web analytics

Bacterial Infection Lungs

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 – 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.

Pneumonia causes types symptoms

Alright, so check out this guy, he's gotsome nice looking lungs here, and he's a pretty normal human so every time he breathes,he pulls in some oxygen. That oxygen zooms down this big airway, called the trachea,and then splits down one of the these two branches, called bronchi, then splits somemore into the bronchioles, until it finally ends up in these little sacs called alveoli,which sorta look like little clumps of grapes, and these guys are nestled right up againstsome tiny tiny blood vessels, and at this point the oxygen's like seeya later, anddiffuses right into the bloodstream. Now obviously oxygen's not the only thing you're breathingin though, is ité you're constantly breathing

in A TON of other stuff, especially, whetheryou like it or not, things like microorganisms. You're usually pretty good at making surethese guys don't stick around though and you use techniques as simple as coughing toget rid of them, or you let your immune system do the dirty work. If a particularly nastyorganism makes it in, or your defenses aren't very good, they can start to multiply andinfect your lungs. When an organism has successfully made your lungs their new home, like yourbronchioles or alveoli, you've developed something called pneumonia, which is thisinfection of your lungs. When these guys really get to multiplying, your immune system respondsby sending troops to help fight em off righté

so things like white blood cells. These aregreat and all, because they're trying to help, but what ends up happening is they causeinflammation in these areas where the organisms have set up camp, so they fill with whiteblood cells AND other things, like proteins, fluid, and even red blood cells. These obviouslytake up valuable space in your airways, righté So now this alveoli might be inflammed andfilled with fluid, so when you breath in some oxygen and it gets to these infected and inflammedairways, it's gonna have a way harder time diffusing into the blood stream. So becauseyou aren't getting that oxygen into your blood as easily, one common symptom is thislike shortness of breath and this difficulty

breathing, which is also called dyspnea. Also,like I mentioned, we cough to try and get things out of our lungs, so what do you thinkhappens when we've got all this fluid and other things built upé Well we're gonnatry to cough it up and make some room for oxygen, so another big symptom is coughing.Also, sometimes patients experience chest pains, why might that beé Well there are definitelysome pain receptors near these airways and alveoli, so when they get inflamed, we cantotally feel that! And finally, since your immune system's working to fight againstsome microbe, it's also common to get a fever. Ok Ok, so notice that I've been prettygeneral about the culprit, this mysterious

microorganism, why so vagueé Well, becausethere isn't just one kind of microbe that causes pnemonia, it can actually be causedby all sorts of microbes. The most common ones though are bacteria and viruses, butit can also extend to fungi as well and something called mycoplasma. Between viruses and Bacteria,though, bacteria wins out and is the most common cause of pneumonia in adults, especiallyone called streptococcus pneumoniaie, also sometimes known as pneumococcus, but justremember, it doesn't necessarily have to be caused by this one bacterium, other bacteriathat may cause pnemonia are ones like haemophilus influenzae, legionella pneumophila, and staphylococcusaureus. Aside from bacteria, viruses can also

be a bigtime contributor to pneumonia cases,influenza probably being the most common virus that causes it, but it could also be causedby others. Fungi rarely cause pnemonia because most of our immune systems fight them off.butfor people with weakened immune systems, like with AIDS or cancer, pneumonia from fungican become more of an issue. A common fungal culprit is pneumocystis jiroveci. Finally,these things called mycoplasma can also cause pneumonia in some cases. Mycoplasma are technicallystill bacteria, One important point is that they don't have a cell wall, so common antibioticslike penicillin that work by attacking cell walls, don't work against these guys! Luckilythough, they're the smallest proportion

Leave a Reply