scholarly journals Prevalence, antibiotic resistance, virulence and genetic diversity of Staphylococcus aureus isolated from bulk tank milk samples of U.S. dairy herds

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Kruthika Patel ◽  
Sandra M. Godden ◽  
Erin E. Royster ◽  
Brian A. Crooker ◽  
Timothy J. Johnson ◽  
...  
Keyword(s):  
Public Health ◽  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Dairy Cows ◽  
Virulence Genes ◽  
Dairy Herds ◽  
Drug Resistant ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Bulk Tank

Abstract Background Colonization of dairy cows by Staphylococcus aureus (S. aureus), especially those which are multi-drug resistant and toxin producing, is a concern for animal health and well-being as well as public health. The objective of this study was to investigate the prevalence, antibiotic resistance, gene content and virulence determinants of S. aureus in bulk tank milk samples (BTM) from U.S. dairy herds. Results BTM samples were collected, once in winter and once in summer, from 189 U.S. dairy herds. Of 365 BTM samples cultured, the sample and herd prevalence of S. aureus in BTM was 46.6% (170 of 365 samples) and 62.4% (118 of 189 herds), respectively. Among a subset of 138 S. aureus isolates that were stored for further analysis, 124 were genome sequenced after being confirmed as S. aureus using phenotypic tests. The most commonly identified antimicrobial resistance-associated gene was norA (99.2%) and mecA gene responsible for methicillin resistance (MRSA) was identified in one isolate (0.8%). The most frequently detected putative virulence genes were aur (100%), hlgB (100%), hlgA, hlgC, hlb (99.2%), lukE (95.9%) and lukD (94.3%). In the 53 staphylococcal enterotoxin positive isolates, sen (37.9%), sem (35.5%), sei (35.5%) and seg (33.1%) were the most frequently detected enterotoxin genes. Among the 14 sequence types (ST) and 18 spa types identified, the most common was ST2187 (20.9%) and t529 (28.2%), respectively. The most predominant clone was CC97 (47.6%) followed by CC unknown (36.3%). The single MRSA isolate belonged to ST72-CC8, spa type t126 and was negative for the tst gene but harbored all the other virulence genes investigated. Conclusion Our findings indicated a high prevalence of S. aureus in BTM of U.S. dairy herds, with isolates showing little evidence of resistance to antibiotics commonly used to treat mastitis. However, isolates often carried genes for the various enterotoxins. This study identified predominant genetic clones. Despite lower prevalence, the presence of MRSA and multi-drug resistant strains in BTM poses a significant risk to animal and public health if their number were to increase in dairy environment. Therefore, it is necessary to continuously monitor the use of antibiotics in dairy cows.

Comparison of Antimicrobial Susceptibility of Staphylococcus aureus Isolated from Bulk Tank Milk in Organic and Conventional Dairy Herds in the Midwestern United States and Denmark

2004 ◽  
Vol 67 (6) ◽  
pp. 1104-1110 ◽  
Author(s):  
K. SATO ◽  
T. W. BENNEDSGAARD ◽  
P. C. BARTLETT ◽  
R. J. ERSKINE ◽  
J. B. KANEENE
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Dairy Farms ◽  
Dairy Herds ◽  
Bulk Tank Milk ◽  
Aureus Isolate ◽  
Milk Samples ◽  
Bulk Tank

An observational study was conducted to compare the antimicrobial susceptibility patterns of Staphylococcus aureus isolated from bulk tank milk in organic and conventional dairy farms in Wisconsin, United States, and southern Jutland, Denmark. Bulk tank milk samples and data regarding management and production were collected from 30 organic and 30 conventional dairy farms in Wisconsin and 20 organic and 20 conventional dairy farms in Denmark. S. aureus isolates were tested for resistance against 15 antimicrobial agents by semiautomatic microbroth dilution methods in each country. Of the 118 bulk tank milk samples in Wisconsin, 71 samples (60%) yielded at least one S. aureus isolate, and a total of 331 isolates were collected. Of the 40 bulk tank milk samples from Denmark, 27 samples (55%) yielded at least one S. aureus isolate, and a total of 152 isolates were collected. Significant differences between organic and conventional dairies were detected only to ciprofloxacin in Wisconsin and avilamycin in Denmark. Significant differences (P < 0.05) between the two countries were detected in nine antimicrobials. Denmark had a higher probability of having reduced susceptibility to ciprofloxacin and streptomycin (P = 0.015 and 0.003, respectively). Wisconsin isolates had a higher probability of having reduced susceptibility to seven other antimicrobial agents (bacitracin, gentamicin, kanamycin, penicillin, sulphamethoxazole, tetracycline, and trimethoprim). We found small differences between organic and conventional farm types in each country and larger differences between the two national agricultural systems.

