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Phase 2a > Microbio > Flashcards

Microbio Flashcards

1
Q

What are the sterile areas in the body?

A

Lungs (lower resp tract)
Blood
Gallbladder
Kidneys
CSF
Joints
Bladder
Pleural fluid
Peritoneal cavity

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2
Q

What areas of the body are colonised with flora?

A

GI tract
Skin
Oral cavity
Vagina
Urethra

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3
Q

Examples of gram positive cocci

A

staphylococci
streptococci
enterococci

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4
Q

Examples of gram positive bacilli

A

b. anthracis
c. diptheria
clostrididia

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5
Q

Examples of gram negative cocci

A

neisseria
moraxella

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6
Q

Examples of gram negative bacilli

A

E.Coli
salmonella
shigella
pseudamonas
v.cholerae

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7
Q

Gram positive aerobic cocci in clusters

catalase positive

A

STAPHYLOCOCCUS
Coagulase positive: s. aureus
Coagulase negative: s. epidermis, s. soprophitious

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8
Q

Gram positive cocci aerobic in chains

catalase negative

A

STREPTOCOCCUS

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9
Q

alpha haemolytic strep

A

s. pneumoniae
viridans group strep

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10
Q

beta haemolytic strep

A

s. pyogenes (Group A)
Group B
Group G

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11
Q

Non-haemolytic strep

A

Group D (s. bovis)

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12
Q

Examples of spirochaetes

A

treponema
leptospira
borrelia

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13
Q

How does gram staining work?

A

differentiates bacteria by the chemical and physical properties of their cell walls through detecting peptidoglycan, which is present in the cell wall of gram-positive bacteria.

PURPLE POSITIVE PEPTIDOGLYCAN

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14
Q

Gram negative anaerobic bacilli

A

bacteroides

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15
Q

Gram negative aerobic lactose fermenting bacilli

A

E.Coli
Klebsiella

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16
Q

Gram negative aerobic non lactose fermenting bacilli

A

salmonella
shigella
proteus
pseudomonas

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17
Q

gram negative aerobic bacilli (lactose fermenting doesn’t apply)

A

vibrio
campylobacter
helicobacter
haemophilus

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18
Q

Gram positive aerobic bacilli

A

listeria
bacillus
corynebacterium

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19
Q

Gram positive anaerobic bacilli

A

Clostridium
Propionibacterium

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20
Q

Ziehl-neelsen/ acid fast positive bacilli

A

Mycobacteria

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21
Q

What is the process of gram staining?

A

Crystal violet
Iodine
Decolourisation (negative lose purple at this point)
Counter stain:
- positive stay purple
- negative are pink

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22
Q

How does staph aureus present on blood agar?

A

gold/yellow

aureus means gold

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23
Q

What is blood agar used for?

A

medium for lots of bacteria types to grow

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24
Q

description of chocolate agar

A

blood agar heated at 80 degrees for 5 mins to release nutrients and make growth easier

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25
Q

What is CLED agar used for?

A

non-inhibitory growth medium
differentiates microorganisms in urine
classification of lactose fermenting (yellow on CLED) and non LF (blue on CLED)

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26
Q

description of MacConkey agar

A

gram negative bacilli
bile salts inhibit gram positive
lactose fermenting are pink, NLF yellow

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27
Q

Description of gonococcus agar

A

growth factors for neisseria gonorrhoea
abx and antifungals inhibit growth of other organisms

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28
Q

description of XLD agar

A

selective to isolate salmonella (red and black) and shigella (red)

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29
Q

what is sabouraud’s agar used for?

A

culturing fungi
bacteria inhibited by abx in agar

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30
Q

What is the coagulase test used for?

A

differentiating between pathogenic and non-pathogenic strains of staph
bacteria that produce coagulase clot plasma around them to resist phagocytosis

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31
Q

What is strep pneumoniae sensitive to that other alpha haemolytic streps aren’t?

A

optochin test

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32
Q

How are beta-haemolytic strep differentiated?

A

Lancefield grouping

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33
Q

How do beta-haemolytic appear on agar?

A

completely haemolyse blood cells so have a clear zone

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34
Q

What is serology?

