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streptococci Flashcards

1
Q

-Streptococci represent a diverse group of gram — organisms
- many normally colonise — membrane
1- prodominent component of ——
2- many of —- virulence
3- However may also invade normally sterile body sites, causing significant —-

A
  • positive
  • mucosal
  • respiratory, gastrointestinal
    and genital tract
  • low
  • disease
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2
Q

streptococci : basic lab features:
1- they are gram – shaped — can either be: —- tr —-
2- Optimal growth media
supplemented with —-
- may cause —- on blood agar
3- catalase is —
4- most are —–

A
  • positive
    -cocci
  • can be chains either long or short or pair ( diplococci )
  • blood
  • haemolytic ( destruction of rbc )
  • negative
  • facultative anaerobes
    (Some are strict (obligate) anaerobes)
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3
Q

classification of systems:
1- based of their actions on —–
2- based on — contained in their cell wall
3- —- classification based on emm gene ( codes for m protein )

A
  • blood containing agar ( haemolytic )
  • antigen ( lance field classification )
  • molecular ( new)
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4
Q

true or false:
Some clinically important streptococci often referred to by both Lancefield group and haemolysis patter

A

true

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5
Q

streptococci:
—- : Reduce Hb and cause a greenish discolouration of blood agar
—- : Lyse blood cells & cause complete clearing of blood agar in the vicinity of their growth
—- : no change in blood agar

A
  • alpha haemolytic
  • beta haemolytic
  • gamma haemolytic
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6
Q

lancefield classification is a — system of grouping streptococci based on specific —- present in their cell wall
groups — of most clinical siginifance
basis of tests:

A
  • serological
  • antigen
  • A-G
  • antibody/anitgen reaction , positive if angulation is detected
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7
Q

clinically important streptococci :

A
  1. Strep. pyogenes (Group A, beta-haemolytic)
  2. Strep. agalactiae (Group B, beta haemolytic)
  3. Other beta-haemolytic streptococci
  4. alpha-haemolytic streptococci
    -“viridans” streptococci
    - Strep. pneumoniae (pneumococcus)
  5. Enterococci (Group D, beta or non-haemolytic)
  6. Peptostreptococcus (anaerobic or non-haemolytic)
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8
Q

-STREPTOCOCCUS PYOGENES are group — and — haemolytic streptococci
- commonly colonise — of children and young adults ( colonisation is —- , influenced by —- and competition from other — in orpharynx)
- among the — prevalent pf human bacterial pathogen
- major cause of:

A
  • A
  • beta
  • propharnyx
  • transients
  • immunity
  • organics
  • most
  • bacterial pharyngitis
    ( in Irish epidemiology the invasive group A strep is notifiable disease )
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9
Q

GROUP A, beta HAEMOLYTIC STREPTOCOCCI: VIRULENCE MECHANISMS
- virulence factors include
1- — components :
—- : resists pahogystocis
—- : peptidoglycan can activate alternative complement system
2- — proteins :
->80 types, mediate attachment to cells, anti-phagocytic
- Major virulence factors – some types associated with greater severity of disease
-the M-like proteins bind —-
3- —- :
* Streptolysin O/S
exotoxins
– ASOT titre
* Hyaluronidase
– Tissue destruction,
allowing spread of
infection
* Leucocidin
* Haemolysins
* Streptokinase
4- —— erthyrogenic exotoxins
- responsible for fever and rash
- protent activators of — ( toxic shock syndrome )
- activate of — to increase secretion of —-
- produced by — and —

A
  • structural
  • capsule
  • cell wall
  • m protein
  • IgG/igM
  • cytolysins
  • pyrogenic
  • immune system
  • T cells
  • pro inflammatory cytokines
  • antigen presenting cells and t lymphocytes
    ( check slide 13 for summary )
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10
Q

clinical infections include :
1- suppuartive infection as:
2- post infectious immune mediated complication as:

