Mannheimia haemolytica in feedlot cattle: prevalence of recovery and associations with antimicrobial use, resistance, and health outcomes.

BACKGROUND: Mannheimia haemolytica is an important etiological agent in bovine respiratory disease. OBJECTIVES: Explore risk factors for recovery of susceptible and resistant M. haemolytica in feedlot cattle and explore associations with health outcomes. ANIMALS: Cattle (n = 5,498) from 4 feedlots sampled at arrival and later in feeding period. METHODS: Susceptibility of M. haemolytica isolates tested for 21 antimicrobials. Records of antimicrobial use and health events analyzed using multivariable regression. RESULTS: M. haemolytica recovered from 29% of cattle (1,596/5,498), 13.1% at arrival (95% CI, 12.3-14.1%), and 19.8% at second sampling (95% CI, 18.7-20.9%). Nearly half of study cattle received antimicrobial drugs (AMDs) parenterally, mostly as metaphylactic treatment at arrival. Individual parenteral AMD exposures were associated with decreased recovery of M. haemolytica (OR, 0.2; 95% CI, 0.02-1.2), whereas exposure in penmates was associated with increased recovery (OR, 1.5; 95% CI, 1.05-2.2). Most isolates were pan-susceptible (87.8%; 95% CI, 87.0-89.4%). AMD exposures were not associated with resistance to any single drug. Multiply-resistant isolates were rare (5.9%; 95% CI, 5.1-6.9%), but AMD exposures in pen mates were associated with increased odds of recovering multiply-resistant M. haemolytica (OR, 23.9; 95% CI, 8.4-68.3). Cattle positive for M. haemolytica on arrival were more likely to become ill within 10 days (OR, 1.7; 95% CI, 1.1-2.4). CONCLUSIONS AND CLINICAL IMPORTANCE: Resistance generally was rare in M. haemolytica. Antimicrobial drug exposures in penmates increased the risk of isolating susceptible and multiply-resistant M. haemolytica, a finding that could be explained by contagious spread.

Effects of wheat or corn distillers dried grains with solubles on feedlot performance, fecal shedding, and persistence of Escherichia coli O157:H7.

Distillers dried grains with solubles (DDGS) are a coproduct of the ethanol industry and are often used as a replacement for grain in livestock production. Feeding corn DDGS to cattle has been linked to increased fecal shedding of Escherichia coli O157:H7, although in Canada, DDGS are often produced from wheat. This study assessed the effects of including 22.5% wheat or corn DDGS (DM basis) into barley-based diets on performance, carcass characteristics, animal health, and fecal E. coli O157:H7 shedding of commercial feedlot cattle. Cattle (n = 6,817) were randomly allocated to 10 pens per treatment group: WDDGS (diets including 22.5% wheat DDGS), CDDGS (diets including 22.5% corn DDGS), or CTRL (barley substituted for DDGS). Freshly voided fecal pats (n = 588) were collected and pooled monthly for fecal pH measurement and screened for naturally occurring E. coli O157:H7 by immunomagnetic separation (IMS) and direct plating (DP). Hide swabs (n = 367) were collected from randomly selected cattle from each pen before slaughter. Pen-floor fecal samples (n = 18) were collected from treatment groups at entry to the feedlot (<14 d on the finishing diet) and after adapting to the finishing diet for ≥ 14 d, inoculated (10(9) cfu of a 5 strain naldixic acid-resistant E. coli O157:H7 mixture), incubated (20°C) and evaluated weekly (IMS and DP) to assess fecal E. coli O157:H7 persistence. The WDDGS group had 3.0% poorer ADG (P = 0.007), 5.3% poorer G:F (P < 0.001), and a decreased proportion of Canada Quality Grade AAA carcasses (P = 0.022) compared with CTRL cattle. The CDDGS group had a similar ADG (P = 0.06), a decreased proportion of Canada Yield Grade (YG) 1 (P < 0.001), and greater proportions of Canada YG 2 (P = 0.003) and YG 3 (P < 0.001) carcasses compared with the CTRL group. There were no differences among groups in any of the animal health parameters assessed. Inclusion of DDGS in cattle finishing diets had no effect on fecal shedding (P = 0.650) or persistence (P = 0.953) of E. coli O157:H7. However, feces from cattle on starter diets <14 d had longer persistence of E. coli O157:H7 (week) than cattle on finishing diets ≥ 14 d (P < 0.003). Inclusion of DDGS in feedlot diets depends on commodity pricing relative to that of barley and for WDDGS must also include the risk of feedlot performance and carcass grading disadvantages. Feeding cattle barley based-diets with 22.5% corn or wheat DDGS did not affect fecal shedding of E. coli O157:H7.

