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Phase 2a - Introductory Clinical Sciences > Microbiology and Infectious Disease > Flashcards

Microbiology and Infectious Disease Flashcards

1
Q

define pathogen

A

an organism that is capable of causing disease

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2
Q

define commensal

A

organism which colonises the host but does not cause disease in normal circumstances

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3
Q

define opportunist pathogen

A

microbe that only causes disease if host defences are compromised

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4
Q

define virulence/pathogenicity

A

the degree to which a given organism is pathogenic

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5
Q

define asymptomatic carriage

A

when a pathogen is carried harmlessly at a tissue site where it causes no disease

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6
Q

describe the structure of a Gram negative bacterial cell envelope

A 
inner cell membrane,
thin peptidoglycan layer,
outer cell membrane,
lipopolysaccharide layer,
outer capsule.
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7
Q

describe the structure of a Gram positive bacterial cell envelope

A

thick layer of peptidoglycan between the outer capsule + inner cell membrane.

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8
Q

what is a bacterial endotoxin? describe features

A

a component of the cell wall that is released when the bacteria is damaged.
less specific actions than an exotoxin e.g. septic shock

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9
Q

what is a bacterial exotoxin? describe features

A

mainly excreted by Gram +ve bacteria. actively secreted toxins with specific actions.

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10
Q

how might bacterial genes be transferred between bacteria?

A

transformation e.g. via plasmid.
transduction e.g. via phage.
conjugation e.g. via sex pilus.

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11
Q

describe the process of Gram staining

A
  1. heat fix sample to slide
  2. add methyl violet (blue/purple)
  3. add iodine - fixes methyl violet to gram +ve samples
  4. add alcohol to decolorize Gram -ve samples
  5. counterstain with basic fuchsin (red)
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12
Q

what is the normal habitat of staphylococcus spp?

A

nose and skin

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13
Q

how is S aureus spread?

A

aerosol and touch

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14
Q

what agar is used to grow enterobacteria?

A

MacConkey - bile salts, lactose, pH indicator

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15
Q

How do you distinguish Salmonella/Shigella from E coli on a MacConkey-lactose agar?

A 
E.coli = pink, as it is lactose fermenting
Shigella/salmonella = yellow, non-lactose fermenting
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16
Q

how would you distinguish between Salmonella and Shigella?

A

serology, as both are non-lactose fermenting so appear the same on MacConkey agar

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17
Q

what are the main infections caused by pathogenic E coli strains?

A 
wound infections (surgical).
UTIs.
gastroenteritis.
travellers' diarrhoea.
bacteraemia.
meningitis.
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18
Q

what 3 infections are caused by salmonella?

A
  1. gastroenteritis - food poisoning (localised infection)
  2. enteric fever - typhoid (systemic infection)
  3. bacteraemia - uncommon
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19
Q

what agar must H influenzae be grown on and why?

A

fastidious - requires haem and NAD - will not grow on blood agar, only chocolate agar (blood agar that has been heated so haem and NAD are released by RBCs).
non-motile.

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20
Q

describe the main features of Legionella pneumophila and Legionnaires’ disease

A

seen in immunocompromised (elderly, alcoholics, smokers).
severe.
culture on charcoal agar.
found in man-made aquatic environments - replicates within freshwater protozoa.
can infect alveolar macrophages.
induces phagocytosis.

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21
Q

what are the clinical features of an infection with campylobacter?

A

mild to severe diarrhoea, often with blood.
self-limiting (up to 1 wk).
campylobacter shed in faeces for 3wks.

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22
Q

describe the features of bacteroides? where are they typically found as commensals?

A

non-motile rods.
strict anaerobes.
commensal flora of large intestine (also commensal in vagina/cervix).

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23
Q

what shape are bacteroides?

A

bacilli

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24
Q

what shape are spirochaetes?

A

spiral/helical

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25
Q

describe the cell wall of fungi and how it stains?

A

rigid. polysaccharides and chitin.
stain with Gomorra methenamine silver, and periodic acid-Schiff.
lack a capsule.

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26
Q

describe the features of yeasts

A

unicellular.
round/oval.
asexual - reproduce by budding.

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27
Q

what are dimorphic fungi?

A

fungi which grow as yeasts in tissue, but as moulds in-vitro.

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28
Q

describe the features of moulds

A

composed of tubular structures (hyphae).
grow by longitudinal extension and branching - interwoven mycelium.
reproduce by spore formation (sexual/asexual).