A
  • supportive :
    1. Pharyngitis
    2. Scarlet fever
    3. Erysipelas, cellulitis, necrotising fasciitis
    4. Toxic shock syndrome, bloodstream infection
  • post - infectious :
    – Rheumatic fever*
  • May later develop rheumatic heart disease
    – Glomerulonephritis
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11
Q
  • STREPTOCOCCAL PHARYNGITIS:
    1- One of the most common bacterial infections of —-
    2- occasionally due to group —-or —
    3- spread: —- and its facilitated by —
    4- incubation period:
    5- history:
A
  • childhood
  • c or g
  • Person-to-person via droplets (saliva ornasal secretions)
  • Facilitated by overcrowding
  • 2-4 days
  • sore throat , headaches , fever , nausea , vomiting especially in children
    ( on examination:
  • Redness, oedema,
    lymphoid hyperplasia
  • Enlarged tonsils with
    exudate, enlarged
    tender lymph nodes
  • Fever
    lab findings:
  • positive throat culture
  • immunological
    (antibody) response
    (anti-streptolysin O
    titre, ASOT)
    Hyperaemic, enlarged tonsils
    with exudate
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12
Q

complication of STREPTOCOCCAL PHARYNGITIS:
1- suppurative complication:
2- non suppurative (immunoligcal sequele) :
- main reason for antibiotic treatment is to —-

A
  • suppurative:
    – Quinsy – peritonsillar abscess
    – Otitis media
    – Acute mastoiditis
  • non- suppurative :
    – Acute glomerulonephritis
    – Acute rheumatic fever
  • to prevent rheumatic fever
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13
Q

Delayed-type skin reactivity to pyrogenic toxin produced by the
organism —–
—– may also occur following impetigo

A
  • scarletina ( from scarlet fever )
  • pharungitis + fever
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14
Q
  • Impetigo
  • Erysipelas
  • Cellulitis
  • Necrotising fasciitis
    are all under —-
A

skin and soft tissue infection

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15
Q

other serious infection include;
1- streptococcal toxic shock sydrnom which causes inflammation in — followed by —-
- causes production of —
- progresses —-
2- —- infection and mortality reaches —

A
  • soft tissue inflammation
  • followed by pain fever , chills , multi organ failure
  • pyrogenic exotoxin
  • rapidly
  • blood stream
  • 40%
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16
Q

complication : RHEUMATIC
FEVER & GLOMERULONEPHRITIS

A

Post-streptococcal auto-immune complications
* Affect a minority of people who have group A streptococcal infection
* Immune reaction: Development of antibodies to some fraction of the organism
– In rheumatic fever: the antibodies cross-react with cardiac tissue → immune complex deposition on the heart
– In post-streptococcal glomerulonephritis: immune
complexes are deposited on the glomerular basement
membrane
– Molecular mimicry

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17
Q

acute rheunaric fever is associated w — but not —-
- occurs —- weeks later
- symomts include:
-with recover , affected heart valves become —–
- —- required if undergoing procedure
that may put patient at risk of endocarditis
- Diagnosis is based on the ——

A
  • streptococcal pharyngitis
  • streptococcal skin infections
  • 203 weeks
  • joint pain , fever , carditis , may also get neurological involvement (Syndenham’s chorea)
  • thickened and deformed
  • Antibiotic prophylaxis
  • jones criteria
18
Q

acute glomerulonephritis is associated w —- and sometimes with —-
- causes:
- —-
- majority of young patients recover —- but may lead to:

A

-streptococcal pharyngitis
-streptococcal skin infections
- oedema , puffy face , swollen extremities due to sodium and water retention
- hypertension w albumin and blood in urine
- competly may lead to:
* However, may lead to permanent renal damage
* May warrant lifelong dialysis or renal transplantation
* Or may be fatal

19
Q

STREPTOCOCCUS AGALACTIAE:
- in group —
- – haemolytic streptococci
- colonises the — and —
- —– % women intermittent carry S. agalactiae in vagina
- may be carried in —-
- important cause of neonatal sepsis:

A
  • b
  • b
  • lower gi and gu tract
  • 10-40%
  • throat
  • Neonatal colonization usually occurs via the mother’s
    genital tract
  • Risk factors:
  • Maternal colonisation
  • Premature delivery / Premature rupture of membranes
  • Prolonged labour
  • Low birth rate
  • Intra-partum fever
20
Q

GROUP B -HAEMOLYTIC STREPTOCOCCI:
VIRULENCE MECHANISMS
1- —- polysacride:
- different — based on capsular polysaccharides
2- types —– most commonly associated w colonisation and disease
3- —-
4- —
5 — proteins as–

