Longitudinal effects of enrofloxacin or tulathromycin use in preweaned calves at high risk of bovine respiratory disease on the shedding of antimicrobial-resistant fecal Escherichia coli.

The objective of this study was to longitudinally quantify Escherichia coli resistant to ciprofloxacin and ceftriaxone in calves treated with enrofloxacin or tulathromycin for the control of bovine respiratory disease (BRD). Dairy calves 2 to 3 wk of age not presenting clinical signs of pneumonia and at high risk of developing BRD were randomly enrolled in 1 of 3 groups receiving the following treatments: (1) single label dose of enrofloxacin (ENR); (2) single label dose of tulathromycin (TUL); or (3) no antimicrobial treatment (control, CTL). Fecal samples were collected immediately before administration of treatment and at d 2, 4, 7, 14, 21, 28, 56, and 112 d after beginning treatment. Samples were used for qualification of E. coli using a selective hydrophobic grid membrane filter (HGMF) master grid. The ENR group had a significantly higher proportion of E. coli resistant to ciprofloxacin compared with CTL and TUL at time points 2, 4, and 7. At time point 28, a significantly higher proportion of E. coli resistant to ciprofloxacin was observed only compared with CTL. The TUL group had a significantly higher proportion of E. coli resistant to ciprofloxacin compared with CTL at time points 2, 4, and 7. None of the treatment groups resulted in a significantly higher proportion of E. coli isolates resistant to ceftriaxone. Our study identified that treatment of calves at high risk of developing BRB with either enrofloxacin or tulathromycin resulted in a consistently higher proportion of ciprofloxacin-resistant E. coli in fecal samples.

Calf care personnel on dairy farms and their educational opportunities.

As dairy herd sizes become larger and the organization of the business more complex, targeting communication and education to enhance animal care becomes more difficult. The purpose of this study was to describe selected demographics of calf care employees on large (>500 animals) and small (<501 animals) dairy farms that raise their own calves. Two to 8 individuals per farm involved with calf care, including owners, veterinarians, and calf managers, feeders, and treaters, were interviewed in either English or Spanish. Interviews were conducted in person on 53 dairy farms located in Arizona, Idaho, New York, Oregon, and Washington State. The number of preweaned calves on the farm ranged from 9 to 1,500 (median = 93). A total of 224 individuals were interviewed across 8 job titles. As farm size increased, personnel structure became more complex. Farms with >100 preweaned calves were 15 times more likely to have a calf manager title compared with farms with ≤100 preweaned calves. Eight farms designated the same person as calf manager, treater, and feeder, all with ≤100 preweaned calves. Thirty-two (60%) of the farms had at least 1 full-time calf feeder. Almost 30% of owners and over 40% of veterinarians interviewed were over 50 yr of age, whereas over 40% of the calf managers, feeders, and treaters were under 30 yr of age. Seventy-three percent of feeders and 72% of treaters spoke Spanish at home. For languages in which interviewees were comfortable speaking, more than 30% of owners and 33% of veterinarians were comfortable communicating in Spanish. For calf care employees, 60% of calf managers, 42% of feeders, and 38% of treaters were bilingual (English and Spanish), but most (72%) preferred to be interviewed in Spanish. The level of education varied by job title for those interviewed, but most of the calf care team had high school or less education. However, some diversity was observed in educational background within job title with almost 38% of the calf managers having at least some college education. The majority of feeders (88%) and treaters (83%) reported being trained by another employee and 66 and 58%, respectively, had not received any continuing education in the previous year. With the amount of diversity seen on these farms, understanding employees' educational backgrounds, language, and generational differences may be valuable when developing training for new procedures for animal health or other aspects of animal care.

Effect of heifer-raising practices on E. coli antimicrobial resistance and Salmonella prevalence in heifer raisers.

Although cattle movement and commingling play an important role in the inter-herd transmission of pathogens, little is known about the effect of commingling of heifers at raising operations. The objective of this study was to compare the resistance of E. coli and prevalence of Salmonella from pooled faecal pats of heifers raised off-farm at multi-source raisers (MULTI) that raised heifers from at least two farms compared with on-farm raisers (HOME), with heifers from only that farm. MULTI faecal pat samples were collected from pens with animals that had arrived at the farm within the previous 2 months (AP) and from animals that would be departing the heifer raiser in 2-3 months (DP). Corresponding age sampling was conducted at HOME raisers. Odds of ampicillin resistance were 3·0 times greater in E. coli collected from MULTI compared to HOME raisers. E. coli from AP pens had significantly (P < 0·05) higher odds of resistance to ampicillin, neomycin, streptomycin, and tetracycline compared to DP pens. Salmonella recovery was not significantly different between heifer-raising systems (P = 0·3). Heifer-raising system did not have a major overall impact on selection of resistant E. coli, which was strongly affected by the age of the animals sampled.

