A nationwide survey was conducted in Finland to estimate prevalence of bovine mastitis, distribution of mastitis pathogens, and in vitro antimicrobial susceptibility of different mastitis pathogens. In total, 12,661 quarter milk samples were collected from 3282 dairy cows at 216 farms. These were randomly selected from a database covering all Finnish dairy farms. Quarter milk samples collected by the dairy advisors were submitted for somatic cell counting, bacteriological examination, and testing for antimicrobial susceptibility. If the milk SCC of a cow or of a quarter exceeded 300,000/mL, the cow was defined as having mastitis. The results were compared with those of a previous survey done in 1995. The prevalence of mastitis continued to decrease from 38% in 1995 to 31% in 2001. Compared with the study from 1995, the number of quarters with bacterial growth in 2001 increased significantly from 21.0 to 33.5%. This mainly resulted from increased prevalence of Corynebacterium bovis. Coagulase-negative staphylococci remained the most common bacterial group, comprising almost one-half of the pathogens isolated, whereas the relative number of Staphylococcus aureus isolations decreased from the time of the previous study. According to in vitro antimicrobial susceptibility testing, the enterococci demonstrated the highest level of resistance. Compared with the other Nordic countries, penicillin resistance among the staphylococci was still at a relatively high level in Finland (52.1 and 32.0% for Staphylococcus aureus and coagulase-negative staphylococci, respectively). Streptococci isolated from mastitis were very susceptible to beta-lactam antibiotics, as also found in the previous survey in 1995.

Intramammary infection (IMI), also known as mastitis, is the most frequently occurring and economically the most important infectious disease in dairy cattle. This study provides a validation of the analytical specificity and sensitivity of a real-time PCR-based assay that identifies 11 major pathogen species or species groups responsible for IMI, and a gene coding for staphylococcal beta-lactamase production (penicillin resistance). Altogether, 643 culture isolates originating from clinical bovine mastitis, human, and companion animal samples were analyzed using the assay. The isolates represented 83 different species, groups, or families, and originated from 6 countries in Europe and North America. The analytical specificity and sensitivity of the assay was 100% in bacterial and beta-lactamase identification across all isolates originating from bovine mastitis (n = 454). When considering the entire culture collection (including also the isolates originating from human and companion animal samples), 4 Streptococcus pyogenes, 1 Streptococcus salivarius, and 1 Streptococcus sanguis strain of human origin were identified as Streptococcus uberis, and 3 Shigella spp. strains were identified as Escherichia coli, decreasing specificity to 99% in Strep. uberis and to 99.5% in E. coli. These false-positive results were confirmed by sequencing of the 16S rRNA gene. Specificity and sensitivity remained at 100% for all other bacterial targets across the entire culture collection. In conclusion, the real-time PCR assay shows excellent analytical accuracy and holds much promise for use in routine bovine IMI testing programs. This study provides the basis for evaluating the assay's diagnostic performance against the conventional bacterial culture method in clinical field trials using mastitis milk samples.

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Penicillin resistance identification tests are important in veterinary medicine. Six enzyme assays and a PCR test were compared for the detection of ␤-lactamase production or the ␤-lactamase gene in 175 staphylococcal isolates. We conclude that the PCR test and two nitrocefin-based assays can be recommended for routine clinical use.Staphylococci are common causes of a wide variety of diseases in animals. The most important staphylococcal pathogens include Staphylococcus aureus and coagulase-negative staphylococci (CNS), which cause bovine mastitis; Staphylococcus intermedius, which causes otitis externa and pyoderma in dogs; and Staphylococcus hyicus, which is responsible for exudative dermatitis in pigs (see, e.g., references 4, 8, and 9).In veterinary medicine, penicillin is recommended as the first choice for bacteria that are inherently sensitive to it. In contrast to human isolates (3), the prevalence of penicillin resistance in staphylococci causing animal diseases can be relatively low (1) and is most commonly due to the blaZ gene, which encodes the production of ␤-lactamase (7). The aim of this study was to compare the performance and evaluate the practicality of various alternative methods for the determination of ␤-lactamase production or the ␤-lactamase gene in staphylococci.A total of 175 staphylococcal isolates were used in this study, including 95 Staphylococcus aureus, 50 Staphylococcus intermedius, and 30 CNS isolates (Table 1). S. aureus and CNS isolates were taken from mastitis samples from cows. S. intermedius isolates were obtained from clinical samples of dogs. The CNS included eight S. epidermidis, five S. xylosus, four S. chromogenes, three S. cohnii, three S. haemolyticus, two S. hyicus, two S. saprophyticus, two S. simulans, and one S. warneri isolate. Hence, the number of CNS available for this study was relatively low, and results with them should be considered preliminary.