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Biofilm formation by nontypeable Haemophilus influenzae: strain variability, outer membrane antigen expression and role of pili.

Murphy TF, Kirkham C - BMC Microbiol. (2002)

Bottom Line: A pilus-deficient variant showed a marked impairment in biofilm formation compared to its isogenic parent.Expression of lipooligosaccharide is altered during growth as a biofilm compared to planktonic growth.Pili are important in biofilm formation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, University at Buffalo, State University of New York, USA. murphyt@acsu.buffalo.edu

ABSTRACT

Background: Nontypeable Haemophilus influenzae is an important cause of otitis media in children and lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). Several lines of evidence suggest that the bacterium grows as a biofilm in the human respiratory tract.

Results: Fifteen clinical isolates from middle ear fluid of children with otitis media and 15 isolates from sputum of adults with COPD were studied in an in vitro assay of biofilm formation. Striking variability among isolates was observed in their ability to form biofilms. Analysis of cell envelopes revealed minimal differences in banding patterns in polyacrylamide gels, alteration of expression of an epitope on lipooligosaccharide, and preservation of expression of selected epitopes on outer membrane proteins P2, P5 and P6 in biofilms compared to planktonically grown cells. A pilus-deficient variant showed a marked impairment in biofilm formation compared to its isogenic parent.

Conclusions: Nontypeable H. influenzae forms biofilms in vitro. Clinical isolates show substantial variability in their ability to grow as biofilms. Three major outer membrane proteins (P2, P5 and P6) are expressed during growth as a biofilm. Expression of lipooligosaccharide is altered during growth as a biofilm compared to planktonic growth. Pili are important in biofilm formation. As the role of biofilms in human infection becomes better defined, characterization of biofilms may be important in understanding the pathogenesis of infection and immune response to nontypeable H. influenzae in children with otitis media and adults with COPD.

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Biofilm formation by clinical isolates of nontypeable H. influenzae. Bars represent the means of three independent experiments performed in quadruplicate. Error bars represent standard deviation. Y axis is optical density at 570 nm. la: middle ear isolates: a. 83; b. 955; c. 1128; d. 1749; e. 1826; f. 2536; g. 2846; h. C4556; i. 8131; j. 8183; k. 8981; 1. 9289; m. C1425; n. DL200; o. 4505. 1b: sputum isolates: a. 5P10H1; b. 5P11H1; c. 5P30H; d. 6P5H; e. 6P8H1; f. 13P26H1; g. 14P13H5; h. 31P13H1; i. 56P40Hl; j. 74P10H1; k. 7P49H1; l. 6P32H1; m. 12P37H1; n. 13P33H1; o.18P16H1.
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Figure 1: Biofilm formation by clinical isolates of nontypeable H. influenzae. Bars represent the means of three independent experiments performed in quadruplicate. Error bars represent standard deviation. Y axis is optical density at 570 nm. la: middle ear isolates: a. 83; b. 955; c. 1128; d. 1749; e. 1826; f. 2536; g. 2846; h. C4556; i. 8131; j. 8183; k. 8981; 1. 9289; m. C1425; n. DL200; o. 4505. 1b: sputum isolates: a. 5P10H1; b. 5P11H1; c. 5P30H; d. 6P5H; e. 6P8H1; f. 13P26H1; g. 14P13H5; h. 31P13H1; i. 56P40Hl; j. 74P10H1; k. 7P49H1; l. 6P32H1; m. 12P37H1; n. 13P33H1; o.18P16H1.

Mentions: Fifteen isolates recovered from the sputum of adults with COPD and 15 isolates recovered from the middle ear fluid of children with otitis media were studied for biofilm formation. Figure 1a and 1b show that striking differences were observed among strains with regard to the ability to form biofilms. Values depicted in the bar graphs represent the mean of three independent experiments performed in quadriplicate. The error bars represent the standard deviation. Although some variability in values was seen, the level of biofilm formation was highly consistent from experiment to experiment. Strains which formed good biofilms (e.g., strains 5P11H1, 6P8H1, 13P26H1, 31P13H1, 56P40H1 and 74P10H1 from Figure 1b) and strains which formed poor biofims (e.g., 5P10H1, 6P5H, 7P49H1, 6P32H1 and 13P33H1) do so consistently. Inspection of Figure 1 reveals that one cannot readily divide strains into those which form biofilms and those which do not. Rather, a broad range of ability to form biofilms was seen among these randomly chosen 30 clinical isolates.


