Lecture 12

Question 1

Antibiotic prescribing leads to development of resistance

Answer 1

Staph A. become resistant to Penicilin over decade ish
I year of Methicilin Stap A become resistant
-bacterial evolution is rapid
-darwinians selection due to antibiotic resistance
-Antibiotics starting to become less effective. People with infections can die, as antibiotics are now resistant and hard to treat. Bacteria winning. Needing to change healthcare methods.
-Blood for prostate increases PSA. Gun into rectum and into prostate. High risk of infection due to high bacteria in rectum, being injected in potentially sterile prostate. Currently given antibiotics to avoid infection. procedure may have to change because of risk of infection, and risk of infection that cannot be treated easily
-Prescription vs consumption.
-fluctuation in daily consumption. France using lots of antibiotics (2x swiss/dutch). French given antibiotics for conditions where antibiotics arent effective (e.g. virus). Therefore risk for having antibiotics is infinitely higher (1/500 risk of people being directly admitted to hospital due to significantly harm due to antibiotics) risk increases as harm more common, rash, diarohea (1/4 risk).
Adverse effects of antibiotics is common/well know and dwarf any potential benefits.
-limit antibiotics use: 1) by not prescribing them when theyre not needed. 2) do research to show that the antibiotics used are working very effectively at right does 3) and see if can treat with antibiotics in a shorter time period effectively (e.g. 4 weeks instead of 6 weeks)-limits amount of use
Highest oversconsuming countries: 1.France. 2.Greece
-seasonal fluctuations greater in winter. (pneumonia is more common) increased prescription for colds and flu’s
NZ: upper worse than spain. poor internationally

Question 2

Correlation between penicillin use and prevalence of penicillin non-susceptible S. Pneumonia.

Answer 2

5 of step Pneumonia (primary cause of pneumonia) vs resistant/less effective
France: high prescription of antibiotics:high resistance
Netherlands: low prescription: low resistance
Correlation between consumption and resistance between any bacteria is tight/high
-same for all bacteria
-Suprafloxis and Ghonorrhea. Now resistant

Question 3

What are one of the best methods of preventing colds and flus?

Answer 3

Preventing transmission: washing hands
Hand hygiene as healthcare workers to prevent infections spreading from person to person in the hospital
-Doctors must be maticulus (5x manditory times)
Good general person hygiene to prevent infection spreading. e.g. cough/colds
-moderated in community

Question 4

Transmission of Infectious Disease- Direct

Answer 4

Dependant somewhat, on pathogen’s target
Direct: (Spouses (people sharing the same bed) and children are at highest risk)
1. contact
2. sexual transmission
3. faecal- oral (Hepatittus A, someone who has prepared food but not washed hands sufficiently) -Polio
4. droplet (coughing and sneezing TB)
5. airborne (coughing and sneezing TB)

Question 5

Transmission of Infectious Disease- INdirect

Answer 5

Dependant somewhat on pathogen’s target
Indirect Transmission: (when an infectious disease is spread from one person to another person, not at the same place, not at the same time) e.g. TB.
1. contact
2.vector borne (mosquito. healthcare workers)
3. healthcare worker
4. transfusion and iatrogenic (blood transfusion , risk to recipient)
5. airborne (TB)

Question 6

SARS Explosive Transmission

Answer 6

Severe Acute Respiratory Syndrome
-killing many healthcare workers
-Hong Kong airport, shut down during SARS
- lots of productivity money lots
-Index case of SARS: infection on person and then rapid fire spreading. some people were particularly good at spreading.- easy to do this measurement as no one had this illness before. could just test blood to see/diagnose.
Cannot do this for Influenza A/Rhino virus (colds). everyone has had it. would show on blood test, to have antibodies against influenza A, B and other cold viruses (hard to see who infected who)
-explosive transmission of infectious disease happens every winter/autumn/spring with colds and flus

Question 7

Infection control and Prevention (think of an example for each): 6x Universal Precautions

Answer 7

Universal precautions:

• must do always to protect ourselves and patients
  1. gloves/gowns for handling potentially contaminated substance (body fluids) - ebola suits
  2. decontamination of spills (e.g. vomit)
  3. Disposal of sharps/needles (if placed in bin cleaners/nurses at risk of accidental contamination/infection of Hep B/HIV)
  4. waste management
  5. environmental cleaning (bed and surroundings. Terminal cleaning/disinfection important before place another sick person in that station)
  6. Hand hygiene

Question 8

Importance of Infection control and prevention

Answer 8

antibiotics losing important so more important

Critical first step to recognise those who are carrying infections. and their risks

Question 9

Infection control and Prevention (think of an example for each): Contact precautions

Answer 9

Universal Precautions + extra contact precautions

• infection with multi-resistant organisms which antibiotics cannot influence (including diarohhea)
  1. gloves for all patient contact
  2. gowns/eyewear if risk of contamination

Question 10

Infection control and Prevention (think of an example for each): Droplet precautions

Answer 10

• infection with multi-resistant organisms which antibiotics cannot influence (including diarohhea)
  1. mask for close contact
• niceria meningititis lives in back of throat and nose, cause bacterial meningitis. when first admitted everyone wears masks