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29
Q

what type of fungi is candida albicans?

A

yeast

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30
Q

give some examples of moulds

A

aspergillus spp.,
fusarium spp.
mucoraceous moulds.
dark-walled fungi.

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31
Q

what are the 3 types of fungal infection?

A
  1. superficial mycoses
  2. subcutaneous mycoses
  3. systemic mycoses
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32
Q

name some common sites for superficial mycoses

A

skin, hair, nails, mucous membranes

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33
Q

what are the two main kinds of infection seen in superficial mycoses?

A

ringworm.

yeast infections.

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34
Q

what pathogens cause ringworm (dermatophytosis, tinea - athletes foot, swimmers crotch etc)?

A

tricophyton spp.
microsporum spp.
epidermophyton spp.

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35
Q

describe the transmission of ringworm infections

A

direct or indirect transfer of infected keratin - e.g. communal bathing facilities.

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36
Q

describe the different types of aspergillus infection

A
  1. invasive aspergillosis - neutropaenic patients. treat with amphotericin.
  2. allergic aspergillosis - ABPA
  3. aspergilloma - fungus ball in pre-existing cavity of lung.
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37
Q

describe the basic idea behind the treatment of fungal infections, and give examples of drugs used.

A 
use drugs that target sterols in their cell membranes.
topical - nystatin, ketoconazole.
systemic:
oral - fluconazole/other azoles
parenteral - amphotericin.
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38
Q

give some examples of mycobacteria of medical importance, and the diseases they cause

A 
M. tuberculosis = TB
M. leprae = leprosy
M. kansaii = chronic lung infection
M. marinum = fish tank granuloma
M. ulcerans = buruli ulcer
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39
Q

why will immunocompromised patients show disseminated mycobacterial disease, instead of characteristic granulomas?

A

they don’t have enough T cell function to form granulomatas

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40
Q

describe the microbiological features of mycobacteria

A

aerobic, non-spore forming, non-motile bacilli.
cell walls contain a lot of high molecular weight lipids - weakly gram-positive/colourless.
slow growing.

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41
Q

what does the thick lipid coating of mycobacteria allow them to do?

A

survive inside macrophages, even in low pH environment

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42
Q

what are the key cell wall components of mycobacteria?

A

mycolic acids.

lipoarabinomannan

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43
Q

describe Koch’s postulates for a disease to be defined as caused by bacteria (/mycobacteria etc)

A
  1. bacteria should be found in all people with disease
  2. bacteria should be isolated from infected lesions
  3. a pure culture inoculated into a susceptible person should produce disease symptoms
  4. same bacteria should then be isolated from that individual
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44
Q

what stain is used for mycobacteria and why?

A

Ziehl-Neelsen stain for acid fast bacilli - high lipid content in cell wall makes mycobacteria resistant to Gram stain

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45
Q

what type of granuloma is typically seen in TB?

A

caseating

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46
Q

what are the main principles of mycobacterial treatment?

A
  1. slowly replicating bacteria - so need prolonged treatment
  2. multiple drug combinations to combat resistance
  3. compliance is essential - directly observe therapy used
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47
Q

describe the standard drug regime for tuberculosis

A

isoniazid, rifampicin, pyrazinamide and ethambutol for 2mths.
then isoniazid and rifampicin for 4 further months.

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48
Q

what makes up the primary complex of primary TB?

A

granuloma + lymphatics + lymph node

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49
Q

where in the lung are tuberculosis bacilli most likely to form a granuloma and why?

A

apex - there is more air and less blood supply, so fewer defending WBCs to fight

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50
Q

what is latent TB?

A

cell-mediated immune response from T cells manages to contain primary infection, but it persists.
no clinical disease (normal CXR).

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51
Q

what is pulmonary TB?

A

follows after primary disease, or after latent reactivation.

necrosis in lesion. caseous material coughed up, leaving cavity. TB may spread in lung causing other lesions.

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52
Q

where, apart from the lungs, may TB spread?

A 
GU TB
peritoneal TB
TB meningitis
widespread = miliary TB.
pleural TB
bone and joint TB
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53
Q

what are the three groups of helminths?

A
  1. nematodes (round worms)
  2. trematodes (flatworms, flukes)
  3. cestodes (tapeworms)
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54
Q

what do adult worms need before they can reproduce?

