CYSTIC FRIBROSIS

Chlamydia trachomatis conjunctivitis in a newborn (ophthalmia neonatorum) Conjunctivitis is usually bilateral and occurs during the second week after delivery. Infection occurs from contamination of the eyes on passage through an infected endocervical canal. Chlamydia trachomatis pneumonia also commonly occurs at the same time.

A sample of notes from Medical Virology // I keep the margins empty so that I have space to add in relevant additional material from extra reading

Antimicrobial Agents - Inhibition of DNA and Protein Synthesis

Bacterial chromosome replication

DNA replication

Bacterial Topoisomerases 

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 

Inhibition of Bacterial Protein Synthesis 

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 

Aminoglycosides

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 

Archaea

Archaeans are single-celled and join bacteria to make up the Prokaryotes.  The Archaea classification is a very recent discovery, due to the similarities in appearance and behaviour to bacteria they weren’t separated until the late 1970′s. They mostly live in extreme environments and can be sub grouped: 

Methanogens - produce methane gas as a waste product of their “digestion,” or process of making energy.

Halophiles - live in salty environments.

Thermophiles - live at extremely hot temperatures.

Psychrophiles — those that live at unusually cold temperatures.

Like bacteria, archaea lack a true nucleus. Both bacteria and archaea usually have one DNA molecule suspended in the cell’s cytoplasm contained within a cell membrane. Most, but not all, have a tough, rigid outer cell wall.

use a variety of substances for energy, including hydrogen gas, carbon dioxide and sulfur. 

many archaea thrive in conditions mimicking those found more than 3.5 billion years ago. [eg oceans that regularly reached boiling point — an extreme condition not unlike the hydrothermal vents and sulfuric waters where archaea are found today]

Cysteine Growth Requirements

MICROBIOLOGY MNEMONIC

BoyFriend Lost Penis

B rucella

F rancisella

L egionella

P asteurella

or….

The four sisters “Ella” worship in the “cystein” chapel

Brucella

Francisella

Legionella

Pasteurella

Infectious bacterial diseases and where to find them

[17 Dec 2017] (i thought i’d posted but it’s not appearing? ):) so sorry for the lack of original posts all these months! school has been so tough & i’ve just completed my mid-sem assessments & it’s finally my break! can’t wait to unwind and catch up on my sleep ;-;

Which Microbe Would You Be?

Buzzfeed has a quiz on what bacteria would you be, based on your personality.

I was a Salinicola salarius. (Which isn’t on my Periodic Table of Microbes!)

https://www.buzzfeed.com/grandon/which-bacteria-are-you-based-on-your-personality-3dk99?utm_term=.am4B9qO8B#.ab5oX2B0o

Follow on Twitter @warholScience

Tumblr room🌹

This one’s about bugs

Guys, I love ID. I really hope I get to do an ID rotation on Medicine. If you remember, I once posted the mnemonic I swear by for viruses. Well here is the bacteria counterpart. Also your micro mantra should be: sketchy is life. Love Andrew like I do (this part’s not the mantra, I just love Andrew).

Let me know if you have any questions or need clarification. This is a perfect example of a “not aesthetically pleasing tumblr study post” because sometimes your handwriting sucks and you aint got that kinda time in my life for pretty arrows and banners and I just wanna finish this shit so I can leave the library when will Step 1 even be over why is this my liiiiiife