Bacterial chromosome replication
DNA replication
maintain DNA in appropriate state of supercoiling
cut and reseal DNA
DNA gyrase (topoisomerase II) introduces negative supercoils
Topoisomerase IV decatenates circular chromosomes
these are the targets of the quinolone antibacterial agents
Quinolones
bind to bacterial DNA gyrase and topoisomerase IV after DNA strand breakage
prevent resealing of DNA
disrupt DNA replication and repair
bactericidal (kill bacteria)
Fluoroquinolone is particularly useful against
Gram +ves: Staphylococcus aureus, streptococci
Gram -ves: Enterobacteriacea; Pseudomonas aeruginosa
Anaerobes: e.g. Bacteroides fragilis
many applications e.g. UTIs, prostatitis, gastroenteritis, STIs
Adverse effects
Relatively well tolerated
GI upset in ~ 5% of patients
allergic reactions (rash, photosensitivity) in 1 - 2% of patients
Macrolides
in 1952: Erythromycin was isolated as the first macrolide (Streptomyces erythreus)
Newer macrolides: clarithromycin, azithromycin
Structurally they consist of a lactone ring (14- to 16-membered) + two attached deoxy sugars
Mode of action
bind reversibly to bacterial 50S ribosomal subunit
causes growing peptide chain to dissociate from ribosome → inhibiting protein synthesis
bacteriostatic (stops reproduction)
Macrolides’ spectrum of activity
good antistaphylococcal and antistreptococcal activity
treatment of respiratory & soft tissue infections and sensitive intracellular pathogens • e.g. Chlamydia, Legionella
Adverse effects
Generally well tolerated
nausea
vomiting
diarrhoea
rash
large family of antibiotics produced by various species of Streptomyces (“mycin”) and Micromonospora (“micin”)
include: streptomycin, neomycin, kanamycin, gentamicins, tobramycin
Structure = linked ring system composed of aminosugars and an aminosubstituted cyclic polyalcohol
Mode of action of aminoglycosides
Bind irreversibly to 30S ribosomal subunit
disrupt elongation of nascent peptide chain
translational inaccuracy → defective proteins
bactericidal
Spectrum of activity
broad spectrum; mainly aerobic G-ve bacilli (e.g. P. aeruginosa)
used to treat serious nosocomial infections (hospital acquired infections)
First TB antibiotic
Used for cystic fibrosis
Adverse effects
all aminoglycosides have low Therapeutic Index (only a small amount needed to become toxic)
renal damage, ototoxicity, loss of balance, nausea
• Microbiology cheat sheets for the comprehensive final. We were allowed two pages, front and back. I ended up getting a 95%! •
Facultative intracellular
Sulfatides: inhibit PHAGOLYSOSOME FORMATION allowing intracellular survival.
Cord Factor (serpentine growth in vitro): disrupts mithochondrial respiration and oxidative phosphorilation and inhibits leukocyte migration.
Tuberculin + Mycolic Acid: type IV hypersensitivity (delayed hs), Cellular Mediated Immunity (CMI)
Me this week
I thought to write down the “script” to one of my most viewed videos, with 40 study tips & tricks. It’s easier to read them and pass on the word!
Organization Tips:
1. Incorporate homework and classes in you daily planner – that will give you an overall glimpse of how your week will be about and how much time you need to spend in your studying sessions!
2. Color coordinate classes – be it notes, your planner, your textbooks or binders, pick a unique color for each class and work around the hues of that color to get more organized!
3. Make your own syllabus – if your professor doesn’t provide a syllabus for your class, try to make one before the school year working around your given textbooks or other given material.
4. Make study guides – make a study guide from your syllabus and draw before each topic two boxes: one for a midtest and one for the final test. When you have one of these tests, check the boxes when you’ve finished studying the chapter so you won’t miss anything!
5. Reference your material throughout – most of the times, we students work with in-class notes, textbooks and a syllabus. Since we get small bits of information here and there it’s important to reference every page throughout all your material so you can quickly access your information without having to flip endlessly through pages!
6. Keep a dashboard nearby – Whenever you use a notebook or a binder, make a dashboard on the first page with post it notes so you can quickly scribble any questions, homework or page numbers. When you get home, you just need to open your dashboard and attend those notes.
7. Print any tests, exercises and exams you can find – keep those in the end of your binder. These are perfect to practice before exams and tests because they really reflect what you will be tested about. Set an alarm clock for the deadline and start working on those!
8. Condense – organization disappears when you have too many of everything. Working with more than one planner in your life will make everything chaotic. If you think you need a second planner because you don’t have enough space to write in the first one, it’s because you don’t have available time as well. Don’t fool yourself and set achievable goals!
9. Customize your textbooks – most of the times, textbooks are formal books where information is hard to come by. Make your own tabs and write every chapter on them so they stick out – flag any charts, tables or graphics. Everything needs to be incredibly accessible!