Question 11

Infection control and Prevention (think of an example for each): Airborne precautions

Answer 11

-infection with multi-resistant organisms which antibiotics cannot influence (including diarohhea)
1. respiratory mask for patient and staff
(TB)

Question 12

Classification of viruses: Structural

Answer 12

Structural classification - scientific classification - less useful/used

1. Nucleic acid (DNa or RNA), +sense (genome/nucleic acid is in correct direction to encode) or -sense (genome/nucleic acid is backwards, and needs to make a positive sense copy before it can encode), strands, segments
2. Capsid Shape (virus protein shell that encases the protein acid. Always made of viral proteins) (icosahedral, helical..)
3. Envelope?
   - Hepatitis B is an enveloped partially double stranded DNA virus
   - HIV is an enveloped +ve sensed RNA retrovirus (retrovirus meaning that it needs to make a DNA copy first (even though +ve sensed), DNA gets stuck in host nucleus, and host nucleus gets tricked into making viral proteins)
   - Measles is a +ve sensed RNA virus (essentially piece of RNA that can go and make proteins)
   - Not a useful classification. But important for some (e.g. HIV- so that the drugs we use for HIV, can help to work out how HIV might work)

Question 13

Classification of viruses: Disease

Answer 13

Disease Classification: -doesnt nescessarily include same/similar viruses (not all encompassing. is user friendly)
Hepatitis
HAV- picornovirus (RNA)
HBV - hepadnavirus (DNA)
HCV- flavivirus (RNA) - similar to yellow fever and zika virus
-all in different families/non related. Are completely different but grouped together by doctors, as they effect liver cells “hepatocytes” and damage liver cells primarily
-hep. D, E and F as well
Epstein-Barr virus is not considered a hepatitis virus. is a human herpies virus. can cause Hepatitus. but main syndrome is Glandular Fever- as in come people this results in a swollen liver. if blood test is taken will see that liver is inflamed
Respiratory viruses: a large group of unrelated viruses
-e.g. RSV, influenza, coronavirus
-all however get up throat and nose and give similar (runny nose) symptoms

Question 14

Classification of viruses: Transmission

Answer 14

Transmission
1. Arbovirus: “ARthropod BOrne” (insect borne) virus - Zika virus, Dangi virus - mosquito/sand-fly
2. Enterovirus: faecal-oral - polio: but doesnt cuase diarohea, causes damage to peripheral nerve roots
3. Respiratory virus: droplets/contact
(can fit into 2x classification groups. infection they cause or transmission manner)

Question 15

Classification of viruses: Human Herpes Viruses

Answer 15

classified into their own group
"human herpes virus" are related viruses
-same properties throughout the group
-some Oncogenic
-all have latency (get, get infected, get over infection, but never fully get rid of virus in your body) - everyone has brain virus/human herpes 6 virus. Caught as infant, causes illness in infants. Has a number of pseudonims - slapcheek disease  (high fever, red cheeks, but otherwise fine) but virus remains living/viable in the brain

Question 16

Virus Infection

Answer 16

Virus must interact with something on the host cell- give virus their tropism (Target cell) (HIV has glycoprotein 120 trimeric protein on outside which binds directly to a CD4 receptor on outside of WBC (helper T) killing these cells during replication etc. when conc of Helper T cells gets really low, can get AIDS)
1. Virus attachment and entry
2. Host cell enzymes degrade the capsid and Nucleic acid released (HIV contains Reverse transcriptase, polymersase enzyme which make DNA from RNA)
3. m(positive sense)RNA formed (viral polymerase. Made DNA from RNA, encorporated in nucleus, transcription factors activated, nucleus transcribes virus/HIV messenger RNA) (in some instances the DNA can go and directly make protein)
4. Protein synthesis (translation) (sometimes made in cytoplasm inefficiently. But usually efficiently in endoplasmic reticulum by ribosomes) - main thing that viruses lack (ability to synthesize proteins)
5. Genome replication (lots of virus proteins required to make capsids)
6. Assembly- usually under cytoplasms
7. Release (a) by Budding off and not damaging cells. (b) explode, damage cells, viruses go everywhere
-most viruses result in illness. Symptoms due to damage to cells and/or Immune system activation
-Hep B doesnt destory liver cells, buds off. But liver cells with Hep B inside put up white flag, and cytotoxic C cells come and attack the liver cells. doesnt matter if only 1-2 liver cells, if large proportion then liver becomes inflamed. Tender swollen liver, fever, off food, fatigued etc. Is the immune system which is both damaging liver, and causing widespread systemic symptoms
Influenza does both (damages cells in nose causing you to sneeze + immune cell trying to kill cells infected with influenza)

Question 17

Viral Tropism

Answer 17

HIV glycoprotein 120 = Helper T cell Cd4 molecule
Infleunza virus haemagluttinin = sialic acid on epithelial cells- important for cell-to-cell signalling. Certain sialic acids in throat, airways, nose (what Influenza hones for), which differ from those in gut/deep down in alveolar in lungs (doesnt interact with helper T cells. only when T cells has understood influenza virus.) (but mostly cytotoxic cells and B cells)
Hepatitis B surface antigen = unknown receptor on hepatocyte

