Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Type of study
Language
Publication year range
1.
Photochem Photobiol ; 96(3): 611-617, 2020 05.
Article in English | MEDLINE | ID: mdl-32105346

ABSTRACT

Moraxella catarrhalis is one of the major otopathogens of otitis media (OM) in childhood. M. catarrhalis tends to form biofilm, which contributes to the chronicity and recurrence of infections, as well as resistance to antibiotic treatment. In this study, we aimed to investigate the effectiveness of antimicrobial blue light (aBL; 405 nm), an innovative nonpharmacological approach, for the inactivation of M. catarrhalis OM. M. catarrhalis either in planktonic suspensions or 24-h old biofilms were exposed to aBL at the irradiance of 60 mW cm-2 . Under an aBL exposure of 216 J cm-2 , a >4-log10 colony-forming units (CFU) reduction in planktonic suspensions and a >3-log10 CFU reduction in biofilms were observed. Both transmission electron microscopy and scanning electron microscopy revealed aBL-induced morphological damage in M. catarrhalis. Ultraperformance liquid chromatography results indicated that protoporphyrin IX and coproporphyrin were the two most abundant species of endogenous photosensitizing porphyrins. No statistically significant reduction in the viability of HaCaT cells was observed after an aBL exposure of up to 216 J cm-2 . Collectively, our results suggest that aBL is potentially an effective and safe alternative therapy for OM caused by M. catarrhalis. Further in vivo studies are warranted before this optical approach can be moved to the clinics.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Light , Moraxella catarrhalis/radiation effects , Otitis Media/drug therapy , Photosensitizing Agents/therapeutic use , Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Cell Line , Humans , Moraxella catarrhalis/drug effects , Otitis Media/microbiology , Photosensitizing Agents/pharmacology
2.
J Microbiol Methods ; 114: 38-9, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25937246

ABSTRACT

We evaluated survival in WHO-recommended STGG storage medium of bacteria causing respiratory-tract infection. Streptococcus pneumoniae and Moraxella catarrhalis survived as single and mixed isolates stored at -70°C for 12.5 years, but Haemophilus influenzae less than 4 years. All the bacteria survived in the nasopharyngeal specimens at -70°C for 11 years.


Subject(s)
Freezing , Haemophilus influenzae/physiology , Microbial Viability/radiation effects , Moraxella catarrhalis/physiology , Nasopharynx/microbiology , Specimen Handling , Streptococcus pneumoniae/physiology , Bacteriological Techniques , Culture Media/chemistry , Haemophilus influenzae/radiation effects , Moraxella catarrhalis/radiation effects , Streptococcus pneumoniae/radiation effects , Time Factors
3.
Lasers Surg Med ; 46(9): 712-7, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25154610

ABSTRACT

BACKGROUND AND OBJECTIVE: Moraxella catarrhalis is a significant cause of pediatric otitis media (OM), which is the most prevalent bacterial infection in children and primary reason for antibiotic administration in this population. Moreover, biofilm formation has been implicated as a primary mechanism of chronic or recurrent OM disease. As bacterial biofilms are inherently resistant to most antibiotics and these complex structures also present a significant challenge to the immune system, there is a clear need to identify novel antimicrobial approaches to treat OM infections. In this study, we evaluated the potential efficacy of antibacterial photodynamic therapy (aPDT) with porfimer sodium (Photofrin (PF)) against planktonic as well as biofilm-associated M. catarrhalis. MATERIALS AND METHODS: The bactericidal activity of aPDT with PF was assessed against multiple recent clinical isolates of M. catarrhalis grown planktonically as well as in biofilms. The bactericidal activity of PF-aPDT was quantified by enumeration of colony forming units post-treatment. The effect of aPDT on M. catarrhalis biofilms was further investigated with scanning electron microscopy (SEM) imaging. RESULTS: aPDT with PF significantly reduced M. catarrhalis viability. Although PF-aPDT caused higher killing in planktonic grown organisms (5-6 log kill), biofilm grown bacteria also demonstrated a statistically significant reduction in viable organisms (3-4 log decrease in recoverable bacteria) following treatment as compared to saline only controls (P < 0.01). SEM studies indicated the PF-aPDT treated bacteria exhibited prominent morphological changes with visibly distorted cell membranes. CONCLUSIONS: aPDT with PF elicits significant bactericidal activity against both planktonic and biofilm-associated M. catarrhalis, suggesting this technology warrants further analysis as a potential novel antimicrobial treatment for acute or recurrent OM.


Subject(s)
Biofilms/drug effects , Dihematoporphyrin Ether/pharmacology , Moraxella catarrhalis/drug effects , Moraxella catarrhalis/growth & development , Photochemotherapy , Photosensitizing Agents/pharmacology , Biofilms/growth & development , Biofilms/radiation effects , Lasers, Dye , Lasers, Solid-State , Microbial Viability/drug effects , Microbial Viability/radiation effects , Moraxella catarrhalis/radiation effects
4.
BMC Microbiol ; 11: 182, 2011 Aug 12.
Article in English | MEDLINE | ID: mdl-21838871

ABSTRACT

BACKGROUND: Moraxella catarrhalis, a major nasopharyngeal pathogen of the human respiratory tract, is exposed to rapid downshifts of environmental temperature when humans breathe cold air. It was previously shown that the prevalence of pharyngeal colonization and respiratory tract infections caused by M. catarrhalis are greatest in winter. The aim of this study was to investigate how M. catarrhalis uses the physiologic exposure to cold air to upregulate pivotal survival systems in the pharynx that may contribute to M. catarrhalis virulence. RESULTS: A 26°C cold shock induces the expression of genes involved in transferrin and lactoferrin acquisition, and enhances binding of these proteins on the surface of M. catarrhalis. Exposure of M. catarrhalis to 26°C upregulates the expression of UspA2, a major outer membrane protein involved in serum resistance, leading to improved binding of vitronectin which neutralizes the lethal effect of human complement. In contrast, cold shock decreases the expression of Hemagglutinin, a major adhesin, which mediates B cell response, and reduces immunoglobulin D-binding on the surface of M. catarrhalis. CONCLUSION: Cold shock of M. catarrhalis induces the expression of genes involved in iron acquisition, serum resistance and immune evasion. Thus, cold shock at a physiologically relevant temperature of 26°C induces in M. catarrhalis a complex of adaptive mechanisms that enables the bacterium to target their host cellular receptors or soluble effectors and may contribute to enhanced growth, colonization and virulence.


Subject(s)
Blood Bactericidal Activity , Cold Temperature , Gene Expression Regulation, Bacterial , Immune Evasion , Iron/metabolism , Moraxella catarrhalis/radiation effects , Stress, Physiological , Humans , Membrane Transport Proteins/biosynthesis , Moraxella catarrhalis/pathogenicity , Moraxella catarrhalis/physiology , Virulence Factors/metabolism
SELECTION OF CITATIONS
SEARCH DETAIL
...