Biomedical subjects

Curt Doetkott

Publications and source records attributed to Curt Doetkott.

6 recordsLinked to original sources

PubMed2006

Prevalence and molecular profiles of Salmonella collected at a commercial turkey processing plant.

In this study, whole carcasses were sampled at eight stages on a turkey-processing line and Salmonella prevalence was determined using enrichment techniques. Recovered Salmonella was further characterized using serotyping and the molecular profiles were determined using pulsed-field gel electrophoresis (PFGE). Prevalence data showed that contamination rates varied along the line and were greatest after defeathering and after chilling. Analysis of contamination in relation to serotypes and PFGE profiles found that on some visits the same serotype was present all along the processing line while on other days, additional serotypes were recovered that were not detected earlier on the line, suggesting that the birds harbored more than one serotype of Salmonella or there was cross-contamination occurring during processing. Overall, this study found fluctuations in Salmonella prevalence along a turkey-processing line. Following washing, Salmonella prevalence was significantly reduced, suggesting that washing is critical for Salmonella control in turkey processing and has significant application for controlling Salmonella at the postdefeathering and prechill stages where prevalence increased.

Animals↗

PubMed2005

Prevalence of the Campylobacter multi-drug efflux pump (CmeABC) in Campylobacter spp. Isolated from freshly processed Turkeys.

The prevalence of the Campylobacter multi-drug efflux pump (CmeABC) was evaluated in Campylobacter isolates recovered from freshly processed turkeys at two Midwestern processing plants. A total of 94 Campylobacter isolates recovered from processed turkeys were examined using polymerase chain reaction (PCR) to determine the presence of the multi-drug efflux pump genes cmeA, cmeB, and cmeC. Results from this study found that 51% of all isolates tested were positive for CmeABC. 46.6% of these positive isolates were from plant A and 55.1% from plant B. Differences were observed in the prevalence of individual genes found among Campylobacter isolates from each plant. Additional analysis found that among the isolates positive for CmeABC, 85.5% were identified as C. jejuni and 14.5% identified as C. coli. There was a relatively high occurrence of the Campylobacter multi-drug efflux pump genes in Campylobacter spp. recovered from processed turkeys, however, the presence of the genes could not be significantly linked to antimicrobial resistance observed in the test strains and suggests that the CmeABC genes are only one factor associated with antimicrobial resistance in Campylobacter spp.

Animals↗

PubMed2005

Comparison of Escherichia coli isolates implicated in human urinary tract infection and avian colibacillosis.

Since avian pathogenic Escherichia coli (APEC) and human uropathogenic E. coli (UPEC) may encounter similar challenges when establishing infection in extraintestinal locations, they may share a similar content of virulence genes and capacity to cause disease. In the present study, 524 APEC and 200 UPEC isolates were compared by their content of virulence genes, phylogenetic group, and other traits. The two groups showed substantial overlap in terms of their serogroups, phylogenetic groups and virulence genotypes, including their possession of certain genes associated with large transmissible plasmids of APEC. Based on these results, the propensity of both groups to cause extraintestinal infections, and a well-documented ability of avian E. coli to spread to human beings, the potential for APEC to act as human UPEC or as a reservoir of virulence genes for UPEC should be considered. However, significant differences in the prevalence of the traits occurred across the two groups, suggesting that if APEC are involved in human urinary tract infections, they are not involved in all of them.

Animals↗

PubMed2004

The effect of heart rate, preload, and afterload on the viscoelastic properties of the swine myocardium.

Experiments were performed to test the hypothesis that viscoelastic properties of the swine myocardium are independent of heart rate (HR), preload (PL), and afterload (AL). Left ventricular pressure and aortic flow (AoF) waveforms were recorded in 13 swine. At different paced heart rates, an inferior vena caval occlusion (IVC) was used to reduce PL, then the IVC was released and simultaneously the aorta was clamped to increase AL. Equivalent left ventricular pressure waveform pairs consisting of an ejecting waveform (denoted as LVP) and isovolumic waveform (denoted as hydromotive pressure, HMP) were selected according to specified criteria resulting in 371 equivalent waveform pairs. From the selected waveform pairs and corresponding aortic flow waveforms, the viscoelastic properties (k and epsilon1) were estimated by HMP = LVP + epsilon1 V(EJ) + k x LVP x AoF. Here epsilon1 is the parallel elastance, k is the myocardial friction, and V(EJ) is the integral of AoF over ejection. Next, using k, epsilon1, LVP, and AoF waveforms, HMP was estimated using the equation above. To validate the model, the measured HMP and model-calculated HMP were compared for 371 matched waveform pairs (R2 = 0.97, SEE = 3.7 mmHg). The viscoelastic parameters (k and epsilon1) did not exhibit any clear or predictable dependence on HR, PL, and AL.

