Transcript Bez nadpisu - Comenius University

Practical 7 - Pseudomonas, Bordetella,
Bacillus
Hospital infections
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• Whooping cought
• Antrax a bioterorismus
• Microscopy - sc. Gram - Ps. aeruginosa, Bacillus anthracis,
Bacillus cereus, sc.Wirtz Coonklin Bac. anthracis
• Cultivation Ps. aeruginosa on blood agar and Endo,
Bordetella pertussis on Bordet Gengou, B. anthracis a B.
cereus on blood agar
• Biochemical properties of Ps. aeruginosa
• Ascoli thermoprecipitation
• Cultivation of B. pertussis
• ATB therapy of Ps. aeruginosa
Hospital - nosocomial infections
• Hospital infection - infection, that arises in connection to
hospitalisation or to diagnostical, therapeutic or preventive processes.
I does not necessary have to present during the hospitalisation and not
every infection arising during hospitalisation is nosocomial
• Risk factors - age,accompanying diseases, surgical processes therapy ATB, imunosupression, irradiation, not vital reservoire - indwelling
catheters)
• Microbes
• Ways of transmission - in direct (inhalation, ingescion, inoculation) ,
direct (contact of infected skin or mucous membrane with healthy)
• Prevetion - organisation of health process, construction, food supply,
health process technics, asepsis and antisepsis, nursery approches,
isolation, monitoring, surveillance, role of microbiologickal
laboratory)
• ATB therapy
Role of microbes in hospital infections
• Staphylococcus aureus - problems of per secundam healing wounds
(70 ies). Virulence, colonisation capacitiy, resistence - MRSA methicilin resistent staphylococcus aureus (80 ies)
• G-rods (60% of HI) - urinary tract infections, respiratory infections,
wound infection, GIT
• Opportunistic pathogens - Ps. aeruginosa (Hospital environmente –
food, cut flowers, water, toels, mops, respiration devices, desinfection
solutions. Persistent carriage in less than 6% helathy, 38% in
hospitalised, 78% imunocompromised) and other non fermenting Grods - Acinetobacter, Stenotrophomonas maltophilia, Burkholderia
cepacia… - present in environmentí (Legionella pneumophila climatisation)
• PK negative staphylococci - colonisation of plastic material of
indwelling catheters
• Viruses - blood borne infection agenses HIV, VHB, VHC, CMV….
ATB therapy in hospital infections
• Overuse of ATBe - resistence and multiresistence (selection pressure
of ATB and transmission in hospital environment), toxic side effects,
economic burden, deterioration of physiological microflora
• Racional indication - preventive in spread of HI
• Prophylaxis - oriented to anaerobe infectione - perioperative
preparation for GIT and UGT surgery, in instrumental examination of
patients with bacteriuria
• ATB surveys - monitoring of ATB susceptibility
• Restrictive policy - time restricted contraindication of some ATB
• Rotation of atb - periodical changes of used - decreasing of selection
pressure
• Combination of atb - agains possible resistent mutnants, broader
antimicrobial spectrum
Whooping cought
• Clinical signs
Inhalation of infectious droplets Patogenesis – exposition to bacteria
and attachment to cylindric epitelium of bronchial stroma, production
of toxinu and of tissu destruction + systemic toxicity
– catharral phase (1-2 weeks) - sy influenza disease
– paroxysmal phase (2- 4 weeks) - destruction of epitel –
paroxysmus of cought – restriction of respiratory ways, vomiting,
lymfocytosis
– reconvalescence – decrease of paroxysmi - secundary complication
Prevention Whool cell vaccine - neurological? ( combination with
diphtheric, tetanic and Hib or VHB vakccine).
Acellular vaccine – imunogenicity ?
Therapy - supporting, nursing, survey, ATB do not necessary have to
ameliorate the state – intoxication and destruction of epithel - ERY eradiction of bacteriae, reduction of infectiousity
Anthrax a bioterorismus
• Very virulent (toxin)
• Inhalation, ingescion and contact - spread by air aerosol, bombes, water
• Resistent - broad thermal interval (14-42*C).
Spores - resistent to drying
Mikroscopy
• Mikroscopy - sc. Gram - Ps. aeruginosa,: G- huge rod
• G+ huge rod , long chains of rods with centrally located
spores: Bacillus anthracis. In smear from tissue - not spores.
