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Dive into the research topics where Charles L. Hofacre is active.

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Featured researches published by Charles L. Hofacre.


Applied and Environmental Microbiology | 2003

Diversity and Succession of the Intestinal Bacterial Community of the Maturing Broiler Chicken

Jiangrang Lu; Umelaalim Idris; Barry G. Harmon; Charles L. Hofacre; John J. Maurer; Margie D. Lee

ABSTRACT The diversity of bacterial floras in the ilea and ceca of chickens that were fed a vegetarian corn-soy broiler diet devoid of feed additives was examined by analysis of 1,230 partial 16S rRNA gene sequences. Nearly 70% of sequences from the ileum were related to those of Lactobacillus, with the majority of the rest being related to Clostridiaceae (11%), Streptococcus (6.5%), and Enterococcus (6.5%). In contrast, Clostridiaceae-related sequences (65%) were the most abundant group detected in the cecum, with the other most abundant sequences being related to Fusobacterium (14%), Lactobacillus (8%), and Bacteroides (5%). Statistical analysis comparing the compositions of the different 16S rRNA libraries revealed that population succession occurred during some sampling periods. The significant differences among cecal libraries at 3 and 7 days of age, at 14 to 28 days of age, and at 49 days of age indicated that successions occurred from a transient community to one of increasing complexity as the birds aged. Similarly, the ileum had a stable bacterial community structure for birds at 7 to 21 days of age and between 21 to 28 days of age, but there was a very unique community structure at 3 and 49 days of age. It was also revealed that the composition of the ileal and cecal libraries did not significantly differ when the birds were 3 days old, and in fact during the first 14 days of age, the cecal microflora was a subset of the ileal microflora. After this time, the ileum and cecum had significantly different library compositions, suggesting that each region developed its own unique bacterial community as the bird matured.


Applied and Environmental Microbiology | 2003

Evaluation of Broiler Litter with Reference to the Microbial Composition as Assessed by Using 16S rRNA and Functional Gene Markers

Jingrang Lu; Susan Sanchez; Charles L. Hofacre; John J. Maurer; Barry G. Harmon; Margie D. Lee

ABSTRACT Very little is known about the microbial composition of animal bedding wastes, including poultry litter, and what is known has been deduced from standard culture methods, by which some fastidious organisms that exist in the environment may not be detected. We evaluated the bacterial composition of poultry litter by using a combination of culture and molecular detection. Total aerobic bacteria in poultry litter were detected by culture at 109 CFU/g of material. Enteric bacteria such as Enterococcus spp. and coliforms composed 0.1 and 0.01%, respectively, of the total aerobic cultivatable bacteria in poultry litter; no Salmonella strains were detected by culture. In order to characterize the most abundant bacterial groups, we sequenced 16S ribosomal DNA (rDNA) genes amplified by PCR with microbial community DNA isolated from poultry litter as the template. From the 16S rDNA library, 31 genera were identified. Twelve families or groups were identified with lactobacilli and Salinococcus spp. forming the most abundant groups. In fact, 82% of the total sequences were identified as gram-positive bacteria with 62% of total belonging to low G+C gram-positive groups. In addition to detection of 16S rDNA sequences associated with the expected fecal bacteria present in manure, we detected many bacterial sequences for organisms, such as Globicatella sulfidofaciens, Corynebacterium ammoniagenes, Corynebacterium urealyticum, Clostridium aminovalericum, Arthrobacter sp., and Denitrobacter permanens, that may be involved in the degradation of wood and cycling of nitrogen and sulfur. Several sequences were identified in the library for bacteria associated with disease in humans and poultry such as clostridia, staphylococci, and Bordetella spp. However, specific PCR targeting other human and veterinary pathogens did not detect the presence of Salmonella, pathogenic Escherichia coli, Campylobacter spp., Yersinia spp., Listeria spp., or toxigenic staphylococci. PCR and DNA hybridization revealed the presence of class 1 integrons with gene cassettes that specify resistance to aminoglycosides and chloramphenicol. Only from understanding the microbial community of animal wastes such as poultry litter can we manage animal disease and limit the impact of animal waste on the environment and human and animal health.


