Detection of multidrug-resistant bacteria in the nasal cavities and evaluation of sinus disorders in patients undergoing Le Fort I osteotomy.

INTRODUCTION: Orthognathic surgery can lead to sinus alterations, including sinusitis, attributed to the exposure of maxillary sinuses during Le Fort I osteotomy. Furthermore, being a hospital-based procedure, there is potential risk of complications arising from bacteria prevalent in such environments. This study evaluated maxillary sinusitis occurrence and the presence of multidrug-resistant bacteria in the nasal cavity before and after orthognathic surgery. METHODS: Ten patients with dentofacial deformities underwent Le Fort I osteotomy. Clinical evaluations using SNOT-22 questionnaire were performed, and nasal cavity samples were collected pre-surgery and 3-6 months post-surgery to quantify total mesophilic bacteria and detect Staphylococcus aureus, Acinetobacter baumannii, and Klebsiella pneumoniae. Cone Beam Computed Tomography (CBCT) was performed pre- and post-operatively, and the results were evaluated using the Lund-Mackay system. This study was registered and approved by the Research Ethics Committee of PUCRS (No. 4.683.066). RESULTS: The evaluation of SNOT-22 revealed that five patients showed an improvement in symptoms, while two remained in the same range of interpretation. One patient developed post-operative maxillary sinusitis, which was not detected at the time of evaluation by SNOT-22 or CBCT. CBCT showed a worsening sinus condition in three patients, two of whom had a significant increase in total bacteria count in their nasal cavities. The Brodsky scale was used to assess hypertrophy in palatine tonsils, where 60% of the subjects had grade 1 tonsils, 20% had grade 2 and 20% had grade 3. None of the patients had grade 4 tonsils, which would indicate more than 75% obstruction. Two patients harboured S. aureus and K. pneumoniae in their nasal cavities. Notably, K. pneumoniae, which was multidrug-resistant, was present in the nasal cavity of patients even before surgery, but this did not result in maxillary sinusitis, likely due to the patients' young and healthy condition. CONCLUSION: There was an improvement in signs and symptoms of maxillary sinusitis and quality of life in most patients after orthognathic surgery. However, some patients may still harbour multidrug-resistant bacteria, even if they are asymptomatic. Therefore, a thorough pre-operative assessment is essential to avoid difficult-to-treat post-operative complications.

Synergistic Antibiofilm Action of Cinnamomum verum and Brazilian Green Propolis Hydroethanolic Extracts against Multidrug-Resistant Strains of Acinetobacter baumannii and Pseudomonas aeruginosa and Their Biocompatibility on Human Keratinocytes.

The accumulated dental biofilm can be a source of oral bacteria that are aspirated into the lower respiratory tract causing ventilator-associated pneumonia in hospitalized patients. The aim of this study was to evaluate the synergistic antibiofilm action of the produced and phytochemically characterized extracts of Cinnamomum verum and Brazilian green propolis (BGP) hydroethanolic extracts against multidrug-resistant clinical strains of Acinetobacter baumannii and Pseudomonas aeruginosa, in addition to their biocompatibility on human keratinocyte cell lines (HaCaT). For this, High-performance liquid chromatography analysis of the plant extracts was performed; then the minimum inhibitory and minimum bactericidal concentrations of the extracts were determined; and antibiofilm activity was evaluated with MTT assay to prevent biofilm formation and to reduce the mature biofilms. The cytotoxicity of the extracts was verified using the MTT colorimetric test, evaluating the cellular enzymatic activity. The data were analyzed with one-way ANOVA and Tukey's tests as well as Kruskal-Wallis and Dunn's tests, considering a significance level of 5%. It was possible to identify the cinnamic aldehyde in C. verum and p-coumaric, caffeic, and caffeoylquinic acids as well as flavonoids such as kaempferol and kaempferide and Artepillin-C in BGP. The combined extracts were effective in preventing biofilm formation and reducing the mature biofilms of A. baumannii and P. aeruginosa. Moreover, both extracts were biocompatible in different concentrations. Therefore, C. verum and BGP hydroethanolic extracts have bactericidal and antibiofilm action against multidrug resistant strains of A. baumannii and P. aeruginosa. In addition, the combined extracts were capable of expressively inhibiting the formation of A. baumannii and P. aeruginosa biofilms (prophylactic effect) acting similarly to 0.12% chlorhexidine gluconate.

