Previous Article | Next Article 
Antimicrobial Agents and Chemotherapy, April 1998, p. 974-977, Vol. 42, No. 4
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Alginate Lyase Promotes Diffusion of
Aminoglycosides through the Extracellular Polysaccharide of Mucoid
Pseudomonas aeruginosa
Richard A.
Hatch and
Neal L.
Schiller*
Division of Biomedical Sciences, University
of California, Riverside, California 92521
Received 6 October 1997/Returned for modification 19 December
1997/Accepted 6 February 1998
 |
ABSTRACT |
We demonstrated that a 2% suspension of Pseudomonas
aeruginosa alginate completely blocked the diffusion of
gentamicin and tobramycin, but not that of carbenicillin, illustrating
how alginate production can help protect P. aeruginosa
growing within alginate microcolonies in patients with cystic fibrosis
(CF) from the effects of aminoglycosides. This aminoglycoside diffusion
barrier was degraded with a semipurified preparation of P. aeruginosa alginate lyase, suggesting that this enzyme deserves
consideration as an adjunctive agent for CF patients colonized by
mucoid strains of P. aeruginosa.
| |
TEXT |
Pseudomonas aeruginosa is
one of the most important opportunistic human pathogens (7).
This bacterium is ubiquitous and exhibits innate resistance to a wide
range of antimicrobial agents, making infections both common and
difficult to treat. Patients with cystic fibrosis (CF) have a
multisystem disease due to a biochemical defect in the regulation of
epithelial chloride transport (35) which leads to the
accumulation of thick mucus in the lungs, causing respiratory
congestion and increased susceptibility to bronchopulmonary disease
(14, 42). Despite an aggressive host immune response
(40), patients with CF usually have chronic pulmonary
infections with P. aeruginosa which remain intractable to
antibiotic treatment (17, 30, 38), making P. aeruginosa the predominant cause of death in CF patients
(41). There is also an increasing awareness of the important
role of P. aeruginosa biofilms in the contamination of
medical biomaterials, such as catheters and prostheses (6).
The persistence of P. aeruginosa in CF patient lungs and the
establishment of bacterial biofilms, as well as the bacterial
resistance to antibiotic action and host-mediated clearance mechanisms
in these microniches, has been attributed to the production of an
exopolysaccharide called alginate (6, 17, 22, 29).
Role of alginate.
Alginate produced by mucoid strains of
P. aeruginosa is a polyuronic acid exopolysaccharide
composed of a linear polymer of 
1-4 linked D-mannuronic
and L-guluronic acids with O-acetyl side groups
found on C-2 and C-3 of the mannuronic acid residues (the percentage of
acetylation varies from strain to strain) (13). Alginate
production has been shown to inhibit nonopsonic phagocytosis by
monocytes and neutrophils both in vitro (3, 11) and in vivo
(2). Alginate also increases bacterial adherence to the respiratory epithelia (8, 31), thereby increasing the rate of colonization within the respiratory tract.
Studies examining the susceptibility and resistance of mucoid P. aeruginosa to antibiotics have yielded conflicting results. Thomassen et al. (37) compared the antibiotic
susceptibilities of mucoid and nonmucoid pairs of strains and found
that many parental mucoid strains were more sensitive to antibiotics
than their nonmucoid revertants. In contrast, Govan and Fyfe
(18) reported that mucoid strains were more resistant to
antibiotics than their nonmucoid counterparts and suggested that the
emergence of the mucoid form of P. aeruginosa in CF patient
lungs could be due in part to this increased antibiotic resistance
(18). The role of alginate as a barrier to antibiotic
penetration is supported by the studies of Bayer et al. (3),
who found that alginate production decreases the uptake and early
bactericidal effect of aminoglycosides, and by Kumon et al.
(20), who reported that alginate blocks the diffusion of
positively charged hydrophilic drugs. In contrast, Nichols et al.
(25, 26) reported that alginate had only a small role in
reducing drug penetration.
Sandwich cup assay.