A

a period of development outside the body

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55
Q

what is the “pre-patent” period in relation to helminth disease?

A

the interval between infection and the appearance of eggs in the stool

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56
Q

how are intestinal nematodes transmitted?

A

faecal-oral route.

transmitted from person to person via eggs/larvae - these are only infectious after a period of development in the soil.

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57
Q

what organism causes pinworm/threadworm? what is the pre-patent period?

A

enterobius vermicularis
40d.
v common in UK!

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58
Q

describe the lifecycle of enterobius vermicularis (pinworm/threadworm)

A
  1. adult is resident in large bowel
  2. female emerges from anus at night to lay eggs on perineum
  3. eggs are infectious after 4hrs, ingested by next host
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59
Q

what are the clinical features of pinworm/threadworm?

A
  1. pruritis ani
  2. appendicitis
  3. vaginal penetration - endometriosis, salpingitis, infertility
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60
Q

how would you diagnose pinworm/threadworm?

A

microscopy of sellotape strip from perianal region

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61
Q

what is the general way to diagnose worms?

A

stool microscopy for eggs

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62
Q

what drug is used to treat a lot of worm infections? available in pharmacies for threadworm

A

Mebendazole

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63
Q

what causes schistosomiasis?

A

Schistosoma - an adult fluke. penetrate skin while swimming, mature in abdominal cavity.

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64
Q

what is schistosomiasis (katayama fever)? what are the clinical features?

A

initial immune-complex mediated illness 2-4wks after exposure.
fever; urticaria; eosinophilia; diarrhoea; hepatomegaly; splenomegaly; cough and wheeze; cachexia.

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65
Q

what are protozoa?

A

single-celled eukaryotes.

consume bacteria, algae, microfungi

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66
Q

what are the two main stages in the general life cycle of protozoa?

A

proliferative TROPHOZOITE stage - feed and reproduce.

dormant CYST stage - can survive outside host.

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67
Q

what are the 5 major groups that protozoa are divided into?

A
  1. flagellates
  2. amoebae
  3. cilliates
  4. microsporidia
  5. sporozoa
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68
Q

what are the 4 species of plasmodia that cause human disease?

A

P. falciparum
P. ovale
P. vivax
P. malariae

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69
Q

how is malaria transmitted?

A

bite of female Anopheles mosquitoes

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70
Q

how does the Anopheles mosquito become affected?

A

feeding from infected human. then they are infected for life (3-4wks). night-biting. bite indoors. lifecycle depends on water (to lay eggs)

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71
Q

describe the basic stages of the plasmodia lifecycle

A

in human host has exo-erythrotic cycle (in liver), and erythrotic cycle (in blood). (P ovale/vivax also have hypnozoite stage - lie dormant).
matures in RBCs.
taken up from blood into female anopheles - sporogonic cycle.

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72
Q

describe the pathogenesis of falciparum malaria

A

fatal.
parasite matures in RBCs - ‘knobs’ on RBC surface.
bind to receptors on endothelial cells in capillaries + venules.
sequestration in small vessels.
obstruction of microcirculation - tissue hypoxia.

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73
Q

what are the acute clinical features common to all 4 species of malaria?

A

FEVER.
chills and sweats; headache; myalgia; fatigue; nausea and vomiting; diarrhoea.
anaemia; jaundice; hepatosplenomegaly; ‘black water fever’

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74
Q

describe the clinical features of P falciparum malaria in adults

A

coma; ARDS; hypoglycaemia; renal failure (hypovolaemia, microvascular blockade).
SHOCK.

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75
Q

describe the clinical features of P falciparum malaria in children

A

non-specific - stop crying/playing/eating.
tachypnoea.
anaemia.
hypoglycaemia.
cerebral malaria can cause encephalopathy/coma - raised ICP, varied presentation - rule out meningitis.

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76
Q

how is malaria diagnosed?

A

thick AND thin blood films - 3 separate films at different times of day, examined under light microscopy.

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77
Q

how do you treat complicated falciparum malaria?

A

IV artesunate or IV quinine

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78
Q

how do you treat uncomplicated falciparum malaria?

A

oral riamet or oral quinine (±doxycycline)

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79
Q

how do you treat non-falciparum malaria?

