A cystic fibrosis patient presented with an episode of pneumonia. On sputum culture, mucoid colonies of Pseudomonas were seen. What does this indicate?
Ans. a. It formed a biofilm on bronchial walls {Ref: Harrison 19/e p145e-4, p166e-1 18/e p1016)Pseudomonas aeruginosa growing on the bronchial mucosa during chronic infection, staphylococci and other pathogens growing on implanted medical devices, and dental pathogens growing on tooth surfaces to form plaques represent several examples of microbial biofilm growth associated with human disease.'A topic of major interest is the ability of many bacterial fungal, and protozoal species to grow in multicellular masses referred to as biofilms. Growth in biofilms leads to altered microbial metabolism, production of extracellular virulence factors, and decreased susceptibility to biocides, antimicrobial agents, and host defense molecules and cells. Pseudomonas aeruginosa growing on the bronchial mucosa during chronic infection, staphylococci and other pathogens growing on implanted medical devices, and dental pathogens growing on tooth surfaces to form plaques represent several examples of microbial biofilm growth associated with human disease. It is increasingly accepted that this mode of growth contributes to microbial virulence and induction of disease and that biofilm formation can also be an important factor in microbial survival outside the host, promoting transmission to additional susceptible individuals. - Harrison 18/e p1016'Pseudomonas aeruginosa: Non-capsulatedQ but many strains have mucoid slime layer of alginateQ particularly from patients of cystic fibrosis.'Pseudomonas aeruginosaGram negative, obligate aerobicQ, motile bacilli with polar flagellaQ. differentiated from enteric gram negative bacilli by its ability to oxidize indophenol and inability to ferment lactoseNon-eapsulatedQ but many strains have mucoid slime layer of alginateQ particularly from patients of cystic fibrosisCulture and growth characteristics:Grows well at 37-42degC on ordinary media, growth at 42degC helps differentiate it from other pseudomonas species Selective media: Cetrimide agarQPseudomonas PigmentsPyocyanin: bluish green pigment produced only by P. aeruginosaQ. It inhibits growth of many other bacteriaFluorescein: greenish-yellow, produced by all speciesQ of pseudomonasPathogenecity and resistance:MC and most serious cause of infection in burnsQMC infection outside hospital is suppurative OtitisQCausative agent of Sanghai feverQBlue pus with characteristic fruity odourQPathognomic skin lesion termed ecthyma gangrenosumQ which occur singly or in small number on the perineum, buttocks and extremitiesResistant to common antiseptics and disinfectant such as dettol. Even may grow profusely in bottle of these antisepticsQExtracellular virulence factors exhibits Quorum SensingQ (cell to cell signaling system)Treatment of Pseudomonas InfectionFirst choiceSecond choice* Antipseudomonal penicillin + aminoglycoside* Antipseudomonal penicillin + quinolone* Antipseudomonal cephalosporin* Imipenam or meropenem* Aztreonam +- aminoglycoside
It formed a biofilm on bronchial walls
It underwent a mutation
It is resistant to most of antibiotics
There is a mistake with the culture technique
Pseudomonas