We decided to directly examine the ability
of P. aeruginosa alginate to prevent the diffusion of
various antibiotics, using an adaptation of the sandwich cup assay
(20). Alginate was isolated from culture supernatants of
P. aeruginosa mucoid strains FRD1 and 144M, both originally
obtained from the sputum of patients with CF (27, 33) by the
protocol described by Franklin and Ohman (12). A log phase
culture of P. aeruginosa FRD2 (a spontaneous nonmucoid
derivative of FRD1 [28]) grown in nutrient broth
(Becton Dickinson & Co., Cockeysville, Md.) at 37°C, adjusted to an
optical density at 600 nm of 0.6, was used as the indicator strain.
After a culture plate insert with a 0.4-µm-pore-size filter (12 mm in diameter; Millipore Corporation, Bedford, Mass.) was centered in a
100-mm-diameter petri dish, 15 ml of Antibiotic Medium 11 (Difco
Laboratories, Detroit, Mich.) at 47°C was mixed with 50 µl of the
bacterial suspension and poured into the dish. After the agar had
hardened, 200 µl of either heat-solubilized 1% Noble agar (Difco) or
purified 144M or FRD1 alginate preparation (at various concentrations)
was placed into the insert and allowed to solidify. Finally, 50 µl of
various concentrations of either gentamicin, tobramycin, polymyxin B,
or carbenicillin (all from Sigma Chemical Co., St. Louis, Mo.) diluted
in one-fourth strength Dulbecco's phosphate-buffered saline (Sigma),
pH 8.0, or 50 µl of an antibiotic-alginate lyase mixture was added to
the insert. Plates were then incubated overnight at 37°C.
Preliminary experiments determined the optimal levels of antibiotics
for use in this sandwich cup assay. Zone sizes representing
inhibition
of bacterial growth were measured, and the radius (after
the
contribution of the insert was subtracted) of the zone that
was found
with Noble agar was defined as representing 100% penetration
of
antibiotics. The growth inhibition zone size for each antibiotic
against strain FRD2 increased linearly as a function of antibiotic
concentration (data not shown). Based on these results, we selected
antibiotic concentrations which gave consistent growth inhibition
radius zone sizes of ~5.50 mm for all subsequent experiments:
tobramycin (100 µg), gentamicin (200 µg), carbenicillin (200 µg),
and polymyxin B (800 µg).
Effect of alginate on antibiotic penetration.
We next examined
whether alginate can affect the growth inhibitory activity of these
antibiotics for strain FRD2. Varying amounts of purified alginate were
substituted for Noble agar in the insert cup, and antibiotics were
placed on top of the alginate prior to incubation. The antibiotic zone
sizes were measured for each alginate concentration and compared to
those obtained with 1% Noble agar as a control. Inhibition of
antibiotic activity for each alginate concentration was determined as
follows: percentage of inhibition = 100 × [1 
(radius with alginate/radius with Noble agar)], and the results are
shown in Fig. 1. When used at
concentrations below 2%, the alginate prepared from strain 144M
demonstrated greater inhibitory activity for tobramycin and for
gentamicin than the alginate from FRD1. (We also noted that at lower
concentrations, 144M alginate is more viscous than FRD1 alginate.)
However, when used at concentrations of 
2%, both alginates
completely blocked the inhibitory activity of both aminoglycosides.
Similar results were obtained with 2% alginate and polymyxin B (data
not shown). In contrast, neither 2% alginate from strain FRD1 nor 2%
alginate from strain 144M blocked the penetration of carbenicillin
(data not shown).
View larger version (15K):
[in this window]
[in a new window]
|
FIG. 1.
Effect of alginate on the antibiotic activity of
aminoglycosides. The abilities of 200 µg of gentamicin and 100 µg
of tobramycin to inhibit the growth of P. aeruginosa FRD2
were examined with either 1% Noble agar (control) or various
concentrations of purified P. aeruginosa alginate in the
insert cup. Zone sizes determined with 1% Noble agar were considered
to be 100% activity, and test zone sizes were compared to these
control values. Percentage of inhibition was calculated as follows:
100 × [1 (radius measured with alginate in the sandwich
cup assay/radius with 1% noble agar in the sandwich cup assay)]. Data
represent the means ± standard errors of the means based on at
least four experiments.
|
|
Alginate lyase.
