Reto Straub

Influences of endurance training on the ultrastructural composition of the different muscle fiber types in humans

AbstractTo investigate changes in the ultrastructure of the different muscle fiber types induced by endurance training ten sedentary subjects (five women and five men) were exercised on bicycle ergometers 5 times a week for 30 min. After 6 weeks of training there were significant changes in

Transmission of opportunistic pathogens in a veterinary teaching hospital

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Effects of genetic and environmental factors on chronic lower airway disease in horses

(+14%), in the percentage of type I (+12%) and type IIB fibers (−24%) as well as in the volume densities of mitochondria. The latter increased 35% in type I, 55% in type IIA and 35% in type IIB fibers. The relative increase in subsarcolemmal mitochondria was larger than in interfibrillar mitochondria in all fiber types. There was also a significant increase in the volume density of intracellular lipid in type II fibres. It is concluded that high intensity endurance training leads to an enhancement of the oxidative capacity in all muscle fiber types.

Antibiotic‐induced expression of a cryptic cpb2 gene in equine β2‐toxigenic Clostridium perfringens

ABSTRACT Because of the frequency of multiple antibiotic resistance, Staphylococcus species often represent a challenge in incisional infections of horses undergoing colic surgery. To investigate the evolution of antibiotic resistance patterns before and after preventative peri- and postoperative penicillin treatment, staphylococci were isolated from skin and wound samples at different times during hospitalization. Most staphylococci were normal skin commensals and belonged to the common coagulase-negative group. In some cases they turned out to be opportunistic pathogens present in wound infections. MICs were determined for 12 antibiotics, and antibiotic resistance genes were detected by microarray. At hospital admission, horses harbored staphylococci that were susceptible to antibiotics or resistant to one group of drugs, mainly due to the presence of new variants of the methicillin and macrolide resistance genes mecA and mph(C), respectively. After 3 days, the percentage of Staphylococcus isolates displaying antibiotic resistance, as well as the number of resistance genes per isolate, increased moderately in hospitalized horses without surgery or penicillin treatment but dramatically in hospitalized horses after colic surgery as well as penicillin treatment. Staphylococcus species displaying multiple resistance were found to harbor mainly genes conferring resistance to β-lactams (mecA and blaZ), aminoglycosides [str and aac(6′)-Ie-aph(2′)-Ia], and trimethoprim [dfr(A) and dfr(D)]. Additional genes conferring resistance to macrolides [mph(C), erm(C), and erm(B)], tetracycline [tet(K) and tet(M)], chloramphenicol [cat(pC221) and cat(pC223)], and streptothricin (sat4) appeared in several strains. Hospitalization and preventive penicillin use were shown to act as selection agents for multidrug-resistant commensal staphylococcal flora.

Nicoletella semolina gen. nov., sp. nov., a New Member of Pasteurellaceae Isolated from Horses with Airway Disease

Acinetobacter baumannii, Enterococcus faecalis, Enterococcus faecium, and Staphylococcus intermedius isolates from infected surgical wounds and other types of infections in a veterinary teaching hospital were typed by pulsed field gel electrophoresis. A first cluster of infections with a multiresistant A. baumannii strain was observed in dogs and cats in 1998-1999. This strain disappeared after cleaning and disinfection of the companion animals intensive care unit. It was followed in 2000 by a second multiresistant strain, which caused another cluster of infections and was also transmitted to a patient in the nearby horse clinic. Transmission of a multiresistant E. faecium strain between two cats with surgical wound infections was also observed during the same period. No multiresistant S. intermedius strain was observed during this time and transmission of this organism between patients did not seem to occur. The present study demonstrates the potential for hospital nosocomial resistance problems in veterinary medicine similar to those encountered in human medicine. The results suggest that the epidemiology of nosocomial infections with A. baumannii and E. faecium may differ from that of S. intermedius infections and that preventive measures may have to be adapted to the problem organism.

In vitro allergy tests compared to intradermal testing in horses with recurrent airway obstruction.