Comparison of the antiseptic effectiveness of octenidine dihydrochloride with povidone-iodine for Acinetobacter baumannii contaminated wounds in Wistar rat.

INTRODUCTION: Effective antiseptic use is essential in healthcare settings to prevent the spread of diseases, especially in areas with high patient traffic and exposure to various pathogens. One essential pathogenic germ is Acinetobacter baumannii. Octenidine and povidone-iodine have been demonstrated to be effective against A. baumannii in vitro. This study will compare octenidine dihydrochloride and povidone-iodine as wound-cleansing solutions for wounds contaminated with A. baumannii in vivo. MATERIALS AND METHODS: Twenty-four rats were divided into three groups: normal saline, octenidine dihydrochloride and povidone-iodine. Wounds were made on the rats' backs, and A. baumannii germs were inoculated into the wounds. After 3 hours, the wound was irrigated with wound cleansing solution according to the group for 30 seconds. Each wound was taken swab culture before and after wound irrigation and tissue culture 5 hours after wound irrigation. RESULTS: All specimens showed bacterial colony growth with a median value of 1.22 × 105 CFU before irrigation. Wound irrigation with normal saline did not reduce colony counts, while there was a 3-log reduction to 5-log reduction in the octenidine and povidone-iodine groups. Statistically, there was no significant difference in the mean number of colonies between the octenidine and povidone-iodine groups after irrigation (p = 0.535). However, 3 hours after irrigation, all specimens that experienced 3-log reduction showed regrowth to more than 1 × 105 CFU. In contrast, specimens subjected to 5-log reduction did not exhibit any regrowth. CONCLUSION: The antiseptic effectiveness of octenidine dihydrochloride is equivalent to povidone-iodine in eradicating A. baumannii colonies in wounds in vivo.

Using engineered water nanostructures (EWNS) for wound disinfection: Case study of Acinetobacter baumannii inactivation on skin and the inhibition of biofilm formation.

Engineered water nanostructures (EWNS) were utilized to deliver a cocktail of nature derived antimicrobials, to assess their efficacy as a solution to the problem of wound infections. The wound related microorganism Acinetobacter baumannii was inoculated on stainless steel and porcine skin and treated with EWNS. EWNS were able to reduce A. baumannii on stainless steel by 4.79 logs in 15 min, and 2 logs in 30 min on porcine skin. The EWNS were able to reduce the strength of A. baumannii biofilm on stainless steel by 87.31% as measured with the XTT assay (P < .001) and 86.27% in cellular counts (P < .001), after two EWNS interventions of 30 min each. Total antimicrobial dose delivered to the surface was 1.42 ng. SEM of biofilms after EWNS treatment showed reduced biomass. These results indicate that the EWNS technology has potential for application in field of wound disinfection and healing.

Glycosphingolipids (GSLs) from Sphingomonas paucimobilis Increase the Efficacy of Liposome-Based Nanovaccine against Acinetobacter baumannii-Associated Pneumonia in Immunocompetent and Immunocompromised Mice.