Alginates can be enzymatically depolymerized
by lyases (eliminases) which catalyze the cleavage of the glycosidic
linkages by -elimination (32). Alginate lyases are
produced by a wide variety of bacteria, including Bacillus
circulans (19), Klebsiella pneumoniae
(5), various Pseudomonas spp. (36,
39), and P. aeruginosa (4, 9, 21, 24, 34).
In previous studies, we have demonstrated that the alginate lyase
produced by mucoid strains of P. aeruginosa can degrade
alginate (10, 34). To determine whether alginate lyase can
influence antibiotic diffusion through alginate, we first obtained a
semipurified alginate lyase preparation. We constructed pSM13 by
inserting PCR-amplified algL (which encodes the P. aeruginosa FRD1 alginate lyase [34]) into the
expression vector pET21c (Novagen, Inc., Madison, Wis.).
Escherichia coli BL21(DE3)(pSM13) was then grown in Luria
broth-Lennox (Difco) with 100 µg of ampicillin per ml at 25°C
overnight, induced with 1 mM
isopropyl--D-thiogalactopyranoside (IPTG), and incubated for an additional 6 h at 25°C before being harvested. AlgL was extracted from the bacterial pellets by the heat shock procedure described previously (34). After concentration by
ultrafiltration, NaCl was added at a final concentration of 500 mM and
the preparation was fractionated on a Sephacryl HR300 column (Pharmacia
Biotech, Upsala, Sweden) equilibrated with 25 mM
K2HPO4-500 mM NaCl (pH 7.0) at 4°C. Column
fractions were examined for alginate lyase activity by the
thiobarbituric acid assay (34). Enzyme-containing fractions
were pooled and dialyzed overnight with 25 mM
K2HPO4 (pH 7.0) at 4°C, loaded onto a
Sepharose HP ion-exchange column (Pharmacia Biotech), and eluted with a
continuous NaCl gradient from 0 to 500 mM in 25 mM
K2HPO4 (pH 7.0) at 4°C. Enzymatically active
fractions were pooled, concentrated by ultrafiltration, dialyzed
against 25 mM K2HPO4 (pH 7.0) at 4°C, and
stored at 20°C. Enzyme activity was expressed in enzyme units (EU),
where one EU represents the amount of enzyme that produces 1 nmol of
-formyl-pyruvate per min per ml at 37°C (10). Samples
were examined by electrophoresis with a 0.75-mm-thick Laemmli 14%
sodium dodecyl sulfate-polyacrylamide gel which was silver stained
(Fig. 2).
View larger version (119K):
[in this window]
[in a new window]
|
FIG. 2.
Silver-stained sodium dodecyl sulfate-polyacrylamide gel
electrophoresis profile of semipurified alginate lyase. Lane 1, molecular weight standards (in thousands); lane 2, crude enzyme
preparation; lane 3, enzyme preparation after fractionation on a
Sephacryl H300 column; lane 4, enzyme preparation after fractionation
on a Sepharose HP ion-exchange column.
|
|
Effect of alginate lyase on aminoglycoside diffusion through
alginate.
Varying amounts of this alginate lyase preparation were
mixed with the indicated aminoglycoside (in a final volume of 50 µl) and layered on top of either 2% FRD1 alginate or 2% 144M alginate in
the insert cup. The ability of this enzyme to influence aminoglycoside penetration through the alginate preparations was determined by measuring the growth inhibitory zones produced by the aminoglycosides in the presence or absence of the enzyme. The results obtained with
FRD1 alginate are shown in Fig. 3.
Increasing amounts of alginate lyase decreased the inhibitory activity
of 2% FRD1 alginate for both aminoglycosides. When 10.32 EU of
alginate lyase was used, the activity of gentamicin for FRD1 was
~79% of that seen in the absence of alginate, whereas that of
tobramycin was ~92%. Although a greater number of alginate lyase EU
was required to affect aminoglycoside penetration through 144M
alginate, 100 AlgL EU restored ~56% of the growth inhibitory
activity of gentamicin for strain FRD2 and ~84% of the growth
inhibitory activity of tobramycin (Fig.