The prevalence of methicillin-resistant Staphylococcus aureus colonization in feedlot cattle.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen and recent evidence has implicated food animals in the epidemiology of human infections in some regions. While the role of food in MRSA transmission and human health relevance are unclear, MRSA can be found in retail meat products internationally, including beef, yet there has been minimal investigation of MRSA in beef cattle. This study involved screening feedlot cattle for nasal and gastrointestinal colonization with MRSA shortly before the time of slaughter. Methicillin-resistant S. aureus was not isolated from any of 491 nasal swabs and 488 faecal samples. This finding is in contrast to studies that have isolated MRSA from retail beef in Canada, performed in the same laboratory using comparable culture techniques. The reason for this discrepancy is unclear but it demonstrates that further study of MRSA in livestock as well as slaughter, processing and retail environments is needed to elucidate the epidemiology of MRSA contamination of meat.

Genetic characterization and antimicrobial susceptibility of Mannheimia haemolytica isolated from the nasopharynx of feedlot cattle.

A surveillance study was undertaken to examine the population dynamics and antimicrobial resistance of Mannheimia haemolytica isolated from feedlot cattle. A total of 416 isolates were collected from the nasopharynx either upon entry or exit from two feedlots in southern Alberta, Canada. Isolates were serotyped, characterized by pulsed-field gel electrophoresis and tested for susceptibility to ten antimicrobial agents via disk diffusion. Resistant isolates were screened by PCR for select antimicrobial-resistance gene determinants. Isolates were highly diverse, with 335 unique pulsed-field profiles identified among 147 strongly related clusters (similarity ≥ 85%). Clonal spread of isolates throughout the feedlots was limited and no clear association was found between genetic relatedness of M. haemolytica and sampling event (entry or exit). Pulsed-field profiles sharing a common serotype and resistance phenotype tended to cluster together. The majority of isolates were identified as serotype 2 (74.5%) although both serotype 1 (11.9%) and 6 (12.7%) were detected. Only 9.54% of isolates exhibited antimicrobial resistance. Resistance to oxytetracycline was most prevalent (n=16), followed by ampicillin (n=10), and amoxicillin/clavulanic acid (n=7). Multi-drug resistance was observed in five isolates. The tetH gene was detected in all but two oxytetracycline resistant isolates. Other detectable resistance determinates included ermX and bla(ROB-1). In the two feedlots examined, M. haemolytica exhibited considerable genetic diversity and limited resistance to common veterinary antibiotics. Garnering further information on the linkage between genotype and phenotype should contribute toward a better understanding of the pathogenesis and dissemination of M. haemolytica in feedlots.

Detection of Coxiella burnetii in placenta and abortion samples from British ruminants using real-time PCR.

A real-time PCR was developed to detect Coxiella burnetii (the cause of Q fever) in ruminant placentas and aborted fetuses. Primer and probe sets previously developed for human tissue studies were used to target the insertion sequence IS1111 gene for C burnetii. The assay was highly sensitive, with a limit of detection of 10 copies of template, theoretically equating to a single bacterium, and did not cross-react with a panel of other bacteria. To determine sensitivity on field samples submitted for the diagnosis of abortion, results using the IS1111 PCR assay were compared with a com1 PCR assay. When applied to ruminant abortion material, including placental cotyledons and fetal samples, the IS1111 and com1 assays yielded positive results in 23 (25 per cent) of 93 and 19 (20 per cent) of 93 samples, respectively. One infected goat herd was monitored for 31 months: 57 (92 per cent) of 62 placental cotyledon samples from aborting and non-aborting goats, and 10 (30 per cent) of 33 fetal samples were positive by the IS1111 PCR assay.