10 Print a special planning sheet before finals: Organizing your studying by chapters and/or topics before finals is tremendously important since it lets you organize the amount of time you dedicate to each subject,
Study Sessions and Time Management
11. Save at least one afternoon or one morning a week for intensive studying. These is your “life-saver” – when you get so full of homework and projects that you can’t incorporate them into your daily academic routine, one free afternoon to organize your school life will really come in handy! Make an appointment with yourself!
12. Prepare in advance – although most professors may not ask you to prepare a class in advance, if you have the means to, go ahead. Grab a sheet and make a summary of the chapter your class will be about. Write the major topics and key information and take that guide to class. When your professor repeats previously studied information, you will be able to understand everything much better!
13. Never leave something behind – Even if you have a more light class, where professors don’t request homework or any side projects, don’t let that fool you! Be disciplined and be your own professors! Make your own projects and learn everything you can so you can nail those finals when they arrive.
14. Write your questions – most of the time, in a heavy study session, we come up with tons of questions and sometimes we just leave them behind. Write them down in your dashboard or a small notebook and ask your professors (personally or via e-mail). You can also ask your schoolmates in a facebook group created for that purpose!
15. Set an alarm clock and reward yourself – even if you study during an entire afternoon your studying will be pointless if you don’t take regular breaks. Set an alarm clock for one hour/one hour and a half and then take a 15 minute break. Never study for more than 2 hours straight! Even if you don’t notice, you’ll get less and less focused.
16. . Make a list – before each study session I like to grab my notepad and write down everything that I need to do before my session ends: the chapters I need to read, the pages I need to go through and the homework I need to complete. Sometimes I even write theses lists when I’m in college so I’ll have more determination to complete those tasks once I get home.
17 Work on the least interesting thing first. There are always classes or projects that we like the least – and those are the ones that we need to tackle first. You will start your studying session concentrated, which will let you go through the worst tasks faster.
18 Print, print, print. try to print everything you can and never study from your computer. Having your PDF files printed at hand will let you concentrate better, highlight and write some notes in the margins. You can take these everywhere with you and even turn them into small guides for future classes!
19. If you finish ahead, don’t quit. Perhaps the time you’ve saved for your study session has come to an end way before you have planned. That doesn’t mean you should stop right now – Take that time to review what you’ve learned so far or prepare other classes ahead of time!
20. Study in an organized space – make your own studying corner – bring everything you will need, from textbooks, binders and notebooks, to a cup of coffee and your computer. Keep them neatily organized on your desk so everything is at hand and on sight. Put on some soft background music (links down below) and adjust the lightning.
In class notes
21. If your professor provides PowerPoint slides before each class, print them (six or four per page) and bring them to class. Write in the margins and more throughout information in the back so it’s all condensed and tight. This is where you’ll take your notes. If you prefer to write on lined paper, think about copying some ruled paper to the back of your printed slides.
22. If your professor asks you to prepare your class in advance, try to make a small guide for each class. Open the comments column in MSWord and print the pages with that column. When you go to class, incorporate the in-class notes in that column, next to the relevant information so everything is nice and condensed.
23 If you are in a information-heavy class, try to adopt the Cornell method, which is the best, in my opinion, when you need to be a fast writer. There’s a video right here on how to use this method.
24. If you are in a bits-and-pieces class, which is that kind of class where the professor just gives a few key points and then gives practical examples or makes you work in group, try to adopt the box method – you can draw these boxes yourself or make them with post it notes – these are way more visual and perfect to memorize information.
25. Write in-class flashcards – if you don’t have flashcards around, make tiny flashcards on the top of your notes, where you cover the definitions you’ve written with the name of the definition. Each time you open your notes, try to remember the hidden definition. Automatic studying, every time!
26. Participate in class – nothing better than to be actively involved in your class discussion. For most of us, shy creatures, participating can be dreadful – but once you get out of your box, you’ll see how participating really makes you understand the subject!
27. If you have any questions during class, raise your hand and ask them. If your professor doesn’t like being interrupted, write them down and approach them in the end of the class. Sometimes, the little things we don’t understand are exactly the ones that come up on the final exam!
28. Ask for examples. Examples are probably the thing that makes your brain connect the information faster. If your professor isn’t keen on providing examples, suggest your own and see if your answer comes up right. Sometimes, examples are the thing that really makes us understand our material and our definitions, since they transform formal information into relatable events.
29. Sit at the front. It sounds too straightforward but sitting at the front really makes wonders. You won’t get distracted by what you classmates are doing, you will focus on the professor, who is right in front of you and you will resist the temptation of going to Facebook and Instagram during a boring presentation.
30. Write a brief summary at the end of the class. During those five minutes where everyone is dismissed and leaving the room, write a brief summary of that classes’ key points in the back of a page – this is fundamental in the Cornell method but can be used in any other method as well.
Finals Guide
31 Skim through your material two times: at first, you should start by studying your material starting from the end. The last lessons will be fresh in your memory and it’s very important to reinforce your knowledge on these while you can. In the second reading, you should start from the beginning, as usual. It’s important to make these two readings so you can go through the information in a much more flexible way.