Due to the high propensity of drug resistance in Acinetobacter baumannii, the number of currently available therapeutic drugs has become very limited. Thus, it becomes incredibly important to prepare an effective vaccine formulation capable of eliciting an effective immune response against A. baumannii. In this study, we prepared a liposomal vaccine formulation bearing glycosphingolipids (GSLs) from Sphingomonas paucimobilis and loaded with the whole cell antigen (WCAgs-GSLs-liposomes) of A. baumannii. The immune-stimulating potential and prophylactic efficacy of WCAgs-GSLs-liposomes were compared with those of WCAgs-liposomes (without GSLs) or free WCAgs in both immunocompetent and immunodeficient mice. The efficacy of vaccine formulations was determined by analyzing antibody titer, cytokine levels, and survival studies in the immunized mice. The findings revealed that vaccination with WCAgs-GSLs-liposomes stimulated a greater secretion of antibodies and cytokines, higher lymphocyte proliferation, and increased expression of the co-stimulatory molecules. Anti-sera from WCAgs-GSLs-liposomes-immunized mice remarkably reduced the biofilm formation by A. baumannii. Most importantly, WCAgs-GSLs-liposomes-vaccinated mice demonstrated a higher defiance against the pathogen, as compared to the immunizations with WCAgs-liposomes (without GSLs) or free WCAgs. Immunocompetent mice immunized with WCAgs-GSLs-liposomes showed a 100% survival rate, while those immunized with WCAgs-liposomes exhibited a 60% survival rate. The protective effect of WCAgs-GSLs-liposomes was also found to be higher in immunocompromised mice, as the immunized mice showed a 50% survival rate, which was greater than the 20% survival rate of those immunized with WCAgs-liposomes. The survival data was also supported by the findings of bacterial load and histological analysis that substantiated the greatest prophylactic potential of the WCAgs-GSLs-liposomes. These findings recommend that WCAgs-GSLs-liposomes may be reckoned as a prospective vaccine to protect the persons against A. baumannii infection.

In vitroassessment of green polyhydroxybutyrate/chitosan blend loaded with kaempferol nanocrystals as a potential dressing for infected wounds.

Despite the major medical advancements in recent decades, treating infected wounds successfully remains a challenge. In this research, a functional blend of Polyhydroxybutyrate (PHB) and Chitosan (Cs) was developed for wound infection mitigation with tailored biological and physicochemical properties. Water insoluble kaempferol (KPF) was pre-formulated to water soluble KPF nanocrystals (KPF-NCs) with fine particle size of 145 ± 11 nm, and high colloidal stability (-31 ± 0.4 mV) to improve its drug transdermal delivery. PHB-Cs-KPF-NCs (1:2 ratio) film owned the best physical properties in terms of high breathability, thermal stability and mechanical strength (33 ± 1 MPa). Besides, XRD and FTIR findings indicated the interaction between Cs, PHB and KPF, reducing the film crystallinity. The scanning electron microscopy of the film displayed a highly interconnected porous morphology. KPF-NCs were integrated in PHB-Cs matrix with a marked encapsulation efficiency of 96.6%. The enhanced drug-loading film showed a sustain release pattern of KPF-NCs over 48 h. Interestingly, the developed blend possessed an impressive blood clotting capacity within 20 min. Furthermore, we presented a new naturally-sourced mixture of Cs+KPF-NCs with powerful antibacterial effects against MDRStaphylococcus aureusandAcentibacter baumanniiat very low concentrations. The membrane evidenced a remarkable antibacterial naturein vitrowith almost 100% cell viability reduction against the study strains after 48 h. By virtue of these advantages, this green blend is highly proposed for optimal wound care.

Investigation into antibacterial and wound healing properties of platelets lysate against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections.

