Microbiology Flashcards
1
Q
Define microbiology
A
Microbiology= the study of living microorganisms
2
Q
What are the microorganisms that have medical importance
A
- ) Bacteria
- ) Viruses
- ) Fungi
- ) Mycobacteria
- ) Protozoa
- ) Worms
3
Q
Describe bacteria
A
- Bacteria enter host via resp/break in skin/break in mucous membrane/GI tract/GU tract
- They sequester nutrients to outcompete micro-organisms
- They sense change via cell density
- They express toxins (toxins=are classified by he tissue they target or molecular actions). These toxins are encoded on chromosomes or plasmids
- Action of these toxins: produce adhesives which help bacteria to bind to mucosal surface
4
Q
Describe viruses
A
- A virus is an infectious obligate intracellular parasite comprising of genetic material (DNA or RNA) surrounded by a capsid (protein coat).
- They have various shapes including helical and icosahedral
- E.g. E-coli
5
Q
Describe the body’s response to a bacterial pathogen
A
- Bacteria will elicit an antibody response UNLESS it is intracellular: then it becomes a cell mediated response
- Three things involved in the host response to bacterial infection:
1. ) IgA
2. ) AbC3b
3. ) Complement - Will get a delayed type-hypersensitivity: an immune response that occurs via delayed activation of T-cell types
- PRR recognise PAMPS on bacteria-> result in inflammatory cytokine or type I interferon expression
6
Q
Describe mycobacteria
A
- Mycobacteria are slow growing, rod shaped, gram positive bacilli that are acid-fast (test w the Ziehl-Neelsen test)
- Has high lipid content with mycolic acids in cell wall
- Aerobic/survive in macrophages/slow growing
- The three main groups:
1. ) M.tuberculosis (most important one)
2. ) Nontuberculous mycobacteria (NTM)
3. ) Mycobacterium leprae
7
Q
Describe protozoa
A
- Protozoa = single celled organisms with nucleus (eukaryotic)
- Classified into key categories (with example):
1. ) Flagellates - giardia lamblia
2. ) Amoebae - Entamoeba histolytica
3. ) Sporozan - cryptosporidium spp
4. ) Ciliates - balantidium coli
5. ) Microsporidia
8
Q
List the two main types of immunisation
A
Passive and active
9
Q
Define passive immunisation
A
The administration of pre-formed ‘immunity’ from one person to another person
10
Q
Give advantages of passive immunisation
A
- Provides immediate protection
- Is effective in immunocompromised patients
11
Q
Give disadvantages of passive immunisation
A
- Effects are short lived
- No boosting on exposure to pathogen
- Possible transfer of pathogens
- Only works if protection against the disease is mediated by an antibody
12
Q
List examples of passive immunisation
A
- ) HTIG (tetanus)
- ) Human rabies
- ) HBIG (hep B)
- ) VZIG (varicella zoster
- ) HNIG
13
Q
List the diseases that have an available vaccine
A
- ) Polio vaccine
- ) Influenza vaccine
- ) Hepatitis A vaccine
- ) Rabies vaccine
- ) Rotavirus
- ) MMR vaccine
14
Q
Define a non-living vaccine (whole killed/toxoids)
A
This is when bacteria or viruses are grown in vitro and inactivated using agents such as formaldehyde or beta-propiolactone
15
Q
What is an advantage of a non-living vaccine
A
It won’t cause infection but the antigens it contains induces an immune response which protects against infection
16
Q
Describe some of the limitations of non-living vaccines
A
1.) Whole pathogens may cause excessive reactogenicity ad the immune response is not always like the normal response to infection
17
Q
Give examples of non-living vaccines
A
1.) Bacterial: diphtheria toxoid, cholera heat killed bacteria, tetanus toxins
18
Q
Give examples of non-living vaccines
A
- ) Bacterial: diphtheria toxoid, cholera heat killed bacteria, tetanus toxins
- ) Viral: Poli/influenza/hepatitis A/rabies vaccines
19
Q
Describe the process of exposure in pathogenesis
A
- exposure via ingestion: e.g. how salmonella and shigella enter the body
or via inhalation e.g. streptococcus
or wound e.g. clostridium tetani
20
Q
Describe the process of adherence in pathogenesis
A
- bacteris have fimbriae or pili with adhesives
e. g. the adhesives of Neisseria gonorrhoeae bind to oligosaccharide receptors on epithelial cells
21
Q
Describe the process of invasion in pathogenesis
A
-formation of biofilm: sticky webs of bacteria
22
Q
Describe the process of infection in pathogenesis
A
- By products can cause tissue damage
- bacteria produce toxins and cause cell lysis/trigger destructive immune responses
23
Q
Describe the process the pathogen exiting the host in pathogenesis
A
- alter their surface proteins
- hide within cells in the body
- inactive defences
24
Q
Give examples of conjugation vaccines
A
- Neisseria meningitis type C
- Streptococcus pneumoniae-23
- Haemophilus influenzae type B
- Malaria
25
Describe the methods for preventing and controlling infections
- Identify risks: to do with the patient and environment
