Effects of fluoroquinolones on bacterial adhesion and on preformed biofilm of strains isolated from urinary double J stents

Analysis of Characteristics, Pathogens and Drug Resistance of Urinary Tract Infection Associated with Long-Term Indwelling Double-J Stent

Objective

To investigate the characteristics, pathogens and drug resistance of urinary tract infection (UTI) associated with long-term indwelling double-J stent.

Methods

The clinical data of 102 patients with urinary tract infection associated with long-term indwelling double-J stent in University-Town Hospital of Chongqing Medical University and Chongqing Traditional Chinese Medicine Hospital from September 2010 to July 2022 were collected retrospectively, and the difference between etiological characteristics were analyzed. Urine and double-J stent samples of patients were collected for pathogen identification and drug sensitivity test.

Results

A total of 102 patients, 39 (38.23%) males and 63 (61.77%) females, aged 24-72 years, with a median age of 48 years, were included in this study. Urinary calculi (40.20%) and ureteral stricture (24.50%) were the main causes of urinary tract infection associated with long-term indwelling double-J stent. Among the patients with urinary tract infection caused by double-J stent, female patients were higher than male patients (61.77% vs 38.23%). In terms of positive rate of pathogenic bacteria culture, the rate of double-J stent was higher than that of urine (67.65% vs 35.29%). The main pathogenic bacteria in urine were Escherichia coli (30.55%) of Gram negative bacteria, while the main pathogenic bacteria in double-J stent were enterococcus faecalis (27.53%) of Gram positive bacteria. The resistance rate of Gram positive bacteria in double-J stent to vancomycin, ciprofloxacin, meropenem and piperacillin/tazobactam was significantly higher than that in urine (P<0.05). The resistance rate of Gram negative bacteria in double-J stent to imipenem, cefepime, piperacillin/tazobactam, meropenem and cefoperazone/sulbactam was significantly higher than that in urine (P<0.05).

Conclusion

Double-J stent associated urinary tract infection is more common in women than in men. Escherichia coli and Enterococcus faecalis are the main pathogens, and the pathogens show strong drug resistance.

Antibiotic delivery from bone-targeted mesoporous silica nanoparticles for the treatment of osteomyelitis caused by methicillin-resistant Staphylococcus aureus

Osteomyelitis is a hard-to-treat infection of the bone and bone marrow that is mainly caused by Staphylococcus aureus, with an increasing incidence of methicillin-resistant S. aureus (MRSA). Owing to the aggressiveness of these bacteria in colonizing and destroying the bone, systemic antibiotic treatments fail to eradicate the infection. Instead, it normally entails surgery to remove the dead or infected bone. In this work, we report bone-targeted mesoporous silica nanoparticles for the treatment of osteomyelitis. The nanoparticles have been engineered with a functional gelatine/colistin coating able to hamper premature release from the mesopores while effectively disaggregating the bacterial biofilm. Because antibiotic resistance is a global emergency, we have designed two sets of identical nanoparticles, carrying each of them a clinically relevant antibiotic, that have demonstrated to have synergistic effect. The bone-targeted nanoparticles have been thoroughly evaluated in vitro and in vivo, obtaining a notable reduction of the amount of bacteria in the bone in just 24 h after only one dose, and paving the way for localized, nanoparticle-mediated treatment of MRSA-caused osteomyelitis. STATEMENT OF SIGNIFICANCE: In this work, we propose the use of bone-targeted mesoporous silica nanoparticles to address S. aureus-caused osteomyelitis that render synergistic therapeutic effect via multidrug delivery. Because the bacterial biofilm is responsible for an aggressive surgical approach and prolonged antibiotic treatment, the nanoparticles have been functionalized with a functional coating able to both disaggregate the biofilm, hamper premature antibiotic release and protect the intact bone. These engineered nanoparticles are able to effectively target bone tissue both in vitro and in vivo, showing high biocompatibility and elevated antibacterial effect.

Arabic gum plus colistin coated moxifloxacin-loaded nanoparticles for the treatment of bone infection caused by Escherichia coli

Osteomyelitis is an inflammatory process of bone and bone marrow that may even lead to patient death. Even though this disease is mainly caused by Gram-positive organisms, the proportion of bone infections caused by Gram-negative bacteria, such as Escherichia coli, has significantly increased in recent years. In this work, mesoporous silica nanoparticles have been employed as platform to engineer a nanomedicine able to eradicate E. coli- related bone infections. For that purpose, the nanoparticles have been loaded with moxifloxacin and further functionalized with Arabic gum and colistin (AG+CO-coated MX-loaded MSNs). The nanosystem demonstrated high affinity toward E. coli biofilm matrix, thanks to AG coating, and marked antibacterial effect because of the bactericidal effect of moxifloxacin and the disaggregating effect of colistin. AG+CO-coated MX-loaded MSNs were able to eradicate the infection developed on a trabecular bone in vitro and showed pronounced antibacterial efficacy in vivo against an osteomyelitis provoked by E. coli. Furthermore, AG+CO-coated MX-loaded MSNs were shown to be essentially non-cytotoxic with only slight effect on cell proliferation and mild hepatotoxicity, which might be attributed to the nature of both antibiotics. In view of these results, these nanoparticles may be considered as a promising treatment for bone infections caused by enterobacteria, such as E. coli, and introduce a general strategy against bone infections based on the implementation of antibiotics with different but complementary activity into a single nanocarrier. STATEMENT OF SIGNIFICANCE: In this work, we propose a methodology to address E.coli bone infections by using moxifloxacin-loaded mesoporous silica nanoparticles coated with Arabic gum containing colistin (AG+CO-coated MX-loaded MSNs). The in vitro evaluation of this nanosystem demonstrated high affinity toward E. coli biofilm matrix thanks to the Arabic gum coating, a disaggregating and antibacterial effect of colistin, and a remarkable antibiofilm action because of the bactericidal ability of moxifloxacin and colistin. This anti-E. coli capacity of AG+CO-coated MX-loaded MSNs was brought out in an in vivo rabbit model of osteomyelitis where the nanosystem was able to eradicate more than 90% of the bacterial load within the infected bone.

