NURSING ANM AND GNM

NURSING EXAM QUESTIONS

MICROBIOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the cell arrangement of streptococcus species on a gram stain?
A
pairs
B
clusters
C
chains
D
circles
Explanation: 

Detailed explanation-1: -Structure. Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains. Older cultures may lose their Gram-positive character. Most streptococci are facultative anaerobes, and some are obligate (strict) anaerobes.

Detailed explanation-2: -Streptococci are coccoid bacterial cells microscopically, and stain purple (Gram-positive) when Gram staining technique is applied. They are nonmotile and non-spore forming. These cocci measure between 0.5 and 2 m in diameter.

Detailed explanation-3: -Streptococci are spherical or ovoid, and are seen in pairs or as chain-like structures under a microscope. The general shape of bacterial cells (including Streptococcus) are largely affected by the cell wall and the plane of division.

Detailed explanation-4: -Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells.

Detailed explanation-5: -Streptococcus pneumoniae cells are Gram-positive, lancet-shaped cocci (elongated cocci with a slightly pointed outer curvature). Usually, they are seen as pairs of cocci (diplococci), but they may also occur singly and in short chains. When cultured on blood agar, they are alpha hemolytic.

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