Question 18

Rotavirus

Answer 18

a reovirus
non-enveloped ds (doesnt bud off. caueses cell to swell and release soccerball like viruses everywhere) + RNA virus
with icosahedral capsid of 3 concentric protein shells
VP4 viral protein spikes on outer shell on outer shell/made the protein capsid (VP7)
(VP4 and VP7 enable it to ) attach to integrins or sialic acid on colonic epithelium
-What kind of illness will rotovirus cause?: Targets epithelial cells in gut, particularily colon –> Diarohea. LEading cuase of pedeatric diarohea (diarohea in young children) can be a major cuase of death. now have effective vaccine. Develop immunity over years- Adults seldom get sick from rotovius

Question 19

Diagnosis of viral iillness

Answer 19

Clinical- Cold:fatigue, runny nose, sneezing frequently, slight cough, short term sore throat. mostly straight forward. doesnt say which virus it is - just thee for reasurrance, and to see if the time period of illness can be decreased. (can disrupt skin, rashes, some are so characteristic e.g. chickenpox, measles(not always 100%), herpes)
Visualisation (seldom useful for submicroscopic entities). No. Meni virus is only one which can be seen under microscope- only one big enough 
Viral culture (requires a culture of living cells) requires host cells. but tricky and expensive (determine if have herpes. swab lesion, innoculate epithelial cell sheet, see them waste wuickly, flourecent tag on herpes antibodies, see all) -time consuming(weeks) and requires alot of resources and very highly skilled laboritory members
Serology (Measure antibodies against viral antigens in serum - IgM or IgG. Sero conversion.(when someone has lots of IgM antibodies-early antibodies which fight initial infections. If later seroconverted/changed to high levels of IgG- occurs when people get better. also evidence that was unwell. Note: sometimes IgM hangs around for long periods. easy to get confused.) Study of blood: study of proteins or antibodies in blood for specific virus (sometimes antigens) .Zika and Sara. Dangi fever protein NS1- rash. high fever. severe muscle aches and pains. Usually trying to detect antibodies. SARs not everyone had antibodies, only those inflected. (evidence immune memory has been evoked Influenza, everyone has antibodies, therefore need to detect Increase in antibodies) can be reliable but also messy/flasely hard to interpret Commonly used
How useful in serological diagnosis of influenza?
Detection of viral NA (PCR)- automatid process. main ways to diagnose viral infections. (if very sick e.g. pneumonia, take swab of nose to test for all respiratory viruses, as 20-30% of all pneumonia are caused by viruses) Main way to diagnose viruses.

Question 20

Management of Viral infections

Answer 20

1. Prevention(main) - vaccination/ immunisation. (hemophilis influenza B vaccine- used to kill children rapidly. supported by research. Epiglotisis and Meningitis used to be common, now gone away) (one of the 5 things that has lead to improved human health Avoidance.
2. Symptomatic management (want person to feel better when cannot do anything to help)(fever- given paracetomal- could be detrimental (e.g. chicken pox sicken for longer) (placebo better immune responses and faster recovery than ibiprofen and paracetomal. Accurate diagnosis.
3. Immune therapy
4. Specific antiviral drugs.(HIV requires HIV-targeting-antiviral drugs. to live normal health life of normal life span. (very close to normal)

Question 21

Last case of Small pox

Answer 21

erradicated by breaking down political and social divides re immunisation 2x cases.

1. get really sick and die
2. get sick but get better
   - some people more genetically susceptible.

Question 22

Polio cases in NZ

Answer 22

polio occurs in epidemics - early 1930s and big epidemic in late 19302

• robust, scientific evidence, that had a large number with polio and now none.
• Evidence that immunisations are effective
• polio affects respiratory muscles. no power to breathe in. Iron lungs, sucks and allows chest to expand, and then release and allows to breathe

Question 23

Other pathogens

Answer 23

Yeasts and molds

• Candidar infection in mouth and candidar plaques in throat
• candida albicans is normal part of human flora (in mouths all the time).
• Sometimes, certain illnesses/ given antibodies that kills bacteria but not candida yeast, can overgrow and flare- like in picture

Question 24

Bread mould

Answer 24

aspigilis fumigatus
almost never causes infections in humans
-except when immune system is really really compromised
-sometimes seen in sinuses or lungs of people undergoing chemotherapy for Leukemia

Question 25

Scabies

Answer 25

really really itchy, otherwise well

• Mite (only handful/five)
• poos under skin, immune system has allergic response, 3-4 weeks later itchy
• hard to locate mite

Question 26

African guni worm

Answer 26

1. Human drinks unfiltered water containing copepods with L3 larvae
2. Larvae released when copepods die. Larvae penetrate the host’s stomach and intestinal wall. They mature and reproduce
3. Fertilized female worm migrates to surface of skin, causes a blister, and discharges larvae
4. L1 larvae released into water from the emerging female worm
5. L1 larvae consumed by a copepod
6. Larvae undergoes two molts in the copepod and becomes a L3 larvae