Grams Stain, Sputum

Gram stain is a simple and rapid staining method which helps in the identification of bacteria and is the only method required for studying bacterial morphology. Gram stain helps to identify and gives clue to differentiate if the bacteria identified is pathogenic or normal flora. Gram stain sometimes detects fungi also. It classify the bacteria in to two categories that is gram positive and gram negative. Gram stain also helps knowing several other properties like growth requirements, susceptibility to antibiotics and pathogenicity. Gram stain is used along with a culture to identify if bacteria is present, whether the bacteria identified is gram positive or gram negative or contaminant and help to know the cause of a bacterial infection and what other tests may need to be needed to definitively identify the cause of infection. Fungi, including yeast, may also be detected with a Gram stain. The adequacy of the specimen is established by the presence of pus cells, mucus and epithelial cells. The pathogenic gram positive organisms in sputum are Staphylococcus aureus, Streptococcus pyogenes etc and the pathogenic gram negative organisms include H.influenzae, Klebsiella pneumonia etc.

1. How the sputum sample for gram stain collected?

Sputum sample should be collected in a sterile, leak proof, screw capped, wide mouthed container. Sample should be deeply coughed up specimen, after rinsing the mouth with plain water for few minutes. It is essential that sputum containing purulent material and destroyed tissue brought by deep cough and not saliva should be collected.

2. How is bacterial infection treated?

Antibiotics are the main treatment for bacterial infections. If there is abscess, incision and drainage is the better option.

3. How will you interpret the result?

If Gram stain test result is negative, it indicates "no organism seen, " in the sample processed and examined under microscope. If a gram stain is positive, it indicates that bacteria is identified. Further classification of bacteria is done by its staining characteristics, morphology (shape, size, arrangement, presence of other cells etc).