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Summary: Point sources such as wastewater treatment plants and agricultural facilities may have a role in the dissemination of antibiotic‐resistant bacteria (ARB) and antibiotic resistance genes (ARG). To analyse the evidence for increases in ARB in the natural environment associated with these point sources of ARB and ARG, we conducted a systematic review. We evaluated 5,247 records retrieved through database searches, including both studies that ascertained ARG and ARB outcomes. All studies were subjected to a screening process to assess relevance to the question and methodology to address our review question. A risk of bias assessment was conducted upon the final pool of studies included in the review. This article summarizes the evidence only for those studies with ARB outcomes (n = 47). Thirty‐five studies were at high (n = 11) or at unclear (n = 24) risk of bias in the estimation of source effects due to lack of information and/or failure to control for confounders. Statistical analysis was used in ten studies, of which one assessed the effect of multiple sources using modelling approaches; none reported effect measures. Most studies reported higher ARB prevalence or concentration downstream/near the source. However, this evidence was primarily descriptive and it could not be concluded that there is a clear impact of point sources on increases in ARB in the environment. To quantify increases in ARB in the environment due to specific point sources, there is a need for studies that stress study design, control of biases and analytical tools to provide effect measure estimates. [ABSTRACT FROM AUTHOR]

Florfenicol is an important antibiotic in veterinary medicine that is used extensively in aquaculture, including salmon farming in Chile. We analysed a set of 119 florfenicol-resistant Gram-negative bacilli from seven freshwater Chilean salmon farms for the molecular determinants involved in the florfenicol resistance. Ninety-seven of these strains were glucose non-fermenting bacilli, mainly belonging to the Pseudomonas genus, whereas 22 strains were glucose-fermenters. The floR gene was detected in 26 strains (21.8%) that had been isolated from three of the seven salmon farms. Most of the floR-carrying strains were glucose fermenters (21 strains), and most of the floR-carrying strains were also resistant to streptomycin, chloramphenicol and oxytetracycline. The minimum inhibitory concentrations against florfenicol were assessed in the presence and absence of the efflux pump inhibitor Phe-Arg-β-naphthylamide (MC-207,110). There was evidence that in the majority of non-fermenting bacteria (82 strains), florfenicol resistance was at least partially mediated by non-specific efflux pump systems. Given the diversity of antibiotic resistance patterns observed in this study in the floR-positive isolates, a single antibiotic has the potential to co-select for a diversity of resistances. For this reason, human health as well as animal health can potentially be impacted by the use of antibiotics in aquaculture. To assess this potential risk, future studies should focus on the ability of different antibiotics used in aquatic environments to co-select for multiple resistances, the molecular basis of this diversity of resistance, and whether the genes conferring resistance can be transferred to other bacteria, including those of human health concern. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the level of genetic diversity of Klebsiella pneumoniae isolated from clinical mastitis cases and to define genotypes most commonly associated with the disease. Individual quarter milk samples were collected from a single privately owned dairy herd over a 2-yr period and submitted to the Laboratory for Udder Health, Minnesota Veterinary Diagnostic Laboratory, University of Minnesota, for bacteriological culture. Eighty-four K. pneumoniae isolates were obtained and fingerprinted by repetitive DNA sequence PCR, 43 by pulsed-field gel electrophoresis (PFGE), and 29 by multilocus sequence typing (MLST). Significant genetic diversity was observed among the isolates regardless of the fingerprinting method used. Simpson's diversity index was 93.5, 96.1, and 97.0% when analyzed by repetitive DNA sequence PCR (n = 84), pulse field gel electrophoresis (n = 43), and MLST (n = 29), respectively. In some cases more than 1 genotype was obtained from a single milk sample originating from an individual quarter. The majority of infections were observed during the winter and accounted for 69.0% of K. pneumoniae mastitis cases. There was a negative correlation between a matrix of fingerprints similarity and a matrix of temporal distances. The MLST results revealed 5 new and novel allelic types, which have not been previously reported in the MLST database. Three isolates shared MLST types with human clinical isolates, raising the possibility that some K. pneumoniae isolates, of bovine origin, may be capable of causing disease in humans. There were 21 genotypes present within the herd, and there was no evidence for nonrandom distribution of genotypes uniquely associated with mastitis. We have shown, using 3 distinct genotyping methods, that K. pneumoniae isolated from clinical mastitis within a single dairy herd is caused by a genetically diverse population and that multiple genotypes can be isolated from a mastitic quarter. The data suggest that mastitis can be caused by a variety of K. pneumoniae genotypes. Diverse genotypes may have different levels of invasiveness and virulence and may originate from various sources within the dairy. [ABSTRACT FROM AUTHOR]

