Pseudomonas aeruginosa, also known asPseudomonas aeruginosa(Scientific name: Pseudomonas aeruginosa), first isolated from wound pus by Gersard in 1882, is aGram negative bacteriaAerobic, long rod shaped bacteria only have one-way mobility.It is a kind ofOpportunistic infectionBacteria are also opportunistic infection to plants. After infection, the disease materials such as pus and exudate are green, so it is named.
Pseudomonas aeruginosa, widely distributed in nature and normal human skin, intestines and respiratory tract, is more common in clinicConditional pathogenone of.
Pseudomonas aeruginosa is the scientific name of Pseudomonas aeruginosa. Pseudomonas is composed of pseudo and monas in Greek, which means false unit, and is used to describe bacteria in early microbiology.Aeruginosa is copper green (that is, copper andoxygen, carbon dioxide and waterCopper rust。chemical formulaCu2 (OH) 2CO3), which just expresses the cyan pigment produced by this bacterium.PyocyaninThe biosynthesis ofGroup effectTo regulate, as if full ofCystic fibrosisThe biofilm of Pseudomonas aeruginosa in the patient's lung is the same.
Morphological and cultural characteristics
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The length is about 1.5~3.0 × the width is 0.5~0.8umg.Single, in pairs or occasionally in short chains, filaments can be seen in broth cultures.The mycelium has 1-3 flagella and is active in movement.No spore, capable of formingCapsule。It is easy to be dyed by ordinary dyes,gram-negative。
This bacterium is an aerobic bacteriumculture mediumIt is easy to grow, and the suitable temperature for culture is 35 ℃,PH value7.2.
ordinaryagarForm a smooth, slightly raised, medium and large with regular and wavy edgescolony of bacteria。Due to the production of water-solublePyocyanin(blue-green) andfluorescein(yellow green), so it can infiltrate into the culture medium and make the culture medium yellow green.After a few days, the green color of the culture medium gradually darkens, and the colony surface appearsMetallic luster。
Ordinary broth is even and turbid, and is yellow green.The bacteria in the upper part of the liquid develop more vigorously and form a thick membrane on the surface of the culture medium.However, the mutant strains screened after widely using effective antibiotics often lose their synthetic ability.
Blood agar can be produced by Pseudomonas aeruginosapyocyanase , can dissolve red blood cells, so there is a hemolytic ring around the colony.[1]
Biochemical characteristics
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The ability to decompose protein is very strong, but the ability to ferment sugar is low. It can decompose glucose, gum sugar, milk sugar and mannose without gas or decompositionmalt dust，InulinandRaffinoseMannitol, lactose and sucrose can liquefy gelatin.Decomposition of urea without formationindole，Oxidase testPositive, availableCitric acidSalt.No H2S generation, MR test andVP testAll are negative.
Antigenic structure
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Pseudomonas aeruginosa has cell o antigen and flagella h antigen.One is that o antigen containsendotoxinAnd protoendotoxin protein.Protoendotoxin protein is ahigh polymerLow toxicity and strong immunogenicityProtective antigen, not only exist in differentSerotypePseudomonas aeruginosaPseudomonasOther bacteria of the genus andPneumonia、Escherichia coli、Vibrio choleraeIso-g-bacteria is a good cross protection antigen.The second is lipopolysaccharide, which is closely related to specificity.
Pseudomonas aeruginosa can produce a variety of substances related to toxicity, such as endotoxinExotoxina、elastase、collagenase、Pancreatic peptidaseAmong them, exotoxin a is the most important.Pseudomonas aeruginosa exotoxin a is a heat labile single chainpolypeptide，molecular weightAbout 66000, which can be detoxified into toxoid after formaldehyde or glutaraldehyde treatment, and neutralized by specific antitoxin.The toxicity is strong. After injection into animals, the main target organ liver may have cell swelling, steatosis and necrosis;Other organ diseases include pulmonary hemorrhage and renal necrosis.Mechanism of exotoxin a andDiphtheria toxinSome are similar, that is, eventuallyribosomeupperElongation factor2 (ef-2) inactivation, inhibitionhost cellOfprotein synthesis, but the specific process is different.In addition, exotoxin a and diphtheria toxinprotein structure, immunogenicity, flagellar cells and sensitive animals.
