Strategies of exploitation of mammalian reservoirs by Bartonella species

ABSTRACT: Numerous mammal species, including domestic and wild animals such as ruminants, dogs, cats and rodents, as well as humans, serve as reservoir hosts for various Bartonella species. Some of those species that exploit non-human mammals as reservoir hosts have zoonotic potential. Our understanding of interactions between bartonellae and reservoir hosts has been greatly improved by the development of animal models for infection and the use of molecular tools allowing large scale mutagenesis of Bartonella species. By reviewing and combining the results of these and other approaches we can obtain a comprehensive insight into the molecular interactions that underlie the exploitation of reservoir hosts by Bartonella species, particularly the well-studied interactions with vascular endothelial cells and erythrocytes.     

Radiographic findings of the medial humeral epicondyle in 200 canine elbow joints

Objectives: To determine the frequency and radiographic aspect of medial humeral epicondylar lesions as a primary or concomitant finding and to evaluate the association with osteoarthritis. Methods: Medical records of dogs diagnosed with elbow lameness were reviewed. Inclusion criteria for this study were a complete clinical examination, a complete set of digital radiographs and a final diagnosis made by computed tomography or magnetic resonance imaging and arthroscopy. Changes of the medial humeral epicondyle were recorded and correlated with the radiographic osteoarthritis and final diagnosis. Results: Eighty of the 200 elbows showed changes of the medial humeral epicondyle. In 12 of these 80 elbows, changes of the medial epicondyle were the only findings within the joint, and these elbows were diagnosed with primary flexor enthesopathy. In the remaining 68 elbows, other concomitant elbow pathologies were found. In those cases of concomitant epicondylar changes, high grades of osteoarthritis were recorded, while most elbows with primary flexor enthesopathy showed a low grade of osteoarthritis. Clinical significance: Changes of the medial humeral epicondyle are often considered clinically unimportant and are regarded as an expression of osteoarthritis. This study showed the relatively frequent presence of epicondylar changes of which the majority were considered concomitant to a primary elbow problem. If changes of the medial humeral epicondyle are the only pathologic finding (primary flexor enthesopathy) they should be considered as the cause of lameness and not as a sign of osteoarthritis.     

Progesterone production in mares and echographic evaluation of the corpora lutea formed after follicular aspiration

Ultrasound‐guided follicular aspiration was performed in 26 Criollo crossbred mares, followed by the evaluation of ultrasonographic images of the Corpus luteum (CL) that was formed after puncture of follicles of different diameters (Group 25–29 mm; Group 30–35 mm and Group >35 mm). Serum progesterone (P₄) concentrations were measured to determine CL function. The size of the CL was measured and the CL was classified based on the following echoscore: 1– anechoic tissue; 2– poorly defined luteal structure with low echogenicity; 3– echogenicity analogous to a luteal structure. The proportion of aspirated follicles that formed a functional CL (based on P₄ concentration) 8 days after aspiration was 57.1% (4/7; CL size 25–29 mm), 75.0% (6/8; CL size 30–35 mm) and 72.7% (8/11; CL size >35 mm), respectively (p > 0.05). The echographic scores of aspirated follicles (indicating the presence or absence of a CL) were consistent with serum P₄ concentrations (p < 0.0001). Of 26 aspirations, 18 resulted in luteal function confirmed by increased progesterone concentrations ([P₄] > 1.0 ng/ml); 17 of these mares (94.4%) had an echoscore (2–3) compatible with luteinization (p = 0.0372). Eight days after aspiration, serum [P₄] > 2.0 ng/ml was associated with high (p = 0.0056) CL echoscore (3) in 15 of 17 mares (88.2%). The echoscore used in this study was valuable as a screening test to detect the presence of a functional CL after aspiration. An echoscore of 3 served as a practical and efficient method to confirm luteinization.     

Diseases Associated with Thrombosis

Coagulation abnormalities are commonly encountered in critical illness. Traditionally, clinically relevant coagulation disorders have consisted mostly of bleeding associated with advanced stages of disseminated intravascular coagulation or toxin ingestion. However, advances in critical care have highlighted hypercoagulability as a clinically relevant state that must be recognized and treated to optimize the chances of a positive outcome. Retrospective studies of dogs with confirmed thrombosis in varying locations have identified populations most likely to experience hypercoagulable states. Diseases most frequently complicated by thrombosis include immune-mediated disease, neoplasia, systemic inflammation and sepsis, cardiac disease, protein-losing states, and infectious diseases. In this report, the existing retrospective studies will be discussed along with a review of specific disease processes that predispose to a hypercoagulable state. Studies targeting those populations most at risk for thrombotic complications are necessary for better understanding the need for prophylactic anticoagulant therapy.     

