Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

Corkill, J. E.; Deveney, Joanne; Pratt, Julie M.; Shears, P.; Smyth, Alan; Heaf, D P

doi:10.1203/00006450-199403000-00003

Cited by 9 publications

(6 citation statements)

References 8 publications

(10 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The excellent penetration of quinolones and nitroimidazoles into intra-abdominal infected tissues may be a factor contributing to the better outcome of patients receiving this regimen. It should be emphasised that the antimicrobial activity of various agents against several pathogens is considerably affected by changes in pH [31,32], which is of particular importance in the milieu of intra-abdominal infections where a low pH is common.…”

Section: Discussionmentioning

confidence: 99%

Ciprofloxacin/metronidazole versus β-lactam-based treatment of intra-abdominal infections: a meta-analysis of comparative trials

Matthaiou¹,

Peppas²,

Bliziotis³

et al. 2006

International Journal of Antimicrobial Agents

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Ciprofloxacin/metronidazole versus β-lactam-based treatment of intra-abdominal infections: a meta-analysis of comparative trials

Matthaiou¹,

Peppas²,

Bliziotis³

et al. 2006

International Journal of Antimicrobial Agents

View full text Add to dashboard Cite

“…CF airways provide a highly variable habitat with diverse predisposing micro-environmental conditions and regional differences in microflora [ 23 , 24 , 25 ]. Whilst it is now well known that the thick dehydrated mucus that coats the CF airway has hypoxic regions, and as alveolar hypoventilation and severe hypercapnia are frequently observed in critically ill adult CF patients, it is highly likely that CO 2 levels are also variable and in excess of that occurring in the healthy lung [ 23 , 26 , 27 ]. Therefore S .…”

Section: Discussionmentioning

confidence: 99%

Environment and Colonisation Sequence Are Key Parameters Driving Cooperation and Competition between Pseudomonas aeruginosa Cystic Fibrosis Strains and Oral Commensal Streptococci

et al. 2015

View full text Add to dashboard Cite

Cystic fibrosis (CF) patient airways harbour diverse microbial consortia that, in addition to the recognized principal pathogen Pseudomonas aeruginosa, include other bacteria commonly regarded as commensals. The latter include the oral (viridans) streptococci, which recent evidence indicates play an active role during infection of this environmentally diverse niche. As the interactions between inhabitants of the CF airway can potentially alter disease progression, it is important to identify key cooperators/competitors and environmental influences if therapeutic intervention is to be improved and pulmonary decline arrested. Importantly, we recently showed that virulence of the P. aeruginosa Liverpool Epidemic Strain (LES) could be potentiated by the Anginosus-group of streptococci (AGS). In the present study we explored the relationships between other viridans streptococci (Streptococcus oralis, Streptococcus mitis, Streptococcus gordonii and Streptococcus sanguinis) and the LES and observed that co-culture outcome was dependent upon inoculation sequence and environment. All four streptococcal species were shown to potentiate LES virulence factor production in co-culture biofilms. However, in the case of S. oralis interactions were environmentally determined; in air cooperation within a high cell density co-culture biofilm occurred together with stimulation of LES virulence factor production, while in an atmosphere containing added CO2 this species became a competitor antagonising LES growth through hydrogen peroxide (H2O2) production, significantly altering biofilm population dynamics and appearance. Streptococcus mitis, S. gordonii and S. sanguinis were also capable of H2O2 mediated inhibition of P. aeruginosa growth, but this was only visible when inoculated as a primary coloniser prior to introduction of the LES. Therefore, these observations, which are made in conditions relevant to the biology of CF disease pathogenesis, show that the pathogenic and colonisation potential of P. aeruginosa isolates can be modulated positively and negatively by the presence of oral commensal streptococci.

show abstract

“…Thus, in the characteristically depleted CF periciliary liquid layer, low pH ASL would ''tighten'' adhesive interactions between mucins in the mucus layer and membrane surface tethered mucins (17), rendering cough clearance of adherent mucus less effective (30). Failure of CF epithelia to compensate for an intraluminal acid load may heighten the inflammatory response in the airway by interfering with bactericidal activity (31,32), promoting secretion by immune cells of substances harmful to the lung (33) and reducing the efficacy of commonly used antibiotics against Pseudomonas aeruginosa (34).…”

Section: Discussionmentioning

confidence: 99%

Abnormal surface liquid pH regulation by cultured cystic fibrosis bronchial epithelium

Coakley

Grubb

Paradiso

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

268

302

View full text Add to dashboard Cite

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR)-dependent airway epithelial bicarbonate transport is hypothesized to participate in airway surface liquid pH regulation and contribute to lung defense. We measured pH and ionic composition in apical surface liquid (ASL) on polarized normal (NL) and CF primary bronchial epithelial cell cultures under basal conditions, after cAMP stimulation, and after challenge with luminal acid loads. Under basal conditions, CF epithelia acidified ASL more rapidly than NL epithelia. Two ASL pH regulatory paths that contributed to basal pH were identified in the apical membrane of airway epithelia, and their activities were measured. We detected a ouabain-sensitive (nongastric) H ؉ ,K ؉ -ATPase that acidified ASL, but its activity was not different in NL and CF cultures. We also detected the following evidence for a CFTR-dependent HCO 3 ؊ secretory pathway that was defective in CF: (i) ASL [HCO 3 ؊ ] was higher in NL than CF ASL; (ii) activating CFTR with forskolin͞3-isobutyl-1-methylxanthine alkalinized NL ASL but acidified CF ASL; and (iii) NL airway epithelia more rapidly and effectively alkalinized ASL in response to a luminal acid challenge than CF epithelia. We conclude that cultured human CF bronchial epithelial pH ASL is abnormally regulated under basal conditions because of absent CFTRdependent HCO 3 ؊ secretion and that this defect can lead to an impaired capacity to respond to airway conditions associated with acidification of ASL.

show abstract

Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

Cited by 9 publications

References 8 publications

Ciprofloxacin/metronidazole versus β-lactam-based treatment of intra-abdominal infections: a meta-analysis of comparative trials

Ciprofloxacin/metronidazole versus β-lactam-based treatment of intra-abdominal infections: a meta-analysis of comparative trials

Environment and Colonisation Sequence Are Key Parameters Driving Cooperation and Competition between Pseudomonas aeruginosa Cystic Fibrosis Strains and Oral Commensal Streptococci

Abnormal surface liquid pH regulation by cultured cystic fibrosis bronchial epithelium

Contact Info

Product

Resources

About