Medical Microbiology

Question 1

non sterile body sites

Answer 1

mouth, oesophagus, lungs, stomach, intestine

Question 2

sterile body sites

Answer 2

brain, heart, liver, kidney

Question 3

common specimen types collected to diagnose infection

Answer 3

MSSU (urine), sputum, throat swab, swabs, faeces, blood culture, cerebrospinal fluid, aspirate of pus, bone

Question 4

what is role of culture microscopy in diagnosis of bacterial infection

Answer 4

non specific but assists provisional diagnosis and empiric antimicrobial therapy

Question 5

methods of detecting viruses

Answer 5

molecular methods- PCR, antigen detection, serology to determine immunity, electron microscopy, cell or tissue culture

Question 6

main structures of bacterial cell

Answer 6

chromosome, cytoplasm, cell wall, ribosome, penicillin binding proteins, lipopolysaccharide, capsule, flagella, fimbriae, plasmid, bacteriophage, spores, peptidoglycan

Question 7

how do bacteria replicate and create genetic variation

Answer 7

binary fission and transfer DNA via plasmids, spontaneous mutation

Question 8

how is bacteria detected

Answer 8

individual can only be seen with a microscope. use stains like gram stain and fluorescent dyes

Question 9

lysis

Answer 9

wall is weakened or ruptured so cell swells and bursts due to osmosis

Question 10

lipopolysaccharide

Answer 10

only present in gram negative bacteria, protects peptidoglycan from bile salts and blocks antibiotics from getting into cell.

Question 11

lipid A

Answer 11

in lipopolysaccharide. forms endotoxin which may give rise to endotoxin shock if released in bloodstream- fever and low blood pressure

Question 12

bacteriophages

Answer 12

virus that infects bacteria

Question 13

what is Svedberg unit

Answer 13

measure of sediment rather than size

Question 14

how is bacteria cultured

Answer 14

agar. colonies can be seen by eye

Question 15

main groups of parasites

Answer 15

protozoa(malaria), helminths (tapeworms), ectoparasites (lice)

Question 16

protozoa

Answer 16

able to multiply in humans. transmitted by faecal- oral route or insect vector. amoebic dysentry and plasmodium causing malaria is example

Question 17

common diseases caused by enteric and blood borne parasites

Answer 17

Schistosomiasis, malaria, pinworms,

Question 18

how is parasitic infection diagnosed (3)

Answer 18

identification of parasites in host tissue or faeces or urine. blood microscopy, stool microscopy- look for ova, cysts, parasites. Indirect testing- rapid diagnostic test or serology

Question 19

nematodes transmission route

Answer 19

faecal oral eg pinworm

Question 20

cestodes transmission route

Answer 20

eating raw or uncooked meat. use a intermediary host eg beef tapeworm

Question 21

trematodes transmission route

Answer 21

contact with freshwater where the snail intermediary host is present eg schistosomiasis

Question 22

virion structure

Answer 22

lipid envelope around the outside with spike projections, protein capsule on inside, virion associated polymerase inside of that

Question 23

virus replication

Answer 23

enter cell, uncoated, genomic nucleic acid replicated in the nucleus, mRNA synthesis, protein synthesis, newly synthesised virus proteins inserted into membrane and genomic nucleic acid put into virion again and then budded and released with lipid envelope back on. mature and then attach and enter another cell again

Question 24

types of transmission of virus

Answer 24

blood borne, sexual, airborne, droplet, faecal oral, close contact

Question 25

why is confection of human and animal or bird strains in one generation dangerous

Answer 25

may lead to recombination and generation of a new strain

Question 26

consequences of viral infection

Answer 26

clearance of virus (with short, no, or long term immunity), chronic infection, latent infection, transformation

Question 27

viral latency

Answer 27

after primary infection, viruses lie dormant in cell, viral genome is retained, reactivation of viral replication can occur and this may or may not cause apparent disease. bad for immunocompromised. examples- herpes simplex virus

Question 28

how can viruses lead to cancer

Answer 28

modulation of cell cycle, modulation of apoptosis, reactive oxygen species mediated damage

Question 29

all antiviral agents are ____ none are _____

Answer 29

virustatic, virucidal

Question 30

antivirals can be used for

Answer 30

prophylaxis (to prevent infection), pre-emptive therapy (evidence of infection detected but before symptoms apparent), overt disease, suppressive therapy (to keep viral replication below rate that causes tissue damage)

Question 31

ways of preventing viral infection

Answer 31

immunisation, prophylactic treatment post exposure, infection prevention and control measures, blood/tissue/organ screening, antenatal screening

Question 32

what is a fungus

Answer 32

chemo-organotrophic eukaryote that lacks chlorophyll and forms spores. absorbs nutrients

Question 33

what does a fungal membrane contain as the major sterol

Answer 33

ergosterol

Question 34

3 major groups of fungi

Answer 34

basidiomycetes, ascomycetes, zygomycetes

Question 35

dermatophyte fungi that cause skin infections main virulence factor is

Answer 35

enzymes that degrade and utilise keratin as a nutrient source

Question 36

malassezia species role in health and disease

Answer 36

colonisers of healthy skin, especially sebum rich areas,. can cause superficial infections in susceptible skin and wide range of infections in immunocompromised and premature neonates

Question 37

host factors that contribute to pathogenicity of fungal infections

Answer 37

favourable microenvironments, broad spectrum antibacterial agents, immunosuppression

Question 38

forms of immunosuppression of host defences

Answer 38

latrogenic(steroids, anti cancer chemotherapy), disease processes(AIDS leukaemia) or combination of both

Question 39

candida infections human diseases

Answer 39

oral, penis, vaginal, skin, urinary tract infections

Question 40

what kind of species are candida species

Answer 40

yeast

Question 41

what can Candida albicans form

Answer 41

hyphae

Question 42

thrush is caused by what fungal infection

Answer 42

candida

Question 43

aspergillosis route of infection

Answer 43

inhalation of conidia which germinate to hyphae in lung tissue. it is angioinvasive also

Question 44

types of disease caused by aspergillosis

Answer 44

simple asthma, asthma with eosinophilia, aspergilloma

Question 45

human diseases caused by cryptococcosis

Answer 45

pulmonary cryptococcosis, meningitis, diessemated infection in severely compromised hosts

Question 46

what is the damage response interaction

Answer 46

fungal infections. means that if the host response to the infection is too strong or too weak, this will result in disease

Question 47

how to detect fungal infections

Answer 47

direct detection- histopathology, high res CT scans, growth on selective medium PCR for fungal DNA, detection of circulating antibodies to fungi

Question 48

problems with anti fungals

Answer 48

cost, static, IV vs oral, toxicity, resistance

Question 49

types of anti fungal agents

Answer 49

polyenes, azoles, echoinocandins

Question 50

what type of bacteria form spores

Answer 50

bacilli and clostridium

Question 51

spirochaetes

Answer 51

spiral shaped bacteria causing syphilis, lames disease, relapsing fever

Question 52

examples of genera of spirochetes

Answer 52

Spirochaeta, Treponema, Borrelia, and Leptospira

Question 53

bacterial typing

Answer 53

way of identifying strains of microorganisms

Question 54

fimbriae and pili

Answer 54

thin protein tubes that extend out of bacteria and help them with adhesion to surfaces. pili are longer and fewer. found in gram negative bacteria but not gram positive