4). These results demonstrate that this
enzyme can degrade both alginate preparations and allows these
aminoglycosides to penetrate to the P. aeruginosa FRD2
target organisms.
View larger version (35K):
[in this window]
[in a new window]
|
FIG. 3.
Effect of AlgL on alginate inhibition of aminoglycoside
activity. The abilities of 200 µg of gentamicin and 100 µg of
tobramycin to inhibit the growth of P. aeruginosa FRD2 were
examined with either 1% Noble agar (control) or 2% FRD1 alginate with
various concentrations of AlgL in the insert cup. Zone sizes measured
with 1% noble agar were considered to represent 100% antibiotic
activity, and zone sizes obtained with 2% FRD1 alginate plus AlgL were
compared to these control values. Data represent the means ± standard errors of the means based on at least three experiments.
|
|
View larger version (24K):
[in this window]
[in a new window]
|
FIG. 4.
Effect of AlgL on alginate inhibition of aminoglycoside
penetration. The abilities of 200 µg of gentamicin and 100 µg of
tobramycin to inhibit the growth of P. aeruginosa FRD2 were
examined with either 1% Noble agar (control) or 2% 144 M alginate
with various concentrations of AlgL in the insert cup. Zone sizes
measured with 1% Noble agar were considered to represent 100%
antibiotic activity, and zone sizes obtained with 2% 144 M alginate
plus AlgL were compared to these control values. Data represent the
means ± standard errors of the means based on at least three
experiments.
|
|
Discussion.
Our results demonstrate that when used at a final
concentration of 2%, alginates prepared from two clinical P. aeruginosa isolates can completely block the ability of gentamicin
(at 200 µg), tobramycin (at 100 µg), and polymyxin B (at 800 µg)
to inhibit the growth of P. aeruginosa. In contrast,
carbenicillin was not inhibited by this concentration of alginate.
These results can be interpreted as indicating that the polyanionic
alginate acts as an ionic trapping agent for the positively charged
aminoglycosides and polymyxin B, a model proposed previously by other
investigators (1, 15, 25) and supported by our data.
Gordon et al. (
16) found that slime dispersants (such as
EDTA or NaCl) can reduce alginate viscosity and facilitate diffusion
of
the antipseudomonal antibiotics through alginate. In the present
study,
we demonstrated that alginate lyase, an enzyme purified
from
P. aeruginosa FRD1, can facilitate diffusion of aminoglycosides
to
the target bacteria. Although the 144M alginate was somewhat
more
resistant to the effects of this enzyme than the FRD1 alginate
(possibly due to variation in mannuronic-to-guluronic acid ratios
or
differences in the percentage of acetylation), both alginate
preparations were effectively degraded by this enzyme. This result
suggests that the blocking activity of the alginate may be due
to its
ability to form viscous gels as well as to its ionic charge
and that
when the alginate is degraded, this aminoglycoside-blocking
activity is
effectively reduced.
We and other investigators have suggested that alginate lyase treatment
of alginate-encoated bacteria can render them more
sensitive to
antibiotics or host defenses (
2,
11,
23).
The present study
addresses this issue with a simple, direct assay,
the results of which
support the hypothesis that degradation of
alginate within the lungs of
CF patients may render the infecting
pathogens more susceptible to
aminoglycoside chemotherapy.
| |
ACKNOWLEDGMENTS |
This work was supported in part by grant AI36325 from the National
Institutes of Health.
| |
FOOTNOTES |
*
Corresponding author. Mailing address: Division of
Biomedical Sciences, University of California, Riverside, CA 92521. Phone: (909) 787-4569. Fax: (909) 787-5504. E-mail:
neal.schiller{at}ucr.edu.
| |
REFERENCES |
| 1.
|
Allison, D. G., and M. J. Matthews.
1992.
Effect of polysaccharide interactions on antibiotic susceptibility of Pseudomonas aeruginosa.
J. Appl. Bacteriol.
73:484-488[Medline].
|
| 2.
|
Bayer, A. S.,
S. Park,
M. C. Ramos,
C. C. Nast,
F. Eftekhar, and N. L. Schiller.
1992.
