- The purpose of heat fixing a bacterial smear is to:
- a) prevent cells from being washed off during staining ✅
- b) causes the cells to absorb the stain more easily
- c) provide a warm temperature for the bacteria to grow
- d) make the cells visible under the microscope
- e) destroy the bacterial cell wall
- The site of a specimen must be written on a swab container:
- a) to warn staff about a possible pathogen
- b) only if time permits – it is always on the requisition
- c) to determine suitable agar and atmospheric requirements ✅
- d) to determine the o.h.i.p. fee
- e) a, b, c, d and e
- Identify the correct sequence of steps on the gram stain procedure:
- a) primary stain, secondary stain, mordant, decolorizing
- b) mordant, primary stain, decolorizing, counterstain
- c) counterstain, mordant, primary stain, decolorizing
- d) primary stain, mordant, decolorizing, counterstain ✅
- e) none of the above
- How should commercially prepared culture plates be stored:
- a) in the freezer until several hours before use
- b) inverted to prevent condensation dripping on the media ✅
- c) at room temperature in a dark area of the lab
- d) at a temperature of 2°C – 4°C
- e) b & d ✅
- Which Gram stain reagent acts as a mordant to bind the stain to the bacteria:
- a) Lugol’s iodine
- b) safranin
- c) acetone-alcohol
- d) Gram’s iodine ✅
- e) crystal violet
- Identify the false statement regarding blood culture collection:
- a) the site is cleaned with betadine and alcohol
- b) an arterial sample is collected
- c) an aerobic specimen is required
- d) blood culture tubes are always drawn first
- e) the specimens are never refrigerated
- Susceptibility testing:
- a) measures how fast a micro-organism can be destroyed
- b) identifies the types of micro-organisms in the specimen
- c) determines growth requirements of organisms
- d) produces a pure culture
- e) identifies the appropriate antibiotic needed to kill the micro-organism ✅
- Identify the false statement when a specimen is cultured:
- a) the equipment required is a loop and a direct flame
- b) the media is brought to room temperature before use
- c) the media selected is dependent on the type of specimen
- d) the loop is sterilized prior to inoculation
- e) the petri lid is placed upright to the bench to prevent contamination ✅
- Which statement is false when a Gram stain is performed:
- a) distilled water is used for the washing steps
- b) acetone-alcohol decolorizes gram-negative bacteria
- c) safranin stains the gram-negative bacteria red
- d) Gram’s iodine is used to bind the primary stain
- e) crystal violet stains the gram-positive bacteria purple
- Which is most commonly used for protection when processing swabs, body fluid or blood:
- a) fume hood
- b) class I laminar flow hood
- c) class II laminar flow hood ✅
- d) class III laminar flow hood
- e) glove box
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