BACKGROUND AND AIM: Treatment of burn wound infections has become a global challenge due to the spread of multidrug-resistant bacteria; therefore, the development of new treatment options for the mentioned infections is essential. Platelets have drawn much attention for this purpose because they are a safe and cost-effective source of different antimicrobial peptides and growth factors. The present study evaluated antibacterial effects and wound healing properties of Platelet-derived Biomaterial (PdB) against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections. METHODS: PdB was prepared through the freezing and thawing process and then, in vitro antibacterial effect was determined by disk diffusion and broth microdilution methods. Afterward, burn wound was inflicted on 56 rats, infected with both bacteria, and topical administration was performed to evaluate antibacterial effects and wound healing properties of PdB. RESULTS: In vitro results showed that PdB inhibited the growth of A. baumannii in the highest dose (0.5), while we did not detect any inhibitory effects against K. pneumoniae. By contrast, PdB significantly inhibited the growth of bacteria in treated animal wounds compared to the control groups (P value < 0.05). Macroscopic assessments pointed to the significant enhancement of wound closure in the treated animals. In addition, histopathological examination demonstrated that treatment of rats with PdB led to a considerable increase in re-epithelialization and attenuated the formation of granulation tissue (P value < 0.05). CONCLUSION: The use of topical PdB is an attractive strategy for treating A. baumannii and K. pneumoniae burn wound infections because it inhibits bacterial growth and promotes wound healing properties.

Adherence ability and serum resistance of different hospital clusters of Acinetobacter baumannii.

The role of mechanical ventilation and catheters in favouring Acinetobacter baumannii infections needs to be better understood. This study evaluated the adherence of 19 isolates of different hospital clusters of A. baumannii to abiotic surfaces and epithelial cells (HEp-2). Of the hydrophobic isolates, 80% adhered to polystyrene, indicating a close relationship between hydrophobicity and adherence. All isolates adhered to epithelial cells to different degrees, and 73·7% showed an aggregated pattern. Analysis of the serum resistance of catheter-tip isolates showed that all were resistant. These worrisome results showed that the high capacity of A. baumannii to adhere to surfaces and survive in human serum could hinder treatment and control of this pathogen.

Evaluation of Syzygium aromaticum aqueous extract as an eco-friendly inhibitor for microbiologically influenced corrosion of carbon steel in oil reservoir environment.

In the present investigation, biocorrosion inhibition efficiency of Syzygium aromaticum (clove) aqueous extract on carbon steel in presence of four corrosion causing bacterial strains (Bacillus subtilis, Streptomyces parvus, Pseudomonas stutzeri, and Acinetobacter baumannii) was explored. Weight loss, potentiodynamic polarization, and AC impedance studies were carried out with and without bacterial strains and clove extract. The results obtained from weight loss and AC impedance studies indicate that these corrosion causing bacterial strains accelerated the biocorrosion reaction and biofilm playing a key role in this process. However, the addition of clove extract into the corrosive medium decreased the corrosion current and increased the solution and charge transfer resistance. The significant inhibition efficiency of about 87% was archived in the mixed consortia system with clove extract. The bioactive compounds were playing an important role in the antibacterial activity of the clove extract. It was revealed that clove extract has both biocidal and corrosion inhibition properties.

Peptide/ß-Peptoid Hybrids with Ultrashort PEG-Like Moieties: Effects on Hydrophobicity, Antibacterial Activity and Hemolytic Properties.

PEGylation of antimicrobial peptides as a shielding tool that increases stability toward proteolytic degradation typically leads to concomitant loss of activity, whereas incorporation of ultrashort PEG-like amino acids (sPEGs) remains essentially unexplored. Here, modification of a peptide/ß-peptoid hybrid with sPEGs was examined with respect to influence on hydrophobicity, antibacterial activity and effect on viability of mammalian cells for a set of 18 oligomers. Intriguingly, the degree of sPEG modification did not significantly affect hydrophobicity as measured by retention in reverse-phase HPLC. Antibacterial activity against both wild-type and drug-resistant strains of Escherichia coli and Acinetobacter baumannii (both Gram-negative pathogens) was retained or slightly improved (MICs in the range 2-16 µg/mL equal to 0.7-5.2 µM). All compounds in the series exhibited less than 10% hemolysis at 400 µg/mL. While the number of sPEG moieties appeared not to be clearly correlated with hemolytic activity, a trend toward slightly increased hemolytic activity was observed for analogues displaying the longest sPEGs. In contrast, within a subseries the viability of HepG2 liver cells was least affected by analogues displaying the longer sPEGs (with IC50 values of ~1280 µg/mL) as compared to most other analogues and the parent peptidomimetic (IC50 values in the range 330-800 µg/mL).

cAST: Capillary-Based Platform for Real-Time Phenotypic Antimicrobial Susceptibility Testing.

