Occurrence and Spread of Quinolone-Resistant Escherichia coli on Dairy Farms.

UNLABELLED: Quinolone-resistant Escherichia coli (QREC) is common in feces from young calves, but the prevalence and genetic diversity of QREC in groups of cattle of other ages and the farm environment are unknown. The aims of the study were to obtain knowledge about the occurrence of QREC on dairy farms, the genetic diversity of QREC within and between farms, and how these relate to the number of purchased animals and geographic distances between farms. We analyzed the within-sample prevalence of QREC in individual fecal samples from preweaned dairy calves and postpartum cows and in environmental samples from 23 Swedish dairy farms. The genetic diversity of the QREC isolates on 10 of these farms was assessed. In general, QREC was more prevalent in the dairy farm environment and in postpartum cows if QREC was commonly found in calves than if QREC was rare in calves. In particular, we found more QREC organisms in feed and water troughs and in environments that may come into contact with young calves. Thus, the results suggest that QREC circulates between cattle and the farm environment and that calves are important for the maintenance of QREC. Some genotypes of QREC were widespread both within and between farms, indicating that QREC has spread within the farms and likely also between farms, possibly through purchased animals. Farms that had purchased many animals over the years had greater within-farm diversity than farms with more closed animal populations. Finally, animals on more closely located farms were more likely to share the same genotype than animals on farms located far apart. IMPORTANCE: This study investigates the occurrence of a specific type of antimicrobial-resistant bacterium on dairy farms. It contributes to increased knowledge about the occurrence and spread of these bacteria, and the results pave the way for actions or further studies that could help mitigate the spread of these bacteria on dairy farms and in the community as a whole.

Preventing introduction of livestock associated MRSA in a pig population--benefits, costs, and knowledge gaps from the Swedish perspective.

Antibiotic resistance is a growing concern in human, as well as in veterinary medicine. Part of the problem concerns how to respond to the risk presented by animal reservoirs of resistant bacteria with the potential of spreading to humans. One example is livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA). In countries where LA-MRSA is endemic in the pig population, people in contact with pigs have a higher risk of being colonised with LA-MRSA, and persons from this group are subjected to precautionary measures when visiting health care facilities. In the present study, it is assumed that, if LA-MRSA was introduced to the Swedish pig population, the prevalence in the risk groups would be the same as in Denmark or the Netherlands (two countries with low human prevalence that have implemented measures to detect, trace and isolate human LA-MRSA cases and, therefore, have comprehensive data with good coverage regarding prevalence of LA-MRSA), and that similar interventions would be taken in Swedish health care facilities. It is also assumed that the Swedish pig population is free of MRSA or that the prevalence is very low. We analyse if it would be efficient for Sweden to prevent its introduction by testing imported live breeding pigs. Given that quarantining and testing at import will prevent introduction to the pig population, the study shows that the preventive measures may indeed generate a societal net benefit. Benefits are estimated to be between € 870 720 and € 1 233 511, and costs to € 211 129. Still, due to gaps in knowledge, the results should be confirmed when more information become available.

Incidence of mastitis and bacterial findings at clinical mastitis in Swedish primiparous cows- influence of breed and stage of lactation.

Mastitis is a common disease also among primiparous dairy cows. Identification of the extent and type of problem is important to initiate correct control measures. In Sweden, unique national production and disease databases are available. The main aim of the study was to investigate the occurrence of mastitis, measured by the annual incidence of veterinary-treated clinical mastitis (VTCM) and geometric mean of monthly milk somatic cell count (SCC) recordings in Swedish primiparous cows in relation to older cows during 2002-2006 with emphasis on breed differences. Other aims were to study differences between primiparous and older cows in the distribution of bacterial findings at clinical mastitis, and the occurrence of VTCM and bacterial findings in relation to stage of lactation using data from a Swedish field study performed 2002-2003. Descriptive statistics and univariable analyses were used in the investigations. During 2002-2006 approximately 10% of Swedish primiparous cows experienced VTCM each year, while the geometric mean SCC of Swedish primiparous cows was approximately 65,000 ml(-1). Both parameters were lower than in older cows. Primiparous cows of the Swedish Red (SR) breed had better udder health than cows of the Swedish Holstein (SH) breed. The overall distribution of udder pathogens was similar in primiparous and older cows. In primiparous cows, most VTCM occurred during the first week after calving, and Staphylococcus aureus and Streptococcus dysgalactiae were the most common udder pathogens during this period. Better control measures directed at these infections are warranted around calving to reduce the risk of mastitis in primiparous cows.