Multiresidue screening of milk withheld for sale at dairy farms in central New York State.

Many of the drugs commonly used in lactating dairy cows result in residues in the milk, prohibiting its sale for human consumption. Milk withheld for sale because of drug treatment or from cows with high somatic cell counts is commonly called "waste milk." One-third of dairy farms in the United States use waste milk to feed preweaned dairy calves. Limited information is currently available on the effect of this practice on the selection and dissemination of antibiotic-resistant bacteria. Pooled waste milk samples were collected from 34 dairy farms in central New York State with the objective of detecting the presence and quantity of drug residues in these samples. Samples were collected and refrigerated using ice packs and then stored at 4°C upon arrival at the Cornell laboratory (Ithaca, NY). Screening for ß-lactam, tetracycline, and sulfonamide residues in the milk was performed using commercial enzyme-linked receptor-binding assay (SNAP) tests (Idexx Laboratories Inc., Westbrook, ME). Samples with a positive SNAP test were selected for screening using a multiresidue liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The SNAP tests revealed that 75, 14.3, and 7.1% of waste milk samples (n=34) contained ß-lactam, tetracycline, and sulfamethazine residues, respectively. Of the samples sent for LC-MS/MS (n=28), half had detectable quantities of drug residues. The most prevalent drugs detected by LC-MS/MS were ceftiofur (39.2%; mean ± SE concentration=0.151 ± 0.042 µg/mL), penicillin G (14.2%; mean ± SE concentration=0.008 ± 0.001 µg/mL), and ampicillin (7.1%; mean ± SE concentration=0.472 ± 0.43 µg/mL). In addition, one sample had detectable concentrations of oxytetracycline and one sample had detectable concentrations of sulfadimethoxine. These results provide insight on drug residues present in waste milk from select farm in upstate New York, and additionally indicate the need for additional studies targeting on-farm treatments that could degrade drug residues present in waste milk and reduce the potential effects on the biosphere from the disposal and use of waste milk as a feed source.

Effect of preweaned dairy calf housing system on antimicrobial resistance in commensal Escherichia coli.

Group housing of preweaned dairy calves is a growing practice in the United States. The objective of this practice is to increase the average daily gain of calves in a healthy and humane environment while reducing labor requirements. However, feeding protocols, commingling of calves, and occurrence of disease in different calf-housing systems may affect the prevalence of antimicrobial drug-resistant bacteria. This study evaluated the effect of a group pen-housing system and individual pen-housing system on antimicrobial resistance trends in fecal Escherichia coli of preweaned dairy calves and on the prevalence of environmental Salmonella. Twelve farms from central New York participated in the study: 6 farms using an individual pen-housing system (IP), and 6 farms using a group pen-housing system (GP). A maximum of 3 fecal E. coli isolates per calf was tested for susceptibility to 12 antimicrobial drugs using a Kirby-Bauer disk diffusion assay. Calves in GP had a significantly higher proportion of E. coli resistant to ciprofloxacin and nalidixic acid, whereas calves in IP had a significantly higher proportion of E. coli resistant to ampicillin, ceftiofur, gentamycin, streptomycin, and tetracycline. Calf-housing system had an effect on resistance to individual antimicrobial drugs in E. coli, but no clear-cut advantage to either system was noted with regard to overall resistance frequency. No outstanding difference in the richness and diversity of resistant phenotypes was observed between the 2 calf-housing systems.

Effect of on-farm use of antimicrobial drugs on resistance in fecal Escherichia coli of preweaned dairy calves.

