MICRO EXAMS Flashcards
A single ASO titer is considered to be moderately elevated if the titer is at least _____ Todd units in a child.
320 Todd Units
In addition to Enterococcus faecalis, which other streptococci will grow in 6.5% salt broth?
Group B streptococci
When streaking a throat culture on 5% sheep blood agar, stabbing the agar plate provides enhanced detection for:
Streptolysin O - subsurface hemolysis
Susceptibility testing performed on quality control organisms using a new media lot number yielded zone sizes that were too large for all antibiotics tested. The testing was repeated using media from a previously used lot number, and all zone sizes were acceptable. Which of the following best explains the unacceptable zone sizes?
The depth of the media was too thin
In a disk diffusion susceptibility test, which of the following can result if disks are placed on the inoculated media and left at room temperature for an hour before incubation?
Zones of larger diameter would result
Gram stain examination from a blood culture bottle shows dark blue, spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include:
Catalase production and coagulase test
Which of the following tests should be used to differentiate Staphylococcus aureus from Staphylococcus intermedius?
Acetoin
Streptolysin O:
Antigenic
Neufeld reaction Quellung capsular swelling replaced by
Molecular test
Tumbling motility is characteristic of:
Listeria
Peptococcus and Peptostreptococcus are both:
Anaerobic gram-positive cocci
Propionobacteria are:
Anaerobic gram-positive rods
Transgrow is a transport medium for:
Gonococci and meningococci
The unique chemical structure of the cell wall of Mycobacterium spp. is associated with the presence of:
N-glycolylmuramic acid and an increase in lipid content
The heat resistance of bacterial spores, such as those of Bacillus anthracis, is partly attributable to their dehydrated state and partly to the presence of large amounts of:
Calcium dipicolinate
The use of 0.1% fuchsin substituted for safranin in the Gram-stain procedure may enhance the visibility of the organisms:
Legionella
The Schaeffer–Fulton stain can be used for demonstration of:
Spores
The Schaeffer–Fulton stain can be used for demonstration of:
Spores
The Leifson stain can be used for demonstration of:
Flagella
Which statement correctly describes the mode of action of the antibiotic listed for modified Thayer-Martin medium?
Nystatin inhibits fungi and molds
Select the medium best suited for the recovery of Yersinia enterocolitica from a patient with gastroenteritis:
Cefsulodin–Irgasan–Novobiocin (CIN) agar
Which procedure is appropriate for culture of genital specimens in order to recover Chlamydia spp.?
Inoculate cycloheximide-treated McCoy cells
PYR test
pyrrolidonyl arylamidase
Substrate of PYR
L-pyrrolidonyl-B-naphthylamide