Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci
<i>Staphylococcus aureus</i> is one of the most concerning mastitis-causing pathogens in dairy cattle. Using basic microbiological techniques, <i>S. aureus</i> is typically identified by colony characteristics and hemolysis on blood agar where isolates without hemolysis are t...
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MDPI AG
2021-01-01
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| Online Access: | https://www.mdpi.com/2076-2615/11/2/252 |
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| author | Valerie E. Ryman Felicia M. Kautz Steve C. Nickerson |
| author_facet | Valerie E. Ryman Felicia M. Kautz Steve C. Nickerson |
| author_sort | Valerie E. Ryman |
| collection | DOAJ |
| description | <i>Staphylococcus aureus</i> is one of the most concerning mastitis-causing pathogens in dairy cattle. Using basic microbiological techniques, <i>S. aureus</i> 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 <i>S. aureus</i> 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 <i>S. aureus</i> 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 <i>S. aureus</i>. A selection of isolates was tested using API<sup>®</sup> Staph to biochemically confirm <i>S. aureus</i> identification. Data showed that 63.96% of isolates presumed to be CNS isolates were identified as <i>S. aureus</i>, 9.46% of isolates presumed to be CNS isolates were identified as coagulase-positive staphylococci (CPS) species (but not <i>S. aureus</i>), and 26.58% of samples that were presumed to be CNS isolates were identified correctly. |
| first_indexed | 2024-03-09T04:10:07Z |
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| id | doaj.art-e10b181abfc7436d96d98d65b300b26a |
| institution | Directory Open Access Journal |
| issn | 2076-2615 |
| language | English |
| last_indexed | 2024-03-09T04:10:07Z |
| publishDate | 2021-01-01 |
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| record_format | Article |
| series | Animals |
| spelling | doaj.art-e10b181abfc7436d96d98d65b300b26a2023-12-03T14:01:29ZengMDPI AGAnimals2076-26152021-01-0111225210.3390/ani11020252Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative StaphylococciValerie E. Ryman0Felicia M. Kautz1Steve C. Nickerson2Department of Animal and Dairy Science, University of Georgia, Athens, GA 30605, USADepartment of Animal and Dairy Science, University of Georgia, Athens, GA 30605, USADepartment of Animal and Dairy Science, University of Georgia, Athens, GA 30605, USA<i>Staphylococcus aureus</i> is one of the most concerning mastitis-causing pathogens in dairy cattle. Using basic microbiological techniques, <i>S. aureus</i> 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 <i>S. aureus</i> 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 <i>S. aureus</i> 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 <i>S. aureus</i>. A selection of isolates was tested using API<sup>®</sup> Staph to biochemically confirm <i>S. aureus</i> identification. Data showed that 63.96% of isolates presumed to be CNS isolates were identified as <i>S. aureus</i>, 9.46% of isolates presumed to be CNS isolates were identified as coagulase-positive staphylococci (CPS) species (but not <i>S. aureus</i>), and 26.58% of samples that were presumed to be CNS isolates were identified correctly.https://www.mdpi.com/2076-2615/11/2/252misdiagnosis<i>Staphylococcus aureus</i>CNSNAShemolysis |
| spellingShingle | Valerie E. Ryman Felicia M. Kautz Steve C. Nickerson Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci Animals misdiagnosis <i>Staphylococcus aureus</i> CNS NAS hemolysis |
| title | Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci |
| title_full | Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci |
| title_fullStr | Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci |
| title_full_unstemmed | Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci |
| title_short | Case Study: Misdiagnosis of Nonhemolytic <i>Staphylococcus aureus</i> Isolates from Cases of Bovine Mastitis as Coagulase-Negative Staphylococci |
| title_sort | case study misdiagnosis of nonhemolytic i staphylococcus aureus i isolates from cases of bovine mastitis as coagulase negative staphylococci |
| topic | misdiagnosis <i>Staphylococcus aureus</i> CNS NAS hemolysis |
| url | https://www.mdpi.com/2076-2615/11/2/252 |
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