Overview

Gram stain is used to classify bacteria based on their forms, sizes, cellular morphologies and color stained by the Gram stain procedure. Gram stain is used for quick evaluation of the specimen and culture material before further testing is performed for infection detection and diagnosis.

Bacteria stain either gram-positive or gram-negative on the basis of differences in their cell wall compositions and architectures. Gram-positive species have a thick peptidoglycan layer and large amounts of teichoic acids; they are unaffected by alcohol decolorization and retain the initial stain, appearing deep violet if their cell walls are undamaged by age, antimicrobial agents, or other factors. Gram-negative species have a single peptidoglycan layer attached to an asymmetric lipopolysaccharide-phospholipid bilayer outer membrane interspersed with protein; the outer membrane is damaged by the alcohol decolorizer, allowing the crystal violet-iodine complex to leak out and be replaced by the counterstain.

Using Gram stain to detect the presence of bacteria and differentiate if an infection is caused by Gram-positive or Gram-negative bacteria often will give enough information to a health provider to initiate treatment with an appropriate antibiotic while waiting for more specific tests, such as a culture, to be completed. In addition, gram stain can detect other elements including white blood cells (WBC), yeast and epithelial cell. Detecting WBC is also important as they are frequently present with a bacterial, parasite or fungal infection.

A Gram stain may also be performed as part of the culture procedure. If bacteria are grown by culture, a Gram stain is performed to help determine the type of bacteria present and to help determine what other tests may need to be performed to definitively identify the cause of infection. Gram stain is the most valuable test for acute infections such as bacterial meningitis and blood cultures as it gives a quick result for initial antibiotic therapy until more testing is obtained.

Clinical Utility
  • As an aid in diagnosis of meningitis
  • As an aid in diagnosis of sepsis
  • As an aid in diagnosis of respiratory infection
  • As an aid in diagnosis of wound infection
  • As an aid in diagnosis of yeast infection
  • As an aid in diagnosis of variety of infections

Interpretation

Positive gram stain indicates infection with gram positive or gram negative bacteria. Results will differentiate gram positive and gram negative bacteria based on morphology, color and shape. It will describe presence of multiple bacteria, cells, white blood cells, yeast and other elements.

Reference Ranges

Usual Vaginal Flora present 
Nugent score: 0-3

Methodology

Gram Stain and microscopy.

Specimen Collection

Biopsies, sputum, tracheal aspirates, bronchial wash, nasal swab, throat swab, body fluids, urine, variety of discharges, wounds

Stability:

The best results are obtained from fresh specimens. Stability depends on the specimen type. Some swabs can have stability up to 48 hours.

Additional Testing

Bacterial culture from different sources, susceptibility testing on each isolate if detected by culture.

Turnaround Time

1-3 days.