Effects of alginase on the natural history and antibiotic therapy of experimental endocarditis caused by mucoid Pseudomonas aeruginosa.
Infect. Immun.
60:3979-3985[Abstract/Free Full Text].
|
| 3.
|
Bayer, A. S.,
D. P. Speert,
S. Park,
J. Tu,
M. Witt,
C. C. Nast, and D. C. Norman.
1991.
Functional role of mucoid exopolysaccharide (alginate) in antibiotic-induced and polymorphonuclear leukocyte-mediated killing of Pseudomonas aeruginosa.
Infect. Immun.
59:302-308[Abstract/Free Full Text].
|
| 4.
|
Boyd, A.,
M. Ghosh,
T. B. May,
D. Shinabarger,
R. Keogh, and A. M. Chakrabarty.
1993.
Sequence of the algL gene of Pseudomonas aeruginosa and purification of its alginate lyase product.
Gene
131:1-8[Medline].
|
| 5.
|
Caswell, R. C.,
P. Gacesa,
K. E. Lutrell, and A. J. Weightman.
1989.
Molecular cloning and heterologous expression of a Klebsiella pneumoniae gene encoding alginate lyase.
Gene
75:127-134[Medline].
|
| 6.
|
Costerton, J. W.,
K.-J. Cheng,
G. G. Geesey,
T. J. Ladd,
J. C. Nickel,
M. Dasgupta, and T. J. Marrie.
1987.
Bacterial biofilms in nature and disease.
Annu. Rev. Microbiol.
41:435-464[Medline].
|
| 7.
| Cross, A., J. R. Allen, J. Burke, G. Ducel,
A. Harris, J. John, D. Johnson, M. Lew, B. MacMillan, R. Skalova, R. Wenzel, and J. Tenney. 1983. Nosocomial infections due to
Pseudomonas aeruginosa: review of recent trends. Rev.
Infect. Dis. 5(Suppl.):S837-S845.
|
| 8.
|
Doig, P.,
N. R. Smith,
T. Todd, and R. T. Irvin.
1987.
Characterization of the binding of Pseudomonas aeruginosa alginate to epithelial cells.
Infect. Immun.
55:864-873[Abstract/Free Full Text].
|
| 9.
|
Dunne, W. M., Jr., and F. L. A. Buckmire.
1985.
Partial purification and characterization of a polymannuronic acid depolymerase produced by a mucoid strain of Pseudomonas aeruginosa isolated from a patient with cystic fibrosis.
Appl. Environ. Microbiol.
50:562-567[Abstract/Free Full Text].
|
| 10.
|
Eftekhar, F., and N. L. Schiller.
1994.
Partial purification and characterization of a mannuronan-specific alginate lyase from Pseudomonas aeruginosa.
Curr. Microbiol.
29:37-42.
|
| 11.
|
Eftekhar, F., and D. P. Speert.
1988.
Alginase treatment of mucoid Pseudomonas aeruginosa enhances phagocytosis by human monocyte-derived macrophages.
Infect. Immun.
56:2788-2793[Abstract/Free Full Text].
|
| 12.
|
Franklin, M. J., and D. E. Ohman.
1993.
Identification of algF in the alginate biosynthetic gene cluster of Pseudomonas aeruginosa which is required for alginate acetylation.
J. Bacteriol.
175:5057-5065[Abstract/Free Full Text].
|
| 13.
|
Gacesa, P., and N. J. Russell.
1990.
The structure and properties of alginate, p. 29-49.
In
P. Gacesa, and N. J. Russell (ed.), Pseudomonas infection and alginates: biochemistry, genetics and pathology. Chapman and Hall, London, England.
|
| 14.
|
George, R. H.
1987.
Pseudomonas infection in cystic fibrosis.
Arch. Dis. Child.
62:438-439[Free Full Text].
|
| 15.
|
Gilbert, P., and M. R. W. Brown.
1995.
Mechanisms of the protection of bacterial biofilms from antimicrobial agents, p. 118-130.
In
H. M. Lappin-Scott, and J. W. Costerton (ed.), Microbial biofilms. Cambridge University Press, Cambridge, Great Britain.
|
| 16.
|
Gordon, C. A.,
N. A. Hodges, and C. Marriott.
1991.
