Medical Microbiology Flashcards

0
Q

Sero groups of N meningitidis

A

A, B, C, W135

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1
Q

Morphology of N meningitidis

A

Gram negative diplococci

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2
Q

Up to half N meningitidis membrane made up of

A

Lipo-oligosaccharide (containing endotoxin Lipid A)

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3
Q

Predisposing factors for N meningitidis

A
Asplenia ( anatomical or functional)
Complement deficiency (C8/C9)
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4
Q

Most common sporadic serogroup for N meningitidis in WP

A

Serogroup B

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5
Q

What does the lipo-oligosaccharide do in N meningitidis

A

Activates macrophages - TNF released = shock mediator in septicaemia

Alters permeability of BBB = CNS invasion

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6
Q

Who gets chemoprophyaxis in N meningitidis

A

Direct contacts

Mouth to mouth resus

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7
Q

What drugs are used as chemoprophyaxis in N meningitidis

A

Ceftriaxone
Ciprofloxacin
Rifampicin

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8
Q

What is factor X and where is it found

A

Haemin

Found in whole blood

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9
Q

What is factor V and where is it found

A

NAD

Found inside RBC

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10
Q

How is factor V created in petridish

A

Blood is heated = chocolate blood agar
Or
Organisms added to blood eg. Staphylococci. H influenzae grows on edges of colonies = satellitism

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11
Q

What is the typical pathogenesis of untypeable H influenzae

A

Contiguous spread from nasopharynx

  • conjunctivitis
  • otitis media
  • sinusitis
  • acute exacerbations of chronic bronchitis
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12
Q

What is pathogenesis of type b H influenzae

A

Spread beyond resp tract -> bacteraemia -> metastatic infection

  • acute meningitis
  • acute epiglottitis
  • pneumonia
  • septic arthritis
  • cellulitis
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13
Q

Rx of H influenzae

A

3rd gen cephalosporin

If non invasive = oral co-amoxiclav

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14
Q

Lab diagnosis of H influenzae

A

MC&S

Latex agglutination - PRP Ag

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15
Q

Vaccine type given to those under 2 years for h influenza

A

Conjugate vaccine

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16
Q

What stain doesH influenzae have

A

Gram negative coccobacilli

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17
Q

What is the morphology of strep pneumonia

A

Gram positive lanceolate diplococci

Alpha haemolysis

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18
Q

What are the predisposing factors for strep pneumonia

A
Asplenia
Overcrowding 
Viral URTI
Diabetes
Fluid in alveoli eg CCF, aspiration
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19
Q

What is the lab diagnosis of s pneumonia

A

Gram stain tissue

NB culture in pneumonia as bacteraemia is common

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20
Q

Rx of s pneumonia

A

IV penicillin except in meningitis must give third gen cephalosporin

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21
Q

Type of vaccine for s pneumonia

A

Protein conjugate (polyvalent) pneumococcal vaccine

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22
Q

Who gets s pneumonia vaccine

A

Splenectomy

? Those with predisposing factors

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23
Q

Do you isolate s pneumonia pts and why

A

No. Infection is most often endogenous

24
Q

Complication of pneumonia in s pneumonia infection

A

Pleural effusion

Pericarditis = rare

25
Q

Pathologies caused by s pneumonia

A

Pneumonia, meningitis, otitis media, sinusitis, endocarditis, arthritis, peritonitis

26
Q

Gram stain of E. coli

A

Gram negative bacilli

27
Q

Types of surface Ag on E. coli

A

O - LPS
K - polysaccharide capsule
H - flagella

28
Q

Gram stain of listeria monocytogenes

A

Small gram positive bacilli

29
Q

What is the appearance on culture of l monocytogenes

A

Translucent grey/white colonies

B haemolysis on blood agar

30
Q

L monocytogenes grows in presence of what..and what does it hydrolyse

A

Bile

Aesculin

31
Q

Who is at risk for l monocytogenes infection

A

Pregnant
Neonate
Elderly
Immunocomprimsed

32
Q

Treatment of l monocytogenes

A

High dose ampicillin or penicillin

NOTE resistant to cephalosporins

33
Q

Gram stain of strep agalactiae

A

Gram positive cocci

34
Q

Haemolysis seen on culture for s agalactiae

A

Beta haemolysis (less than group A strep)

35
Q

What determines s agalactiae serotype

A

Capsular polysaccharide

Surface protein

36
Q

Rx of s agalactiae

A

Penicillin

37
Q

When is s agalactiae most commonly transmitted

A

During birth

Days following birth

38
Q

Rx of s agalactiae

A

Penicillin

39
Q

Predisposing factors for cryptococcus neoformans

A

Immunocomprimsed pts

40
Q

Where is c neoformans found

A

Soil mixed w pigeon faeces

41
Q

Lab diagnosis of c neoformans

A

CSF analysis
Microscopy - India ink
Culture
Latex agglutination

42
Q

Rx of c neoformans

A

Amphotericin B followed by fluconazole

NB no cure in AIDS

43
Q

Common sites of spread of c neoformans in immunocomprimsed pts

A

CNS
Bone
Skin

44
Q

Orgs that can cause genial ulcer and Rx

A

Treponema pallidum - penicillin
Chlmydia trachomatis - tetracycline
HSV - acyclovir
Haemophilus ducreyi - ceftriaxone

45
Q

Effect of antibiotics of CSF findings

A
  • negative cultures
  • glucose normalizes
  • gram stain negative
  • white cell count decreases
  • protein decreases
46
Q

CSF test that shouldn’t be done routinely (no effect on management)

A
  • bacterial latex antigen test
  • lactate
  • chloride
  • adenosine deaminase
47
Q

Which parasite causes primary amoebic meningoenceohalitis?

A

Naegleria fowleri

48
Q

Possible reasons for candida infection

A
  • immune system is compromised
  • normal flora disturbed by antibiotics
  • trauma
49
Q

Opportunistic organisms

A
  • cryptococcus neoformans
  • pneumocystis jiroveci
  • cryptosporidium
  • Isospora
  • herpes simplex
50
Q

Complications of acute bacterial meningitis in infants

A
  • focal neurological deficit
  • hearing loss
  • blindness
  • intellectual disability
  • seizures
  • hydrocephalus
51
Q

Antibiotics used as prophylaxis in meningococcal meningitis

A
  • ceftriaxone
  • ciprofloxacin
  • rifampicin
52
Q

Organisms causing vaginal discharge

A
  • neisseria gonorrhoea
  • chlamydia trachomatis
  • trichomonas vaginalis
  • Candida albicans
53
Q

Anaerobes causing infection in diabetic foo

A

Bacteroides fragilis

54
Q

Where can anaerobes be found as normal flora?

A
  • colon
  • oral cavity
  • naso pharynx
  • lower urogenital tract
55
Q

Predisposing factors for anaerobes infection

A
  • breach in mucosal or cutaneous barrier

- reduced oxygen tension in tissue

56
Q

Antibiotics to treat anaerobic infection

A
  • metronidazole
  • clindamycin
  • penicillin
57
Q

4 infections commonly caused by anaerobes

A
  • peritonsillar abscess
  • tubo-ovarian abscess
  • dental infections
  • peritonitis
  • perirectal abscess
  • lung abscess
  • aspiration pneumonia
58
Q

Fungal infections to Which diabetics are prone

A
  • candidiasis

- mucormycosis (nasal sinuses)