Development of a real time PCR for the detection of Taylorella equigenitalis directly from genital swabs and discrimination from Taylorella asinigenitalis.

A discriminatory real time PCR for the detection of Taylorella equigenitalis, the causative agent of contagious equine metritis (CEM), and the related species T. asinigenitalis was developed for the direct examination of genital swabs. The 112bp amplicons produced from the two species were discriminated from each other using TaqMan probes labelled with different fluorophores. The TaqMan PCR was shown to be specific for the 16S ribosomal DNA of the two species of taylorella and did not cross-hybridise with the 16S ribosomal DNA of other bacteria tested. Direct amplification from genital swabs was shown to be equally sensitive to that of culture methods. Prevalence in a sample set from The Netherlands was shown to be equivalent to that demonstrated by culture. A companion real time PCR that amplified a fragment of the 16S rDNA gene of equine commensal bacteria was developed to ensure bacterial DNA was extracted from swab material supplied for testing. The use of a rapid and reliable real time PCR for the organism causing CEM should aid the control of this disease.

The partial overdenture in management of anterior apertognathia: a clinical report.

A patient with anterior apertognathia presented with an unserviceable maxillary removable partial denture. The unique pattern of partial edentulism was treated with a partial overdenture restoration of the bar attachment design. The final prosthesis was stable, well retained, and esthetic, serving as a conservative alternative to a surgical-orthognathic plan of treatment.

Background and principles of an African American targeted national anti-drug campaign.

This article provides a review of key African American community values drawn from the literature. Central to this article is how these values can be incorporated into anti-drug messages and materials targeted to African Americans as part of a national five-year campaign being implemented by the White House Office of National Drug Control Policy and the Partnership for a Drug-Free America. The campaign is the first national campaign to base messages on behavioral science research and theories and subsequently uses research about targeted audiences to design prevention messages that are culturally relevant. Specific implications for the format and content of messages directed to African Americans are discussed.

Efficacy response of inhaled beclomethasone dipropionate in asthma is proportional to dose and is improved by formulation with a new propellant.

BACKGROUND: This study tested the hypothesis that there would be improved asthma control with increasing doses of beclomethasone dipropionate (BDP) formulated in hydrofluoroalkane-134a (HFA-BDP) and the standard chlorofluorocarbon propellants (CFC-BDP). Because HFA-BDP has improved lung deposition compared with CFC-BDP, this study also tested the hypothesis that HFA-BDP would provide more effective control of asthma than CFC-BDP. METHODS: In this multicenter, randomized, parallel-group blinded study, asthmatic subjects who had deterioration in asthma control after discontinuation of inhaled corticosteroids were randomized to receive one of 6 possible treatments: 100 microg/d, 400 microg/d, or 800 microg/d of HFA-BDP or 100 microg/d, 400 microg/d, or 800 microg/d of CFC-BDP for 6 weeks. Changes in spirometry, daytime asthma symptom and nighttime asthma-related sleep disturbance scores, morning and evening peak expiratory flows, and daily use of inhaled beta-agonist for symptom control on diary cards were assessed over 6 weeks of treatment. RESULTS: Three hundred twenty-three patients were randomized to the 6 treatment groups, which had similar demographics and baseline lung function. There were significantly larger changes from baseline at week 6 in FEV(1) percent predicted with increasing doses of both HFA-BDP and CFC-BDP. The FEV(1) percent predicted dose-response curve for HFA-BDP was shifted to the left compared with the dose-response curve for CFC-BDP. By using the Finney bioassay method, it was calculated that 2.6 times as much CFC-BDP would be required to achieve the same improvement in FEV(1) percent predicted as HFA-BDP (95% confidence interval, 1.1-11.6). All treatment groups except the 100 microg/d CFC-BDP group tolerated study drug well. Ten (17%) of 59 patients in this group reported an acute asthma episode, increased asthma symptoms (6 of the 8 reports of increased asthma symptoms were classified as severe), or both, and 8 patients withdrew from the study (3 for adverse events related to asthma). CONCLUSIONS: Increasing doses of inhaled corticosteroids lead to improved lung function and asthma control. Moreover, the reformulation of BDP in HFA enables effective asthma control at much lower doses than CFC-BDP.