Adaptation, Physiological↗

PubMedDate not supplied

Characterizing the APEC pathotype.

The purpose of this study was to compare avian pathogenic Escherichia coli (APEC) isolates to fecal isolates of apparently healthy poultry (avian fecal E. coli or AFEC) by their possession of various traits in order to ascertain whether APEC and AFEC are distinct and if the APEC strains constitute a distinct pathotype. Four hundred and fifty-one APEC and one hundred and four AFEC isolates were examined for possession of traits associated with the virulence of human extraintestinal pathogenic E. coli (ExPEC) as well as APEC. Several of the genes occurred in the majority of APEC and only infrequently in AFEC, including cvaC, iroN, iss, iutA, sitA, tsh, fyuA, irp2, and ompT. Of these genes, several have been found on large plasmids in APEC. Other genes occurred in significantly more APEC than AFEC but did not occur in the majority of APEC. Isolates were also evaluated by serogroup, lactose utilization, and hemolytic reaction. Twenty-nine and a half percent of the APEC and forty-two and three tenths percent of the AFEC were not serogrouped because they were not typeable with standard antisera, typed to multiple serogroups, were rough, autoagglutinated, or were not done. Around 65% of the typeable APEC (205 isolates) and AFEC (41 isolates) were classified into shared serogroups, and about a third of both fell into APEC- (113 isolates) or AFEC- (19 isolates) unique serogroups. Most were able to use lactose. No isolate was hemolytic. Overall, the majority of the APEC isolates surveyed shared a common set of putative virulence genes, many of which have been localized to an APEC plasmid known as pTJ100. This common set of genes may prove useful in defining an APEC pathotype.

Animals↗

PubMedDate not supplied

Complement resistance, as determined by viable count and flow cytometric methods, and its association with the presence of iss and the virulence of avian Escherichia coli.

Previous work in our labs has shown that avian Escherichia coli virulence is correlated with resistance to complement. Also, our studies have revealed that the presence of the increased serum survival gene (iss), known to contribute to the complement resistance and virulence of mammalian E. coli, may predict the virulent nature of an avian E. coli isolate. This relationship warrants further research, but further clarification of the relationship among virulence, complement resistance, and iss sequences requires use of complement susceptibility assays. Such assays, unfortunately, are labor-intensive, expensive, and difficult to perform. In the present study, the results of two complement susceptibility assays for 20 E. coli isolates, 10 incriminated in avian colibacillosis and 10 from the intestinal tracts of apparently healthy birds, were compared in an attempt to determine if flow cytometric analysis was a reasonable alternative to a viable count assay. In addition, the virulence of these isolates for chick embryos was determined, and each isolate was examined for the presence of iss using amplification techniques. The flow cytometric method was found to be repeatable for most isolates, and its results showed moderate agreement with those obtained through viable counts. All intestinal isolates of healthy birds proved avirulent using the embryo lethality assay; however, not all isolates from sick birds were demonstrated to be virulent. Possible explanations of these results include that the methods originally used to isolate these organisms failed to detect the illness-inciting strains or that the virulence of these strains had declined following initial isolation. Additionally, we must consider the possibility that the embryo lethality assay of virulence used here might not be sensitive enough to detect differences between these two groups of isolates. Also, it should be noted that virulence assays, such as the one used here, fail to account for predisposing host or environmental conditions, enabling a less virulent isolate to cause disease under natural conditions. Interestingly, the complement resistance of a strain was significantly associated with its lethality in embryos, and iss-containing isolates were significantly more likely than those lacking iss to be classified as complement-resistant and virulent. Such results, at least for this group of avian E. coli, suggest that there is a compelling but imperfect relationship among complement resistance, virulence, and the presence of iss. These results also suggest that the flow cytometric assay may be a reasonable alternative to the viable count method of determining complement resistance.

Animals↗