Staphylococci and Streptococci - Semmelweis Egyetem · 2015. 3. 12. · Staphylococci and...
Transcript of Staphylococci and Streptococci - Semmelweis Egyetem · 2015. 3. 12. · Staphylococci and...
Staphylococci and Streptococci
Dr. Béla Kocsis
2014.10.14
Semmelweis University Institute of Medical Microbiology
Gram-positiv cocci Staphylococci and Streptococci
Katalase-reaction
negative positive
Micrococcaceae Family
Nitrofurantoin Susceptibility
Positiv (susceptible)
Staphylococcus genus
Negativ (Resistant) Micrococcus genus
Streptococcus genus
Streptococcaceae Family
microscopic view
Gram-positiv cocci Staphylococci
Micrococcaceae Family
Micrococcus genus: apathogen Staphylococcus genus:
coagulase positiv: S. aureus
coagulase negativ: S. epidermidis, S. haemolyticus, S. saprophiticus, S. hominis
Coagulase test
Staphylococcus aureus
1) Microscopic morphology: Gram positive, 1 µm cocci arranged in grape-like clusters
Staphylococcus aureus
2) Cultivation • facultative anaerob • In bouillon: homogenous
turbidity • agar plate: 2-3 mm in
diameter, circular, golden yellow colonies
• pigment in non diffusable, fat soluble stains only the colonies
• S. aureus AU referes to gold • On blood agar: -haemolysis
• selective cultivation method:
7.5% NaCl
Staphylococcus aureus
3) Biochemical feature catalase + coagulase + Exocoagulase (free coagulase): • enzyme produced and released by the S. aureus, • binds to serum factor immunoglobulin, this complex can convert
fibrinogen to fibrin • detecting: coagulase tube test
Endocoagulase: „clumping factor” (bound coagulase): • on the bacterial surface, • direct convertion of fibrinogen to fibrin
• detecting: slide agglutination, latex-agglutination
latex-agglutination
Staphylococcus aureus
3) Biochemical feature
coagulase tube test
Staphylococcus aureus
4) Virulence factors
polysaccharide capsule slime layer (binds bacteria to catheters, grafts) teicholic acid, lipoteicholic acid (mediates the attachment of staphylococci to mucosal surfaces) adhesive proteins (collagene-, laminin-binding protein) clumping factor: endocoagulase mimikry by the fibrin layer macrophages can not reach them protein A (unique affinity for binding to the Fc fragment of immunoglobulin, prevents antibody-mediated immune clearance of S.aureus)
Staphylococcus aureus
4) Virulence factors on the bacterial cell surface
exocoagulase, fibrinolysin
DNase,
hyalurinidase,
phosphatase,
lipase
Staphylococcus aureus
4) Virulence factors: exoenzymes
Clot formation and lysis of fibrin
Invasivity in different tissues
Staphylococcus aureus
• Toxic Shock Syndrome Toxin (TSST-1)septic state , high fever, multi organ failer
• Staphylococcus enterotoxin (SE) leads to diarrhoeae and vomiting, toxico-infection
• exfoliative toxin split the intercellular bridges in the stratum granulosum epidermis
4) Virulence factors: exotoxins
Staphylococcus aureus
Superantigens bind to T helper on the T cell receptor V β site leads to
proliferation of T cells and overproduction of cytokins: TNF- β, IFN- γ, IL-2.
The patients get into septic state : hypotension, shock, mulit-organ-failer
4) Virulence factors: Superantigen exotoxin
Staphylococcus aureus
-haemolysin
- haemolysin
- haemolysin
-haemolysin
Leukocidin lysis of leukocytes
Pore forming on the cell surface
lysis of erythrocytes
4) Virulence factors: cytotoxins
Clinial pictures
Purulent infections on the site of infection of the skin
folliculitis, furunculus, carbunculus, woundinfections , otitis media, mastoiditis, mastitis
Invasive Infections
pneumonia, bakteraemia, sepsis, meningitis, ostitis, osteomyelitis, endocarditis
Toxin medaited infections
Gastroenteritis, TSS, Pemph. neonat, Scales Skin Syndrom
Source of infection : 5-10 % of population carry S. aures in the nose, nasopharynx Way of transmission by respitory droplets or direkt contact
Impetigo
Folliculitis
Furuncle Carbuncle
Local skin infections
• Osteomyelitis
• Mediastinitis
• Peritonitis
• Meningitis, Subduralempyema,
• Abscesse formation in all parenchymal organ
Deep purulent infections
Fig. 8.27 – Septic arthritis. Erythema and swelling of the left ankle joint
in a young girl with staphylococcal sepsis.