Pseudomonas aeruginosa infection can occur in any part and tissue of the human body, and is commonly found in burns or woundsmiddle ear、Corneal、urethraAnd respiratory tract.Can also causeendocarditis, gastroenteritis, empyema and evensepticemia。The patient can produce specific antibody after infection, which has certain anti infection effect.The use of anti Pseudomonas aeruginosa immune serum can reduce the incidence and mortality of secondary sepsis.
Specimens can be taken from wound exudatesAbscesses, urine, blood, etc.Isolation cultureAccording to colony characteristics, pigments andbiochemical reaction To be identified.If necessary, serological test can be used for diagnosis.
Pseudomonas aeruginosa breeding in some people will make the urine green.
Resistance
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The resistance of this bacterium to chemical drugs is more than ordinaryGram negative bacteriapowerful.1: 2000 Zebita, Dumifen andBromogeramineThe 1:5000 disinfectant can kill it within 5 minutes.0.5-1% acetic acid can also quickly kill them.Some strainssulfa,streptomycin,chloramphenicolSensitive, but easy to produceDrug resistance。Penicillin has no effect on this bacterium, butgentamicinandPolymyxin B, E, aminoglycosides, the third and fourth generation cephalosporins (cefoperazone, ceftazidineCefpirome, cefazolam, etc., the latter two are third line antibiotics, which should be used with caution) and other antibiotics have obvious effects, and some semi syntheticPenicillin antibiotics, such asAloxicillinandPiperacillinIt also has a strong antibacterial effect on Pseudomonas aeruginosa, with an effective rate of about 80%.FosfomycinIt is also effective, but not as effective as the above antibiotics.Combined medication can reduceDrug resistant bacteriaGeneration of strains.Pseudomonas aeruginosa isNosocomial infectionTherefore, disinfection measures play an important role in preventing infection.As there are many types of Pseudomonas aeruginosa and many substances related to virulence, the ideal vaccine is still under development.[1]
② Inhibits the penetration of drugs through the cell wall, thus reducing the concentration of drugs reaching the target
③ Change the target of antibacterial action, so as to avoid the antibacterial effect of antibacterial drugs.
④ Membrane barrier and active efflux limit the drug to reach its target.
⑤ It forms a biofilm, which is composed of polysaccharides.[2]
pathogeny
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Pseudomonas aeruginosa is a kind of immune damaging bacteriaOpportunistic infectionThe pathogen generally affects the lungs and urinary tract, or causes burns, wounds and other blood infections, such as septicemia.Although rare, Pseudomonas aeruginosa can also cause pneumonia.staycontact lensesIncomplete cleaning may also cause corneal infection.In many studies of pneumonia related to respirators, Pseudomonas aeruginosa is one of the bacteria that needs to be isolated.Pyocyanin - a toxic metabolite of blue-green, namely Pseudomonas aeruginosaPathogenic factorAnd can makecaenorhabditis elegans Death, but some studies indicate that salicylic acid can inhibit the production of pyocyanin.10% atnosocomial infectionAll of the cases are caused by Pseudomonas aeruginosa.The lungs of cystic fibrosis patients were the first group to be infected with Pseudomonas aeruginosa.In the absence of proper treatment, it is also one of the bacteria that cause dermatitis.It also causesBurn infectionThe most common bacteria.
Pseudomonas aeruginosa is naturally resistant to most antibiotics, and can quickly produce drug-resistant mutations.Generally combined with two antibiotics（Aminoglycoside antibiotics，β - lactam antibioticsorQuinolonesAntibiotics) use aggressive antimicrobial treatment.General treatment should be assisted by laboratory sensitivity, rather than selecting the type of antibiotics based on experience.If antibiotics have been used, their reproduction must be understood as much as possible and the effectiveness of antibiotics must be reviewed frequently.
Antibiotics that are effective against Pseudomonas aeruginosa include:
Except fluoroquinolone, all the above antibiotics must be used by injection.Therefore, the use of fluoroquinolone is strictly prohibited in some hospitals to prevent Pseudomonas aeruginosa from developing corresponding drug resistance.[2]