- Develop strategies to reduce the risks via policy development/education/audit:
- Environment: design, cleaning, isolation
- Patients: isolation, antimicrobial stewardship
- Staff: barrier precautions (PPE), isolation, handashing, disposal of sharps
26
Give some examples of diseases that can spread in hospital
- MRSA
- norovirus
- C difficile
27
Describe malaria and species that act as vectors
- Malaria is a type of protozoa that is transmitted by bite of a female anopheles mosquito. 5 species include:
1. ) Plasmodium falciparum (most severe one)
2. ) Plasmodium vivax
3. ) Plasmodium malariae
4. ) Plasmodium knowlesi
28
What signs present malaria
- Anaemia
- Jaundice
- Hepatosplenomegaly
29
Describe some of the common symptoms of malaria
- Fever
- Chills
- Headache
- Myalgia
- Fatigue
- Vomiting
30
Describe the symptoms you would get with falciparum (more severe as causes microcirculation)
- Cerebra; malaria
- ARDs (acute respiratory distress syndrome
- Renal failure
- Bleeding
- Shock
31
How would you investigate and diagnose malaria
1.) Light microscopy via a blood sample in:
- thick film: does person have malaria or not
- thin film: what species of malaria do they have
OR a rapid diagnostic test: this will detect plasmodium antigens in blood
32
Describe the treatment for malaria
- IV artesunate
or
- IV quinine + doxycycline
33
Define active immunisation
When the immune system is stimulated to produce antibodies against a particular infectious agent
34
Give advantages of active immunisation
- Protection is long lived
- Less costly to administer than passive
- Active immunisation may be reactivated quickly
35
Give disadvantages of active immunisation
- Not suitable as a post exposure remedy
| - May not be suitable for immunocompromised patients
36
List examples of active immunisations
1. ) Smallpox vaccination
| 2. ) TB vaccine
37
What are some examples of viral infections
- CMU: Cytomegalovirus
- Influenzas
- Epstein Barr Virus (EBV)
- Human Papilloma Virus (HPV)
- Measles
38
Describe some important examples of flagellates (protozoa)
1. ) African Trypanosmiasis (sleeping sickness: transmitted via tsete fly
2. ) Americann Trypanosomiasis (changas disease): can be asymptomatic, has acute (get romana sign and lymphadenopathy)+ chronic phase (get cardiomyopathy)
3. ) Leishmaniasis: cutaneous, produces ulcers, spread via infected sand-fly
39
Describe some important examples of flagellates (protozoa)
1. ) African Trypanosmiasis (sleeping sickness: transmitted via tsete fly
2. ) Americann Trypanosomiasis (changas disease): can be asymptomatic, has acute (get romana sign and lymphadenopathy)+ chronic phase (get cardiomyopathy)
3. ) Leishmaniasis: cutaneous, produces ulcers, spread via infected sand-fly
4. ) Giardiasis (important): spread via faecal-oral route/get cramps, bloating + flatulence/trophozoites seen in stool/treat with metronidazole
40
Describe some important examples of flagellates (protozoa)
1. ) African Trypanosmiasis (sleeping sickness: transmitted via tsete fly
2. ) Americann Trypanosomiasis (changas disease): can be asymptomatic, has acute (get romana sign and lymphadenopathy)+ chronic phase (get cardiomyopathy)
3. ) Leishmaniasis: cutaneous, produces ulcers, spread via infected sand-fly
4. ) Giardiasis (important): spread via faecal-oral route/get cramps, bloating + flatulence/trophozoites seen in stool/treat with metronidazole
5. ) Trichomonas Vaginalis: get dysuria and yellow frothy discharge
41
Give an example of an amoebae (protozoa)
Amoebiasis (Entamoeba histolytic):
- faecal-oral spread
- get dysentery/colitis
- trophozoites in stool
42
Give some examples of sporozoa (protozoa)
1. ) Cryptosporidiosis: waterborne/get diarrhoea/oocytes seen in stool
2. ) Toxoplasmosis: get via ingestion of contaminates food/
3. ) Malaria
43
Describe fungi
- Fungi kingdom has 6 elements:
1. ) Microsporidia
2. ) Chytridiomycota
3. ) Blastocladiomycota
4. ) Zygomycota
5. ) Glomeromycota
6. ) Basidiomycota
7. ) Ascomycota
44
Describe the main forms of fungal infections
1. ) Skin infections: caused by dermatophytes (microspora/epidermophyton/trichophyton): e.g. athletes foot
2. ) Mucosal Infection
3. ) Invasive infection:
- candidiasis
- aspergillosis
- pneumocystis pneumonia
- Cryptococcus
45
Describe worms
X
46
Examples of gram negative enterobacteria
1. ) E.coli: EPEC/ETEC (small intestine) + EHEC/EIEC/EAEC (large intestine)
2. ) Shigella: S.dysenteriae/S.flexneri/S.boydi/S.sonnei
3. ) Salmonella: S.enterica/S.bongori
4. ) Gastroenteritis/enterocolitis (Serovars Enteritis + Typhimurium)
5. ) Enteric fever: typhoid (serovars Typhi + Paratyphoid)
6. ) Bacteraemia (serovars Cholerasuis and bublin)
7. ) Proteus mirabilis
8. ) Klebsiella pneumoniae
9. ) Enterobacteria (not in cc)
10. ) Yersinia spp (not in cc)
47
Describe e-coli
x
48
Describe shigella
x
49
Describe salmonella
x