Effects of Tigecycline Combined with Azithromycin Against Biofilms of Multidrug-Resistant Stenotrophomonas maltophilia Isolates from a Patient in China

Purpose

Our aim was to investigate in vitro biofilm formation by S. maltophilia and the effects of antibacterial agents used to prevent biofilm formation.

Methods

Two trimethoprim/sulfamethoxazole-resistant S. maltophilia strains were isolated from the pleural effusion of a patient with cancer. The minimum inhibitory concentrations (MICs) of amikacin, azithromycin, cefoperazone/sulbactam, and tigecycline were determined. The checkerboard method was used to determine the fractional inhibitory concentration indices (FICIs). A crystal violet biofilm assay and confocal laser scanning microscopy (CLSM) were used to observe biofilm formation. In vitro effects of azithromycin combined with tigecycline on biofilms of S. maltophilia strains were tested.

Results

The two S. maltophilia isolates were confirmed to produce strong biofilms. Crystal violet biofilm assay and CLSM analysis of S. maltophilia biofilm were in the initial adhesive stage after 2 h incubation. Biofilm was in the exponential phase of growth at 12 h and reached maximal growth at 36–48 h. Compared with tigecycline or azithromycin alone, the combination of tigecycline and azithromycin increased the inhibiting effect S. maltophilia biofilm biomass after incubation for 12 h. Compared with the control group, in almost all strains treated with tigecycline and azithromycin, the biofilm was significantly suppressed significance (P<0.001). We found that 2x MIC azithromycin combined with 1x MIC tigecycline had the best inhibiting effect against the biofilm, the biofilm inhibition rates of three strains were all over 60%, the biofilm thickness was inhibited from 36.00 ± 4.00 μm to 8.00 μm, from 40.00 μm to 6.67± 2.31 μm, and from 32.00 μm to 13.33 ± 2.31 μm in SMA1, SMA2 and ATCC17666, respectively.

Conclusion

Azithromycin combined with tigecycline inhibited biofilm formation by S. maltophilia. Our study provides an experimental basis for a possible optimal treatment strategy for S. maltophilia biofilm-related infections.

Biofilm Formation and Antibiotic Resistance Phenotype of Helicobacter pylori Clinical Isolates

We evaluated biofilm formation of clinical Helicobacter pylori isolates from Indonesia and its relation to antibiotic resistance. We determined the minimum inhibition concentration (MIC) of amoxicillin, clarithromycin, levofloxacin, metronidazole and tetracycline by the Etest to measure the planktonic susceptibility of 101 H. pylori strains. Biofilms were quantified by the crystal violet method. The minimum biofilm eradication concentration (MBEC) was obtained by measuring the survival of bacteria in a biofilm after exposure to antibiotics. The majority of the strains formed a biofilm (93.1% (94/101)), including weak (75.5%) and strong (24.5%) biofilm-formers. Planktonic resistant and sensitive strains produced relatively equal amounts of biofilms. The resistance proportion, shown by the MBEC measurement, was higher in the strong biofilm group for all antibiotics compared to the weak biofilm group, especially for clarithromycin (p = 0.002). Several cases showed sensitivity by the MIC measurement, but resistance according to the MBEC measurements (amoxicillin, 47.6%; tetracycline, 57.1%; clarithromycin, 19.0%; levofloxacin, 38.1%; and metronidazole 38.1%). Thus, biofilm formation may increase the survival of H. pylori and its resistance to antibiotics. Biofilm-related antibiotic resistance should be evaluated with antibiotic susceptibility.