Use of slime dispersants to promote antibiotic penetration through the extracellular polysaccharide of mucoid Pseudomonas aeruginosa.
Antimicrob. Agents Chemother.
35:1258-1260[Abstract/Free Full Text].
|
| 17.
|
Govan, J. R. W., and V. Deretic.
1996.
Microbial pathogenesis in cystic fibrosis: mucoid Pseudomonas aeruginosa and Burkholderia cepacia.
Microbiol. Rev.
60:539-574[Abstract/Free Full Text].
|
| 18.
|
Govan, J. R. W., and J. A. M. Fyfe.
1978.
Mucoid Pseudomonas aeruginosa and cystic fibrosis: resistance of the mucoid form to carbenicillin, flucloxacillin, and tobramycin and the isolation of mucoid variants in vitro.
J. Antimicrob. Chemother.
4:233-240[Abstract/Free Full Text].
|
| 19.
|
Hansen, J. B.,
R. S. Doubet, and J. Ram.
1984.
Alginase enzyme production by Bacillus circulans.
Appl. Environ. Microbiol.
47:704-709[Abstract/Free Full Text].
|
| 20.
|
Kumon, H.,
K. Tomachika,
T. Matunaga,
M. Ogawa, and H. Ohmori.
1994.
A sandwich cup method for the penetration assay of antimicrobial agents through Pseudomonas exopolysaccharides.
Microbiol. Immunol.
38:615-619[Medline].
|
| 21.
|
Linker, A., and L. R. Evans.
1984.
Isolation and characterization of an alginase from mucoid strains of Pseudomonas aeruginosa.
J. Bacteriol.
159:58-64.
|
| 22.
|
May, T. B.,
D. Shinabarger,
R. Maharaj,
J. Kato,
L. Chu,
J. D. DeVault,
S. Roychoudhury,
N. A. Zielinsky,
A. Berry,
R. K. Rothmel,
T. K. Misra, and A. M. Chakrabarty.
1991.
Alginate synthesis by Pseudomonas aeruginosa: a key pathogenic factor in chronic pulmonary infections of cystic fibrosis patients.
Clin. Microbiol. Rev.
4:191-196[Abstract/Free Full Text].
|
| 23.
|
Meluleni, G. J.,
M. Grout,
D. J. Evans, and G. B. Pier.
1995.
Mucoid Pseudomonas aeruginosa growing in a biofilm in vitro are killed by opsonic antibodies to the mucoid exopolysaccharide capsule but not by antibodies produced during chronic lung infection in cystic fibrosis patients.
J. Immunol.
155:2029-2038[Abstract].
|
| 24.
|
Nguyen, L. K., and N. L. Schiller.
1989.
Identification of a slime exopolysaccharide depolymerase in mucoid strains of Pseudomonas aeruginosa.
Curr. Microbiol.
18:323-329.
|
| 25.
|
Nichols, W. W.,
S. M. Dorrington,
M. P. E. Slack, and H. L. Walmsley.
1988.
Inhibition of tobramycin diffusion by binding to alginate.
Antimicrob. Agents Chemother.
32:518-523[Abstract/Free Full Text].
|
| 26.
|
Nichols, W. W.,
M. J. Evans,
M. P. E. Slack, and H. L. Walmsley.
1989.
The penetration of antibiotics into aggregates of mucoid and non-mucoid Pseudomonas aeruginosa.
J. Gen. Microbiol.
135:1291-1303[Abstract/Free Full Text].
|
| 27.
|
Ohman, D. E., and A. M. Chakrabarty.
1981.
Genetic mapping of chromosomal determinants for the production of the exopolysaccharide alginate in a Pseudomonas aeruginosa cystic fibrosis isolate.
Infect. Immun.
33:142-148[Abstract/Free Full Text].
|
| 28.
|
Ohman, D. E., and A. M. Chakrabarty.
1982.
Utilization of human respiratory secretions by mucoid Pseudomonas aeruginosa of cystic fibrosis origin.
Infect. Immun.