Applied and Environmental Microbiology | 2007

Impact of Antimicrobial Usage on Antimicrobial Resistance in Commensal Escherichia coli Strains Colonizing Broiler Chickens

J. L. Smith; D. J. V. Drum; Y. Dai; J. M. Kim; Susan Sanchez; John J. Maurer; Charles L. Hofacre; Margie D. Lee

ABSTRACT Escherichia coli strains isolated from commercial broilers and an experimental flock of chickens were screened to determine phenotypic expression of antimicrobial resistance and carriage of drug resistance determinants. The goal of this study was to investigate the influence of oxytetracycline, sarafloxacin, and enrofloxacin administration on the distribution of resistance determinants and strain types among intestinal commensal E. coli strains isolated from broiler chickens. We detected a high prevalence of resistance to drugs such as tetracycline (36 to 97%), sulfonamides (50 to 100%), and streptomycin (53 to 100%) in E. coli isolates from treated and untreated flocks. These isolates also had a high prevalence of class 1 integron carriage, and most of them possessed the streptomycin resistance cassette, aadA1. In order to investigate the contribution of E. coli strain distribution to the prevalence of antimicrobial resistance and the resistance determinants, isolates from each flock were DNA fingerprinted by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR. Although very diverse E. coli strain types were detected, four ERIC strain types were present on all of the commercial broiler farms, and two of the strains were also found in the experimental flocks. Each E. coli strain consisted of both susceptible and antimicrobial agent-resistant isolates. In some instances, isolates of the same E. coli strain expressed the same drug resistance patterns although they harbored different tet determinants or streptomycin resistance genes. Therefore, drug resistance patterns could not be explained solely by strain prevalence, indicating that mobile elements contributed significantly to the prevalence of resistance.


Avian Diseases | 2006

Potential Impacts of Antibiotic Use in Poultry Production

Randall S. Singer; Charles L. Hofacre

Abstract The ways in which antibiotics are used in poultry production have changed considerably during the past decade, mainly because of concerns about potential negative human health consequences caused by these uses. Human health improvements directly attributable to these antibiotic-use changes are difficult to demonstrate. Given that some antibiotics will continue to be used in the poultry industry, methods are needed for estimating the causal relationship between these antibiotic uses and actual animal and human health impacts. This is a challenging task because of the numerous factors that are able to select for the emergence, dissemination, and persistence of antibiotic resistance. Managing the potential impacts of antibiotic use in poultry requires more than a simple estimation of the risks that can be attributed to the use of antibiotics in poultry. Risk models and empirical studies that evaluate interventions that are capable of minimizing the negative consequences associated with specific antibiotic uses are desperately needed.


Applied and Environmental Microbiology | 2003

Rapid Detection of Campylobacter coli, C. jejuni, and Salmonella enterica on Poultry Carcasses by Using PCR-Enzyme-Linked Immunosorbent Assay

Yang Hong; Mark E. Berrang; Tongrui Liu; Charles L. Hofacre; Susan Sanchez; Lihua Wang; John J. Maurer

ABSTRACT Contamination of retail poultry by Campylobacter spp. and Salmonella enterica is a significant source of human diarrheal disease. Isolation and identification of these microorganisms require a series of biochemical and serological tests. In this study, Campylobacter ceuE and Salmonella invA genes were used to design probes in PCR-enzyme-linked immunosorbent assay (ELISA), as an alternative to conventional bacteriological methodology, for the rapid detection of Campylobacter jejuni, Campylobacter coli, and S. enterica from poultry samples. With PCR-ELISA (40 cycles), the detection limits for Salmonella and Campylobacter were 2 × 102 and 4 × 101 CFU/ml, respectively. ELISA increased the sensitivity of the conventional PCR method by 100- to 1,000-fold. DNA was extracted from carcass rinses and tetrathionate enrichments and used in PCR-ELISA for the detection of Campylobacter and S. enterica, respectively. With PCR-ELISA, Salmonella was detected in 20 of 120 (17%) chicken carcass rinses examined, without the inclusion of an enrichment step. Significant correlation was observed between PCR-ELISA and cultural methods (kappa = 0.83; chi-square test, P < 0.001) with only one false negative (1.67%) and four false positives (6.67%) when PCR-ELISA was used to screen 60 tetrathionate enrichment cultures for Salmonella. With PCR-ELISA, we observed a positive correlation between the ELISA absorbance (optical density at 405 nm) and the campylobacter cell number in carcass rinse, as determined by standard culture methods. Overall, PCR-ELISA is a rapid and cost-effective approach for the detection and enumeration of Salmonella and Campylobacter bacteria on poultry.


