Pseudomonas Bacteria PDF

Gram Negative Rods PSEUDOMONAS  Characteristics of Pseudomonas Gram-negative bacilli belonging to Pseudomonadaceae, Motile, Capsulated "Polysaccharide capsule" Aerobic, Non fermentative, using carbohydrates through respiratory metabolism, breakdown glucose by oxidation. Oxidase pos...

Gram Negative Rods PSEUDOMONAS  Characteristics of Pseudomonas Gram-negative bacilli belonging to Pseudomonadaceae, Motile, Capsulated "Polysaccharide capsule" Aerobic, Non fermentative, using carbohydrates through respiratory metabolism, breakdown glucose by oxidation. Oxidase positive (It is used to differentiate them from the Enterobacterales) Catalase positive. very simple nutritional requirements - non fastidious. The most important pathogenic organism is P. aeruginosa Optimum temperature is 37 C, and it is able to grow at 42 ºC resistant to high concentrations of salts, dyes, weak antiseptics, and many antibiotics Common inhabitants of soil, water, GIT Pseudomonas aeruginosa Ubiquitous – Soil, decaying organic matter, vegetation, water – Hospital environment Moist reservoirs, food, cut flowers, sinks, toilets, floor mops, respiratory therapy & dialysis equipment – EVEN “disinfectant solutions” Simple growth requirements (can even grow in distilled water!!!!!!!)  P. aeruginosa produce two types of soluble pigments: – Pyoverdin or fluorscein: It is yellow-green pigment and fluorescent – Pyocyanin: It is a blue-green pigment and non-fluorescent – Some strains produce the dark red pigment pyorubin Pyocyanin and pyorubin Pyoverdine  Cultural Characteristics P. aeruginosa on Cetrimide agar Gram Stain of Pseudomonas P. aeruginosa on Nutrient agar  Pseudomonas /Pathogenesis & Immunity Multiple virulence factors – Structural components: adhesins (e.g., flagella, pili, LPS, capsule) – Toxins & enzymes, pigments: exotoxin A, pyocyanin, pyoverdin, elastases, proteases, phospholipase C, exoenzymes S and T – Antibiotic resistance Adhesins: Adherence of P. aeruginosa to host cells is mediated by pili and non-pilus adhesins. Polysaccharide capsule: also known as mucoid exopolysaccharide, alginate coat or glycocalyx. The capsule protects the organism from phagocytosis and activity of antibiotics. Endotoxin: Major cell wall antigen in P. aeruginosa, as it is in other gram negative rods.  Pyocyanin: catalyzes the production of superoxide and hydrogen peroxide, toxic forms of oxygen. Exotoxin A: It is believed to be one of the most important virulence factor of pathogenic P. aeruginosa. This toxin disrupts protein synthesis by blocking peptide chain elongation in eukaryotic cell. Exoenzymes S and T: They are extracellular toxins produced by P. aeruginosa. When the type III secretion system (T3SS) introduces the proteins into their target eukaryotic cells, epithelial cell damage occurs, facilitating bacterial spread, tissue invasion and necrosis. Elastases: Two enzymes LasA (serine protease) and LasB (zinc metalloprotease) degrade elastin, resulting in damage to elastin-containing tissues and producing the lung paranchymal damage and spread to skin causing black necrotic lesions or hemorrhagic lesion (ecthyma gangrenosum).  Alkaline protease: Contributes to tissue destruction and spread of P. aeruginosa. It also interferes with the host immune response. Phospholipase C: heat labile hemolysin that breaks down lipids and lecithin, facilitating tissue destruction. Antibiotic resistance: mutations of porin proteins, prevent penetration of antibiotics to the bacterial cell. Virulence Factors Associated with Pseudomonas aeruginosa  Pseudomonas / Clinical diseases Pulmonary infections (cystic fibrosis) Burn wound & other skin & soft tissue infection UTI (Urinary tract infections) External otitis Eye infection (contaminated contact lens cleaning fluids) Bacteremia & endocarditis  Pseudomonas /Diagnosis & Identification Culture – Simple media – beta hemolysis, – green pigment, – grapelike odor Identification – Colonial morphology : colony size, hemolysis, pigmentation, odor – Biochemical tests: Positive oxidase test (e.g., positive oxidase reaction)  Pseudomonas / Treatment Combined use of effective antibiotics (e.g., aminoglycoside and β-lactam antibiotics) frequently required; monotherapy is generally ineffective and resistant strains can be developed. Hospital infection-control efforts should concentrate on preventing contamination of sterile medical equipment and nosocomial transmission. P. aeruginosa also produces a number of different β- lactamases, that can inactivate many β-lactam antibiotics (e.g., penicillins, cepha losporins, and carbapenems): treatment problem because of limited antibiotic choices.  