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Journal of Dairy Science Jun 2018Diagnosis of bovine intramammary infection (IMI) has traditionally been based on bacterial culture, but currently IMI can also be detected with DNA based methods, such...
Diagnosis of bovine intramammary infection (IMI) has traditionally been based on bacterial culture, but currently IMI can also be detected with DNA based methods, such as multiplex real-time PCR. The aim of this study was to describe the elimination of bacteria in experimentally induced IMI on the quarter level, using conventional bacterial culture (BC) and multiplex real-time PCR. Two coagulase-negative staphylococcal species, Staphylococcus epidermidis and Staphylococcus simulans, were experimentally inoculated into 14 healthy quarters of 8 dairy cows during 4 consecutive study periods. Intramammary infections were followed with 20 milk samplings per each quarter. Milk somatic cell count was monitored to evaluate the inflammation process in the quarters. Four quarters cured spontaneously during the study period according to the culture. The PCR detected staphylococcal DNA from these quarters for several days after they were defined as cured in BC. Agreement between BC and PCR results varied from substantial to almost perfect agreement for the first 36 h postchallenge, decreasing to moderate levels toward the end of the sampling period. Based on this study, we recommend collecting possible follow-up samples to assess the bacteriological cure from IMI not until 2 to 3 wk after the onset of mastitis or after the quarter milk somatic cell count has normalized when PCR is used.
Topics: Animals; Cattle; Cell Count; Female; Mastitis, Bovine; Milk; Real-Time Polymerase Chain Reaction; Staphylococcal Infections; Staphylococcus
PubMed: 29573801
DOI: 10.3168/jds.2017-13939 -
Journal of Dairy Science May 2024There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the... (Observational Study)
Observational Study
There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the prevalence of IMI caused by different microorganisms in lactating Jersey cattle and evaluate the associations among microbes and somatic cell count (SCC) and persistence of IMI. This prospective, observational, longitudinal study included lactating Jersey cows (n = 753) from 4 farms within a 415 km radius of Columbia, Missouri. Quarter foremilk samples were aseptically collected monthly for 3 consecutive months. Microorganisms were identified using aerobic milk culture and MALDI-TOF mass spectrometry. A commercial laboratory measured SCC using flow cytometry. Milk culture results were used to classify single microorganism infections as persistent (same microorganism species identified at first sampling and one other sampling) or nonpersistent infection. Mixed models were built to evaluate the associations between IMI status and SCC natural logarithm (lnSCC), as well as persistence and lnSCC. Overall, staphylococci were the most commonly isolated microorganisms among the 7,370 quarter-level milk samples collected. Median prevalence (using all 3 samplings) of specific microbes varied among farms; however, Staphylococcus chromogenes was a common species found at all farms. The most common microbial species that persisted were Staph. chromogenes, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus uberis. Streptococcus dysgalactiae and Staph. aureus were the IMI associated with the most inflammation based on lnSCC. The small number of herds included in this study with the large variation in herd type limits the generalizability of the data. However, results of this study seem to be similar to those of previous studies in other breeds, suggesting management factors are more important than breed-specific differences when evaluating causes of IMI and associated subclinical mastitis.
Topics: Cattle; Animals; Female; Milk; Lactation; Prevalence; Longitudinal Studies; Prospective Studies; Mastitis, Bovine; Staphylococcal Infections; Staphylococcus aureus; Cell Count; Cattle Diseases
PubMed: 37949401
DOI: 10.3168/jds.2023-23848