Prevalence, antimicrobial resistance and genotyping (AFLP) of thermophilic Campylobacter spp. in broiler flocks and analysis of risk factors for Campylobacter colonisation at flock level

Titelblatt Persönlicher Dank Inhaltsverzeichnis Abkürzungsverzeichnis Einleitung Literaturübersicht Eigene Untersuchungen Ergebnisse Diskussion Schlussfolgerungen Zusammenfassung Summary Quellenverzeichnis Anhang Danksagung, Lebenslauf, SelbstständigkeitserklärungIm Zeitraum von Mai 2004 bis Juli 2005 wurden 279 Masthähnchenherden verschiedener Haltungssysteme auf das Vorkommen von thermophilen Campylobacter spp. beprobt. Hierzu wurde pro Herde der Blinddarmkot von zehn Tieren als Pool- und/oder Einzelproben untersucht. Alle gewonnenen Campylobacter- Isolate wurden durch eine Multiplex- PCR bestätigt. 79 Campylobacter- Isolate wurden durch Mikrodilution auf ihr Verhalten gegenüber acht Antibiotika (-Kombinationen) getestet, 236 Campylobacter- Isolate wurden mittels der AFLP- Analyse feintypisiert. Zuletzt wurden 75 Mastanlagen anhand eines Fragebogens auf mögliche Einflussfaktoren für den Campylobacter- Eintrag in die Herden untersucht. 44% der Herden waren Campylobacter- positiv. C. jejuni wurde mit 77% als dominierende Spezies detektiert, gefolgt von C. coli mit 23%. Das Vorkommen von Campylobacter spp. in den Masthähnchenherden war jahreszeitlichen Schwankung unterworfen mit hohen Prävalenzen in den warmen Sommer- und Herbstmonaten. Die Innerherdenprävalenz variierte von 10% bis 100%. Bei 33% der Herden waren alle zehn Blinddarmpaare positiv. Während in den Campylobacter- positiven Herden aus konventionellen und Louisiana- Ställen vor allem C. jejuni detektiert wurde, war in den Herden aus Freiland- und biologischer Haltung C. coli vorherrschend. Durch Untersuchung von Poolproben wurden 93% der durch Einzeluntersuchung als Campylobacter- positiv befundenen Herden erkannt. Von den 79 untersuchten Campylobacter- Isolaten waren 30% Ampicillin- resistent, 13% resistent gegen Ampicillin in Kombination mit Sulbactam, 10% Ceftazidim- resistent, 41% Ciprofloxacin- und Nalidixinsäure- resistent und 30% Tetrazyklin- resistent. Alle Isolate waren empfindlich gegenüber Gentamicin. Gegenüber Erythromycin waren alle C. jejuni- Isolate sensibel, wohingegen 28% der C. coli- Isolate resistent waren. Es wurden 34 Cluster für 61 C. jejuni- Isolate und 11 Cluster für 18 C. coli- Isolate identifiziert. Dies verdeutlicht die genetische Diversität von Campylobacter spp. bei Mastgeflügel. Das Vorfinden von dominierenden und wiederkehrenden AFLP- Genotypen in aufeinander folgenden Herden verdeutlicht das Bestehen von persistierenden Infektionsquellen in der Umwelt. Das Vorkommen von Campylobacter- negativen Herden nach Campylobacter- positiven Herden zeigt, dass eine Infektion der Herde verhindert werden kann. Die Präsens von verschiedenen Campylobacter- Spezies in einer Herde und in aufeinander folgenden Herden eines Stalles deutet auf verschiedene Infektionsquellen hin und beschreibt die Dynamik der Kolonisation. Anhand der Fragebogenaktion konnten drei Einflussfaktoren für eine Campylobacter- Belastung von Masthähnchenherden erkannt werden: die Haltungsform, die Herdengröße und die Tränkeform. Andere Variablen, wie Hygienemaßnahmen, Alter, Serviceperiode und Wasserquelle hatten keinen signifikanten Einfluss auf die Campylobacter- Prävalenz.From May 2004 to July 2005, 279 broiler flocks of different production types were tested for the presence of thermophilic Campylobacter spp. Of each flock caecal content of ten chickens was tested. All Campylobacter isolates were additionally identified by multiplex- PCR. 79 Campylobacter isolates were tested for susceptibility to eight antimicrobial agents and combinations by microbroth dilution and 236 Campylobacter isolates were genotyped by AFLP- analysis, too. To identify potential risk factors for the presence of Campylobacter spp. at flock level, 75 farms were analysed using farm and flock specific information obtained from questionnaires. Of all investigated broiler flocks Campylobacter spp. was detected in 44%. C. jejuni was the most prevalent species (77%) followed by C. coli (23%). Higher prevalence was mainly associated with summer and fall. Within- flock prevalence varied from 10% to 100%. In 33% of the Campylobacter positive flocks all ten caecal probes were positive. Flocks of conventional and Louisiana broiler houses harboured in most cases C. jejuni, whereas C. coli was the predominant species in flocks from free range or organic farming. Comparing results of pooled and single probes, 93% of Campylobacter positive single probes were detected using pooled probes. Of the 79 (61 C. jejuni, 18 C. coli) chicken isolates 30% (31% bzw. 28%) were ampicillin resistant, 13% (8% bzw. 28%) were resistant against a combination of ampicillin and sulbactam, 10% (8% bzw. 17%) were ceftazidime resistant, 41% (39% bzw. 44%) were ciprofloxacin and nalidixic acid resistant und 30% (30% bzw. 33%) were tetracycline resistant. All strains were susceptible against gentamicin. All C. jejuni strains were susceptible against erythromycin, whereas 28% of C. coli strains were resistant. From 61 C. jejuni- isolates and 18 C. coli isolates 34 AFLP- cluster respectively 11 AFLP- cluster were identified, demonstrating the genetic diversity of Campylobacter spp. isolated from poultry. Dominant and reiterating AFLP- genotypes in successive flocks show the presence of persistent sources of Campylobacter spp. in the environment. Colonisation with sporadic isolates was also found. Campylobacter negative flocks followed Campylobacter positive flocks demonstrating, that it is possible to prevent a Campylobacter infection. Different Campylobacter species within a flock and in successive flocks may be caused by different sources of infections and describe the dynamic of colonisation. Three risk factors for Campylobacter colonisation were identified: production system, flock size and water system

