Diversity of Staphylococcus aureus enterotoxin genes and its potential impact on severity of mastitis in dairy cows.

Staphylococcus aureus enterotoxins (SEs) can lead to food poisoning and appear to play a pivotal role in the development and severity of mastitis. This study aimed to evaluate whether the presence and diversity of S. aureus Enterotoxin genes mastitis-causing are associated with the development and severity of mastitis in dairy cows.

Economic impact of staphylococcal and mammaliicoccal subclinical mastitis in dairy herds from Northeast Brazil.

This study aimed to assess the impact of S. aureus as well as Non-aureus Staphylococci and Mammaliicocci (NASM) subclinical mastitis-causing in the economic return in dairy herds. Data were gathered from the databases of five dairy herds located in the Agreste region of Pernambuco state, Northeastern Brazil, over a period of three consecutive months.

Biofilm Formation and Antimicrobial Resistance of and Isolates from Bovine Mastitis.

This study aimed to assess (a) the biofilm producer ability and antimicrobial resistance profiles of () and () isolated from cows with clinical mastitis (CM) and subclinical mastitis (SCM), and (b) the association between biofilm producer ability and antimicrobial resistance. We isolated a total of 197 strains (SCM = 111, CM = 86) and 119 strains (SCM = 15, CM = 104) from milk samples obtained from 316 cows distributed in 24 dairy herds. Biofilm-forming ability was assessed using the microplate method, while antimicrobial susceptibility was determined using the disk diffusion method against 13 antimicrobials.

Comparison of Minimum Inhibitory Concentrations of Selected Antimicrobials for Non-Aureus , , , and Isolated from Milk Samples of Cows with Clinical Mastitis.

The objective of this study was to compare the minimum inhibitory concentrations of antimicrobials included in a commercial broth microdilution panel among Gram-positive pathogens that caused non-severe clinical mastitis on three Michigan dairy farms. Duplicate quarter milk samples were collected from eligible quarters of cows enrolled in a randomized clinical trial, cultured in a university laboratory, and identified using MALDI-TOF. Etiologies were grouped by genus as species (n = 11), species (n = 44), non-aureus species (n = 39), or species (n = 25).

Apparent prevalence and selected risk factors of methicillin-resistant and non- staphylococci and mammaliicocci in bulk tank milk of dairy herds in Indiana, Ohio, and Michigan.

The purpose of this study was to determine the apparent prevalence and risk factors of methicillin-resistant and non- staphylococci and mammaliicocci (NASM) in bulk tank milk (BTM) obtained from 300 dairy farms that belong to a cooperative collecting milk from Indiana, Michigan, and Ohio. Dairy field personnel recorded information about selected farm level risk factors and collected and froze BTM samples (n = 300) that were sent to Michigan State University researchers. Milk samples were thawed at room temperature and pre-enriched by adding 1 to 4 mL of Mueller-Hinton broth supplemented with 6.

MALDI-TOF bacterial subtyping for rapid detection of biomarkers in Staphylococcus aureus from subclinical bovine mastitis.

Aims: This study aimed to evaluate matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial subtyping for the rapid detection of biomarkers in Staphylococcus aureus from subclinical bovine mastitis.

Methods And Results: A total of 229 S. aureus isolates were obtained from milk samples collected from cows with subclinical mastitis using microbiological culture.

Molecular characterization of persistent subclinical mastitis-causing Staphylococcus aureus from dairy farms.

The study aimed to evaluate the genetic diversity of Staphylococcus aureus causing subclinical mastitis (SM) isolated from dairy cows and to assess the effect of the infection status (transient vs. persistent) on the milk and component yield. A total of six dairy farms in São Paulo state were used for the selection of cows with SM caused by S.

Virulence and antimicrobial resistance genes profiles of spa type t605 methicillin-susceptible Staphylococcus aureus isolated from subclinical bovine mastitis.