A

study of antibody responses in the serum

particulary IgG and IgM

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35
Q

What is meningitis?

A

inflammation of the pia and arachnoid mater
Micro-organisms infect the cerebrospinal fluid (CSF).

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36
Q

What are the 3 symptoms associated with meningism?

A

stiffness of the neck
photophobia
severe headache

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37
Q

What are common bacterial causes of meningitis?

A

neisseria meningitis (gram neg diplococci)
strep pneumoniae (gram positive diplococci)

also: e.coli in neonates and haemophilus influenza in infants

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38
Q

What is encephalitis?

A

inflammation of cerebral cortex

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39
Q

What are the symptoms of encephalitis?

A

lethargy
fatigue
decreased consciousness
fever

+ meningism = meningo-encephalitis

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40
Q

What virus normally causes encephalitis?

A

almost always Herpes simplex virus
occasionally Varicella zoster virus, Parvoviruses, primary HIV, Mumps virus, Measles virus

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41
Q

What is a pathogen?

A

Organism that causes or is capable of causing disease

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42
Q

What is a commensal?

A

Organism which colonises the host but causes no disease in normal circumstances

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43
Q

What is an opportunistic pathogen?

A

Microbe that only causes disease if host defences are compromised

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44
Q

What is virulence?

A

The degree to which a given organism is pathogenic

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45
Q

What is asymptomatic carriage?

A

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

46
Q

What are some obligate intracellular bacteria?

A

Rickettsia
Chlamydia
Coxiella

47
Q

How do beta-lactam abx work?

A

attack peptidoglycan in cell wall
good in gram positive

48
Q

Examples of beta-lactams

A

Penicillins (fluclox is what MRSA is resistant to)
Cephalosporins
Carbapenems

49
Q

Examples of cephalosporins

broad spectrum

A

Cefuroxime
Ceftriaxone
Cefotaxime

50
Q

Example of a beta-lactamase inhibitor?

A

Co-amoxiclav (amoxicillin-clavulanate)

51
Q

What can treat MRSA?

A

Vancomyocin

52
Q

Examples of macrolide abx + uses

A

Clarithromycin
Erythromycin

gram positive and atypical pneumonia

53
Q

When is clindamycin used?

A

gram positive
cellulitis (penicillin)
necrotising fasciitis

54
Q

When are tetracyclines used?

A

e.g. doxycycline
covers staph aureus and strep
doxycycline: anti malaria

55
Q

What is gentamicin used for?

an aminoglycoside

A

can be ototoxic and nephrotoxic so requires strict monitoring
used in UTIs and infective endocarditis

56
Q

What is ciprofloxacin used for?

A

can be used for gram neg
UTIs
intra-abdo infections

side effects: lowering of seizure threshold, bad in AAA

57
Q

What abx for UTIs?

A

Trimethoprim: not in pregnancy as targets folate synthesis
Nitrofurantoin

58
Q

Examples of abx that affect nucleic acid synthesis

A

Rifampicin
Metronidazole
Fluroquinolones (cipro)

59
Q

What abx inhibit folate synthesis?

A

Trimethoprine
Co-trimoxazole

60
Q

What abx affect protein synthesis?

A

aminoglycosides (gentamicin)
Tetracyclines (doxycycline)
Macrolides (erythromycin)

61
Q

What is C.difficile?

A

gram positive anaerobic bacilli

62
Q

What is C.diff infection associated with?

A

associated with repeated use of antibiotics, proton-pump inhibitors (e.g., omeprazole) and healthcare settings

63
Q

Which abx are associated with (lead to) c.diff?

A

Clindamycin
Ciprofloxacin (and other fluoroquinolones)
Cephalosporins
Carbapenems (e.g., meropenem)

64
Q

How does a c.diff inection present?

A

diarrhoea, nausea and abdominal pain.

65
Q

How is a c.diff infection treated?

A

Oral vancomycin (first-line)
Oral fidaxomicin (second-line)

66
Q

What is dysentery?