scholarly journals Determination of the occurrence of plasmid virulence genes (spv) and antibiotic resistance of Salmonella strains isolated from raw milk

2018 ◽  
Vol 74 (1) ◽  
pp. 59-64 ◽  
Author(s):  
AGNIESZKA WISZNIEWSKA-ŁASZCZYCH ◽  
BARBARA ZDRODOWSKA ◽  
BEATA WYSOK ◽  
JOANNA SZTEYN ◽  
KATARZYNA LIEDTKE ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Virulence Genes ◽  
Raw Milk ◽  
Molecular Methods ◽  
Frequency Of Occurrence ◽  
Salmonella Spp ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Bulk Tank

The aim of the study was to measure the frequency of occurrence of Salmonella spp. in raw milk, to identify their serotype, as well as to determine their antibiotic resistance and the presence of Salmonella plasmid virulence (spv) genes. Out of 300 bulk tank milk samples, 5.3% were contaminated with Salmonella spp. All strains isolated belonged to the serovar S enteritidis, as confirmed by serotyping and molecular methods. The presence of spv genes was determined by PCR. Spv genes were present, in different patterns, in all strains tested. SpvA gene was present in all isolates (100%), spvB in 56.25%, spvC in 62.5%, spvD in 75%, and spvR in 56.25%. Antibiotic resistance was evaluated according to the NCCLS recommendations. All isolates were sensitive to ciprofloxacin (CIP), gentamicin (GE), and chloramphenicol (CH). Thirteen strains were resistant to ampicillin (AMP), 8 to erythromycin (E), 1 to doxycycline (DO), and 1 to tetracycline (TE). Different frequency of occurrence of the spv genes in Salmonella strains isolated from raw milk demonstrates their high adaptability. As many as 87.5% of isolates showed resistance to at least one of the antibiotics tested....

scholarly journals Prevalence of methicillin-resistant Staphylococcus aureus and pattern of antimicrobial resistance in mastitis milk of cattle in Chitwan, Nepal

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Asmita Shrestha ◽  
Rebanta Kumar Bhattarai ◽  
Himal Luitel ◽  
Surendra Karki ◽  
Hom Bahadur Basnet
Keyword(s):  
Public Health ◽  
Staphylococcus Aureus ◽  
Antimicrobial Resistance ◽  
Subclinical Mastitis ◽  
World Health ◽  
Dairy Herds ◽  
Microbiological Analysis ◽  
Biochemical Tests ◽  
Methicillin Resistant ◽  
Milk Samples