By courtesy of Mr. N.St.J.P. Dwyer
Septic arthritis
Arthrotomia, pus after Gram staining Gram positive cocci in clusters
Therapy of Staphylococcus aures infections
Antibiotic treatment
β-lactam antibiotics with β-lactamase Inhibitors
eg.: amoxicillin + clavulanic acid
Therapy of Staphylococcus aures infections
Penicillin group of antibiotics (as all β-laktams) Inhibit the peptidoglycan synthesis (cellwall synthesis) Target molecula PBP (Pencillin Binding Protein) a transpeptidase, responsible for the cellwall synthesis
β-lactam antibiotics
Peptidoglycan of Cell wall : NAM: N-acetyl-muramin acid : NAG: N-acetyl-glukosamin
NAM
NAG
NAM
NAG
NAM
PBP
Ala-Glu-Lys-D-Ala-D-Ala
Ala-Glu-Lys-D-Ala-D-Ala
Ala-Glu-Lys-D-Ala-D-Ala
beta-lactamase (penicillinase) production
Resistence to beta-lactams
Beta-lactamase production
(penicillinase production)
• Resistence only to Penicillin group
• Penicillin-binding Proteine (PBP) – Struktur modifing
• Resistance to all beta-lactame antibiotics:
– Penicillins
– Cephalosporins
– Karbapenems
– monobactams
– Beta-laktamase Inhibitors
MRSA: Methicillin Resistant S. aureus
Therefore the treatment: amoxicillin + clavulanic acid
Penicillinase inhibitor Penicillin derivative
Antibiotic with different target molecules :
Vancomycin Linezolid Mupirocin Clindamycin Daptomycin
Therefore the treatment is based on antibiogramm:
MRSA = methicillin resistent S. aureus
Methicillin belongs Penicillin group of antibiotics (β-laktam) Inhibtion of Peptidoglycan synthesis Target molecula PBP (Pencillin Binding Protein) Target molecule mutation PBP’2a modified target conferes resistance to all β-lactam antibiotics
Ala-Glu-Lys-D-Ala-D-Ala Ala-Glu-Lys-D-Ala-D-Ala Ala-Glu-Lys-D-Ala-D-Ala
Uneffective β-lactam Antibiotics
Peptidoglycan of Cell wall
NAM
NAG
NAM
NAG
NAM
PBP’2a
MRSA: methicillin resistent S. aureus in Europe 2012
Less than 1%
More than 25%
VRSA = vancomycin resistent S. aureus
Vancomycin effective agent against MRSA Inhibition of Cell wall synthesis Targetmolecule is D-Alanin in Murein Targer modification (D-Ala-lactate) leads to resistance VRSA
Ala-Glu-Lys-D-Ala-D-Ala Ala-Glu-Lys-D-Ala-D-Ala Ala-Glu-Lys-D-Ala-D-Ala
Vancomycin
Vancomycin
Vancomycin
Peptidoglycan of Cell wall
NAM
NAG
NAM
NAG
NAM
Coagulase-negativ Staphylococci
Coagulase-negativ Staphylococci
• Belong to the normalflora of the skin and mucosalayers
• Fakultative Pathogens
S. epidermidis
S. hominis
S. hemolyticus
S. saprophyticus
Staphylococcus epidermidis
• Morphology: Gram-positve cocci in grape-like clusters
• Cultivation: white pigment without hemolysis
• Biochemical features
– Katalase +
– Koagulase -
– Mannit -
Staphylococcus epidermidis
• Belongs to the normalflora of the skin
• On the intact skin causes no infection
• On plastic instruments biofilm formation
– exopolysaccharide
– Matrixproteins (Fibrin, Fibrinogen)
Attachment , colonisation
Bloodstream infection
Therapy: plastic devices should be removed Therapy based on antibiogram S. epidermidis resistance to beta-lactams: MRSE : methicillin resistant S. epidermidis Resistance to other group of antibiotics too: vancmomycin, linezolid
Staphylococcus epidermidis
Staphylococcus saprophyticus
1) Microscopic morphology: Gram-positive cocci grape-like clusters
2) Cultivation: no hemolysis on blood agar
3) Biochemical : coagulase negative, novobiocin resistent,
urease positive!