A

An inflammatory disorder of the GI tract often associated with
- blood and pus in the faeces
- pain
- fever
- abdominal cramp

usually resulting from disease of the large intestine

67
Q

Symptoms of gastroenteritis

A

nausea
vomiting
diarrhoea
abdo discomfort

68
Q

What viruses can cause diarrhoea?

A

norovirus
rotavirus

69
Q

What bacteria can cause bloody mucoid diarrhoea?

A

Clostridium difficile
E.Coli (EIEC, EHEC)
Campylobacter
Salmonella
Shigella

70
Q

What can cause diarrhoea in a recent traveller?

A

Giardia
Cryptosporidium
Cyclospora

71
Q

What are 2 food-borne diarrhoeal causes?

A

Campylobacter
Salmonella

72
Q

What causes colonic or dysenteric diarrhoea?

bloody stools, fever, abdominal cramps, and tenesmus.

A

Shigella

73
Q

What is HIV postive?

A

infected with the human immunodeficiency virus (HIV)

74
Q

When does AIDs occur?

A

Acquired immunodeficiency syndrome (AIDS) occurs when HIV is not treated, the disease progresses, and the person becomes immunocompromised.
Immunodeficiency leads to opportunistic infections and AIDS-defining illnesses.

75
Q

What key populations are affected by HIV?

A

commercial sex workers and their clients
gay men and other men who have sex with men
people who inject drugs
transgender people

Most new cases in sub-saharan africa

76
Q

What is HIV-1 infection associated with?

A

progressive decrease in CD4 T-cell count and an increase in viral load leading to clinical AIDS

77
Q

What is HIV-2 associated with?

A

more indolent course
largely limited to West Africa

78
Q

How can HIV be transmitted?

A

blood
blood products
sexual fluids
other fluids containing blood
breast milk

79
Q

How are most individuals infected with HIV?

A

sexual contact
before birth or during delivery
during breastfeeding
when sharing contaminated needles and syringes

80
Q

How does HIV replicate?

A

Virus gains entry to cells by attaching to CD4 receptors of T-helper cells
Reverse transcriptase enzyme allows DNA copy from RNA
Virus integrated into cell DNA and replicated

81
Q

What type of virus is HIV?

A

RNA retrovirus

82
Q

What are the risk factors for HIV?

A

people who inject drugs
gay men and other men who have sex with men
commercial sex worker
transgender women
unprotected receptive intercourse
percutaneous needle stick injury
racial and ethnic minorities
high maternal viral load (mother to child transmission)

83
Q

What are some symptoms of HIV?

immunodeficiency

A

fevers and night sweats
weight loss
skin rashes and post-inflammatory scars
oral ulcers
diarrhoea
weight loss
changes in mental status
generalised lymphadenopathy

84
Q

How does the 4th gen HIV screening test work?

A

fourth-generation laboratory test for HIV checks for antibodies to HIV and the p24 antigen.
It has a window period of 45 days, meaning it can take up to 45 days after exposure to the virus for the test to turn positive.

85
Q

What investigations should be run for HIV?

A

HIV enzyme-linked immunosorbent assay (ELISA): positive
HIV rapid test: positive
HIV PCR: positive
Serum p24 antigen: positive
CD4 count
Genotypic resistance testing
Hepatitis B and C screening

86
Q

What is an AIDS defining illness?

A

AIDS defining illnesses associated with end-stage HIV
(CD4 count has dropped to a level that allows for unusual opportunistic infections and malignancies to appear)

87
Q

What are some examples of AIDS defining illnesses?

A
  • Kaposi’s sarcoma
  • Pneumocystis jirovecii pneumonia (PCP)
  • Cytomegalovirus infection
  • Candidiasis (oesophageal or bronchial)
  • Lymphomas
  • Tuberculosis
88
Q

What are the classes of antiretroviral therapy medications?

A

Protease inhibitors (PI)
Integrase inhibitors (II)
Nucleoside reverse transcriptase inhibitors (NRTI)
Non-nucleoside reverse transcriptase inhibitors (NNRTI)
Entry inhibitors (EI)

88
Q

How can HIV be monitored?

A

CD4 count (<200ml more at risk of opportunistic infection)
HIV viral load

89
Q

What is the usual starting ART for HIV?