Avian Diseases | 1986

Necrotic Enteritis in Cage-Reared Commercial Layer Pullets

Broussard Ct; Charles L. Hofacre; Page Rk; Fletcher Oj

Necropsy of five 12-week-old pullets from a flock of 99,300 suffering from an increased mortality rate revealed enlarged, gas-filled intestines, the mucosal surfaces of which had the dirty turkish towel appearance typical of necrotic enteritis. Although the pullets had been raised entirely in cages, intestinal scrapings revealed the presence of Eimeria maxima. Histopathological findings were compatible with necrotic enteritis. Clostridium perfringens was isolated by anaerobic culture from the intestines. Mortality returned to normal after bacitracin and amprolium were added to the feed.


Avian Diseases | 2010

Bacteriophage Therapy for Control of Necrotic Enteritis of Broiler Chickens Experimentally Infected With Clostridium perfringens

Ross W. Miller; James T. Skinner; Alexander Sulakvelidze; G. Mathis; Charles L. Hofacre

Abstract Several lytic bacteriophages effective at destroying a genetically diverse population of Clostridium perfringens were isolated from the environment, extensively characterized, and used to formulate a multivalent bacteriophage cocktail designated “INT-401.” Two in vivo studies were conducted to determine the cocktails efficacy in controlling necrotic enteritis (NE) caused by C. perfringens. The first study investigated the efficacy of INT-401 and a bacteriophage-derived, toxoid-type vaccine in controlling NE in C. perfringens–challenged broiler chickens. The study was designed as a proof-of-concept battery cage study with birds reared until 28 days old. Compared with the mortality observed with the C. perfringens–challenged but untreated chickens, oral administration of INT-401 significantly (P < 0.05) reduced the mortality of the C. perfringens–challenged birds by 92%. Overall, INT-401 was more effective than the toxoid vaccine in controlling active C. perfringens infection. The second study was conducted to investigate the effectiveness of the cocktail when administered via oral gavage, feed, or drinking water. The study was conducted in floor pens, with birds reared to 42 days old. INT-401 administered by all three methods significantly (P < 0.05) reduced mortality. Weight gain and feed conversion ratios were significantly better in the C. perfringens–challenged chickens treated with INT-401 than in the C. perfringens–challenged, phage-untreated control birds. The data indicate that delivering INT-401 to broiler chickens via their drinking water or feed may be an effective means for controlling NE caused by C. perfringens and may improve weight gain and feed conversion ratios in birds with clinical or subclinical NE.


Avian Diseases | 1998

Use of Aviguard and Other Intestinal Bioproducts in Experimental Clostridium perfringens-associated Necrotizing Enteritis in Broiler Chickens

Charles L. Hofacre; Froyman R; Gautrias B; George B; Mark A. Goodwin; John Brown

Clostridium perfringens-associated necrotic enteritis (CPANE) is a common problem among rapidly growing broiler strains of chickens that are raised intensively in modern microenvironments. The purpose of this study was to compare the use of Aviguard and three other intestinal bioproducts (two normal gut flora [NGF] products and one probiotic product) in experimental CPANE in broiler chickens. Male broiler chicks were housed in the same environmentally controlled facility and given one of six treatments. The necrotic enteritis infection model (NEIM) used in the present study was effective in inducing CPANE intestinal gross lesions in broiler chickens. Equally important, Aviguard was found to be significantly more effective than either the other two NGF products or the probiotic for reducing gross lesions induced by the NEIM. In addition, Aviguard/NEIM-treated chicks ate more feed and had better feed efficiency than their NGF- or probiotic/NEIM-treated counterparts. Other significant differences among these four reconstituted microbial preparations were not found. Results from this study have additional importance because they further support the use of reconstituted microbial preparations as novel and effective alternatives to antibiotics that can reduce the severity of C. perfringens-associated necrotic enteritis challenge in broilers.