We used behavioural observations and mitochondrial DNA (mtDNA) sequence analysis to examine demographic and genetic structure within and among home-range groups of desert bighorn sheep (Ovis canadensis) ewes in the Peninsular Ranges of southern California, USA. We identified substantial genetic variation in the first 515 bp of the mtDNA control region and determined that seven haplotypes were distributed in a nonrandom fashion among these ewe subpopulations. Although a significant (P < 0.01) amount of mtDNA variation (33%) was partitioned among home-range groups, we did not find strong evidence for matrilineal substructuring within these groups. Based on analyses of molecular variance, and comparisons of behavioural associations and distances between centres of activity, we concluded that within a given home-range group, bighorn sheep ewes generally associate with other ewes based on their availability rather than their matrilineal relationships. Our results also supported the conclusion that multiple ewe subpopulations exist within the Peninsular Ranges, and that these subpopulations are the most basic demographic and genetic units. [ABSTRACT FROM AUTHOR]

Despite advances in controlling mastitis (inflammation of the mammary gland), udder infections caused by Klebsiella pneumoniae continue to affect dairy cattle. Mastitis caused by K. pneumoniae responds poorly to antibiotic treatment, and as a consequence, infections tend to be severe and long lasting. We sought to determine whether a nonrandom distribution of specific genotypes of K. pneumoniae was associated with mastitis from 6 dairy herds located in 4 different states. A total of 635 isolates were obtained and fingerprinted by repetitive DNA sequence PCR. Significant genetic diversity was observed in 4 of the 6 dairy herds analyzed, and a total of 49 genotypic variants were identified. Within a herd, Simpson's diversity indices were 91.0, 94.1, 91.7, 88.6, 53.3, and 64.3% for dairies A, B, C, D, E, and F, respectively. The association between matrices of genetic similarity and matrices of temporal distance was negative in all the dairies analyzed. Four dairies had a high incidence of K. pneumoniae mastitis during the winter. The majority of genotypes were unique to herds of origin, and only 5 genotypes were detected in more than 2 dairies. Genotype 1 (arbitrary designation) occurred most frequently across dairies and was found in 25.2% of all mastitis cases and among 22.8% of reinfected and culled cows in dairy A. Specific genotypes also tended to be associated with a specific bedding type and dairy location. Analysis of molecular variance showed that 18% of the genetic diversity was due to variation among herds within states, and 82% of the genetic diversity was accounted for by variation of genotypes within herds. The data support the idea that mastitis is caused by a diverse group of K. pneumoniae genotypes and thus has major implications for the diagnosis, prevention, and treatment of udder infections in dairy cows. [ABSTRACT FROM AUTHOR]

