The Staphylococci
Morphology & Identification
?Gram positive
?Facultative anaerobes
?Grape like-clusters
?Catalase positive
?Major components of
normal flora
?skin
?nose
Catalase test（ 过氧化氢
酶）
(-) (+)
Staphylococcus aureus
Antigenic Structure
Pathogenesis
? Catalase
? Coagulase
? Hyaluronidase and Lipase
? Hemolysin or sphingomyelinase C
? Leukocidin
? Exfoliative Toxin
? Toxic Shock Syndrome Toxin
(superantigen)
? Enterotoxins
Protein A immunoglobulin
Fc receptor
BACTERIUM
PHAGOCYTE
Pathogenesis of staphylococcal infections
Stye:麦粒肿
Carbuncle:痈
Impetigo,脓疱疮
Suppurative
? Skin
? Furuncle; Protein A,Leukocidin,Hemolysin
? Stye; lipase
? Impetigo; contagious
? Epidermal necrolysis
? Exfoliative Dermatitis (6,7,8); Exfoliative toxin
? Mastitis
? Abscess (deep tissue); granulation; coagulase,hyaluronidase (burn,wound)
? Systemic
Bactermia (from abscess,wound,burn),Osteomyelitis (tibia),Pneumonia
? Food poisoning
? Toxic shock syndrome
? babies
– scalded skin syndrome
* Exfoliatin
? fever
? scarlatiniform rash
? desquamation
? vomiting
? diarrhea
? myalgias
? not a human infection
? food contaminated from humans
– growth
– enterotoxin
? onset and recovery both occur within few hours
? Vomiting/ nausea/ diarrhea/ abdominal /pain
Infections associated with indwelling devices
Laboratory
? A,Direct examination; Gram Stain
? B,Primary media; BAP
? C,Differential Tests,
1,Mannitol Salts
2,Coagulase
3,DNase
? D,Phage typing
? E,Antibiotic Sensitivity (plasmid,
B lactamase), penicillin
/methicillin/vancomycin
Lysos ta ph in te s t
Staphylococc us Mic rococc us
API STAPH Kit
G R A M P O S I T I V E C O C C I
S,au r eu s
& h em o l yt i c
m an n i to l
ye l l o w
+ -
Sta p h y l o c o c c u s (C l u s te r s ) Str e p to c o c c u s ( p a i r s & c h a i n s )
C a ta l a s e
? B ET A, B ac i tr ac i n S,p yo g en es (g r o u p A )
C A M P/ H i p p u r at e S,ag al ac ti ae (g r o u p B )
H e m o l y s i sC o a g u l a s e
S,ep i d er m i d i s
n o n h em o l yt i c (u su a l l y)
m an n i to l
w h i te
(2 ) A L PH A, O p to ch i n / B i l e So l u b i l i ty S,p n eu m o n i ae
? G A M M A, B i l e Es cu l i n 6,5% N aC l G r o u p D *
En te r o co cc u s
B i l e Es c u l i n 6,5% N aC l G r o u p D *
N o n - En te r o co cc u s
(* c an al s o be be t a or al ph a he m ol y t ic )
N o t e, S t r e p, v i r i d a n s
a r e a l p h a h e m o lyt i c a n d
n e g a t ive f o r a ll t h e t e st s
b e lo w
+
+
+
++
+
+
-
-
S um m a r y Fi gu r e ( I de nt i f i c a t i on S c he m e )
Staphylococcus epidermidis
? major component skin flora
? opportunistic infections
– less common than S.aureus
? nosocomial infections
– heart valves
? Identification
– Non-hemolytic (sheep blood agar)
– Does not ferment mannitol
– Non-pigmented
– Coagulase-negative
Staphylococcus saprophyticus
? urinary tract infections
? coagulase-negative
– not differentiated from S,epidermidis
The Streptococcus
Streptococcus
Morphology & Identification
? facultative anaerobe
? Gram-positive
? Chains or pairs
? Catalase negative
(staphylococci are catalase positive)
Cell surface structure of S pyogenes
and extracellular substances
?Lancefield groups
*one or more species per group
*surface antigens,M,T,R
groupable streptococci
?A,B and D
–most important
?C,G,F
–Rare
Non-groupable
?S,pneumoniae
–pneumonia
?viridans streptococci
–e.g,S,mutans
*dental
caries
Lipoteichoic Acid and F-protein
fibronectin
lipoteichoic acid
F-protein
epithelial cells
M protein
? major target
– natural immunity
? strain variation
– antigenicity
? re-infection
– occurs with different strain
M protein
M protein
fibrinogen
r r r
peptidoglycan
r r r
IgG
Complement IMMUNE
NON-IMMUNE
Toxins & Enzymes
Hemolysis
alpha
beta
gamma
Classofication of Streptococci of Particular Medical Interest
Pathogenesis of S pyogenes infections,
S,pyogenes (Group A) -suppurative
? affect all ages peak incidence at
5-15 years of age
? non-invasive
– pharyngitis
– skin infection,impetigo
? invasive bacteremia
– toxic shock-like syndrome
– "flesh eating" bacteria
– pyrogenic toxin
? Scarlet fever
? rash
? erythrogenic toxin
? rheumatic fever
? inflammatory disease
? life threatening
? chronic sequalae
? fever
? Heart
? Joints
? rheumatic NOT rheumatoid arthritis
? Acute glomerulonephritis
immune complex disease of kidney
Rheumatic fever -etiology
? M protein
– cross-reacts heart myosin
– autoimmunity
? cell wall antigens
– poorly digested in vivo
– persist indefinitely
Post-infectious diagnosis (serology)
? antibodies to streptolysin O
? important if delayed clinical sequelae
occur
? superantigen
? T cell mitogen
? activates immune
system
Group B streptococcus -
identification
? neonatal meningitis
? septicemia
? transmission
– vaginal flora
