pyogenic cocci - semmelweis egyetemsemmelweis.hu/mikrobiologia/files/2014/10/fod_04b.pdf ·...
Post on 26-Mar-2020
4 Views
Preview:
TRANSCRIPT
PYOGENIC COCCI
Gram + Gram –
Micrococcaceae family Streptococcaceae family Neisseriaceae family
Micrococcus Streptococcus Neisseria
Moraxella
S. pyogenes (A) Kingella
Staphylococcus S. agalactiae (B)
S. pneumoniae N. meningitidis
Enterococcus (D) N. gonorrhoeae
viridant group
S. aureus coagulase negative
staphylococci
(CNS)
Neisseria
Gram negative diplococci;
bean-shaped
N. gonorrhoeae on
chocolate agar
Very fastidious bacteria:
chocolate agar and
increased CO2
N. gonorrhoeae, N. meningitidis: obligate human pathogens!
Cell wall: LOS instead of LPS (lipo-oligosaccharide).
Oxidase test
• performance:
– filter paper on microscope slide
– add oxidase reagent
(= parephenylene-diamine derivative)
– add bacteria
– positivity: pink / purple colour
Oxidase +: Pseudomonas, Neisseria, Vibrio, Campylobacter
• purpose: detection of cytochrome-oxidase enzyme
• diagnostic use: differentiation of obligate aerobes
+ -
Neisseria gonorrhoeae
(Gonococcus)
• Virulence factors
– No capsule!
– surface fimbriae, surface proteins (Opa) →
adhesion
– LOS → inflammation
– survives inside neutrophil granulocytes → IC.!
– IgA protease
– complement deficiency → invasive infections
Neisseria gonorrhoeae
• Transmission
– sexual (STI/STD)
– perinatal (birth canal) → conjunctiva of newborn
• Clinical picture
– Acute urethritis (men): dysuria, burning pain, purulent exudate („Bonjour-drop”)
– cervicitis, urethritis (women): often asymptomatic!
– vaginitis in teenagers
– blenorrhoea (ophtalmia) neonatorum → blindness!
Neisseria gonorrhoeae
Purulent urethra exudate
„Bon jour” droplet
N. gonorrhoeae in pus,
methylene blue staining
Diagnostics
– specimen from purulent exudate → direct
Gram or methylene blue staining
– special transport medium (NO cooling)
– immediate inoculation on chocolate agar,
incubation in increased (5%) CO2
– in cervical, rectal specimen: selective media
Treatment
– earlier: penicillin, today rather 3. gen.
cephalosporin (ceftriaxon)
– If suspicion also for chlamydia: additional
macrolide (azythromycin)
– For newborns: Credé eye drops (silver
acetate); today rather tetracycline or
macrolide eye drops
Neisseria meningitidis
(Meningococcus)• Virulence factors
– CAPSULE → 13 serotypes (A, B, C, D, H, I, K, L,
W-135, X, Y, Z, 29E)
– similar to N. gonorrhoeae (fimbriae, proteins,
LOS)
• Transmission
– air droplets
– nasopharyngeal colonisation precedes disease!
– carriage!
Neisseria meningitidis
• Clinical picture
– always bacteremia (meningococcaemia)
first, and not direct spread from
nasopharynx to CNS → purulent meningitis
(meningitis epidemica)
– petechiae, necrotic haemorrhagic rush
– fulminant sepsis
– Waterhouse-Friderichsen sy.: necrosis of
adrenalin glands (both sides)
– rarely: endocarditis, pneumonia, arthritis
Neisseria meningitidis• Diagnostics
– liquor sediment Gram st. → IC or EC
– liquor latex agglutination
– hemoculture obligatory!
– blood agar, cholcolate agar, increased CO2
– cooling of specimen is forbidden!
• Therapy
– empiric: cefotaxim, ceftriaxon
– targeted: penicillin, ceftriaxon
• Chemoprofilaxis
– rifampin, ciprofloxacin for contacts
Neisseria meningitidisEpidemiology
• more frequent in wintertime
• newborns are most sensitive (after finishing
breast feeding)
• in overcrowded places (e.g. military service,
summer festivals)
• „B” capsular antigen
→ molecular mimicry, no vaccine!
→ identical to E. coli K1 capsular antigen!
Meningococcus vaccines
• Suggested for persons with:
– asplenia, complement deficiency, haemoglobinopathy
• Meningitec, Menjugate, NeisVac C
– against serotype C, conjugated (from 2 months)
• Mencevax ACWY
– against A, C, Y and W135 (polysaccharide)
• Menveo
– against A, C, Y and W135, conjugated
– from 11 years of age
Apathogen Neisseriae
• Presence
– oral and nasopharyngeal normal flora→ „N.
pharyngitidis”, pharyngococci
• Cultivation
– easier, normal media, also at RT, fermentate
several sugars
• Species
– N. lactamica, N. sicca, N. mucosa, N. flavescens
• Significance
– diff. diagn.!
– rarely respiratory tract infections, endocarditis
Moraxella genus• Moraxellaceae family
• Gram-negative diplococcus
• oxidase-positive
• culture: white colonies
• M. catarrhalis infections:
– otitis media, sinusitis (see: pneumococcus,
Haemophilus!), bronchitis
– in immunocompromised: sepsis, endocarditis
• M. lacunata : subacute conjunctivitis
• Treatment: β-lactam + enzyme inhibitor,
cephalosporins (II. gen.)
top related