Respiratory disease and diarrhea are the 2 most common diseases that result in the use of antimicrobial drugs in preweaned calves. Because the use of drugs in food animals, including dairy calves, has the potential for generating cross-resistance to drugs used in human medicine, it is vital to propose farm practices that foster the judicious use of antimicrobials while assuring animal health and productivity. The objective of this study was to use dairy farm calf treatment records to identify antimicrobial drug treatments in calves and to evaluate their effects on the prevalence of antimicrobial-resistant Escherichia coli from rectal swabs of preweaned dairy calves. Eight farms from central New York participated in the study, 3 farms using individual pen housing management and 5 farms using group pen housing management. Eligible study farms could not add antimicrobial drugs to the milk fed to preweaned calves and were required to have farm records documenting antimicrobial drug treatment of calves from birth to weaning. Three fecal E. coli isolates per calf were tested for susceptibility to 12 antimicrobial drugs using a Kirby-Bauer disk diffusion assay. A total of 473 calves were sampled, from which 1,423 commensal E. coli isolates were tested. Of the 9 antimicrobial drugs used on study farms, only enrofloxacin was significantly associated with reduced antimicrobial susceptibility of E. coli isolates, although treatment with ceftiofur was associated with reduced susceptibility to ceftriaxone. The median numbers of days from treatment with ceftiofur and enrofloxacin to rectal swab sampling of calves were 16 d (range: 1-39) and 12 d (range: 6-44), respectively. At the isolate level, treatment with enrofloxacin resulted in odds ratios of 2 [95% confidence interval (CI): 1-4] and 3 (95% CI: 2-6), respectively, for isolation of nonsusceptible E. coli to nalidixic acid and ciprofloxacin compared with calves not treated with enrofloxacin. Treatment with ceftiofur resulted in an odds ratio of 3 (95% CI: 0.9-12) for isolation of nonsusceptible E. coli to ceftriaxone compared with calves not treated with ceftiofur. Treatment with enrofloxacin resulted in selection of isolates that presented phenotypic resistance to both ciprofloxacin and ceftriaxone. Treatment with ceftiofur resulted in a higher prevalence of isolates resistant to ≥3 antimicrobial drugs (97%) compared with no treatment with ceftiofur (73%). These findings reinforce the necessity for continued implementation of practices at the dairy farm that support the sustainable and judicious use of antimicrobial drugs in dairy calves.

Genotypic antimicrobial resistance characterization of E. coli from dairy calves at high risk of respiratory disease administered enrofloxacin or tulathromycin.

The objective of this study was to evaluate the longitudinal effect of enrofloxacin or tulathromycin use in calves at high risk of bovine respiratory disease (BRD) on antimicrobial resistance genes and mutation in quinolone resistance-determining regions (QRDR) in fecal E. coli. Calves at high risk of developing BRD were randomly enrolled in one of three groups receiving: (1) enrofloxacin (ENR; n = 22); (2) tulathromycin (TUL; n = 24); or (3) no treatment (CTL; n = 21). Fecal samples were collected at enrollment and at 7, 28, and 56 days after beginning treatment, cultured for Escherichia coli (EC) and DNA extracted. Isolates were screened for cephalosporin, quinolone and tetracycline resistance genes using PCR. QRDR screening was conducted using Sanger sequencing. The only resistance genes detected were aac(6')Ib-cr (n = 13), bla-CTX-M (n = 51), bla-TEM (n = 117), tetA (n = 142) and tetB (n = 101). A significantly higher detection of gyrA mutated at position 248 at time points 7 (OR = 11.5; P value = 0.03) and 28 (OR = 9.0; P value = 0.05) was observed in the ENR group when compared to calves in the control group. Our findings support a better understanding of the potential impacts from the use of enrofloxacin in calves on the selection and persistence of resistance.

Cyproterone acetate reduced antler growth in surgically castrated fallow deer.

We studied the role of androgens in antler growth. In particular, we investigated whether the onset of antler regrowth is triggered by a short-term pulse of testosterone and if low levels of androgens are required for antler growth. The study was conducted on 12 surgically castrated fallow deer bucks (Dama dama) aged approximately 27 months. Six animals (CA group) were given the antiandrogen, cyproterone acetate (CA, 1000 mg/treatment); the others were given vehicle solution only (control). Before each CA treatment, blood was sampled and analysed for testosterone, androstenedione, IGF-1, cortisol, FSH, and LH. CA treatment and blood sampling were performed 2 days before castration, on the day of castration and afterwards at 2-day intervals until day 22. Subsequently, CA treatment and blood sampling continued at weekly intervals until day 270. All animals cast their antlers, followed by antler regrowth in all control bucks, but in only four of the six CA-treated castrates. Plasma testosterone concentrations were low in all animals (between 0.01 and 0.20 ng/ml), but were significantly (P<0001) greater in the controls. In both groups, a temporary increase in testosterone values was recorded around the time of antler regrowth, the peak being significantly (P<0.01) higher in the controls. Androstenedione showed a similar pattern as testosterone. Plasma IGF-1 concentrations increased sharply during the antler growth spurt and did not differ significantly between the two groups throughout the study period. Cortisol concentrations were greater in controls than in the CA group. However, no link with the antler cycle was apparent. FSH and LH concentrations were higher in the controls for most of the study. Antlers produced by the control bucks were significantly larger than those in the CA group (P<0.03). For antler length, testosterone, androstenedione and IGF-1, areas under the curve (AUC) were calculated over the period of antler growth. For the pooled deer (n=12) significant correlations existed between AUCs of antler length and testosterone, but not for antler length and IGF-1. Also, a trend for a positive correlation between AUCs of antler length and androstenedione was noted. It is concluded that a plasma androgen concentration at least above a minimal threshold level is a necessary prerequisite for normal antler regrowth in fallow deer, and that this androgen effect is not mediated via circulating IGF-1. The biological role of low levels of androgens may be to sensitize antler cells to the stimulating effect of IGF.

