| Front | What is the cell wall theory of gram staining ? |
| Back | In GRAM POSITIVES : Peptidoglycan is not stained by the CV but it prevents the decolorisation of CV from cytoplasm and also , Iodine which was used as mordant makes complexes with dye and these cant move from cytoplasm to outside as the pores in THICC PG layer are shrinked by alcohol.In GRAM NEGATIVES , Lipopolysachharide layer is easily dissolved by Alcohol and also due to thin layer of PG , stain can easily move out of the cytoplasm. |
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| Front | What is the advantage in identification by doing gram stain ? |
| Back | - Gives idea on what kind of biochemical tests to do next as it bpgives idea on antigen types in cell wall-Empirical treatment : by the time of gram stain , we know Bacteria shape and gram type , so broad spectrum antibiotics can be used until full report arrives.-Fastidious bac. Take time to grow in culture , hence for presumptive identification-Anaerobic bac don’t grow in normal cultures . Hence gram test giving (hence confirms presence of bacteria ) and aerobic culture negative (People may think there are no bacteria ) may implement use of Anaerobic culture methods.-Some yeast fungi also can be stained by gram stain - Gram positivesCANDIDA , CRYPTOCOCCUS-Quality of specimen : For e.g., SPUTUM SPECIMEN is good if there are more pus cells and less epithelial cells |
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| Front | Most used media in labs ? |
| Back | MacConkey and blood agar |
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