Characterization of carbapenem-resistant but cephalosporin-susceptible Pseudomonas aeruginosa

In this study, mechanisms of carbapenem resistance in carbapenem-resistant but cephalosporin-susceptible (Car-R/Ceph-S) Pseudomonas aeruginosa were investigated. A total of 243 P. aeruginosa isolates were studied. The disk diffusion and agar dilution methods were used for determination of antibiotic susceptibility patterns. AmpC and efflux pump overproductions were detected by phenotypic methods. The presence of carbapenemase-encoding genes was detected by polymerase chain reaction (PCR). The expression of OprD, MexAB-OprM, and MexXY-OprM efflux pumps was assessed by real-time PCR. According to disk diffusion method, altogether 116 P. aeruginosa isolates (47.7%) were carbapenem-resistant and among them, 23 isolates (19.8%) were cephalosporin-susceptible. Carbapenemase producer was not detected. Overexpression of AmpC was detected in one (4.3%) isolate that was ceftazidime-susceptible but cefepime-resistant. Overexpression of MexAB-OprM and MexXY-OprM efflux pumps was detected in 12 (60.9%) and 16 (68.8%) of isolates, respectively. A total of 16 (68.8%) isolates showed decreased expression of OprD. The Car-R/Ceph-S P. aeruginosa did not develop by carbapenemase production. The resistance to carbapenem was mediated in our clinical isolates by decreased expression of OprD and overexpression of MexAB-OprM and MexXY-OprM efflux systems or the combination of these mechanisms

Curcumin Nanocrystals: Production, Physicochemical Assessment, and In Vitro Evaluation of the Antimicrobial Effects against Bacterial Loading of the Implant Fixture

Background: This study aimed to prepare and study physicochemical properties as well as the antibacterial action of curcumin nanocrystals inside the implant fixture against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Enterococcus faecalis (E. faecalis). Methods: Curcumin nanocrystals were prepared via precipitation combined with the spray drying method. The produced curcumin nanocrystals were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Moreover, the in vitro antimicrobial effect of curcumin nanocrystals inside the implant fixture was assessed against E. coli, S. aureus, and E. faecalis. All implant-abutment assemblies were immersed in bacterial suspensions and were incubated at 24, 48, and 72 h. The contents of each implant were cultured to count the colony of bacteria at 37 ◦C for 24 h. Results: The prepared curcumin nanocrystals with a mean particle size of 95 nm and spherical morphology exhibited a removal rate of 99.99% for all bacteria. In addition, the colony-forming unit (CFU) of bacteria in exposure to nanocrystals significantly was reduced (p < 0.010) by increasing the time. Conclusions: Curcumin nanocrystals can be used inside the implant fixture as an antimicrobial agent in order to more stabilization of the implant

Antibacterial and Antibiofilm Activity of Grape Seed Extract Against Carbapenem Resistant and Biofilm Producer Enterobacteriaceae

Background and objectives: Carbapenem-resistant and biofilm producing Enterobacteriaceaeare a major health problem. This study was carried to determine the antibacterial and antibiofilm activity of grape seed extract (GSE) against carbapenem-resistant and biofilm producing Enterobacteriaceae isolates. Methods: Antibiotics susceptibility patterns were detected by the disk diffusion method. carbapenem-resistant Enterobacteriaceae (CRE) isolates were screened by carbapenems disks and imipenem minimum inhibitory concentrations (MIC). The biofilm formation was detected by the microplate method. The carbapenemase genes were detected by PCR. The total polyphenolic content of GSE was determinate by Folin Ciocalteu technique. The antibacterial and antibiofilm effects of GSE were tested by the MIC and biofilm inhibitory concentration (BIC), respectively. Results: In this study, total phenolic content of extracted 1 gram of GSE was equivalent to 700 mg gallic acid. Eighteen non-duplicated CRE isolates were selected. All isolates were fosfomycin susceptible. Variable frequency of resistance to the other tested antibiotics was observed. The blaOXA-48 was the most common carbapenemase type. Among 18 isolates, 13 were biofilm producer while GSE inhibited CRE growth at 1024 µg/mL for 15 isolates and 2048 µg/mL for three isolates. Biofilm production was inhibited by GSE in 2000 µg/mL, 4000 µg/mL and 8000 µg/mL after 72 h incubation. Conclusion: The significant antibacterial and antibiofilm effects of GSE suggested GSE as a promising candidate for treatment of infections caused by these organisms