CPT
87205$ 4.27

ICD10
A01.03Typhoid pneumonia
A02.22Salmonella pneumonia
A06.5Amebic lung abscess
A15.0Tuberculosis of lung
A15.7Primary respiratory tuberculosis
A20.2Pneumonic plague
A37Whooping cough
A37.00Whooping cough due to Bordetella pertussis without pneumonia
A37.01Whooping cough due to Bordetella pertussis with pneumonia
A37.10Whooping cough due to Bordetella parapertussis without pneumonia
A37.11Whooping cough due to Bordetella parapertussis with pneumonia
A37.80Whooping cough due to other Bordetella species without pneumonia
A37.81Whooping cough due to other Bordetella species with pneumonia
A37.90Whooping cough, unspecified species without pneumonia
A37.91Whooping cough, unspecified species with pneumonia
A40Streptococcal sepsis
A40.3Sepsis due to Streptococcus pneumoniae
A48Other bacterial diseases, not elsewhere classified
A48.1Legionnaires' disease
A48.2Nonpneumonic Legionnaires' disease [Pontiac fever]
A49Bacterial infection of unspecified site
A49.2Hemophilus influenzae infection, unspecified site
A50.04Early congenital syphilitic pneumonia
A52.72Syphilis of lung and bronchus
A54.84Gonococcal pneumonia
B01.2Varicella pneumonia
B05.2Measles complicated by pneumonia
B06.81Rubella pneumonia
B77.81Ascariasis pneumonia
B95.3Streptococcus pneumoniae as the cause of diseases classified elsewhere
B96Other bacterial agents as the cause of diseases classified elsewhere
B96.0Mycoplasma pneumoniae [M. pneumoniae] as the cause of diseases classified elsewhere
B96.1Klebsiella pneumoniae [K. pneumoniae] as the cause of diseases classified elsewhere
B96.3Hemophilus influenzae [H. influenzae] as the cause of diseases classified elsewhere
C46.5Kaposi's sarcoma of lung
C78.0Secondary malignant neoplasm of lung
D14.3Benign neoplasm of bronchus and lung
D86.0Sarcoidosis of lung
D86.2Sarcoidosis of lung with sarcoidosis of lymph nodes
G00Bacterial meningitis, not elsewhere classified
G00.0Hemophilus meningitis
G44.83Primary cough headache
J09Influenza due to certain identified influenza viruses
J09.X1Influenza due to identified novel influenza A virus with pneumonia
J10.1Influenza due to other identified influenza virus with other respiratory manifestations
J12Viral pneumonia, not elsewhere classified
J12.0Adenoviral pneumonia
J12.1Respiratory syncytial virus pneumonia
J12.2Parainfluenza virus pneumonia
J12.3Human metapneumovirus pneumonia
J12.8Other viral pneumonia
J12.81Pneumonia due to SARS-associated coronavirus
J12.89Other viral pneumonia
J12.9Viral pneumonia, unspecified
J13Pneumonia due to Streptococcus pneumoniae
J14Pneumonia due to Hemophilus influenzae
J15Bacterial pneumonia, not elsewhere classified
J15.0Pneumonia due to Klebsiella pneumoniae
J15.1Pneumonia due to Pseudomonas
J15.2Pneumonia due to staphylococcus
J15.20Pneumonia due to staphylococcus, unspecified
J15.21Pneumonia due to staphylococcus aureus
J15.211Pneumonia due to Methicillin susceptible Staphylococcus aureus
J15.212Pneumonia due to Methicillin resistant Staphylococcus aureus
J15.29Pneumonia due to other staphylococcus
J15.3Pneumonia due to streptococcus, group B
J15.4Pneumonia due to other streptococci
J15.5Pneumonia due to Escherichia coli
J15.6Pneumonia due to other Gram-negative bacteria
J15.7Pneumonia due to Mycoplasma pneumoniae
J15.8Pneumonia due to other specified bacteria
J15.9Unspecified bacterial pneumonia
J16Pneumonia due to other infectious organisms, not elsewhere classified
J16.0Chlamydial pneumonia