Abstract Background The threat of methicillin-resistant Staphylococcus aureus (MRSA) exists globally and has been listed as a priority pathogen by the World Health Organization. One of the sources of MRSA emergence is livestock and its products, often raised in poor husbandry conditions. There are limited studies in Nepal to understand the prevalence of MRSA in dairy animals and its antimicrobial resistance (AMR) profile. A cross-sectional study was conducted in Chitwan, one of the major milk-producing districts of Nepal, from February 2018 to September 2019 to estimate the prevalence of MRSA in milk samples and its AMR profile. The collected milk samples (n = 460) were screened using the California Mastitis Test (CMT) and positive samples were subjected to microbiological analysis to isolate and identify S. aureus. Polymerase Chain Reaction (PCR) was used to identify the presence of the mecA gene and screen for MRSA. Results In total, 41.5% (191/460) of milk samples were positive in the CMT test. Out of 191 CMT positive milk samples, the biochemical tests showed that the prevalence of S. aureus was 15.2% (29/191). Among the 29 S. aureus isolates, 6.9% (2/29) were identified as MRSA based on the detection of a mecA gene. This indicates that that 1.05% (2/191) of mastitis milk samples had MRSA. The antibiotic sensitivity test showed that 75.9% (22/29) and 48.3% (14/29) S. aureus isolates were found to be sensitive to Cefazolin and Tetracycline respectively (48.3%), whereas 100% of the isolates were resistant to Ampicillin. In total 96.6% (28/29) of S. aureus isolates were multidrug-resistant (MDR). Conclusions This study revealed a high prevalence of S. aureus-mediated subclinical mastitis in dairy herds in Chitwan, Nepal, with a small proportion of it being MRSA carrying a mecA gene. This S. aureus, CoNS, and MRSA contaminated milk poses a public health risk due to the presence of a phenotype that is resistant to very commonly used antibiotics. It is suggested that dairy herds be screened for subclinical mastitis and treatments for the animals be based on antibiotic susceptibility tests to reduce the prevalence of AMR. Furthermore, future studies should focus on the Staphylococcus spp. to explore the antibiotic resistance genes in addition to the mecA gene to ensure public health.

scholarly journals Rapid Detection of Mycoplasma bovis, Staphylococcus aureus and Streptococcus agalactiae in Cattle Bulk Tank Milk in Cyprus and Relations with Somatic Cell Counts

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 841
Author(s):  
Maria Liapi ◽  
George Botsaris ◽  
Costas Arsenoglou ◽  
Nikolas Markantonis ◽  
Christodoulos Michael ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Somatic Cell ◽  
Real Time ◽  
Streptococcus Agalactiae ◽  
Mycoplasma Bovis ◽  
Bulk Tank Milk ◽  
Somatic Cell Counts ◽  
Milk Samples ◽  
Cell Counts ◽  
Bulk Tank

One hundred and seventy-seven (177) bulk tank milk samples were analyzed with a commercially available real-time polymerase chain reaction kit and 11 (6.21%), 41 (23.16%), and 58 (32.77%) tested positive for Mycoplasma bovis, Staphylococcus aureus, and Streptococcus agalactiae, respectively. Statistical analysis revealed a significant relationship between the presence of S. aureus and S. agalactiae. Enumeration of somatic cells was performed in the same samples by flow cytometry. The somatic cell counts were found higher in S. aureus and S. agalactiae positive samples. No association was found between M. bovis presence and somatic cells counts. Low internal assay control Ct values were found to be related with high somatic cell counts. Noticeably, this is the first report for the presence of M. bovis in Cyprus. Therefore, its presence was confirmed by bulk tank milk culture, conventional PCR, and next generation sequencing. Furthermore, M. bovis was typed with multilocus sequencing typing and was allocated to sequence type 29 (ST 29). Real-time PCR in bulk tank milk samples is a useful tool to detect mammary infections, especially for neglected pathogens such as M. bovis.

scholarly journals Molecular characterization of virulence factors in Staphylococcus aureus isolated from bovine subclinical mastitis in central Ethiopia

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Desiye Tesfaye Tegegne ◽  
Gezahegne Mamo ◽  
Hika Waktole ◽  
Yohannes Equar Messele
Keyword(s):  
Staphylococcus Aureus ◽  
Dairy Cows ◽  
Virulence Factors ◽  
Virulence Genes ◽  
Animal Health ◽  
Subclinical Mastitis ◽  
Biochemical Tests ◽  
Milk Samples ◽  
Lactating Dairy Cows ◽  
Genomic Study