Importance of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs) in cancer cells

Abstract Background In most regions, cancer ranks the second most frequent cause of death following cardiovascular disorders. Aim In this article, we review the various aspects of glycolysis with a focus on types of MCTs and the importance of lactate in cancer cells. Results and Discussion Metabolic changes are one of the first and most important alterations in cancer cells. Cancer cells use different pathways to survive, energy generation, growth, and proliferation compared to normal cells. The increase in glycolysis, which produces substances such as lactate and pyruvate, has an important role in metastases and invasion of cancer cells. Two important cellular proteins that play a role in the production and transport of lactate include lactate dehydrogenase and monocarboxylate transporters (MCTs). These molecules by their various isoforms and different tissue distribution help to escape the immune system and expansion of cancer cells under different conditions

In vitro synergy of antibiotic combinations against planktonic and biofilm Pseudomonas aeruginosa

Aim: The combination of different antimicrobial agents and subsequent synergetic effects may be beneficial in treatment of infections. The aim of the present study was to determine antibiotic susceptibility patterns of clinical isolates of and the effect of different antibiotic combinations against the multidrug-resistant (MDR), biofilm-producing bacterium . Methods: Thirty-six clinical isolates were evaluated. The disk diffusion method was performed to determine antibiotic susceptibility patterns according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The minimum inhibitory concentration of antimicrobial agents for the test organisms was determined by the broth microdilution method. To determine synergetic effects of the combinations of agents, the checkerboard assay and the fractional inhibitory concentration were used. The biofilm inhibitory concentration was determined to detect any inhibitory effect of antibiotics against the biofilm. Results: High levels of resistance were detected against most antibiotics, except colistin and polymyxin. According to the disk diffusion method, 58.3% of isolates were MDR. A synergetic effect between amikacin/ceftazidime, tobramycin/colistin and ceftazidime/colistin was found in 55.6%, 58.3% and 52.8% of isolates, respectively. A significant synergetic effect against biofilm-producing isolates was observed for the combination of tobramycin (0.5–1 µg/ml) and clarithromycin (256–512 µg/ml).Conclusion: Combinations of antibiotics have a different activity on the biofilm and planktonic forms of . Consequently, separate detection of antibacterial and antibiofilm effects of the antibiotic combinations may be useful in guiding the antibiotic therapy

Antibacterial Effects of Curcumin Nanocrystals against <i>Porphyromonas gingivalis</i> Isolated from Patients with Implant Failure

Background. Despite their benefits, dental implants may sometimes fail for a diversity of causes; the most common reasons of failure are infection and bone loss. Porphyromonas gingivalis (P. gingivalis) bacteria show a major role in peri-implantitis infection and dental implant failure. Methods. In this study, the prevalence of P. gingivalis isolated from the gingival crevicular fluid (GCF) of fifteen Iranian patients with implant failure (more than 1/3 of the implant length), who had average oral and dental hygiene and no antibiotic use for at least one month, was determined. Moreover, the antimicrobial effects of curcumin nanocrystals against isolated P. gingivalis were investigated. The collected samples from patients were transferred to a microbiology laboratory to culture. The presence of P. gingivalis in the culture media was confirmed using a trypsin reagent test. An isolate from a patient with the highest colony count was selected to evaluate the antibacterial effects of curcumin nanoparticles. The inhibition zone diameter, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) were determined. Results. Out of fifteen patients, eight (53.33%) were positive for the presence of P. gingivalis. The results of the microbial tests showed that curcumin nanoparticles had an MIC of 6.25 µg/mL and an MBC of 12.5 µg/mL. Conclusions. The use of curcumin nanoparticles may control the bacterial infection around the implant

The Antimicrobial and Anti-Biofilm Effects of <i>Hypericum perforatum</i> Oil on Common Pathogens of Periodontitis: An In Vitro Study