J16.8Pneumonia due to other specified infectious organisms
J17Pneumonia in diseases classified elsewhere
J18Pneumonia, unspecified organism
J18.0Bronchopneumonia, unspecified organism
J18.1Lobar pneumonia, unspecified organism
J18.2Hypostatic pneumonia, unspecified organism
J18.8Other pneumonia, unspecified organism
J18.9Pneumonia, unspecified organism
J20Acute bronchitis
J20.0Acute bronchitis due to Mycoplasma pneumoniae
J20.1Acute bronchitis due to Hemophilus influenzae
J20.5Acute bronchitis due to respiratory syncytial virus
J20.9Acute bronchitis, unspecified
J22Unspecified acute lower respiratory infection
J40Bronchitis, not specified as acute or chronic
J41Simple and mucopurulent chronic bronchitis
J41.0Simple chronic bronchitis
J42Unspecified chronic bronchitis
J43Emphysema
J44Other chronic obstructive pulmonary disease
J44.0Chronic obstructive pulmonary disease with (acute) lower respiratory infection
J44.1Chronic obstructive pulmonary disease with (acute) exacerbation
J44.9Chronic obstructive pulmonary disease, unspecified
J45Asthma
J45.20Mild intermittent asthma, uncomplicated
J45.991Cough variant asthma
J47Bronchiectasis
J47.0Bronchiectasis with acute lower respiratory infection
J63.0Aluminosis (of lung)
J63.3Graphite fibrosis (of lung)
J67.0Farmer's lung
J67.2Bird fancier's lung
J67.4Maltworker's lung
J70.3Chronic drug-induced interstitial lung disorders
J80Acute respiratory distress syndrome
J81Pulmonary edema
J82.81Chronic eosinophilic pneumonia
J82.82Acute eosinophilic pneumonia
J84Other interstitial pulmonary diseases
J84.11Idiopathic interstitial pneumonia
J84.111Idiopathic interstitial pneumonia, not otherwise specified
J84.115Respiratory bronchiolitis interstitial lung disease
J84.116Cryptogenic organizing pneumonia
J84.117Desquamative interstitial pneumonia
J84.2Lymphoid interstitial pneumonia
J85Abscess of lung and mediastinum
J85.1Abscess of lung with pneumonia
J85.2Abscess of lung without pneumonia
J95.1Acute pulmonary insufficiency following thoracic surgery
J95.2Acute pulmonary insufficiency following nonthoracic surgery
J95.3Chronic pulmonary insufficiency following surgery
J95.8Other intraoperative and postprocedural complications and disorders of respiratory system, not elsewhere classified
J95.851Ventilator associated pneumonia
J96.0Acute respiratory failure
J98.4Other disorders of lung
M05.1Rheumatoid lung disease with rheumatoid arthritis
M32.13Lung involvement in systemic lupus erythematosus
M34.81Systemic sclerosis with lung involvement
P22Respiratory distress of newborn
P23Congenital pneumonia
P23.0Congenital pneumonia due to viral agent
P23.1Congenital pneumonia due to Chlamydia
P23.2Congenital pneumonia due to staphylococcus
P23.3Congenital pneumonia due to streptococcus, group B
P23.4Congenital pneumonia due to Escherichia coli
P23.5Congenital pneumonia due to Pseudomonas
P23.6Congenital pneumonia due to other bacterial agents
P23.8Congenital pneumonia due to other organisms
Q33.0Congenital cystic lung
Q33.6Congenital hypoplasia and dysplasia of lung
Q33.8Other congenital malformations of lung
R05Cough
R06.03Acute respiratory distress
S27.30Unspecified injury of lung
T86.81Complications of lung transplant
T86.811Lung transplant failure
T86.812Lung transplant infection
T86.819Unspecified complication of lung transplant
Z16Resistance to antimicrobial drugs
Z85.11Personal history of malignant neoplasm of bronchus and lung
Z87.01Personal history of pneumonia (recurrent)
Z94.2Lung transplant status