Diurnal variation in 5-HT1B autoreceptor function in the anterior hypothalamus in vivo: effect of chronic antidepressant drug treatment.

1. Intracerebral microdialysis was used to examine the function of the terminal 5-hydroxytryptamine (5-HT) autoreceptor in the anterior hypothalamus of anaesthetized rats at two points in the light phase of the light-dark cycle. 2. Infusion of the 5-HT1A/1B agonist 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridyl)-1H-indole (RU24969) 0.1, 1.0 and 10 microM through the microdialysis probe led to a concentration-dependent decrease (49, 56 and 65% respectively) in 5-HT output. The effect of RU24969 (1 and 5 microM) was prevented by concurrent infusion of methiothepin (1 and 10 microM) into the anterior hypothalamus via the microdialysis probe. Infusion of methiothepin alone (1.0 and 10 microM) increased (15 and 142% respectively) 5-HT output. 3. Infusion of RU24969 (5 microM) through the probe at mid-light and end-light resulted in a quantitatively greater decrease in 5-HT output at end-light compared with mid-light. 4. Following treatment with either paroxetine hydrochloride (10 mg kg(-1) i.p.) or desipramine hydrochloride (10 mg kg)(-1) i.p.) for 21 days the function of the terminal 5-HT1B autoreceptor was more markedly attenuated at end-light. 5. The data show that, as defined by the response to RU24969, the function of the 5-HT1B receptors that control 5-HT output in the anterior hypothalamus is attenuated following chronic desipramine or paroxetine treatment in a time-of-day-dependent manner.

The immediate provisional restoration: a review of clinical techniques.

For each patient who requires removal of anterior teeth, there are a multitude of treatment considerations. Cosmetic demands, functional needs, treatment sequencing, timeliness, and affordability are some primary concerns that must be addressed on an individual basis. A patient will generally want a cosmetic and functional prosthesis at the earliest possible opportunity. Providing the most appropriate interim prosthesis for a given patient is both challenging and rewarding. The numerous clinical techniques for immediate interim tooth replacement are reviewed, and previously unreported methods are presented to assist the clinician in the selection of interim prosthesis design.

Coherent Doppler lidar measurements of winds in the weak signal regime.

In the weak signal regime coherent Doppler lidar velocity estimates are characterized by a localized distribution around the true mean velocity and a uniform distribution of random outliers over the velocity search space. The performance of velocity estimators is defined by the standard deviation of the good estimates around the true mean velocity and the fraction of random outliers. The quality of velocity estimates is improved with pulse accumulation. The performance of velocity estimates from two different coherent Doppler lidars in the weak signal regime is compared with the predictions of computer simulations for pulse accumulation from 1 to 100 pulses.

Selective use of gingival-toned ceramics: case reports.

Use of periodontal surgical procedures should generally be considered, prior to prosthodontic treatment, for ridge augmentation and correction of minor soft tissue deficiencies. However, in certain instances surgery may be contraindicated or undesirable. An adequate functional and cosmetic result can often be achieved by incorporating pink ceramic material in the patient's fixed prosthesis. Five case reports are reviewed to demonstrate some appropriate uses of this material.

Opposing roles for 5-HT1B and 5-HT3 receptors in the control of 5-HT release in rat hippocampus in vivo.

