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2.2 Microbiology > Celine - Neisseria > Flashcards

Celine - Neisseria Flashcards

1
Q

What type of bacteria are Neisseria and Moraxella

A

Gram Negative Cocci

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2
Q

Write about the genus Neisseria
(2)

A

11 species known to colonise humans

Most are normal flora of nasopharynx

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3
Q

What are the 2 only species of Neisseria of clinical significance

A

N. gonorrhoeae
N. meningitidis

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4
Q

What are the 4 species of Neisseria which exist as normal flora commensals

A

N. lactamica
N. sicca
N. flavescens
N. elongata

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5
Q

What kind of infections does Neisseria gonorrhoeae cause?
(4)

A

Infections have high prevalence and low mortality
Unlike other Neisseria species these are not part of normal flora
Transmission by sexual contact - its a STI
Can cause acute pyogenic infection of the epithelium of various mucosal surfaces

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6
Q

What are the three types of Neisseria gonorrhoeae infections

A

Asymptomatic
Symptomatic uncomplicated
Symptomatic complicated infections

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7
Q

What is an asymptomatic N. gonorrhoeae infection?

A

Reservoir for transmission

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8
Q

What is a symptomatic uncomplicated N. gonorrhoeae infection?

A

Restricted to mucosal sites

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9
Q

What is symptomatic complicated N. gonorrhoeae infections?

A

Invasive and disseminated infection - rare

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10
Q

Why are STIs so important

A

Most common group of identifiable infectious diseases in many countries especially among the ages of 15-50

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11
Q

What are the four most common STI

A

Trichomoniasis
Chlamydia
Gonorrhoea
Syphilis

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12
Q

Comment on the stats of STIs

A

The incidence of STIs has continued to rise

Genital Warts HPV has decreased

Chlamydia has been on the increase

Gonorrhoea on the rise but startig to plateaux

Herpes simplex virus was on the rise but starting to plateua

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13
Q

Comment on the stats for Gonorrhoea

A

Second most common STI in Ireland
Increased by 2.3% in 2021
90% of notifications are male
5:1 male:female ratio
78% are gbMSM -> often in nonurethral sites
Target health promotion and screening in MSM

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14
Q

What were the 2021 stats for covid?

A

N. gonorrhoeae increased by 2.3%

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15
Q

Comment on the importance of N. Gonorrhoeae lab investigation

A

STI in gbMSM

Often found in nonurethral sites

Gonorrhoea undiagnosed if only looking at urethral screening

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16
Q

Comment on N. Gonorrhoea infections in males
(5)

A

Primary site of infections include urethra, pharyngeal and rectal

55-100% are asymptomatic

45% are symptomatic

Causes acute urethritis with yellow purulent discharge and dysuria (pain on micturition), 1-14 days after infection-easy to diagnose

Anorectal and oropharyngeal in gbMSM

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17
Q

What are the complications of N. gonorrhoea infections in males?

A

Prostatitis and epididymitis occur if untreated

Gonococcaemia and joint disease - very rare

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18
Q

Comment on N. Gonorrhoea in females
(4)

A

Primary site of infection is the cervix but also anorectal

90% are asymptomatic and remain undiagnosed reservoir for infection

Symptomatic infection not common

Cervix primary site -> vaginal discharge, burning and frequency and menstrual abnormalities, fever and pain

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19
Q

What are the complications of N. gonorrhoea?
(3)

A

20% of cases extend to uterus leading to pelvic inflammatory disease (PID) - infertility or ectopic pregnancies

Gonococcaemia and joint disease may occur - rare

Transmit to infants - ophthalmia neonatorum - infected conjunctiva

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20
Q

What are the virulence factors of N. gonorrhoeae?
(7)

A

Pili
Opa protein
Iron binding proteins
IgA protease
Por protein
Lipooligosaccharide
No capsule

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21
Q

How do the pili act as virulence factors in N. gonorrhoeae?

A

They adhere to nonciliated mucosal epithelium
Antigenic variation - immune evasion

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22
Q

What does the Opa protein do?

A

Assist in epithelium binding
Assist in antigenic variation and allow for immune evasion

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23
Q

What does iron binding protein do?

A

Facilitates multiplication and colonisation

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24
Q

What does IgA protease do?