37:662-669[Abstract/Free Full Text].
|
| 29.
| Pedersen, S. S. 1992. Lung infection with
alginate-producing, mucoid Pseudomonas aeruginosa in cystic
fibrosis. APMIS 100(Suppl. 28):1-79.
|
| 30.
|
Pier, G. B.
1985.
Pulmonary disease associated with Pseudomonas aeruginosa in cystic fibrosis: current status of the host-bacterium interaction.
J. Infect. Dis.
151:575-580[Medline].
|
| 31.
|
Ramphal, R.,
C. Guay, and G. B. Pier.
1987.
Pseudomonas aeruginosa adhesins for tracheobronchial mucin.
Infect. Immun.
55:600-603[Abstract/Free Full Text].
|
| 32.
|
Romeo, T., and J. F. Preston, III.
1986.
Depolymerization of alginate by an extracellular alginate lyase from a marine bacterium: substrate specificity and accumulation of reaction products.
Biochemistry
25:8391-8396.
|
| 33.
|
Schiller, N. L., and R. A. Hatch.
1983.
The serum sensitivity, colonial morphology, serogroup specificity, and outer membrane protein of Pseudomonas aeruginosa strains isolated from several clinical sites.
Diagn. Microbiol. Infect. Dis.
1:143-157.
|
| 34.
|
Schiller, N. L.,
S. R. Monday,
C. M. Boyd,
N. T. Keen, and D. E. Ohman.
1993.
Characterization of the Pseudomonas aeruginosa alginate lyase gene (algL): cloning, sequencing and expression in Escherichia coli.
J. Bacteriol.
175:4780-4789[Abstract/Free Full Text].
|
| 35.
|
Sferra, T. J., and F. S. Collins.
1993.
The molecular biology of cystic fibrosis.
Annu. Rev. Med.
44:133-144[Medline].
|
| 36.
|
Sutherland, I. W., and G. A. Keen.
1981.
Alginases from Beneckea pelagia and Pseudomonas species.
J. Appl. Biochem.
3:48-57.
|
| 37.
|
Thomassen, M. J.,
C. A. Demko,
B. Boxerbaum,
R. C. Stern, and P. J. Kuchenbrod.
1979.
Multiple isolates of Pseudomonas aeruginosa with differing antimicrobial susceptibility patterns from patients with cystic fibrosis.
J. Infect. Dis.
140:873-880[Medline].
|
| 38.
|
Thomassen, M. J.,
C. A. Demko, and C. F. Doershuk.
1987.
Cystic fibrosis: a review of pulmonary infections and interventions.
Pediatr. Pulmonol.
3:334-351[Medline].
|
| 39.
|
Von Riesen, L. V.
1980.
Digestion of algin by Pseudomonas maltophilia and Pseudomonas putida.
Appl. Environ. Microbiol.
39:92-96[Abstract/Free Full Text].
|
| 40.
|
Warner, J. O.
1992.
Immunology of cystic fibrosis.
Br. Med. Bull.
48:893-911[Abstract/Free Full Text].
|
| 41.
|
Welsh, M. J.,
L.-C. Tsui,
T. F. Boat, and A. L. Beaudet.
1995.
Cystic fibrosis, p. 3799-3876.
In
C. R. Scriver, A. L. Beaudet, W. S. Sly, and D. Valle (ed.), The metabolic basis of inherited disease. McGraw-Hill, Inc., New York, N.Y.
|
| 42.
|
Wood, R. E.,
T. F. Boat, and C. F. Doershuk.
1976.
Cystic fibrosis: state of the art.
Am. Rev. Respir. Dis.
113:833-878[Medline].
|
Antimicrobial Agents and Chemotherapy, April 1998, p. 974-977, Vol. 42, No. 4
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Hagins, J. M., Locy, R., Silo-Suh, L.
(2009). Isocitrate Lyase Supplies Precursors for Hydrogen Cyanide Production in a Cystic Fibrosis Isolate of Pseudomonas aeruginosa. J. Bacteriol.
191: 6335-6339
[Abstract]
[Full Text]
-
Alipour, M., Suntres, Z. E., Omri, A.