A

oral chloroquine

80
Q

describe the stages of viral replication

A
  1. attachement
  2. cell entry - only viral ‘core’ enters host cytoplasm
  3. interaction with host cells - use cell materials for their replication etc
  4. replication
  5. assembly - may occur in nucleus/cytoplasm or at cell membrane
  6. release - by lysis of cell, or by exocytosis
81
Q

list the different ways in which viruses can cause disease

A
  1. direct destruction of host cells
  2. modification of host cell structure/function
  3. immuno-pathological damage
  4. damage through cell proliferation/immortalisation
  5. evasion of host defences
82
Q

what determines the defence mechanism employed against bacterial infection?

A

no. organisms/virulence.
low = phagocytes active
high = immune response

83
Q

what types of immunoglobulin are produced in response to worm infection?

A

IgG and IgE

84
Q

what is the most widely used antiviral agent? what is it’s mode of action?

A

aciclovir

nucleoside analogue

85
Q

how do nucleoside analogue antiviral agents work?

A

phosphorylated within cells to an active triphosphate and inhibit viral DNA synthesis

86
Q

what is septicaemia?

A

“blood poisoning” - when an infection is found in the circulating blood

87
Q

what are “notifiable diseases”? who should be notified?

A

diseases/infections/conditions that are specifically listed as notifiable.
local health authorities/Public Health England

88
Q

define “anti-microbial”

A

agents produced by microorganisms that kill or inhibit the growth of other micro-organisms in high-dilution

89
Q

what is the target site of beta lactams?

A

cell wall - inhibition of cell wall synthesis.

include penicillins, carbapenems and cephalosporins

90
Q

give examples of antibiotics that work by interference with nucleic acid synthesis/function

A

metronidazole

rifampicin

91
Q

how do metronidazole/rifampicin work?

A

interfere with nucleic acid synthesis or function

92
Q

how do fluoroquinolones work?

A

inhibit DNA gyrase

93
Q

what types of antibiotics work by inhibiting ribosomal activity and protein synthesis?

A

aminoglycosides.
tetracyclines.
macrolides.
chloramphenicol.

94
Q

what is the difference between bacteriostatic and bactericidal bacteria?

A 
bacteriostatic = prevent growth of bacteria.
bactericial = kills the bacteria
95
Q

what are the two major determinants of anti bacterial effect

A

concentration and time that the antimicrobial remains on binding sites

96
Q

what antibiotics put the patient at risk of C diff? (the 5Cs of C diff)

A

Ciprofloxacin; Clindamycin; Cephalosporins; Co-amoxiclav; Carbapenems

97
Q

what are 4 ways a bacteria may resist an antimicrobial?

A
  1. target site mutation
  2. destruction/inactivation of antimicrobial
  3. prevent antimicrobial access
  4. remove antimicrobial from bacteria
98
Q

how does beta lactamase confer resistance to penicillins and cephalosporins?

A

beta lactam ring is hydrolysed by this bacterial enzyme. antimicrobial is now unable to bind to the bacteria.

99
Q

give some examples of carbapenems and their uses

A

imipenem, meropenem, ertapenem.

broad spectrum - severe hospital acquired infections.

100
Q

give some examples of cephalosporins

A

cefradine
cefuroxime
cefotaxime

101
Q

give examples of glycopeptides, and how they are used

A

vancomycin , teicoplanin.
gram +ve agents.
IV only.
reserved for serious/resistant gram +ve, e.g. MRSA

102
Q

how does chloramphenicol work? how is it used?

A

it’s a protein synthesis inhibitor.
very broad spectrum (except pseudomonas).
toxicity - little used today.

103
Q

give examples of macrolides, and what they are used for

A

erythromycin, clarithromycin.

good for staph/strep. alternatives to penicillins. no gram-ve cover.

104
Q

what type of antibiotic is clindamycin? what is it used for?

A

lincosamides.

active against staph, strep and anaerobes

105
Q

give examples of aminoglycosides and what they are used for

A

gentamicin, tobramycin.

enterobacteriaceae, pseudomonas and staphylococci.

106
Q

what type of antibiotic is ciprofloxacin? what is it used for?

A

quinolones.

used against enterobacteriaceae, pseudomonas and staph.

107
Q

what types of organism is metronidazole active against?

A

anaerobic.

bacteria and protozoa.

108
Q

what does the catalase test differentiate between?

A

staphylococci - catalase +ve

strep and enterococci - catalase -ve

109
Q

what does the coagulase test differentiate between?