Additional ICD10
A06.5Amebic lung abscess
A37.0Whooping cough due to Bordetella pertussis
A37.00Whooping cough due to Bordetella pertussis without pneumonia
A37.01Whooping cough due to Bordetella pertussis with pneumonia
A37.1Whooping cough due to Bordetella parapertussis
A37.10Whooping cough due to Bordetella parapertussis without pneumonia
A37.11Whooping cough due to Bordetella parapertussis with pneumonia
A37.8Whooping cough due to other Bordetella species
A37.80Whooping cough due to other Bordetella species without pneumonia
A37.81Whooping cough due to other Bordetella species with pneumonia
A37.9Whooping cough, unspecified species
A37.90Whooping cough, unspecified species without pneumonia
A37.91Whooping cough, unspecified species with pneumonia
A48.0Gas gangrene
A48.1Legionnaires' disease
A48.2Nonpneumonic Legionnaires' disease [Pontiac fever]
A48.3Toxic shock syndrome
A48.4Brazilian purpuric fever
A48.5Other specified botulism
A48.51Infant botulism
A48.52Wound botulism
A48.8Other specified bacterial diseases
A49.0Staphylococcal infection, unspecified site
A49.01Methicillin susceptible Staphylococcus aureus infection, unspecified site
A49.02Methicillin resistant Staphylococcus aureus infection, unspecified site
A49.1Streptococcal infection, unspecified site
A49.2Hemophilus influenzae infection, unspecified site
A49.3Mycoplasma infection, unspecified site
A49.8Other bacterial infections of unspecified site
A49.9Bacterial infection, unspecified
B95.3Streptococcus pneumoniae as the cause of diseases classified elsewhere
B96.0Mycoplasma pneumoniae [M. pneumoniae] as the cause of diseases classified elsewhere
B96.1Klebsiella pneumoniae [K. pneumoniae] as the cause of diseases classified elsewhere
B96.2Escherichia coli [E. coli ] as the cause of diseases classified elsewhere
B96.20Unspecified Escherichia coli [E. coli] as the cause of diseases classified elsewhere
B96.21Shiga toxin-producing Escherichia coli [E. coli] [STEC] O157 as the cause of diseases classified elsewhere
B96.22Other specified Shiga toxin-producing Escherichia coli [E. coli] [STEC] as the cause of diseases classified elsewhere
B96.23Unspecified Shiga toxin-producing Escherichia coli [E. coli] [STEC] as the cause of diseases classified elsewhere
B96.29Other Escherichia coli [E. coli] as the cause of diseases classified elsewhere
B96.3Hemophilus influenzae [H. influenzae] as the cause of diseases classified elsewhere
B96.4Proteus (mirabilis) (morganii) as the cause of diseases classified elsewhere
B96.5Pseudomonas (aeruginosa) (mallei) (pseudomallei) as the cause of diseases classified elsewhere
B96.6Bacteroides fragilis [B. fragilis] as the cause of diseases classified elsewhere
B96.7Clostridium perfringens [C. perfringens] as the cause of diseases classified elsewhere
B96.8Other specified bacterial agents as the cause of diseases classified elsewhere
B96.81Helicobacter pylori [H. pylori] as the cause of diseases classified elsewhere
B96.82Vibrio vulnificus as the cause of diseases classified elsewhere
B96.89Other specified bacterial agents as the cause of diseases classified elsewhere
G00.0Hemophilus meningitis
G00.1Pneumococcal meningitis
G00.2Streptococcal meningitis
G00.3Staphylococcal meningitis
G00.8Other bacterial meningitis
G00.9Bacterial meningitis, unspecified
G44.83Primary cough headache
J09.XInfluenza due to identified novel influenza A virus
J09.X1Influenza due to identified novel influenza A virus with pneumonia
J09.X2Influenza due to identified novel influenza A virus with other respiratory manifestations
J09.X3Influenza due to identified novel influenza A virus with gastrointestinal manifestations
J09.X9Influenza due to identified novel influenza A virus with other manifestations
J10.0Influenza due to other identified influenza virus with pneumonia