This paper summarizes the gaps and challenges related to animal production, health, and food safety as discussed by a panel at the 1st International Symposium of Food Safety (ISFS) in Santiago, Chile, in December 2016. Participating representatives of academia, industry, and government and statements from the audience confirmed that food safety is essential for increasing food security. First, panelists identified the need for a science-based regulatory framework to implement effective regulations. Second, they highlighted the importance of a risk analysis framework to quantify the risk of the potential for antimicrobial resistance associated with the use of antimicrobials, and the need of studies to evaluate foodborne prevention/control strategies. Third, the challenges of filling the gaps between industry and academia were addressed, including examples of successful collaboration, opportunities, and weakness identified by industry. Finally, challenges in animal food production included issues related to changing consumer preferences, animal welfare, the use of antimicrobials, and sustainable animal production. The symposium provided a regional platform to share experiences from the implementation of methods and approaches for food safety. The roundtable successfully explored the future science and technology challenges that are of strategic importance for Chile and the region in animal health and food safety., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Morphologic assessment of spermatozoa is an integral component in the analysis of semen. Whether a technician rapidly screening semen quality at a commercial stud, a veterinarian performing breeding soundness examinations, a clinician at a reference andrology laboratory providing auditing or diagnostic services, or a researcher evaluating morphology as a part of a fertility study, it is important to make an informed decision regarding the number of spermatozoa to include in the morphology assessment. Application of basic statistical principles such as the nature of proportions, level of confidence in an observed value, and the interaction of sample size with precision, can and should be used in the decision process. This paper outlines in detail the application of these statistical principles in relation to the morphologic assessment of spermatozoa. Guidelines on how these principles can be utilized in practical situations are discussed. Additionally, methodologies for comparison of results within and between laboratories (an area easily prone to misinterpretation) are reviewed. It is hoped that through the use of these fundamental statistical principles, this paper will bring clarity and delineation to the science of quantifying the morphology of spermatozoa.

Central to the development of rational trade policies pertaining to bluetongue virus (BTV) infection is determination of the risk posed by ruminants previously exposed to the virus. Precise determination of the maximal duration of infectious viremia is essential to the development of an appropriate quarantine period prior to movement of animals from BTV-endemic to BTV-free regions. The objective of this study was to predict the duration of detectable viremia in BTV-infected cattle using a probabilistic modeling analysis of existing data. Data on the duration of detectable viremia in cattle were obtained from previously published studies. Data sets were created from a large field study of naturally infected cattle in Australia and from experimental infections of cattle with Australian and US serotypes of BTV. Probability distributions were fitted to the pooled empirical data, and the 3 probability distributions that provided the best fit to the data were the gamma, Weibull, and lognormal probability distributions. These asymmetric probability distributions are often well suited for decay processes, such as the time to termination of detectable viremia. The analyses indicated a > 99% probability of detectable BTV viremia ceasing after < or = 9 weeks of infection in adult cattle and after a slightly longer interval in BTV-infected, colostrum-deprived newborn calves.

A general problem for microbiologists is determining the number of phenotypically similar colonies growing on an agar plate that must be analyzed in order to be confident of identifying all of the different strains present in the sample. If a specified number of colonies is picked from a plate on which the number of unique strains of bacteria is unknown, assigning a probability of correctly identifying all of the strains present on the plate is not a simple task. With Escherichia coli of avian cellulitis origin as a case study, a statistical model was designed that would delineate sample sizes for efficient and consistent identification of all the strains of phenotypically similar bacteria in a clinical sample. This model enables the microbiologist to calculate the probability that all of the strains contained within the sample are correctly identified and to generate probability-based sample sizes for colony identification. The probability of cellulitis lesions containing a single strain of E. coli was 95.4%. If one E. coli strain is observed out of three colonies randomly selected from a future agar plate, the probability is 98.8% that only one strain is on the plate. These results are specific for this cellulitis E. coli scenario. For systems in which the number of bacterial strains per sample is variable, this model provides a quantitative means by which sample sizes can be determined.

During a routine telemetry flight of the Mojave Desert (California, USA) in August 1995, mortality signals were detected from two of 12 radio-collared female desert bighorn sheep (Ovis canadensis) in the vicinity of Old Dad Peak in San Bernardino County (California). A series of field investigations determined that at least 45 bighorn sheep had died near two artificial water catchments (guzzlers), including 13 bighorn sheep which had presumably drowned in a guzzler tank. Samples from water contaminated by decomposing bighorn sheep carcasses and hemolyzed blood from a fresh bighorn sheep carcass were tested for the presence of pesticides, heavy metals, strychnine, blue-green algae, Clostridium botulinum toxin, ethylene glycol, nitrates, nitrites, sodium, and salts. Mouse bioassay and enzyme-linked immunosorbent assay detected type C botulinum toxin in the hemolyzed blood and in fly larvae and pupae. This, coupled with negative results from other analyses, led us to conclude that type C botulinum poisoning was most likely responsible for the mortality of bighorn sheep outside the guzzler tank.