32. Make a mindmap of each chapter. A mindmap is a chart that relates key words and important information, making it easy to understand the relationship and hierarchy between such key words. Use colors and images to memorize your material better. Oh, and don’t forget to check out my video on how to make mindmaps!
33. Read each of the titles and try to say out loud its contents, explaining each concept and the relationship between them. Imagine you are the teacher and are lecturing that subject to a crowd. If you skip any of the subjects, do it all over again. The more you repeat, the better you will memorize.
34. It’s time for some flash cards! Write the topic or the title on one side and the meaning or the explanation on the other. Try to cover as many topics or titles as you can and go through your cards while memorizing as best as you can each of the concepts. Try to do it backwards if you have time to do so!
35. On the day before the exam, skim through your mindmaps and flash cards again and always try to study while talking. Saying your content out loud will force your brain to relate information in a much more cohesive way and you’ll memorize everything much better.
36. Read the entire exam from top to bottom. Underline or circle any important words that you think will be crucial in you answer. After that, calculate how much time you should spend answering each question: this simple calculation will take only twenty seconds and will help you organize your time. Try to save five minutes at the end for revisions.
37. If you are solving a written exam and not multiple choice, try as much as possible to organize each answer in a structured way, saving two lines just to present your line of thought and writing each different argument in a different paragraph. Draft a conclusion at the end to underline the centre of your answer. Sometimes softly underlining some keywords is important to make your professor notice that you’ve correctly given importance to certain concepts.
38. Use these symbols for each question: one dot if you aren’t sure of the answer, two dots if you are sure of your answer and a circle if you are completely unaware of your answer. Start by answering any question with two dots; after those are all answered, go on through the two dots question. Leave the circle questions to the end – and ALWAYS answer them! Even if you don’t know what they’re about, who knows if you will be able to come up with something right?
39. Review your test one final time – many times, we make a lot of mistakes under stress and now is when you should spot them and amend them. This can be the difference between a B and an A!
40. Don’t take this too seriously – school is an important aspect of our lives but it isn’t everything. Failure comes many times and these failures can even drive you away from something that was simply not meant to be. Don’t stress out because everyone goes through the same!
New background! Download higher quality photo here!
https://drive.google.com/file/d/1F5SlJmB8YiNNtGuKrc-QtMnrrjZ1tOHL/view?usp=sharing
Staphylococcus epidermidis is a coagulase negative, Gram-positive coccus. The organism uses sophisticated regulatory networks to adapt its metabolism to suit varying environmental conditions. S. epidermidis relies on biofilm formation to protect cells from the host immune system and other anti-microbial molecules.
Colon: pseudomembranous colitis due to Clostridium difficile (pseudomembranous inflammation) Note the gray-yellow pseudomembrane covering the entire mucosal surface. Damage is due to a toxin produced by C. difficile. Similar to diphtheria, the toxin produces necrosis of the mucosa and submucosa without actual invasion by the bacteria. A toxin assay of stool is the best method for diagnosing the disease. Ampicillin is the MC drug causing pseudomembranous colitis and does so by destroying colonic bacteria that normally keep C. difficile in check.
Acute or Subacute Bacterial Endocarditis is an infection of the heart’s endocardium. The endocardium is the inner lining of the heart muscle, which also covers the heart valves. Bacterial Endocarditis can damage or even destroy your heart valves. The difference between acute and subacute bacterial endocarditis is acute bacterial endocarditis is a sudden onset, whereas subacute bacterial endocarditis is a gradual onset.
Acute endocarditis most often occurs when an aggressive species of skin bacteria, especially a staphylococcus (staph), enters the bloodstream and attacks a normal, undamaged heart valve. Once staph bacteria begin to multiply inside the heart, they may send small clumps of bacteria called septic emboli into the bloodstream to spread the infection to other organs, especially to the kidneys, lungs and brain. Intravenous (IV) drug users are at very high risk of acute endocarditis, because numerous needle punctures give aggressive staph bacteria many opportunities to enter the blood.If untreated, this form of endocarditis can be fatal in less than six weeks.
Subacute endocarditis is caused by one of the viridans group of streptococci (Streptococcus sanguis, mutans, mitis or milleri) that normally live in the mouth and throat. Streptococcus bovis or Streptococcus equinus also can cause subacute endocarditis, typically in patients who have some form of gastrointestinal cancer, usually colon cancer. Subacute endocarditis tends to involve heart valves that already are damaged in some way, and it usually is less likely to cause septic emboli than acute endocarditis. If untreated, subacute bacterial endocarditis can worsen for as long as one year before it is fatal.
Hey guys, since my previous post on Morning Routines was very well received, I decided to make a night version. This small infographic thingy outlines the things I do at night to prep myself for rest, as well as some other things you could try to ensure you get a good night’s sleep. Hope this helps, and don’t hesitate to drop me an ask if you have any questions!
P.S. the typefaces used are Bromello and Montserrat
Amazing web site!