Download pyogenic cocci

Cocci
Cocci
5 pathogenic cocci/ pyogenic cocci
- G+: staphylococcus
S. aureus
streptococcus
S. pyogenes, S. pneumoniae
- G-: Neisseria
N. meningitidis, N. gonorrhea
(I) Staphylococcus
Staphylococcus
Primary reservoir
-Human carriers
-Nasopharynx, throat, skin
>30 species
- main bacteria in the nosocomial infection
- S. aureus: the most virulent species
- S. epidermidis: opportunistic pathogen
- S. saprophyticus: rarely cause human diseases
Comparison
Properties
S. Aureus
S. Epidermidis
S. saprophyticus
Pigment
Golden yellow
white
citrine
Coagulase
+
+
+
-
-
SPA
+
+
-
-
pathogenicity
strong
weak
-
Mannitol
Thermostable
nuclease
Hemolysin
Biological characteristics
•
•
•
•
•
Grape like-clusters, no capsule
Facultative anaerobes
Liposoluble pigments
Hemolysis
Resistance
Pathogenicity (S. aureus)
• Virulence factors
 invasiveness
- surface structure
SPA
- invasive enzymes
coagulase
 Toxin---exotoxins
- hemolysins/ Staphylolysin
- leukocidin
- Staphylococcal enterotoxin
- toxic shock syndrome toxin-1, TSST-1
- exfoliative toxin/
epidemolytic toxin
SPA inhibits phagocytosis
PHAGOCYTE
Fc receptor
SPA
IgG
Fab
Fc
BACTERIUM
Free protein A binds to Fc of IgG, blocking Fc
receptors and is thus anti-phagocytic.
Pathogenicity (S. aureus)
• Disease
Invasive infection/ pyogenic infection
- local infection: lesion is limited in local area
- organ infection: pneumonia, meningitis
- systemic infection: septicemia, pyemia
Bactermia (from abscess, wound, burn) , Osteomyelitis (tibia)
,Pneumonia
folliculitis
Boil/ furuncle
carbuncle
Impetigo--staph skin infection,
multiple pustules (small
skin abscesses)
Pseudomembranous Enteritis, PME
Pseudomembranous Colitis
Pathogenicity (S. aureus)
• Disease
 Toxin-associated diseases
- food poisoning (enterotoxin)
- TSS (TSST-1)
sudden high fever, shock, kidney failure, red skin rash
- SSSS (exfoliative toxin)
staphylococcal scalded skin syndrome
- staphylococcal enterocolitis- dysbacteriosis
Staphylococcal scalded skin syndrome (SSSS)
-- most often occurs in infants
and young children
Low mortality rate
Skin blister--denudation (like scald)
Laboratory diagnosis
•
•
•
•
Direct examination: Gram Stain
Primary media: BAP
Differential Tests.
Mannitol Salts
Coagulase
DNase
Enterotoxin
Antibiotic Sensitivity (plasmid, B
lactamase) : penicillin
/methicillin/vancomycin
Lysostaphin test
Staphylococcus
Micrococcus
API STAPH Kit
coagulase negative staphylococci
Staphylococcus epidermidis
• Major component skin flora
• Opportunistic infections (less common than S.aureus)
– urinary tract infection (UTl)
– septicemia
• Identification
– wound infection
– Non-hemolytic (sheep blood agar)
• Nosocomial infections
– Does not ferment mannitol
– bacterial endocarditis
– Coagulase-negative
Staphylococcus saprophyticus
• urinary tract infections
(II) Streptococcus
•Widely exist:
-water, air, feces, human nasopharynx
•Diseases:
-pyogenic infection
- scarlet fever
-streptococcal hypersensitive disease
- rheumativ fever
(II) Streptococcus
- G+, arranged in chains
- Nutrient requirement: high
*fastidious (flesh-eating bacteria)
- Facultative/ obligate anaerobe
- On blood agar:
*different hemolysis
- Catalase negative (staphylococci +)
Classificaton
• based on hemolytic activity
- α-hemolytic strep
incomplete hemolysis
opportunistic pathogens
- β-hemolytic strep
complete hemolysis
main human pathogens
-γ-hemolytic strep
no hemolysis
no pathogenicity
Hemolysis
alpha
beta
gamma
Classificaton
• Antigenic structure
- polysaccharide antigens (C Ag)
* group-specific antigen
* 20 groups (A-H, K-V)
* group A main human pathogens
- surface protein antigens (M Ag)
* type-specific antigen
* group A>80 serotypes
Pathogenicity (Step. Group A)
• Virulence factors
Surface structure
- LTA: adhere to host cells
- M- protein
- Peptidoglycan
Lipoteichoic Acid and F-protein
lipoteichoic acid
F-protein
fibronectin
epithelial cells
M protein
IMMUNE
Complement
IgG
r
r
r
M protein
NON-IMMUNE
peptidoglycan
fibrinogen
r
r
r
Pathogenicity (Step. Group A)
• Virulence factors
 Invasive enzymes
- hyaluronidase (spreading factor)
- streptokinase (SK)
- streptodornase (SD)


