Bacterialvaginosis is a disease that's caused by the overgrowth of a type of bacteria that's called Gardnerella vaginalis, Gardnerella vaginalis. And as the name might suggest, this is the most common vaginal infection. Now I wanna put these really big quotes
around the term infection because the thing that's interesting about Gardnerella vaginalis is that it's a bacteriathat's naturally found in the vagina. Now some may consider this to be a sexually transmitted infection, which is interestingbecause it doesn't cause
any problems until there'stoo much of it there. So when we look to the causes of bacterial vaginosis, they are all things that change the vaginal environment. That can include acts like douching, so douching, or rinsing of the vagina. The other is having newor multiple sex partners.
And finally, another known cause is the use of antibiotics. This could be in the case of somebody that has a throat infection or a pneumonia that's on antibiotics which will then attackthe bacteria that exists within the vagina andallow Gardnerella vaginalis to overgrow and cause bacterial vaginosis.
So we've touched a little bit on it here, but I wanna draw it out. So when we talk about the pathophysiology of a disease, we'retalking about the mechanism by which that disease occurs. So in order to understandthe pathophysiology of bacterial vaginosis, we need to take a look at a sample of bacteria
that exists in the vagina. So I'll draw out someGardnerella vaginalis bacteria, and so I'll put this up in our key. This is the symbol forGardnerella vaginalis. And I'll draw a few of them around here, but I also wanna show that there are a lot of other bacteriathat exist in this sample. So if you really look at it here,
The Immune System Explained I Bacteria Infection
Narrator: Every second of your life youare under attack. Billions of bacteria, viruses, and fungi are trying to make youtheir home. So our bodies have developed a super complex little army with guards,soldiers, intelligence, weapons factories and communicators to protect you from uh,well, dying. For this tutorial, let's assume the immune system has twelve different jobs. For example, kill enemies, communicate etc. And it has 21 different cells and twoprotein forces. These cells have up to four different jobs. Let's assign them. Here are the interactions. Now let's make this understandable. First of all, let's addcolors to the jobs. Now let's illustrate
the cells. The central color represents the main job of the cell, while the surrounding ones represent secondary duties. Now the immune system looks like this. Now the interactions. Isn't this complexity just awesomeé For this tutorial we will only talk about these cells and ignore the rest. So what happens in the case of an infectioné Music It's a beautiful day when suddenly a wild rusty nail appears and you cut yourself. The first barrier of the immune system isbreached: your skin. Nearby bacteria sieze
on the opportunity and enter your wound.They start using up the body's resources and double their numbers about every 20 minutes. At first they fly under the radar but when a certain bacteria population isreached, they change their behavior and start to damage the body by changing the environment around them. The immune system has to stop them as fast as possible. First of all your guard cells, known as macrophages, intervene. They are huge cells that guard every border region of the body. Most of the time they alone cansuffocate an attack because they can devour up to 100 intruders each. They swallow the intruder whole and trap it inside a membrane.
Then the enemy gets broken down by enzymesand is killed. On top of that, they cause inflammation by ordering the blood vesselsto release water into the battlefield so fighting becomes easier. You notice this as a very mild swelling. When the macrophages fight for too long, they call in heavy backup by releasing messenger proteins that communicate location and urgency. Neutrophiles leave their patrol routes in the blood and move to the battlefield. TheNeutrophiles fight so furiously that they kill healthy cells in the process. On top of that, they generate barriers that trap and kill the bacteria. They are indeed so deadly that they evolved to commit suicide
after five days to prevent them from causing too much damage. If this is not enough to stop the invasion, the brain of the immune system kicks in. The dendritic cell gets active. It reacts to the signals of the soldiers and starts collecting samples from the enemies. They rip them into piecesand present the parts on their outer layer. Now, the dendritic cell makes a crucial decision. Should they call for antivirus forces that eradicate infected body cells,or an army of bacteria killersé In this case, antibacteria forces are necessary.It then travels to the closest lymph node in about a day. Here billions of helper andKillerT cells are waiting to be activated.
When TCells are born they go through adifficult and complicated training process and only a quarter survives. The survivingcells are equipped with a specific setup. And the dendritic cell is on its way lookingfor a helper Tcell with a set up that's just right. It's looking for a helper Tcellthat combines the parts of the intruders which the dendritic cell has presented on its membrane. When it finally finds one, a chain reaction takes place. The helper Tcell is activated. It quickly duplicates thousands of times. Some become memory Tcells that stay in the lymph node and will make you practically immune to this enemy.Some travel to the field of battle to help
Tuberculosis TB Progression of the Disease Latent and Active Infections
Tuberculosis, or TB, is one of the oldestand most common infectious diseases. About one third of the world population is believedto be infected with TB. Fortunately, only about 5% of these infections progress to activedisease. The other 95% of infected people are said to have a dormant or latent infection;they do not develop any symptoms, and do not transmit the disease.Tuberculosis is caused by a rodshaped bacterium, or a bacillus, called Mycobacterium tuberculosis.An infection is initiated following inhalation of mycobacteria present in aerosol dropletsdischarged into the atmosphere by a person with an active infection. The transmissionprocess is very efficient as these droplets
can persist in the atmosphere for severalhours and the infectious dose is very low â€“ less than 10 bacilli are needed to startthe infection. Once in the lung, the bacteria meet with thebody's firstline defense the alveolar macrophages. The bacteria are ingested bythe macrophages but manage to survive inside. Internalization of the bacilli triggers aninflammatory response that brings other defensive cells to the area. Together, these cells forma mass of tissue, called a granuloma, characteristic of the disease.In its early stage, the granuloma has a core of infected macrophages enclosed by othercells of the immune system. As cellular immunity
develops, macrophages loaded with bacteriaare killed, resulting in the formation of the caseous center of the granuloma. The bacteriabecome dormant but may remain alive for decades. This enclosed infection is referred to aslatent tuberculosis and may persist throughout a person's life without causing any symptoms.The strength of the body's immune response determines whether an infection is arrestedhere or progresses to the next stage. In healthy people, the infection may be stopped permanentlyat this point. The granulomas subsequently heal, leaving small calcified lesions. Onthe other hand, if the immune system is compromised by immunosuppressive drugs, HIV infections,malnutrition, aging, or other factors, the
bacteria can be reactivated, replicate, escapefrom the granuloma and spread to other parts of the lungs causing active pulmonary tuberculosis.This reactivation may occur months or even years after the initial infection.In some cases, the bacteria may also spread to other organs of the body via the lymphaticsystem or the bloodstream. This widespread form of TB disease, called disseminated TBor miliary TB, occurs most commonly in the very young, the very old and those with HIVinfections. Tuberculosis is generally treatable with antibiotics.Several antibiotics are usually prescribed for many months due to the slow growth rateof the bacteria. It's very important that
the patients complete the course of the treatmentto prevent development of drugresistant bacteria and reoccurrence of the disease.