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15 Cards in this Set
- Front
- Back
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white/yellowish colonies
cocci in clusters beta gamma hemolysis catalase positive coagulase positive optochin resistant |
Staph aureus
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White colonies
cocci in clusters gamma hemolysis catalase positive coagulase negative optochin resistant PYR usually negative novobicin sensitive |
Staphlococcus epidermidis
coagulase negative staph S. epidermidis is also a major concern for people with catheters or other surgical implants because it is known to cause biofilms that grow on these devices. |
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grey colonies
cocci in chains gamma, alpha hemolysis catalse negative coagulase negative optochin resistant PYR + Novobicin sensitive |
Enterococcus faecium
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What is the purpose of the PYR stain?
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Organisms possessing the enzyme L-pyrrolidonyl arylamidase can hydrolyze the disk substrate L-pyrrolidonyl-�-naphthylamide to release L-pyrrolidone and �-naphthylamide. Visual detection can be achieved by the addition of PYR/LAP Reagent .the active ingredient, p-dimethylaminocinnamaldehyde, combines with the end-product �-naphthylamide to form a red Schiff base. A positive reaction is a yellow to red color change.
PYR disks are mainly used for the presumptive identification of group A �-hemolytic streptococci (i.e. Streptococcus pyogenes). Among the commonly encountered b-hemolytic streptococci only S. pyogenes produces a positive reaction. The accuracy and rapidity of the PYR test allows for quicker reporting of results for those cultures screened for group A streptococci and can result in better patient care and treatment. PYR disks can also be used for the presumptive identification of Enterococcus species. The most accurate presumptive identification of a catalase-negative gram-positive coccus as an Enterococcus strain is by demonstrating that the unknown strain is PYR and LAP positive and grows in 6.5% NaCl, and at 45�C. |
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grey colonies
cocci in chains alpha hemolysis catalase positive coagulase positive optochin resistant pyr negative novobicin sensitive |
Streptococcus viridans
Viridans streptococci can be differentiated from Streptococcus pneumoniae using an optochin test, as Viridans streptococci are optochin resistant; they also lack either the polysaccharide-based capsule typical of S. pneumoniae |
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clear to grey colonies
cocci in chains large zone of beta hemolysis catalase negative coagulase negative optochin resistant PYR + Novobicin sensitive |
Strep pyogenes (Group A)
Throat cultures |
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clear to grey colonies
cocci in chains small zone of beta hemolysis catalase negative coagulase negative optochin resistant PYR - Novobicin sensitive |
Step agalacticiae
S. agalactiae is a species of the normal flora of the female urogenital tract and rectum. Its chief clinical importance is that it can be transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection. In the western world, S. agalactiae is the major cause of bacterial septicemia of the newborn, which can lead to death or long-term sequelae. S. agalactiae can also cause neonatal meningitis, which does not present with the hallmark sign of adult meningitis, a stiff neck; rather, it presents with nonspecific symptoms such as fever, vomiting and irritability and can consequently go undiagnosed until it is too late. |
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clear, mucoid colonies
diplococci in short chains alpha hemolysis coagulase negative catalase negative optochin SENSITIVE PYR - Novobicin sensitive Only optochin sensitive organism that we studied in lab |
Strep pneumoniae
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white colonies
cocci in clusters gamma hemolysis catalase positive coagulase negative optochin resistant PYR - novobicin resistant |
Staph saprophyticus
m Wikipedia, the free encyclopedia Jump to: navigation, search Staphylococcus saprophyticus Scientific classification Kingdom: Bacteria Phylum: Firmicutes Class: Cocci Order: Bacillales Family: Staphylococcaceae Genus: Staphylococcus Species: S. saprophyticus Binomial name Staphylococcus saprophyticus Staphylococcus saprophyticus is a coagulase-negative species of Staphylococcus bacteria. S. saprophyticus is often implicated in urinary tract infections. S. saprophyticus is resistant to the antibiotic Novobiocin, a characteristic that is used in laboratory identification to distinguish it from S. epidermidis, which is also coagulase- negative. |
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What is alpha hemolysis?
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When Alpha hemolysis (α-hemolysis) is present the agar under the colonies is dark and greenish. Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha hemolysis. This is sometimes called green hemolysis because of the color change in the agar. Other synonymous terms are incomplete hemolysis and partial hemolysis. Alpha hemolysis is caused by hydrogen peroxide produced by the bacterium, oxidizing hemoglobin to green methemoglobin.
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What is beta hemolysis?
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eta hemolysis (β-hemolysis), sometimes called complete hemolysis, is a complete lysis of red cells in the media around and under the colonies: the area appears lightened and transparent. Streptococcus pyogenes, or Group A beta-hemolytic Strep (GAS), displays beta hemolysis.
Some weakly beta-hemolytic species cause intense beta hemolysis when grown together with a strain of Staphylococcus. This is called the CAMP test1. Streptococcus agalactiae displays this property. Clostridium perfringens can be identified presumptively with this test. |
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Gram positive anaerobes
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Cocci: peptostreptococci
Bacilli: Clostridium, Actinomyces, Propionibacterium |
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Gram positive aerobes
Bacilli |
Branching: Nocardia
Non-Branching: Bacilus, Corynebacterium, Listeria |
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Aerobic
catalase positive gram positive cocci |
Stapholococcus
Need coagulase test next to determine subtypes |
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Aerobic
catalase negative gram positive cocci |
streptococcus (or enterococcus)
need to look at hemolysis, pyr, optochin and antigen typing |