A

staph areus - coagulase +ve

other staph - coagulase -ve

110
Q

is staph aureus coagulase negative or positive?

A

positive

111
Q

what does the oxidase test aim to identify?

A

oxidase positive bacteria - pseudomonas spp. and neisseria spp.

112
Q

what does the optochin test do?

A

differentiates Strep pneumoniae from other alpa haemolytic strep.
strep pneumoniae shows a zone of inhibition around the optochin disc

113
Q

What types of bacteria form red/pink colonies on MacConkey agar?

A

E coli and Klebsiella - lactose fermenting

114
Q

What types of bacteria form a clear colony on MacConkey agar?

A

Salmonella, shigella, pseudomonas - lactose non fermenting

115
Q

what type of agar differentiates between alpha and beta haemolytic strep?

A

blood agar

116
Q

how do you identify alpha haemolytic strep (strep viridans) on blood agar?

A

green pigment due to partial breakdown of blood

117
Q

how do you identify beta haemolytic strep on blood agar?

A

clear zones around the colonies - complete breakdown of blood

118
Q

what is Lancefield grouping?

A

differentiates between beta haemolytic Strep spp. by detecting surface antigens

119
Q

which bacteria are in Lancefield groups A, B and D

A 
A = strep pyogenes
B = strep agalactiae
D = enterococci
120
Q

what are the 6 key Gram +ve staining bacterial groups?

remember - Sexy Students Can Look Bad Come morning

A 
Streptococcus
Staphylococcus
Corynebacterium
Listeria
Bacillus
Clostridium
121
Q

are the 6 key groups of Gram +ve bacteria aerobic or anaerobic?

A

aerobic, apart from Clostridium spp which are anearobes

122
Q

describe the key features of streptococcus spp

A

chains or diplococci.
gram +ve.
catalase negative.
aerobic.

123
Q

describe the features of strep pneumoniae and what diseases it can cause

A

gram +ve diplococci. alpha haemolytic. droplet transmission.

community-acquired pneumonia, sinusitis, bacterial meningitis.

124
Q

what antibiotics would be given to treat strep pneumoniae infection?

A

penicillin or erythromycin

125
Q

what diseases are caused by alpha haemolytic strep (strep viridans)

A

bacterial endocarditis + dental caries.

126
Q

how would you treat an alpha haemolytic strep infection?

A

penicillin/amoxicillin (erythromycin if allergic).

bacterial endocarditis - penicillin and gentomycin.

127
Q

give the features of strep pyogenes, and the diseases it causes?

A

group A beta-haemolytic.
transmission is airborne and hands.
cellulitis, necrotising fasciitis, pharyngitis (strep throat), tonsillitis etc

128
Q

what are the features of enterococcus spp and what diseases do they cause?

A

group D, non-haemolytic, MacConkey growth. GI tract commensal.
infective endocarditis, UTIs, would infections, IV catheter infections.

129
Q

how would you treat an enterococcus infection?

A 
pencillin/vancomycin.
serious infection (e.g. IE) - penicillin/vancomycin + getamicin
130
Q

describe the key features of staphylococcus spp.

A

cocci in clumps, Gram +ve.

catalase positive. coagulase used to differentiate staph aureus (+ve) from the others. aerobic.

131
Q

name two coagulase -ve staphylococcus spp.

A

staph epidermidis

staph saprophyticus

132
Q

give some diseases caused by staph aureus

A 
Impetigo, cellulitis, wound infection.
osteomyelitis, septic arthritis.
conjunctivitis.
bacterial endocarditis (in IVDU)
pneumonia.
133
Q

how would you treat a staph aureus infection?

A

flucloxicillin.

MethicillinRSA isn’t sensitive to flucloxacillin - use vancomycin instead.

134
Q

give a disease caused by staph saprophyticus and its treatment?

A

UTI in sexually active young women.

trimethoprim, flucloxacillin.

135
Q

what is the important species of Corynebacterium? how is it spread? what disease does it cause?

A

Corynebacterium diphtheriae.
droplet spread.
diphtheria.

136
Q

how would you treat diphtheria?

A

erythromycin.

diphtheria antitoxin.

137
Q

are Clostridium spp aerobic or anaerobic?

A

anaerobic

138
Q

what bacteria causes tetanus? how is it spread? how would you treat it?