The natural history of endemic trachoma: a longitudinal study.

A longitudinal study of trachoma was conducted among 100 members of nine families living in a hyperendemic area of Tanzania. Family members were examined for trachoma every three months for one year and conjunctival specimens were collected for antigen detection, which was performed either by direct fluorescent antibody cytologic analysis or enzyme immunoassay. The serovar specificity of tear antibodies was determined. Overall, young children tended to form a core of those with persistent, often severe, disease who consistently shed Chlamydia. These children are a potential source of infection in their family. Chlamydia could be identified early in the course of presumed recently acquired infections, but not later in resolving infections. This temporal change may account for the discrepancies between demonstrable organisms and clinical disease seen in cross-sectional studies. Several children were identified who did not develop trachoma despite having Chlamydia identified in conjunctival scrapings. Their ability to resist infection may offer clues for vaccine development. The study of serovar specificity is consistent with the intrafamily transmission of trachoma, but was confounded by the large family size and the potential for separate transmission units to occur within large extended families. These observations give further understanding of the natural history and kinetics of the transmission of trachoma that should be of use in developing and evaluating intervention studies.

Lidocaine hydrochloride versus lidocaine bicarbonate for epidural anesthesia in outpatients undergoing arthroscopic surgery.

In a randomized, double-blind study, 24 patients undergoing outpatient arthroscopic knee surgery were divided into two groups. Group 1 received 2% lidocaine hydrochloride; group 2 received pH-adjusted 1.73% lidocaine made by adding 1 ml of NaHCO3 44.6 meq/L to 10 ml of 2% lidocaine hydrochloride. Epidural anesthesia was administered in the sitting position. Group 1 consisted of 12 males; group 2 consisted of 6 males and 6 females (p less than 0.01). Statistical analysis using the unpaired Student's t-test and the Mann-Whitney test found no significant differences between the two groups regarding time of onset of analgesia, degree of spread of analgesia, time to maximum motor blockade, degree of motor blockade, length of surgical procedure, total anesthesia time, regression of anesthesia, dosage of lidocaine used, and serum lidocaine levels. Intraoperative conditions were satisfactory in all cases. Postoperatively, all patients reported having experienced a satisfactory anesthetic without any complications. The authors conclude that epidural anesthesia is a satisfactory technique for outpatient arthroscopic surgery. There appears to be no advantage to adding bicarbonate to lidocaine anesthetic solutions for use in epidural anesthesia.

Healthier work environments through action research.

A team of nurses and a university-based nurse researcher describe a nursing theory-based action research plan to promote a healthier work environment. The process combines research and practice to achieve desired outcomes within an acute-care setting.

Subtype analysis of Salmonella isolated from subclinically infected dairy cattle and dairy farm environments reveals the presence of both human- and bovine-associated subtypes.

While it is well established that clinically ill livestock represent a reservoir of Salmonella, the importance of subclinical shedders as sources of human salmonellosis is less well defined. The aims of this study were to assess the subtype diversity of Salmonella in healthy dairy cattle and farm environments and to compare the subtypes isolated from these sources with the Salmonella subtypes associated with clinical human cases in the same geographic area. A total of 1349 Salmonella isolates from subclinical dairy cattle and farm environments (46 farms) were initially characterized by traditional or molecular serotyping and tested for antimicrobial susceptibility. A set of 381 representative isolates was selected for further characterization by pulsed-field gel electrophoresis (PFGE); these isolates represented unique combinations of sampling date, serovar, antimicrobial resistance pattern, farm of origin, and source, to avoid overrepresentation of subtypes that were re-isolated from a given source. These 381 isolates represented 26 Salmonella serovars; the most common serovars were Cerro [(38.8%, 148/381) isolated from 21 farms], Kentucky [16.3%; 10 farms], Typhimurium [9.4%; 7 farms], Newport [7.6%; 8 farms], and Anatum [6.3%; 6 farms]. Among the 381 isolates, 90 (23.6%) were resistant to between 1 and 11 antimicrobial agents, representing 50 different antimicrobial resistance patterns. Overall, 61 XbaI-PFGE types were detected among these 381 isolates, indicating considerable Salmonella diversity on dairy farms. Fourteen PFGE types, representing 12 serovars, exactly matched PFGE types from human isolates, suggesting that subclinically infected dairy cattle could be sources of human disease-associated Salmonella.