Avian cellulitis in broiler chickens is characterized by subcutaneous lesions that result in economic losses because of the partial or complete condemnation of the carcasses at processing. Escherichia coli is the primary causative agent of this condition. Previous research with a biotyping system found that the E. coli of cellulitis origin were unique to each ranch, suggesting that these E. coli were endemic within the ranch environment. The objective of our study was to analyze the genetic variability of E. coli isolates associated with cellulitis. We analyzed the genetic relatedness of the isolates in relation to the houses, ranches, and complexes in which the broilers were grown. This analysis enabled us to assess the spatial heterogeneity, or genetic diversity on a spatial scale, of the isolates. Forty-nine broilers with cellulitis lesions were necropsied. These broilers came from six houses on four ranches on three complexes that had been placed with chicks from the same hatchery within a 2-wk period. Isolates of E. coli from the lesions were DNA fingerprinted by pulsed-field gel electrophoresis. Relatedness among isolates was determined with the Dice coefficient and an unweighted pair group method with average linkages cluster analysis. The complexes possessed isolates with a variety of DNA fingerprints, yet each complex appeared to have isolates with a unique set of DNA fingerprints. Isolates from the same complex tended to form clusters with similarity coefficients greater than 90%. Isolates from different complexes were genetically distinct. This heterogeneity at the level of the complex suggests that isolates were not disseminated from a source common to the complexes. The spatial heterogeneity of the E. coli isolates in this study implies an endemic population of cellulitis-associated E. coli exists in the broiler house environment.

Objective: To develop a model of bovine respiratory syncytial virus (BRSV) infection that induces severe disease similar to that seen in some cattle with naturally acquired BRSV infection., Animals: 25 male Holstein calves, 8 to 16 weeks old., Procedure: 17 calves were given a low-passage field isolate of BRSV by aerosolization; 8 control calves were given supernatant from noninfected cell culture. Disease was characterized by evaluating clinical signs, virus isolation and pulmonary function tests, and results of blood gas analysis, gross and histologic postmortem examination, and microbiologic testing., Results: Cumulative incidence of cough, harsh lung sounds, adventitious sounds, and dyspnea and increases in rectal temperature and respiratory rate were significantly greater in infected calves. Three infected calves developed extreme respiratory distress and were euthanatized 7 days after inoculation. Virus was isolated from nasal swab specimens from all infected calves but not from mock infected calves. On day 7 after inoculation, mean PaO2 and PaCO2 were significantly lower, and pulmonary resistance was significantly higher, in infected calves. During necropsy, infected calves had varying degrees of necrotizing and proliferative bronchiolitis and alveolitis with syncytial formation. The 3 calves euthanatized on day 7 had emphysematous bullae in the caudal lung lobes; 1 had unilateral pneumothorax., Conclusion and Clinical Relevance: Severe disease similar to that seen in some cattle with naturally acquired BRSV infection can be induced in calves with a single aerosol exposure of a low-passage clinical isolate of BRSV. Our model will be useful for studying the pathogenesis of BRSV infection and for evaluating vaccines and therapeutics.