Avian Diseases | 2005

Molecular Detection and Serotyping of Infectious Bronchitis Virus from FTA® Filter Paper

Hugo Moscoso; Erine O. Raybon; Stephan G. Thayer; Charles L. Hofacre

Abstract We investigated the feasibility of using Flinders Technology Associates (FTA®) filter cards for the storage of allantoic fluid containing an infectious bronchitis virus (IBV), such as Arkansas-DPI, Connecticut, and Massachusetts, and for their identification by reverse transcriptase (RT)-polymerase chain reaction (PCR) and characterization by restriction fragment length polymorphism (RFLP) or nucleotide sequencing. FTA® paper is a cotton-based cellulose membrane containing lyophilized chemicals that lyses many types of bacteria and viruses. IBV was inactivated upon contact with the FTA®, as shown by the inability of the virus to be propagated in embryonating chicken eggs. RT-PCR of the S1 gene showed that viral RNA in allantoic fluid remained stable after storage on FTA® filter cards and that the stability was time and temperature sensitive for the large (1700 base pair [bp]) but not the small (383 bp) PCR products. Analysis of the amplified products showed that molecular characterization is feasible in allantoic fluid stored on FTA® under nonfavorable environmental conditions (41 C) for at least 15 days. The use of FTA® cards for the collection, transport, and storage of IBV–containing samples is safe, inexpensive, and adequate for molecular diagnosis. We propose that specimens coming from overseas on FTA® cards would be first analyzed by RT-PCR with primers yielding a 1700-bp product followed by RFLP of the positive cases. Negative cases would be analyzed with primers yielding a 383-bp product (to exclude detrimental effect of the storage conditions) followed by nucleotide sequencing of the positive cases.


Applied and Environmental Microbiology | 2013

Enumeration of Salmonella and Campylobacter spp. in Environmental Farm Samples and Processing Plant Carcass Rinses from Commercial Broiler Chicken Flocks

Roy D. Berghaus; Stephan G. Thayer; Bibiana F. Law; Rita M. Mild; Charles L. Hofacre; Randall S. Singer

ABSTRACT A prospective cohort study was performed to evaluate the prevalences and loads of Salmonella and Campylobacter spp. in farm and processing plant samples collected from 55 commercial broiler chicken flocks. Environmental samples were collected from broiler houses within 48 h before slaughter, and carcass rinses were performed on birds from the same flocks at 4 different stages of processing. Salmonella was detected in farm samples of 50 (90.9%) flocks and in processing samples of 52 (94.5%) flocks. Campylobacter was detected in farm samples of 35 (63.6%) flocks and in processing samples of 48 (87.3%) flocks. There was a significant positive relationship between environmental farm samples and processing plant carcass rinses with respect to both Salmonella and Campylobacter prevalences and loads. Campylobacter loads were significantly higher than Salmonella loads, and the correlations between samples collected from the same flocks were higher for Campylobacter than they were for Salmonella. Boot socks were the most sensitive sample type for detection of Salmonella on the farm, whereas litter samples had the strongest association with Salmonella loads in pre- and postchill carcass rinses. Boot socks, drag swabs, and fecal samples all had similar sensitivities for detecting Campylobacter on the farm, and all were more strongly associated with Campylobacter loads in carcass rinses than were litter samples. Farm samples explained a greater proportion of the variability in carcass rinse prevalences and loads for Campylobacter than they did for Salmonella. Salmonella and Campylobacter prevalences and loads both decreased significantly as birds progressed through the processing plant.

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David G. White

Food and Drug Administration

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Sherry Ayers

Food and Drug Administration

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