Erythrogenic toxins
---pyrogenic exotoxin
Toxins---exotoxins
scarlet fever toxin
- streptolysin (hemolysin)
- protein
- erythrogenic toxin
- serotype A, B, C
- scarlet fever
streptolysins
Properties
Streptolysin O
(SLO)
Streptolysin S
(SLS)
O2
Oxygen-labile
Oxygen-stable
Antigenicity
Strong (ASO test)
weak
Biological
Destroy WBC, platelet
virulence of Mφ, NC
Destroy WBC
virulence of many
tissues
Chemical
Protein (MW 60 000)
Polypeptide (28 aa)
Anti-SLO test (ASO test)
• A neutralization test between the toxin (SLO)
and its specific anti-toxin (ASO) which is used
to diagnose or monitor rheumatic fever caused
by group A strep.
Pathogenicity (Strep. Group A)
• Disease

3 types of infections
- pyogenic infection:
skin & subcutaneous infection, impetigo,
lymphangitis, septicemia
- toxin-associated diseases
pharyngitis--scarlet fever
- hypersensitive disease
acute glomerulonephritis, rheumatic fever
pyogenic infection
Erysipelas
Abscess with surrounding cellulitis
Acute tonsillitis--There is a risk of developing
rheumatic fever
Erysipelas on the cheek
toxin-associated diseases
Strawberry tongue
Red rash
Paly around mouth
Diseases caused by other streptococci
Group B strep.
- neonatal infection
- adult infections: endometritis, pneumonia, meningitis,
endocarditis
Group C strep.
- epidemic sore throat, acute glomerulonephritis
Group G strep.
- sore throat, cellulitis, erysipelas
Group D strep.
- nosocomial infection, urinary infection, biliary tract
infection, peritonitis
Laboratory diagnosis
• Direct examination: Gram Stain
• Primary culture
• ASO Tests.
Prevention and treatment
Treat the pharyngitis and tonsillitis in
time
Antibiotics: penicillin for the first choice
(III) Pneumococcus
Characteristics
• Morphology & cultivation properties
- G+, arranged in pairs, bullet shape
- capsule: polysaccharide
- blood agar or chocolate blood agar, festidious
- α-hemolysis
- autolysis
- bile solubility test: +
*distinguish from other α-hemolytic strep.
- ferment inulin
Pathogenicity
• Virulence factors
- capsule
- pneumolysin & neuraminidase
- Surface protein adhesin and secretory IgA protease.
- Teichoic acid and the Peptidoglycan fragment,
phosphorylchorine .
Pathogenicity
• Main disease
- pneumonia
*particularly young and old
*after damage to upper respiratory tract
e.g. following viral infection
- bacteremia
- meningitis
- middle ear infections (otitis media)
Laboratory diagnosis
• Differentiate S. pneumoniae from other αhemolytic strep.
+
- bile solubility test
- optochin sensitivity test
-capsule swollen reaction
- animal test
-
Treatment & prevention
(S. pneumoniae)
• Sensitive to a wide range of antimicrobial
agents, but resistance is common:
penicllin, erythromycin, chloramphenicol, sulphonamides,
clindamycin, vancmycin
• Prevention
polysaccharide vaccine
14 capsule types mixed vaccine
Summary Figure (Identification Scheme)
Note: Strep. viridans
are alpha hemolytic and
negative for all the tests
below
GRAM POSITIVE COCCI
Catalase
Streptococcus (pairs & chains)
+
Staphylococcus (Clusters)
Coagulase
+
S. aureus
&hemolytic
mannitol
yellow
-
Hemolysis
•
S. epidermidis
nonhem olytic (usua lly)
mannitol
(2)
white
•
BETA: Bacitracin
S .pyogenes (group A)
+
CAMP/Hippurate
+
S. agalactiae (group B)
ALPHA: Optochin/Bile Solubility
GAMMA: Bile Es culin
+
S. pneumoniae
+ 6.5% NaCl +
Group D*
Enterococcus
Bile Esc ulin
NaCl
Group D*
+ 6.5%
Non-Enterococcus
(*can also be beta or alpha hemolytic)
Bile solubility test
Streptex antiserum
optochin sensitive
Not optochin sensitive
Quellung reaction
•
•
•
using antisera
capsule "fixed"
visible microscopically
Latex agglutination - streptococci
(IV) Neisseria
Genus Neisseria > 10 species
•N. Meningitidis
- meningitis
- low prevalence but high mortality
•N. Gonorrhoeae
- human gonorrhea
- high prevalence but low mortality
Biological characteristics
• G-, coffee bean-shaped or kidney-shaped,
in pairs
• Capsules and pili
• Fastidious
• Resistance: very low
Polymorphonuclear cells
Biological characteristics
• Oxidase positive
• Culture: 5-10% CO2
• Thayer Martin.
selective
chocolate agar
heated blood
Pathogenesis--meningococcus