The antibacterial and anti-biofilm effects of Hypericum perforatum oil against the common pathogens of periodontitis (Escherichia coli, Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, Porphyromonas gingivalis) was investigated. Disk diffusion (DD), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) approaches were applied to test the antimicrobial effects. In order to determine the anti-biofilm effects, the amount of bacterial biofilm formation was assessed using the microtiter plate technique. The anti-biofilm effects were then confirmed by determining the minimum biofilm inhibitor concentration (MBIC). The MIC, MBC, MBIC, and DD values were 64, 256, 512 μg/mL, and 14 mm for Staphylococcus aureus; 128, 256, 512 μg/mL, and 16 mm for Streptococcus mutans; 256, 512, 256 μg/mL, and 20 mm for Escherichia coli; 32, 128, 512 µg/mL, and 16 mm for Enterococcus faecalis; and 64, 128, 256 µg/mL, and 15 mm for Porphyromonas gingivalis, respectively. According to our results, Hypericum perforatum oil has antibacterial and anti-biofilm properties against the common bacteria associated with periodontitis

Biocompatibility, cytotoxicity and antibacterial effects of meropenem-loaded mesoporous silica nanoparticles against carbapenem-resistant Enterobacteriaceae

AbstractBackground The ever-increasing resistance to antimicrobial agents among bacteria associated with nosocomial infections indicate the necessity of new antimicrobial therapy. The nanoparticles are considered as new drug delivery systems to increase the efficiency and decrease the unfavourable effects of the antimicrobial agents.Methods Herein we report the preparation and characterization of mesoporous silica nanoparticles (MSNs) loaded with meropenem against carbapenem-resistant Enterobacteriaceae. The antimicrobial effect of meropenem-loaded MSNs was determined against Enterobacteriaceae using the minimum inhibitory (MIC) method. The biocompatibility of meropenem-loaded MSNs was studied by the impact on the haemolysis and sedimentation rates of human red blood cells (HRBCs). Cytotoxicity of the meropenem-loaded MSNs was studied by the MTT test (hBM-MSC cell viability).Results The meropenem-loaded MSNs have shown antibacterial activity on all isolates at different MIC values lower than MICs of meropenem. Free MSNs did not show any significant antibacterial effect. Meropenem-loaded MSNs have no significant effect on haemolysis and ESR of HRBCs. The viability of hBM-MSC cells treated with serial concentrations of meropenem-loaded MSNs was 92–100%.Conclusion Due to the desirable biocompatibility, low cytotoxicity and the improved antibacterial effect, MSNs can be considered as a promising drug delivery system for meropenem as a potential antimicrobial agent

Molecular Detection and Characterization of the Staphylococcus epidermidis and Staphylococcus haemolyticus Isolated from Hospitalized Patients and Healthcare Workers in Iran

Background. The present study is aimed at surveying the antibiotics resistance profile, biofilm formation ability, staphylococcal cassette chromosome mec (SCCmec) types, and molecular epidemiology of Staphylococcus epidermidis and Staphylococcus haemolyticus isolated from hospitalized patients and healthcare workers in four teaching hospitals in Iran. Methods. In total, 43 Staphylococcus epidermidis and 12 Staphylococcus haemolyticus were isolated from hospitalized patients, and 19 Staphylococcus epidermidis and 7 Staphylococcus haemolyticus isolated from healthcare workers were included in the present study. The antimicrobial resistance profile of isolates was determined using the disk diffusion method. Moreover, the resistance of isolates to methicillin was identified using the cefoxitin disk diffusion test. The microtiter-plate test was used for quantifying biofilm formation. Moreover, the frequency of icaA and icaD genes was determined using PCR assay. The molecular epidemiology of methicillin-resistant isolates was determined using SCCmec typing and pulsed-field gel electrophoresis methods. Results. Among all coagulase-negative staphylococci isolates, the highest resistance rate (81.5%) was seen for cefoxitin and cotrimoxazole. All of the isolates were susceptible to linezolid. Out of the 66 mecA-positive isolates, the most common SCCmec type was the type I (n=23; 34.8%) followed by type IV (n=13; 19.7%). Using pulsed-field gel electrophoresis (PFGE) assay, 27 PFGE types including 14 common types and 13 singletons were obtained among 51 methicillin-resistant S. epidermidis (MRSE) isolates. Moreover, among 12 methicillin-resistant S. haemolyticus (MRSH) isolates, 8 PFGE types were detected, of which 5 PFGE types were singletons. Conclusion. The high rate of resistance to antibiotics as well as the possibility of cross-infection shows the importance of a pattern shift in the management and controlling programs of coagulase-negative staphylococci, especially in healthcare centers. Clinical trial registration. The present study is not a clinical trial study. Thus, a registration number is not required