Prevalence of methicillin-resistant Staphylococci on a farm: staff can harbour MRS when animals do not

The aim of this work was to establish the prevalence of methicillin-resistant Staphylococci (MRS) in the animals and staff of a teaching and research farm. Samples of dairy cattle (36), beef cattle (26), sheep (19), horses (21), pigs (23), goats (23) and humans (13) were collected and screened for the presence of MRS. The detection of mecA gene was performed by PCR to determine the resistance of the samples to methicillin. Antimicrobial-resistance testing to penicillin, meropenem, ceftriaxone, cephalothin, oxacillin, levofloxacin, enrofloxacin, chloramphenicol, ciprofloxacin, gentamicin, clindamycin, erytromycin, linezolid, sulfamethoxazole/trimethoprim, tetracycline, doxycycline and vancomycin was performed on the mecA+ isolates. From the 161 samples, four methicillin-resistant coagulase-negative Staphylococci (MRCoNS) were isolated from human beings (31%), whereas none was isolated from animals (0%). No methicillin-resistant Staphylococcus aureus (MRSA) were isolated. All of the MRCoNS isolates from this work presented different antimicrobial resistance patterns. MRCoNS may be present in humans associated with animals while not present in the animals. Selective pressure outside of the farm and a lack of MRCoNS transmission between humans and animals may be responsible for this lack of correlation.     

Evaluation of Nociception,Sedation, and Cardiorespiratory Effects of a Constant Rate Infusion of Xylazine Alone or in Combination with Lidocaine in Horses

This study aimed to evaluate the effects of a constant rate infusion (CRI) of xylazine or xylazine in combination with lidocaine on nociception, sedation, and physiologic values in horses. Six horses were given intravenous (IV) administration of a loading dose (LD) of 0.55 mg/kg of xylazine followed by a CRI of 1.1 mg/kg/hr. The horses were randomly assigned to receive three treatments, on different occasions, administered 10 minutes after initiation of the xylazine CRI, as follows: control, physiologic saline; lidocaine low CRI (LLCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.025 mg/kg/min); and lidocaine high CRI (LHCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.05 mg/kg/min). A blinded observer assessed objective and subjective data for 50 minutes during the CRIs. In all treatments, heart and respiratory rates decreased, end-tidal carbon dioxide concentration increased, and moderate to intense sedation was observed, but no significant treatment effect was detected in these variables. Ataxia was significantly higher in LHCRI than in the control treatment at 20 minutes of infusion. Compared with baseline values, nociceptive threshold increased to as much as 79% in the control, 190% in LLCRI, and 158% in LHCRI. Nociceptive threshold was significantly higher in LLCRI (at 10 and 50 minutes) and in LHCRI (at 30 minutes) than in the control treatment. The combination of CRIs of lidocaine with xylazine produced greater increases in nociceptive threshold compared with xylazine alone. The effects of xylazine on sedation and cardiorespiratory variables were not enhanced by the coadministration of lidocaine. The potential to increase ataxia may contraindicate the clinical use of LHCRI, in combination with xylazine, in standing horses.     

Quantification of transmission of livestock-associated methicillin resistant Staphylococcus aureus in pigs

Antimicrobial resistance in pigs becomes a public health issue when resistant organisms transfer from pigs to humans. Pigs are a large reservoir for livestock-associated (LA-)MRSA and people in contact with pigs are at risk for infection with LA-MRSA. Transmission and persistence of LA-MRSA within a pig population contributes to the maintenance of this zoonotic reservoir. Current knowledge on colonization and transmission of LA-MRSA in pigs is limited and mainly based on observational field surveys. Two experiments were performed to colonize pigs and quantify transmission of LA-MRSA between pigs. In the first experiment, colonization of six-week old piglets failed after intranasal inoculation, confirming the complexity of MRSA-colonization. In the second experiment, naive pigs got colonized after exposure to orally inoculated pigs. Subsequently, these contact-infected pigs transmitted MRSA to a new group of naive pigs. The reproduction ratio, R(0), was estimated with a SIS-model to quantify transmission between the first and second contact pigs as this resembles more the natural transmission. Two scenarios were evaluated, with different assumptions regarding infection status of individual pigs. R(0) varied between 3.7 and 4.3 and was significantly above 1, indicating a high probability of persistence of LA-MRSA, even without antimicrobial use.     

Evaluation in broilers of the probiotic properties of Pichia pastoris and a recombinant P. pastoris containing the Clostridium perfringens alpha toxin gene

The probiotic properties of Pichia pastoris and of a recombinant P. pastoris containing the Clostridium perfringens alpha toxin gene were evaluated in broilers. One-day-old chicks randomly divided in four groups were fed with commercial feed devoid of antibacterials. The control group (1) received plain food, while the other groups were supplemented with either P. pastoris (2), the recombinant P. pastoris (3) or Bacillus cereus var. Toyoi (4). At day 49, live weights, feed efficiency and seroconversions were higher (P<0.05) in the supplemented groups than in the control groups. Group 3 showed the best results, while group 2 had lower weight gain than groups 3 and 4 although food conversion was better than in group 4. Seroconversions were not different (P>0.05) among the supplemented groups. Adverse reactions were not observed in histopathologic evaluation. We concluded that P. pastoris and the recombinant P. pastoris could be used as probiotics in broilers.