Effect of Antibiotics in Extender on Bacterial and Spermatozoal Quality of Cooled Buffalo (Bubalus bubalis) Bull Semen

The present study was designed to study the effect of traditional antibiotic combination (streptomycin and penicillin; SP) and relatively modern combination of antibiotics (gentamycin, tylosin, lincomycin and spectinomycin; GTLS) in extender on bacterial control and spermatozoal quality of liquid buffalo bull semen stored at 5°C. Semen collected from Nili‐Ravi buffalo bulls (n = 10) was diluted with skim milk extender containing either SP (streptomycin 1000 μg/ml and penicillin 1000 IU/ml), GTLS (gentamycin 500 μg/ml, tylosin 100 μg/ml, lincomycin 300 μg/ml and spectinomycin 600 μg/ml) or negative control with no antibiotics (NA). Liquid semen was stored at 5°C for 5 days. Aerobic bacteria isolated from buffalo semen were Pseudomonas aeruginosa and Staphylococcus aureus. The only facultative anaerobic bacterium isolated was Klebsiella pneumoniae. In vitro antibiotic sensitivity test revealed that Ps. aeruginosa and Staph. aureus were susceptible to gentamycin. Staphylococcus aureus and K. pneumoniae were susceptible to tylosin and linco‐spectinomycin. Total aerobic bacterial count was significantly lower in semen samples treated with GTLS than those of SP on third and fifth day of storage at 5°C. There was no difference (p > 0.05) in sperm motility, longevity and plasma membrane integrity (PMI) in extender containing SP or GTLS combination until the third day of storage at 5°C. On fifth day of storage sperm motility, longevity and PMI was significantly better in extender containing SP compared with GTLS and NA. Intact acrosomes, and sperm head, mid piece and tail abnormalities remained similar (p > 0.05) because of antibiotics up to 5 days of storage. In conclusion, GTLS is more capable than SP for bacterial control of buffalo bull semen. Moreover, GTLS and SP are equally efficient in preserving spermatozoal quality of extended buffalo bull semen for 3 days at 5°C.     

Comparisons of antibiotic combinations to control Pseudomonas aeruginosa in bovine semen.

Raw semen experimentally contaminated with 10(6) Pseudomonas aeruginosa cells per milliliter was processed for use in artificial insemination (AI) using three different antibiotic combinations: a) gentamicin, lincomycin, spectinomycin and tylosin (GLST) directly added to contaminated raw semen followed by dilution with whole milk or egg yolk Tris containing GLST; b) penicillin, streptomycin, lincomycin, spectinomycin and minocycline (PSLSM) in whole milk used to dilute the contaminated raw semen followed by further dilution with glycerolated milk containing PSLSM; and c) penicillin, streptomycin, lincomycin and spectinomycin (PSLS) used with egg yolk Tris diluent in the same way as PSLSM and milk. Diluted semen was incubated at 35 degrees C for 5 or 40 min before cooling commenced. To assess the efficacy of the antibiotics in controlling P. aeruginosa, diluted semen samples were cultured for the organism before and after freezing. The GLST antibiotics added to raw semen and milk reduced the counts of P. aeruginosa before or after freezing. When egg yolk Tris was used, GLST inhibited the organism as indicated by its low growth in culture before freezing and absence of growth from samples after freezing. With PSLSM and PSLS treatments, the organism was recovered in milk and egg yolk Tris processed semen both before and after freezing. However, incubation at 35 degrees C for 40 min prior to cooling, compared to incubation of 5 min, appeared to reduce the bacterial counts after freezing.     

Cooled Storage of Canine Semen: in vitro Effects of Different Concentrations of an Antibiotic Combination on Growth of Mollicutes

