Celine - Neisseria Flashcards
What type of bacteria are Neisseria and Moraxella
Gram Negative Cocci
Write about the genus Neisseria
(2)
11 species known to colonise humans
Most are normal flora of nasopharynx
What are the 2 only species of Neisseria of clinical significance
N. gonorrhoeae
N. meningitidis
What are the 4 species of Neisseria which exist as normal flora commensals
N. lactamica
N. sicca
N. flavescens
N. elongata
What kind of infections does Neisseria gonorrhoeae cause?
(4)
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
What are the three types of Neisseria gonorrhoeae infections
Asymptomatic
Symptomatic uncomplicated
Symptomatic complicated infections
What is an asymptomatic N. gonorrhoeae infection?
Reservoir for transmission
What is a symptomatic uncomplicated N. gonorrhoeae infection?
Restricted to mucosal sites
What is symptomatic complicated N. gonorrhoeae infections?
Invasive and disseminated infection - rare
Why are STIs so important
Most common group of identifiable infectious diseases in many countries especially among the ages of 15-50
What are the four most common STI
Trichomoniasis
Chlamydia
Gonorrhoea
Syphilis
Comment on the stats of STIs
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
Comment on the stats for Gonorrhoea
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
What were the 2021 stats for covid?
N. gonorrhoeae increased by 2.3%
Comment on the importance of N. Gonorrhoeae lab investigation
STI in gbMSM
Often found in nonurethral sites
Gonorrhoea undiagnosed if only looking at urethral screening
Comment on N. Gonorrhoea infections in males
(5)
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
What are the complications of N. gonorrhoea infections in males?
Prostatitis and epididymitis occur if untreated
Gonococcaemia and joint disease - very rare
Comment on N. Gonorrhoea in females
(4)
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
What are the complications of N. gonorrhoea?
(3)
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
What are the virulence factors of N. gonorrhoeae?
(7)
Pili
Opa protein
Iron binding proteins
IgA protease
Por protein
Lipooligosaccharide
No capsule
How do the pili act as virulence factors in N. gonorrhoeae?
They adhere to nonciliated mucosal epithelium
Antigenic variation - immune evasion
What does the Opa protein do?
Assist in epithelium binding
Assist in antigenic variation and allow for immune evasion
What does iron binding protein do?
Facilitates multiplication and colonisation
What does IgA protease do?
This cleaves IgA1
What does Por protein do?
Invasin
Forms pores
What does Lipooligosaccharide do?
LOS is an endotoxin which causes tissue damage
What virulence factor does N. gonorrhoeae not have?
No capsule
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
What kind of people does N. meningitidis infect?
(2)
Hosts that are lacking antibodies (to capsule)
Deficient in complement components (C5-C8)
What kind of infections does N. Meningitidis cause
(6)
BSI
Meningitis
Meningococcemia
Invasive meningococcal disease (IMD) 2 presentations
Acute meningitis
Meningococcemia
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
How does N. Meningitidis cause meningitis?
(3)
Bacteria enters the CNS causing meningitis
May cause invasive meningococcal disease
High mortality
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
What is IMD
Invasive meningococcal disease
What is the characteristic sign of meningococcemia
Haemorrhagic lesions
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
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
What is a tell tale sign of meningitis
Meningococcal rash
What is a tell tale sign of meningococcemia?
Purpuric skin lesions
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
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
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
What are the six virulence factors of N. meningitidis
Fimbriae
Capsule
Iron acquisition
Porin
sIgA protease
Lipooligosaccharide
What do fimbriae do?
Attach to nonciliated epithelial cells
Antigenic switching - allows for immune evasion
What does the capsule do for N. meningitidis
Prominent antiphagocytic polysaccharide
Immune evasion
What is iron acquisition for
Multiplication
What are porins for
Tissue invasion
What is sIgA protease for
Weaken mucosal immunity
What is LOS
Lipooligosaccharide
Endotoxin
Major toxin
Tissue damage
What clinical specimens are common in N. gonorrhoeae
Genital - urethral exudates, cervical swab
Extra-genital e.g. rectal swabs, pharyngeal swabs
Joint fluid - occasionally
What clinical specimens is N. meningitidis common in
Invasive infection - CSF, blood culture, skin scrapings
Carriage - nasopharyngeal swab
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
What is done with N. gonorrhoeae on day 1
(5)
Direct specimen microscopy
Isolation
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
How does N. gonorrhoeae appear in direct specimen microscopy
Gram-negative kidney-bean intracellular diplococci
What is done with N. meningitidis on day 1
(5)
Direct specimen microscopy
White cell count
Biochemical markers
Direct specimen - antigen detection
Isolation
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
How does N. meningitidis appear on direct microscopy gram stain
Gram negative kidney bean intracellular diplococci in polymorphonuclear leukocytes
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)
Write about using biochemical markers in day 1 ID of N. meningitidis
Increase in protein
Decrease in glucose
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
In direct latex agglutination for N. Meningitidis what are the beads coated with
Antisera for gpB, C, Y and W
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
What is Neisseria put up on on day 1?
Blood agar and chocolate agar, chocolate broth
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
What is GC (New York City)?
GC is enriched by lysed blood and yeast extract and antibiotics
For isolation of N. gonorrhoeae
How should you incubate your Neisseria agar
Incubate all at 5-10% CO2, 37 degrees Celsius, 24-48 hours
What are the basic characteristics of Neisseria?
(3)
Gram-negative kidney bean diplococci
Oxidase positive
Catalase positive
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%)
What testing is done on day 2 for Neisseria
Biochemical ID tests (TAXO sugars)
Automation
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
Write about the automated confirmatory tests for Neisseria
(2)
Maldi-TOF-mass spectroscopy - ID bacteria based on protein profile
Vitek-NH-biochemical profile
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
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