Formalin-inactivated respiratory syncytial virus (FI-RSV) vaccination has been associated with severe disease in humans. Research in mice suggests that FI-RSV may prime for decreased interferon gamma (IFN-gamma) production at subsequent infection. Interferon-gamma production by peripheral blood mononuclear cells (PBMC) was measured following challenge of calves vaccinated with FI-BRSV to determine whether a similar mechanism is operative in a host naturally susceptible to RSV. Eight-week old male Holstein calves were administered FI-BRSV and mock challenge (V/M, n = 6); mock vaccination and BRSV challenge (M/C, n = 6) or FI-BRSV and BRSV challenge (V/C, n = 7). Vaccine was administered twice at a 2-week interval; challenge followed one month later. On days 0, 5 and 10 postchallenge (PC), PBMC were stimulated in vitro for 24 h with live BRSV, concanavalin A (positive control) or spent media (negative control). Supernatants were assayed for IFN-gamma using ELISA. Interferon-gamma production by BRSV-stimulated PBMC was increased in M/C and V/C calves as compared to V/M calves on day 5 PC (p < 0.015); and increased in M/C calves compared to V/C and V/M calves on day 10 PC (p < 0.015). Over time postchallenge, a significant increase in IFN-gamma production by BRSV-stimulated PBMC was seen in M/C calves (p < 0.025) but not in V/C calves. FI-BRSV vaccination of calves led to diminished IFN-gamma production postchallenge. Decreased IFN-gamma production may have contributed to impaired viral clearance and enhanced disease in FI-BRSV vaccinated calves.

A critical issue has been the observation that vaccination of children with a formalin-inactivated respiratory syncytial virus (RSV) vaccine is associated with disease enhancement. We have taken advantage of bovine RSV and our experience with this disease in calves to develop a natural model that parallels human disease. Using formalin-inactivated bovine RSV vaccine calves were either sham-vaccinated/infected, vaccinated/infected, or vaccinated/sham-infected and their clinical signs, pulmonary function, and histological lung lesions quantitatively scored. Interestingly there was significantly greater disease in vaccinated/infected calves and histological lesions in calves were similar to those of affected children. Finally, we note that vaccination did not induce neutralizing antibodies, but IgG antibodies were detected by ELISA. Our model of RSV enhanced disease is important because it provides quantifiable evidence of disease severity that can be applied to evaluate the mechanisms of immunopathology and the safety of candidate RSV vaccines.

Objective: To determine whether ampicillin- and tetracycline-resistant strains of Pasteurella multocida and P haemolytica isolated from California cattle with pneumonia were spatially and temporally clustered and to compare overall estimates of percentages of these isolates resistant to these antimicrobials with estimates obtained on the basis of regional and temporal information., Design: Epidemiologic study., Sample Population: Records of P multocida and P haemolytica isolates obtained from lung or tracheal wash samples collected from California cattle with pneumonia between July 1, 1991 and July 31, 1996. Only isolates obtained from samples submitted by dairies and calf ranches were used., Procedure: Spatial clustering of ampicillin- and tetracycline-resistant isolates was assessed by use of nearest-neighbor and Cuzick and Edwards' analyses. Linear clustering along a north-south line was assessed by use of runs and maximum length of runs tests. Temporal clustering was assessed by use of scan tests. Spatial-temporal clustering was assessed by use of Barton's method. Regional estimates of percentages of P multocida and P haemolytica resistant to ampicillin or tetracycline were calculated., Results: There was significant spatial clustering of resistant isolates and significant linear clustering along a north-south line. Significant differences in regional estimates of percentages of antimicrobial-resistant isolates were found., Clinical Implications: Results support the hypothesis that antimicrobial-resistant organisms can be clustered at the local level and reinforce the need to establish regional estimates of percentages of bacterial isolates that will be susceptible to commonly used antimicrobials.

We sampled sympatric bighorn sheep (Ovis canadensis, n = 31), mule deer (Odocoileus hemionus, n = 38), and domestic cattle (n = 26) in the San Bernadino Mountains of southern California (USA) for the presence of Psoroptes spp. mites and for serologic evidence of exposure to bluetongue virus (BTV) and Babesia spp. From 1991 through 1994, Psoroptes spp. infestations were found on 12 (44%) of 27 bighorn sheep. No mites were found on mule deer or cattle. The BTV serum antibody prevalence in a cohort of 26 cattle ranged from 17 to 89%. There was no evidence of exposure to BTV in the bighorn sheep or mule deer. The cumulative serum antibody prevalence of Babesia spp. during the study was 35% in 26 bighorn sheep and 85% in 20 mule deer, while antibodies were not detected in a cohort of cattle when they were sampled in May (n = 23) and December (n = 22) of 1992. Based on these results, we concluded that infestation with Psoroptes spp. and exposure to BTV was limited to bighorn sheep and cattle, respectively. In contrast, Babesia spp. infections appeared to be common in both mule deer and bighorn sheep while there was no evidence of exposure in cattle.