The aim of this study was to examine effects of an antibiotic combination at different concentrations on growth of mycoplasma and ureaplasma during cooled storage of canine semen (n = 20). Semen aliquots were diluted with Tris–citric acid–fructose–egg yolk extender containing either 1.0 g/l streptomycin and 0.6 g/l benzylpenicillin (control) or a combination of gentamycin, tylosin, lincomycin and spectinomycin (GTLS‐1: 0.25, 0.05, 0.15 and 0.3; GTLS‐2: 0.5, 0.1, 0.3 and 0.6; GTLS‐3: 1.0, 0.2, 0.6 and 1.2 g/l). Samples were assessed for motility and membrane integrity by computer‐assisted sperm analysis immediately after dilution and at 24, 48 and 72 h of cooled storage. Morphologically, normal spermatozoa were determined, and bacterial culture was performed at 24 and 72 h. Mycoplasma spp. were detected in 14 of 20 ejaculates (70%) with severe growth in 12 samples. A reduction but not total elimination of mycoplasma growth occurred in all GTLS extenders with the most pronounced reduction in group GTLS‐3 (control vs GTLS‐1 and GTLS‐2 p < 0.05, control vs GTLS‐3 p < 0.001). Ureaplasmas were detected in four ejaculates, and growth was reduced to the same extent in GTLS and control extender. Progressive motility in all groups, total motility in groups GTLS 1–3 and percentage of membrane‐intact spermatozoa in groups GTLS 2 and 3 decreased slightly (p < 0.05) over time. In conclusion, dilution of canine semen with GTLS extender has no major detrimental effects on spermatozoa during cooled storage. It reduced the growth but did not totally eliminate mycoplasmas and ureaplasmas from cooled‐stored dog semen.     

Antimicrobial susceptibility testing of German Campylobacter fetus subsp. venerealis isolates by agar disk diffusion method

Campylobacter fetus subsp. venerealis is the causative agent of bovine genital campylobacteriosis and is transmitted by asymptomatic carrier bulls via contaminated semen during artificial insemination. The aim of the present study was to determine the in vitro susceptibility of Campylobacter fetus subsp. venerealis isolated from bovine specimens in the years from 2000 to 2009 in Germany to antibiotics generally used in semen treatment. The susceptibilities of 50 strains to spectinomycin (10 microg), gentamicin (10 microg), streptomycin (25 microg), penicillin (10 microg), lincomycin (10 microg), ciprofloxacin (5 microg), erythromycin (30 microg) and tetracycline (30 microg) were determined using a disk diffusion susceptibility test. All strains were susceptible to gentamicin. A considerably reduced susceptibility to one or more antimicrobial agents was detected in seven out of 50 isolates (14%) with the most frequent reduction in susceptibility to lincomycin and spectinomycin. Furthermore, strains with reduced susceptibility to more than one antimicrobial agent were always associated with reduced susceptibility to lincomycin. It is recommended to determine the antimicrobial susceptibility of Campylobacter fetus subsp. venerealis isolates in order to evaluate the efficacy of the generally used antibiotic treatment of bull semen and to detect possible resistances.     

Antibiotic susceptibilities of recent isolates of Mycoplasma bovis in Belgium

The susceptibilities of 40 recent Belgian field isolates of Mycoplasma bovis to 10 antimicrobial agents were assessed. Tiamulin was the most active antimicrobial agent against M bovis, with an initial inhibitory concentration (IIC50) of 0.06 microg/ml, but it is not licensed for the treatment of cattle. All three fluoroquinolones tested (danofloxacin, enrofloxacin and marbofloxacin) were effective against strains of M bovis, and had a minimum mycoplasmacidal concentration (MMC50) less than or equal to 1 microg/ml. Gentamicin was poorly effective, having an IIC50 of 8 microg/ml. Many strains of M bovis were resistant to tylosin, spectinomycin, lincomycin, tetracycline and oxytetracycline.     

The immunohistochemical detection of Mycoplasma bovis and bovine viral diarrhea virus in tissues of feedlot cattle with chronic, unresponsive respiratory disease and/or arthritis.

The purpose of this study was to determine the frequency of selected pathogens in the tissues of a group of feedlot cattle with chronic disease (most often respiratory disease and/or arthritis). Samples of lung and joint tissues from 49 feedlot animals that had failed to respond to antibiotic therapy were tested by immunohistochemical staining for the antigens of Mycoplasma bovis, Haemophilus somnus, Pasteurella (Mannheimia) hemolytica, and bovine viral diarrhea virus (BVDV). Mycoplasma bovis was demonstrated in over 80% of cases, including in 45% of joints and 71% of lungs tested. Mycoplasma bovis was the only bacterial pathogen identified in the joints. Haemophilus somnus and Pasteurella (Mannheimia) haemolytica were found in 14% and 23% of cases, respectively, and were confined to the lungs in all instances. Infection with BVDV was demonstrated in over 40% of cases. Mycoplasma bovis and BVDV were the most common pathogens persisting in the tissues of these animals that had failed to respond to antibiotic therapy.     