Virulence factors
-pili: attach to nasopharyngeal mucosa
-capsule
-endotoxin: damage capillary blood vessel

Transmission
-respiratory droplets

Disease
- epidemic cerebrospinal meningitis
Pathogenesis--gonococcus

Virulence factors
-pili
-IgA, protease
-outer membrane protein (OMP)
-LPS

Transmission
-sexual contact
-indirect contact (basin, towel, etc)

Disease
- gonorrhea
N. meningitidis
N. gonorrhoeae
Virulence Factors
Similar, but –
Differences
in utilization
LPS
LPS
Capsule
IgA protease
Hemolysin
IgA protease
PILI
Opacity (OPA) proteins
Outer Membrane Proteins
PILI
Opacity (OPA) proteins
Outer Membrane Proteins
X
NO capsule
NO hemolysin
Neisseria gonorrhoeae
• After 2-14 days
• Found only in man
• Gonorrhea: second most common venereal disease
Gram stain of pure culture
Urethral exudate
Using the Gram stain in patient specimens, the organisms are most often
observed in polymorphonuclear leukocytes
Neisseria gonorrhoeae

adults
-transmission: STD (sexually tranmitted disease)
-clinical dsease: genitourinary tranct infection
urethritis, prostatitis, epididymitis (male)
cervix inflammatin (female)
infertility

newborns
-ophthalmia neonatorum
Neisseria gonorrhoeae
Pili = key in anchorage of
organisms
to mucosal epithelium.
Nonpiliated gonococci are avirulent
OUTER MEMBRANE PROTEINS
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]
Urethritis
Bartholin’s Duct
Purulent conjunctivitis/Ophthalmia neonatorum
Infection in newborns during vaginal delivery
Disseminated gonococcal infection (DGI).
Fever, polyarthritis
(or monoarticular septic arthritis),
and/or dermatitis
(pustules on a hemorrhagic base).
Smear
• polymorphonuclear cell
• G- cocci, many in cells
• Culture
Antibiotic therapy
• lactamase-resistant cephalosporin
– e.g. ceftriaxone
• resistant strains
– common
– produce lactamases
– destroy penicillin
Prevention and treatment
penicillin
1% silver nitrate--- ophthalmia neonatorum
Meningococcal
meninigitis
Neisseria meningitidis
• resides in man only
• usually sporadic cases
– mostly young children
• outbreaks
– adults
– crowded conditions
* e.g. army
barracks
Upper respiratory
tract infection
– adhesion pili
• 1-4 days
• Second most common
meningitis
– pneumococcus, most common
• Fatal if untreated
• Responds well to antibiotic
therapy
– penicillin
Bloodstream
Brain
Diagnosis
• spinal fluid
– Gram negative diplococci
within polymorphonuclear cells
– meningococcal antigens
•
Culture
– Thayer Martin agar
Prevention
• capsule
– inhibit phagocytosis
•
anti-capsular antibodies
– stop infection
• antigenic variation
– serogroups
•
vaccine
– multiple serogroups
Pseudomonas aeruginosa
Pseudomonas aeruginosa
• Widely distributed in nature
• Frequently present in small numbers in the normal
intestinal flora and on the skin
• Commonly present in moist environments in hospitals
• It is primarily a nosocomial pathogen
Typical Organisms
• Gram- rod
• Unipolar flagellum (1~3) ---actively mobile
• Occurs as single bacteria, in pairs,
and occasionally in short chain
• Capsule
• Pili in strains obtained from clinical
specimens
Culture
• Grow readily on many
types of culture media
• Smooth and round colonies
• Multiple colony types in one culture
• Fluorescent greenish color
• Sometimes produce a sweet or grape-like or corn
taco-like odor
Culture
• Obligate aerobic
• Grow well at 37~42℃and no growth at 4℃
• Produce water-soluble pigments
Pyocyanin; Pyoverdin; Pyorubin; Pyomelanin
• Produce hemolysin
• Oxidase-positive
• Ferment glucose but not other carbohydrates
Diverse sites of infection by
P aeruginosa
Who are at risk?
• People with cystic fibrosis
• Burn victims
• Individuals with cancer
• Patients requiring extensive stays in
intensive care units
Control and Treatment
•
The spread of Pseudomonas is best controlled by cleaning
and disinfecting medical equipment.
•
In burn patients, topical therapy of the burn with
antimicrobial agents such as silver sulfadiazine, coupled with
surgical debridement, has markedly reduced sepsis.
•
Susceptibility testing is essential.
•
The combination of gentamicin and carbenicillin can be very
effective in patients with acute P aeruginosa infections.
Summary
• Concepts
-Pathogenic/ pyogenic cocci
-SPA
-ASO test
• Pathogenicity of 5 pathogenic cocci