Biofilm formation by nontypeable Haemophilus influenzae: strain variability, outer membrane antigen expression and role of pili.

Murphy TF, Kirkham C - BMC Microbiol. (2002)

Biofilm formation by clinical isolates of nontypeable H. influenzae. Bars represent the means of three independent experiments performed in quadruplicate. Error bars represent standard deviation. Y axis is optical density at 570 nm. la: middle ear isolates: a. 83; b. 955; c. 1128; d. 1749; e. 1826; f. 2536; g. 2846; h. C4556; i. 8131; j. 8183; k. 8981; 1. 9289; m. C1425; n. DL200; o. 4505. 1b: sputum isolates: a. 5P10H1; b. 5P11H1; c. 5P30H; d. 6P5H; e. 6P8H1; f. 13P26H1; g. 14P13H5; h. 31P13H1; i. 56P40Hl; j. 74P10H1; k. 7P49H1; l. 6P32H1; m. 12P37H1; n. 13P33H1; o.18P16H1.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC113772&req=5

Figure 1: Biofilm formation by clinical isolates of nontypeable H. influenzae. Bars represent the means of three independent experiments performed in quadruplicate. Error bars represent standard deviation. Y axis is optical density at 570 nm. la: middle ear isolates: a. 83; b. 955; c. 1128; d. 1749; e. 1826; f. 2536; g. 2846; h. C4556; i. 8131; j. 8183; k. 8981; 1. 9289; m. C1425; n. DL200; o. 4505. 1b: sputum isolates: a. 5P10H1; b. 5P11H1; c. 5P30H; d. 6P5H; e. 6P8H1; f. 13P26H1; g. 14P13H5; h. 31P13H1; i. 56P40Hl; j. 74P10H1; k. 7P49H1; l. 6P32H1; m. 12P37H1; n. 13P33H1; o.18P16H1.
Mentions: Fifteen isolates recovered from the sputum of adults with COPD and 15 isolates recovered from the middle ear fluid of children with otitis media were studied for biofilm formation. Figure 1a and 1b show that striking differences were observed among strains with regard to the ability to form biofilms. Values depicted in the bar graphs represent the mean of three independent experiments performed in quadriplicate. The error bars represent the standard deviation. Although some variability in values was seen, the level of biofilm formation was highly consistent from experiment to experiment. Strains which formed good biofilms (e.g., strains 5P11H1, 6P8H1, 13P26H1, 31P13H1, 56P40H1 and 74P10H1 from Figure 1b) and strains which formed poor biofims (e.g., 5P10H1, 6P5H, 7P49H1, 6P32H1 and 13P33H1) do so consistently. Inspection of Figure 1 reveals that one cannot readily divide strains into those which form biofilms and those which do not. Rather, a broad range of ability to form biofilms was seen among these randomly chosen 30 clinical isolates.

Bottom Line: A pilus-deficient variant showed a marked impairment in biofilm formation compared to its isogenic parent.Expression of lipooligosaccharide is altered during growth as a biofilm compared to planktonic growth.Pili are important in biofilm formation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, University at Buffalo, State University of New York, USA. murphyt@acsu.buffalo.edu

ABSTRACT

Background: Nontypeable Haemophilus influenzae is an important cause of otitis media in children and lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). Several lines of evidence suggest that the bacterium grows as a biofilm in the human respiratory tract.

Results: Fifteen clinical isolates from middle ear fluid of children with otitis media and 15 isolates from sputum of adults with COPD were studied in an in vitro assay of biofilm formation. Striking variability among isolates was observed in their ability to form biofilms. Analysis of cell envelopes revealed minimal differences in banding patterns in polyacrylamide gels, alteration of expression of an epitope on lipooligosaccharide, and preservation of expression of selected epitopes on outer membrane proteins P2, P5 and P6 in biofilms compared to planktonically grown cells. A pilus-deficient variant showed a marked impairment in biofilm formation compared to its isogenic parent.

Conclusions: Nontypeable H. influenzae forms biofilms in vitro. Clinical isolates show substantial variability in their ability to grow as biofilms. Three major outer membrane proteins (P2, P5 and P6) are expressed during growth as a biofilm. Expression of lipooligosaccharide is altered during growth as a biofilm compared to planktonic growth. Pili are important in biofilm formation. As the role of biofilms in human infection becomes better defined, characterization of biofilms may be important in understanding the pathogenesis of infection and immune response to nontypeable H. influenzae in children with otitis media and adults with COPD.

Show MeSH
Related in: MedlinePlus