Control of Campylobacter fetus in artificially contaminated bovine semen by incubation with antibiotics before freezing

Fresh, diluted semen containing 1.55 X 10(6) cfu/ml of Campylobacter fetus subsp. venerealis was incubated with 500 iu of penicillin, 500 micrograms of streptomycin, 160 micrograms of lincomycin and 300 micrograms of spectinomycin per ml at 35 degrees C for 0, 1, 2, 5, 10, 20 or 40 minutes. The semen was cooled to 5 degrees C, packaged in 0.25 ml French straws and then frozen in liquid nitrogen for 2 weeks. Immediately after thawing and removal of the antibiotics by centrifugation semen samples from each of the seven treatment groups were cultured as for C. fetus. Semen samples were also examined by in-vitro tests for sperm motility prior to and post-freezing. Incubation with the antibiotics for 5, 10, 20 or 40 min prior to freezing reduced the numbers of C. fetus in the semen to non-detectable levels in 38%, 69%, 88% and 100% of samples respectively. The incubated semen showed no significant reduction of sperm motility although fertility trials have not been done.     

Factors associated with the effectiveness of antibiotic treatment for ovine virulent footrot

Factors associated with the proportion of sheep cured of virulent footrot after antibiotic treatment were studied in a field trial under dry environmental conditions. From 2 similar flocks, 1091 Merino sheep weighing about 50 kg and infected with virulent footrot received an intramuscular injection of either 12 mL of a mixture of penicillin (250 mg/mL) and streptomycin (250 mg/mL), 6 mL of long acting oxytetracycline (200 mg/mL) or 6 mL of a mixture of lincomycin (50 mg/mL) and spectinomycin (100 mg/mL). Variables that were significantly associated with the proportion of sheep cured were: the type of antibiotic used, the number of feet infected and the flock from which the sheep came. There was an interaction between antibiotic type and number of feet infected and between antibiotic type and flock in association with the proportion of sheep cured. The extent of paring and the occurrence of blowfly strike in footrot lesions treated with diazinon had no significant association with the proportion of sheep cured.     

Influence of antibiotic therapy on serum levels of reactive oxygen species in ovariectomized bitches

This study was conducted on 60 ovariectomized bitches. The objectives were to measure the mean reactive oxygen species (ROS) concentrations before, during and after surgery, and to investigate the effect of the administration of five different antibiotic treatments: amoxicillin, benzylpenicillin/dihydrostreptomycin, sulfametazine/sulfamerazine/sulfathiazole, enrofloxacin, lincomycin/spectinomycin. The first value recorded represented the mean ROS concentration in anestral bitches and constitutes a reference level with which to compare the subsequent measurements. After premedication, induction of anesthesia and during maintenance and surgery, ROS serum concentrations showed constant values until the end of surgery. After surgery and during antibiotic administration, an increase in ROS concentration occurred, which differed among the five groups in relation to the antibiotics employed. The lowest increases occurred in the groups treated with the combination of lincomycin/spectinomycin, and with amoxicillin; whereas the highest increases were detected in the group treated with enrofloxacin. The three other antibiotics showed an intermediate level of influence on oxidative status.     

In vitro susceptibilities of field isolates of Mycoplasma agalactiae to oxytetracycline,tylosin, enrofloxacin,spiramycin and lincomycin-spectinomycin

The minimum inhibitory concentrations (MICs) of tetracycline, enrofloxacin, tylosin, spiramycin and a lincomycin:spectinomycin 1:2 combination, against 24 Sicilian isolates of Mycoplasma agalactiae, the causative organism of contagious agalactia were determined in vitro by a broth dilution method. Enrofloxacin was the most effective antimicrobial in vitro with a range of MIC values from 0.125 to 0.500 microg/ml and an MIC(50) of 0.203 and MIC(90) of 0.365 microg/ml. Using the MIC(50) and MIC(90) values the remaining four antimicrobials are ranked in order of in vitro effectiveness as follows: tylosin (MIC(50)0.292; MIC(90)0.525 microg/ml) was slightly more effective than tetracycline (MIC(50)0.296; MIC(90)0.533 microg/ml), followed by lincomycin:spectinomycin (MIC(50)0.521; MIC(90)0.938 microg/ml) and spiramycin (MIC(50)1.583; MIC(90)2.850 microg/ml). MIC values above 1.000 microg/ml were obtained using tetracycline, tylosin and spiramycin for some M. agalactiae isolates.     