Antimicrobial resistance is recognized as one of the greatest emerging threats to public health. Antimicrobial resistant (AMR) microorganisms affect nearly 2 million people a year in the United States alone and place an estimated $20 billion burden on the healthcare system. The rise of AMR microorganisms can be attributed to a combination of overprescription of antimicrobials and a lack of accessible diagnostic methods. Delayed diagnosis is one of the primary reasons for empiric therapy, and diagnostic methods that enable rapid and accurate results are highly desirable to facilitate evidence-based treatment. This is particularly true for clinical situations at the point-of-care where access to state-of-the-art diagnostic equipment is scarce. Here, we present a capillary-based antimicrobial susceptibility testing platform (cAST), a unique approach that offers accelerated assessment of antimicrobial susceptibility in a low-cost and simple testing format. cAST delivers an expedited time-to-readout by means of optical assessment of bacteria incubated in a small capillary form factor along with a resazurin dye. cAST was designed using a combination of off-the-shelf and custom 3D-printed parts, making it extremely suitable for use in resource-limited settings. We demonstrate that growth of bacteria in cAST is approximately 25% faster than in a conventional microplate, further validate the diagnostic performance with clinical isolates, and show that cAST can deliver accurate antimicrobial susceptibility test results within 4-8 h.

A multimodel regime for evaluating effectiveness of antimicrobial wound care products in microbial biofilms.

Microbial biofilms have become increasingly recognized as a cause of wound chronicity. There are several topical antimicrobial wound care products available for use; however, their effectiveness has routinely been demonstrated with planktonic microorganisms. There is no target reference value for antimicrobial effectiveness of wound care products in biofilm models. In addition, data on antimicrobial activity of products in biofilm models are scattered across many test methods in a variety of studies. The aim of this work is to directly compare commercial products containing the commonly used topical antimicrobial agents iodine, silver, polyhexamethylene biguanide, octenidine, hypochlorous acid, benzalkonium chloride, and a surfactant-based topical containing poloxamer 188. Five different in vitro biofilm models of varied complexity were used, incorporating several bacterial pathogens such as Staphylococcus, Enterococcus, Streptococcus, Pseudomonas, Acinetobacter, Klebsiella, and Enterobacter. The fungal pathogens Candida albicans and Candida auris were also evaluated. A multispecies bacterial biofilm model was also used to evaluate the products. Additionally, C. albicans was used in combination with S. aureus and P. aeruginosa in a multikingdom version of the polymicrobial biofilm model. Statistically significant differences in antimicrobial performance were observed between treatments in each model and changing microbial growth conditions or combinations of organisms resulted in significant performance differences for some treatments. The iodine and benzalkonium chloride-containing products were overall the most effective in vitro and were then selected for in vivo evaluation in an infected immunocompromised murine model. Unexpectedly, the iodine product was statistically (P > .05) no different than the untreated control, while the benzalkonium chloride containing product significantly (P < .05) reduced the biofilm compared to untreated control. This body of work demonstrates the importance of not only evaluating antimicrobial wound care products in biofilm models but also the importance of using several different models to gain a comprehensive understanding of products' effectiveness.

Gallium as an Antibacterial Agent: A DFT/SMD Study of the Ga3+/Fe3+ Competition for Binding Bacterial Siderophores.

