ASCP practice 124 questions WITH COMPLETE SOLUTIONS

CHROMagar MRSA agar Correct Answer: can be used to distinguish Methicillin-Sensitive Staphylococcus aureus and coagulase negative staphylococci from Methicillin-Resistant Staphylococcus aureus by the addition of oxacillin or cephamycins. In addition, each organism will produce a different color. MRSA will be detected by a mauve coloration of the bacterial colonies. A manual WBC count was performed. A TOTAL of 72 cells were counted in 4 large mm squares of a Neubauer-ruled hemacytometer. A 1:20 dilution was used. What is the calculated WBC count? Correct Answer: 3.6 x 103/µL WBC count = (dilution ratio x # of cells counted x 10) / (# mm2 area counted) Then: WBC count = (20 x 72 x 10) / (4) = 3600 WBC/µL (or 3.6 x 103 WBC/µL) Which of the following is a cause of metabolic alkalosis? A.Late-stage Salicylate poisoning B. Uncontrolled diabetes mellitus C. Renal failure D. Excessive vomiting Correct Answer: D. Excessive vomiting Metabolic alkalosis Correct Answer: caused by several conditions, of which one is excessive vomiting. Other causes are (1) loss of hydrogen ions in renal acid losses that exceed acid production from cellular metabolism, (2) disproportionate chloride loss compared with HCO3 loss (ie, the plasma concentration of HCO3 increases upon restriction to a smaller space of distribution), and (3) HCO3 administration (unusual because additional HCO3 is very quickly eliminated by the kidneys). What genotype is known to be resistant to P. vivax (malaria) merozoites? Correct Answer: Fy(a-b-) A zone of inhibition Correct Answer: is the area around an antibiotic-infused paper disk that does not show any bacterial growth. The antibiotic-impregnated on the disk will diffuse into the agar in the area surrounding the disk. If the bacteria are sensitive to the antibiotic, they cannot grow near the disk. The size of the zone is proportional to how sensitive the organism is. If the organism is resistant to the antibiotic, it will grow very close to the disk. Resistance Correct Answer: is an interpretive category of a susceptibility test that indicates the antimicrobial agent is not appropriate for treatment. Breakpoints Correct Answer: are the specific concentrations of antimicrobial agents that differentiate the interpretations for susceptibility testing into the sensitive, intermediate or resistant categories.