A
  • capsule
  • serotypes
  • la, III, v
  • haemolysins
  • hyalurindase
  • surface proteins - adhesins
21
Q

other b-haemolytic streptococci :
- can cause similar disses as — but without —- complications
1- group c streptococci :
2- group g streptocci :

A
  • group a
  • immunilogical
  • group c:
  • Puerperal fever
  • Tonsillitis
  • Wound sepsis
  • group g:
  • Upper respiratory tract infections
  • Endocarditis
22
Q

A.“viridans” streptococci
B. Streptococcus pneumoniae
(‘pneumococcus’)
are both under —-

A

alpha-HAEMOLYTIC STREPTOCOCCI

23
Q

viridian streptococci:
1- are found in —
2- most lack — exception for s.bovis in group d
3- clinical infection includes several associations with —- and —
- and its invasive disease often related to breech in —
- — and —- are the commonest viridian strep has — and infective —-
4- —- for dental caries
5- — purulent infections as brain and liver abscesses
5- — linked to colon cancer and infective endocarditis

A
  • Oropharynx, GIT & GU
    tract
  • lance field antigens
  • associated w dental caries and endocarditis
  • mussel surfaces
  • strep sangus and strep mitis
    -tooth biofilm
  • infective endocaditis
  • strep mutans
  • strep. angiosus ( milleri )
  • strep bovis
24
Q

-s peneumiua is type of — haemolytic and gram – in the shape of – in chains or dipoloccocci
- carried in — by :
1—– of healthy adults
2- —- of healthy children
- it has a —- of more than 90 serotypes and – available against some serotypes
- variety of clincial infections

A

-alpha
- +ve
-cocci
- nasopharynx
- 5-10%
-20-40%
- vaccines
(info: Gram-positive diplococci, i.e.
Pneumococcus
(Humphreys, Willatts & Vincent)
CHEKC SLIDE 32 SOOO IMPORTANT )

25
Q

pneumococcal pneumonia:
- symptoms include:
- classically —> — pneumonia and may cause — especially in elderly
- complication include :
- —- a major predisposing factor

A
  • Symptoms:
  • Pleuritic chest pain
  • Shortness of breath
  • Purulent sputum
  • classically —> lobar
  • may cause bronchopneumonia
    • Complications:
  • Parapneumonic effusion
  • Empyema / Lung abscess
  • Bacteraemia
  • influenza
26
Q

—- is a common
cause of acute infection of the
paranasal sinuses and ear and it usually preceded by —- infection
- otitis media usually affects —
- sinusitis affects —

A

s.peneumoniae
- upper respiratory tract infection
- young children
- all ages

27
Q

-how does meningitis get to the central nervous system ?
1- during a —
2- —– infection
3- —- infection
4- after —-
- the BSI/bacteramia 25-30% of patients w —— and it may accompany — it — occurs w cases of sinusitis or otitis media

A
  • bacteriemia
  • chronic ear
    -sinus
  • after head
  • penumococcal pneumonia
  • meningitis
  • rarely
27
Q

enterococci:
1- has — species and —- and — are the most common
2- they are previously classified as —
3- —– usually low virulence
4- are facultative —-
5- their hemolytic patterns —
6- grow in the presence of —
7- — resistance is common

A

-18
- E. faecium and E facecalis
- group d streptococci
- bowel flora
- anaerobes
- varies ( alpha or beta)
- bile salts ( grow on macconket agar)
- vancomycin
CHECK SLIDE 37 SOOSOSOSO IMPORTANT

28
Q

1-The at risk patients of enterococci infections are:
2- type of infections include :

A

At-Risk Patients:
* Recent surgery
* Underlying disease
* Malignancy
* Burns or trauma
* Recent antibiotics
* cephalosporins or
aminoglycosides
* Prolonged hospitalization
* Especially ICU
Types of infection:
1. Urinary tract infection
a) Particularly urinary
catheter-related
2. Endocarditis
3. Bloodstream infection
4. Wound infections
5. Intra-abdominal
infections

29
Q

infective endocarditis has — flow through heart provides a surface for – to attach , this – enters blood usually after — that damages —- example:
- the bacteria attach to —– and —- form