Salmonella Cerro isolated over the past twenty years from various sources in the US represent a single predominant pulsed-field gel electrophoresis type.

Salmonella Cerro prevalence in US dairy cattle has increased significantly during the past decade. Comparison of 237 Salmonella isolates collected from various human and animal sources between 1986 and 2009 using pulsed-field gel electrophoresis, antimicrobial resistance typing, and spvA screening, showed very limited genetic diversity, indicating clonality of this serotype. Improved subtyping methods are clearly needed to analyze the potential emergence of this serotype. Our results thus emphasize the critical importance of population-based pathogen surveillance for the detection and characterization of potentially emerging pathogens, and caution to critically evaluate the adequacy of diagnostic tests for a given study population and diagnostic application.

Nuclease activity in cell-free amino acid-incorporating systems from chicken liver.

1. Comparative studies of the polyuridylic acid-directed phenylalanine-incorporating activity of cell-free systems derived from rat and chicken livers demonstrated markedly lower activity in the chicken liver system. 2. The chicken liver cell sap contained the factor(s) responsible for this lower activity. Ribosomes from chicken and rat performed equally well in the presence of rat liver cell sap. Chicken liver cell sap, when mixed with rat liver cell sap, caused an inhibition of incorporation of phenylalanine into acid-insoluble material. 3. Though ribosomal preparations and cell sap from both rat and chicken liver degraded polyuridylic acid to some extent, the chicken liver cell sap contained the largest amount of activity. 4. Rat liver cell sap inhibited the nuclease activities of ribosomal preparations, but no such nuclease inhibition could be demonstrated with chicken liver cell sap.

Increased echogenicity of the spleen in benign and malignant disease.

Infiltration of the spleen in hematopoietic malignancy can produce diffusely increased parenchymal echo return on gray scale ultrasonography. In 13 patients with splenomegaly and an increased splenic echo pattern, nine had diagnoses of hematopoietic malignancy. Contrary to previous reports describing low-level echo return and increased anechoic conditions with infiltrating malignancy of the spleen, the patients in this report show that increased splenic echogenicity can be associated with malignant involvement.

Propofol reduces prolonged outpatient PACU stay. An analysis according to surgical procedure.

This study compared the effects of propofol anesthesia and nonpropofol general anesthetics on duration of stay in the postanesthesia care unit (PACU) for prolonged drowsiness or nausea and vomiting following various surgical procedures. A group of 512 patients undergoing general anesthesia for a variety of outpatient surgical procedures over a 6-month period received general anesthesia with nitrous oxide, with or without propofol. Data collected from PACU records included type of surgical procedure and duration in the PACU of more than 2 hours owing to drowsiness or nausea and vomiting. Overall, patients who received propofol with nitrous oxide experienced less frequent drowsiness, nausea, or vomiting compared with patients who received nonpropofol anesthetic agents (drowsiness 12% vs 31%; nausea/vomiting 3% vs 25%). For patients undergoing gynecologic surgery, propofol anesthesia yielded an 8% incidence of prolonged PACU stay, compared with 41% for nonpropofol techniques. Similar results occurred for orthopedic surgery (15% vs 35%); for ear, nose, or throat procedures (30% vs 75%); and for ophthalmic surgery (18% vs 71%), but not for oral surgery (44% vs 64%). Most same-day surgery patients benefit from administration of propofol for induction and maintenance of anesthesia. Advantages include a decreased likelihood of a prolonged stay in the PACU as a result of drowsiness or nausea and vomiting.

Longitudinal study of the microbiology of endemic trachoma.

A longitudinal study of trachoma in 100 members of nine Tanzanian families was conducted to assess the sources of variation in the laboratory identification of trachoma and the changes that might occur over time. Multiple conjunctival swabs were collected every 3 months for 1 year and examined by direct fluorescent-antibody cytology (DFA), enzyme immunoassay, or microimmunofluorescence serology for tear antichlamydial antibodies. DFA specimens collected 5 min apart had a discordance rate of 10% and this is attributable to sampling variation. DFA specimens collected 2 days or more apart show a 25% discordance rate. This suggests a biologic variation in shedding in addition to sampling variation. Good correlation existed between the DFA and the enzyme immunoassay. Tear serology was quite specific in predicting the presence of clinical disease and correlated with the other two antigen detection tests, although it does not seem to offer any practical advantages. These studies indicate that there is considerable variation in the shedding of chlamydia by people living in trachoma-endemic areas.