded by a transient (96- to 149-fold) rise of milk TNF-α concentrations, which in endotoxin-administered quarters was maximal at 6 hr and in infected quarters without or with Enrofloxacin treatment at 10 and 14 hr. In blood plasma TNF-α concentrations only moderately increased to peaks in endotoxin-administered cows at 6 hr and in E. coli-infected cows at 14 hr postchallenge. In one severely sick, nontreated E. coli-infected cow milk, TNF-α response at 14 hr was excessive and followed by a spectacular rise of NO x concentration in milk between 48 and 72 hr. In conclusion, a possible clinical relevance of nitric oxide production associated with a rise of intramammary and systemic TNF-α during acute mastitis by E. coli infection and endotoxin in lactating dairy cows is indicated, but could not be inhibited by antibiotic treatment.

Elimination of early Salmonella enteritidis infection after treatment with competitive-exclusion culture and enrofloxacin in experimentally infected chicks

The effect of normal avian gut flora (NAGF) and enrofloxacin administration on the early infection of young chicks by Salmonella enteritidis (SE) was determined using day-old White Leghorn chicks. Day- old chicks were divided into two groups, untreated control and NAGF-treated, and then infected with 10(6) cfu of SE per chick by oral gavage. The untreated, infected chicks were further divided into two groups and were either left untreated or medicated with a regimen of 10 mg/kg of enrofloxacin in drinking water daily for 10 d, followed by two doses of NAGF beginning at 10 and 8 wk of age in Trial 1 and Trial 2, respectively. Liver, spleen, and cecum samples were tested for the presence of SE, and immunological responsiveness was investigated up to 12 wk of age. Compared with the untreated group, the cecal colonization of SE was significantly (P < 0.05) decreased in the NAGF-treated group in Trials 1 and 2. No significant differences in organ infection were observed in the NAGF-treated vs. untreated birds. Although a significant effect of the combined treatment of enrofloxacin treatment and NAGF on the early infection was not shown in Trial 1, compared with enrofloxacin only or the untreated group, a significant reduction (P < 0.05) in the number of infected chickens and in the number of SE in the cecal contents was observed at 10 wk of age in Trial 2. The enrofloxacin treatment did not increase opportunistic colonization by SE due to the use of the antibiotic in either trial. The plasma and intestinal immunological responses were not significant at the early age (up to 12 wk) of the birds. The use of enrofloxacin, followed by NAGF, could aid the elimination of SE from young chicks persistently infected at an early age. The combined treatment, compared with enrofloxacin alone, protected chickens from reinfection by 40%.

Use of Enrofloxacin to Control AtypicalAeromonas salmonicidain Atlantic Tomcod

Abstract The antimicrobial enrofloxacin was tested for its ability to control atypical Aeromonas salmonicida in Atlantic tomcod (Microgadus tomcod). An initial experiment showed that a single injection of enrofloxacin, at a dosage of approximately 5 mg active ingredient per kilogram of fish, prevented the formation of characteristic furunculosis lesions but did not significantly reduce mortality during a 76-d period. In a second experiment, in which we administered the antimicrobial at days 1, 10, and 45, treated fish experienced significantly lower mortality than did the control fish. Three of 10 necropsied fish treated with enrofloxacin produced positive cultures of atypical A. salmonicida, whereas the pathogen was successfully cultured from 7 of 10 control fish. Cultures were obtained from skin lesions or from infected areas of buccal or caudal regions. Sixteen of 50 (32%) fish from the enrofloxacin treatment died during the experiment, and 30% of the dead fish displayed circular lesions on the trunk. ...

Derivation of Pasteurella multocida-free rabbit litters by enrofloxacin treatment

Pasteurella multocida is an important bacterial pathogen of rabbits that is easily transmitted from infected does to their kits prior to weaning. Enrofloxacin, a flouroquinolone antibiotic, is effective at limiting nasal carriage of P. multocida in rabbits. To determine if enrofloxacin treatment of pregnant does infected with P. multocida can be used to produce P. multocida-free litters, groups of 3 rabbits were inoculated intranasally on day 10 of gestation with 1.0 × 10 6 P. multocida CFUs. Beginning on day 14, one group received enrofloxacin IM (5 mgkg −1, BID), and a second group received enrofloxacin in the drinking water (200 mgl −1). IM treatment continued until kindling, while PO treatment continued 1 week after kindling. A third group was infected but received only IM saline, and a fourth group was infected but not treated. In addition, a fifth group was neither infected nor treated. Culture of nasal lavage samples and tissues from does and kits showed that both routes of enrofloxacin treatment failed to completely eliminate P. multocida from does, but all kits from enrofloxacin-treated does were free from P. multocida. These results suggest that treatment of does with enrofloxacin during the periparturient period may interrupt transmission of P. multocida from infected does to their kits and that this treatment may be useful for deriving Pasteurella-free rabbits from infected does.

Determination of an effective sampling regime to detect salmonella enteritidis in the environment of poultry units

A study of the dissemination of Salmonella enteritidis in the poultry breeder industry in the UK showed that the choice of sites for sampling the environment of occupied houses and empty houses which had been disinfected after depopulation had a significant influence on the outcome. Increased isolation rates could be achieved by sampling nest box floors and dust in open slave feed hoppers in occupied poultry houses. Nest box floors were the most sensitive sites for detection of residual environmental contamination in poultry houses where enrofloxacin treatment had been used. Floor sweepings, nest box floors, slave feed hoppers, hydrated wall fabric junctions and high beams and pipes were the most sensitive sample sites in cleansed and disinfected poultry houses. The use of universal disinfectant neutralisers gave good results in laboratory trials but appeared to reduce the isolation rate from field samples.

Successful therapy of furunculosis in Atlantic salmon, Salmo salar L., using the fluoroquinolone antimicrobial agent enrofloxacin

Abstract An outbreak of furunculosis was diagnosed in an Atlantic salmon, Salmo salar L., commercial sea‐pen farm and treated with the fluoroquinolone antimicrobial enrofloxacin. The affected post‐smolt, adult fish and broodstock readily consumed pelleted feed impregnated with enrofloxacin at concentrations of 1000, 1300 and 2000ppm, respectively, daily for 10 days. Mortalities of infected post‐smolts were reduced from an average of 5.8% per month for the 2 months preceding therapy to 0.6% per month for the 2 months following therapy. Infected adult fish had a 2 month mean mortality rate of 2.6% prior to enrofloxacin treatment and 0.3% over the 2 months subsequent to therapy. Apparently noninfected (nonclinical) fish in the same farm exhibited an average monthly mortality of 0.4% over the 4‐month study period. Sea water temperatures gradually rose from less than 2°C in March to approximately 12°C in September. Mean antimicrobial tissue concentrations over the 10 complete days of medication were 4.58, 7.32, 4.58, 8.89 and 3.40ppm for muscle, skin plus fat, liver, kidney and gill, respectively. Within 24h of consuming medicated feed, tissue concentrations of antimicrobial were nearly 66% of the average concentrations for the medication period. Half‐lives of elimination for the antimicrobial residues were approximately 2 days for liver, 3 days for kidney, 6 days for gill, 11 days for muscle and 22 days for skin plus fat. The producers reported a successful harvest after a 180‐day medication‐free period.