Abstract Purpose Staphylococcus aureus (S. aureus) is the most important pathogen involved in bovine mastitis in dairy production. S. aureus produces a spectrum of extracellular protein toxins and virulence factors which are thought to contribute to the pathogenicity of the organism. The aim of this work was to isolate and molecular characterize S. aureus associated with bovine subclinical mastitis in the central part of Ethiopia. Methods A total of 265 lactating dairy cows from various dairy farms in four different geographical locations were screened by the California mastitis test (CMT) for bovine subclinical mastitis. One hundred thirty CMT-positive milk samples were collected and transported to the laboratory. Different biochemical tests and polymerase chain reaction (PCR) were used for the identification of S. aureus isolates. Finally, PCR was performed for molecular detection of virulence genes. Results From a total of 265 lactating dairy cows screened, 49% (n = 130) were positive for bovine subclinical mastitis. One hundred thirty mastitic milk samples were subjected to bacterial culturing, and one hundred (76%) S. aureus isolates were identified based on phenotypic characters. Sixty-eight confirmed S. aureus isolates were obtained using PCR. The confirmed S. aureus isolates were tested for six virulence genes (tsst-1, hlb, eta, sea, clfA, and icaD) using PCR. Of the six virulence genes screened from all the isolates, only two (clfA and eta) were detected in the isolates. Out of 68 isolates, 25% and 22% were possessed the eta and clfA genes, respectively. Conclusion The presence of Staphylococcus aureus having virulence genes (eta and clfA) revealed that mastitis is a major concern nowadays affecting animal health, milk quality, and yield. Further genomic study of these isolates will provide broad new insights on virulence.

scholarly journals Mycoplasmal mastitis in dairy cows in the Moghan region of Ardabil State, Iran : short communication

2006 ◽  
Vol 77 (4) ◽  
Author(s):  
C. Ghazaei
Keyword(s):  
Dairy Cows ◽  
Short Communication ◽  
Bovine Mastitis ◽  
Subclinical Mastitis ◽  
Clinical Mastitis ◽  
Mycoplasma Bovis ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
The World ◽  
Bulk Tank

Mycoplasmas are an important and economically significant cause of mastitis in dairy cows in various parts of the world. The organisms are highly contagious, with the main reservoir of infection originating from cows with subclinical mastitis. In 1998 the 1st cases of bovine mastitis due to Mycoplasma bovis were diagnosed in Ardabil State, Iran. An investigation was carried out with the aim of establishing the extent of mycoplasma infections in dairy cows in Ardabil State. Milk samples obtained from 80 cows with clinical mastitis were cultured in the laboratory for the presence of mycoplasmas. Similarly, 48 bulk-tank milk samples were examined for the presence of mycoplasmas. A modified Hayflick broth was used to isolate the mycoplasmas and an immunoperoxidase test used for the species identification of the isolates. Mycoplasma bovis was isolated from 39 (48.75 %) of the clinical mastitis samples and from 48 of the bulk-tank milk samples tested. This indicated that mycoplasma udder infections were more prevalent in dairy cows in Ardabil State than previously thought.

scholarly journals Surveillance of Antibiotic Resistance of Maltose-Negative Staphylococcus aureus in South African Dairy Herds

Antibiotics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 616
Author(s):  
Joanne Karzis ◽  
Inge-Marié Petzer ◽  
Edward F. Donkin ◽  
Vinny Naidoo ◽  
Eric M.C. Etter
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
South African ◽  
Inhibitory Concentration ◽  
Aureus Strain ◽  
Diffusion Method ◽  
Dairy Herds ◽  
Disk Diffusion Method ◽  
Data Set ◽  
Milk Samples

Antibiotic resistance has been reported since the 1940s in both human and veterinary medicine. Many years of monitoring milk samples in South Africa led to identification of a novel maltose-negative Staphylococcus aureus (S. aureus) strain, which appears to be an emerging pathogen. In this study, the susceptibility of this strain to antibiotics was evaluated over time, during diverse seasons in various provinces and according to somatic cell count (SCC) categories. A data set of 271 maltose-negative S. aureus isolates, from milk samples of 117 dairy herds, was examined using the disk diffusion method, between 2010 and 2017. This study also compared the susceptibility testing of 57 maltose-negative and 57 maltose-positive S. aureus isolated from 38 farms, from three provinces using minimum inhibitory concentration (MIC). The MIC results for the maltose-negative S. aureus isolates showed highest resistance to ampicillin (100%) and penicillin (47.4) and lowest resistance (1.8%) to azithromycin, ciprofloxacin and erythromycin. The maltose-negative S. aureus isolates showed overall significantly increased antibiotic resistance compared to the maltose-positive strains, as well as multidrug resistance. Producers and veterinarians should consider probability of cure of such organisms (seemingly non-chronic) when adapting management and treatment, preventing unnecessary culling.

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