Lincomycin and spectinomycin in the treatment of breeding rams with semen contaminated with ureaplasmas

Ureaplasma species were isolated from semen samples collected sequentially from one Awassi and three Assaf breeding rams. Each ram was injected subcutaneously with an aqueous solution of lincomycin and spectinomycin for five consecutive days at a dose equivalent to 4·5 mg kg⁻¹ lincomycin and 9·0 mg kg⁻¹ spectinomycin daily. Serum and semen samples were collected at intervals during the treatment and assayed for lincomycin. No Ureaplasma species were isolated from semen samples collected during the course of the treatment and at intervals for 17 days after the last treatment. The concentration of lincomycin in semen ranged from 0·51 μg ml⁻¹ four hours after treatment to 0·08 μg ml⁻¹ 24 hours after treatment, and these levels were three to nine times higher than the corresponding serum concentrations.     

Clinical pharmacology of tiamulin in ruminants

Median values for the minimum inhibitory concentrations (MIC) of tiamulin for Mycoplasma and Acholeplasma isolated from ruminants were 0.05 μg/ml and 0.025 μg/ml, respectively. These values were close to the MIC values of tylosin and considerably lower than the respective values for spectinomycin, spiramycin and oxytetracycline.     

Therapeutic Effect of Lincomycin and Spectinomycin Water Medication on Swine Dysentery

The therapeutic effects of various water medications on swine dysentery were determined in 223 pigs under controlled conditions. Carrier pigs were mixed with test animals until the disease was established. Lincomycin (22 mg/liter), spectinomycin (44 mg/liter) alone and lincomycin and spectinomycin in combination (66 mg/liter) and sodium arsanilate (161 mg/liter) in drinking water for seven days were the drugs evaluated. Negative and positive controls were also included. The experiment was terminated 41 to 43 days after initial medication. Mortality, mean value for stool consistency, incidence of dysenteric days and gross lesions of swine dysentery were the parameters measured for each treatment group.

The lincomycin-spectinomycin water medication was effective for the treatment of swine dysentery. Pigs treated with lincomycin-spectinomycin had a higher survival rate, a lower incidence of dysenteric days and fewer gross lesions of swine dysentery than pigs treated with sodium arsanilate, lincomycin or spectinomycin alone or the infected controls (P < 0.05).

     

Effect of eCG Superstimulation and Buserelin on Cumulus–Oocyte Complexes Recovery and Maturation in Llamas (Lama glama)

The aim of the present study was two fold. Experiment I: evaluate the effect of buserelin on llama's oocyte maturation after exogenous follicular activity suppression, followed by ovarian superstimulation with different doses of equine chorionic gonadotropin (eCG). Experiment II: compare the number of follicles aspirated and the number of cumulus–oocyte complexes (COCs) recovered according to different doses of eCG followed by buserelin. Experiment I consisted in a control group (without buserelin) and a treatment group (with buserelin), both subdivided according to eCG dose administered: A: 500 IU; B: 1000 IU; C: 1500 IU. The treatment group received a single i.v. dose of 8 μg of buserelin when two or more dominant follicles were found at ultrasound evaluation and 20 h later were subjected to surgery. In group A, 83% of the llamas did not respond to superstimulation. In groups B and C differences were observed between the control and the treatment groups for the degree of COCs maturation (p < 0.05). In experiment II animals were divided into two groups according to the eCG dose administered: 1000 and 1500 IU. Twenty hours before surgery females received a single i.v. dose of 8 μg of buserelin. Average number of follicles aspirated and COCs recovered was higher (p < 0.05) with the administration of 1500 IU of eCG. A larger number of expanded COCs were obtained from follicles ≥7 mm in diameter. We conclude that buserelin aids the recovery of a larger number of expanded COCs. Administration of 1500 IU of eCG produces a higher number of follicles for aspiration and number of COCs recovered.     