A

This cleaves IgA1

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25
What does Por protein do?
Invasin Forms pores
26
What does Lipooligosaccharide do?
LOS is an endotoxin which causes tissue damage
27
What virulence factor does N. gonorrhoeae not have?
No capsule
28
Write about N. meningitidis (6)
Infections have low prevalence and high mortality Normal flora in 10-15% of people - colonise the posterior nasopharynx carriers Carriers can transmit disease to non-immune hosts Transmission by respiratory droplets - aerosols Close and prolonged contact - nurseries, schools, kissing, sneezing Infection may be random or outbreaks
29
What kind of people does N. meningitidis infect? (2)
Hosts that are lacking antibodies (to capsule) Deficient in complement components (C5-C8)
30
What kind of infections does N. Meningitidis cause (6)
BSI Meningitis Meningococcemia Invasive meningococcal disease (IMD) 2 presentations Acute meningitis Meningococcemia
31
Comment on the BSI caused by N. meningitidis
Following aspiration bacteria attach to epithelial cells of the nasopharyngeal mucosa, cross mucosal barrier, enter the bloodstream Invasive infection
32
How does N. Meningitidis cause meningitis? (3)
Bacteria enters the CNS causing meningitis May cause invasive meningococcal disease High mortality
33
What happens when N. meningitis enters the BS other than a BSI (3)
5-20% enter BS without meningitis-meningococcaemia Associated with invasive fulminant infection More damaging and dangerous condition
34
What is IMD
Invasive meningococcal disease
35
What is the characteristic sign of meningococcemia
Haemorrhagic lesions
36
What is Meningitis? (4)
Causes fever, headache, stiff neck and petechial rash (75% septic cases) Even when disease diagnosed early and treatment started 5-15% of patients die within 24-48 hours of onset Brain damage, hearing loss or learning disability in 10-15% of survivors
37
What is meningococcemia? (4)
Causes fever, purpuric lesion, multi-system involvement Disseminated Intravascular Coagulation Haemorrhaging and destruction of adrenals - Waterhouse-Friderichsen syndrome 50% of untreated patients die
38
What is a tell tale sign of meningitis
Meningococcal rash
39
What is a tell tale sign of meningococcemia?
Purpuric skin lesions
40
Comment on the incidence of N. meningitidis (5)
Most common form of bacterial meningitis in Ireland Incidence highest in babies and young adolescents 50% of cases in first year of life All invasive meningococcal disease caused by N. meningitidis serogroups A, B, C, Y, W Serogroup B most common
41
What vaccines are there for meningitis and when were they introduced? (2)
In 2000 the MenC vaccine was introduced In 2016 the MenB conjugate vaccine was introduced
42
Comment on the stats behind invasive meningococcal disease in Ireland (5)
Marked downward trend in IMD with the intro of MenC Small increase in 2012 2015 MenC booster introduced MenB introduced in 2016 Increase of other groups such as W and Y now
43
What are the six virulence factors of N. meningitidis
Fimbriae Capsule Iron acquisition Porin sIgA protease Lipooligosaccharide
44
What do fimbriae do?
Attach to nonciliated epithelial cells Antigenic switching - allows for immune evasion
45
What does the capsule do for N. meningitidis
Prominent antiphagocytic polysaccharide Immune evasion
46
What is iron acquisition for
Multiplication
47
What are porins for
Tissue invasion
48
What is sIgA protease for
Weaken mucosal immunity
49
What is LOS
Lipooligosaccharide Endotoxin Major toxin Tissue damage
50
What clinical specimens are common in N. gonorrhoeae
Genital - urethral exudates, cervical swab Extra-genital e.g. rectal swabs, pharyngeal swabs Joint fluid - occasionally
51
What clinical specimens is N. meningitidis common in
Invasive infection - CSF, blood culture, skin scrapings Carriage - nasopharyngeal swab
52
Comment on the transport of Neisseria to the lab (4)
Neisseria is fastidious It is sensitive to drying and temperature variation Need to use transport media for survival Transport to lab without delay
53
What is done with N. gonorrhoeae on day 1 (5)
Direct specimen microscopy Isolation
54
Write about the direct specimen - microscopy of N. gonorrhoea