(2009). Importance of DNase and alginate lyase for enhancing free and liposome encapsulated aminoglycoside activity against Pseudomonas aeruginosa. J Antimicrob Chemother
64: 317-325
[Abstract]
[Full Text]
-
Mulet, X., Macia, M. D., Mena, A., Juan, C., Perez, J. L., Oliver, A.
(2009). Azithromycin in Pseudomonas aeruginosa Biofilms: Bactericidal Activity and Selection of nfxB Mutants. Antimicrob. Agents Chemother.
53: 1552-1560
[Abstract]
[Full Text]
-
Lindsey, T. L., Hagins, J. M., Sokol, P. A., Silo-Suh, L. A.
(2008). Virulence determinants from a cystic fibrosis isolate of Pseudomonas aeruginosa include isocitrate lyase. Microbiology
154: 1616-1627
[Abstract]
[Full Text]
-
Fong, J. C. N., Yildiz, F. H.
(2007). The rbmBCDEF Gene Cluster Modulates Development of Rugose Colony Morphology and Biofilm Formation in Vibrio cholerae. J. Bacteriol.
189: 2319-2330
[Abstract]
[Full Text]
-
Silo-Suh, L., Suh, S.-J., Phibbs, P. V., Ohman, D. E.
(2005). Adaptations of Pseudomonas aeruginosa to the Cystic Fibrosis Lung Environment Can Include Deregulation of zwf, Encoding Glucose-6-Phosphate Dehydrogenase. J. Bacteriol.
187: 7561-7568
[Abstract]
[Full Text]
-
Robles-Price, A., Wong, T. Y., Sletta, H., Valla, S., Schiller, N. L.
(2004). AlgX Is a Periplasmic Protein Required for Alginate Biosynthesis in Pseudomonas aeruginosa. J. Bacteriol.
186: 7369-7377
[Abstract]
[Full Text]
-
Al-Fattani, M. A., Douglas, L. J.
(2004). Penetration of Candida Biofilms by Antifungal Agents. Antimicrob. Agents Chemother.
48: 3291-3297
[Abstract]
[Full Text]
-
Magnet, S., Smith, T.-A., Zheng, R., Nordmann, P., Blanchard, J. S.
(2003). Aminoglycoside Resistance Resulting from Tight Drug Binding to an Altered Aminoglycoside Acetyltransferase. Antimicrob. Agents Chemother.
47: 1577-1583
[Abstract]
[Full Text]
-
Walters, M. C. III, Roe, F., Bugnicourt, A., Franklin, M. J., Stewart, P. S.
(2003). Contributions of Antibiotic Penetration, Oxygen Limitation, and Low Metabolic Activity to Tolerance of Pseudomonas aeruginosa Biofilms to Ciprofloxacin and Tobramycin. Antimicrob. Agents Chemother.
47: 317-323
[Abstract]
[Full Text]
-
Donlan, R. M., Costerton, J. W.
(2002). Biofilms: Survival Mechanisms of Clinically Relevant Microorganisms. Clin. Microbiol. Rev.
15: 167-193
[Abstract]
[Full Text]
-
Hoiby, N.
(2002). New antimicrobials in the management of cystic fibrosis. J Antimicrob Chemother
49: 235-238
[Full Text]
-
Da Costa, A., Michaud, P., Petit, E., Heyraud, A., Colin-Morel, P., Courtois, B., Courtois, J.
(2001). Purification and Properties of a Glucuronan Lyase from Sinorhizobium meliloti M5N1CS (NCIMB 40472). Appl. Environ. Microbiol.
67: 5197-5203
[Abstract]
[Full Text]
-
Preston, L. A., Wong, T. Y., Bender, C. L., Schiller, N. L.
(2000). Characterization of Alginate Lyase from Pseudomonas syringae pv. syringae. J. Bacteriol.
182: 6268-6271
[Abstract]
[Full Text]
-
Peciña, A., Pascual, A., Paneque, A.
(1999). Cloning and Expression of the algL Gene, Encoding the Azotobacter chroococcum Alginate Lyase: Purification and Characterization of the Enzyme. J. Bacteriol.
181: 1409-1414
[Abstract]
[Full Text]
Top
Abstract
Text
