Coagulase-negative and Coagulase-positive staphylococcus difference

                                                                                 Keerthi vasan R.

What is Coagulase:

Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates. Importantly,S. aureus is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of S. aureus or any of the other 11 coagulase-positive Staphylococci. A negative coagulase test would instead show the presence of coagulase-negative organisms such as S. epidermidis or S. saprophyticus. However, it is now known that not all S. aureus are coagulase-positive.Whereas coagulase-positive Staphylococci are usually pathogenic, coagulase-negative Staphylococci are more often associated with opportunistic infection.

 

Coagulase reacts with prothrombin in the blood. The resulting complex is called staphylothrombin, which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood. Coagulase is tightly bound to the surface of the bacterium S. aureus and can coat its surface with fibrin upon contact with blood. The fibrin clot may protect the bacterium from phagocytosis and isolate it from other defenses of the host.The fibrin coat can therefore make the bacteria more virulent. Bound coagulase is part of the larger family of MSCRAMM adhesin proteins.

 

Coagulase Test:

Coagulase is an enzyme that works in conjugation with normal plasma components to convert fibrinogen to finbrin and causes clotting of plasma. This enzyme is a good indicator of pathogenic potential of Staphylococcus aureus. As 97% of the strains of S. aureus have proven to be coagulase positive, the Coagulse test is useful for differentiating S. aureus from other Gram positive, Catalase positive cocci.

Positive coagulase test is shown by:Staphylococcus aureus, S. pseudintermedius, S. intermedius, S. schleiferi, S. delphini, S. hyicus, S. lutrae etc.

Negative coagulase test is shown by:Staphylococcus epidermidis, S. saprophyticus, S. warneri, S. hominis, S. caprae etc.

 

 

Coagulase-negative VS Coagulase-positive staphylococcus difference:

	Coagulase-positive staphylococcus	Coagulase-negative staphylococcus
Gram Staining	Gram-positive	Gram-positive
Shape	coccus	Coccus occurring in clusters.
Respiration	facultative aeroanaerobic	aerobic
Motility	non motile	non motile
Endospores	Non spore-forming	Non spore-forming
Infection	opportunistic infection	opportunistic infection and zoonotic infection
Examples	Staphylococcus aureus, S. pseudintermedius, S. intermedius, S. schleiferi, S. delphini, S. hyicus, S. lutrae etc.	Staphylococcus epidermidis, S. saprophyticus, S. warneri, S. hominis, S. caprae etc.

 

 

 

 

Human Infection:

Coagulase-positive staphylococcus	Coagulase-negative staphylococcus
found on the skin and mucous membranes & also been isolated in the natural environment	Part of normal human skin flora
Found on the skin, nose and throat in warm-blood animals	Infections of the bloodstream and other tissue sites.
collection of pus, such as a boil or furuncle, or abscess. The area is typically tender or painful and may be reddened or swollen	abdominal pain and tenderness, fever, nausea, and vomiting

 

Lab Diagnosis:

	Coagulase-positive staphylococcus	Coagulase-negative staphylococcus
Specimen	Blood, urine, skin, infected material or nasal secretions	Blood, urine, skin, infected material or nasal secretions

 

Diagnosis:

Diagnosis is based on performing tests with colonies. Tests for clumping factor, coagulase, hemolysins and thermostable deoxyribonuclease are routinely used to identify S aureus. Commercial latex agglutination tests are available. Identification of S epidermidis is confirmed by commercial biotyping kits.

Treatment:

	Coagulase-positive staphylococcus	Coagulase-negative staphylococcus
Antibiotic	Vancomycin,Oxacillin,penicillin,methicillin(oxacillin,nafcillin)	cefazolin, nafcillin, oxacillin, vancomycin, daptomycin and linezolid

 

Prevention Coagulase-negative and Coagulase-positive staphylococcus:

 

1. Wash your hands: Thorough hand washing is your best defense against germs. Wash your hands with soap and water briskly for at least 20 seconds. Then dry them with a disposable towel and use the towel to turn off the faucet. If your hands aren't visibly dirty or you aren't able to wash your hands, you can use an alcohol-based hand sanitizer.Wash your hands with soap and water regularly, such as before, during and after making food; after handling raw meat or poultry; before eating; after using the bathroom; and after touching an animal or animal waste.

 

2. Keep wounds covered: Keep cuts and scrapes clean and covered with sterile, dry bandages until they heal. The pus from infected sores often contains staph bacteria. Keeping wounds covered will help keep the bacteria from spreading.

3. Reduce tampon risks: Toxic shock syndrome is caused by staph bacteria. Tampons left in for long periods can grow staph bacteria. You can reduce your chances of getting toxic shock syndrome by changing your tampon frequently — at least every 4 to 8 hours. Use the lowest absorbency tampon you can. Try to alternate tampons with sanitary napkins whenever possible.

4. Keep personal items personal: Avoid sharing personal items such as towels, sheets, razors, clothing and athletic equipment. Staph infections can spread on objects, as well as from person to person.

5. Wash clothing and bedding: Staph bacteria can spread on clothing, towels and bedding. To remove bacteria, wash and dry items at the warmest temperature recommended by the items' labels. It's OK if you can't use hot water, as using detergent in your wash is enough to make items clean and safe for use. You can use bleach on any bleach-safe materials.

6. Take food safety precautions:Wash your hands before handling food. If food will be out for a while, make sure that hot foods stay hot — above 140 F (60 C). Make sure that cold foods stay at 40 F (4.4 C) or below. Refrigerate leftovers as soon as possible. Wash cutting boards and counters with soap and water.