The urgency of finding novel antibacterial drugs (not only antibiotics), exhibiting different mechanisms of therapeutic action, is significant and has served as a premise for recognizing bacteria's siderophores as a plausible drug target. Bacteria secrete siderophores in order to sequester iron(III) from the surrounding medium by binding the essential metal with high affinity. Gallium, on the other hand, is an "abiogenic" ion, known for its anticancer, antibacterial, and anti-inflammatory action. The rationale behind its therapeutic effect lies in its close mimicry of the ferric ion. Since both ions share various physicochemical characteristics, it is of particular interest to understand if gallium could compete with the native ferric ion for binding siderophores and to decipher which molecular characteristics favor Ga3+ binding over Fe3+ binding. It is also well-known that some bacteria are susceptible to gallium-based therapy, while others are not. Therefore, many questions arise such as the following: (1) Which main group/groups building the siderophores promote gallium's attack? (2) Does the combination of the building blocks affect the preference toward a metal? (3) Does the environment play a crucial role? (4) Could the pH of the medium influence the balance between the ions? We try to address these questions by evaluating the free energy of the competition between Ga3+ and Fe3+ ions for siderophore ligands of various structures, denticities, and charge states by employing the tools of the computational chemistry at the DFT/SMD level. Our results not only fall in line with recent experimental data but also complement our knowledge about "Trojan horse" gallium-based therapy.

MF59 adjuvant enhances the immunogenicity and protective immunity of the OmpK/Omp22 fusion protein from Acineterbacter baumannii through intratracheal inoculation in mice.

Acinetobacter baumannii (A baumannii) is an emerging nosocomial pathogenic bacterium which leads to hospital infections. The increase in drug-resistant A baumannii strains makes it difficult to control by using common antibiotics. The development of effective vaccines is an alternative means to avoid A baumannii infections. In the present study, Balb/c mice were inoculated intratracheally with 30 µg of OmpK/Omp22 fusion protein alone or OmpK/Omp22 formulated with MF59 adjuvant. After two times of boosting at day 14 and 21, the antigen-specific antibody levels and the protective immunity against A baumannii challenge were evaluated. The results showed that the OmpK/Omp22 formulated with MF59 immunized mice produced much higher level of antigen-specific antibodies compared to mice immunized with OmpK/Omp22 alone (P < 0.01). Mice immunized with 30 µg of OmpK/Omp22 formulated with MF59 also provided more potent protection post-challenge, which showed lower bacterial loads in the blood and lung tissue, lower level of blood inflammatory cytokines and higher survival rate (83.3%) than mice immunized with OmpK/Omp22 alone (P < 0.001). In conclusion, this study demonstrated that OmpK/Omp22 fusion protein adjuvanted with MF59 induced superior immune response and better protection than OmpK/Omp22 alone through intratracheal inoculation in mice.

BODIPY-embedded electrospun materials in antimicrobial photodynamic inactivation.

Drug-resistant pathogens, particularly those that result in hospital acquired infections (HAIs), have emerged as a critical priority for the World Health Organization. To address the need for self-disinfecting materials to counter the threat posed by the transmission of these pathogens from surfaces to new hosts, here we investigated if a cationic BODIPY photosensitizer, embedded via electrospinning into nylon and polyacrylonitrile (PAN) nanofibers, was capable of inactivating both bacteria and viruses via antimicrobial photodynamic inactivation (aPDI). Materials characterization, including fiber morphology and the degree of photosensitizer loading, was assessed by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), and demonstrated that the materials were comprised of nanofibers (125-215 nm avg. diameter) that were thermostable to >300 °C. The antimicrobial potencies of the resultant Nylon-BODIPY(+) and PAN-BODIPY(+) nanofiber materials were evaluated against four strains of bacteria recognized by the World Health Organization as either critical or high priority pathogens: Gram-positive strains methicillin-resistant S. aureus (MRSA; ATCC BAA-44) and vancomycin-resistant E. faecium (VRE; ATCC BAA-2320), and Gram-negative strains multidrug-resistant A. baumannii (MDRAB; ATCC BAA-1605) and NDM-1 positive K. pneumoniae (KP; ATCC BAA-2146). Our results demonstrated the detection limit (99.9999%; 6 log units reduction in CFU mL-1) photodynamic inactivation of three strains upon illumination (30-60 min; 40-65 ± 5 mW cm-2; 400-700 nm): MRSA, VRE, and MDRAB, but only minimal inactivation (47-75%) of KP. Antiviral studies employing PAN-BODIPY(+) against vesicular stomatitis virus (VSV), a model enveloped virus, revealed complete inactivation. Taken together, the results demonstrate the potential for electrospun BODIPY(+)-embedded nanofiber materials as the basis for pathogen-specific anti-infective materials, even at low photosensitizer loadings.

