Pseudomonas aeruginosa Ιωαννης Γ. Ρούτσιας, Επικ. Καθηγητης Ανοσολογιας/Μικροβιολογιας
Pseudomonas aeruginosa gram-negative non-sporing bacteria Obligate Aerobe, mostly saprophytic Motile Commonly found in the environment (water, air, soil) At any moist location Common cause of nosocomial infections
P. aeruginosa (ευκαιριακό παθογόνο) Extremely broad host spectrum Hardly any infections in the normal human host Severe immunodeficiencies and medical devices predispose the patients to P. aeruginosa infections Broad spectrum of clinical symptoms Urinary tract infections Pulmonary infections Soft tissue infections Sepsis Bone and joint infections Endocarditis
Diseases (Pathogenicity) Community Hospital Eye Ear Skin UTI RTI GIT CNS Suppurative (πυωδης) Otitis Nosocomial infection Keratitis and Endophthalmitis Otitis externa and Otitis media Burns infection, wound sepsis Ecthyma gangrenosum Cystitis (catheterized) Pneumonia (ventilation / tracheostomy) Infantile (βρεφική) diarrhea Meningitis brain abscess (iatrogenic)
P. aeruginosa & λοιμώξεις P. aeruginosa infections are of particular concern for Cystic fibrosis patients Burn patients Cancer cytotoxic drugs Hospitalised patients Case mortality rate for patients infected with P. aeruginosa approaches 50%
Νοσοκομειακές λοιμώξεις Fourth most common isolated nosocomial pathogen accounting for approx. 10 % of all hospital acquired infections. Patient-to-patient spread and direct patient contact with environmental reservoirs respiratory equipment, food, sinks, taps
Διάγνωση λοίμωξης από P. aeruginosa Isolation and lab identification of the pathogen P. aeruginosa grows well on most laboratory media Identified on the basis of its: Gram morphology, inability to ferment lactose, a positive oxidase reaction, its characteristic odor (οσμή), Green pigments (Pyocyanin, Flurescein) its ability to grow at 42 C. Fluorescence is helpful in early identification of P. aeruginosa colonies and may also help identify its presence in wounds.
Pyocyanin (blue-green) Fluorescein (green-yellow, fluorescent)
Δοκιμασία κινητικότητας
Θεραπεία των λοιμώξεων από P. aeruginosa P. aeruginosa is frequently resistant to many commonly used antibiotics. Antipseudomonad beta lactam Aminoglycoside Fluoroquinolone To archive synergy a combination of e.g. gentamicin and carbenicillin is frequently used. No vaccines so far
Μηχανισμοί παθογονικότητας Adhesion (Προσκόληση) Pili (κροσσοι), flagella (μαστίγια) and fimbriae (φιμπριες) Invasion (Διείσδυση) Extracellular enzymes and toxins (proteases, elastase, phospholipases, rhamnolipids, Exotoxin A) rhamnolipids: glycolipids that kill epithelial cells, kill polymorphonuclear leukocytes and macrophages and inhibit phagocytosis Exotoxin A blocks protein synthesis by ADP ribosylation of elongation factor 2, thereby triggering cell death Dissemination (Διασπορά) Leukocidin inhibits neutrophils und leukocytes LPS (Endotoxin) Protection Capsule (έλυτρο)
Interbacterial Communication
Quorum Sensing (Διακυτταρική επικοινωνία βακτηρίων) in P. aeruginosa McKnight et al, 2000
Cooperative traits and coordinated behavior of bacteria
Adaptation and survival is facilitated by diversity
Small colony variants (SCV)
SCVs of P. aeruginosa in CF Slow growing subpopulations (3% of the P. aeruginosa positive sputum specimens) SCVs exhibit an increased resistance towards a broad spectrum of antimicrobial agents The recovery of SCV correlates with parameters revealing poor lung function and an inhalative antimicrobial therapy Fast growing revertants REV can be isolated from the SCV population
Auto-aggregation in liquid cultures
CupA encoded fimbria expression in P. aeruginosa M. Rohde, GBF Braunschweig
Molecular Mechanisms controlling the conversion to a SCV biofilm phenotype
Bacterial Biofilms
Biofilms in the environment
Catheter associated biofilms
Chronic biofilm infections
Despite even intensified antibiotic therapy, no eradication of chronic P. aeruginosa infections of the cystic fibrosis lung
Cystic fibrosis (Κυστική ίνωση) Most common life-threatening inherited genetic disorder in the Caucasian population Mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene CFTR: ρυθμιστική πρωτεΐνη που ελέγχει την διέλευση χλωρίου διαμέσου των μεμβρανών των επιθηλιακών κυττάρων διαφόρων οργάνων του σώματος όπως των πνευμόνων, του παγκρέατος, των ιδρωτοποιών αδένων και του εντέρου Περίπου 1 στα 2000 2500 παιδιά εκτιμάται ότι γεννιούνται κάθε χρόνο στην Ελλάδα με κυστική ίνωση, ενώ το 4 5% του πληθυσμού θεωρείται ότι είναι φορείς. Life expectancy: Until the 1930s: the life expectancy of a baby with CF was only a few months, in the 1980s, most deaths from CF occurred in children and teenagers. Today with improved treatments, nearly 40 percent of the CF population is aged 18 and older, for a person with CF the median age of survival is nearly 37 years. Cystic Fibrosis affects a number of organs in the body, cycles of infection and inflammation lead to a progressive deterioration of lung function.
Cystic fibrosis (Κυστική ίνωση) Μεταλλάξεις στο γονίδιο CHTFR προκαλούν μειωμένη παραγωγή ή λειτουργικότητα της πρωτεΐνης με αποτέλεσμα στο επιθήλιο των προσβαλλομένων οργάνων να παράγεται παχύρρευστη κολλώδης βλέννα η οποία αποφράσσει τους πόρους των αδένων με συνέπεια την προοδευτική καταστροφή του ιστού των οργάνων (ίνωση) και την τελική ανεπάρκεια τους. Τα άτομα με κυστική ίνωση έχουν αφύσικα υψηλά επίπεδα άλατος στον ιδρώτα Υψηλά επίπεδα άλατος εμποδίζουν να δράσουν τα φυσικά αντιμικροβιακά πεπτίδια (defensins) ευνοείται η ανάπτυξη της Ψευδομονάδας
Chronic infection of the Cystic Fibrosis lung
Why is traditional antimicrobial therapy ineffective against biofilm bacteria?
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