Clinical features: Belongs to the skin normalflora mainly on the genitals cystitist („honeymoon cystitis”) in young
sexualle active women
S. saprophyticus can bind to the uroepithel and by the urease activity NH3 will irritate the mucosalayer
Staphylococcus haemolyticus Staphylococcus hominis
1) Microscopic morfology: Gram-positiv cocci grape-like clusters
2) cultivation: white colonies weak or no hemolysis
3) Biochemical features : novobiocin susceptible
Belong to the normal flora of the skin :
Nosocomial pathogen biofilm production on catheter, canuls, plastic devices, tubes of intubation
Mucus layer damages help the invasion to the bloodstream
bacteraemia and sepsis
Streptococci
Gram positive cocci : Streptococcus genus
Morphology: Gram positive cocci 1m in diameter arranged in chains
Cultivation: demanding bacteria
blood agar media (-, -, - haemolysis)
1 mm in diameter roundish,
tiny needletip colonies
Biochemical feature: catalase negative
Classification of the Streptococcus genus
1. Haemolysis:
a) - haemolysis: Streptococcus pyogenes, S. agalactiae
b) -haemolysis: S. pneumoniae
c) non haemolytic: S. lactis, Enterococci
2.Lancefield grouping: according to the polysaccharide “C” in the cell
wall
serogroups: A, B, C, D, F, G human infections
“A” group: S. pyogenes
“B” group: S. agalactiae
“D” group: Enterococcus faecalis
Classification of the Streptococcus genus
3. “M” protein in the cell wall: serotypes
• S. pyogenes > 90 serotypes
• in certain diseases different serotypes are characteristic:
• e.g.: serotype 10 – scarlet fever;
• serotype 2, 4, 12, 49 – acut glomerulonephritis
• (nephritogen strains)
4. 16 S rRNA sequence coding DNA sequence:
• 6 clusters: anginosus, pyogen, mitis, salivarius, bovis, mutans
Streptococcus pyogenes
1) Microscopic morphology:
Gram positive cocci 1m in diameter arranged in long chains
• capsule is composed of hyaluronic acid
Streptococcus pyogenes
2) Cultivation: demanding bacteria (vitamin B)
blood agar media:
-haemolysis 1 mm, circular, tiny needletip colonies
S. pyogenes on blood agar
Streptococcus pyogenes
3) Biochemical features:
Antigen structure: Lancfield group “A”
according to M protein it is grouped in serotypes
Streptococcus pyogenes 4) Virulance factors
I. On the cell surface: lipoteicholic acid, F-protein, capsule II. Exotoxin: erythrogenic toxin – scarlet fever (capillar toxin) Spe A, B, C, F – streptococcal pyrogenic exotoxin
III. Streptolysin S and O (haemolysin): anti-streptolysin O titer – confirming rheumatic fever!
IV. Exoenzymes: hyaluronidase (,,spreading factor”) DNase streptokinase (cleaves plasminogen to plasmin promoting fibronolysis
5) Clinical pictures by S. pyogenes
I. Purulent infections: mediated by S. pyogenes bacterium
II. Toxin mediated infections: Scarlate fever, TSST
III. Complications: Post-streptococcal diseases: typ2 and typ 3 hypersensitive reactions
5) Clinical pictures
I. Pyogenic infections (mediated by the bacterium)
• pharyngitis,
• tonsillitis follicularis,
• otitis media, sinusitis
• meningitis,
• pneumonia, endocarditis
• puerperal fever (Semmelweis)
• Impetigo,
• erysipel
• myositis
• necrotising fasciitis (“fleish-eating bacterium”)
Streptococcus pyogenes 5) Clinical pictures
Tonsillitis follicularis Impetigo contagiosa
Ignaz Semmelweis
Ignaz Semmelweis demonstrated that
childbed fever (puerperal fever),
caused by streptococcal infections,
was transmitted to patients by doctor’s
hands
Pioneer of antisepsis in
obstetrics
Women giving birth in hospitals
by medical students and
physicians were 4x more likely
to contract puerperal fever
compared to those by midwives
Handwashing with chlorin water
(leach powder)
Childbed fever (puerperal fever) by S. pyogenes
Streptococcus pyogenes 5) Clinical pictures
Nekrotising fasciitis
Erysipel
Streptococcus pyogenes 5) Clinical pictures
II. Toxin mediated diseses
• Scarlet fever: mediated by erythrogen toxin, which can destroy the endothel cell of capillaries – red rash
• Can not be formed into toxoid! NO vaccination
• 2 days after the infection exanthems on the skin and throat
Scarlet fever Strawberry tongue: papilla hyperthrophy on the tounge
Exanthems on the skin
III. Poststreptococcal diseases
(complications of a S. pyogenes infection)
1.Rheumatic fever:
Typ 2 hypersensitive reaction: surface anigen of the heart muscle is similar to the Str. pyogenes antigen(M-protein) antibodies bound to the heart muscle
• inflammatory changes in the heart (pancarditis)
• endocarditis: damage of heart valves
2. Acute glomerulonephritis (GN): immuncomplex mediated
Immunkomplexes in joints: polyarthritis
Immunkomplexes in the glomerulus : nephritis
• Typ 3 hypersensitive reaction: immuncomplexes bind to the glomerulus basalmembrane glomerulonephritis
• Hypertonia and oedema
3. Erythema nodosum:
• subcutan nodles, immuncomplex mediated
III. Poststreptococcal diseases (complications)
Immunity: Antibacterial: you can have tonsillitis follicularis more than once (several serotypes) Antitoxical: you acquire scarlet fever only once (erythrogenic toxin has the same structure in all the strains)
Treatment: penicillin (natural susceptible to penicillin), • macrolid (if the patient has penicillin allergy) • complications should be prevented.