A

clostridium tetani.
spore-forming - spores enter open wounds.
human tetanus Ig + benzodiazepines.

139
Q

what disease does C difficile cause? how does it spread?

A

transmission = spores via faecal-oral route.

causes pseudomembranous colitis - diarrhoea following antibiotic therapy.

140
Q

how would you treat C diff diarrhoea?

A

vancomycin

141
Q

what are the 6 important Gram -ve bacterial groups?

A 
Neisseria
Coliforms (also Enterobacteriaceae)
Parvobacteria
Helicobacter
Vibrio
Pseudomonas
142
Q

Are the key Gram -ve bacterial groups aerobic or anaerobic?

A

aerobic

143
Q

describe the features of Neisseria spp.

A

diplococci. gram -ve. oxidase positive. aerobic.

144
Q

Neisseria meningitidis - give its transmission, diseases caused and treatment

A

transmission is by droplets/direct mucosal contact.
Causes meningitis and septicaemia (with purpuric skin rash).
treatment - benzylpenicillin or cefotaxime.

145
Q

what disease does Neisseria gonorrhoea cause? transmission? treatment?

A

gonorrhoea. (opthalmia neonatorum, Reiter’s syndrome).
transmission is direct mucosal contact.
treatment = ciprofloxacin or cefixime.

146
Q

List the coliforms (/enterobacteriaceae) according to colour on MacConkey agar

A

red/pink colony = E coli and Klebsiella penumoniae.

clear colony = Salmonella typhi, paratyphi (A, B, C) and enteritidis

147
Q

E coli: transmission? diseases caused?

A

faecal-oral.

diarrhoea. UTIs, hospital-acquired pneumonia.

148
Q

Klebsiella pneumoniae: diseases caused? treatment?

A

hospital acquired pneumonia. UTIs.

cephalosporins.

149
Q

what diseases do Salmonella typhi and paratyphi cause? transmission and treatment?

A

typhoid and paratyphoid (enteric fever).
faecal-oral.
ciprofloxacin.

150
Q

what disease does Salmonella enteritidis cause? transmission? treatment?

A

gastroenteritis (food-poisoning). transmitted in under-cooked food contaminated with infected animal faeces. no treatment - self-limiting disease.

151
Q

what disease does Shigella dysenteriae cause? transmission and treatment?

A

bacillary dysentery. faecal-oral. ciprofloxacin.

152
Q

give some examples of parvobacteria

A

Haemophilus influenzae, Bordatella pertussis, Legionella pneumophila, Campylobacter jejuni.

153
Q

what diseases does Haemophilus influenzae cause?

A

meningitis, osteomyelitis, cellulitis, otitis media, septic arthritis, pneumonia.

154
Q

how would you treat an H influenzae infection?

A

cefotaxime or ceftriaxone

155
Q

what disease does Bordatella pertussis cause? transmission and treatment?

A

whooping cough. airborne droplets. erythromycin.

156
Q

what disease does Legionella pneumophila cause? transmission and treatment?

A 
Legionnaires disease (severe pneumonia, high fever). transmitted by aerosolised droplets - found in warm water such as air con units, water tanks.
treat with erythromcyin.
157
Q

what does Campylobacter jejuni cause? transmission? treatment?

A

gastroenteritis ± dysentery - food poisoning.
reactive arthritis.
Guillain-Barre.
transmitted in contaminated poultry or unpasteurised milk.
no treatment - self-limiting.

158
Q

what diseases does H pylori cause? how would you treat?

A

chronic gastritis. duodenal and gastric ulcers. increased gastric cancer risk.
treat - clarithromycin and amoxicillin or metronidazole.
PPI (omeprazole).

159
Q

what disease does Vibrio cholerae cause? transmission and treatment?

A

cholera - rice water diarrhoea, 25l/day.
faecal-oral / seafood.
treat - rehydration.

160
Q

what diseases does pseudomonas aeruginosa cause?

A

pneumonia (esp. in CF patients).
IV catheter infections.
folliculitis.
UTIs, esp. with catheters.

161
Q

how would you treat a patient with a Pseudomonas aeruginosa infection?

A

severe cases - gentamicin or ceftazidime (IV).

in CF/bronchiectasis - ciprofloxacin.

162
Q

what 8 important bacterial groups stain poorly/not at all with Gram stain?

