PSEUDOMONAS• A large group of aerobic, non sporing gram negative bacteria motile by polar flagella• Found I nature water, soil, other moist environments• Some of them are pathogenic to plants• Creation of new genera such as Burkholderia. StenotrophomnonasDR.T.V.RAO MD 2
GENERAL CHARACTERISTICS- Widely distributed in soil and water- Gram negative rods- Aerobic- Motile- Produce water-soluble pigments• Opportunistic pathogensDR.T.V.RAO MD 3
MORPHOLOGY• They are slender gram negative bacillus, 1.5 – 3 microbes x 0.5 microns• Monoflgellar ?• Non capsulated but many strains have mucoid slime layer• Isolates from Cystic fibrosis patients have abundance of extracellular polysaccharides composed of alginate polymers• Escape the defence mechanisms by loose capsule in which micro colonies of bacillus are enmeshed and protected from host defences.DR.T.V.RAO MD 4
P. aeruginosa Forms round colonies with a fluorescent greenish color, sweet odor, and -hemolysis. Pyocyanin- nonfluorescent bluish pigment; pyoverdin- fluorescent greenish pigment; pyorubin, and pyomelanin Some strains have a prominent capsule (alginate).Identification of P. aeruginosa is usually based on oxidase testand its colonial morphology: b-hemolysis, the presence ofcharacteristic pigments and sweet odor, and growth at 42 oC.
CULTURAL CHARACTERS• Obligate aerobe, but grow anaerobically if nitrate is available• Growth occurs at wide range of temperatures 6-42 c the optimum being 37 c• Growth on ordinary media producing large opaque irregular colonies with distinctive musty mawkish or earthy smell.• Iridescent patches with metallic sheen are seen in cultures on nutrient agar.• In broth forms dense turbidity with surface pellicle.DR.T.V.RAO MD 6
Characteristics of Pseudomonas aeruginosaMotile (by single or multiple polar flagella) gram-negative rodsObligate (strict) aerobes (most strains)Oxidase (usually) and catalase positiveNonfermentative chemoheterotrophic respiratory metabolismMinimal nutritional reqts.; Many organic compounds used as C and N sources, but only a few carbohydrates by oxidative metabolism • Glucose used oxidatively • Lactose negative on MacConkey’s agar DR.T.V.RAO MD 7
PIGMENT PRODUCTIONSome strains produce diffusible pigments: • Pyocyanin (blue); fluorescein (yellow); pyorubin (red)P. aeruginosa produces characteristic grape-like odor and blue-green pus & coloniesBroad antibiotic resistanceDR.T.V.RAO MD 8
BIOCHEMICAL REACTIONS• Oxidative and Non fermentative• Glucose is utilized oxidatively• Indole, MR and VP and H2 S tests are negative• Catalase, Oxidase, and Arginine tests are positiveDR.T.V.RAO MD 9
TYPING AND IMPORTANCE• Important cause of Hospital Infections• Important for epidemiological purpose• Serotyping• Bacteriocins typing• Pyocyanin• Aeruginosin typing• Restriction endonuclease typing with pulsed gel electrophoresisDR.T.V.RAO MD 10
RESISTANCE• Killed at 55oc in on 1 hour• High resistance to chemical agents• Resistance to quaternary ammonium compounds.Chlorxylenol• Resistant to Hexchlorophenes• Grows also in antiseptic bottles• Dettol as cetrimide as selective medium• Sensitive to acids silver salts, beta glutaraldehydeDR.T.V.RAO MD 11
WHAT ANTIBIOTICS TO USE• Aminoglycosides• Gentamycin, Amikacin, Cephalosporins• Cefotaxime. Ceftazidime. Ofloxacin,• Piperacillin, ticarcillin• Local application, colistin, polymyxinDR.T.V.RAO MD 12
PATHOGENICITY• Blue pus• Causing the nosocomial infection• Suppurative otitis• Localised and generalised infections• Urinary tract infection after catheterization• Iatrogenic meningitis• Post tracheostomy pulmonary infectionsDR.T.V.RAO MD 13
P. aeruginosaPathogenesis and ImmunityThis organism is widely distributed in natureand is commonly present in moist environmentsin hospitals. It is pathogenic only whenintroduced into areas devoid of normaldefenses, e.g., 1. Disruption of mucous membrane and skin. 2. Usage of intravenous or urinary catheters. 3. Neutropenia (as in cancer therapy).