Clinical pharmacology of polymyxin B, colistin and colistimethate in young dairy calves

The in vitro sensitivity of 592 Gram-negative bacteria isolated from cattle against polymyxin B was determined by the agar plate dilution method. The minimal inhibitory concentration of polymyxin B for all but ten of the isolates was ≤ 2.0 μg/ml and 75% of the isolates were inhibited at 1.0 μg of polymyxin B/ml or less. Intramuscular injections of polymyxin B, colistin and colistimethate (CMS) were given to veal calves once daily for 3 days. Mean peak serum drug concentrations were observed within 0.5–1 h after treatment and were between 2.7 and 4.7 μg/ml when polymyxin B and colistin were administered at a dose rate of 2.5 mg/kg/day, and between 5.3 and 7.5 μg/ml at dose rate of 5.0 mg/kg/day. When CMS was given at 5.0 mg/kg/day mean peak drug concentration was 14.1 μg/ml. The elimination half-life ( t _1/2) of polymyxin B and colistin was 4–5 h but was approximately 2 h for CMS. Kidney function tests, using the double isotope single-injection method, were performed before and after the course of antibiotic treatment. No changes were detected in the glomerular filtration rate (GFR) or the effective renal plasma flow (ERPF) and blood urea levels were not raised following treatment. Several calves treated with the higher doses of polymyxin B and colistin exhibited transient ataxia and apathy 2–4 h after treatment but clinical signs suggesting interference with neurological function were not observed after an equivalent dose of CMS was administered.     

Elevation and prolongation of serum ampicillin and amoxycillin concentrations in calves by the concomitant administration of probenecid

The effects of probenecid on serum ampicillin and amoxycillin concentrations were investigated in 1–5 week old calves after oral and parenteral drug administration. Ampicillin trihydrate was administered orally at 250mg/calf, after an overnight fast, alone and with 1.5g probenecid. Peak serum ampicillin concentrations were elevated from 0.60 to 1.22 μg/ml by the co-administration of probenecid. In calves given 0.5 g amoxycillin trihydrate with the milk replacer, peak serum drug concentration increased from 1.74 to 3.16 μg/ml when 1.5 g probenecid was given too. Maximal effect of probenecid administered orally was with the 1.5 g/calf dose with considerably lesser increase in peak serum amoxycillin being observed with doses of 0.5 g, 1 g and 2 g/calf. After parenteral injection of probenecid solution at 1 g and 2 g/calf serum ampicillin concentrations peaked at more than twice the concentrations measured after equal doses of the two antibiotics were injected alone. The co-administration of 2 g probenecid and 1 g sodium ampicillin or 0.5 g sodium amoxycillin parenterally resulted in peak antibiotic concentrations considered to be effective against some of the more resistant pathogenic Gram-negative bacteria associated with diseases in calves and serum antibiotic concentrations 5 μg/ml were maintained during 5–6 h as opposed to 2–3 h after the antibiotics were injected alone. Oral administration of 1.5 g probenecid at three consecutive milk feeding times did not alter serum urea or serum creatinine concentrations.     

Bioavailability of spiramycin and lincomycin after oral administration to fed and fasted pigs

The disposition of spiramycin and lincomycin was measured after intravenous (i.v.) and oral (p.o.) administration to pigs. Twelve healthy pigs (six for each compound) weighing 16–43 kg received a dose of 10 mg/kg intravenously, and 55 mg/kg (spiramycin) or 33 mg/kg (lincomycin) orally in both a fasted and a fed condition in a three-way cross-over design. Spiramycin was detectable in plasma up to 30 h after intravenous and oral administration to both fasted and fed pigs, whereas lincomycin was detected for only 12 h after intravenous administration and up to 15 h after oral administration. The volume of distribution was 5.6 ± 1.5 and 1.1 ± 0.2 L/kg body weight for spiramycin and lincomycin, respectively. For both compounds the bioavailability was strongly dependent on the presence of food in the gastrointestinal tract. For spiramycin the bioavailability was determined to be 60% and 24% in fasted and fed pigs, respectively, whereas the corresponding figures for lincomycin were 73% and 41%. The maximum plasma concentration of spiramycin (C_max) was estimated to be 5 μg/mL in fasted pigs and 1 μg/mL only in fed pigs. It is concluded that an oral dose of 55 mg/kg body weight is not enough to give a therapeutically effective plasma concentration of spiramycin against species of Mycoplasma, Streptoccocus, Staphylococcus and Pasteurella multocida. The maximum plasma concentration of lincomycin was estimated to be 8 μg/mL in fasted pigs and 5 μg/mL in fed pigs, but as the minimum inhibitory concentration for lincomycin against Actinobacillus pleuropneumoniae and P. multocida is higher than 32 μg/mL a therapeutically effective plasma concentration could not be obtained following oral administration of the drug. For Mycoplasma the MIC₉₀ is below 1 μg/mL and a therapeutically effective plasma concentration of lincomycin was thus obtained after oral administration to both fed and fasted pigs.     

