Antimicrobial resistance among enteric organisms in food animals varied among countries, particularly for older antimicrobials, but clinical resistance to essential compounds used to treat disease in humans was generally zero or low. In the absence of clinical resistance to newer compounds in E. coli and Salmonella, the apparent decreased susceptibility should be monitored carefully.

Resistance patterns varied widely depending on bacterial species, antibiotics, hosts and region. Resistance varied among countries, particularly for older antimicrobials, but clinical resistance to newer antibiotics used to treat foodborne disease in humans was generally very low. In the absence of resistance to newer compounds in E. coli and Salmonella, the apparent decreased susceptibility should be monitored.

BOVINE respiratory disease (BRD) in calves is a multifactorial disease complex involving interactions between a wide range of pathogens, immune status and environmental stresses. The most common non-viral pathogens involved include Mannheimia (Pasteurella) haemolytica, Pasteurella multocida, Histophilus somni (Haemophilus somnus) and Mycoplasma bovis (Bryson 2000, Donachie 2000, Nicholas and Ayling 2003. To ensure effective treatment of disease, veterinarians and researchers regularly need to determine the presence and antimicrobial sensitivity of pathogenic bacteria during outbreaks of BRD on farms and in clinical studies. Ideally, the technique should be quick and simple, and involve minimal stress for the calf. The ability to sample entire groups of animals and monitor infection status over time is also valuable and would be facilitated by the use of a simple nasopharyngeal swab method compared with the more difficult and hazardous procedures such as transtracheal aspiration or bronchoalveolar washings. This short communication describes the use of a deep nasopharyngeal swab technique to predict the presence of specific pathogenic species in the lower respiratory tract. Isolates were tested to determine their sensitivity to tulathromycin, a member of the newly developed triamilide subclass of macrolide derivatives (Letavic and others 2002). The study was conducted under veterinary supervision and in accordance with good clinical practice guidelines (Anon 2000), and the husbandry of all animals was in accordance with local animal welfare requirements and legislation.Thirty-seven beef calves, approximately four to six months of age, were group-housed on straw in an open-fronted barn in France, when a natural outbreak of BRD occurred. The criteria for enrolment in the study were those usually applied for the initiation of antimicrobial therapy, that is, the presence of clinical signs of BRD as defined by an elevated rectal temperature (≥40°C), together with abnormal respiratory signs (increased rate and/or abnormal character) and a depressed demeanour. Within the group, 20 animals met the criteria and were enrolled, which ensured a similar severity of disease among all the enrolled animals. The remaining calves were not enrolled but remained on the premises and were treated later for BRD with appropriate medication, if required, including antimicrobials.Nasopharyngeal samples were collected from each animal enrolled in the study, using sterile equine uterine culture swabs, 76 cm long, guarded by an external sheath and with the swab tip protected by a gelatine plug (Equi-Vet; Krusse). The animal's head was restrained by an assistant and the external nares were wiped clean of discharges. The distance between the nostril and the medial canthus of the eye was estimated and marked by the operator gripping the swab sheath at this point. The guarded, sheathed swab was then inserted into the nasal cavity as far as permitted by the position of the hand holding the swab. The tip of the swab was extruded beyond the sheath a...

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Susceptibility testing of tulathromycin: interpretative breakpoints and susceptibility of field isolates.

In vitro minimum inhibitory concentrations were determined for 21 antimicrobials against 41 isolates of Mycoplasma mycoides subsp. mycoides small-colony type, the cause of contagious bovine pleuropneumonia. Of the antimicrobials used most widely in Africa, oxytetracycline and tilmicosin were effective, while the isolates were resistant to tylosin. These results provide a baseline for monitoring antimicrobial resistance.

SummaryIn 3 consecutive experiments, each using 20 cows, the application of Escherichia coli to teat ends after milking led to high rates of intramammary infection. These infections were not prevented by disinfection of the teats before milking, by the installation of shields in the short milk tubes of the milking cluster or by the use of an individual quarter milking cluster. Rates of infection were significantly lower when teat contamination was applied 1 h before milking compared to contamination applied immediately after milking.These data suggest that penetration of the teat duct by the E. coli occurred in the period between contamination and milking. Seventy four percent of infections occurred in hindquarters and there were variations in the susceptibility of cows to infection.

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