? ? hemolysis
? hippurate hydrolysis
? CAMP reaction
– increases ? hemolysis of S,aureus
Group D streptococcus
? Growth on bile esculin agar
– black precipitate
? 6.5% saline
? grow
– enterococci
? no growth
– non-enterococci
Enterococci
? distantly related to other streptococci
? genus Enterococcus
? gut flora
– urinary tract infection
? fecal contamination
– opportunistic infections
? particularly endocarditis
? most common E,(S.) faecalis
? resistant to many antibiotics
– including vancomycin
? terminal D-ala replaced by D-lactate
Viridans streptococci
? diverse species
? oral
? dental caries
? ? hemolytic and negative for other tests
? non-groupable,
? includes S,mutans
– endocarditis
– tooth extraction
Streptococcus pneumoniae
S,pneumoniae - diplococci
? capsule,
? pneumolysin,
? Surface protein
adhesinand secretory IgA
protease,
? Teichoic acid and the
Peptidoglycan fragment,
phosphorylchorine,
? leading cause pneumonia
– particularly young and old
– after damage to upper
respiratory tract
*e.g,following viral infection
? bacteremia
? meningitis
? middle ear infections (otitis media)
G R A M P O S I T I V E C O C C I
S,au r eu s
& h em o l yt i c
m an n i to l
ye l l o w
+ -
Sta p h y l o c o c c u s (C l u s te r s ) Str e p to c o c c u s ( p a i r s & c h a i n s )
C a ta l a s e
? B ET A, B ac i tr ac i n S,p yo g en es (g r o u p A )
C A M P/ H i p p u r at e S,ag al ac ti ae (g r o u p B )
H e m o l y s i sC o a g u l a s e
S,ep i d er m i d i s
n o n h em o l yt i c (u su a l l y)
m an n i to l
w h i te
(2 ) A L PH A, O p to ch i n / B i l e So l u b i l i ty S,p n eu m o n i ae
? G A M M A, B i l e Es cu l i n 6,5% N aC l G r o u p D *
En te r o co cc u s
B i l e Es c u l i n 6,5% N aC l G r o u p D *
N o n - En te r o co cc u s
(* c an al s o be be t a or al ph a he m ol y t ic )
N o t e, S t r e p, v i r i d a n s
a r e a l p h a h e m o lyt i c a n d
n e g a t ive f o r a ll t h e t e st s
b e lo w
+
+
+
++
+
+
-
-
S um m a r y Fi gu r e ( I de nt i f i c a t i on S c he m e )
Streptex antiserum
Latex agglutination - streptococci
Quellung reaction
? using antisera
? capsule "fixed"
? visible microscopically
Not optochin sensitive optochin sensitive
Bile solubility test
Prevention and Treatment
? Immunity ; 14 capsule types mixed
vaccine
? Most strains susceptible to
penicillin,but resistance is
common
? Gram negative
? diplococci (pairs of
cocci)
? oxidase positive
? Culture,5-10% CO2
? Thayer Martin,
– selective
– chocolate agar
* heated blood
Neisseria
Capsule
LPS
N,meningitidis
Virulence Factors
Similar,but –
Differences
in utilization
Hemolysin
IgA protease
PILI
Opacity (OPA) proteins
Outer Membrane Proteins
N,gonorrhoeae
LPS
PILI
Opacity (OPA) proteins
Outer Membrane Proteins
IgA protease
NO capsule
NO hemolysin X
Neisseria gonorrhoeae
Using the Gram stain in patient specimens,the organisms are most often
observed in polymorphonuclear leukocytes
Gram stain of pure culture Urethral exudate
? After 2-14 days
?Found only in man
? Gonorrhea,second most common venereal
disease
Pili = key in anchorage of
organisms
to mucosal epithelium,
Nonpiliated gonococci are avirulent
Porin proteins (Por) = prevent phagolysosome fusion & allow
intracellular survival [ also called protein I]
Opacity proteins (Opa) = binding of organisms to epithelium
[also called protein II]
Reduction-modifiable proteins (Rmp) = protection against
bactericidal antibodies [ also called protein III]
Neisseria gonorrhoeae
OUTER MEMBRANE PROTEINS
Bartholin’s Duct Urethritis
Disseminated gonococcal infection
(DGI),
Fever,polyarthritis
(or monoarticular septic arthritis),
and/or dermatitis
(pustules on a hemorrhagic base),
Purulent conjunctivitis/Ophthalmia neonatorum Infection in
newborns during vaginal delivery
Smear
? polymorphonuclear cell
? Gram negative cocci
many in cells
? Culture
? ? lactamase-resistant cephalosporin
– e.g,ceftriaxone
? resistant strains
– common
– produce ? lactamases
– destroy penicillin
Antibiotic therapy
N,meningitidis
(the "meningococcus")
Neisseria
meningitidis
? resides in man only
? usually sporadic cases
– mostly young
children
? outbreaks
– adults
– crowded conditions
* e.g,army
barracks
? 1-4 days
? Second most common
meningitis
– pneumococcus,
most common
? Fatal if untreated
? Responds well to
antibiotic therapy
– penicillin
Upper respiratory
tract infection
– adhesion pili
Bloodstream
Brain
Meningococcal
meninigitis
Diagnosis
? spinal fluid
– Gram negative
diplococci
within
polymorphonuclear cells
– meningococcal
antigens
? Culture
– Thayer Martin agar
? capsule
– inhibit phagocytosis
? anti-capsular antibodies
– stop infection
? antigenic variation
– serogroups
? vaccine
– multiple serogroups
Prevention