Class Notes (811,169)
Canada (494,539)
Health Sciences (1,234)
HSS1100 (155)
Lecture 5

Lecture 5.docx

13 Pages
Unlock Document

University of Ottawa
Health Sciences
William Yan

-2nd midterm: 30 MC, 10 SA (worth 30 marks) -> 1 or 2 word answers -parasite lecture: study notes (supplement with slides for info not from the study package) -don't need to know most drug strains -may need to know common drugs or resistance -cysts of parasites similar to spore form of bacteria Lecture 5 Slide 1: Gram Positive Bacilli -rod/cylinder shaped bacteria -have some unique characteristics -e.g.: spore forming and non-spore forming rods Spore Forming Rods -very few bacteria can make spores -spores can resist negative environments -e.g.: if environment is becoming unfavourable, bacteria can change from a regular, multiplying form to its dormant spore form, which has a thick wall structure that offers protection -spore form is 'hibernating' -it is not actively growing -when the environment becomes favourable, it will change back into its vegetative form and can start multiplying again -there are 2 genus that belong to this group: bacillus and clostridium -these are known to make very powerful exotoxins which are mainly responsible for the disease symptoms Slide 3: Bacillus 1) Bacillus anthracis -causes the disease anthrax -can be picked up through livestock or soil -is a soil-born pathogen -aerobic organism (requires oxygen for growth) which is the main difference between clostridium which is anaerobic -can make spores which allow it to become resistant to disinfectants, UV light, etc. -the spore form is difficult to remove from the environment -spores can be inhaled, ingested, through a wound, etc. -potential agent for bio-terrorism -most of the virulence factors are carried on plasmid DNA (2 plasmids are involved) -bacteria has 1 chromosome with genetic information that allows it to multiply -some bacteria carry small pieces of independent DNA called plasmids that can self- replicate and can carry genes for things like anti-biotic resistance, toxins, etc. and the bacteria don't need these to survive but can produce advantages -pXO1 plasmid and pXO2 plasmid -pXO1 responsible for edema factor, protective antigen, and lethal factor -these need to come together in order to be lethal; if any factor is missing, the bacteria is not pathogenic / lethal -pXO2 produces a capsule that protects the bacterium against host defense mechanisms and allows it to survive in the body; this is required for pXO1 to be lethal -in order for Bacillus anthracis to be lethal all 3 factors and the capsule must be present (i.e.: both plasmids) -penicillin and other anti-biotics are effective in treating patients -treatment should be rapid for effectiveness -vaccine is available against the PA (protective antigen) protein -spores take cutaneous and respiratory routes (through animals or soil) Slide 7: 2) Bacillus cereus -spore forming -found in soil -infectino comes from comsuming contaminated food -e.g.: rice products (rice is grown in wet, soil environments which allow for spore growth); once rice dries, it is unfavourable for growth but its spore form allows it to remain dormant up until it is rehydrated and the spore is germinated and the bacteria can start multiplying -during the cooking stage, the bacteria can turn into the spore again and survive in the heat -the enterotoxin (toxin that affects the gut; special form of exotoxin) is responsible for illness -enterotoxin can only be produced when it is actively multiplying (vegetative form) -e.g.: when the rice is wet or after you cook it and let it sit around -usually get infected when you eat leftover rice (at room temperature, before refrigeration), where the bacteria has a chance to start multiplying again and make the enterotoxin -it is important to reheat or recook leftover rice -2 types of enterotoxin are produced: 1) heat labile toxin -cannot survive cooking -not that serious; causes diarrhea, nausea, abdominal pain -usually overcome within a day 2) heat stable toxin -survives in heat -more serious symptoms -usually overcome within a couple days -anti-biotic treatment is useless since it is the toxin in the rice that causes the disease; not the actual bacteria itself Slide 8: Clostridium -the main difference between this and bacillus is that clostridium is anaerobic and bacillus is aerobic -because it is anaerobic, it is important that it is spore forming -normally, anaerobic bacteria are killed in the presence of oxygen -in its spore form, it can survive in oxygen and cause problems because it can remain dormant until it gets back into an anaerobic environment Slide 9: 4) Clostridium botulinum -the most dangerous and rapidly fatal foodborne illnesses known -produces a powerful neurotoxin that affects the CNS -the neurotoxin blocks the release of Ach (required for stimulating nerve endings) and inhibits contraction; muscles become relaxed and paralysis occurs (one of the most common symptoms) and will end up affecting breathing -symptoms: muscle paralysis, double