Effects of Autogenous Toxoid-bacterin in Lactating Cows with Staphylococcus aureus Subclinical Mastitis.

Bovine mastitis is a major disease affecting dairy cattle, and Staphylococcus aureus is one of the most important agent involved in this condition due to its capacity to produce enterotoxins and develop resistance to antimicrobial agents. This study aimed to detect S. aureus strains in milk samples from cows with subclinical mastitis employing microbiological and molecular analysis. Eleven farms were visited and from 187 lactating cows sampled, 33 S. aureus strains were isolated. Only one of the 33 strains was positive for mecA resistance gene, 23 were positive for sea enterotoxin gene, and none was positive for seb or sec enterotoxin gene. S. aureus strains were submitted to in vitro antimicrobial susceptibility test and 63.6% (21/33) were susceptible to all antimicrobials tested, while 36.3% (12/33) were resistant to one or more antimicrobial agents. Identification of mecA and the sea genes highlighted the need to elaborate strategies to reduce problems related to animal. Furthermore, the identification of bovine mastitis caused by S. aureus is very important to manage herd and to public health, since milk contaminated by this pathogen can lead to serious health problems.

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PHENOTYPIC STUDY ON THE CAPACITY OF BIOFILM PRODUCTION IN STAPHYLOCOCCUS AUREUS ISOLATED FROM BOVINE SUBCLINICAL MASTITIS AND THEIR IMPACT ON RESISTANCE TO ANTIMICROBIALS

Basrah Journal of veterinary Research ◽

10.33762/bvetr.2016.124293 ◽

2016 ◽

Vol 15 (2) ◽

pp. 111-127

Author(s):

Ali A. Al-Iedani

Keyword(s):

Staphylococcus Aureus ◽

Subclinical Mastitis ◽

Biofilm Production

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

BMC Veterinary Research ◽

10.1186/s12917-021-02942-6 ◽

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.

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Interpretation of California mastitis test scores using Staphylococcus aureus culture results for screening of subclinical mastitis in low yielding smallholder dairy cows in the Dar es Salaam region of Tanzania

Preventive Veterinary Medicine ◽

10.1016/j.prevetmed.2006.10.011 ◽

2007 ◽

Vol 78 (3-4) ◽

pp. 274-285 ◽

Cited By ~ 12

Author(s):

F.M. Kivaria ◽

J.P.T.M. Noordhuizen ◽

M. Nielen

Keyword(s):

Staphylococcus Aureus ◽

Dairy Cows ◽

Test Scores ◽

Subclinical Mastitis ◽

Dar Es Salaam ◽

California Mastitis Test ◽

Smallholder Dairy

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Case Study: Misdiagnosis of Nonhemolytic Staphylococcus aureus Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci

Animals ◽

10.3390/ani11020252 ◽

2021 ◽

Vol 11 (2) ◽

pp. 252

Author(s):

Valerie E. Ryman ◽

Felicia M. Kautz ◽

Steve C. Nickerson

Keyword(s):

Staphylococcus Aureus ◽

Bovine Mastitis ◽

Dairy Farm ◽

Blood Agar ◽

Coagulase Negative Staphylococci ◽

Mannitol Salt Agar ◽

Lactating Cows ◽

Presumptive Identification ◽

Microbiological Techniques

Staphylococcus aureus is one of the most concerning mastitis-causing pathogens in dairy cattle. Using basic microbiological techniques, S. aureus is typically identified by colony characteristics and hemolysis on blood agar where isolates without hemolysis are typically considered to be coagulase-negative staphylococci (CNS) isolates. Herein, we present a decade-long case study where suspected S. aureus isolates from one Georgia dairy farm were further tested to confirm presumptive identification. Presumptive identification of bacterial growth from 222 mammary secretions from bred Holstein heifers and lactating cows was conducted at the time of collection. Presumptive identification of S. aureus on blood agar was based on observation of colony morphology, color, and presence or absence of a broad zone of incomplete hemolysis and a smaller zone of complete hemolysis at 48 h. Those without hemolysis were presumptively characterized as CNS. All isolates were further plated on mannitol salt agar and a coagulase test was performed. A positive for both of these tests together was deemed to be S. aureus. A selection of isolates was tested using API® Staph to biochemically confirm S. aureus identification. Data showed that 63.96% of isolates presumed to be CNS isolates were identified as S. aureus, 9.46% of isolates presumed to be CNS isolates were identified as coagulase-positive staphylococci (CPS) species (but not S. aureus), and 26.58% of samples that were presumed to be CNS isolates were identified correctly.

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

Annals of Microbiology ◽

10.1186/s13213-021-01639-3 ◽

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.

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