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Thitaram S.N.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Frank J.F.,University of Georgia | Siragusa G.R.,Poultry Microbiological Safety and Processing Research Unit | Siragusa G.R.,Eurofins | And 9 more authors.
International Journal of Food Microbiology | Year: 2016

Clostridium difficile is commonly associated with a spectrum of disease in humans referred to as C. difficile-associated disease (CDAD) and use of antimicrobials is considered a risk factor for development of disease in humans. C. difficile can also inhabit healthy food animals and transmission to humans is possible. As a result of the complexity and cost of testing, C. difficile is rarely tested for antimicrobial susceptibility. A total of 376 C. difficile strains (94 each from swine and dairy feces, and 188 from beef cattle feces) were isolated from healthy food animals on farms during studies conducted by the National Animal Health Monitoring System. Using the Etest (AB Biodisk, Solna, Sweden), samples were tested for susceptibility to nine antimicrobials implicated as risk factors for CDAD (linezolid, amoxicillin-clavulanic acid, ampicillin, clindamycin, erythromycin, levofloxacin, metronidazole, rifampicin, and vancomycin). Vancomycin was active against all isolates of C. difficile (MIC90 = 3.0 μg/ml) while almost all isolates (n = 369; 98.1%) were resistant to levofloxacin. With the exception of vancomycin, resistance varied by animal species as follows: linezolid (8.5% resistance among swine versus 2.1 and 1.1% resistance among dairy and beef, respectively), clindamycin (56.4% resistance among swine versus 80% and 90.9% resistance among dairy and beef, respectively), and rifampicin (2.1% and 0% resistance among swine and dairy cattle isolates, respectively versus 14.3% resistance among beef isolates). Regardless of species, multiple drug resistance was observed most often to combinations of clindamycin and levofloxacin (n = 195; 51.9%) and ampicillin, clindamycin and levofloxacin (n = 41; 10.9%). The reason for the variability of resistance between animal species is unknown and requires further research. © 2016.


Jackson C.R.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Fedorka-Cray P.J.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Davis J.A.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Barrett J.B.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | And 3 more authors.
Journal of Applied Microbiology | Year: 2010

Aims: In this study, mechanisms of antimicrobial resistance and genetic relatedness among resistant enterococci from dogs and cats in the United States were determined. Methods and Results: Enterococci resistant to chloramphenicol, ciprofloxacin, erythromycin, gentamicin, kanamycin, streptomycin, lincomycin, quinupristin/dalfopristin and tetracycline were screened for the presence of 15 antimicrobial resistance genes. Five tetracycline resistance genes [tet(M), tet(O), tet(L), tet(S) and tet(U)] were detected with tet(M) accounting for approx. 60% (130/216) of tetracycline resistance; erm(B) was also widely distributed among 96% (43/45) of the erythromycin-resistant enterococci. Five aminoglycoside resistance genes were also detected among the kanamycin-resistant isolates with the majority of isolates (25/36; 69%) containing aph(3′)-IIIa. The bifunctional aminoglycoside resistance gene, aac(6′)-Ie-aph(2″)-Ia, was detected in gentamicin-resistant isolates and ant(6)-Ia in streptomycin-resistant isolates. The most common gene combination among enterococci from dogs (n = 11) was erm(B), aac(6′)-Ie-aph(2″)-Ia, aph(3′)-IIIa, tet(M), while tet(O), tet(L) were most common among cats (n = 18). Using pulsed-field gel electrophoresis (PFGE), isolates clustered according to enterococcal species, source and antimicrobial gene content and indistinguishable patterns were observed for some isolates from dogs and cats. Conclusion: Enterococci from dogs and cats may be a source of antimicrobial resistance genes. Significance and Impact of the Study: Dogs and cats may act as reservoirs of antimicrobial resistance genes that can be transferred from pets to people. Although host-specific ecovars of enterococcal species have been described, identical PFGE patterns suggest that enterococcal strains may be exchanged between these two animal species. © 2009 The Society for Applied Microbiology. No claim to US Government works.