vision, trouble swallowing, muscle weakness, respiratory failure, etc. -fatality depends on the amount of toxin you are exposed to -rapid treatment and diagnosis is important -10 cases a year in Canada; mostly non-fatal -the most common source of food for botulism are canned products -most cases are from home-canned products -once a spore enters a can (due to poor cooking or washing), it can thrive in the anaerobic environment in the can -a picogram of botulinum toxin is enough to be deadly -spores are very heat resistant, but the toxin that it produces in this case is not heat resistant -even though a can may contain the toxin, if the content is heated, the neurotoxin is inactivated because the botulinum toxin is very heat sensitive -we may have consumed botulinum spores, but with the inactivated toxin -smoked fish can also cause botulism -smoking creates an anaerobic environment that may allow some bacteria to grow -smoked fish aren't always cooked fully -most botulism cases comes from the native population -certain marine strains of C.botulinim exist and colonize in whales, seals, etc. in their gut or muscles; the natives often just smoke it, dry it, or consume it raw -because the natives live in such isolated locations, there is a delay in treatment and symptoms reach an irreversible stage Infant Botulism -most of the time, ingesting spores will not lead to serious outcomes -because infants lack a normal flora and do not have a strong immune system, in some cases, infants can develop symptoms of botulism because they have ingested spores -if spores enter the gut and finds an anaerobic environment with no competing normal flora, it can produce some toxin which is enough to cause symptoms -often, honey can contain botulinum spores -if the child is diagnosed early enough, the outcome is positive -this is due to the minimal amount of toxin -not recommneded to give honey to infants -another group that is at risk of botulism symptoms from ingesting spores are adults with Chron's disease or other bowel diseases that may influence gut flora Uses of the Botulinum Toxin -botox = type A -small amounts of botox used to treat some medical issues -e.g.: cosmetic surgery -used to relax muscle, treat muscle twitching / spasms, excessive sweating, chronic pain, jaw tension, migraine headaches, eye muscle disorders (i.e.: blepharospasm and strabismus) etc. Slide 10: 5) Clostridium tetani -causes tetanus -it can make a neurotoxin (tetanus neurotoxin) -the tetanus spore is found in soil environments -anything contaminated with soil and the spores may infect wounds -a slightly anaerobic environment is created when there is a cut (lack of bloodflow) -the exotoxin is known as tetanospasmin -opposite effect from the botulinum toxin -tetanospasmin prevents the muscle from relaxing -symptoms include muscle spasms, lock jaw, respiratory issues, mobility issues -there is an efficient vaccine for tetanus -it is effective but does not offer lifetime protection -requires a booster shot every 10 years due to a gradual decrease in effectiveness -because the booster shot is so infrequent, hospitals will give you a tetanus shot when you come in with a major wound Slide 15: 5) Clostridium perfringens -aerobic -spore forming -produces a toxin that destroys cells (rather than a neurotoxin) -known as gas gangrene -it is important to diagnose and treat as soon as possible -treated with antibiotics or flushing the area with pure oxygen which will kill or revert the bacteria back into the spore form so that it no longer can produce the toxin -gangrene common during trench warfare Slide 16: 6) Clostridium difficile -potentially classified as an opportunistic pathogen -affects mostly elderly patients that are undergoing long term anti-biotic therapy -anti-biotic associated pseudomembranous colitis -in elderly patients (undergoing long term antibioitic treatment), their gut flora is almost depleted and their immune systems are not fully active (due to pre-existing conditions) and there is no longer competition for C.difficile which can multiply much more rapidly -produces 2 toxins: 1) toxin A -causes diarrhea 2) toxin B -most dangerous toxin -cytotoxic toxin (can destroy the lining of the gut) -treatment involves discontinuing antibiotic treatment, using other antibiotics that don't affect gut flora as much, etc. Slide 19: Non-Spore Forming Rods -regular gram positive bacilli -most bacteria don't form spores 1) Listeria monocytogenes -causes listeriosis -is a psychrophile -multiplies in low temperature (i.e.: refrigerator) -listeria commonly found in animals, soil, the environment, etc. -meat processing plants are usually contaminated with listeria -this is not a problem as long as you cook the meat and keep it refrigerated so that the bacteria cannot multiply into a large enough number for it to be dangerous -meat products usually contain a small number of listeria; because listeria can multiply at low temperatures, it will m
More Less

Related notes for HSS1100

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.