J10.00Influenza due to other identified influenza virus with unspecified type of pneumonia
J10.01Influenza due to other identified influenza virus with the same other identified influenza virus pneumonia
J10.08Influenza due to other identified influenza virus with other specified pneumonia
J11.0Influenza due to unidentified influenza virus with pneumonia
J11.00Influenza due to unidentified influenza virus with unspecified type of pneumonia
J11.08Influenza due to unidentified influenza virus with specified pneumonia
J12.0Adenoviral pneumonia
J12.1Respiratory syncytial virus pneumonia
J12.2Parainfluenza virus pneumonia
J12.3Human metapneumovirus pneumonia
J12.8Other viral pneumonia
J12.81Pneumonia due to SARS-associated coronavirus
J12.89Other viral pneumonia
J12.9Viral pneumonia, unspecified
J15.0Pneumonia due to Klebsiella pneumoniae
J15.1Pneumonia due to Pseudomonas
J15.2Pneumonia due to staphylococcus
J15.20Pneumonia due to staphylococcus, unspecified
J15.21Pneumonia due to staphylococcus aureus
J15.211Pneumonia due to Methicillin susceptible Staphylococcus aureus
J15.212Pneumonia due to Methicillin resistant Staphylococcus aureus
J15.29Pneumonia due to other staphylococcus
J15.3Pneumonia due to streptococcus, group B
J15.4Pneumonia due to other streptococci
J15.5Pneumonia due to Escherichia coli
J15.6Pneumonia due to other Gram-negative bacteria
J15.7Pneumonia due to Mycoplasma pneumoniae
J15.8Pneumonia due to other specified bacteria
J15.9Unspecified bacterial pneumonia
J16.0Chlamydial pneumonia
J16.8Pneumonia due to other specified infectious organisms
J18.0Bronchopneumonia, unspecified organism
J18.1Lobar pneumonia, unspecified organism
J18.2Hypostatic pneumonia, unspecified organism
J18.8Other pneumonia, unspecified organism
J18.9Pneumonia, unspecified organism
J20.0Acute bronchitis due to Mycoplasma pneumoniae
J20.1Acute bronchitis due to Hemophilus influenzae
J20.2Acute bronchitis due to streptococcus
J20.3Acute bronchitis due to coxsackievirus
J20.4Acute bronchitis due to parainfluenza virus
J20.5Acute bronchitis due to respiratory syncytial virus
J20.6Acute bronchitis due to rhinovirus
J20.7Acute bronchitis due to echovirus
J20.8Acute bronchitis due to other specified organisms
J20.9Acute bronchitis, unspecified
J41.0Simple chronic bronchitis
J41.1Mucopurulent chronic bronchitis
J41.8Mixed simple and mucopurulent chronic bronchitis
J43.0Unilateral pulmonary emphysema [MacLeod's syndrome]
J43.1Panlobular emphysema
J43.2Centrilobular emphysema
J43.8Other emphysema
J43.9Emphysema, unspecified
J44.0Chronic obstructive pulmonary disease with (acute) lower respiratory infection
J44.1Chronic obstructive pulmonary disease with (acute) exacerbation
J44.9Chronic obstructive pulmonary disease, unspecified
J45.2Mild intermittent asthma
J45.20Mild intermittent asthma, uncomplicated
J45.21Mild intermittent asthma with (acute) exacerbation
J45.22Mild intermittent asthma with status asthmaticus
J45.3Mild persistent asthma
J45.30Mild persistent asthma, uncomplicated
J45.31Mild persistent asthma with (acute) exacerbation
J45.32Mild persistent asthma with status asthmaticus
J45.4Moderate persistent asthma
J45.40Moderate persistent asthma, uncomplicated
J45.41Moderate persistent asthma with (acute) exacerbation
J45.42Moderate persistent asthma with status asthmaticus
J45.5Severe persistent asthma
J45.50Severe persistent asthma, uncomplicated
J45.51Severe persistent asthma with (acute) exacerbation
J45.52Severe persistent asthma with status asthmaticus
J45.9Other and unspecified asthma
J45.90Unspecified asthma
J45.901Unspecified asthma with (acute) exacerbation
J45.902Unspecified asthma with status asthmaticus
J45.909Unspecified asthma, uncomplicated
J45.99Other asthma
J45.990Exercise induced bronchospasm
J45.991Cough variant asthma
J45.998Other asthma
J47.0Bronchiectasis with acute lower respiratory infection