P. aeruginosaPathogenesisAntigenic structure, Proteasesenzymes, and toxins Serine protease,Pili and nonpilus adhesins. metalloprotease and alkalineCapsule (alginate, glycocalyx): protease cause tissueseen in cultures from patients damage and help bacteriawith cystic fibrosis. spreadLPS- endotoxin, multiple Phospholipase C: a hemolysinimmunotypes. Exotoxin A: causes tissuePyocyanin: catalyzes necrosis and is lethal for animalsproduction of toxic forms of (disrupts protein synthesis);oxygen that cause tissue immunosuppressive.damage. It also induces IL-8production. Pyoverdin: a Exoenzyme S and T: cytotoxic tosiderophore. host cells.
PATHOGENESIS AND IMMUNITY• P. aeruginosa can infect almost any external site or organ.• P. aeruginosa is invasive and toxigenic. It attaches to and colonizes the mucous membrane or skin, invade locally, and produces systemic diseases and septicemia.• P. aeruginosa is resistant to many antibiotics. It becomes dominant when more susceptible bacteria of the normal flora are suppressed.DR.T.V.RAO MD 16
WHO IS MORE SUSCEPTIBLE TO INFECTION• This bacterium is of particular concern to individuals with cystic fibrosis who are highly susceptible to pseudomonas lung infections. Pseudomonas aeruginosa is also of grave concern to cancer and burn patients as well as those people who are immunocompromised. The case fatality rate for individuals infected with Pseudomonas aeruginosa approaches 50 percent.DR.T.V.RAO MD 18
PSEUDOMONAS AND CYSTIC FIBROSIS • Pseudomonas aeruginosa is the most frequently encountered lung pathogen in patients with cystic fibrosis (CF). Following initial, often intermittent, episodes of infection, it becomes a permanently established component of the chronically infected lung in more than 80% of patients and confers an adverse prognosisDR.T.V.RAO MD 19
INFECTION OF EQUIPMENTS• Respirators• Endotracheal tubes• Can be Infected• All equipments to be sterilizedDR.T.V.RAO MD 20
PSEUDOMONAS AND URINARY TRACT INFECTIONS• Pseudomonal UTIs are usually hospital-acquired and are associated with catheterization, instrumentation, and surgery. These infections can involve the urinary tract through an ascending infection or through bacteriuic spread. In addition, these infections are a frequent source of bacteraemia. No specific characteristics distinguish this type of infection from other forms of UTI.DR.T.V.RAO MD 21
TOXINS AND ENZYMES IN PSEUDOMONAS• Toxic extracellular products in culture filtrates• Exotoxin A and S• Exotoxin A acts as NADase resembling Diphtheria toxin• Proteases,elastatese hemolysins and enterotoxin• Slime layer and BiofilmsDR.T.V.RAO MD 22
PSEUDOMONAS AERUGINOSA AN IMPORTANT OPPORTUNISTIC PATHOGEN• Pseudomonas aeruginosa is an opportunistic pathogen, meaning that it exploits some break in the host defences to initiate an infection. In fact, Pseudomonas aeruginosa is the epitome of an opportunistic pathogen of humans. The bacterium almost never infects uncompromised tissues, yet there is hardly any tissue that it cannot infect if the tissue defences are compromised in some mannerDR.T.V.RAO MD 23
P.AEROGINOSA IS AN OPPORTUNISTIC PATHOGEN• P,aeroginosa is an opportunistic pathogen. It rarely causes disease in healthy persons. In most cases of infection, the integrity of a physical barrier to infection (eg, skin, mucous membrane) is lost or an underlying immune deficiency (eg, neutropenia, immunosuppression) is present. Adding to its pathogenicity, this bacterium has minimal nutritional requirements and can tolerate a wide variety of physical conditionsDR.T.V.RAO MD 24
