Microbial Classification and Bacterial Morphology

Quinolones inhibit DNA synthesis by blocking DNA gyrase, a bacterial enzyme.

Nitrofurantoin damages bacterial DNA.

Rifampicin inhibits RNA synthesis by binding to RNA polymerase in bacteria.

A type of inhibition where a drug competes with an essential metabolite for the same enzyme.

Sulphonamides are similar to PABA (an essential metabolite for folic acid synthesis) creating a competitive inhibition.

Trimethoprim inhibits an enzyme (dihydrofolic acid reductase) crucial for bacterial nucleotide synthesis.

Using antibiotics before expected infection to lower infection risk.

Bacteria produce enzymes that break down/inactivate antibiotics (like penicillinases).

An ideal antimicrobial agent should kill or inhibit the growth of a microorganism without harming the host's cells.

Antibiotics like penicillin, cephalosporins, and vancomycin interfere with cell wall synthesis by inhibiting peptidoglycan production.

Penicillin and cephalosporins (β-lactams) block the formation of peptidoglycan, a key component of the bacterial cell wall.

Polymyxins, amphotericin B, and nystatin disrupt bacterial cell membranes, leading to leakage of essential components and cell death.

Many drugs inhibit protein synthesis in bacteria by targeting their ribosomes, which are different from human ribosomes.

Bacteria have 70S ribosomes (with 50S and 30S subunits), making them different from human cells which have 80S ribosomes.

These drugs inhibit bacterial protein synthesis by targeting the 50S subunit of the bacterial ribosome.

Tetracycline inhibits bacterial protein synthesis by targeting the 30S subunit of the bacterial ribosome.

Active against a wide range of microorganisms, both gram-positive and gram-negative, e.g., tetracyclines, chloramphenicol, and ampicillin.

Active against one or a very few types of microorganisms, e.g., vancomycin against specific gram-positive cocci.

Microorganisms develop mechanisms to resist the effects of antibiotics, like altering their permeability to the drug, target sites, or metabolic pathways.

Microorganisms modify the structure of the target site where the antibiotic binds, preventing it from working effectively.

Using multiple antibiotics together offers benefits like treating severe infections, mixed infections, chronic conditions, and delaying drug resistance.

Combining antibiotics has drawbacks such as increased cost, side effects, drug interactions, and potential for superinfections.

The combined effect of two drugs is greater than the sum of their individual effects.

Two drugs work in a sequence, blocking different points in a metabolic pathway.

One drug helps the other drug enter the bacteria more effectively.

One drug prevents bacterial enzymes from breaking down the other drug, making it last longer.

Microorganisms that live naturally in and on our bodies, usually without causing harm.

The close and often long-term interaction between two different organisms.

Organisms that can grow both in the presence and absence of oxygen.

Organisms that require a low concentration of oxygen for growth.

Pigments produced by bacteria and localized within the cell.

Pigments produced by bacteria and released outside the cell.

Harmful substances produced by bacteria that can cause disease.

The way a pathogen leaves an infected host. Examples include urine, feces, respiratory secretions, blood, and genital discharges.

A relationship where a pathogen lives in a host without causing harm or symptoms. Example: Commensal bacteria in the mouth.

A relationship where a pathogen invades host tissues, elicits an immune response, but causes minimal damage and no noticeable symptoms.

A relationship where a pathogen invades host tissues, triggers the immune system, and causes significant damage, resulting in observable symptoms.

An individual who harbors a pathogen, multiplies it, but shows no outward symptoms. They can still transmit the pathogen.

The ability of a microorganism to cause disease.

The degree of pathogenicity; how easily and effectively a microorganism can cause disease.

Specific surface structures on bacteria that help them attach to host cells.

An enzyme produced by some pathogens that breaks down collagen, a protein found in tissues.

Using drugs to target and eliminate microorganisms without harming the host.

Most bacteria grow well in normal atmospheric CO2 levels, but some require higher concentrations for optimal growth. This is important for their metabolic processes.

Every bacterial species has a characteristic range of temperatures for growth. The minimum temperature is the lowest at which growth occurs, the maximum is the highest, and the optimal temperature is the one at which growth is most rapid.

Some bacteria produce pigments that give them their characteristic color. These pigments can be located inside the cell (endopigment) or released outside (exopigment).

Exotoxins are proteins released by bacteria that can cause disease. Endotoxins are components of the bacterial cell wall that are released when the bacteria dies.

A person who harbors a pathogenic organism and can spread it to others, but shows no symptoms themselves.

Proteins released by bacteria that can cause disease. They're often highly specific in their effects and can be very potent.

Components of the bacterial cell wall that are released when the bacteria dies. These are typically lipopolysaccharides and can cause severe symptoms.

The spread of infection through direct contact, such as touching, kissing, or sexual intercourse.

The spread of infection through tiny particles suspended in the air

An infection that is spread from a vertebrate animal to a human.

The ways in which pathogens enter the body.

Organism that only causes disease when the host's immune system is weakened.

Transmission of disease through contact with infected feces and then with the mouth.

A microbe capable of causing disease in a healthy individual with intact immune defenses.

The multiplication of an infectious agent within the body, which may or may not cause symptoms.

The development of signs and symptoms due to a sufficient amount of damage caused by a pathogen.

Quinolones are antibiotics that block DNA gyrase, an enzyme essential for bacterial DNA replication. This prevents the bacteria from making copies of their genetic material and ultimately leads to their death.

Rifampicin is an antibiotic that binds to RNA polymerase, the enzyme responsible for making RNA from DNA. This prevents bacteria from transcribing their genetic code and ultimately stops protein synthesis, leading to their death.

Sulphonamides and trimethoprim are antibiotics that interfere with folic acid synthesis in bacteria. Folic acid is necessary for the production of essential molecules like DNA and RNA.

Antimicrobial prophylaxis refers to using antibiotics before a potential infection to reduce the risk of getting sick. This approach is taken when an individual is at risk of developing an infection, such as before surgical procedures.

Bacteria can develop resistance against antibiotics by producing enzymes that inactivate the antibiotic. For example, bacteria can produce penicillinases, which break down penicillin.

A rigid layer found in bacterial cell walls, primarily composed of sugars and amino acids. It provides structural support and maintains the shape of the cell.

A complex molecule found in the outer membrane of Gram-negative bacteria, also known as endotoxin. It plays a role in the bacteria's structure and can trigger immune responses.

Two distinct types of bacteria categorized by their cell wall structure. Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

A negatively-charged polymer found in the cell walls of Gram-positive bacteria. It plays a role in structural integrity and can act as an antigen.

A protective barrier found outside the peptidoglycan layer in Gram-negative bacteria. It contains lipopolysaccharide (LPS) and other components.

The bacterial cell wall plays a vital role in maintaining the cell's shape, protecting it from osmotic pressure, differentiating Gram-positive and Gram-negative bacteria, and providing surface antigens.

Bacteria that lack a cell wall, making them resistant to antibiotics that target cell wall synthesis and unable to be stained by Gram stain. They are polymorphic and can be difficult to treat.