PubMed | Quality and Safety Assessment Research Unit, Poultry Microbiological Safety and Processing Research Unit, Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. Department of Agriculture and University of Georgia
Type: Journal Article | Journal: Poultry science | Year: 2016

To estimate the potential for residual antimicrobial solution carryover, surface water accumulation and loss was measured on post-chill carcasses that were either dipped or sprayed with water. For all experiments, broilers were slaughtered, soft or hard scalded, defeathered, and eviscerated. Carcasses were immersion chilled, allowed to drip, and post-chill carcass weight (CW) recorded. For water dip treatment, carcasses were dipped for 0.5min in water and hung by a wing (n = 33) or a leg (n = 30) and CW recorded at 0, 0.5, 1, 2, and 5min post-dip. For water spray treatment, individual carcasses were hung by either the wings (n = 35) or legs (n = 34) from a shackle suspended from a scale. Water was sprayed at 80psi and post-spray CW recorded. Initial water accumulation (0min) for dipped carcasses was not significantly different (P > 0.05) for carcasses hung by the leg (101.0g) or wing (108.8g). Following the 5min drip time, 31g of water remained on the carcasses hung by the leg and only 10g on carcasses hung by the wing (P < 0.05). When carcasses were sprayed with water, initial water accumulation (0min) was 62g for carcasses hung by the legs and 60g for carcasses hung by the wings (P > 0.05). Following the 5min drip time, 1g or no water remained on the sprayed carcasses (P > 0.05). Carcasses that were dipped and hung by a leg for 5min retained significantly more water (31g) than carcasses that were dipped and hung by a wing (10g) or sprayed carcasses hung either way (0.3g) (P < 0.05). Post-chill water dip resulted in significantly higher initial carcass water accumulation than spraying (105g vs. 61g, P < 0.05). Carcass orientation during dripping only affected the amount of retained water for dipped carcasses. Dipped carcasses hung by a leg have the highest potential for residual carcass antimicrobial solution carryover and sprayed carcasses hung by either orientation have the lowest potential for residual antimicrobial solution carryover.


Milner D.S.,University of Nottingham | Till R.,University of Nottingham | Cadby I.,University of Birmingham | Lovering A.L.,University of Birmingham | And 5 more authors.
PLoS Genetics | Year: 2014

Bdellovibrio bacteriovorus invade Gram-negative bacteria in a predatory process requiring Type IV pili (T4P) at a single invasive pole, and also glide on surfaces to locate prey. Ras-like G-protein MglA, working with MglB and RomR in the deltaproteobacterium Myxococcus xanthus, regulates adventurous gliding and T4P-mediated social motility at both M. xanthus cell poles. Our bioinformatic analyses suggested that the GTPase activating protein (GAP)-encoding gene mglB was lost in Bdellovibrio, but critical residues for MglABd GTP-binding are conserved. Deletion of mglABd abolished prey-invasion, but not gliding, and reduced T4P formation. MglABd interacted with a previously uncharacterised tetratricopeptide repeat (TPR) domain protein Bd2492, which we show localises at the single invasive pole and is required for predation. Bd2492 and RomR also interacted with cyclic-di-GMP-binding receptor CdgA, required for rapid prey-invasion. Bd2492, RomRBd and CdgA localize to the invasive pole and may facilitate MglA-docking. Bd2492 was encoded from an operon encoding a TamAB-like secretion system. The TamA protein and RomR were found, by gene deletion tests, to be essential for viability in both predatory and non-predatory modes. Control proteins, which regulate bipolar T4P-mediated social motility in swarming groups of deltaproteobacteria, have adapted in evolution to regulate the anti-social process of unipolar prey-invasion in the "lone-hunter" Bdellovibrio. Thus GTP-binding proteins and cyclic-di-GMP inputs combine at a regulatory hub, turning on prey-invasion and allowing invasion and killing of bacterial pathogens and consequent predatory growth of Bdellovibrio. © 2014.


Ladely S.R.,U.S. Department of Agriculture | Meinersmann R.J.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Plumblee J.R.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Fedorka-Cray P.J.,North Carolina State University1060 William Moore DriveRaleigh 27607North Carolina
Journal of Food Safety | Year: 2016

To determine if Campylobacter isolation method influenced antimicrobial susceptibility results, the minimum inhibitory concentrations (MIC) of nine antimicrobials were compared for 291 pairs of Campylobacter isolates recovered from chicken carcass rinse samples using direct plating and an enrichment method. Among the isolates 64.1% were C. jejuni, 35.7% were C. coli, and 0.2% were C. lari. Direct plating yielded significantly less (P<0.05) C. coli (21.3%) compared to sample enrichment (50.2%). Antimicrobial resistance was most common for tetracycline (41.4%), nalidixic acid (26.3%), and ciprofloxacin (25.9%). Significantly more (P<0.05) C. coli were resistant to nalidixic acid, ciprofloxacin, gentamicin, azithromycin, and erythromycin as compared to C. jejuni isolates. Nonparametric bootstrap analysis of antimicrobial MICs showed no significant differences between direct plating and the enrichment method for any of the antimicrobials tested. These data indicate that bacterial isolation method can bias Campylobacter species recovery. However, isolation method did not significantly affect antimicrobial susceptibility results of C. jejuni or C. coli recovered from broiler carcasses. Practical Applications: To monitor trends in food safety and public health, antimicrobial susceptibility testing of Campylobacter derived from poultry products and infected patients has become common practice in both regulatory food safety and public health programs. Various methods have been employed for Campylobacter recovery including direct plating for enumeration of contamination levels and enrichment protocols for detection of low numbers or injured cells. This study was conducted to determine if the method of Campylobacter isolation from chicken carcass rinsate, direct plating or enrichment, influences antimicrobial susceptibility testing results. © 2016 Wiley Periodicals, Inc.