The effect of short-term heat acclimation with a permissive dehydration stimulus in female team sports players

Introduction: Repeated heat exposure can facilitate physiological adaptation to heat during intermittent exercise; however, there is limited information available regarding female cohorts. This has implications on the health and safety guidelines for females during heat exposure. Studies using short-term heat acclimation (STHA) with permissive dehydration have reported improved physiological response and performance during heat exposure but have tended to use male participants. Therefore, the aim of this study was to investigate the efficacy of STHA over 5-days using the controlled hyperthermia technique (with permissive dehydration), on an intermittent heat stress test (HST), using a female cohort and controlling for menstrual cycle.Methods: Eight healthy, active, moderately trained females (mean [SD]; age 22.6 [3.0] y; height 166.2 [6.0] cm; body mass 62.3 [9.0] kg; VO2 max 43.2 [8.2] mL.kg-1.min-1). The HST (31.0˚C, 50% RH) consisted of 9x5min (45 mins) of intermittent exercise (individualised standing, walking, jogging, low-, medium-, and high-intensity running on a motorised treadmill) finishing with a 6s maximal sprint on a cycle ergometer. The exercise intensities were adapted from the match-play dynamics of female collegiate football players. Participants completed two HSTs (HST1 and HST2), separated by one week, with no STHA, as a control (C) trial. This was followed by 90 mins dehydration (no fluid), heat acclimation for 5 consecutive days (39.5˚C, 60% RH), using the controlled hyperthermia technique (rectal temperature [Tre] 38.5˚C). Participants completed a final HST (HST3), within one week of the STHA. The HST2 and HST3 trials were in the same week of each participant’s menstrual phase determined by self-reported menstrual cycle and plasma 17β-estradiol.Results: Post (HST3) vs. Pre- (HST2) STHA, showed a reduced rectal temperature (Tre) at 45-min by 0.20˚C (95%CI: -0.31 to -0.05˚C; p = 0.01; d = 1.13); mean skin temperature ( sk T ) (-0.47; -0.82 to -0.12°C; P = 0.02; d = 1.06) and mean body temperature ( b T ) (-0.21; -0.31 to -0.11°C; P = 0.001; d = 1.28). There was limited change (P > 0.05) for these measures in the HST1 vs. HST2 C trial. Resting cardiac frequency decreased by 11 b.min-1 (-16 to -5 b.min-1; P = 0.004; d = 0.81) and by 3 b.min-1 at 45-min (-8 to 0 b.min-1; P = 0.07; d = 0.65). There was an increase in percentage plasma volume (%PV) change post-STHA by 8.65% (-1.21 to 18.51%; P = 0.007; d = 1.26) but limited change in C (P > 0.05). There was an increase in mean average power (MAvP) across all 9 sprints by 41W (3 to 80W; P = 0.04; d = 0.18) but limited change in C (P > 0.05).Discussion and conclusion: Short-term heat acclimation (5 days), with permissive dehydration, using the controlled-hyperthermia technique leads to physiological adaptation during intermittent exercise in the heat, in moderately trained females when controlling for menstrual cycle

Artificial Intelligence: Threat or ‘colleague’? Exploring managers’ perceptions of AI in organisations

COVID-19 has brought organizations to reinvent their businesses due to the greater need: employees and customers safety. This paper explores managers’ perceptions of the adoption of AI in the workplace. It considers how they construct new technology adoption and the potential it has to be integrated into work practices. This research in progress paper contributes to the information systems literature by taking a qualitative approach to better understand managers’ perspectives of AI and the contextual factors that influence their decision to adopt. Semi-structured interviews were used to study managers’ perceptions and experiences through which AI might have been considered supportive or a job threat. Overall, pre-liminary findings showed that managers have dealt with technologies that have helped them to perform their managerial duties. However, most of them have displayed doubts related to trust and interpersonal complexity. Interviews unanimously stated that AI cannot (completely) replace managers, but it is of interest how they also highlighted the uncertainty of AI and its future. Future research will further explore the complexities of AI adoption using Cultural-Historical Activity Theory as a framework to understand the transformation of organisational activities through socio-technological practices

Effectiveness of a six-week high-intensity interval training programme on cardiometabolic markers in sedentary males

High-intensity interval training (HIT) has been proposed as an effective, time efficient strategy to elicit similar cardiometabolic health benefits as traditional moderate-intensity endurance training. This is an important consideration as "lack of time" is a common cited barrier to regular physical activity