Effect of oral hygiene programmes on oral opportunistic pathogens during stroke rehabilitation.

OBJECTIVES: This study was to assess the effectiveness of a conventional oral hygiene care programme (COHCP) and an advanced oral hygiene care programme (AOHCP) on prevalence and viable counts of oral opportunistic pathogens among patients undergoing stroke rehabilitation. METHODS: A total of 94 patients were randomized to two groups. Subjects were block randomized to either (a) COHCP: manual toothbrushing with oral hygiene instruction (OHI); or (b) AOHCP: powered toothbrushing, mouthrinsing with chlorhexidine and OHI. Prevalence and viable counts of oral opportunistic pathogens including yeasts, aerobic and facultative anaerobic gram-negative bacilli, Staphylococcus aureus, were assessed at baseline, the end of 3 and 6 months. RESULTS: No significant difference was observed in the prevalence of oral opportunistic pathogens within each group over the clinical trial period. A significant decrease in the viable counts of S. aureus was found over the clinical trial period within AOHCP group (p < 0.05), while the viable counts of yeasts and anaerobic gram-negative bacillus (AGNB) remained stable within each group. Regression analysis failed to detect an association between intervention and the prevalence/viable counts of oral opportunistic pathogens. CONCLUSIONS: Neither oral healthcare programme significantly affects AGNB, yeast or S. aureus over the study period in terms of prevalence and viable counts.

Tuned Amperometric Detection of Reduced ß-Nicotinamide Adenine Dinucleotide by Allosteric Modulation of the Reductase Component of the p-Hydroxyphenylacetate Hydroxylase Immobilized within a Redox Polymer.

We report the fabrication of an amperometric NADH biosensor system that employs an allosterically modulated bacterial reductase in an adapted osmium(III)-complex-modified redox polymer film for analyte quantification. Chains of complexed Os(III) centers along matrix polymer strings make electrical connection between the immobilized redox protein and a graphite electrode disc, transducing enzymatic oxidation of NADH into a biosensor current. Sustainable anodic signaling required (1) a redox polymer with a formal potential that matched the redox switch of the embedded reductase and avoided interfering redox interactions and (2) formation of a cross-linked enzyme/polymer film for stable biocatalyst entrapment. The activity of the chosen reductase is enhanced upon binding of an effector, i.e. p-hydroxy-phenylacetic acid ( p-HPA), allowing the acceleration of the substrate conversion rate on the sensor surface by in situ addition or preincubation with p-HPA. Acceleration of NADH oxidation amplified the response of the biosensor, with a 1.5-fold increase in the sensitivity of analyte detection, compared to operation without the allosteric modulator. Repetitive quantitative testing of solutions of known NADH concentration verified the performance in terms of reliability and analyte recovery. We herewith established the use of allosteric enzyme modulation and redox polymer-based enzyme electrode wiring for substrate biosensing, a concept that may be applicable to other allosteric enzymes.

Preliminary experience with tigecycline treatment for severe infection in children.