REASONS FOR PERFORMING STUDY Horses housed in conventional stable environments are exposed to high dust loads. Long-term exposure to inhaled dust may lead to subclinical airway disease. HYPOTHESES Airway inflammation and mucus accumulation are 1) common in asymptomatic well-performing sport horses, 2) increased in older compared to younger individuals and 3) correlated. METHODS Mucus quantity and quality (endoscopic scoring) and BALF differential cytology were assessed in 13 younger horses (mean age 5 years) and 13 older horses (mean age 15 years), which had no historical or clinical evidence of lower airway disease, were performing well and were housed permanently in a conventional stable environment. RESULTS 1) Airway inflammation and/or mucus accumulation were very common. All sport horses showed evidence of subclinical inflammatory airway disease (IAD). 2) Older horses, having been exposed for 10 more years to a conventional stable environment, did not show increased subclinical airway inflammation or mucus accumulation. The only differences between the age groups were increased BALF total and lymphocyte cell counts in the younger horses. 3) Mucus quantity and quality scores were not significantly correlated with each other or with BALF neutrophil percentages and absolute numbers. CONCLUSIONS Although clinically healthy and performing well, all of the examined horses housed in a conventional stable environment showed evidence of IAD. The degree of IAD was not increased in older horses that had not developed clinical signs. POTENTIAL RELEVANCE The effect of subclinical degrees of IAD on performance in dressage and show jumping should be investigated further to better understand the clinical significance of IAD in sport horses.

Clostridium Difficile Associated with Typhlocolitis in an Adult Horse

BACKGROUND Environment and genetics influence the manifestation of recurrent airway obstruction (RAO), but the associations of specific factors with mild, moderate, and severe clinical signs are unknown. HYPOTHESIS We hypothesized that sire, feed, bedding, time outdoors, sex, and age are associated with clinical manifestations of mild, moderate, and severe lower airway disease. ANIMALS Direct offspring of 2 RAO-affected Warmblood stallions (F1S1, n = 172; F1S2, n = 135); maternal half-siblings of F1S1 (mHSS1, n = 66); and an age-matched, randomly chosen control group (CG, n = 33). METHODS A standardized questionnaire was used to assess potential risk factors and to establish a horse owner assessed respiratory signs index (HOARSI 1-4, from healthy to severe) according to clinical signs of lower airway disease. RESULTS More F1S1 and F1S2 horses showed moderate to severe clinical signs (HOARSI 3 and HOARSI 4 combined, 29.6 and 27.3%, respectively) compared with CG and mHSS1 horses (9.1 and 6.2%, respectively; contingency table overall test, P < .001). Sire, hay feeding, and age (in decreasing order of strength) were associated with more severe clinical signs (higher HOARSI), more frequent coughing, and nasal discharge. CONCLUSIONS AND CLINICAL RELEVANCE There is a genetic predisposition and lesser but also marked effects of hay feeding and age on the manifestation of moderate to severe clinical signs, most markedly on coughing frequency. In contrast, mild clinical signs were not associated with sire or hay feeding in our populations.

Lethal toxin of Clostridium sordellii is associated with fatal equine atypical myopathy

The cpb2 gene of β2‐toxigenic Clostridium perfringens isolated from horses, cattle, sheep, human and pigs was sequenced. The cpb2 gene of equine and other non‐porcine isolates differed from porcine isolates by the absence of an adenine in a poly A tract immediately downstream of the start codon in all non‐porcine C. perfringens strains. This deletion involved formation of a cryptic gene harbouring a premature stop codon after only nine amino acid codons, while the full β2‐toxin protein consists of 265 amino acids. Immunoblots carried out with antibodies directed against a recombinant β2‐toxin showed the absence of expression of the β2‐toxin in equine and the other non‐porcine strains under standard culture conditions. However, treatment of C. perfringens with the aminoglycosides gentamicin or streptomycin was able to induce expression of the cpb2 gene in a representative equine strain of this group, presumably by frameshifting. The presence of the β2‐toxin was revealed by immunohistology in tissue samples of small and large intestine from horses with severe typhlocolitis that had been treated before with gentamicin. This result may explain the finding that antibiotic treatment of horses affected by β2‐toxigenic C. perfringens leads to a more accentuated and fatal progression of equine typhlocolitis. Clinical observations show a reduced appearance of strong typhlocolitis in horses with intestinal complications admitted to hospital care since the standard use of gentamicin has been abandoned. This is the first report on expression of a bacterial toxin gene by antibiotic‐induced ribosomal frameshifting.