Gram negative Rods SGDs


Gram negative Rods SGDs, often referred to as “GNRs” in the medical field, are a broad category of bacteria that play a significant role in human health and disease. The term “gram-negative” refers to their inability to retain the violet crystal dye used in Gram staining, a common technique in microbiology, while the term “rod” describes their elongated, cylindrical shape.

Gram-negative rods exhibit significant diversity, including a wide range of genera and species. Some are harmless and even beneficial, forming part of the normal human microbiota, particularly in the gastrointestinal tract. Others, however, are pathogenic and can cause serious infections. This includes well-known pathogens such as Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, among others.

Family Enterobacteriaceae

The Enterobacteriaceae family comprises a large group of Gram-negative bacteria that commonly inhabit the gastrointestinal tract. Essential in nature’s recycling system, these bacteria have both beneficial and harmful species, playing critical roles in digestion and disease.

Genus Proteus

Belonging to the Enterobacteriaceae family, the Proteus genus comprises rod-shaped bacteria notorious for causing urinary tract infections. Its species, including Proteus mirabilis and Proteus vulgaris, are distinguished by their ability to move and change shape.


Proteus, a unique bacterium in the Enterobacteriaceae family, is often found in the human gut. However, it can also cause severe infections, particularly in the urinary tract, and displays resistance to common antibiotics.

Genus Enterobacter

Enterobacter is a significant genus of the Enterobacteriaceae family. These bacteria are typically harmless but can become opportunistic pathogens in hospital settings, causing a variety of infections from respiratory to urinary tract issues.


As a species of bacteria within the Enterobacteriaceae family, Enterobacter is often found in the human gut. Some strains, however, can cause severe hospital-acquired infections, becoming a major concern in healthcare.

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Genus Yersinia

The Yersinia genus, another member of the Enterobacteriaceae family, includes species that cause diseases like plague and gastroenteritis. Yersinia pestis, for instance, is the infamous bacterium behind the Black Death.


The bacterium Yersinia, part of the Enterobacteriaceae family, is known for its pathogenic strains causing severe diseases, such as Yersinia pestis, the instigator of plague.

Genus Shigella

The Shigella genus, also a part of the Enterobacteriaceae family, is responsible for causing Shigellosis or Bacillary Dysentery. These bacteria are often spread through contaminated food and water.


Shigella, a pathogenic bacterium belonging to the Enterobacteriaceae family, is a common cause of diarrhea worldwide. Its ability to survive harsh conditions makes it a frequent culprit in foodborne illnesses.

Genus Salmonella

This genus, within the Enterobacteriaceae family, is best known for causing food poisoning. Two species, Salmonella enterica and Salmonella bongori, include multiple serotypes that can cause illnesses in humans and animals.


It is a bacterium from the Enterobacteriaceae family infamous for causing foodborne illnesses, from minor gastroenteritis to severe typhoid fever. Salmonella can be found in raw poultry, eggs, and contaminated water.

Genus Escherichia

The Escherichia genus, a member of the Enterobacteriaceae family, is commonly found in the intestines of warm-blooded organisms. Its most well-known species, Escherichia coli or E. coli, has both harmless and pathogenic strains.

E. coli

Escherichia coli, or E. coli, is a common bacterium of the Enterobacteriaceae family. While most E. coli strains are harmless and aid digestion, some can cause severe foodborne diseases, urinary tract infections, and even life-threatening conditions like hemolytic uremic syndrome.

E. coli SGD.doc

Genus Klebsiella

The Klebsiella genus, part of the Enterobacteriaceae family, includes species like Klebsiella pneumoniae, which can cause severe lung, urinary tract, and blood infections, especially in immunocompromised individuals.


Klebsiella is a type of bacterium in the Enterobacteriaceae family. Certain strains of this bacteria, like Klebsiella pneumoniae, are known for their resistance to antibiotics and their ability to cause severe infections in humans.

Family Brucellaceae

The Brucella genus, belonging to the family Brucellaceae, includes pathogenic species that cause Brucellosis, a zoonotic disease resulting in fever, fatigue, and other symptoms. It typically spreads through the consumption of unpasteurized dairy products or direct contact with infected animals.

Genus Brucella

The Brucella genus, belonging to the family Brucellaceae, includes pathogenic species that cause Brucellosis, a zoonotic disease resulting in fever, fatigue, and other symptoms. It typically spreads through the consumption of unpasteurized dairy products or direct contact with infected animals.

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Brucella, a bacterium from the Brucellaceae family, causes the disease Brucellosis, which is transmitted to humans from animals. In humans, it leads to intermittent fevers, joint pain, and other non-specific symptoms.

Family Francisellaceae

The Francisellaceae family encompasses small, Gram-negative bacteria. It includes the Francisella genus, known for causing Tularemia or “rabbit fever,” a severe and often lethal disease in humans and animals.

Genus Francisella

The Francisella genus, a member of the Francisellaceae family, includes the highly infectious Francisella tularensis bacterium. This pathogen is responsible for Tularemia, a potentially fatal disease transmitted by ticks, deer flies, or contact with infected animals.