66 individuals were given a questionnaire during the initial visit to a veterinary clinic for homeless pet owners. Among the 35 men and 31 women, 32 had been homeless for 6 mo. or less and were termed the acutely homeless subgroup, and 34 had been homeless multiple times or for more than 6 mo. and were termed the chronically homeless subgroup. In responding to the Lexington Attachment to Pets Scale, both men and women participants had significantly higher mean scores on attachment to their pets than did the scale's standardization population. Participants did not differ from the normative sample of adults on the Beck Hopelessness Scale. Both men and women participants stated a preference for being rehoused. 93% of men and 96% of women said that housing would not be acceptable if pets were not allowed. 61% of the men and 33% of the women stated they would be willing to live anywhere pets were allowed except in a shelter. Reluctance to live in a shelter was significantly greater among chronically homeless men than other subgroups, and they also had low desire to be rehoused. A majority of the participants had been refused housing because they had pets. Attempts to rehouse homeless individuals who have pets are likely to be unsuccessful unless accommodation for pets is included.

Background: Topical tretinoin (retinoic acid) modifies fine wrinkles and certain other features of human skin damaged by exposure to the sun (photodamage), but histologic changes do not account for this improvement. In mice with photodamage induced by ultraviolet light, effacement of fine wrinkles by tretinoin is correlated with dermal collagen synthesis but not with histologic changes. We investigated whether collagen synthesis was reduced in photodamaged human skin and, if so, whether it could be restored by treatment with topical tretinoin., Methods: Biopsies of photodamaged skin from the extensor aspect of the forearm and skin from the buttocks, which had been protected from the sun, were performed on 26 healthy subjects. In addition, 29 patients with photodamaged skin were treated for 10 to 12 months with a daily application of 0.1 percent tretinoin cream (15 patients) or vehicle cream (14 patients). Skin-biopsy specimens obtained at base line and after treatment were assessed immunohistologically for evidence of dermal collagen I formation (collagen synthesis)., Results: Collagen I formation was 56 percent less in the papillary dermis of photodamaged skin than in skin protected from the sun (P < 0.001) and was correlated with the clinical severity of photodamage (r = -0.58, P = 0.002). Treatment of photodamaged skin with tretinoin produced an 80 percent increase in collagen I formation, as compared with a 14 percent decrease in collagen formation with the use of vehicle alone (P = 0.006)., Conclusions: The formation of collagen I is significantly decreased in photodamaged human skin, and this process is partly restored by treatment with tretinoin.

The maintenance of sterility of the light handle in an economical and effective manner can be difficult. Heavy-duty aluminum foil is suggested as a simple and inexpensive material to be used to maintain such sterility in the clinical practice of oral and maxillofacial surgery.

The proper alignment of the proximal and distal segments after the sagittal split ramus osteotomy (SSRO) has been a major concern since this procedure was first performed. Because of this problem, a comparison was made between a superior border wiring technique and an inferior border wiring technique. This involved the preoperative and postoperative lateral cephalograms of 35 patients from the Department of Oral Surgery at the Medical College of Georgia who received a SSRO with advancement. Nineteen patients received an inferior border wire and 16 patients received a superior border wire. The areas studied were anterosuperior rotation of the proximal segment, increase in gonial angle, and condylar sag. A cephalometric evaluation and a computer analysis were performed. It was found that the inferior border wiring technique produces a statistically significant lesser amount of anterosuperior rotation of the proximal segment and less increase in gonial angle than the superior border wiring technique. Because of these findings, it was felt that the inferior border wiring techniques produce less displacement of the proximal segment in the SSRO advancement.