Aims: Staphylococcus aureus is one of the most common pathogens associated with mastitis in dairy herds worldwide. This study evaluated the profile of virulence and antimicrobial resistance genes of spa type t605 methicillin-susceptible Staphylococcus aureus isolated from subclinical bovine mastitis in São Paulo, Brazil.

Methods And Results: A total of 57 S.

Antimicrobial activities of polyhexamethylene biguanide against biofilm-producing Prototheca bovis causing bovine mastitis.

Prototheca spp. is a frequent cause of bovine mastitis and is highly resistant to commonly used disinfectants. This study aimed to: (1) evaluate the antimicrobial activity of polyhexamethylene biguanide (PHMB) against mastitis-causing Prototheca spp.

Multiclonal human origin and global expansion of an endemic bacterial pathogen of livestock.

Most new pathogens of humans and animals arise via switching events from distinct host species. However, our understanding of the evolutionary and ecological drivers of successful host adaptation, expansion, and dissemination are limited. is a major bacterial pathogen of humans and a leading cause of mastitis in dairy cows worldwide.

Incidence and Treatments of Bovine Mastitis and Other Diseases on 37 Dairy Farms in Wisconsin.

The aim of this research was to describe the incidence and treatments of mastitis and other common bovine diseases using one year of retrospective observational data (n = 50,329 cow-lactations) obtained from herd management software of 37 large dairy farms in Wisconsin. Incidence rate (IR) was defined as the number of first cases of each disease divided by the number of lactations per farm. Clinical mastitis (CM) remains the most diagnosed disease of dairy cows.

The Impact of Selective Dry Cow Therapy Adopted in a Brazilian Farm on Bacterial Diversity and the Abundance of Quarter Milk.

We aimed to evaluate the impact of selective dry cow therapy (SDCT) (protocol 1: antimicrobial combined with internal teat sealant (ITS); vs. protocol 2: ITS alone) on bacterial diversity and the abundance of quarter milk. Eighty high production cows (parity ≤ 3 and an average milk yield of 36.

Association between antimicrobial use and antimicrobial resistance of Streptococcus uberis causing clinical mastitis.

It is unknown whether overuse of antimicrobials against clinical mastitis (CM) from Streptococcus uberis is associated with increased antimicrobial resistance (AMR). Therefore, the aim of this study was to evaluate the association between antimicrobial use (AMU) and AMR in relation to the Strep. uberis causing CM in dairy herds.

MALDI-TOF MS identification of algae associated with bovine mastitis.

We evaluated the use of MALDI-TOF MS for the identification of 3 major, dairy-associated species, namely, (formerly genotype 2), , and (formerly genotype 1). The MALDI-TOF MS spectra established for those species were introduced into the reference spectra library of the Bruker Biotyper MALDI-TOF MS analysis software. Next, 31 isolates from Holstein cows with mastitis, from herds located in the midwestern area of São Paulo State, Brazil, were subjected to MALDI-TOF MS profiling.

Short communication: Association between the accessory gene regulator (agr) group and the severity of bovine mastitis caused by Staphylococcus aureus.

Staphylococcus aureus can elicit mild to more severe degrees of mastitis in cattle, depending on the response of the host's immune system and the virulence factors of the specific isolate. Several virulence factors are controlled by a global regulatory system, designated accessory gene regulator (agr). Thus, the objective was to examine associations between different capsular and agr types and the severity of bovine mastitis caused by S.

Herd-level associations between somatic cell counts and economic performance indicators in Brazilian dairy herds.

The aims of the present study were to provide a portrait of the techno-economic status of dairy herds in Minas Gerais, Brazil, particularly with respect to bulk-tank somatic cell count (BTSCC) data, and to examine the herd-level associations of BTSCC with various economic performance indicators (EPI). Data from 543 herds, 1,052 herd-year records in total, spread over 3 years (2015-2017), from the South and Southwest mesoregions of Minas Gerais State were provided by the Brazilian Support Agency to Micro and Small Companies Division Minas Gerais (SEBRAE). Herds had an average of 82 lactating cows per herd, milk yield of 17 L/cow per day, and availability of financial information via routine monthly economic surveys.