Stenotrophomonas maltophilia biofilm: its role in infectious diseases

Introduction: Infections caused by the opportunistic Stenotrophomonas maltophilia pathogen in immunocompromised patients are complicated to treat due to antibiotic resistance and the ability of the bacteria to produce biofilm.Areas covered: A MEDLINE/PubMed search was performed of available literature to describe the role of biofilm produced by S. maltophilia in the diseases it causes, including biofilm-influencing factors, the biofilm forming process and composition. The antimicrobial resistance due to S. maltophilia biofilm production and current antibiofilm strategies is also included.Expert opinion: Through the production of biofilm, S. maltophilia strains can easily adhere to the surfaces in hospital settings and aid in its transmission. The biofilm can also cause antibiotic tolerance rendering some of the therapeutic options ineffective, causing setbacks in the selection of an appropriate treatment. Conventional susceptibility tests do not yet offer therapeutic guidelines to treat biofilm-associated infections. Current S. maltophilia biofilm control strategies include natural and synthetic compounds, chelating agents, and commonly prescribed antibiotics. As biofilm age and matrix composition affect the level of antibiotic tolerance, their characterization should be included in biofilm susceptibility testing, in addition to molecular and proteomic analyzes. As for now, several commonly recommended antibiotics can be used to treat biofilm-related S. maltophilia infections.

Influence of biofilms on morbidity associated with short-term indwelling ureteral stents: a prospective observational study

PURPOSE

To evaluate the influence of biofilms on morbidity associated with short-term ureteral stenting using contemporary methods of biofilm examination and validated assessment of symptoms.

METHODS

Patients undergoing temporary ureteral stenting for secondary ureterorenoscopy due to urinary calculi were prospectively included. The German Ureteral Stent Symptoms Questionnaire (USSQ) was used to assess stent-associated morbidity. Biofilms were removed from stents using 'pinhole extraction', a novel, validated, abrasion-based technique. Extracted biofilms were analyzed for total mass, bacterial load and mineral components. Correlation between total biofilm mass and USSQ total score was the primary outcome variable analyzed using Spearman correlation. Secondary outcomes included correlations between various biofilm characteristics and symptoms.

RESULTS

94 patients were included in the analysis. Extracted biofilm mass had a median of 37.0 mg (0-310.2 mg) per stent. No correlation between total biofilm mass and USSQ total score was found (Spearman r = 0.012; p = 0.911). Correlations between biofilm characteristics and morbidity were generally weak and not significant. Significant correlations could be found between biofilm mass and hematuria (r = 0.280; p = 0.007), and between the number of bacteria (qPCR) and the USSQ subscore for pain (r = 0.243; p = 0.019) and the intake of analgesics (r = 0.259; p = 0.012).

CONCLUSION

Based on elaborated biofilm examination methods and validated self-reported outcome measures, our findings indicate that biofilms might aggravate some lower urinary tract symptoms but are not the main trigger for stent-associated morbidity in short-term ureteral stenting.

Inhibition of Pseudomonas aeruginosa PAO1 adhesion to and invasion of A549 lung epithelial cells by natural extracts

Pseudomonas aeruginosa colonizes the lungs in cystic fibrosis (CF) and mechanically ventilated patients by binding to the cellular receptors on the surface of the lung epithelium. Studies have shown that blocking this interaction could be achieved with sub-minimum inhibitory concentrations of antibiotics such as ciprofloxacin. The development of bacterial resistance is a probable drawback of such an intervention. The use of natural extracts to interfere with bacterial adhesion and invasion has recently gained substantial attention and is hypothesized to inhibit bacterial binding and consequently prevent or reduce pathogenicity. This study used an A549 lung epithelial cell infection model, and the results revealed that a combination of aqueous cranberry extract with ciprofloxacin could completely prevent the adhesion and invasion of P. aeruginosa PAO1 compared to the untreated control. All of the natural extracts (cranberry, dextran, and soybean extracts) and ciprofloxacin showed a significant reduction (P<0.0001) in P. aeruginosa PAO1 adhesion to and invasion of lung epithelial cells relative to the control. The cranberry, dextran, and soybean extracts could substantially increase the anti-adhesion and anti-invasion effects of ciprofloxacin to the averages of 100% (P<0.0001), 80% (P<0.0001), and 60% (P<0.0001), respectively. Those extracts might result in a lower rate of the development of bacterial resistance; they are relatively safe and inexpensive agents, and utilizing such extracts, alone or in combination with ciprofloxacin, as potential anti-adhesion and anti-invasion remedies, could be valuable in preventing or reducing P. aeruginosa lung infections.

Modulation of biofilm of strains isolated from patients with chronic obstructive pulmonary disease by levofloxacin, moxifloxacin, ciprofloxacin, amoxicillin/clavulanic acid and ceftriaxone

The ability of levofloxacin, moxifloxacin, ciprofloxacin, amoxicillin/clavulanic acid and ceftriaxone to interfere on biofilm produced by Pseudomonas aeruginosa, Haemophilus influenzae and Streptococcus pneumoniae isolated from patients with chronic obstructive pulmonary disease was evaluated. The effects of antibiotics were evaluated on formation of biofilm (at 1/2, 1/4 and 1/8 X MIC) and on preformed biofilm (at epithelial lining fluid peak concentrations) by means of a spectrophotometric method. Levofloxacin was the most active compound followed by ciprofloxacin, moxifloxacin and amoxicillin/clavulanic acid and ceftriaxone. Levofloxacin may contribute to clear the reservoir of pathogens involved in chronic obstructive pulmonary disease, thus leading to decreased occurrence of acute exacerbations.