The bacterium Francisella, particularly the species Francisella tularensis, is the cause of Tularemia. This disease, often spread by ticks or direct contact with infected animals, can be lethal if left untreated.

Family Pasteurellaceae

The Pasteurellaceae family comprises Gram-negative bacteria typically found in the respiratory tracts of mammals and birds. Among its genera is Haemophilus, with species that can cause diseases in humans, such as pneumonia and meningitis.

Genus Haemophilus

The Haemophilus genus, part of the Pasteurellaceae family, comprises small, rod-shaped bacteria. Notable species include Haemophilus influenzae, which can lead to various diseases such as pneumonia, meningitis, and septic arthritis.

Haemophilus influenzae

Haemophilus influenzae, a bacterium of the Pasteurellaceae family, is a significant cause of bacterial infections in children. These can range from ear and respiratory infections to more severe diseases like meningitis.

Family Helicobacteraceae

The Helicobacteraceae family encompasses Gram-negative bacteria known for their spiral shape. The most infamous genus of this family is Helicobacter, which includes species such as Helicobacter pylori, associated with gastritis and gastric ulcers in humans.

Genus Helicobacter

The Helicobacter genus, part of the Helicobacteraceae family, includes Helicobacter pylori, a bacterium associated with stomach ulcers and gastritis. These bacteria are unique for their ability to thrive in the stomach’s acidic environment.

Helicobacter pylori

Helicobacter pylori: Helicobacter pylori is a bacterium of the Helicobacteraceae family. Known for its ability to survive in the stomach, it is a common cause of peptic ulcers and can contribute to the development of stomach cancer.

Family Legionellaceae

The Legionellaceae family comprises Gram-negative bacteria, including the Legionella genus. These bacteria are known for causing Legionnaires’ disease, a severe form of pneumonia, and the less severe Pontiac fever.

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Genus Legionella

The Legionella genus, part of the Legionellaceae family, includes species that can cause severe respiratory diseases in humans, such as Legionnaires’ disease. These bacteria thrive in water systems, like cooling towers and hot tubs.


Legionella, a bacterium from the Legionellaceae family, is known for causing Legionnaires’ disease, a serious type of pneumonia. It often thrives in water systems and can be contracted by inhaling water droplets containing the bacteria.

Family Alcaligenaceae

The Alcaligenaceae family encompasses several genera of Gram-negative bacteria, including Bordetella. These bacteria occupy diverse habitats, from soil and water to the respiratory tracts of mammals.

Genus Bordetella

The Bordetella genus, part of the Alcaligenaceae family, includes species known for causing respiratory diseases in humans and animals. The most well-known species, Bordetella pertussis, causes whooping cough in humans.


Bordetella, a bacterium from the Alcaligenaceae family, is best known for causing whooping cough in humans. The disease, also known as pertussis, is highly contagious and can be severe, especially in infants.

Family Pseudomonadaceae

The Pseudomonadaceae family comprises diverse Gram-negative bacteria found in various environments, from soil to water. Its most notorious genus, Pseudomonas, includes species that can cause infections in humans, particularly in those with weakened immune systems.

Genus Pseudomonas

The Pseudomonas genus, part of the Pseudomonadaceae family, includes rod-shaped bacteria that are prevalent in the environment. Some species, like Pseudomonas aeruginosa, are opportunistic pathogens that can cause severe infections, especially in hospital settings.


Pseudomonas, a bacterium from the Pseudomonadaceae family, is frequently found in the environment and can cause infections in humans. Particularly, Pseudomonas aeruginosa is a significant cause of hospital-acquired infections.

Pseudomonas SGD.doc

Family Campylobacteraceae

The Campylobacteraceae family comprises Gram-negative bacteria known for their spiral shape. The Campylobacter genus within this family is a common cause of foodborne illness worldwide.

Genus Campylobacter

The Campylobacter genus, a member of the Campylobacteraceae family, includes species such as Campylobacter jejuni, which cause gastroenteritis in humans. Infections are commonly linked to consumption of undercooked poultry or contaminated water.


Campylobacter, a bacterium from the Campylobacteraceae family, is a leading cause of foodborne illness worldwide. Most infections are associated with consuming contaminated food or water, often resulting in gastrointestinal symptoms.

Family Vibrionaceae

The Vibrionaceae family comprises Gram-negative bacteria that are commonly found in aquatic environments. The Vibrio genus within this family includes species responsible for causing cholera and other gastrointestinal illnesses.

Genus Vibrio

The Vibrio genus, part of the Vibrionaceae family, includes bacteria that cause severe diseases like cholera. Species like Vibrio cholerae and Vibrio parahaemolyticus are usually transmitted through contaminated water or undercooked seafood.


Vibrio, a bacterium from the Vibrionaceae family, is found primarily in coastal saltwater environments and can cause diseases in humans. The most notorious strain, Vibrio cholerae, is responsible for cholera, a severe diarrheal disease.

Vibrio Cholerae

Vibrio Cholerae: Vibrio cholerae, a bacterium from the Vibrionaceae family, is the pathogen responsible for cholera. It’s typically transmitted through contaminated water or food, causing severe dehydration due to rapid loss of body fluids from diarrhoea.

Vibrio Cholerae SGD.doc

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