History of Antibiotic Discovery

The ability of bacteria to survive and multiply in the presence of antibiotics.

Changes in DNA of bacteria that alter their ability to be killed by antibiotics altering the target site.

Bacteria can break down antibiotics outside the cell, rendering them inactive.

Bacteria modify antibiotics so that they can't bind to or affect their target.

Bacteria actively pump antibiotics out of the cell, preventing them from working.

Bacteria change the structure of proteins or other molecules that antibiotics are designed to bind to so antibiotic can't affect the target.

Mutations in PBPs prevent antibiotics like methicillin from binding and affecting bacterial cell wall synthesis.

An enzyme produced by some bacteria that breaks down penicillin-like antibiotics.

Methods bacteria use to survive antibiotic treatments. These include inactivation of the antibiotic, reduced uptake, or active removal.

Small, circular DNA molecule separate from a cell's main chromosome. Often carries genes not essential for survival.

Antibiotic resistance genes spread quickly between bacteria via plasmids and other mechanisms.

The selection of multiple antibiotic resistance genes on the same plasmid.

Plasmids carrying antibiotic resistance genes persist even without antibiotic pressure, implying potential benefits beyond just resistance.

Antibiotic-resistant cells that survive in a host even after treatment.

A non-essential genetic element that can replicate independently or integrate into a chromosome.

Plasmids are DNA molecules that replicate independently from the host chromosome and prioritize their own replication.

Viruses that infect bacteria; they are essential components of microbiomes.

A viral replication cycle where the virus replicates and immediately lyses (breaks open) the host cell.

A viral replication cycle where the virus integrates its DNA into the host's DNA, becoming dormant.

The collection of all viruses (bacteriophages) present in a microbiome.

Viral and bacterial diversity are related, such that shifts in one affect the other.

Cells with plasmids often have a survival advantage due to multiple copies of the genes they carry.

Viral genomes can be either double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA.

A state where a bacteriophage's DNA integrates (as a prophage) into the host bacterium's genome without immediate destruction.

Bacteriophage DNA integrated into the host's bacterial genome.

A bacterial immune system utilizing an array of DNA sequences (spacers) to target and destroy invading viral DNA, like a bacterial immune defence.

Constant evolutionary struggle between bacteriophages and their bacterial hosts. Bacteria evolve defence mechanisms like CRISPR against viruses, while phages evolve ways to overcome these defenses.

Maintenance of phage DNA as an episomal plasmid within the host genome rather than integration.

Transfer of genetic material between unrelated species, sometimes through bacteriophages.

Bacterial defence mechanisms that recognize and cleave foreign DNA (like phage DNA), protecting the bacterial genome.

Bacteriophages can affect colonization resistance, either helping or hindering it. Pro-phages (lysogenic) can become active (lytic) during stress from pathogens, infecting other bacteria (lytic or lysogenic). This limits fast-growing bacteria, which could be either beneficial or harmful.

Microbiomes, with a functioning phage network, recover quickly after disturbances like antibiotic treatment or a shift in bacteria types (dysbiosis). New phage-bacteria interactions form, and this recovery might include the transfer of beneficial genes between bacteria.

Changes in the microbial community (dysbiosis) also affect the phage-bacteria interactions. New relationships between phages and bacteria are formed, leading a new steady state

Prophages (dormant viral forms) can become active (lytic) viruses in response to stress from pathogens, leading them to infect other bacteria.

Phages may move beneficial genes from one bacteria to another, contributing to microbiome resilience after dysbiosis (microbial imbalance).

The process of finding and developing new antibiotics, starting with penicillin and then expanding to many other types.

PBPs are bacterial proteins that help build the cell wall. Mutations in these proteins can make bacteria resistant to antibiotics like methicillin.

An enzyme produced by bacteria that breaks down penicillin-like antibiotics, making them ineffective.

A protein in bacterial cell membranes that pumps antibiotics out of the cell, preventing them from reaching their targets.

Bacteria that are not susceptible to the antibiotic and survive the treatment.

Bacteria that were initially present at low levels, but can thrive after antibiotic treatment since their competitors are gone.

New bacterial species that arrive and colonize the space left vacant by antibiotic treatment.

Genes that allow bacteria to survive and multiply in the presence of antibiotics.

Plasmids can be transferred between bacteria, spreading antibiotic resistance genes even between different species.

Plasmids carrying antibiotic resistance genes persist even without antibiotic pressure. This suggests they may provide benefits beyond just resistance.

The ability of the phage community (phageome) to adapt and recover after disruptions, such as antibiotic treatment, leading to a new stable state for the microbiome.

The CRISPR-spacer region in bacteria stores a record of past phage infections, acting like a bacterial immune memory.

Host mutations that prevent phage adsorption or injection (receptor changes, etc.), CRISPR/Cas9, and superinfection.

Phages adapt/mutate to overcome host resistance or adapt to new hosts or encode anti-CRISPR proteins (ACRs).

Plasmids are small, circular DNA molecules that replicate independently within bacteria. Their main goal is to replicate themselves, even if this means potentially harming the host cell.

Bacteria carrying plasmids often have a survival advantage because they have multiple copies of the genes on the plasmid, which can provide beneficial traits, such as antibiotic resistance.

The phageome is the collection of all the bacteriophages (viruses that infect bacteria) within a microbiome. It's like the viral community in a particular environment.

The lytic cycle is a rapid viral replication cycle where the virus destroys the host cell. The lysogenic cycle, however, involves the viral DNA integrating into the host's DNA, becoming dormant and replicating along with the host.

Bacteriophages play a crucial role in shaping the diversity of microbial communities by infecting and killing certain bacteria, thus influencing the overall composition of the microbiome.