A 
Chlamydia spp.
Coxiella spp.
Ricksettia spp.
Mycobacteria spp.
Trepnonema spp.
Borrelia spp.
Leptospira spp.
Mycoplasma spp.
163
Q

What diseases are caused by Chlamydia trachomatis?

A

chlamydia.
trachoma - chronic follicular keratoconjunctivitis.
Reiter’s syndrome/
PID.

164
Q

what is the route of transmission of Chlamydia trachomatis?

A

mucosal contact

165
Q

how would you treat a patient infected with Chlamydia trachomatis?

A

doxycycline or azithromycin

166
Q

what disease is caused by Chlamydia psittaci? treatment?

A

pigeon fanciers lung. tetracylcine.

167
Q

what culture medium is used for Mycobacteria? how long should the culture be grown for?

A

Lowenstein-Jensen culture medium. up to 12 weeks.

168
Q

what disease is caused by Mycobacterium leprae? transmission and treatment?

A

Leprosy. aerosol droplet spread.

Rifampicin and dapsone.

169
Q

what disease is caused by Treponema pallidum? transmission and treatment?

A

Syphillis. tramission is through broken mucosa during sexual contact, or blood transfusion.
treatment - penicillin or doxycycline.

170
Q

give some examples of spirochaete bacteria

A

Treponema spp.
Borrelia spp.
Leptospira spp.

171
Q

what type of virus is the herpes simplex virus? what diseases does it cause?

A

DNA virus.
HSV1 = cold sores.
HSV2 = genital herpes.

172
Q

how would you treat a herpes simplex infection?

A

aciclovir, famciclovir or valciclovir

173
Q

what type of virus is the varicella-zoster virus? what diseases does it cause?

A

DNA virus.
chicken pox.
reactivation = shingles.

174
Q

how would you treat someone infected with varicella zoster?

A

child - calamine lotion.

adolescents/adults - aciclovir.

175
Q

what type of virus is cytomegalovirus?

A

DNA virus.

176
Q

what type of virus is Epstein-Barr virus? what diseases does it cause?

A

DNA virus.
infectious mononucleosis (Glandular fever).
Burkitt’s lymphoma/Hodgkin’s disease.

177
Q

what type of virus is the influenza virus? how is it transmitted?

A

RNA virus.

droplet spread.

178
Q

what type of virus is the mumps virus? how is it transmitted?

A

RNA virus.

droplet spread.

179
Q

what are the clinical features of mumps?

A

prodrome - headache, malaise, fever.
enlarged parotid gland.
orchitis.

180
Q

what type of virus is the measles virus? how is it spread?

A

RNA virus.

droplet spread.

181
Q

what are the clinical features of measles?

A

Prodromal illness.

fever. rash - erythematous and maculopapular.

182
Q

what type of virus is the coronavirus? what does it cause? how it is spread?

A

RNA virus.
common cold.
droplet spread.

183
Q

what type of virus is the rotavirus? what does it cause? how is it spread?

A

RNA virus.
gastroenteritis.
faeco-oral + direct spread.

184
Q

name two groups of yeasts

A

candidia spp. and cryptococcus spp.

185
Q

where is Candida albicans found? how is it transmitted?

A

oropharynx, vagina, GI tract.

disruption of normal bacterial flora leads to Candida overgrowth.

186
Q

what diseases does Candida albicans cause?

A

vaginal and oral candidiasis (thrush).
skin/nail infections.
UTIs.

187
Q

what type of protozoa is entamoeba histolyica? what disease does it cause?

A

an amoeba.

causes amoebic dysentry - faeco-oral transmission.

188
Q

what are the clinical features of amoebic dysentery?

A

abdo pain.
severe diarrhoea with blood and mucus.
tenesmus.
hepatomegaly.

189
Q

how would you treat amoebic dysentery?

A

metronidazole.

190
Q

what type of protozoa is giardia lamblia? what disease does it cause?

A

flagellate.
causes diarrhoea, including travellers diarrhoea.
faeco-oral.

191
Q

give an example of a cestode

A

taenia solium - pork tapeworm

192
Q

give an example of a trematode

A

schistosomes

193
Q

what colour do Gram +ve bacteria stain?

A

Purple (Positive = Purple)

194
Q

what colour do Gram -ve bacteria stain?

A

red/pink

195
Q

what worm is the most common cause of iron-deficiency anaemia worldwide?

A

hookworm

Phase 2a - Introductory Clinical Sciences (6 decks)

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