• Bacillus cereus: G+ rod without capsule, motile
• - sc. Wirtz Coonklin (practicals 4 ST) - detection of spores
of Bacillus anthracis
Cultivation
• Ps. aeruginosa on blood agar - mucous gray colonies with
methal lood and pigment and characteristic smell Production
of diffusibile pigment - pyocyanin and of capsule
• B. anthracis on blood agar- aerobe, facult. anaerobe rod,
t.: 14- 45*C, small graish adherent colonies lining in paralel
way - growing in picture of caput medusae, colonies with
wave edges. Encapsulated colonies are soft, non
encapsulated are rough, Older colonies growing in aerobe
environment contain spores - dry wrinkled look. Growth on
medium with PNC - chain of pearls
• B. cereus on blood agar - not producing capsule, gray
colonies
Cultivation of Bordetella
pertussis
• Very difficult, aerobe, prolonged cultivation,
production of toxic metabolites, must be
absorbed with active charcoal, high
concentration of blood and ATB - Bodette
Gengou medium
• Plates with high level of agar, ensured agains
drying
• Transparent colonies (B. parapertussis - brown
pigment)
Biochemical properties of
Ps.aeruginosa
• Minimal nutrition requirements, thermotolerant 4*- 42* C, rezistent
to ATB and desinection
Nonfermenting – cytochromoxidase – dif.dg. (COX test), Hajn tube
medium - without change - red - detection of pigment and smell.On
transparent media - green pigment
• Oportunistic: factors of virulence: Pilli - adherence
Polysacharid capsule – antifagocytosis, attachment, Endotoxin – LPS sepsis
Exotoxin A – most important, blocs proteosynthesis of eukaryotic cells Alkalic
protease – destruction of tissu Phospholipase C – destruction of lipids and lecithin,
destruction of tissue
Ascoli termoprecipitation reaction
• Detection of antigens extracted by heat directly from
biological material by antibodies in agar
• Factors of pathogenicity - capsule and toxins - both have
antifagocytic properties, toxin - effect on CNS, leu.
Fagocyted spores are not destroyed
• Toxin - 3 subunits : EF - oedematogenous factor, LF lethal factor, protective antigen PA
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EF+LF - not toxic effect
LF+PA - lethal, not oedematogenous
EF+PA - only len oedem
EF+PA+LF - maximal toxicity
PA - most immunogenic
EF, LF solely not immunogenic
EF+PA, EF+LF, LT+PA, EF+LF+PA - immunogenic
B.pertussis - sampling and cultivation
• Sample from nasopharynx - on bound wire, humidity. Coughing plates
- overgroth of contaminating flora - (Blood agar + active charcoal
+ATB, or Bordette Gengou)
Bordetella pertussis – nutritionally very requiring, virulent.
Pertussic toxin – 2 subunits: A (active) multiple biological effects,
B(binding) Dermonecrotic toxin – vasoconstriction, tissue
destructione Filamentous haemaglutinin – attachement,
hemagglutination -protective Ab, Adenyl cyclase - toxin – interference
with immunity cells (inhibition), Tracheal cytotoxin – cilliostasis, LPS
- endotoxin
Laboratory diagnosis Sensitiveto drying, fat acid in cotton of
sampling devices are toxic, not living in common transport media,
direct innoculation on Bordet Gengou plate. Humid chamber prolonged incubation – 7 days
Serology -Agglutination: patient serum + Ag B. pertussis - 2 samples
in 14 days interval, 4 fold increase of titer, conversion from negat to
pozit
ATB susceptibility of pseudomonas
• Therapy - Frustrating – immunocompromised defence of patient,
typical ATB rezistence
induction of ATB inactivating enzymes
resistence transmission via plasmids
Isolation without signs of infection is not indication for ATB
therapeutic intervention
• Aminoglycosides – useless in the place of infection, acid environment
in abscess
Combination of ATB – beta lactams + aminoglycosides,
Meronem, Imipenem, Sulperason, Cefoperason
• Preventive approaches - Interruption of contamination of steril
materials and cross contamination. Decontamination of fits and and
tubes and catheters and environment - nosocomial strains in intensive
care units. Broad spectrum ATB use - very carefully - suppression of
normal flora and overgrowth of resistent bacteria and mutants