Antibiotic Resistance of Vibrio anguillarum,in Relation to Serovar and Plasmid Contents

A total of 520 Vibrio anguillarum strains, isolated from fish and the environment, were tested for their sensitivity to 20 different antibiotics. Most isolates were of European origin. The results were compared with data on the O-serogroup and plasmid contents. All strains were sensitive to neomycin, spectinomycin, nitrofurantoin, flumequine and oxolinic acid, while most strains were sensitive to streptomycin, Oxytetracycline, chloramphenicol, sulphonamides, trimethoprim, sulphonamides with trimethoprim, nalidixan, rifampicin, novobiocin and O/129. A major part of the strains were resistant to the macrolides, spiramycin and lincomycin. For ampicillin, cephalothin, and Colistin marked differences were recorded with respect to O-serogroup. Most O1 strains were resistant to Colistin and sensitive to ampicillin and cephalothin, while most O2 strains were sensitive to Colistin but resistant to ampicillin and cephalothin. Some antibiotic resistant strains carried plasmids but no conjugation experiments were carried out to detect possible R factors.     

Therapeutic efficacy of water-soluble lincomycin-spectinomycin powder against porcine proliferation enteropathy in a European field study

Controlled clinical trials to a standardised protocol were conducted into the effect of a water-soluble antibiotic on proliferative enteropathy and its causative agent (Lawsonia intracellularis) on commercial pig farms at six sites in four European countries. Clinical signs of the disease and L intracellularis-specific polymerase chain reaction (PCR)-positive pigs were detected in pens of six- to 12-week-old pigs (weighing 5 to 55 kg) immediately before each trial. Matched pens of randomised pigs were either left unmedicated (32 to 59 pigs per trial), or medicated orally with 10 mg/kg of a water-soluble combination of lincomycin and spectinomycin powder (21 and 42 mg, respectively, of antibiotic activity per litre) for either seven days (33 to 61 pigs per trial), or 14 days (33 to 61 pigs per trial), delivered via the drinking water. Investigators did not know which pens received which treatment In most of the affected pigs in each trial, diarrhoea due to L intracellularis resolved within three to seven days after the medication began, whereas most unmedicated pigs remained diarrhoeic for at least 10 days. On average the medicated pigs gained more weight than the unmedicated pigs over the 21-day trial period (P=0.01). In two trials, the absence of L intracellularis after the treatment ended was confirmed by the PCR.     

The effects of combinations of selected antibiotics on the growth of Corynebacterium equi

The minimal inhibitory concentrations of penicillin G, ampicillin, gentamicin, erythromycin and rifampicin were determined for nine strains of Corynebacterium equi. The effect of combinations of any two of these antibiotics on the killing of these strains was determined at antibiotic concentrations achievable in horses using recommended drug dosages (ampicillin 4.0 μg/ml, gentamicin 1.0 μg/ml and erythromycin 0.25 μg/ml). Penicillin G was used at 4.0 μg/ml and rifampicin at 0.063 μg/ml. The combinations of gentamicin with erythromycin or rifampicin gave antagonistic effects on killing compared to either drug alone. Combinations of erythromycin with rifampicin or penicillin showed synergistic effects, as did penicillin-gentamicin. All other combinations, and a triple combination of penicillin-rifampicin-erythromycin, showed additive effects only.