Kautz M.J.M.,University of Delaware | Dvorzhinskiy A.,University of Delaware | Frye J.G.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Stevenson N.,University of Delaware | Herson D.S.,University of Delaware
Applied and Environmental Microbiology | Year: 2013

Salmonella infection causes a self-limiting gastroenteritis in humans but can also result in a life-threatening invasive disease, especially in old, young, and/or immunocompromised patients. The prevalence of antimicrobial and multidrug-resistant Salmonella has increased worldwide since the 1980s. However, the impact of antimicrobial resistance on the pathogenicity of Salmonella strains is not well described. In our study, a microarray was used to screen for differences in gene expression between a parental strain and a strain of Salmonella enterica serovar Enteritidis with reduced susceptibility (SRS) to the widely used antimicrobial sanitizer dodecyltrimethylammonium chloride (DTAC). Three of the genes, associated with adhesion, invasion, and intracellular growth (fimA, csgG, and spvR), that showed differences in gene expression of 2-fold or greater were chosen for further study. Real-time reverse transcriptase PCR (real-time RT-PCR) was used to confirm the microarray data and to compare the expression levels of these genes in the parental strain and four independently derived SRS strains. All SRS strains showed lower levels of gene expression of fimA and csgG than those of the parental strain. Three of the four SRS strains showed lower levels of spvR gene expression while one SRS strain showed higher levels of spvR gene expression than those of the parental strain. Transmission electron microscopy determined that fimbriae were absent in the four SRS strains but copiously present in the parental strain. All four SRS strains demonstrated a significantly reduced ability to invade tissue culture cells compared to the parental strains, suggesting reduced pathogenicity of the SRS strains. © 2013, American Society for Microbiology.


Adenipekun E.O.,Olabisi Onabanjo University | Jackson C.R.,Bacterial Epidemiology and Antimicrobial Resistance Research Unit | Oluwadun A.,Olabisi Onabanjo University | Iwalokun B.A.,Olabisi Onabanjo University | And 5 more authors.
Microbial Drug Resistance | Year: 2015

Foodborne bacteria are often associated with human infections; these infections can become more complicated to treat if the bacteria are also resistant to antimicrobials. In this study, prevalence, antimicrobial resistance, and genetic relatedness of Escherichia coli among food producing animals from Lagos, Nigeria, was investigated. From December 2012 to June 2013, E. coli were isolated from fecal samples of healthy cattle, chicken, and swine. Antimicrobial susceptibility testing against 22 antimicrobials was performed using broth microdilution with the Sensititre™ system. Clonal types were determined by pulsed-field gel electrophoresis (PFGE). From the analysis, 211/238 (88.7%), 170/210 (81%), and 136/152 (89.5%) samples from cattle, chicken, and swine, respectively, were positive for E. coli. A subset of those isolates (n=211) selected based on β-lactamase production was chosen for further study. Overall, E. coli exhibited the highest resistance to tetracycline (124/211; 58.8%), trimethoprim/sulfamethoxazole (84/211; 39.8%), and ampicillin (72/211; 34.1%). Approximately 40% of the isolates were pan-susceptible, and none of the isolates were resistant to amikacin, cefepime, ceftazidime, ertapenem, meropenem, or tigecycline. Among the resistant isolates, 28 different resistance patterns were observed; 26 of those were characterized as multi-drug resistant (MDR; resistance to ≥2 antimicrobials). One isolate was resistant to 13 different antimicrobials representing five different antimicrobial classes. Using PFGE, MDR E. coli were genetically diverse and overall did not group based on source; identical PFGE patterns were detected among isolates from different sources. These results suggest that isolates cannot be attributed to specific sources, and some may be present across all of the sources. Results from this study indicate that food-producing animals in Nigeria are a reservoir of MDR E. coli that may be transferred to humans via the food chain. © Copyright 2015, Mary Ann Liebert, Inc.

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