Severe infection is a primary cause of mortality in children facing challenges from multidrug-resistant (MDR) pathogens, particularly MDR Acinetobacter baumannii. Tigecycline has an expanded spectrum of antibacterial activity, and some successful instances of its use in children have been reported. We conducted a retrospective chart review of children treated at a tertiary hospital between May 1, 2012 and May 1, 2017 to examine the efficacy and safety of tigecycline in children with severe infection. A total of 110 patients (69 males) were enrolled in this study, including 46 MDR A. baumannii infection patients, encompassing 51 A. baumannii strains. Totally, the median duration of tigecycline therapy was 10 days (range, 2-47 days), with a clinical improvement rate of 47.27% (52/110). In A. baumannii infection group, the clinical improvement rate was 50% (23/46) and the microbiology eradication rate was 50.98% (26/51). No adverse events were reported during therapy; however, in one case, a 9-year-old boy with hematologic disease developed tooth discoloration.Conclusion: Although some patients benefited from tigecycline, the efficacy and safety of tigecycline should not be overvalued. Additional data from randomized controlled trials are required to assess the administration of tigecycline. What is Known: • Severe infection is a primary cause of mortality in pediatric patients and its treatment is facing challenges from an increasing number of multidrug-resistant (MDR) pathogens. • Tigecycline has an expanded spectrum of antibacterial activity. • Several case reports have indicated that tigecycline could be used as a salvage therapy in children when options are limited or non-existent. What is New: • We found that rate of clinical improvement was different in various groups of different infection. The efficacy of tigecycline should not be overvalued. • Six dosage models and different infection types were observed in our series, with different improvement and eradication rate, indicating that more data are required to identify a proper tigecycline dosage.

Kinetic modeling, recovery, and molecular characterization of poly-beta-hydroxybutyrate polymer in Acinetobacter baumannii isolate P39.

To control the poly-ß-hydroxybutyrate (PHB) biopolymer production by Acinetobacter baumannii isolate P39 kinetic modeling of the fermentation process, polymer downstream processing, enzymological analysis, and molecular characterization of PHA synthase, key biosynthetic enzyme, should be addressed. A. baumannii isolate P39 produced 0.15 g/L PHB after 24 h of incubation with a polymer content of 28% per dry weight. Logistic and Leudeking-Piret models were used for describing cell growth and PHB production, respectively. They showed good agreement with the experimental data describing both cell growth and PHB production (average regression coefficient r2:0.999). The growth-associated production of PHB biopolymer as an electron acceptor was confirmed using Leudeking-Piret model and victim substrate experiment. The best method of recovery of PHB biopolymer was chemical digestion using sodium hypochlorite, since it produced the largest amount of polymer and highest molecular weight (16,000 g/mole) in comparison to other recovery methods. DTNB assay showed high activity of PHA synthase enzyme, 600 U activity, and 153.8 U/mg specific activity. Molecular analysis of PHA synthase enzyme confirmed class III identity. Taken together, micelle model was proposed for polyhydroxybutyrate formation in A. baumannii isolate P39.

[Triton X-100 Enhanced the Detection of Hodge Test and Carba NP Test for Carbapenemase-producing Acinetobacter baumannii Complex].

OBJECTIVE: To find out highly effective phenotypic methods to detect carbapenemase-producing Acinetobacter baumannii (A. baumannii complex) so as to support the epidemiological investigation and clinical application. METHODS: We included 113 A. baumannii complex and compared the detection performance of modified Hodge test, Carba NP test, Triton Hodge test, and the simplified Carba NP-direct test with Tritont X-100. RESULTS: We tested 83 carbapenemase-producing A. baumannii complex and 30 non-carbapenemase producers. The sensitivity and specificity of Hodge test were significantly higher than those of Carba NP test (71.1% versus 35.0%, 100% versus 86.7%, P<0.05, respectively). The sensitivity of Triton Hodge test and Carba NP-direct test was respectively significantly higher than Hodge test and Carba NP test (98.8% versus 71.1%, 85.5% versus 35.0%, P<0.001, respectively ). However, the specificities were comparable (P>0.05). The positive additive effects of the two methods with Triton X-100 were more obvious than those of the methods without Triton X-100 (P<0.001). CONCLUSION: Triton X-100 could increase the sensitivity and positive additive effect on phenotypic detection of A. baumannii complex. Triton Hodge test and Carba NP-direct test were more applicable for clinical routine procedure.