A

two NRTIs (e.g., tenofovir plus emtricitabine) plus a third agent (e.g., bictegravir)

90
Q

What does treatment in HIV aim for?

A

Treatment aims to achieve a normal CD4 count and undetectable viral load

91
Q

Apart from ARTs, what additional management is offered to HIV patients?

A
  • Prophylactic co-trimoxazole is given to all HIV positive patients with a CD4 count under 200/mm3 to protect against pneumocystis jirovecii pneumonia (PCP)
  • Vaccinations (not live)
  • Yearly cervical smears
  • CVD risk management
92
Q

How can reproductive health be maintained in HIV?

A

Correct use of condoms protects against spreading HIV.
Effective treatment combined with an undetectable viral load appears to prevent the spread of HIV, even during unprotected sex

93
Q

What is used in post-exposure prophylaxis for HIV?

A
  • emtricitabine/tenofovir (Truvada) and raltegravir for 28 days. (ARTs)
  • given within 72 hours
94
Q

What is used as pre-exposure prophylaxis in HIV?

A

emtricitabine/tenofovir (Truvada).

95
Q

What are the basic BHIVA guidelines for reducing HIV transmission in pregnancy?

A

Viral load depends on method of brith
- Under 50: normal vaginal
- Over 50: consider pre-labour C section
- Over 400: pre-labour C section
IV zidovudine is given as an infusion during labour and delivery if the viral load is unknown or above 1000 copies/ml

96
Q

What prophylaxis can be given to babies at risk of HIV from mother?

A
  • Low-risk babies (mother’s viral load is under 50 copies per ml) are given zidovudine for 2-4 weeks
  • High-risk babies are given zidovudine, lamivudine and nevirapine for four weeks
97
Q

What bacteria causes chlamydia?

A
  • Chlamydia trachomatis is a gram-negative bacteria
  • Intracellular organism
98
Q

How is chlamydia diagnosed?

A

Nucleic acid amplification tests from swab

99
Q

How is chlamydia treated?

A
  • First line doxycycline 100mg a day
  • In pregnancy and breastfeeding: Azithromycin (or other macrolides)
100
Q

What bacteria causes gonorrhoea?

A

Neisseria gonorrhoeae is a gram-negative diplococcus bacteria.

101
Q

Where does gonorrhoea infect and how does it spread?

A

It infects mucous membranes with a columnar epithelium
- endocervix in women
- urethra
- rectum
- conjunctiva
- pharynx
It spreads via contact with mucous secretions from infected areas

102
Q

What symptoms may be present in gonorrhoea?

A
  • Odourless purulent discharge, possibly green or yellow
  • Dysuria
  • Pelvic pain
  • testicular pain
103
Q

How is gonorrhoea diagnosed?

A

Nucleic acid amplification testing (NAAT) is used to detect the RNA or DNA of gonorrhoea.
Genital infection can be diagnosed with endocervical, vulvovaginal or urethral swabs, or in a first-catch urine sample

104
Q

What is the management for gonorrhoea?

A

A single dose of intramuscular ceftriaxone 1g if the sensitivities are NOT known
A single dose of oral ciprofloxacin 500mg if the sensitivities ARE known

105
Q

What bacteria causes syphilis?

A

Treponema pallidum
Spirochete (spiral-shaped bacteria)

106
Q

How does syphilis enter body?

A

gets in through skin or mucous membranes, replicates and then disseminates throughout the body

107
Q

How can syphilis be transmitted?

A

Oral, vaginal or anal sex involving direct contact with an infected area
Vertical transmission from mother to baby during pregnancy
Intravenous drug use
Blood transfusions and other transplants

108
Q

How does primary syphilis present?

A

A painless genital ulcer (chancre). This tends to resolve over 3-8 weeks.
Local lymphadenopathy

109
Q

What can be used to screen for syphilis?

A

Antibody testing for antibodies to the T. pallidum bacteria

110
Q

How is syphilis treated?

A

single deep IM dose of benzathine benzylpenicillin

111
Q
A

Phase 2a (14 decks)

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