Microbiology: E. coli and Enterobacteriaceae

Enterobacteriaceae, is a family of gram-negative bacteria that is found in the intestines of humans and animals. They are facultative anaerobes, meaning they can survive with or without oxygen. Most members are harmless, but some are pathogenic, causing disease.

Enterobacteriaceae are classified based on their ability to ferment lactose, a type of sugar.

Lactose fermenting Enterobacteriaceae include: Escherichia, Klebsiella and Enterobacter.

Enterobacteriaceae can be identified using commercially prepared biochemical test kits like API 20E that can differentiate various species based on their metabolic activities.

Pseudomonas is a genus of bacteria that is oxidase positive, meaning they produce the enzyme cytochrome c oxidase. This enzyme is essential for aerobic respiration.

Pseudomonas are aerobic, meaning they require oxygen to survive.

Pseudomonas are known for causing diverse infections in various parts of the body, often in individuals with compromised immune systems. They are opportunistic pathogens.

Pseudomonas aeruginosa is one of the most common species that can cause lung infections, skin infections, and even bloodstream infections.

A group of bacteria, primarily found in the intestines of humans and animals, that are often used as indicators of fecal contamination.

E. coli is a type of gram-negative bacillus commonly found in the intestines. It can cause disease in humans.

E. coli colonies on MacConkey's agar produce a distinctive pink color due to their ability to ferment lactose.

E. coli is a facultative anaerobe, meaning it can grow with or without oxygen. It also produces a variety of enzymes that allow it to break down sugars like lactose, glucose, and maltose.

E. coli has various antigens, including O (somatic), H (flagellar), and K (capsular). These antigens play a role in its virulence and ability to cause disease.

Enteropathogenic E. coli (EPEC) strains possess specific O antigens that are associated with different types of infections. For example, serotype O157:H7 is known to cause hemorrhagic colitis.

Pili, also known as fimbriae, are hair-like structures that help E. coli adhere to the surface of cells in the body. This attachment is crucial for colonization and infection.

Endotoxin is a component of the outer membrane of E. coli. It can trigger a strong immune response that can be harmful if released in large amounts.

A type of E. coli that causes dysentery-like diarrhea by invading intestinal cells. They are non-motile and do not ferment lactose easily.

A serotype of E. coli (often O157:H7) that produces a toxin called verotoxin, causing severe bloody diarrhea (hemorrhagic colitis). It is sometimes associated with undercooked hamburgers.

Vertoxin is a toxin produced by E. coli that's similar to Shiga toxin. It's named after the Vero cells it affects in laboratory tests.

EHEC infections can lead to this life-threatening complication, characterized by anemia, low platelet count, and kidney failure. Using antibiotics to treat the diarrhea can increase the risk of this happening.

A type of E. coli that attaches to the intestinal mucosa in patches. It's known to cause diarrhea, especially in children and people with weakened immune systems.

EAEC can produce this toxin, similar to those produced by Shigella species. They also produce a substance that can destroy red blood cells (hemolysin).

The process of identifying and classifying an organism based on its characteristics, often using laboratory tests and cultures.

Treatment for E. coli infections depends on the location of the infection and the bacteria's sensitivity to different drugs. Diarrhea often doesn't require treatment, but rehydration is crucial.

A type of bacteria that causes infections like wound infections, pneumonia, and meningitis.

Proteus strains often display resistance to many common antibiotics, making treatment challenging.

Proteus bacteria are rod-shaped, highly mobile, and lack a capsule or spores.

Proteus bacteria can grow in the presence or absence of oxygen, making them adaptable to various environments.

Proteus can be identified by its characteristic swarming colonies on agar plates.

Pseudomonas aeruginosa is a common opportunistic pathogen that causes infections, particularly in individuals with weakened immune systems.

Pseudomonas aeruginosa produces a characteristic blue-green pigment called pyocyanin, which gives its colonies a distinct color and odor.

Pseudomonas aeruginosa is a versatile pathogen capable of causing infections ranging from urinary tract infections to pneumonia and even bloodstream infections.

A type of bacterial toxin found in the outer membrane of Gram-negative bacteria, released when the bacteria die or lyse. Endotoxin is a potent immune stimulant and can cause a range of harmful effects, including fever, inflammation, and even shock.

A sticky outer layer that helps bacteria adhere to surfaces, forming a biofilm. These biofilms protect bacteria from antibodies and phagocytes, making them more resistant to immune defenses.

Pseudomonas aeruginosa is a versatile pathogen, capable of causing a wide variety of infections in different parts of the body, including pneumonia, skin infections, urinary tract infections, and even bloodstream infections.

This refers to the ability of an organism to create acid from the sugar glucose through an oxidative process, meaning it uses oxygen to break down the glucose.

This is a group of enzymes (elastase and protease) produced by some bacteria, including Pseudomonas aeruginosa, that play a crucial role in breaking down tissues and facilitating bacterial invasion. Elastase attacks elastin, a protein that helps maintain the integrity of tissues, while protease breaks down proteins in general.

E. coli, Enterococcus faecalis, and CI. perfringens are types of bacteria commonly found in feces. If these bacteria are detected in a water sample, it indicates that the water has been contaminated with fecal matter.

Klebsiella pneumoniae are commonly found in the intestines and respiratory tract. They can survive in soil and water, but some strains can cause infections in humans, particularly in hospitals, due to their multi-drug resistance.

Klebsiella pneumoniae can cause infections such as lobar pneumonia, urinary tract infections, septicemia, and neonatal meningitis. These infections are often associated with hospitals and are caused by multi-drug resistant strains.

Enterobacter, Citrobacter, and Serratia are bacteria commonly found in soil, water, and feces. They can cause infections in hospitalized and immunocompromised patients, especially those undergoing invasive procedures.

Proteus species are found in soil and water, and are normal inhabitants of the human intestines. They typically only cause infections when they leave the intestines.

Proteus vulgaris and Proteus mirabilis are two common Proteus species that can cause urinary tract infections (UTIs).

Some bacteria are normal inhabitants of the human body, but they can cause infections if they leave their normal locations. This is especially true for immunocompromised individuals.

Identifying the presence of specific types of bacteria in water samples is important for assessing the risk of fecal contamination. This helps us understand the potential health risks associated with using the water.