A
  • turbulent
  • bacteria
  • bacteria
  • procedure
  • epithelial barriers as dental extraction, cystoscopy
  • valces and vegetations
    (info: Vegetation on heart valve
    (Slide: A Colour Atlas of Infectious
    Diseases, Emond)
30
Q
  • anaerobic streptoccos peptostrepcoccosu:
    1- more than 25% of anaerobes from —-
    2- colonises —
    3- infection include:
A
  • clinical specimen
  • oral cavity , GI , GU tracts , and skin
  • infections include :
  • Aspiration pneumonia
  • Sinusitis and brain abscess
  • Intra-abdominal abscesses
  • Pelvic infections
31
Q

diagnosis of infection that applies to any infection :
1- —- based on clinical features
2- – sent to a lab based on – of infection as:
3-in the lab:
- — on sterile site sample ( blood , csf , pus)
- culture takes —-
- samples incubated —– and —
- —– for hemolysis
- —– for eneterocci

A
  • clinical suspicion
  • appropriate samples based on site as:
    – Blood (if invasive disease suspected)
    – CSF (meningitis)
    – Urine
    – Throat swab (pharyngitis)
  • gram stain
  • 24-48 hours
  • aerobically and anaerobically
  • blood agar
  • macConkey agar
32
Q

laboratory diagnosis includes:

A
  • Identification
  • Lancefield Grouping
  • Bacitracin susceptibility (GAS)
  • Optochin sensitive (pneumococcus)
  • Bile solubility (enterococci)
  • Serology
  • Detect recent Group A infection in suspected rheumatic
    fever & glomerulonephritis i.e. ASO titres (ASOT)
  • PCR
  • Blood, CSF
  • Urinary antigen (for pneumococcus)
33
Q

s.pyogenes lab diagnosis:
1- its gram —- shaped – in —
2- — haemolytic
3- catalase is —
4- group –
-

A

-+ve
-cocci
- chains
- b
- negative
- a
( info : Group A ß-haemolytic streptococci showing bacitracin
susceptibility (clearing around bacitracin disc)

34
Q

s.penumoniae lab diagnosis:
2- gram — shaped — in – or —-
3- – hameolytic
- catalase is —

A
  • postive
  • cocci
    -chains or diplococci
  • alpha
  • -ve
    (Susceptible to optochin i.e. growth inhibited by optochin)
35
Q

antibiotic resistance in penomocpcci Pneumococci :
can alter the structure of —— that are found on their surface
- —– as — cant bind to the penomococci and destroy their cell wall
- have different levels/degree of resistance which can be high/full level resistance or low/imtermediate level resistance
- its important to know if patient has been in area where there is — of resistance

A
  • penicillin-binding proteins (PBPs)
  • b lactam antibiotics
  • as penicillin
  • high resistance
36
Q

streptococci: antibiotic treatment :
most commonly use —– :
1- penicillin which is nearly all — susceptible
2- cephalosporin used for :
- —— penomococci
- used for treatment of:
- used if — with —
- don’t use for —-
3- vancomycin used for:
- if —-
- if —

A
  • cell wall active agents
  • b-hamelytic strepcocci
  • pencilin resistant
    -mengitis - ceftriaxone 3rd gen
  • rash w penicillin
  • don’t use for enterococci ( are intrinsically resistant )
  • if b- lactam analphylix
  • of resistant to b lactam suspected
37
Q

enterococci antibiotic treatment:
1-* First line treatment for enterococci is — and id resistant to this which many e.faecium are then —
2-However VRE (vancomycin resistant enterococci) are — so we cant use vancomycin so patient mat become —- and +/- develop significant — due to VRE
3- – treatment options with significant potential — and — : —

A
  • amoxilixllin
  • vancomycin
  • problematic
  • colonised
  • infection
  • limited
  • linezoilid
38
Q

prevention and control vaccination :

A
  • Pneumococcal vaccine
    available against some
    serotypes
  • 2 types of vaccine available
    – PPV 23 – only used if >2 yrs,
    recommended for >65 yrs of
    age
    – PCV 13 – Immunogenic from
    6/52 of age, part of childhood
    vaccination schedule, given at
    2, 6 and 13 months
  • At risk groups should also be
    offered vaccination
39
Q

principle of infection and prevention :
-group a step :
- notable diseases :

A
  • isolate in a single room if iGAS
    confirmed until 24 hours on appropriate antimicrobial
    therapy
  • public health

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