First investigation of Staphylococcus argenteus in a Brazilian collections of S. aureus isolated from bovine mastitis.

Background: Staphylococcus argenteus is a new specie positive coagulase staphylococci. We investigate the presence of S. argenteus in isolates previously classified as S.

Chronic subclinical mastitis reduces milk and components yield at the cow level.

We evaluated the effects of chronic subclinical mastitis (CSM) caused by different types of pathogens on milk yield and milk components at the cow level. A total of 388 Holstein cows had milk yield measured and were milk sampled three times at intervals of two weeks for determination of SCC and milk composition, and microbiological culture was performed. Cows were considered healthy if all three samples of SCC were ≤200 000 cells/ml and were culture-negative at the third milk sampling.

Association of herd-level risk factors and incidence rate of clinical mastitis in 20 Brazilian dairy herds.

The objectives of this study were to characterize the pathogen frequency and severity of clinical mastitis (CM) in 20 dairy herds of southeastern Brazil; and to determine the incidence rate of clinical mastitis (IRCM; overall and based on specific-pathogen groups) based on quarter time at risk and its association with risk factors at the herd-level. Data were recorded in each herd for a period of 8 to 15 months. The association between herd-level risk factors and IRCM were determined by two groups of mixed regression models: one based on the overall IRCM, and five based on the following specific-pathogen groups: contagious, other Gram-positive, Gram-negative, other, and negative culture.

Direct identification of bovine mastitis pathogens by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in pre-incubated milk.

The present study aimed to compare two MALDI-TOF identification methods [(a) direct sample identification after pre-incubation; or (b) use of bacteria isolated on pre-culture)] to standard, traditional bench microbiology. A total of 120 quarter milk samples from 40 Holstein lactating cows were screened based on culture-positive results obtained by microbiological culture (reference method) with the following numbers of quarters positive per cow: 4 cows with 1, 8 cows with 2, 12 cows with 3 and 16 cows with 4 infected quarters per cow. For direct identification method, quarter milk samples (n=120) were skimmed by centrifugation (10,000×g/10min) and pre-incubated at 37°C for 12h.

Milk losses associated with somatic cell counts by parity and stage of lactation.

The reduction of milk production caused by subclinical mastitis in dairy cows was evaluated through the regression of test-day milk yield on log-transformed somatic cell counts (LnSCC). Official test-day records (n = 1,688,054) of Holstein cows (n = 87,695) were obtained from 719 herds from January 2010 to December 2015. Editing was performed to ensure both reliability and consistency for the statistical analysis, and the final data set comprised 232,937 test-day records from 31,692 Holstein cows in 243 herds.

Using milk leukocyte differentials for diagnosis of subclinical bovine mastitis.

This research study aimed to evaluate the use of the milk leukocyte differential (MLD) to: (a) identify quarter milks that are culture-positive; and (b) characterize the milk leukocyte responses to specific groups of pathogens causing subclinical mastitis. The MLD measures the absolute number and relative percentage of inflammatory cells in milk samples. Using the MLD in two dairy herds (170 and 172 lactating cows, respectively), we studied all lactating cows with a most recent monthly Dairy Herd Improvement Association somatic cell count (SCC) >200 × 103 cells/ml.

Non-culture-based identification of mastitis-causing bacteria by MALDI-TOF mass spectrometry.

The purpose of this study was to evaluate the detection limit of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for direct identification, without previous microbiological culture, of bovine mastitis-causing bacteria from milk samples. Milk samples (n = 15) were experimentally contaminated with Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae, Streptococcus dysgalactiae, and Escherichia coli to have bacterial counts ranging from 10 to 10 cfu/mL. These contaminated milk samples were subjected to a preparation protocol for bacterial ribosomal protein extraction using the MALDI Sepsityper kit (Bruker Daltonik, Bremen, Germany), which allowed MALDI-TOF MS coupled with Biotyper software (Bruker Daltonik) to identify bacterial fingerprints based on intact ribosomal proteins.