1. Intracerebral microdialysis was used to determine whether 5-hydroxytryptamine (5-HT) release in the ventral hippocampus of rats anaesthetized with chloral hydrate was modulated by 5-HT3 receptors. 2. It was confirmed that 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU 24969), a selective 5-HT1B receptor agonist, decreased 5-HT release in a dose- and concentration-related manner when administered i.p. (1 and 5 mg kg-1) or via the dialysis probe (0.1 and 1 microM) respectively. The effect of RU 24969 infusion (1 microM) was attenuated by concurrent infusion of metitepine (10 microM) into the hippocampus. 3. When infused into the hippocampus for 15 min, the selective 5-HT3 receptor agonist, 2-methyl-5-hydroxytryptamine (2-methyl-5-HT; 0.1- 10 microM) increased dialysate 5-HT levels in a concentration-related manner; an effect which was abolished by concurrent infusion of 3-tropanyl-3,5-dichlorobenzoate (1 microM, MDL 72222), a selective 5-HT3 antagonist. 4. MDL 72222 had no effects on hippocampal 5-HT release when administered via the dialysis probe (1 or 10 microM). 5. The data show that 5-HT3 and 5-HT1B receptors have opposing roles in the control of 5-HT release in the hippocampus, with 5-HT3 receptors facilitating and 5-HT1B receptors inhibiting 5-HT efflux, respectively. They also indicate that the facilitatory 5-HT3 receptors are not tonically activated.

Sequencing platinum foil matrix removal in postceramic soldering of the collarless veneered retainer.

Postceramic soldering of collarless veneered retainers in which the porcelain margins were formed with a platinum foil matrix technique was investigated. The purpose of the study was to determine if removing the platinum foil matrix before or after indexing and soldering procedures would affect the porcelain margin integrity in fixed partial dentures. Prostheses were fabricated on a nickel-chromium laboratory model using both sequences. Six test cycles were performed. Each cycle included one soldering with matrix support and one without the matrix, for a total of 12 solderings. The fixed partial dentures were compared for degree of marginal seating with a measuring microscope and for configuration changes at the porcelain margins with scanning electron micrographs. In the microscopic analysis of marginal closure, soldering without foil matrix was statistically equal to soldering with foil in place. Removal of the platinum foil matrices prior to indexing provided for no further seating of the metal ceramic retainers. Evaluation by scanning electron microscopy demonstrated distinct configuration changes in the porcelain margins for the specimens soldered without matrix support.

Clinical and humoral effects of beta-blockade with ICI 118,551 in the general neurotic syndrome.

Fifty-six patients satisfying the diagnostic criteria for the general neurotic syndrome, a mixed anxiety-depressive disorder, were randomly allocated to treatment with a selective ß( 2)-blocking drug, ICI 118,551, in a dose of 50 mg tds, or placebo for 4 weeks after a 2-week placebo run-in period. Ratings of anxiety using the Hamilton anxiety rating scale and patient self-assessments in 46 evaluable patients showed no significant difference in the outcome of active drug and placebo groups, and also no significant improvement over time during the study. This unusual finding supports the impression of the general neurotic syndrome as a severe form of neurotic disorder which shows little evidence of placebo response. Diastolic blood pressure was increased and heart rate reduced after 2 weeks on ICI 118,551, and plasma levels of noradrenaline and adrenaline showed no evidence of an expected decrease with active drug; on the contrary the data showed some evidence of increased catecholamine levels. The results suggest that selective ß-blockade has little part to play in the treatment of anxiety and that on repeated dosage the effects of selective blockade are attenuated or reversed.

Breeding site fidelity in willow ptarmigan: the influence of previous reproductive success and familiarity with partner and territory.

Breeding site fidelity is high in willow ptarmigan: only 9% of males and 31% of females switched territories between years. Unpaired males were more likely to switch territories than paired males. For paired males, survival of their previous partner and reproductive success in year x did not influence probability of switching in year x+1. A female was more likely to switch territories if her previous partner disappeared. If her partner returned, she had a higher probability of switching if she did not produce chicks the previous year. Most hens moved to the territories of older males, although hens paired with unfamiliar older males did not have higher reproductive success than those paired with yearlings. Individuals that paired with their previous partner laid earlier and produced heavier chicks than those paired with unfamiliar partners. Excluding birds paired with familiar partners, survival and reproductive success in year x+1 was similar for males and females that did or did not switch territories. Males had a higher probability of producing chicks after switching than before, but females were more likely to lose their clutch after switching. For both sexes, birds that switched territories were as successful as the birds that replaced them on their former territories. We conclude that high site fidelity in willow ptarmigan is maintained because of the benefits of pairing with a familiar partner.