J47.1Bronchiectasis with (acute) exacerbation
J47.9Bronchiectasis, uncomplicated
J81.0Acute pulmonary edema
J81.1Chronic pulmonary edema
J84.0Alveolar and parieto-alveolar conditions
J84.01Alveolar proteinosis
J84.02Pulmonary alveolar microlithiasis
J84.03Idiopathic pulmonary hemosiderosis
J84.09Other alveolar and parieto-alveolar conditions
J84.1Other interstitial pulmonary diseases with fibrosis
J84.10Pulmonary fibrosis, unspecified
J84.11Idiopathic interstitial pneumonia
J84.111Idiopathic interstitial pneumonia, not otherwise specified
J84.112Idiopathic pulmonary fibrosis
J84.113Idiopathic non-specific interstitial pneumonitis
J84.114Acute interstitial pneumonitis
J84.115Respiratory bronchiolitis interstitial lung disease
J84.116Cryptogenic organizing pneumonia
J84.117Desquamative interstitial pneumonia
J84.17Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere
J84.170Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
J84.178Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere
J84.2Lymphoid interstitial pneumonia
J84.8Other specified interstitial pulmonary diseases
J84.81Lymphangioleiomyomatosis
J84.82Adult pulmonary Langerhans cell histiocytosis
J84.83Surfactant mutations of the lung
J84.84Other interstitial lung diseases of childhood
J84.841Neuroendocrine cell hyperplasia of infancy
J84.842Pulmonary interstitial glycogenosis
J84.843Alveolar capillary dysplasia with vein misalignment
J84.848Other interstitial lung diseases of childhood
J84.89Other specified interstitial pulmonary diseases
J84.9Interstitial pulmonary disease, unspecified
J85.0Gangrene and necrosis of lung
J85.1Abscess of lung with pneumonia
J85.2Abscess of lung without pneumonia
J85.3Abscess of mediastinum
P22.0Respiratory distress syndrome of newborn
P22.1Transient tachypnea of newborn
P22.8Other respiratory distress of newborn
P22.9Respiratory distress of newborn, unspecified
P23.0Congenital pneumonia due to viral agent
P23.1Congenital pneumonia due to Chlamydia
P23.2Congenital pneumonia due to staphylococcus
P23.3Congenital pneumonia due to streptococcus, group B
P23.4Congenital pneumonia due to Escherichia coli
P23.5Congenital pneumonia due to Pseudomonas
P23.6Congenital pneumonia due to other bacterial agents
P23.8Congenital pneumonia due to other organisms
P23.9Congenital pneumonia, unspecified
Z16.1Resistance to beta lactam antibiotics
Z16.10Resistance to unspecified beta lactam antibiotics
Z16.11Resistance to penicillins
Z16.12Extended spectrum beta lactamase (ESBL) resistance
Z16.19Resistance to other specified beta lactam antibiotics
Z16.2Resistance to other antibiotics
Z16.20Resistance to unspecified antibiotic
Z16.21Resistance to vancomycin
Z16.22Resistance to vancomycin related antibiotics
Z16.23Resistance to quinolones and fluoroquinolones
Z16.24Resistance to multiple antibiotics
Z16.29Resistance to other single specified antibiotic
Z16.3Resistance to other antimicrobial drugs
Z16.30Resistance to unspecified antimicrobial drugs
Z16.31Resistance to antiparasitic drug(s)
Z16.32Resistance to antifungal drug(s)
Z16.33Resistance to antiviral drug(s)
Z16.34Resistance to antimycobacterial drug(s)
Z16.341Resistance to single antimycobacterial drug
Z16.342Resistance to multiple antimycobacterial drugs
Z16.35Resistance to multiple antimicrobial drugs
Z16.39Resistance to other specified antimicrobial drug
Z87.01Personal history of pneumonia (recurrent)
Z87.09Personal history of other diseases of the respiratory system

References
  • J Infect. 2009 Aug;59(2):83-9. [PMID:19564045]
  • Bacteriological Reviews. 1884; 24 (3): 261–265. [PMID:13685217]
  • Biotechnic & Histochemistry. 2001;76 (3): 111–118. [PMID:11475313]
  • Biotech Histochem. 1996 May;71(3):145-51. [PMID:8724440]
  • Bailey & Scott's Diagnostic Microbiology, 13th Edition; 2013. ISBN-13: 978-0323083300.