1) Microscopic morphology: Gram positive cocci 1m in diameter arranged in chains
2) Cultivation: blood agar media: -haemolysis (narrow)
1 mm in diameter circular, tiny needletip colonies
diagnostic antibiotic: bacitracin (R)
CAMP +
3) Antigen structure: Lancfield group “B”
4) Pathogenicy: colonisation in the vagina
5) Clinical pictures: during pregnancy: abortion
during delivery the neonates can be infected: newborn pneumonia, ARDS, meningitis, sepsis
(Screening of pregnant women after the 35th week of gestation!)
• Treatment and prevention: ampicillin
Streptococcus agalactiae
Enterococcus genus
1) Microscopic morphology: Gram
postive cocci (elongated) 1m in diameter arranged in short chains
Antigen structure: Group D Lancfield type
Enterococcus faecalis, Enterococcus faecium
2) Cultivation: on blood agar greyish colonies
• (sometimes green court under the colony)
• selective culture media – black colonies
(E67 culture media)
3) Biochemical feature: esculin (polysaccharid) hydrolysis
Enterococcus faecalis, Enterococcus faecium
Clinical pictures:
enteric cocci : present in the intestine (normal flora)
facultative pathogen
inflammation of bile tract and urinary tract
nosocomial infection after surgery
Intestinal trauma /perforation sepsis, peritonitis
Treatment: natural resistance cephalosporin and sulfonamid!
Th.: synergistic combination: ampicillin + gentamycin
Th: vancomycin increased level of resistance to glycopeptid :
VRE: vancomycin resistant Enterococci
Streptococcus viridans group (S. mutans, S. mitis, S. sanguis,
S. salivarius, S. milleri)
heterogenous collection of - haemolytic Streptococci
,,viridae” – Latin term for green
Member of the normal flora of the oral cavity.
• Cultivation on blood and chocolate agar: - haemolysis
• Separate from S. pneumoniae S: normal flora optochin R
• clinical picture: In oral cavity: colonisation on the teeth dental plaque formation dental caries
• If Streptococcus viridans enter the circulation cause subacute endocarditis
Peptostreptococci
Anaerobic Streptococci!
• Normal flora of the oral cavity, gastrointestinal tract.
• Polymicrobic, pyogenic infections, abscess formation in the abdominal cavity, lung and brain or in the oral cavity
• Treatment: metronidazol, clindamycin
Abscess
Streptococcus pneumoniae
1) Microscopic morphology:
Gram positive diplococci,
,,flame-shaped” or
,,lancet-shaped”
Fig. 2.21 Pneumococcal pneumonia. Preparation of sputum showing
predominance of pneumococci mostly as lanceolate diplococci. Gram
stain. By courtesy of Dr. J.R. Cantey
Streptococcus pneumoniae
Streptococcus pneumoniae
2) Cultivation:
• blood and chocolate agar -haemolysis
• autolysis: ageing colonies are umbilicated
3) Biochemical features optochin sensitivity (S) separate from the viridans group
4) Virulenc factor Polysaccharide capsule
Streptococcus pneumoniae
• Can not be grouped with the Lancefield technique!
• based on capsule – 91 serotypes
• ,,quellung”-reaction (German ,,swelling”): anticapsular antibody plus pneumococci
greater refractiveness around the bacteria by microscope
Quellung reaction of
S. pneumoniae
Streptococcus pneumoniae
Clinical picture:
lobar pneumonia
sinusitis, otitis media bacteriaemia, meningitis
ulcus serpens corneae (eye infection)
Source of infection: 5-10% of population carry S. pneumoniae in nose, throat
Streptococcus pneumoniae
Treatment: high penicillin resistance decreased affinity of the antibiotic to PBP
Therapy: macrolid, fluoroquinolones
Prevention: 13-valent polysaccharide vaccine (conjugated)
obligatory vaccine for new borns ( in Hungary since 2014 July)
recommended: 1. children (born before 2014 July)
2. adults above 65 years of age
3. adults with chronic disease
(COPD, heart failure)
4. patient after splenectomy
Vaccinations against bacterial infections
1) BCG = against Mycobacterium tuberculosis (living attenuated bacterium)
2) aP = against Bordetella pertussis (acellulare Pertusis vaccination)
3) Diphtheria = against Corynebacterium diphtheriae (toxoid)
4) Tetanus = against Clostridium tetani (toxoid)
5) Hib = against Haemophilus influenzae b capsule antigen
6) Neisseria meningitidis capsule antigen
7) Streptococcus pneumoniae capsule anigen
8) Salmonella typhi killed bacteria (polysaccharide derivative)
9) Vibrio cholerae killed bacteria