Acinetobacter Gram negative coccobacilli resemble Enterobacteriaceae in growth pattern and colonial morphology Incapable of fermenting carbohydrates or reduce nitrates. Appear frequently as skin and respiratory colonizers Frequently contaminate wet objects including soaps and disinfectant solutions. Pneumonia, urinary tract and soft tissue are the most common infections Nosocomial respiratory infections are traced to contaminated inhalation therapy equipment’s ( ventilator) whereas bacteremia to infected intravenous catheters. Due to frequent resistance to penicillins, cephalosprins and some aminoglycosides treatment is difficult and required prior sensitivity testing.  Vibrio Vibrio cholerae, Vibrio parahaemolyticus Vibrio vulnificus  The General Characteristic of Vibrio Gram negative, Slightly convoluted, hard-bodied They are very motile with one flagellum Oxidase(+), Gelatinase (+), Catalase (+), Indole (+) They never form urease and H2S Can grow on a variety of simple media within a broad spectrum temperature range (14- 40 oC). V. cholerae can grow in the absence of salt, most other species that are pathogenic in humans require salt. Vibrios tolerate a wide range of pH but are susceptible to stomach acids.  Vibrio cholerae , It is a rod, comma ( ) shape. A few can be seen as S, C together. very motile with a single polar flagellum, whose natural habitat is usually salt or fresh water. growth easy in alkali medium high pH(8.5-9.5) weak against acid melt gelatin and coagulant serum Have musinase and RDE( receptor destroying enzyme) Vibrio cholerae appears as a non lactose fermenter V. cholerae enters the human body through ingestion of contaminated food or water. The bacterium enters the intestine, imbeds itself in the villi, replicates and releases cholera toxin. Vibrio cholerae's light and electron microscopy images ❖ V.cholerae grow best on Thiosulphate-citrate-bile- sucrose(TCBS)agar on which it produce yellow colonies that are readily visible against the dark green background of the agar. Antigenic structure H antigen LPS (O) antigen Three major subgroups; 1. V. cholerae O1 2. V. cholerae O139 3. V. cholerae non-O1 (O2-O138) Resistance Sensitive to heat, disinfectant, dryness and acids 15 min at 55 ° C. also die. in 5% phenol. also die in 2 minutes. Sensitive against most of the chemotherapeutics (chloramphenicol, tetracycline, gentamycin, ampicillin) Virulence Motility Pilus Hemaglutinin Musinase Capsule Cholera toxin  The mechanism of action of cholera toxin Bacteria attach to upper intestine via pili and subsequently colonize. Cholera enterotoxin – 1 A subunit – 5 B subunits B subunits bind to a GM1 ganglioside receptor on the mucosal cell to allow entry of the A subunit A subunit Overactivates Adenylate Cyclase (Gs protein) Hypersecretion of Water, Chloride and other  Clinic of cholera The incubation period is 2-3 days. The disease starts with sudden vomiting and diarrhea. The feces is first fecaloid, then the rice water look and fishy smell. In 5-12 hours; Urine is diminished, it can be an anuria. There is no fever, but cyanosis (Cyanosis is defined as the bluish or purplish discolouration of the skin or mucous membranes due to the tissues near the skin surface having low oxygen saturation). There are painful cramps in the arms and legs. Scaphoid abdomen but is soft. The reflexes are diminished. As the disease progresses, heart sounds are weak. With acidosis and coma, death occurs in a few days.  Diagnosis Vibrio can remain alive for 14 days in room temperature in peptone water and 21 days in plastic bag method. 1d From Fresh stool or 4-6 hours peptone water cultivation + 1d. 0 group serum is match. Aggl. The preparation prepared from the material is examined by fluorescent antibody technique. It is not used in the first instance. Serological diagnosis with two serially serums is useful for follow-up. Vibrio parahaemolyticus The first was found by Fujino in food poisoning caused by eating of seafood in Japan. Halophilous It is seen with severe vomiting and abundant watery diarrhea 6-20 hours after food intake. It usually heals in 2-3 days. Diagnosis: from the stool. V. vulnificus It is a particularly virulent species of Vibrio responsible for rapidly progressive wound infections after exposure to contaminated seawater and septicemia after consumption of contaminated raw oysters. The antimicrobial therapy is important especially immunocompromised patients.  Treatment, prevention and control of Vibrio Patients with cholera must be promptly treated with fluid and electrolyte replacement. Antibiotic therapy, although of secondary value, can reduce toxin production and more rapidly eliminate the organism. Doxycycline or tetracyline is the drug of choice for adults. V. parahaemolyticus gastroenteritis is usually a self limited disease, although antibiotic therapy can be used in addition to fluid and electrolyte therapy in patients with severe infection. V. vulnifucus wound infections and septicemia must be promptly treated with antibiotic.