This expiremwnt was carried out .In no less than 30 words what can uconcluded from this lab TESTS FOR GRAM POSITIVEORGANISMSPART IIExperiment 8C lab period 2We will continue to introduce new tests used for gram-positive organism.Be sure to review results for BAP, MSA, and Coagulase tests from last labperiodAntibiotic Susceptibility TestsTwo separate tests for antibiotic susceptibility will performed. Thesetests are used to differentiate between alpha and beta hemolyticorganisms. Alpha hemolytic organisms (Streptococcus pneumoniae andStreptococcus mitis) are tested for their susceptibility to Taxos P(optochin). The beta hemolytic organisms (Streptococcus pyogenes andStreptococcus agalactiae) are tested with Taxos A (bacitracin). A zone ofinhibition of growth around the Taxos disc indicates that the organism issusceptible/sensitive to that antibiotic.Taxos A (bacitracin sensitivity testing)This is a differential test used to distinguish between organismssensitive to the antibiotic bacitracin and those not. Bacitracin is a peptideantibiotic produced by Bacillus subtilis. It inhibits cell wall synthesis anddisrupts the cell membrane. This test is commonly used to distinguishbetween the b-hemolytic streptococci: Streptococcusagalactiae (bacitracin resistant) and Streptococcus pyogenes (bacitracinsensitive). The plate below was streaked with Streptococcus pyogenes;notice the large zone of inhibition surrounding the disk.Taxos P (optochin sensitivity testing)This is a differential test used to distinguish between organismssensitive to the antibiotic optochin and those not. This test is used todistinguish Streptococcus pneumoniae (optochin sensitive) from other a-hemolytic streptococci (optochin resistant).Procedure:|||O 8:38ResultsObserve the results for both Taxos A and P. Streptococcus pyogenes willbe sensitive to bacitracin and Streptococcus pneumonia will be sensitiveto optochin.Streptococcus pyogenesNitrate TestThis is a differential medium. It is used to determine if an organism iscapable of reducing nitrate (NO3-) to nitrite (NO₂) or other nitrogenouscompounds via the action of the enzyme nitratase (also called nitratereductase). This test is important in the identification of both grampositive and gram negative species.After incubation, these tubes are first inspected for the presence of gasin the Durham tube. In the case of non-fermenters, this is indicative ofreduction of nitrate to nitrogen gas. However, in many cases gas isproduced by fermentation and further testing is necessary to determineif reduction of nitrate has occurred. This further testing includes theaddition of sulfanilic acid (often called nitrate I) and dimethyl-alpha-napthalamine (nitrate II). If nitrite is present in the media, then it will reactwith nitrate I and nitrate II to form a red compound. This is considered apositive result. If no red color forms upon addition of nitrate I and II, thisindicates that either the NO3 has not been converted to NO₂ (a negativeresult), or that NO3¯ was converted to NO₂ and then immediately reducedto some other, undetectable form of nitrogen (also a positive result). Inorder to determine which of the preceding is the case, elemental zinc isadded to the broth. Zinc will convert any remaining NO3 to NO₂ thusallowing nitrate I and nitrate II to react with the NO₂ and form the redpigment (a verified negative result). If no color change occurs uponaddition of zinc then this means that the NO3 was converted to NO₂ andthen was converted to some other undetectable form of nitrogen (apositive result).If the nitrate broth turns red (tubes pictured in the center) after nitrate Iand nitrate II are added, this color indicates a positive result. If instead,the tube turne rod (tubo pictured on the left) after the addition of In this|||

Antibiotics are substances produced by microorganisms that can kill bacteria. The word hemolysis…

TESTS FOR GRAM POSITIVE ORGANISMS PART II Experiment 8C lab period 2 We will continue to introduce new tests used for gram-positive organism. Be sure to review results for BAP, MSA, and Coagulase tests from last lab period Antibiotic Susceptibility Tests Two separate tests for antibiotic susceptibility will performed. These tests are used to differentiate between alpha and beta hemolytic organisms. Alpha hemolytic organisms (Streptococcus pneumoniae and Streptococcus mitis) are tested for their susceptibility to Taxos P (optochin). The beta hemolytic organisms (Streptococcus pyogenes and Streptococcus agalactiae) are tested with Taxos A (bacitracin). A zone of inhibition of growth around the Taxos disc indicates that the organism is susceptible/sensitive to that antibiotic. Taxos A (bacitracin sensitivity testing) This is a differential test used to distinguish between organisms sensitive to the antibiotic bacitracin and those not. Bacitracin is a peptide antibiotic produced by Bacillus subtilis. It inhibits cell wall synthesis and disrupts the cell membrane. This test is commonly used to distinguish between the b-hemolytic streptococci: Streptococcus agalactiae (bacitracin resistant) and Streptococcus pyogenes (bacitracin sensitive). The plate below was streaked with Streptococcus pyogenes; notice the large zone of inhibition surrounding the disk. Taxos P (optochin sensitivity testing) This is a differential test used to distinguish between organisms sensitive to the antibiotic optochin and those not. This test is used to distinguish Streptococcus pneumoniae (optochin sensitive) from other a- hemolytic streptococci (optochin resistant). Procedure:

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...