PSEUDOMONAS PROMINENT HOSPITAL ACQUIRED INFECTIONS• It causes urinary tract infections, respiratory system infections, dermatitis, soft tissue infections, bacteraemia, bone and joint infections, gastrointestinal infections and a variety of systemic infections, particularly in patients with severe burns and in cancer and AIDS patients who are immunosuppressed.DR.T.V.RAO MD 25
DIAGNOSIS OF P.AEROGINOSA INFECTION• Diagnosis of P,aeroginosa infection depends upon isolation and laboratory identification of the bacterium. It grows well on most laboratory media and commonly is isolated on blood agar or eosin-methylthionine blue agar. It is identified on the basis of its Gram morphology, inability to ferment lactose, a positive oxidase reaction, its fruity odour, and its ability to grow at 42°C. Fluorescence under ultraviolet light is helpful in early identification of P.s aeruginosa colonies. Fluorescence is also used to suggest the presence of P. aeruginosa in wounds.DR.T.V.RAO MD 26
IDENTIFICATION WITH CHROMAGARPseudomonas sp. develop as easilydistinguishable blue-green colouredcolonies, clearly visible under normallighting conditions. Other bacterialspecies are inhibited or givecolourless colonies. Pseudomonasaeruginosa, Pseudomonasfluorescens, Pseudomonas putidaand Pseudomonas fragilis all givetypical blue-green colony colourationand can be studied directly byserotyping or biochemical methods.DR.T.V.RAO MD 27
LABORATORY IDENTIFICATION OF DIAGNOSIS OF P.AEROGINOSA INFECTIONS• Diagnosis of P. aeruginosa infection depends upon isolation and laboratory identification of the bacterium. It grows well on most laboratory media and commonly is isolated on blood agar or eosin-methylthionine blue agar. It is identified on the basis of its Gram morphology, inability to ferment lactose, a positive oxidase reaction, its fruity odour, and its ability to grow at 42° C. Fluorescence under ultraviolet light is helpful in early identification of P. aeruginosa colonies and may also help identify its presence in wounds.DR.T.V.RAO MD 28
TREATING PSEUDOMONAS INFECTIONS• Combined antibiotic therapy is generally required to avoid resistance that develops rapidly when single drugs are employed. Avoid using inappropriate broad-spectrum antibiotics, which can suppress the normal flora and permit overgrowth of resistant pseudomonads.DR.T.V.RAO MD 29
PSEUDOMONAS AERUGINOSA A RESISTANT PATHOGEN• Pseudomonas aeruginosa is frequently resistant to many commonly used antibiotics. Although many strains are susceptible to gentamicin, tobramycin, colistin, and amikacin, resistant forms have developed. The combination of gentamicin and carbenicillin is frequently used to treat severe Pseudomonas infections. Several types of vaccines are being tested, but none is currently available for general use.DR.T.V.RAO MD 30
P. aeruginosaPrevention and ControlPseudomonas spp. normally inhabit soil, water, and vegetationand can be isolated from the skin, throat, and stool of healthypersons.Spread is mainly via contaminated sterile equipments andcross-contamination of patients by medical personnel.High risk population: patients receiving broad-spectrumantibiotics, with leukemia, burns, cystic fibrosis, andimmunosuppression.Methods for control of infection are similar to those for othernosocomial pathogens. Special attention should be paid to sinks,water baths, showers, hot tubs, and other wet areas.
• Programme created by Dr.T.V.Rao MD for Medical and Paramedical Students • Email • firstname.lastname@example.orgDR.T.V.RAO MD 32