Gram stain smear of urethral discharge Gram-negative kidney-bean intracellular diplococci in pus cells 90% sensitivity and specificity for symptomatic male 30% sensitivity for women and asymptomatic male
55
How does N. gonorrhoeae appear in direct specimen microscopy
Gram-negative kidney-bean intracellular diplococci
56
What is done with N. meningitidis on day 1 (5)
Direct specimen microscopy White cell count Biochemical markers Direct specimen - antigen detection Isolation
57
Write about the direct specimen microscopy of N. meningitidis
Gram stain on CSF or skin scrapings Gram negative kidney bean intracellular diplococci in polymorphonuclear leukocytes
58
How does N. meningitidis appear on direct microscopy gram stain
Gram negative kidney bean intracellular diplococci in polymorphonuclear leukocytes
59
Write about using a white cell count to identify N. meningitidis
Count the number of white and red cells in CSF White cell differential count -> polymorphs (bacterial) vs mononuclear (viral/TB)
60
Write about using biochemical markers in day 1 ID of N. meningitidis
Increase in protein Decrease in glucose
61
Write about the direct specimen antigen detection on day 1 for N. meningitidis (6)
Rapid identification of serious invasive infection Direct latex agglutination for N. meningitidis Latex beads coated with antisera for gpB, C, Y and W Detect group antigen direct in CSF Rapid, sensitive and specific Result available before on Day 1 before culture
62
In direct latex agglutination for N. Meningitidis what are the beads coated with
Antisera for gpB, C, Y and W
63
Write about growth characteristics (2)
Pathogenic species fastidious, require blood or serum as well as growth factors (iron, haemin) to grow They are capnophilic they only grow in 5-10% CO2, 37 degrees, 24-48 hour
64
What is Neisseria put up on on day 1?
Blood agar and chocolate agar, chocolate broth
65
What is Neisseria gonorrhoeae put up on on day 1? (4)
Its more fastidious so it requires enriched agar but also contaminated mucosal sites - enriched selective media (add antibiotic cocktail for selectivity) Thayer-Martin medium New York City medium You should warm plates before inoculating
66
What is GC (New York City)?
GC is enriched by lysed blood and yeast extract and antibiotics For isolation of N. gonorrhoeae
67
How should you incubate your Neisseria agar
Incubate all at 5-10% CO2, 37 degrees Celsius, 24-48 hours
68
What are the basic characteristics of Neisseria? (3)
Gram-negative kidney bean diplococci Oxidase positive Catalase positive
69
How do you remember the basic characteristics
GONOCC Gram negative diplococci, kidney bean shaped Obligate aerobes Nonmotile Oxidase positive Catalase positive Capnophilic - prefer increased level of CO2 (5-10%)
70
What testing is done on day 2 for Neisseria
Biochemical ID tests (TAXO sugars) Automation
71
Write about the biochemical ID/ TAXO sugars test for Neisseria
Carbohydrate utilisation tests - discriminatory test Neisseria use carbohydrates oxidatively - not fermentation tests Test ability to oxidise glucose, maltose, lactose and sucrose Media e.g. Choc or GC agar minus antibiotics Lawn inoculum and apply Taxo sugar discs Incubate overnight in 5-10% CO2 Add phenol red indicator - yellow = positive oxidation reaction
72
Write about the automated confirmatory tests for Neisseria (2)
Maldi-TOF-mass spectroscopy - ID bacteria based on protein profile Vitek-NH-biochemical profile
73
Write about Neisseria meningitis confirmation using molecular detection (3)
N. meningitis - CSF sent to Irish Meningitis and Sepsis Reference Lab in Temple Street Hospital Confirm by PCR - performed in addition to culture diagnostic lab 50% of meningitis cause in Ireland confirmed by PCR along-culture negative due to immediate antibiotic treatment
74
Write about Neisseria gonorrhoeae confirmation using molecular detection (3)
Commercial PCR tests for combined detection of N. gonorrhoeae and Chlamydia Detect detection in clinical specimen performed on Day 1 - gold standard test method - no conventional culture MDR N. gonorrhoeae emerging - representative culture and antimicrobial susceptibility testing required

2.2 Microbiology (60 decks)

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